Merge branch 'sd/branch-copy'
authorJunio C Hamano <gitster@pobox.com>
Tue, 3 Oct 2017 06:42:48 +0000 (15:42 +0900)
committerJunio C Hamano <gitster@pobox.com>
Tue, 3 Oct 2017 06:42:48 +0000 (15:42 +0900)
"git branch" learned "-c/-C" to create a new branch by copying an
existing one.

* sd/branch-copy:
branch: fix "copy" to never touch HEAD
branch: add a --copy (-c) option to go with --move (-m)
branch: add test for -m renaming multiple config sections
config: create a function to format section headers

1  2 
Documentation/git-branch.txt
builtin/branch.c
config.c
config.h
refs.c
refs.h
refs/files-backend.c
refs/packed-backend.c
refs/refs-internal.h
t/t3200-branch.sh
index 58f1e5c9c74e187449d6721b4d4322e9cb4733eb,94fd89ddc5ab9373676a46a74ed22662794b2394..fe029ac6fc1a2280893c8ad7c36582c3f891a79e
@@@ -18,6 -18,7 +18,7 @@@ SYNOPSI
  'git branch' (--set-upstream-to=<upstream> | -u <upstream>) [<branchname>]
  'git branch' --unset-upstream [<branchname>]
  'git branch' (-m | -M) [<oldbranch>] <newbranch>
+ 'git branch' (-c | -C) [<oldbranch>] <newbranch>
  'git branch' (-d | -D) [-r] <branchname>...
  'git branch' --edit-description [<branchname>]
  
@@@ -64,6 -65,10 +65,10 @@@ If <oldbranch> had a corresponding refl
  renaming. If <newbranch> exists, -M must be used to force the rename
  to happen.
  
+ The `-c` and `-C` options have the exact same semantics as `-m` and
+ `-M`, except instead of the branch being renamed it along with its
+ config and reflog will be copied to a new name.
  With a `-d` or `-D` option, `<branchname>` will be deleted.  You may
  specify more than one branch for deletion.  If the branch currently
  has a reflog then the reflog will also be deleted.
@@@ -92,10 -97,10 +97,10 @@@ OPTION
        all changes made to the branch ref, enabling use of date
        based sha1 expressions such as "<branchname>@\{yesterday}".
        Note that in non-bare repositories, reflogs are usually
 -      enabled by default by the `core.logallrefupdates` config option.
 +      enabled by default by the `core.logAllRefUpdates` config option.
        The negated form `--no-create-reflog` only overrides an earlier
        `--create-reflog`, but currently does not negate the setting of
 -      `core.logallrefupdates`.
 +      `core.logAllRefUpdates`.
  
  -f::
  --force::
        In combination with `-d` (or `--delete`), allow deleting the
        branch irrespective of its merged status. In combination with
        `-m` (or `--move`), allow renaming the branch even if the new
-       branch name already exists.
+       branch name already exists, the same applies for `-c` (or `--copy`).
  
  -m::
  --move::
  -M::
        Shortcut for `--move --force`.
  
+ -c::
+ --copy::
+       Copy a branch and the corresponding reflog.
+ -C::
+       Shortcut for `--copy --force`.
  --color[=<when>]::
        Color branches to highlight current, local, and
        remote-tracking branches.
@@@ -195,8 -207,10 +207,8 @@@ start-point is either a local or remote
        branch.autoSetupMerge configuration variable is true.
  
  --set-upstream::
 -      If specified branch does not exist yet or if `--force` has been
 -      given, acts exactly like `--track`. Otherwise sets up configuration
 -      like `--track` would when creating the branch, except that where
 -      branch points to is not changed.
 +      As this option had confusing syntax, it is no longer supported.
 +      Please use `--track` or `--set-upstream-to` instead.
  
  -u <upstream>::
  --set-upstream-to=<upstream>::
        Only list branches of the given object.
  
  --format <format>::
 -      A string that interpolates `%(fieldname)` from the object
 -      pointed at by a ref being shown.  The format is the same as
 +      A string that interpolates `%(fieldname)` from a branch ref being shown
 +      and the object it points at.  The format is the same as
        that of linkgit:git-for-each-ref[1].
  
  Examples
diff --combined builtin/branch.c
index 355f9ef5da164d4d3e88872984fced9e9a744a84,e2e3692838e305b7ab8e569fecf6ae8b3a73e6ac..b998e16d0c24b300ce1469749e290c7879af14a7
@@@ -6,7 -6,6 +6,7 @@@
   */
  
  #include "cache.h"
 +#include "config.h"
  #include "color.h"
  #include "refs.h"
  #include "commit.h"
@@@ -28,6 -27,7 +28,7 @@@ static const char * const builtin_branc
        N_("git branch [<options>] [-l] [-f] <branch-name> [<start-point>]"),
        N_("git branch [<options>] [-r] (-d | -D) <branch-name>..."),
        N_("git branch [<options>] (-m | -M) [<old-branch>] <new-branch>"),
+       N_("git branch [<options>] (-c | -C) [<old-branch>] <new-branch>"),
        N_("git branch [<options>] [-r | -a] [--points-at]"),
        N_("git branch [<options>] [-r | -a] [--format]"),
        NULL
@@@ -92,7 -92,7 +93,7 @@@ static int git_branch_config(const cha
                        return config_error_nonbool(var);
                return color_parse(value, branch_colors[slot]);
        }
 -      return git_color_default_config(var, value, cb);
 +      return git_default_config(var, value, cb);
  }
  
  static const char *branch_get_color(enum color_branch ix)
@@@ -335,11 -335,8 +336,11 @@@ static char *build_format(struct ref_fi
        struct strbuf local = STRBUF_INIT;
        struct strbuf remote = STRBUF_INIT;
  
 -      strbuf_addf(&fmt, "%%(if)%%(HEAD)%%(then)* %s%%(else)  %%(end)",
 -                  branch_get_color(BRANCH_COLOR_CURRENT));
 +      strbuf_addf(&local, "%%(if)%%(HEAD)%%(then)* %s%%(else)  %s%%(end)",
 +                  branch_get_color(BRANCH_COLOR_CURRENT),
 +                  branch_get_color(BRANCH_COLOR_LOCAL));
 +      strbuf_addf(&remote, "  %s",
 +                  branch_get_color(BRANCH_COLOR_REMOTE));
  
        if (filter->verbose) {
                struct strbuf obname = STRBUF_INIT;
                else
                        strbuf_addf(&local, "%%(if)%%(upstream:track)%%(then)%%(upstream:track) %%(end)%%(contents:subject)");
  
 -              strbuf_addf(&remote, "%s%%(align:%d,left)%s%%(refname:lstrip=2)%%(end)%s"
 +              strbuf_addf(&remote, "%%(align:%d,left)%s%%(refname:lstrip=2)%%(end)%s"
                            "%%(if)%%(symref)%%(then) -> %%(symref:short)"
                            "%%(else) %s %%(contents:subject)%%(end)",
 -                          branch_get_color(BRANCH_COLOR_REMOTE), maxwidth, quote_literal_for_format(remote_prefix),
 +                          maxwidth, quote_literal_for_format(remote_prefix),
                            branch_get_color(BRANCH_COLOR_RESET), obname.buf);
                strbuf_release(&obname);
        } else {
                strbuf_addf(&local, "%%(refname:lstrip=2)%s%%(if)%%(symref)%%(then) -> %%(symref:short)%%(end)",
                            branch_get_color(BRANCH_COLOR_RESET));
 -              strbuf_addf(&remote, "%s%s%%(refname:lstrip=2)%s%%(if)%%(symref)%%(then) -> %%(symref:short)%%(end)",
 -                          branch_get_color(BRANCH_COLOR_REMOTE), quote_literal_for_format(remote_prefix),
 +              strbuf_addf(&remote, "%s%%(refname:lstrip=2)%s%%(if)%%(symref)%%(then) -> %%(symref:short)%%(end)",
 +                          quote_literal_for_format(remote_prefix),
                            branch_get_color(BRANCH_COLOR_RESET));
        }
  
        return strbuf_detach(&fmt, NULL);
  }
  
 -static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sorting, const char *format)
 +static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sorting, struct ref_format *format)
  {
        int i;
        struct ref_array array;
        if (filter->verbose)
                maxwidth = calc_maxwidth(&array, strlen(remote_prefix));
  
 -      if (!format)
 -              format = to_free = build_format(filter, maxwidth, remote_prefix);
 -      verify_ref_format(format);
 +      if (!format->format)
 +              format->format = to_free = build_format(filter, maxwidth, remote_prefix);
 +      format->use_color = branch_use_color;
 +
 +      if (verify_ref_format(format))
 +              die(_("unable to parse format string"));
  
        ref_array_sort(sorting, &array);
  
        for (i = 0; i < array.nr; i++) {
 -              format_ref_array_item(array.items[i], format, 0, &out);
 +              format_ref_array_item(array.items[i], format, &out);
                if (column_active(colopts)) {
                        assert(!filter->verbose && "--column and --verbose are incompatible");
                         /* format to a string_list to let print_columns() do its job */
@@@ -456,15 -450,19 +457,19 @@@ static void reject_rebase_or_bisect_bra
        free_worktrees(worktrees);
  }
  
- static void rename_branch(const char *oldname, const char *newname, int force)
+ static void copy_or_rename_branch(const char *oldname, const char *newname, int copy, int force)
  {
        struct strbuf oldref = STRBUF_INIT, newref = STRBUF_INIT, logmsg = STRBUF_INIT;
        struct strbuf oldsection = STRBUF_INIT, newsection = STRBUF_INIT;
        int recovery = 0;
        int clobber_head_ok;
  
-       if (!oldname)
-               die(_("cannot rename the current branch while not on any."));
+       if (!oldname) {
+               if (copy)
+                       die(_("cannot copy the current branch while not on any."));
+               else
+                       die(_("cannot rename the current branch while not on any."));
+       }
  
        if (strbuf_check_branch_ref(&oldref, oldname)) {
                /*
  
        reject_rebase_or_bisect_branch(oldref.buf);
  
-       strbuf_addf(&logmsg, "Branch: renamed %s to %s",
-                oldref.buf, newref.buf);
+       if (copy)
+               strbuf_addf(&logmsg, "Branch: copied %s to %s",
+                           oldref.buf, newref.buf);
+       else
+               strbuf_addf(&logmsg, "Branch: renamed %s to %s",
+                           oldref.buf, newref.buf);
  
-       if (rename_ref(oldref.buf, newref.buf, logmsg.buf))
+       if (!copy && rename_ref(oldref.buf, newref.buf, logmsg.buf))
                die(_("Branch rename failed"));
+       if (copy && copy_existing_ref(oldref.buf, newref.buf, logmsg.buf))
+               die(_("Branch copy failed"));
  
-       if (recovery)
-               warning(_("Renamed a misnamed branch '%s' away"), oldref.buf + 11);
+       if (recovery) {
+               if (copy)
+                       warning(_("Copied a misnamed branch '%s' away"),
+                               oldref.buf + 11);
+               else
+                       warning(_("Renamed a misnamed branch '%s' away"),
+                               oldref.buf + 11);
+       }
  
-       if (replace_each_worktree_head_symref(oldref.buf, newref.buf, logmsg.buf))
+       if (!copy &&
+           replace_each_worktree_head_symref(oldref.buf, newref.buf, logmsg.buf))
                die(_("Branch renamed to %s, but HEAD is not updated!"), newname);
  
        strbuf_release(&logmsg);
        strbuf_release(&oldref);
        strbuf_addf(&newsection, "branch.%s", newref.buf + 11);
        strbuf_release(&newref);
-       if (git_config_rename_section(oldsection.buf, newsection.buf) < 0)
+       if (!copy && git_config_rename_section(oldsection.buf, newsection.buf) < 0)
                die(_("Branch is renamed, but update of config-file failed"));
+       if (copy && strcmp(oldname, newname) && git_config_copy_section(oldsection.buf, newsection.buf) < 0)
+               die(_("Branch is copied, but update of config-file failed"));
        strbuf_release(&oldsection);
        strbuf_release(&newsection);
  }
@@@ -544,7 -557,7 +564,7 @@@ static int edit_branch_description(cons
  
  int cmd_branch(int argc, const char **argv, const char *prefix)
  {
-       int delete = 0, rename = 0, force = 0, list = 0;
+       int delete = 0, rename = 0, copy = 0, force = 0, list = 0;
        int reflog = 0, edit_description = 0;
        int quiet = 0, unset_upstream = 0;
        const char *new_upstream = NULL;
        struct ref_filter filter;
        int icase = 0;
        static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
 -      const char *format = NULL;
 +      struct ref_format format = REF_FORMAT_INIT;
  
        struct option options[] = {
                OPT_GROUP(N_("Generic options")),
                OPT__QUIET(&quiet, N_("suppress informational messages")),
                OPT_SET_INT('t', "track",  &track, N_("set up tracking mode (see git-pull(1))"),
                        BRANCH_TRACK_EXPLICIT),
 -              OPT_SET_INT( 0, "set-upstream",  &track, N_("change upstream info"),
 -                      BRANCH_TRACK_OVERRIDE),
 +              { OPTION_SET_INT, 0, "set-upstream", &track, NULL, N_("do not use"),
 +                      PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, BRANCH_TRACK_OVERRIDE },
                OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),
                OPT_BOOL(0, "unset-upstream", &unset_upstream, N_("Unset the upstream info")),
                OPT__COLOR(&branch_use_color, N_("use colored output")),
                OPT_BIT('D', NULL, &delete, N_("delete branch (even if not merged)"), 2),
                OPT_BIT('m', "move", &rename, N_("move/rename a branch and its reflog"), 1),
                OPT_BIT('M', NULL, &rename, N_("move/rename a branch, even if target exists"), 2),
+               OPT_BIT('c', "copy", &copy, N_("copy a branch and its reflog"), 1),
+               OPT_BIT('C', NULL, &copy, N_("copy a branch, even if target exists"), 2),
                OPT_BOOL(0, "list", &list, N_("list branch names")),
                OPT_BOOL('l', "create-reflog", &reflog, N_("create the branch's reflog")),
                OPT_BOOL(0, "edit-description", &edit_description,
                        N_("print only branches of the object"), 0, parse_opt_object_name
                },
                OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
 -              OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
 +              OPT_STRING(  0 , "format", &format.format, N_("format"), N_("format to use for the output")),
                OPT_END(),
        };
  
        argc = parse_options(argc, argv, prefix, options, builtin_branch_usage,
                             0);
  
-       if (!delete && !rename && !edit_description && !new_upstream && !unset_upstream && argc == 0)
+       if (!delete && !rename && !copy && !edit_description && !new_upstream && !unset_upstream && argc == 0)
                list = 1;
  
        if (filter.with_commit || filter.merge != REF_FILTER_MERGED_NONE || filter.points_at.nr ||
            filter.no_commit)
                list = 1;
  
-       if (!!delete + !!rename + !!new_upstream +
+       if (!!delete + !!rename + !!copy + !!new_upstream +
            list + unset_upstream > 1)
                usage_with_options(builtin_branch_usage, options);
  
        if (force) {
                delete *= 2;
                rename *= 2;
+               copy *= 2;
        }
  
        if (delete) {
                if (!sorting)
                        sorting = ref_default_sorting();
                sorting->ignore_case = icase;
 -              print_ref_list(&filter, sorting, format);
 +              print_ref_list(&filter, sorting, &format);
                print_columns(&output, colopts, NULL);
                string_list_clear(&output, 0);
                return 0;
  
                if (edit_branch_description(branch_name))
                        return 1;
+       } else if (copy) {
+               if (!argc)
+                       die(_("branch name required"));
+               else if (argc == 1)
+                       copy_or_rename_branch(head, argv[0], 1, copy > 1);
+               else if (argc == 2)
+                       copy_or_rename_branch(argv[0], argv[1], 1, copy > 1);
+               else
+                       die(_("too many branches for a copy operation"));
        } else if (rename) {
                if (!argc)
                        die(_("branch name required"));
                else if (argc == 1)
-                       rename_branch(head, argv[0], rename > 1);
+                       copy_or_rename_branch(head, argv[0], 0, rename > 1);
                else if (argc == 2)
-                       rename_branch(argv[0], argv[1], rename > 1);
+                       copy_or_rename_branch(argv[0], argv[1], 0, rename > 1);
                else
                        die(_("too many branches for a rename operation"));
        } else if (new_upstream) {
                strbuf_release(&buf);
        } else if (argc > 0 && argc <= 2) {
                struct branch *branch = branch_get(argv[0]);
 -              int branch_existed = 0, remote_tracking = 0;
 -              struct strbuf buf = STRBUF_INIT;
  
                if (!strcmp(argv[0], "HEAD"))
                        die(_("it does not make sense to create 'HEAD' manually"));
                        die(_("-a and -r options to 'git branch' do not make sense with a branch name"));
  
                if (track == BRANCH_TRACK_OVERRIDE)
 -                      fprintf(stderr, _("The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to\n"));
 -
 -              strbuf_addf(&buf, "refs/remotes/%s", branch->name);
 -              remote_tracking = ref_exists(buf.buf);
 -              strbuf_release(&buf);
 +                      die(_("the '--set-upstream' option is no longer supported. Please use '--track' or '--set-upstream-to' instead."));
  
 -              branch_existed = ref_exists(branch->refname);
                create_branch(argv[0], (argc == 2) ? argv[1] : head,
                              force, reflog, 0, quiet, track);
  
 -              /*
 -               * We only show the instructions if the user gave us
 -               * one branch which doesn't exist locally, but is the
 -               * name of a remote-tracking branch.
 -               */
 -              if (argc == 1 && track == BRANCH_TRACK_OVERRIDE &&
 -                  !branch_existed && remote_tracking) {
 -                      fprintf(stderr, _("\nIf you wanted to make '%s' track '%s', do this:\n\n"), head, branch->name);
 -                      fprintf(stderr, "    git branch -d %s\n", branch->name);
 -                      fprintf(stderr, "    git branch --set-upstream-to %s\n", branch->name);
 -              }
 -
        } else
                usage_with_options(builtin_branch_usage, options);
  
diff --combined config.c
index 345d78c2ba80bbb44c1b700605391ef09d2b3c42,d0d5aa1dc59110e22150700103a5bd2c684937b8..4831c1273542706437139ccc379afb38e7ca3d3b
+++ b/config.c
@@@ -6,8 -6,6 +6,8 @@@
   *
   */
  #include "cache.h"
 +#include "config.h"
 +#include "repository.h"
  #include "lockfile.h"
  #include "exec_cmd.h"
  #include "strbuf.h"
@@@ -16,7 -14,6 +16,7 @@@
  #include "string-list.h"
  #include "utf8.h"
  #include "dir.h"
 +#include "color.h"
  
  struct config_source {
        struct config_source *prev;
@@@ -74,6 -71,13 +74,6 @@@ static int core_compression_seen
  static int pack_compression_seen;
  static int zlib_compression_seen;
  
 -/*
 - * Default config_set that contains key-value pairs from the usual set of config
 - * config files (i.e repo specific .git/config, user wide ~/.gitconfig, XDG
 - * config file and the global /etc/gitconfig)
 - */
 -static struct config_set the_config_set;
 -
  static int config_file_fgetc(struct config_source *conf)
  {
        return getc_unlocked(conf->u.file);
@@@ -214,6 -218,8 +214,6 @@@ static int include_by_gitdir(const stru
  
        if (opts->git_dir)
                git_dir = opts->git_dir;
 -      else if (have_git_dir())
 -              git_dir = get_git_dir();
        else
                goto done;
  
@@@ -239,7 -245,7 +239,7 @@@ again
        }
  
        ret = !wildmatch(pattern.buf + prefix, text.buf + prefix,
 -                       icase ? WM_CASEFOLD : 0, NULL);
 +                       icase ? WM_CASEFOLD : 0);
  
        if (!ret && !already_tried_absolute) {
                /*
@@@ -389,7 -395,8 +389,7 @@@ static int git_config_parse_key_1(cons
  
  out_free_ret_1:
        if (store_key) {
 -              free(*store_key);
 -              *store_key = NULL;
 +              FREE_AND_NULL(*store_key);
        }
        return -CONFIG_INVALID_KEY;
  }
@@@ -597,8 -604,7 +597,8 @@@ static int get_value(config_fn_t fn, vo
         */
        cf->linenr--;
        ret = fn(name->buf, value, data);
 -      cf->linenr++;
 +      if (ret >= 0)
 +              cf->linenr++;
        return ret;
  }
  
@@@ -929,7 -935,7 +929,7 @@@ ssize_t git_config_ssize_t(const char *
        return ret;
  }
  
 -int git_parse_maybe_bool(const char *value)
 +static int git_parse_maybe_bool_text(const char *value)
  {
        if (!value)
                return 1;
        return -1;
  }
  
 -int git_config_maybe_bool(const char *name, const char *value)
 +int git_parse_maybe_bool(const char *value)
  {
 -      int v = git_parse_maybe_bool(value);
 +      int v = git_parse_maybe_bool_text(value);
        if (0 <= v)
                return v;
        if (git_parse_int(value, &v))
  
  int git_config_bool_or_int(const char *name, const char *value, int *is_bool)
  {
 -      int v = git_parse_maybe_bool(value);
 +      int v = git_parse_maybe_bool_text(value);
        if (0 <= v) {
                *is_bool = 1;
                return v;
@@@ -1351,9 -1357,6 +1351,9 @@@ int git_default_config(const char *var
        if (starts_with(var, "advice."))
                return git_default_advice_config(var, value);
  
 +      if (git_color_config(var, value, dummy) < 0)
 +              return -1;
 +
        if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
                pager_use_color = git_config_bool(var,value);
                return 0;
@@@ -1435,7 -1438,7 +1435,7 @@@ int git_config_from_file(config_fn_t fn
        int ret = -1;
        FILE *f;
  
 -      f = fopen(filename, "r");
 +      f = fopen_or_warn(filename, "r");
        if (f) {
                flockfile(f);
                ret = do_config_from_file(fn, CONFIG_ORIGIN_FILE, filename, filename, f, data);
@@@ -1464,9 -1467,9 +1464,9 @@@ int git_config_from_mem(config_fn_t fn
        return do_config_from(&top, fn, data);
  }
  
 -int git_config_from_blob_sha1(config_fn_t fn,
 +int git_config_from_blob_oid(config_fn_t fn,
                              const char *name,
 -                            const unsigned char *sha1,
 +                            const struct object_id *oid,
                              void *data)
  {
        enum object_type type;
        unsigned long size;
        int ret;
  
 -      buf = read_sha1_file(sha1, &type, &size);
 +      buf = read_sha1_file(oid->hash, &type, &size);
        if (!buf)
                return error("unable to load config blob object '%s'", name);
        if (type != OBJ_BLOB) {
@@@ -1492,11 -1495,11 +1492,11 @@@ static int git_config_from_blob_ref(con
                                    const char *name,
                                    void *data)
  {
 -      unsigned char sha1[20];
 +      struct object_id oid;
  
 -      if (get_sha1(name, sha1) < 0)
 +      if (get_oid(name, &oid) < 0)
                return error("unable to resolve config blob '%s'", name);
 -      return git_config_from_blob_sha1(fn, name, sha1, data);
 +      return git_config_from_blob_oid(fn, name, &oid, data);
  }
  
  const char *git_etc_gitconfig(void)
@@@ -1542,8 -1545,10 +1542,8 @@@ static int do_git_config_sequence(cons
        char *user_config = expand_user_path("~/.gitconfig", 0);
        char *repo_config;
  
 -      if (opts->git_dir)
 -              repo_config = mkpathdup("%s/config", opts->git_dir);
 -      else if (have_git_dir())
 -              repo_config = git_pathdup("config");
 +      if (opts->commondir)
 +              repo_config = mkpathdup("%s/config", opts->commondir);
        else
                repo_config = NULL;
  
        return ret;
  }
  
 -int git_config_with_options(config_fn_t fn, void *data,
 -                          struct git_config_source *config_source,
 -                          const struct config_options *opts)
 +int config_with_options(config_fn_t fn, void *data,
 +                      struct git_config_source *config_source,
 +                      const struct config_options *opts)
  {
        struct config_include_data inc = CONFIG_INCLUDE_INIT;
  
        return do_git_config_sequence(opts, fn, data);
  }
  
 -static void git_config_raw(config_fn_t fn, void *data)
 -{
 -      struct config_options opts = {0};
 -
 -      opts.respect_includes = 1;
 -      if (git_config_with_options(fn, data, NULL, &opts) < 0)
 -              /*
 -               * git_config_with_options() normally returns only
 -               * zero, as most errors are fatal, and
 -               * non-fatal potential errors are guarded by "if"
 -               * statements that are entered only when no error is
 -               * possible.
 -               *
 -               * If we ever encounter a non-fatal error, it means
 -               * something went really wrong and we should stop
 -               * immediately.
 -               */
 -              die(_("unknown error occurred while reading the configuration files"));
 -}
 -
  static void configset_iter(struct config_set *cs, config_fn_t fn, void *data)
  {
        int i, value_index;
  void read_early_config(config_fn_t cb, void *data)
  {
        struct config_options opts = {0};
 -      struct strbuf buf = STRBUF_INIT;
 +      struct strbuf commondir = STRBUF_INIT;
 +      struct strbuf gitdir = STRBUF_INIT;
  
        opts.respect_includes = 1;
  
 -      if (have_git_dir())
 +      if (have_git_dir()) {
 +              opts.commondir = get_git_common_dir();
                opts.git_dir = get_git_dir();
        /*
         * When setup_git_directory() was not yet asked to discover the
         * notably, the current working directory is still the same after the
         * call).
         */
 -      else if (discover_git_directory(&buf))
 -              opts.git_dir = buf.buf;
 -
 -      git_config_with_options(cb, data, NULL, &opts);
 -
 -      strbuf_release(&buf);
 -}
 +      } else if (!discover_git_directory(&commondir, &gitdir)) {
 +              opts.commondir = commondir.buf;
 +              opts.git_dir = gitdir.buf;
 +      }
  
 -static void git_config_check_init(void);
 +      config_with_options(cb, data, NULL, &opts);
  
 -void git_config(config_fn_t fn, void *data)
 -{
 -      git_config_check_init();
 -      configset_iter(&the_config_set, fn, data);
 +      strbuf_release(&commondir);
 +      strbuf_release(&gitdir);
  }
  
  static struct config_set_element *configset_find_element(struct config_set *cs, const char *key)
@@@ -1718,20 -1746,15 +1718,20 @@@ static int configset_add_value(struct c
        return 0;
  }
  
 -static int config_set_element_cmp(const struct config_set_element *e1,
 -                               const struct config_set_element *e2, const void *unused)
 +static int config_set_element_cmp(const void *unused_cmp_data,
 +                                const void *entry,
 +                                const void *entry_or_key,
 +                                const void *unused_keydata)
  {
 +      const struct config_set_element *e1 = entry;
 +      const struct config_set_element *e2 = entry_or_key;
 +
        return strcmp(e1->key, e2->key);
  }
  
  void git_configset_init(struct config_set *cs)
  {
 -      hashmap_init(&cs->config_hash, (hashmap_cmp_fn)config_set_element_cmp, 0);
 +      hashmap_init(&cs->config_hash, config_set_element_cmp, NULL, 0);
        cs->hash_initialized = 1;
        cs->list.nr = 0;
        cs->list.alloc = 0;
@@@ -1852,7 -1875,7 +1852,7 @@@ int git_configset_get_maybe_bool(struc
  {
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
 -              *dest = git_config_maybe_bool(key, value);
 +              *dest = git_parse_maybe_bool(value);
                if (*dest == -1)
                        return -1;
                return 0;
@@@ -1869,211 -1892,87 +1869,211 @@@ int git_configset_get_pathname(struct c
                return 1;
  }
  
 -static void git_config_check_init(void)
 +/* Functions use to read configuration from a repository */
 +static void repo_read_config(struct repository *repo)
  {
 -      if (the_config_set.hash_initialized)
 +      struct config_options opts;
 +
 +      opts.respect_includes = 1;
 +      opts.commondir = repo->commondir;
 +      opts.git_dir = repo->gitdir;
 +
 +      if (!repo->config)
 +              repo->config = xcalloc(1, sizeof(struct config_set));
 +      else
 +              git_configset_clear(repo->config);
 +
 +      git_configset_init(repo->config);
 +
 +      if (config_with_options(config_set_callback, repo->config, NULL, &opts) < 0)
 +              /*
 +               * config_with_options() normally returns only
 +               * zero, as most errors are fatal, and
 +               * non-fatal potential errors are guarded by "if"
 +               * statements that are entered only when no error is
 +               * possible.
 +               *
 +               * If we ever encounter a non-fatal error, it means
 +               * something went really wrong and we should stop
 +               * immediately.
 +               */
 +              die(_("unknown error occurred while reading the configuration files"));
 +}
 +
 +static void git_config_check_init(struct repository *repo)
 +{
 +      if (repo->config && repo->config->hash_initialized)
                return;
 -      git_configset_init(&the_config_set);
 -      git_config_raw(config_set_callback, &the_config_set);
 +      repo_read_config(repo);
  }
  
 -void git_config_clear(void)
 +static void repo_config_clear(struct repository *repo)
  {
 -      if (!the_config_set.hash_initialized)
 +      if (!repo->config || !repo->config->hash_initialized)
                return;
 -      git_configset_clear(&the_config_set);
 +      git_configset_clear(repo->config);
  }
  
 -int git_config_get_value(const char *key, const char **value)
 +void repo_config(struct repository *repo, config_fn_t fn, void *data)
  {
 -      git_config_check_init();
 -      return git_configset_get_value(&the_config_set, key, value);
 +      git_config_check_init(repo);
 +      configset_iter(repo->config, fn, data);
  }
  
 -const struct string_list *git_config_get_value_multi(const char *key)
 +int repo_config_get_value(struct repository *repo,
 +                        const char *key, const char **value)
  {
 -      git_config_check_init();
 -      return git_configset_get_value_multi(&the_config_set, key);
 +      git_config_check_init(repo);
 +      return git_configset_get_value(repo->config, key, value);
  }
  
 -int git_config_get_string_const(const char *key, const char **dest)
 +const struct string_list *repo_config_get_value_multi(struct repository *repo,
 +                                                    const char *key)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_value_multi(repo->config, key);
 +}
 +
 +int repo_config_get_string_const(struct repository *repo,
 +                               const char *key, const char **dest)
  {
        int ret;
 -      git_config_check_init();
 -      ret = git_configset_get_string_const(&the_config_set, key, dest);
 +      git_config_check_init(repo);
 +      ret = git_configset_get_string_const(repo->config, key, dest);
        if (ret < 0)
                git_die_config(key, NULL);
        return ret;
  }
  
 +int repo_config_get_string(struct repository *repo,
 +                         const char *key, char **dest)
 +{
 +      git_config_check_init(repo);
 +      return repo_config_get_string_const(repo, key, (const char **)dest);
 +}
 +
 +int repo_config_get_int(struct repository *repo,
 +                      const char *key, int *dest)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_int(repo->config, key, dest);
 +}
 +
 +int repo_config_get_ulong(struct repository *repo,
 +                        const char *key, unsigned long *dest)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_ulong(repo->config, key, dest);
 +}
 +
 +int repo_config_get_bool(struct repository *repo,
 +                       const char *key, int *dest)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_bool(repo->config, key, dest);
 +}
 +
 +int repo_config_get_bool_or_int(struct repository *repo,
 +                              const char *key, int *is_bool, int *dest)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_bool_or_int(repo->config, key, is_bool, dest);
 +}
 +
 +int repo_config_get_maybe_bool(struct repository *repo,
 +                             const char *key, int *dest)
 +{
 +      git_config_check_init(repo);
 +      return git_configset_get_maybe_bool(repo->config, key, dest);
 +}
 +
 +int repo_config_get_pathname(struct repository *repo,
 +                           const char *key, const char **dest)
 +{
 +      int ret;
 +      git_config_check_init(repo);
 +      ret = git_configset_get_pathname(repo->config, key, dest);
 +      if (ret < 0)
 +              git_die_config(key, NULL);
 +      return ret;
 +}
 +
 +/* Functions used historically to read configuration from 'the_repository' */
 +void git_config(config_fn_t fn, void *data)
 +{
 +      repo_config(the_repository, fn, data);
 +}
 +
 +void git_config_clear(void)
 +{
 +      repo_config_clear(the_repository);
 +}
 +
 +int git_config_get_value(const char *key, const char **value)
 +{
 +      return repo_config_get_value(the_repository, key, value);
 +}
 +
 +const struct string_list *git_config_get_value_multi(const char *key)
 +{
 +      return repo_config_get_value_multi(the_repository, key);
 +}
 +
 +int git_config_get_string_const(const char *key, const char **dest)
 +{
 +      return repo_config_get_string_const(the_repository, key, dest);
 +}
 +
  int git_config_get_string(const char *key, char **dest)
  {
 -      git_config_check_init();
 -      return git_config_get_string_const(key, (const char **)dest);
 +      return repo_config_get_string(the_repository, key, dest);
  }
  
  int git_config_get_int(const char *key, int *dest)
  {
 -      git_config_check_init();
 -      return git_configset_get_int(&the_config_set, key, dest);
 +      return repo_config_get_int(the_repository, key, dest);
  }
  
  int git_config_get_ulong(const char *key, unsigned long *dest)
  {
 -      git_config_check_init();
 -      return git_configset_get_ulong(&the_config_set, key, dest);
 +      return repo_config_get_ulong(the_repository, key, dest);
  }
  
  int git_config_get_bool(const char *key, int *dest)
  {
 -      git_config_check_init();
 -      return git_configset_get_bool(&the_config_set, key, dest);
 +      return repo_config_get_bool(the_repository, key, dest);
  }
  
  int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest)
  {
 -      git_config_check_init();
 -      return git_configset_get_bool_or_int(&the_config_set, key, is_bool, dest);
 +      return repo_config_get_bool_or_int(the_repository, key, is_bool, dest);
  }
  
  int git_config_get_maybe_bool(const char *key, int *dest)
  {
 -      git_config_check_init();
 -      return git_configset_get_maybe_bool(&the_config_set, key, dest);
 +      return repo_config_get_maybe_bool(the_repository, key, dest);
  }
  
  int git_config_get_pathname(const char *key, const char **dest)
  {
 -      int ret;
 -      git_config_check_init();
 -      ret = git_configset_get_pathname(&the_config_set, key, dest);
 -      if (ret < 0)
 -              git_die_config(key, NULL);
 -      return ret;
 +      return repo_config_get_pathname(the_repository, key, dest);
 +}
 +
 +/*
 + * Note: This function exists solely to maintain backward compatibility with
 + * 'fetch' and 'update_clone' storing configuration in '.gitmodules' and should
 + * NOT be used anywhere else.
 + *
 + * Runs the provided config function on the '.gitmodules' file found in the
 + * working directory.
 + */
 +void config_from_gitmodules(config_fn_t fn, void *data)
 +{
 +      if (the_repository->worktree) {
 +              char *file = repo_worktree_path(the_repository, GITMODULES_FILE);
 +              git_config_from_file(fn, file, data);
 +              free(file);
 +      }
  }
  
  int git_config_get_expiry(const char *key, const char **output)
        return ret;
  }
  
 +int git_config_get_expiry_in_days(const char *key, timestamp_t *expiry, timestamp_t now)
 +{
 +      char *expiry_string;
 +      intmax_t days;
 +      timestamp_t when;
 +
 +      if (git_config_get_string(key, &expiry_string))
 +              return 1; /* no such thing */
 +
 +      if (git_parse_signed(expiry_string, &days, maximum_signed_value_of_type(int))) {
 +              const int scale = 86400;
 +              *expiry = now - days * scale;
 +              return 0;
 +      }
 +
 +      if (!parse_expiry_date(expiry_string, &when)) {
 +              *expiry = when;
 +              return 0;
 +      }
 +      return -1; /* thing exists but cannot be parsed */
 +}
 +
  int git_config_get_untracked_cache(void)
  {
        int val = -1;
@@@ -2200,7 -2077,7 +2200,7 @@@ static struct 
        size_t *offset;
        unsigned int offset_alloc;
        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 -      int seen;
 +      unsigned int seen;
  } store;
  
  static int matches(const char *key, const char *value)
@@@ -2292,11 -2169,10 +2292,10 @@@ static int write_error(const char *file
        return 4;
  }
  
- static ssize_t write_section(int fd, const char *key)
+ static struct strbuf store_create_section(const char *key)
  {
        const char *dot;
        int i;
-       ssize_t ret;
        struct strbuf sb = STRBUF_INIT;
  
        dot = memchr(key, '.', store.baselen);
                strbuf_addf(&sb, "[%.*s]\n", store.baselen, key);
        }
  
-       ret = write_in_full(fd, sb.buf, sb.len);
+       return sb;
+ }
 -static int store_write_section(int fd, const char *key)
++static ssize_t write_section(int fd, const char *key)
+ {
 -      int success;
 -
+       struct strbuf sb = store_create_section(key);
++      ssize_t ret;
 -      success = write_in_full(fd, sb.buf, sb.len) == sb.len;
++      ret = write_in_full(fd, sb.buf, sb.len) == sb.len;
        strbuf_release(&sb);
  
 -      return success;
 +      return ret;
  }
  
 -static int store_write_pair(int fd, const char *key, const char *value)
 +static ssize_t write_pair(int fd, const char *key, const char *value)
  {
 -      int i, success;
 +      int i;
 +      ssize_t ret;
        int length = strlen(key + store.baselen + 1);
        const char *quote = "";
        struct strbuf sb = STRBUF_INIT;
                case '"':
                case '\\':
                        strbuf_addch(&sb, '\\');
 +                      /* fallthrough */
                default:
                        strbuf_addch(&sb, value[i]);
                        break;
                }
        strbuf_addf(&sb, "%s\n", quote);
  
 -      success = write_in_full(fd, sb.buf, sb.len) == sb.len;
 +      ret = write_in_full(fd, sb.buf, sb.len);
        strbuf_release(&sb);
  
 -      return success;
 +      return ret;
  }
  
  static ssize_t find_beginning_of_line(const char *contents, size_t size,
@@@ -2448,7 -2331,7 +2455,7 @@@ int git_config_set_multivar_in_file_gen
  {
        int fd = -1, in_fd = -1;
        int ret;
 -      struct lock_file *lock = NULL;
 +      struct lock_file lock = LOCK_INIT;
        char *filename_buf = NULL;
        char *contents = NULL;
        size_t contents_sz;
         * The lock serves a purpose in addition to locking: the new
         * contents of .git/config will be written into it.
         */
 -      lock = xcalloc(1, sizeof(struct lock_file));
 -      fd = hold_lock_file_for_update(lock, config_filename, 0);
 +      fd = hold_lock_file_for_update(&lock, config_filename, 0);
        if (fd < 0) {
                error_errno("could not lock config file %s", config_filename);
                free(store.key);
                }
  
                store.key = (char *)key;
 -              if (!store_write_section(fd, key) ||
 -                  !store_write_pair(fd, key, value))
 +              if (write_section(fd, key) < 0 ||
 +                  write_pair(fd, key, value) < 0)
                        goto write_err_out;
        } else {
                struct stat st;
                close(in_fd);
                in_fd = -1;
  
 -              if (chmod(get_lock_file_path(lock), st.st_mode & 07777) < 0) {
 -                      error_errno("chmod on %s failed", get_lock_file_path(lock));
 +              if (chmod(get_lock_file_path(&lock), st.st_mode & 07777) < 0) {
 +                      error_errno("chmod on %s failed", get_lock_file_path(&lock));
                        ret = CONFIG_NO_WRITE;
                        goto out_free;
                }
                        /* write the first part of the config */
                        if (copy_end > copy_begin) {
                                if (write_in_full(fd, contents + copy_begin,
 -                                                copy_end - copy_begin) <
 -                                  copy_end - copy_begin)
 +                                                copy_end - copy_begin) < 0)
                                        goto write_err_out;
                                if (new_line &&
 -                                  write_str_in_full(fd, "\n") != 1)
 +                                  write_str_in_full(fd, "\n") < 0)
                                        goto write_err_out;
                        }
                        copy_begin = store.offset[i];
                /* write the pair (value == NULL means unset) */
                if (value != NULL) {
                        if (store.state == START) {
 -                              if (!store_write_section(fd, key))
 +                              if (write_section(fd, key) < 0)
                                        goto write_err_out;
                        }
 -                      if (!store_write_pair(fd, key, value))
 +                      if (write_pair(fd, key, value) < 0)
                                goto write_err_out;
                }
  
                /* write the rest of the config */
                if (copy_begin < contents_sz)
                        if (write_in_full(fd, contents + copy_begin,
 -                                        contents_sz - copy_begin) <
 -                          contents_sz - copy_begin)
 +                                        contents_sz - copy_begin) < 0)
                                goto write_err_out;
  
                munmap(contents, contents_sz);
                contents = NULL;
        }
  
 -      if (commit_lock_file(lock) < 0) {
 +      if (commit_lock_file(&lock) < 0) {
                error_errno("could not write config file %s", config_filename);
                ret = CONFIG_NO_WRITE;
 -              lock = NULL;
                goto out_free;
        }
  
 -      /*
 -       * lock is committed, so don't try to roll it back below.
 -       * NOTE: Since lockfile.c keeps a linked list of all created
 -       * lock_file structures, it isn't safe to free(lock).  It's
 -       * better to just leave it hanging around.
 -       */
 -      lock = NULL;
        ret = 0;
  
        /* Invalidate the config cache */
        git_config_clear();
  
  out_free:
 -      if (lock)
 -              rollback_lock_file(lock);
 +      rollback_lock_file(&lock);
        free(filename_buf);
        if (contents)
                munmap(contents, contents_sz);
        return ret;
  
  write_err_out:
 -      ret = write_error(get_lock_file_path(lock));
 +      ret = write_error(get_lock_file_path(&lock));
        goto out_free;
  
  }
@@@ -2743,8 -2638,8 +2750,8 @@@ static int section_name_is_ok(const cha
  }
  
  /* if new_name == NULL, the section is removed instead */
int git_config_rename_section_in_file(const char *config_filename,
-                                     const char *old_name, const char *new_name)
static int git_config_copy_or_rename_section_in_file(const char *config_filename,
+                                     const char *old_name, const char *new_name, int copy)
  {
        int ret = 0, remove = 0;
        char *filename_buf = NULL;
        char buf[1024];
        FILE *config_file = NULL;
        struct stat st;
+       struct strbuf copystr = STRBUF_INIT;
  
        if (new_name && !section_name_is_ok(new_name)) {
                ret = error("invalid section name: %s", new_name);
        }
  
        if (!(config_file = fopen(config_filename, "rb"))) {
 +              ret = warn_on_fopen_errors(config_filename);
 +              if (ret)
 +                      goto out;
                /* no config file means nothing to rename, no error */
                goto commit_and_out;
        }
        while (fgets(buf, sizeof(buf), config_file)) {
                int i;
                int length;
+               int is_section = 0;
                char *output = buf;
                for (i = 0; buf[i] && isspace(buf[i]); i++)
                        ; /* do nothing */
                if (buf[i] == '[') {
                        /* it's a section */
-                       int offset = section_name_match(&buf[i], old_name);
+                       int offset;
+                       is_section = 1;
+                       /*
+                        * When encountering a new section under -c we
+                        * need to flush out any section we're already
+                        * coping and begin anew. There might be
+                        * multiple [branch "$name"] sections.
+                        */
+                       if (copystr.len > 0) {
+                               if (write_in_full(out_fd, copystr.buf, copystr.len) != copystr.len) {
+                                       ret = write_error(get_lock_file_path(lock));
+                                       goto out;
+                               }
+                               strbuf_reset(&copystr);
+                       }
+                       offset = section_name_match(&buf[i], old_name);
                        if (offset > 0) {
                                ret++;
                                if (new_name == NULL) {
                                        continue;
                                }
                                store.baselen = strlen(new_name);
-                               if (write_section(out_fd, new_name) < 0) {
-                                       ret = write_error(get_lock_file_path(lock));
-                                       goto out;
-                               }
-                               /*
-                                * We wrote out the new section, with
-                                * a newline, now skip the old
-                                * section's length
-                                */
-                               output += offset + i;
-                               if (strlen(output) > 0) {
+                               if (!copy) {
 -                                      if (!store_write_section(out_fd, new_name)) {
++                                      if (write_section(out_fd, new_name) < 0) {
+                                               ret = write_error(get_lock_file_path(lock));
+                                               goto out;
+                                       }
 -
                                        /*
-                                        * More content means there's
-                                        * a declaration to put on the
-                                        * next line; indent with a
-                                        * tab
+                                        * We wrote out the new section, with
+                                        * a newline, now skip the old
+                                        * section's length
                                         */
-                                       output -= 1;
-                                       output[0] = '\t';
+                                       output += offset + i;
+                                       if (strlen(output) > 0) {
+                                               /*
+                                                * More content means there's
+                                                * a declaration to put on the
+                                                * next line; indent with a
+                                                * tab
+                                                */
+                                               output -= 1;
+                                               output[0] = '\t';
+                                       }
+                               } else {
+                                       copystr = store_create_section(new_name);
                                }
                        }
                        remove = 0;
                if (remove)
                        continue;
                length = strlen(output);
 -              if (write_in_full(out_fd, output, length) != length) {
+               if (!is_section && copystr.len > 0) {
+                       strbuf_add(&copystr, output, length);
+               }
 +              if (write_in_full(out_fd, output, length) < 0) {
                        ret = write_error(get_lock_file_path(lock));
                        goto out;
                }
        }
+       /*
+        * Copy a trailing section at the end of the config, won't be
+        * flushed by the usual "flush because we have a new section
+        * logic in the loop above.
+        */
+       if (copystr.len > 0) {
+               if (write_in_full(out_fd, copystr.buf, copystr.len) != copystr.len) {
+                       ret = write_error(get_lock_file_path(lock));
+                       goto out;
+               }
+               strbuf_reset(&copystr);
+       }
        fclose(config_file);
        config_file = NULL;
  commit_and_out:
@@@ -2850,11 -2785,30 +2899,30 @@@ out_no_rollback
        return ret;
  }
  
+ int git_config_rename_section_in_file(const char *config_filename,
+                                     const char *old_name, const char *new_name)
+ {
+       return git_config_copy_or_rename_section_in_file(config_filename,
+                                        old_name, new_name, 0);
+ }
  int git_config_rename_section(const char *old_name, const char *new_name)
  {
        return git_config_rename_section_in_file(NULL, old_name, new_name);
  }
  
+ int git_config_copy_section_in_file(const char *config_filename,
+                                     const char *old_name, const char *new_name)
+ {
+       return git_config_copy_or_rename_section_in_file(config_filename,
+                                        old_name, new_name, 1);
+ }
+ int git_config_copy_section(const char *old_name, const char *new_name)
+ {
+       return git_config_copy_section_in_file(NULL, old_name, new_name);
+ }
  /*
   * Call this to report error for your variable that should not
   * get a boolean value (i.e. "[my] var" means "true").
diff --combined config.h
index 456b3d134d3ed187b80b5941c20690763f3eab35,0000000000000000000000000000000000000000..a49d26441622508fd3c6560ac9784e84541c10dc
mode 100644,000000..100644
--- /dev/null
+++ b/config.h
@@@ -1,230 -1,0 +1,232 @@@
 +#ifndef CONFIG_H
 +#define CONFIG_H
 +
 +/* git_config_parse_key() returns these negated: */
 +#define CONFIG_INVALID_KEY 1
 +#define CONFIG_NO_SECTION_OR_NAME 2
 +/* git_config_set_gently(), git_config_set_multivar_gently() return the above or these: */
 +#define CONFIG_NO_LOCK -1
 +#define CONFIG_INVALID_FILE 3
 +#define CONFIG_NO_WRITE 4
 +#define CONFIG_NOTHING_SET 5
 +#define CONFIG_INVALID_PATTERN 6
 +#define CONFIG_GENERIC_ERROR 7
 +
 +#define CONFIG_REGEX_NONE ((void *)1)
 +
 +struct git_config_source {
 +      unsigned int use_stdin:1;
 +      const char *file;
 +      const char *blob;
 +};
 +
 +enum config_origin_type {
 +      CONFIG_ORIGIN_BLOB,
 +      CONFIG_ORIGIN_FILE,
 +      CONFIG_ORIGIN_STDIN,
 +      CONFIG_ORIGIN_SUBMODULE_BLOB,
 +      CONFIG_ORIGIN_CMDLINE
 +};
 +
 +struct config_options {
 +      unsigned int respect_includes : 1;
 +      const char *commondir;
 +      const char *git_dir;
 +};
 +
 +typedef int (*config_fn_t)(const char *, const char *, void *);
 +extern int git_default_config(const char *, const char *, void *);
 +extern int git_config_from_file(config_fn_t fn, const char *, void *);
 +extern int git_config_from_mem(config_fn_t fn, const enum config_origin_type,
 +                                      const char *name, const char *buf, size_t len, void *data);
 +extern int git_config_from_blob_oid(config_fn_t fn, const char *name,
 +                                  const struct object_id *oid, void *data);
 +extern void git_config_push_parameter(const char *text);
 +extern int git_config_from_parameters(config_fn_t fn, void *data);
 +extern void read_early_config(config_fn_t cb, void *data);
 +extern void git_config(config_fn_t fn, void *);
 +extern int config_with_options(config_fn_t fn, void *,
 +                             struct git_config_source *config_source,
 +                             const struct config_options *opts);
 +extern int git_parse_ulong(const char *, unsigned long *);
 +extern int git_parse_maybe_bool(const char *);
 +extern int git_config_int(const char *, const char *);
 +extern int64_t git_config_int64(const char *, const char *);
 +extern unsigned long git_config_ulong(const char *, const char *);
 +extern ssize_t git_config_ssize_t(const char *, const char *);
 +extern int git_config_bool_or_int(const char *, const char *, int *);
 +extern int git_config_bool(const char *, const char *);
 +extern int git_config_string(const char **, const char *, const char *);
 +extern int git_config_pathname(const char **, const char *, const char *);
 +extern int git_config_set_in_file_gently(const char *, const char *, const char *);
 +extern void git_config_set_in_file(const char *, const char *, const char *);
 +extern int git_config_set_gently(const char *, const char *);
 +extern void git_config_set(const char *, const char *);
 +extern int git_config_parse_key(const char *, char **, int *);
 +extern int git_config_key_is_valid(const char *key);
 +extern int git_config_set_multivar_gently(const char *, const char *, const char *, int);
 +extern void git_config_set_multivar(const char *, const char *, const char *, int);
 +extern int git_config_set_multivar_in_file_gently(const char *, const char *, const char *, const char *, int);
 +extern void git_config_set_multivar_in_file(const char *, const char *, const char *, const char *, int);
 +extern int git_config_rename_section(const char *, const char *);
 +extern int git_config_rename_section_in_file(const char *, const char *, const char *);
++extern int git_config_copy_section(const char *, const char *);
++extern int git_config_copy_section_in_file(const char *, const char *, const char *);
 +extern const char *git_etc_gitconfig(void);
 +extern int git_env_bool(const char *, int);
 +extern unsigned long git_env_ulong(const char *, unsigned long);
 +extern int git_config_system(void);
 +extern int config_error_nonbool(const char *);
 +#if defined(__GNUC__)
 +#define config_error_nonbool(s) (config_error_nonbool(s), const_error())
 +#endif
 +
 +extern int git_config_parse_parameter(const char *, config_fn_t fn, void *data);
 +
 +enum config_scope {
 +      CONFIG_SCOPE_UNKNOWN = 0,
 +      CONFIG_SCOPE_SYSTEM,
 +      CONFIG_SCOPE_GLOBAL,
 +      CONFIG_SCOPE_REPO,
 +      CONFIG_SCOPE_CMDLINE,
 +};
 +
 +extern enum config_scope current_config_scope(void);
 +extern const char *current_config_origin_type(void);
 +extern const char *current_config_name(void);
 +
 +struct config_include_data {
 +      int depth;
 +      config_fn_t fn;
 +      void *data;
 +      const struct config_options *opts;
 +};
 +#define CONFIG_INCLUDE_INIT { 0 }
 +extern int git_config_include(const char *name, const char *value, void *data);
 +
 +/*
 + * Match and parse a config key of the form:
 + *
 + *   section.(subsection.)?key
 + *
 + * (i.e., what gets handed to a config_fn_t). The caller provides the section;
 + * we return -1 if it does not match, 0 otherwise. The subsection and key
 + * out-parameters are filled by the function (and *subsection is NULL if it is
 + * missing).
 + *
 + * If the subsection pointer-to-pointer passed in is NULL, returns 0 only if
 + * there is no subsection at all.
 + */
 +extern int parse_config_key(const char *var,
 +                          const char *section,
 +                          const char **subsection, int *subsection_len,
 +                          const char **key);
 +
 +struct config_set_element {
 +      struct hashmap_entry ent;
 +      char *key;
 +      struct string_list value_list;
 +};
 +
 +struct configset_list_item {
 +      struct config_set_element *e;
 +      int value_index;
 +};
 +
 +/*
 + * the contents of the list are ordered according to their
 + * position in the config files and order of parsing the files.
 + * (i.e. key-value pair at the last position of .git/config will
 + * be at the last item of the list)
 + */
 +struct configset_list {
 +      struct configset_list_item *items;
 +      unsigned int nr, alloc;
 +};
 +
 +struct config_set {
 +      struct hashmap config_hash;
 +      int hash_initialized;
 +      struct configset_list list;
 +};
 +
 +extern void git_configset_init(struct config_set *cs);
 +extern int git_configset_add_file(struct config_set *cs, const char *filename);
 +extern int git_configset_get_value(struct config_set *cs, const char *key, const char **value);
 +extern const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key);
 +extern void git_configset_clear(struct config_set *cs);
 +extern int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest);
 +extern int git_configset_get_string(struct config_set *cs, const char *key, char **dest);
 +extern int git_configset_get_int(struct config_set *cs, const char *key, int *dest);
 +extern int git_configset_get_ulong(struct config_set *cs, const char *key, unsigned long *dest);
 +extern int git_configset_get_bool(struct config_set *cs, const char *key, int *dest);
 +extern int git_configset_get_bool_or_int(struct config_set *cs, const char *key, int *is_bool, int *dest);
 +extern int git_configset_get_maybe_bool(struct config_set *cs, const char *key, int *dest);
 +extern int git_configset_get_pathname(struct config_set *cs, const char *key, const char **dest);
 +
 +/* Functions for reading a repository's config */
 +struct repository;
 +extern void repo_config(struct repository *repo, config_fn_t fn, void *data);
 +extern int repo_config_get_value(struct repository *repo,
 +                               const char *key, const char **value);
 +extern const struct string_list *repo_config_get_value_multi(struct repository *repo,
 +                                                           const char *key);
 +extern int repo_config_get_string_const(struct repository *repo,
 +                                      const char *key, const char **dest);
 +extern int repo_config_get_string(struct repository *repo,
 +                                const char *key, char **dest);
 +extern int repo_config_get_int(struct repository *repo,
 +                             const char *key, int *dest);
 +extern int repo_config_get_ulong(struct repository *repo,
 +                               const char *key, unsigned long *dest);
 +extern int repo_config_get_bool(struct repository *repo,
 +                              const char *key, int *dest);
 +extern int repo_config_get_bool_or_int(struct repository *repo,
 +                                     const char *key, int *is_bool, int *dest);
 +extern int repo_config_get_maybe_bool(struct repository *repo,
 +                                    const char *key, int *dest);
 +extern int repo_config_get_pathname(struct repository *repo,
 +                                  const char *key, const char **dest);
 +
 +/*
 + * Note: This function exists solely to maintain backward compatibility with
 + * 'fetch' and 'update_clone' storing configuration in '.gitmodules' and should
 + * NOT be used anywhere else.
 + *
 + * Runs the provided config function on the '.gitmodules' file found in the
 + * working directory.
 + */
 +extern void config_from_gitmodules(config_fn_t fn, void *data);
 +
 +extern int git_config_get_value(const char *key, const char **value);
 +extern const struct string_list *git_config_get_value_multi(const char *key);
 +extern void git_config_clear(void);
 +extern int git_config_get_string_const(const char *key, const char **dest);
 +extern int git_config_get_string(const char *key, char **dest);
 +extern int git_config_get_int(const char *key, int *dest);
 +extern int git_config_get_ulong(const char *key, unsigned long *dest);
 +extern int git_config_get_bool(const char *key, int *dest);
 +extern int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest);
 +extern int git_config_get_maybe_bool(const char *key, int *dest);
 +extern int git_config_get_pathname(const char *key, const char **dest);
 +extern int git_config_get_untracked_cache(void);
 +extern int git_config_get_split_index(void);
 +extern int git_config_get_max_percent_split_change(void);
 +
 +/* This dies if the configured or default date is in the future */
 +extern int git_config_get_expiry(const char *key, const char **output);
 +
 +/* parse either "this many days" integer, or "5.days.ago" approxidate */
 +extern int git_config_get_expiry_in_days(const char *key, timestamp_t *, timestamp_t now);
 +
 +struct key_value_info {
 +      const char *filename;
 +      int linenr;
 +      enum config_origin_type origin_type;
 +      enum config_scope scope;
 +};
 +
 +extern NORETURN void git_die_config(const char *key, const char *err, ...) __attribute__((format(printf, 2, 3)));
 +extern NORETURN void git_die_config_linenr(const char *key, const char *filename, int linenr);
 +
 +#endif /* CONFIG_H */
diff --combined refs.c
index 6042645c40614992bbd8ea0b06c53a350449f413,d724cda58f890a34ec09c7cb43743ff1dc7af063..6cfd88ff6b581e3d60c7f81e2e8d74dafee6fc84
--- 1/refs.c
--- 2/refs.c
+++ b/refs.c
@@@ -3,7 -3,6 +3,7 @@@
   */
  
  #include "cache.h"
 +#include "config.h"
  #include "hashmap.h"
  #include "lockfile.h"
  #include "iterator.h"
@@@ -174,24 -173,6 +174,24 @@@ int refname_is_safe(const char *refname
        return 1;
  }
  
 +/*
 + * Return true if refname, which has the specified oid and flags, can
 + * be resolved to an object in the database. If the referred-to object
 + * does not exist, emit a warning and return false.
 + */
 +int ref_resolves_to_object(const char *refname,
 +                         const struct object_id *oid,
 +                         unsigned int flags)
 +{
 +      if (flags & REF_ISBROKEN)
 +              return 0;
 +      if (!has_sha1_file(oid->hash)) {
 +              error("%s does not point to a valid object!", refname);
 +              return 0;
 +      }
 +      return 1;
 +}
 +
  char *refs_resolve_refdup(struct ref_store *refs,
                          const char *refname, int resolve_flags,
                          unsigned char *sha1, int *flags)
@@@ -239,7 -220,8 +239,7 @@@ int read_ref(const char *refname, unsig
  
  int ref_exists(const char *refname)
  {
 -      unsigned char sha1[20];
 -      return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 +      return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
  }
  
  static int filter_refs(const char *refname, const struct object_id *oid,
  {
        struct ref_filter *filter = (struct ref_filter *)data;
  
 -      if (wildmatch(filter->pattern, refname, 0, NULL))
 +      if (wildmatch(filter->pattern, refname, 0))
                return 0;
        return filter->fn(refname, oid, flags, filter->cb_data);
  }
@@@ -285,11 -267,12 +285,11 @@@ static int warn_if_dangling_symref(cons
  {
        struct warn_if_dangling_data *d = cb_data;
        const char *resolves_to;
 -      struct object_id junk;
  
        if (!(flags & REF_ISSYMREF))
                return 0;
  
 -      resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 +      resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
        if (!resolves_to
            || (d->refname
                ? strcmp(resolves_to, d->refname)
@@@ -334,6 -317,12 +334,6 @@@ int for_each_tag_ref(each_ref_fn fn, vo
        return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
  }
  
 -int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 -{
 -      return refs_for_each_tag_ref(get_submodule_ref_store(submodule),
 -                                   fn, cb_data);
 -}
 -
  int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
  {
        return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
@@@ -344,6 -333,12 +344,6 @@@ int for_each_branch_ref(each_ref_fn fn
        return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
  }
  
 -int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 -{
 -      return refs_for_each_branch_ref(get_submodule_ref_store(submodule),
 -                                      fn, cb_data);
 -}
 -
  int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
  {
        return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
@@@ -354,6 -349,12 +354,6 @@@ int for_each_remote_ref(each_ref_fn fn
        return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
  }
  
 -int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 -{
 -      return refs_for_each_remote_ref(get_submodule_ref_store(submodule),
 -                                      fn, cb_data);
 -}
 -
  int head_ref_namespaced(each_ref_fn fn, void *cb_data)
  {
        struct strbuf buf = STRBUF_INIT;
@@@ -559,21 -560,6 +559,21 @@@ enum ref_type ref_type(const char *refn
         return REF_TYPE_NORMAL;
  }
  
 +long get_files_ref_lock_timeout_ms(void)
 +{
 +      static int configured = 0;
 +
 +      /* The default timeout is 100 ms: */
 +      static int timeout_ms = 100;
 +
 +      if (!configured) {
 +              git_config_get_int("core.filesreflocktimeout", &timeout_ms);
 +              configured = 1;
 +      }
 +
 +      return timeout_ms;
 +}
 +
  static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
                           const unsigned char *old_sha1, struct strbuf *err)
  {
        strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
  
        filename = git_path("%s", pseudoref);
 -      fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 +      fd = hold_lock_file_for_update_timeout(&lock, filename,
 +                                             LOCK_DIE_ON_ERROR,
 +                                             get_files_ref_lock_timeout_ms());
        if (fd < 0) {
                strbuf_addf(err, "could not open '%s' for writing: %s",
                            filename, strerror(errno));
 -              return -1;
 +              goto done;
        }
  
        if (old_sha1) {
                }
        }
  
 -      if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 +      if (write_in_full(fd, buf.buf, buf.len) < 0) {
                strbuf_addf(err, "could not write to '%s'", filename);
                rollback_lock_file(&lock);
                goto done;
@@@ -631,9 -615,8 +631,9 @@@ static int delete_pseudoref(const char 
                int fd;
                unsigned char actual_old_sha1[20];
  
 -              fd = hold_lock_file_for_update(&lock, filename,
 -                                             LOCK_DIE_ON_ERROR);
 +              fd = hold_lock_file_for_update_timeout(
 +                              &lock, filename, LOCK_DIE_ON_ERROR,
 +                              get_files_ref_lock_timeout_ms());
                if (fd < 0)
                        die_errno(_("Could not open '%s' for writing"), filename);
                if (read_ref(pseudoref, actual_old_sha1))
@@@ -834,7 -817,7 +834,7 @@@ int read_ref_at(const char *refname, un
        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
  
        if (!cb.reccnt) {
 -              if (flags & GET_SHA1_QUIETLY)
 +              if (flags & GET_OID_QUIETLY)
                        exit(128);
                else
                        die("Log for %s is empty.", refname);
@@@ -937,8 -920,6 +937,8 @@@ int ref_transaction_update(struct ref_t
                return -1;
        }
  
 +      flags &= REF_TRANSACTION_UPDATE_ALLOWED_FLAGS;
 +
        flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
  
        ref_transaction_add_update(transaction, refname, flags,
@@@ -1178,7 -1159,7 +1178,7 @@@ int ref_is_hidden(const char *refname, 
                const char *match = hide_refs->items[i].string;
                const char *subject;
                int neg = 0;
 -              int len;
 +              const char *p;
  
                if (*match == '!') {
                        neg = 1;
                }
  
                /* refname can be NULL when namespaces are used. */
 -              if (!subject || !starts_with(subject, match))
 -                      continue;
 -              len = strlen(match);
 -              if (!subject[len] || subject[len] == '/')
 +              if (subject &&
 +                  skip_prefix(subject, match, &p) &&
 +                  (!*p || *p == '/'))
                        return !neg;
        }
        return 0;
@@@ -1248,13 -1230,19 +1248,13 @@@ int refs_rename_ref_available(struct re
        return ok;
  }
  
 -int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
  {
        struct object_id oid;
        int flag;
  
 -      if (submodule) {
 -              if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
 -                      return fn("HEAD", &oid, 0, cb_data);
 -
 -              return 0;
 -      }
 -
 -      if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
 +      if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
 +                              oid.hash, &flag))
                return fn("HEAD", &oid, flag, cb_data);
  
        return 0;
  
  int head_ref(each_ref_fn fn, void *cb_data)
  {
 -      return head_ref_submodule(NULL, fn, cb_data);
 +      return refs_head_ref(get_main_ref_store(), fn, cb_data);
  }
  
  struct ref_iterator *refs_ref_iterator_begin(
@@@ -1320,6 -1308,11 +1320,6 @@@ int for_each_ref(each_ref_fn fn, void *
        return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
  }
  
 -int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 -{
 -      return refs_for_each_ref(get_submodule_ref_store(submodule), fn, cb_data);
 -}
 -
  int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
                         each_ref_fn fn, void *cb_data)
  {
@@@ -1341,15 -1334,11 +1341,15 @@@ int for_each_fullref_in(const char *pre
                               prefix, fn, 0, flag, cb_data);
  }
  
 -int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 -                            each_ref_fn fn, void *cb_data)
 +int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
 +                           each_ref_fn fn, void *cb_data,
 +                           unsigned int broken)
  {
 -      return refs_for_each_ref_in(get_submodule_ref_store(submodule),
 -                                  prefix, fn, cb_data);
 +      unsigned int flag = 0;
 +
 +      if (broken)
 +              flag = DO_FOR_EACH_INCLUDE_BROKEN;
 +      return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
  }
  
  int for_each_replace_ref(each_ref_fn fn, void *cb_data)
        return do_for_each_ref(get_main_ref_store(),
                               git_replace_ref_base, fn,
                               strlen(git_replace_ref_base),
 -                             0, cb_data);
 +                             DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
  }
  
  int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
@@@ -1396,12 -1385,9 +1396,12 @@@ const char *refs_resolve_ref_unsafe(str
                                    unsigned char *sha1, int *flags)
  {
        static struct strbuf sb_refname = STRBUF_INIT;
 +      struct object_id unused_oid;
        int unused_flags;
        int symref_count;
  
 +      if (!sha1)
 +              sha1 = unused_oid.hash;
        if (!flags)
                flags = &unused_flags;
  
@@@ -1487,10 -1473,25 +1487,10 @@@ const char *resolve_ref_unsafe(const ch
  int resolve_gitlink_ref(const char *submodule, const char *refname,
                        unsigned char *sha1)
  {
 -      size_t len = strlen(submodule);
        struct ref_store *refs;
        int flags;
  
 -      while (len && submodule[len - 1] == '/')
 -              len--;
 -
 -      if (!len)
 -              return -1;
 -
 -      if (submodule[len]) {
 -              /* We need to strip off one or more trailing slashes */
 -              char *stripped = xmemdupz(submodule, len);
 -
 -              refs = get_submodule_ref_store(stripped);
 -              free(stripped);
 -      } else {
 -              refs = get_submodule_ref_store(submodule);
 -      }
 +      refs = get_submodule_ref_store(submodule);
  
        if (!refs)
                return -1;
@@@ -1511,8 -1512,7 +1511,8 @@@ struct ref_store_hash_entr
        char name[FLEX_ARRAY];
  };
  
 -static int ref_store_hash_cmp(const void *entry, const void *entry_or_key,
 +static int ref_store_hash_cmp(const void *unused_cmp_data,
 +                            const void *entry, const void *entry_or_key,
                              const void *keydata)
  {
        const struct ref_store_hash_entry *e1 = entry, *e2 = entry_or_key;
@@@ -1595,7 -1595,7 +1595,7 @@@ static void register_ref_store_map(stru
                                   const char *name)
  {
        if (!map->tablesize)
 -              hashmap_init(map, ref_store_hash_cmp, 0);
 +              hashmap_init(map, ref_store_hash_cmp, NULL, 0);
  
        if (hashmap_put(map, alloc_ref_store_hash_entry(name, refs)))
                die("BUG: %s ref_store '%s' initialized twice", type, name);
@@@ -1605,32 -1605,31 +1605,32 @@@ struct ref_store *get_submodule_ref_sto
  {
        struct strbuf submodule_sb = STRBUF_INIT;
        struct ref_store *refs;
 -      int ret;
 +      char *to_free = NULL;
 +      size_t len;
  
 -      if (!submodule || !*submodule) {
 -              /*
 -               * FIXME: This case is ideally not allowed. But that
 -               * can't happen until we clean up all the callers.
 -               */
 -              return get_main_ref_store();
 -      }
 +      if (!submodule)
 +              return NULL;
 +
 +      len = strlen(submodule);
 +      while (len && is_dir_sep(submodule[len - 1]))
 +              len--;
 +      if (!len)
 +              return NULL;
 +
 +      if (submodule[len])
 +              /* We need to strip off one or more trailing slashes */
 +              submodule = to_free = xmemdupz(submodule, len);
  
        refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
        if (refs)
 -              return refs;
 +              goto done;
  
        strbuf_addstr(&submodule_sb, submodule);
 -      ret = is_nonbare_repository_dir(&submodule_sb);
 -      strbuf_release(&submodule_sb);
 -      if (!ret)
 -              return NULL;
 +      if (!is_nonbare_repository_dir(&submodule_sb))
 +              goto done;
  
 -      ret = submodule_to_gitdir(&submodule_sb, submodule);
 -      if (ret) {
 -              strbuf_release(&submodule_sb);
 -              return NULL;
 -      }
 +      if (submodule_to_gitdir(&submodule_sb, submodule))
 +              goto done;
  
        /* assume that add_submodule_odb() has been called */
        refs = ref_store_init(submodule_sb.buf,
        register_ref_store_map(&submodule_ref_stores, "submodule",
                               refs, submodule);
  
 +done:
        strbuf_release(&submodule_sb);
 +      free(to_free);
 +
        return refs;
  }
  
@@@ -2036,3 -2032,14 +2036,14 @@@ int rename_ref(const char *oldref, cons
  {
        return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
  }
+ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
+                   const char *newref, const char *logmsg)
+ {
+       return refs->be->copy_ref(refs, oldref, newref, logmsg);
+ }
+ int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
+ {
+       return refs_copy_existing_ref(get_main_ref_store(), oldref, newref, logmsg);
+ }
diff --combined refs.h
index e1c5803f9a5aba0b6ba18f5a9bd5192cba661542,00fce93f555746419ec4220240d0a66b86f8a7ab..a02b628c8fe81b648f13c66b7e618d8660151e77
--- 1/refs.h
--- 2/refs.h
+++ b/refs.h
@@@ -10,11 -10,10 +10,11 @@@ struct worktree
  /*
   * Resolve a reference, recursively following symbolic refererences.
   *
 - * Store the referred-to object's name in sha1 and return the name of
 - * the non-symbolic reference that ultimately pointed at it.  The
 - * return value, if not NULL, is a pointer into either a static buffer
 - * or the input ref.
 + * Return the name of the non-symbolic reference that ultimately pointed
 + * at the resolved object name.  The return value, if not NULL, is a
 + * pointer into either a static buffer or the input ref.
 + *
 + * If sha1 is non-NULL, store the referred-to object's name in it.
   *
   * If the reference cannot be resolved to an object, the behavior
   * depends on the RESOLVE_REF_READING flag:
@@@ -276,8 -275,6 +276,8 @@@ typedef int each_ref_fn(const char *ref
   * modifies the reference also returns a nonzero value to immediately
   * stop the iteration. Returned references are sorted.
   */
 +int refs_head_ref(struct ref_store *refs,
 +                each_ref_fn fn, void *cb_data);
  int refs_for_each_ref(struct ref_store *refs,
                      each_ref_fn fn, void *cb_data);
  int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
@@@ -292,9 -289,6 +292,9 @@@ int refs_for_each_remote_ref(struct ref
  int head_ref(each_ref_fn fn, void *cb_data);
  int for_each_ref(each_ref_fn fn, void *cb_data);
  int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data);
 +int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
 +                           each_ref_fn fn, void *cb_data,
 +                           unsigned int broken);
  int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data,
                        unsigned int broken);
  int for_each_tag_ref(each_ref_fn fn, void *cb_data);
@@@ -305,6 -299,18 +305,6 @@@ int for_each_glob_ref(each_ref_fn fn, c
  int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
                         const char *prefix, void *cb_data);
  
 -int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 -int for_each_ref_submodule(const char *submodule,
 -                         each_ref_fn fn, void *cb_data);
 -int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 -              each_ref_fn fn, void *cb_data);
 -int for_each_tag_ref_submodule(const char *submodule,
 -                             each_ref_fn fn, void *cb_data);
 -int for_each_branch_ref_submodule(const char *submodule,
 -                                each_ref_fn fn, void *cb_data);
 -int for_each_remote_ref_submodule(const char *submodule,
 -                                each_ref_fn fn, void *cb_data);
 -
  int head_ref_namespaced(each_ref_fn fn, void *cb_data);
  int for_each_namespaced_ref(each_ref_fn fn, void *cb_data);
  
@@@ -345,14 -351,6 +345,14 @@@ int refs_pack_refs(struct ref_store *re
  #define REF_NODEREF   0x01
  #define REF_FORCE_CREATE_REFLOG 0x40
  
 +/*
 + * Flags that can be passed in to ref_transaction_update
 + */
 +#define REF_TRANSACTION_UPDATE_ALLOWED_FLAGS \
 +      REF_ISPRUNING |                      \
 +      REF_FORCE_CREATE_REFLOG |            \
 +      REF_NODEREF
 +
  /*
   * Setup reflog before using. Fill in err and return -1 on failure.
   */
@@@ -442,7 -440,14 +442,14 @@@ char *shorten_unambiguous_ref(const cha
  /** rename ref, return 0 on success **/
  int refs_rename_ref(struct ref_store *refs, const char *oldref,
                    const char *newref, const char *logmsg);
- int rename_ref(const char *oldref, const char *newref, const char *logmsg);
+ int rename_ref(const char *oldref, const char *newref,
+                       const char *logmsg);
+ /** copy ref, return 0 on success **/
+ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
+                   const char *newref, const char *logmsg);
+ int copy_existing_ref(const char *oldref, const char *newref,
+                       const char *logmsg);
  
  int refs_create_symref(struct ref_store *refs, const char *refname,
                       const char *target, const char *logmsg);
@@@ -573,7 -578,7 +580,7 @@@ int ref_transaction_verify(struct ref_t
  #define TRANSACTION_GENERIC_ERROR -2
  
  /*
 - * Perform the preparatory stages of commiting `transaction`. Acquire
 + * Perform the preparatory stages of committing `transaction`. Acquire
   * any needed locks, check preconditions, etc.; basically, do as much
   * as possible to ensure that the transaction will be able to go
   * through, stopping just short of making any irrevocable or
   * On failure, abort the transaction, write an error message to `err`,
   * and return one of the `TRANSACTION_*` constants.
   *
 - * Callers who don't need such fine-grained control over commiting
 + * Callers who don't need such fine-grained control over committing
   * reference transactions should just call `ref_transaction_commit()`.
   */
  int ref_transaction_prepare(struct ref_transaction *transaction,
diff --combined refs/files-backend.c
index fec77744b40179b1454093bd37cf0815f3b755ae,fcaf4f719136e44ed9ce3a619157afe378ebd278..38d16a13a88ac99c5c8d1aeffbe85a74ab3ef345
@@@ -1,9 -1,7 +1,9 @@@
  #include "../cache.h"
 +#include "../config.h"
  #include "../refs.h"
  #include "refs-internal.h"
  #include "ref-cache.h"
 +#include "packed-backend.h"
  #include "../iterator.h"
  #include "../dir-iterator.h"
  #include "../lockfile.h"
  
  struct ref_lock {
        char *ref_name;
 -      struct lock_file *lk;
 +      struct lock_file lk;
        struct object_id old_oid;
  };
  
 -/*
 - * Return true if refname, which has the specified oid and flags, can
 - * be resolved to an object in the database. If the referred-to object
 - * does not exist, emit a warning and return false.
 - */
 -static int ref_resolves_to_object(const char *refname,
 -                                const struct object_id *oid,
 -                                unsigned int flags)
 -{
 -      if (flags & REF_ISBROKEN)
 -              return 0;
 -      if (!has_sha1_file(oid->hash)) {
 -              error("%s does not point to a valid object!", refname);
 -              return 0;
 -      }
 -      return 1;
 -}
 -
 -struct packed_ref_cache {
 -      struct ref_cache *cache;
 -
 -      /*
 -       * Count of references to the data structure in this instance,
 -       * including the pointer from files_ref_store::packed if any.
 -       * The data will not be freed as long as the reference count
 -       * is nonzero.
 -       */
 -      unsigned int referrers;
 -
 -      /* The metadata from when this packed-refs cache was read */
 -      struct stat_validity validity;
 -};
 -
  /*
   * Future: need to be in "struct repository"
   * when doing a full libification.
@@@ -26,12 -57,54 +26,12 @@@ struct files_ref_store 
  
        char *gitdir;
        char *gitcommondir;
 -      char *packed_refs_path;
  
        struct ref_cache *loose;
 -      struct packed_ref_cache *packed;
  
 -      /*
 -       * Lock used for the "packed-refs" file. Note that this (and
 -       * thus the enclosing `files_ref_store`) must not be freed.
 -       */
 -      struct lock_file packed_refs_lock;
 +      struct ref_store *packed_ref_store;
  };
  
 -/*
 - * Increment the reference count of *packed_refs.
 - */
 -static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
 -{
 -      packed_refs->referrers++;
 -}
 -
 -/*
 - * Decrease the reference count of *packed_refs.  If it goes to zero,
 - * free *packed_refs and return true; otherwise return false.
 - */
 -static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 -{
 -      if (!--packed_refs->referrers) {
 -              free_ref_cache(packed_refs->cache);
 -              stat_validity_clear(&packed_refs->validity);
 -              free(packed_refs);
 -              return 1;
 -      } else {
 -              return 0;
 -      }
 -}
 -
 -static void clear_packed_ref_cache(struct files_ref_store *refs)
 -{
 -      if (refs->packed) {
 -              struct packed_ref_cache *packed_refs = refs->packed;
 -
 -              if (is_lock_file_locked(&refs->packed_refs_lock))
 -                      die("BUG: packed-ref cache cleared while locked");
 -              refs->packed = NULL;
 -              release_packed_ref_cache(packed_refs);
 -      }
 -}
 -
  static void clear_loose_ref_cache(struct files_ref_store *refs)
  {
        if (refs->loose) {
@@@ -58,8 -131,7 +58,8 @@@ static struct ref_store *files_ref_stor
        get_common_dir_noenv(&sb, gitdir);
        refs->gitcommondir = strbuf_detach(&sb, NULL);
        strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
 -      refs->packed_refs_path = strbuf_detach(&sb, NULL);
 +      refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
 +      strbuf_release(&sb);
  
        return ref_store;
  }
@@@ -102,10 -174,169 +102,10 @@@ static struct files_ref_store *files_do
        return refs;
  }
  
 -/* The length of a peeled reference line in packed-refs, including EOL: */
 -#define PEELED_LINE_LENGTH 42
 -
 -/*
 - * The packed-refs header line that we write out.  Perhaps other
 - * traits will be added later.  The trailing space is required.
 - */
 -static const char PACKED_REFS_HEADER[] =
 -      "# pack-refs with: peeled fully-peeled \n";
 -
 -/*
 - * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 - * Return a pointer to the refname within the line (null-terminated),
 - * or NULL if there was a problem.
 - */
 -static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
 -{
 -      const char *ref;
 -
 -      if (parse_oid_hex(line->buf, oid, &ref) < 0)
 -              return NULL;
 -      if (!isspace(*ref++))
 -              return NULL;
 -
 -      if (isspace(*ref))
 -              return NULL;
 -
 -      if (line->buf[line->len - 1] != '\n')
 -              return NULL;
 -      line->buf[--line->len] = 0;
 -
 -      return ref;
 -}
 -
 -/*
 - * Read from `packed_refs_file` into a newly-allocated
 - * `packed_ref_cache` and return it. The return value will already
 - * have its reference count incremented.
 - *
 - * A comment line of the form "# pack-refs with: " may contain zero or
 - * more traits. We interpret the traits as follows:
 - *
 - *   No traits:
 - *
 - *      Probably no references are peeled. But if the file contains a
 - *      peeled value for a reference, we will use it.
 - *
 - *   peeled:
 - *
 - *      References under "refs/tags/", if they *can* be peeled, *are*
 - *      peeled in this file. References outside of "refs/tags/" are
 - *      probably not peeled even if they could have been, but if we find
 - *      a peeled value for such a reference we will use it.
 - *
 - *   fully-peeled:
 - *
 - *      All references in the file that can be peeled are peeled.
 - *      Inversely (and this is more important), any references in the
 - *      file for which no peeled value is recorded is not peelable. This
 - *      trait should typically be written alongside "peeled" for
 - *      compatibility with older clients, but we do not require it
 - *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
 - */
 -static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file)
 -{
 -      FILE *f;
 -      struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
 -      struct ref_entry *last = NULL;
 -      struct strbuf line = STRBUF_INIT;
 -      enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
 -      struct ref_dir *dir;
 -
 -      acquire_packed_ref_cache(packed_refs);
 -      packed_refs->cache = create_ref_cache(NULL, NULL);
 -      packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
 -
 -      f = fopen(packed_refs_file, "r");
 -      if (!f) {
 -              if (errno == ENOENT) {
 -                      /*
 -                       * This is OK; it just means that no
 -                       * "packed-refs" file has been written yet,
 -                       * which is equivalent to it being empty.
 -                       */
 -                      return packed_refs;
 -              } else {
 -                      die_errno("couldn't read %s", packed_refs_file);
 -              }
 -      }
 -
 -      stat_validity_update(&packed_refs->validity, fileno(f));
 -
 -      dir = get_ref_dir(packed_refs->cache->root);
 -      while (strbuf_getwholeline(&line, f, '\n') != EOF) {
 -              struct object_id oid;
 -              const char *refname;
 -              const char *traits;
 -
 -              if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
 -                      if (strstr(traits, " fully-peeled "))
 -                              peeled = PEELED_FULLY;
 -                      else if (strstr(traits, " peeled "))
 -                              peeled = PEELED_TAGS;
 -                      /* perhaps other traits later as well */
 -                      continue;
 -              }
 -
 -              refname = parse_ref_line(&line, &oid);
 -              if (refname) {
 -                      int flag = REF_ISPACKED;
 -
 -                      if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 -                              if (!refname_is_safe(refname))
 -                                      die("packed refname is dangerous: %s", refname);
 -                              oidclr(&oid);
 -                              flag |= REF_BAD_NAME | REF_ISBROKEN;
 -                      }
 -                      last = create_ref_entry(refname, &oid, flag);
 -                      if (peeled == PEELED_FULLY ||
 -                          (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
 -                              last->flag |= REF_KNOWS_PEELED;
 -                      add_ref_entry(dir, last);
 -                      continue;
 -              }
 -              if (last &&
 -                  line.buf[0] == '^' &&
 -                  line.len == PEELED_LINE_LENGTH &&
 -                  line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
 -                  !get_oid_hex(line.buf + 1, &oid)) {
 -                      oidcpy(&last->u.value.peeled, &oid);
 -                      /*
 -                       * Regardless of what the file header said,
 -                       * we definitely know the value of *this*
 -                       * reference:
 -                       */
 -                      last->flag |= REF_KNOWS_PEELED;
 -              }
 -      }
 -
 -      fclose(f);
 -      strbuf_release(&line);
 -
 -      return packed_refs;
 -}
 -
 -static const char *files_packed_refs_path(struct files_ref_store *refs)
 -{
 -      return refs->packed_refs_path;
 -}
 -
  static void files_reflog_path(struct files_ref_store *refs,
                              struct strbuf *sb,
                              const char *refname)
  {
 -      if (!refname) {
 -              /*
 -               * FIXME: of course this is wrong in multi worktree
 -               * setting. To be fixed real soon.
 -               */
 -              strbuf_addf(sb, "%s/logs", refs->gitcommondir);
 -              return;
 -      }
 -
        switch (ref_type(refname)) {
        case REF_TYPE_PER_WORKTREE:
        case REF_TYPE_PSEUDOREF:
@@@ -138,6 -369,60 +138,6 @@@ static void files_ref_path(struct files
        }
  }
  
 -/*
 - * Get the packed_ref_cache for the specified files_ref_store,
 - * creating and populating it if it hasn't been read before or if the
 - * file has been changed (according to its `validity` field) since it
 - * was last read. On the other hand, if we hold the lock, then assume
 - * that the file hasn't been changed out from under us, so skip the
 - * extra `stat()` call in `stat_validity_check()`.
 - */
 -static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *refs)
 -{
 -      const char *packed_refs_file = files_packed_refs_path(refs);
 -
 -      if (refs->packed &&
 -          !is_lock_file_locked(&refs->packed_refs_lock) &&
 -          !stat_validity_check(&refs->packed->validity, packed_refs_file))
 -              clear_packed_ref_cache(refs);
 -
 -      if (!refs->packed)
 -              refs->packed = read_packed_refs(packed_refs_file);
 -
 -      return refs->packed;
 -}
 -
 -static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
 -{
 -      return get_ref_dir(packed_ref_cache->cache->root);
 -}
 -
 -static struct ref_dir *get_packed_refs(struct files_ref_store *refs)
 -{
 -      return get_packed_ref_dir(get_packed_ref_cache(refs));
 -}
 -
 -/*
 - * Add a reference to the in-memory packed reference cache.  This may
 - * only be called while the packed-refs file is locked (see
 - * lock_packed_refs()).  To actually write the packed-refs file, call
 - * commit_packed_refs().
 - */
 -static void add_packed_ref(struct files_ref_store *refs,
 -                         const char *refname, const struct object_id *oid)
 -{
 -      struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
 -
 -      if (!is_lock_file_locked(&refs->packed_refs_lock))
 -              die("BUG: packed refs not locked");
 -
 -      if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
 -              die("Reference has invalid format: '%s'", refname);
 -
 -      add_ref_entry(get_packed_ref_dir(packed_ref_cache),
 -                    create_ref_entry(refname, oid, REF_ISPACKED));
 -}
 -
  /*
   * Read the loose references from the namespace dirname into dir
   * (without recursing).  dirname must end with '/'.  dir must be the
@@@ -260,6 -545,39 +260,6 @@@ static struct ref_cache *get_loose_ref_
        return refs->loose;
  }
  
 -/*
 - * Return the ref_entry for the given refname from the packed
 - * references.  If it does not exist, return NULL.
 - */
 -static struct ref_entry *get_packed_ref(struct files_ref_store *refs,
 -                                      const char *refname)
 -{
 -      return find_ref_entry(get_packed_refs(refs), refname);
 -}
 -
 -/*
 - * A loose ref file doesn't exist; check for a packed ref.
 - */
 -static int resolve_packed_ref(struct files_ref_store *refs,
 -                            const char *refname,
 -                            unsigned char *sha1, unsigned int *flags)
 -{
 -      struct ref_entry *entry;
 -
 -      /*
 -       * The loose reference file does not exist; check for a packed
 -       * reference.
 -       */
 -      entry = get_packed_ref(refs, refname);
 -      if (entry) {
 -              hashcpy(sha1, entry->u.value.oid.hash);
 -              *flags |= REF_ISPACKED;
 -              return 0;
 -      }
 -      /* refname is not a packed reference. */
 -      return -1;
 -}
 -
  static int files_read_raw_ref(struct ref_store *ref_store,
                              const char *refname, unsigned char *sha1,
                              struct strbuf *referent, unsigned int *type)
@@@ -303,8 -621,7 +303,8 @@@ stat_ref
        if (lstat(path, &st) < 0) {
                if (errno != ENOENT)
                        goto out;
 -              if (resolve_packed_ref(refs, refname, sha1, type)) {
 +              if (refs_read_raw_ref(refs->packed_ref_store, refname,
 +                                    sha1, referent, type)) {
                        errno = ENOENT;
                        goto out;
                }
                 * ref is supposed to be, there could still be a
                 * packed ref:
                 */
 -              if (resolve_packed_ref(refs, refname, sha1, type)) {
 +              if (refs_read_raw_ref(refs->packed_ref_store, refname,
 +                                    sha1, referent, type)) {
                        errno = EISDIR;
                        goto out;
                }
@@@ -409,7 -725,9 +409,7 @@@ out
  
  static void unlock_ref(struct ref_lock *lock)
  {
 -      /* Do not free lock->lk -- atexit() still looks at them */
 -      if (lock->lk)
 -              rollback_lock_file(lock->lk);
 +      rollback_lock_file(&lock->lk);
        free(lock->ref_name);
        free(lock);
  }
@@@ -523,9 -841,10 +523,9 @@@ retry
                goto error_return;
        }
  
 -      if (!lock->lk)
 -              lock->lk = xcalloc(1, sizeof(struct lock_file));
 -
 -      if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
 +      if (hold_lock_file_for_update_timeout(
 +                          &lock->lk, ref_file.buf, LOCK_NO_DEREF,
 +                          get_files_ref_lock_timeout_ms()) < 0) {
                if (errno == ENOENT && --attempts_remaining > 0) {
                        /*
                         * Maybe somebody just deleted one of the
  
                /*
                 * If the ref did not exist and we are creating it,
 -               * make sure there is no existing ref that conflicts
 -               * with refname:
 +               * make sure there is no existing packed ref that
 +               * conflicts with refname:
                 */
                if (refs_verify_refname_available(
 -                                  &refs->base, refname,
 +                                  refs->packed_ref_store, refname,
                                    extras, skip, err))
                        goto error_return;
        }
@@@ -671,9 -990,15 +671,9 @@@ static int files_peel_ref(struct ref_st
         * be expensive and (b) loose references anyway usually do not
         * have REF_KNOWS_PEELED.
         */
 -      if (flag & REF_ISPACKED) {
 -              struct ref_entry *r = get_packed_ref(refs, refname);
 -              if (r) {
 -                      if (peel_entry(r, 0))
 -                              return -1;
 -                      hashcpy(sha1, r->u.value.peeled.hash);
 -                      return 0;
 -              }
 -      }
 +      if (flag & REF_ISPACKED &&
 +          !refs_peel_ref(refs->packed_ref_store, refname, sha1))
 +              return 0;
  
        return peel_object(base, sha1);
  }
  struct files_ref_iterator {
        struct ref_iterator base;
  
 -      struct packed_ref_cache *packed_ref_cache;
        struct ref_iterator *iter0;
        unsigned int flags;
  };
@@@ -733,6 -1059,7 +733,6 @@@ static int files_ref_iterator_abort(str
        if (iter->iter0)
                ok = ref_iterator_abort(iter->iter0);
  
 -      release_packed_ref_cache(iter->packed_ref_cache);
        base_ref_iterator_free(ref_iterator);
        return ok;
  }
@@@ -774,28 -1101,18 +774,28 @@@ static struct ref_iterator *files_ref_i
         * (If they've already been read, that's OK; we only need to
         * guarantee that they're read before the packed refs, not
         * *how much* before.) After that, we call
 -       * get_packed_ref_cache(), which internally checks whether the
 -       * packed-ref cache is up to date with what is on disk, and
 -       * re-reads it if not.
 +       * packed_ref_iterator_begin(), which internally checks
 +       * whether the packed-ref cache is up to date with what is on
 +       * disk, and re-reads it if not.
         */
  
        loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
                                              prefix, 1);
  
 -      iter->packed_ref_cache = get_packed_ref_cache(refs);
 -      acquire_packed_ref_cache(iter->packed_ref_cache);
 -      packed_iter = cache_ref_iterator_begin(iter->packed_ref_cache->cache,
 -                                             prefix, 0);
 +      /*
 +       * The packed-refs file might contain broken references, for
 +       * example an old version of a reference that points at an
 +       * object that has since been garbage-collected. This is OK as
 +       * long as there is a corresponding loose reference that
 +       * overrides it, and we don't want to emit an error message in
 +       * this case. So ask the packed_ref_store for all of its
 +       * references, and (if needed) do our own check for broken
 +       * ones in files_ref_iterator_advance(), after we have merged
 +       * the packed and loose references.
 +       */
 +      packed_iter = refs_ref_iterator_begin(
 +                      refs->packed_ref_store, prefix, 0,
 +                      DO_FOR_EACH_INCLUDE_BROKEN);
  
        iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
        iter->flags = flags;
@@@ -853,9 -1170,7 +853,9 @@@ static int create_reflock(const char *p
  {
        struct lock_file *lk = cb;
  
 -      return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0;
 +      return hold_lock_file_for_update_timeout(
 +                      lk, path, LOCK_NO_DEREF,
 +                      get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
  }
  
  /*
@@@ -929,15 -1244,17 +929,15 @@@ static struct ref_lock *lock_ref_sha1_b
         * our refname.
         */
        if (is_null_oid(&lock->old_oid) &&
 -          refs_verify_refname_available(&refs->base, refname,
 +          refs_verify_refname_available(refs->packed_ref_store, refname,
                                          extras, skip, err)) {
                last_errno = ENOTDIR;
                goto error_return;
        }
  
 -      lock->lk = xcalloc(1, sizeof(struct lock_file));
 -
        lock->ref_name = xstrdup(refname);
  
 -      if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
 +      if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
                last_errno = errno;
                unable_to_lock_message(ref_file.buf, errno, err);
                goto error_return;
        return lock;
  }
  
 -/*
 - * Write an entry to the packed-refs file for the specified refname.
 - * If peeled is non-NULL, write it as the entry's peeled value.
 - */
 -static void write_packed_entry(FILE *fh, const char *refname,
 -                             const unsigned char *sha1,
 -                             const unsigned char *peeled)
 -{
 -      fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
 -      if (peeled)
 -              fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
 -}
 -
 -/*
 - * Lock the packed-refs file for writing. Flags is passed to
 - * hold_lock_file_for_update(). Return 0 on success. On errors, set
 - * errno appropriately and return a nonzero value.
 - */
 -static int lock_packed_refs(struct files_ref_store *refs, int flags)
 -{
 -      static int timeout_configured = 0;
 -      static int timeout_value = 1000;
 -      struct packed_ref_cache *packed_ref_cache;
 -
 -      files_assert_main_repository(refs, "lock_packed_refs");
 -
 -      if (!timeout_configured) {
 -              git_config_get_int("core.packedrefstimeout", &timeout_value);
 -              timeout_configured = 1;
 -      }
 -
 -      if (hold_lock_file_for_update_timeout(
 -                          &refs->packed_refs_lock, files_packed_refs_path(refs),
 -                          flags, timeout_value) < 0)
 -              return -1;
 -      /*
 -       * Get the current packed-refs while holding the lock. It is
 -       * important that we call `get_packed_ref_cache()` before
 -       * setting `packed_ref_cache->lock`, because otherwise the
 -       * former will see that the file is locked and assume that the
 -       * cache can't be stale.
 -       */
 -      packed_ref_cache = get_packed_ref_cache(refs);
 -      /* Increment the reference count to prevent it from being freed: */
 -      acquire_packed_ref_cache(packed_ref_cache);
 -      return 0;
 -}
 -
 -/*
 - * Write the current version of the packed refs cache from memory to
 - * disk. The packed-refs file must already be locked for writing (see
 - * lock_packed_refs()). Return zero on success. On errors, set errno
 - * and return a nonzero value
 - */
 -static int commit_packed_refs(struct files_ref_store *refs)
 -{
 -      struct packed_ref_cache *packed_ref_cache =
 -              get_packed_ref_cache(refs);
 -      int ok, error = 0;
 -      int save_errno = 0;
 -      FILE *out;
 -      struct ref_iterator *iter;
 -
 -      files_assert_main_repository(refs, "commit_packed_refs");
 -
 -      if (!is_lock_file_locked(&refs->packed_refs_lock))
 -              die("BUG: packed-refs not locked");
 -
 -      out = fdopen_lock_file(&refs->packed_refs_lock, "w");
 -      if (!out)
 -              die_errno("unable to fdopen packed-refs descriptor");
 -
 -      fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
 -
 -      iter = cache_ref_iterator_begin(packed_ref_cache->cache, NULL, 0);
 -      while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
 -              struct object_id peeled;
 -              int peel_error = ref_iterator_peel(iter, &peeled);
 -
 -              write_packed_entry(out, iter->refname, iter->oid->hash,
 -                                 peel_error ? NULL : peeled.hash);
 -      }
 -
 -      if (ok != ITER_DONE)
 -              die("error while iterating over references");
 -
 -      if (commit_lock_file(&refs->packed_refs_lock)) {
 -              save_errno = errno;
 -              error = -1;
 -      }
 -      release_packed_ref_cache(packed_ref_cache);
 -      errno = save_errno;
 -      return error;
 -}
 -
 -/*
 - * Rollback the lockfile for the packed-refs file, and discard the
 - * in-memory packed reference cache.  (The packed-refs file will be
 - * read anew if it is needed again after this function is called.)
 - */
 -static void rollback_packed_refs(struct files_ref_store *refs)
 -{
 -      struct packed_ref_cache *packed_ref_cache =
 -              get_packed_ref_cache(refs);
 -
 -      files_assert_main_repository(refs, "rollback_packed_refs");
 -
 -      if (!is_lock_file_locked(&refs->packed_refs_lock))
 -              die("BUG: packed-refs not locked");
 -      rollback_lock_file(&refs->packed_refs_lock);
 -      release_packed_ref_cache(packed_ref_cache);
 -      clear_packed_ref_cache(refs);
 -}
 -
  struct ref_to_prune {
        struct ref_to_prune *next;
        unsigned char sha1[20];
@@@ -1041,17 -1472,11 +1041,17 @@@ static void prune_ref(struct files_ref_
        strbuf_release(&err);
  }
  
 -static void prune_refs(struct files_ref_store *refs, struct ref_to_prune *r)
 +/*
 + * Prune the loose versions of the references in the linked list
 + * `*refs_to_prune`, freeing the entries in the list as we go.
 + */
 +static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
  {
 -      while (r) {
 +      while (*refs_to_prune) {
 +              struct ref_to_prune *r = *refs_to_prune;
 +              *refs_to_prune = r->next;
                prune_ref(refs, r);
 -              r = r->next;
 +              free(r);
        }
  }
  
@@@ -1087,16 -1512,12 +1087,16 @@@ static int files_pack_refs(struct ref_s
                files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
                               "pack_refs");
        struct ref_iterator *iter;
 -      struct ref_dir *packed_refs;
        int ok;
        struct ref_to_prune *refs_to_prune = NULL;
 +      struct strbuf err = STRBUF_INIT;
 +      struct ref_transaction *transaction;
 +
 +      transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
 +      if (!transaction)
 +              return -1;
  
 -      lock_packed_refs(refs, LOCK_DIE_ON_ERROR);
 -      packed_refs = get_packed_refs(refs);
 +      packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
  
        iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
        while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
                 * in the packed ref cache. If the reference should be
                 * pruned, also add it to refs_to_prune.
                 */
 -              struct ref_entry *packed_entry;
 -
                if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
                                     flags))
                        continue;
  
                /*
 -               * Create an entry in the packed-refs cache equivalent
 -               * to the one from the loose ref cache, except that
 -               * we don't copy the peeled status, because we want it
 -               * to be re-peeled.
 +               * Add a reference creation for this reference to the
 +               * packed-refs transaction:
                 */
 -              packed_entry = find_ref_entry(packed_refs, iter->refname);
 -              if (packed_entry) {
 -                      /* Overwrite existing packed entry with info from loose entry */
 -                      packed_entry->flag = REF_ISPACKED;
 -                      oidcpy(&packed_entry->u.value.oid, iter->oid);
 -              } else {
 -                      packed_entry = create_ref_entry(iter->refname, iter->oid,
 -                                                      REF_ISPACKED);
 -                      add_ref_entry(packed_refs, packed_entry);
 -              }
 -              oidclr(&packed_entry->u.value.peeled);
 +              if (ref_transaction_update(transaction, iter->refname,
 +                                         iter->oid->hash, NULL,
 +                                         REF_NODEREF, NULL, &err))
 +                      die("failure preparing to create packed reference %s: %s",
 +                          iter->refname, err.buf);
  
                /* Schedule the loose reference for pruning if requested. */
                if ((flags & PACK_REFS_PRUNE)) {
        if (ok != ITER_DONE)
                die("error while iterating over references");
  
 -      if (commit_packed_refs(refs))
 -              die_errno("unable to overwrite old ref-pack file");
 -
 -      prune_refs(refs, refs_to_prune);
 -      return 0;
 -}
 -
 -/*
 - * Rewrite the packed-refs file, omitting any refs listed in
 - * 'refnames'. On error, leave packed-refs unchanged, write an error
 - * message to 'err', and return a nonzero value.
 - *
 - * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
 - */
 -static int repack_without_refs(struct files_ref_store *refs,
 -                             struct string_list *refnames, struct strbuf *err)
 -{
 -      struct ref_dir *packed;
 -      struct string_list_item *refname;
 -      int ret, needs_repacking = 0, removed = 0;
 -
 -      files_assert_main_repository(refs, "repack_without_refs");
 -      assert(err);
 -
 -      /* Look for a packed ref */
 -      for_each_string_list_item(refname, refnames) {
 -              if (get_packed_ref(refs, refname->string)) {
 -                      needs_repacking = 1;
 -                      break;
 -              }
 -      }
 -
 -      /* Avoid locking if we have nothing to do */
 -      if (!needs_repacking)
 -              return 0; /* no refname exists in packed refs */
 +      if (ref_transaction_commit(transaction, &err))
 +              die("unable to write new packed-refs: %s", err.buf);
  
 -      if (lock_packed_refs(refs, 0)) {
 -              unable_to_lock_message(files_packed_refs_path(refs), errno, err);
 -              return -1;
 -      }
 -      packed = get_packed_refs(refs);
 +      ref_transaction_free(transaction);
  
 -      /* Remove refnames from the cache */
 -      for_each_string_list_item(refname, refnames)
 -              if (remove_entry_from_dir(packed, refname->string) != -1)
 -                      removed = 1;
 -      if (!removed) {
 -              /*
 -               * All packed entries disappeared while we were
 -               * acquiring the lock.
 -               */
 -              rollback_packed_refs(refs);
 -              return 0;
 -      }
 +      packed_refs_unlock(refs->packed_ref_store);
  
 -      /* Write what remains */
 -      ret = commit_packed_refs(refs);
 -      if (ret)
 -              strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
 -                          strerror(errno));
 -      return ret;
 +      prune_refs(refs, &refs_to_prune);
 +      strbuf_release(&err);
 +      return 0;
  }
  
  static int files_delete_refs(struct ref_store *ref_store, const char *msg,
        if (!refnames->nr)
                return 0;
  
 -      result = repack_without_refs(refs, refnames, &err);
 -      if (result) {
 -              /*
 -               * If we failed to rewrite the packed-refs file, then
 -               * it is unsafe to try to remove loose refs, because
 -               * doing so might expose an obsolete packed value for
 -               * a reference that might even point at an object that
 -               * has been garbage collected.
 -               */
 -              if (refnames->nr == 1)
 -                      error(_("could not delete reference %s: %s"),
 -                            refnames->items[0].string, err.buf);
 -              else
 -                      error(_("could not delete references: %s"), err.buf);
 +      if (packed_refs_lock(refs->packed_ref_store, 0, &err))
 +              goto error;
  
 -              goto out;
 +      if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
 +              packed_refs_unlock(refs->packed_ref_store);
 +              goto error;
        }
  
 +      packed_refs_unlock(refs->packed_ref_store);
 +
        for (i = 0; i < refnames->nr; i++) {
                const char *refname = refnames->items[i].string;
  
                        result |= error(_("could not remove reference %s"), refname);
        }
  
 -out:
        strbuf_release(&err);
        return result;
 +
 +error:
 +      /*
 +       * If we failed to rewrite the packed-refs file, then it is
 +       * unsafe to try to remove loose refs, because doing so might
 +       * expose an obsolete packed value for a reference that might
 +       * even point at an object that has been garbage collected.
 +       */
 +      if (refnames->nr == 1)
 +              error(_("could not delete reference %s: %s"),
 +                    refnames->items[0].string, err.buf);
 +      else
 +              error(_("could not delete references: %s"), err.buf);
 +
 +      strbuf_release(&err);
 +      return -1;
  }
  
  /*
@@@ -1258,9 -1733,9 +1258,9 @@@ static int commit_ref_update(struct fil
                             const struct object_id *oid, const char *logmsg,
                             struct strbuf *err);
  
- static int files_rename_ref(struct ref_store *ref_store,
+ static int files_copy_or_rename_ref(struct ref_store *ref_store,
                            const char *oldrefname, const char *newrefname,
-                           const char *logmsg)
+                           const char *logmsg, int copy)
  {
        struct files_ref_store *refs =
                files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
        }
  
        if (flag & REF_ISSYMREF) {
-               ret = error("refname %s is a symbolic ref, renaming it is not supported",
-                           oldrefname);
+               if (copy)
+                       ret = error("refname %s is a symbolic ref, copying it is not supported",
+                                   oldrefname);
+               else
+                       ret = error("refname %s is a symbolic ref, renaming it is not supported",
+                                   oldrefname);
                goto out;
        }
        if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
                goto out;
        }
  
-       if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
+       if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
                ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
                            oldrefname, strerror(errno));
                goto out;
        }
  
-       if (refs_delete_ref(&refs->base, logmsg, oldrefname,
+       if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
+               ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
+                           oldrefname, strerror(errno));
+               goto out;
+       }
+       if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
                            orig_oid.hash, REF_NODEREF)) {
                error("unable to delete old %s", oldrefname);
                goto rollback;
         * the safety anyway; we want to delete the reference whatever
         * its current value.
         */
-       if (!refs_read_ref_full(&refs->base, newrefname,
+       if (!copy && !refs_read_ref_full(&refs->base, newrefname,
                                RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
                                oid.hash, NULL) &&
            refs_delete_ref(&refs->base, NULL, newrefname,
        lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
                                   REF_NODEREF, NULL, &err);
        if (!lock) {
-               error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+               if (copy)
+                       error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+               else
+                       error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
                strbuf_release(&err);
                goto rollback;
        }
        return ret;
  }
  
 -static int close_ref(struct ref_lock *lock)
+ static int files_rename_ref(struct ref_store *ref_store,
+                           const char *oldrefname, const char *newrefname,
+                           const char *logmsg)
+ {
+       return files_copy_or_rename_ref(ref_store, oldrefname,
+                                newrefname, logmsg, 0);
+ }
+ static int files_copy_ref(struct ref_store *ref_store,
+                           const char *oldrefname, const char *newrefname,
+                           const char *logmsg)
+ {
+       return files_copy_or_rename_ref(ref_store, oldrefname,
+                                newrefname, logmsg, 1);
+ }
 +static int close_ref_gently(struct ref_lock *lock)
  {
 -      if (close_lock_file(lock->lk))
 +      if (close_lock_file_gently(&lock->lk))
                return -1;
        return 0;
  }
  
  static int commit_ref(struct ref_lock *lock)
  {
 -      char *path = get_locked_file_path(lock->lk);
 +      char *path = get_locked_file_path(&lock->lk);
        struct stat st;
  
        if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
                free(path);
        }
  
 -      if (commit_lock_file(lock->lk))
 +      if (commit_lock_file(&lock->lk))
                return -1;
        return 0;
  }
@@@ -1549,7 -2053,7 +1578,7 @@@ static int log_ref_write_fd(int fd, con
  
        written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
        free(logrec);
 -      if (written != len)
 +      if (written < 0)
                return -1;
  
        return 0;
@@@ -1627,12 -2131,12 +1656,12 @@@ static int write_ref_to_lockfile(struc
                unlock_ref(lock);
                return -1;
        }
 -      fd = get_lock_file_fd(lock->lk);
 -      if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
 -          write_in_full(fd, &term, 1) != 1 ||
 -          close_ref(lock) < 0) {
 +      fd = get_lock_file_fd(&lock->lk);
 +      if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
 +          write_in_full(fd, &term, 1) < 0 ||
 +          close_ref_gently(lock) < 0) {
                strbuf_addf(err,
 -                          "couldn't write '%s'", get_lock_file_path(lock->lk));
 +                          "couldn't write '%s'", get_lock_file_path(&lock->lk));
                unlock_ref(lock);
                return -1;
        }
@@@ -1676,12 -2180,13 +1705,12 @@@ static int commit_ref_update(struct fil
                 * check with HEAD only which should cover 99% of all usage
                 * scenarios (even 100% of the default ones).
                 */
 -              struct object_id head_oid;
                int head_flag;
                const char *head_ref;
  
                head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
                                                   RESOLVE_REF_READING,
 -                                                 head_oid.hash, &head_flag);
 +                                                 NULL, &head_flag);
                if (head_ref && (head_flag & REF_ISSYMREF) &&
                    !strcmp(head_ref, lock->ref_name)) {
                        struct strbuf log_err = STRBUF_INIT;
@@@ -1708,7 -2213,7 +1737,7 @@@ static int create_ref_symlink(struct re
  {
        int ret = -1;
  #ifndef NO_SYMLINK_HEAD
 -      char *ref_path = get_locked_file_path(lock->lk);
 +      char *ref_path = get_locked_file_path(&lock->lk);
        unlink(ref_path);
        ret = symlink(target, ref_path);
        free(ref_path);
@@@ -1744,14 -2249,14 +1773,14 @@@ static int create_symref_locked(struct 
                return 0;
        }
  
 -      if (!fdopen_lock_file(lock->lk, "w"))
 +      if (!fdopen_lock_file(&lock->lk, "w"))
                return error("unable to fdopen %s: %s",
 -                           lock->lk->tempfile.filename.buf, strerror(errno));
 +                           lock->lk.tempfile->filename.buf, strerror(errno));
  
        update_symref_reflog(refs, lock, refname, target, logmsg);
  
        /* no error check; commit_ref will check ferror */
 -      fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
 +      fprintf(lock->lk.tempfile->fp, "ref: %s\n", target);
        if (commit_ref(lock) < 0)
                return error("unable to write symref for %s: %s", refname,
                             strerror(errno));
@@@ -2058,63 -2563,23 +2087,63 @@@ static struct ref_iterator_vtable files
        files_reflog_iterator_abort
  };
  
 -static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
 +static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
 +                                                const char *gitdir)
  {
 -      struct files_ref_store *refs =
 -              files_downcast(ref_store, REF_STORE_READ,
 -                             "reflog_iterator_begin");
        struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
        struct ref_iterator *ref_iterator = &iter->base;
        struct strbuf sb = STRBUF_INIT;
  
        base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
 -      files_reflog_path(refs, &sb, NULL);
 +      strbuf_addf(&sb, "%s/logs", gitdir);
        iter->dir_iterator = dir_iterator_begin(sb.buf);
        iter->ref_store = ref_store;
        strbuf_release(&sb);
 +
        return ref_iterator;
  }
  
 +static enum iterator_selection reflog_iterator_select(
 +      struct ref_iterator *iter_worktree,
 +      struct ref_iterator *iter_common,
 +      void *cb_data)
 +{
 +      if (iter_worktree) {
 +              /*
 +               * We're a bit loose here. We probably should ignore
 +               * common refs if they are accidentally added as
 +               * per-worktree refs.
 +               */
 +              return ITER_SELECT_0;
 +      } else if (iter_common) {
 +              if (ref_type(iter_common->refname) == REF_TYPE_NORMAL)
 +                      return ITER_SELECT_1;
 +
 +              /*
 +               * The main ref store may contain main worktree's
 +               * per-worktree refs, which should be ignored
 +               */
 +              return ITER_SKIP_1;
 +      } else
 +              return ITER_DONE;
 +}
 +
 +static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
 +{
 +      struct files_ref_store *refs =
 +              files_downcast(ref_store, REF_STORE_READ,
 +                             "reflog_iterator_begin");
 +
 +      if (!strcmp(refs->gitdir, refs->gitcommondir)) {
 +              return reflog_iterator_begin(ref_store, refs->gitcommondir);
 +      } else {
 +              return merge_ref_iterator_begin(
 +                      reflog_iterator_begin(ref_store, refs->gitdir),
 +                      reflog_iterator_begin(ref_store, refs->gitcommondir),
 +                      reflog_iterator_select, refs);
 +      }
 +}
 +
  /*
   * If update is a direct update of head_ref (the reference pointed to
   * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
@@@ -2138,10 -2603,11 +2167,10 @@@ static int split_head_update(struct ref
  
        /*
         * First make sure that HEAD is not already in the
 -       * transaction. This insertion is O(N) in the transaction
 +       * transaction. This check is O(lg N) in the transaction
         * size, but it happens at most once per transaction.
         */
 -      item = string_list_insert(affected_refnames, "HEAD");
 -      if (item->util) {
 +      if (string_list_has_string(affected_refnames, "HEAD")) {
                /* An entry already existed */
                strbuf_addf(err,
                            "multiple updates for 'HEAD' (including one "
                        update->new_oid.hash, update->old_oid.hash,
                        update->msg);
  
 +      /*
 +       * Add "HEAD". This insertion is O(N) in the transaction
 +       * size, but it happens at most once per transaction.
 +       * Add new_update->refname instead of a literal "HEAD".
 +       */
 +      if (strcmp(new_update->refname, "HEAD"))
 +              BUG("%s unexpectedly not 'HEAD'", new_update->refname);
 +      item = string_list_insert(affected_refnames, new_update->refname);
        item->util = new_update;
  
        return 0;
@@@ -2190,12 -2648,13 +2219,12 @@@ static int split_symref_update(struct f
  
        /*
         * First make sure that referent is not already in the
 -       * transaction. This insertion is O(N) in the transaction
 +       * transaction. This check is O(lg N) in the transaction
         * size, but it happens at most once per symref in a
         * transaction.
         */
 -      item = string_list_insert(affected_refnames, referent);
 -      if (item->util) {
 -              /* An entry already existed */
 +      if (string_list_has_string(affected_refnames, referent)) {
 +              /* An entry already exists */
                strbuf_addf(err,
                            "multiple updates for '%s' (including one "
                            "via symref '%s') are not allowed",
        update->flags |= REF_LOG_ONLY | REF_NODEREF;
        update->flags &= ~REF_HAVE_OLD;
  
 +      /*
 +       * Add the referent. This insertion is O(N) in the transaction
 +       * size, but it happens at most once per symref in a
 +       * transaction. Make sure to add new_update->refname, which will
 +       * be valid as long as affected_refnames is in use, and NOT
 +       * referent, which might soon be freed by our caller.
 +       */
 +      item = string_list_insert(affected_refnames, new_update->refname);
 +      if (item->util)
 +              BUG("%s unexpectedly found in affected_refnames",
 +                  new_update->refname);
        item->util = new_update;
  
        return 0;
@@@ -2312,7 -2760,7 +2341,7 @@@ static int lock_ref_for_update(struct f
        struct strbuf referent = STRBUF_INIT;
        int mustexist = (update->flags & REF_HAVE_OLD) &&
                !is_null_oid(&update->old_oid);
 -      int ret;
 +      int ret = 0;
        struct ref_lock *lock;
  
        files_assert_main_repository(refs, "lock_ref_for_update");
                ret = split_head_update(update, transaction, head_ref,
                                        affected_refnames, err);
                if (ret)
 -                      return ret;
 +                      goto out;
        }
  
        ret = lock_raw_ref(refs, update->refname, mustexist,
                strbuf_addf(err, "cannot lock ref '%s': %s",
                            original_update_refname(update), reason);
                free(reason);
 -              return ret;
 +              goto out;
        }
  
        update->backend_data = lock;
                                        strbuf_addf(err, "cannot lock ref '%s': "
                                                    "error reading reference",
                                                    original_update_refname(update));
 -                                      return -1;
 +                                      ret = TRANSACTION_GENERIC_ERROR;
 +                                      goto out;
                                }
                        } else if (check_old_oid(update, &lock->old_oid, err)) {
 -                              return TRANSACTION_GENERIC_ERROR;
 +                              ret = TRANSACTION_GENERIC_ERROR;
 +                              goto out;
                        }
                } else {
                        /*
                                                  referent.buf, transaction,
                                                  affected_refnames, err);
                        if (ret)
 -                              return ret;
 +                              goto out;
                }
        } else {
                struct ref_update *parent_update;
  
 -              if (check_old_oid(update, &lock->old_oid, err))
 -                      return TRANSACTION_GENERIC_ERROR;
 +              if (check_old_oid(update, &lock->old_oid, err)) {
 +                      ret = TRANSACTION_GENERIC_ERROR;
 +                      goto out;
 +              }
  
                /*
                 * If this update is happening indirectly because of a
                                    "cannot update ref '%s': %s",
                                    update->refname, write_err);
                        free(write_err);
 -                      return TRANSACTION_GENERIC_ERROR;
 +                      ret = TRANSACTION_GENERIC_ERROR;
 +                      goto out;
                } else {
                        update->flags |= REF_NEEDS_COMMIT;
                }
                 * the lockfile is still open. Close it to
                 * free up the file descriptor:
                 */
 -              if (close_ref(lock)) {
 +              if (close_ref_gently(lock)) {
                        strbuf_addf(err, "couldn't close '%s.lock'",
                                    update->refname);
 -                      return TRANSACTION_GENERIC_ERROR;
 +                      ret = TRANSACTION_GENERIC_ERROR;
 +                      goto out;
                }
        }
 -      return 0;
 +
 +out:
 +      strbuf_release(&referent);
 +      return ret;
  }
  
 +struct files_transaction_backend_data {
 +      struct ref_transaction *packed_transaction;
 +      int packed_refs_locked;
 +};
 +
  /*
   * Unlock any references in `transaction` that are still locked, and
   * mark the transaction closed.
   */
 -static void files_transaction_cleanup(struct ref_transaction *transaction)
 +static void files_transaction_cleanup(struct files_ref_store *refs,
 +                                    struct ref_transaction *transaction)
  {
        size_t i;
 +      struct files_transaction_backend_data *backend_data =
 +              transaction->backend_data;
 +      struct strbuf err = STRBUF_INIT;
  
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
                }
        }
  
 +      if (backend_data->packed_transaction &&
 +          ref_transaction_abort(backend_data->packed_transaction, &err)) {
 +              error("error aborting transaction: %s", err.buf);
 +              strbuf_release(&err);
 +      }
 +
 +      if (backend_data->packed_refs_locked)
 +              packed_refs_unlock(refs->packed_ref_store);
 +
 +      free(backend_data);
 +
        transaction->state = REF_TRANSACTION_CLOSED;
  }
  
@@@ -2500,17 -2919,12 +2529,17 @@@ static int files_transaction_prepare(st
        char *head_ref = NULL;
        int head_type;
        struct object_id head_oid;
 +      struct files_transaction_backend_data *backend_data;
 +      struct ref_transaction *packed_transaction = NULL;
  
        assert(err);
  
        if (!transaction->nr)
                goto cleanup;
  
 +      backend_data = xcalloc(1, sizeof(*backend_data));
 +      transaction->backend_data = backend_data;
 +
        /*
         * Fail if a refname appears more than once in the
         * transaction. (If we end up splitting up any updates using
                                       head_oid.hash, &head_type);
  
        if (head_ref && !(head_type & REF_ISSYMREF)) {
 -              free(head_ref);
 -              head_ref = NULL;
 +              FREE_AND_NULL(head_ref);
        }
  
        /*
                                          head_ref, &affected_refnames, err);
                if (ret)
                        break;
 +
 +              if (update->flags & REF_DELETING &&
 +                  !(update->flags & REF_LOG_ONLY) &&
 +                  !(update->flags & REF_ISPRUNING)) {
 +                      /*
 +                       * This reference has to be deleted from
 +                       * packed-refs if it exists there.
 +                       */
 +                      if (!packed_transaction) {
 +                              packed_transaction = ref_store_transaction_begin(
 +                                              refs->packed_ref_store, err);
 +                              if (!packed_transaction) {
 +                                      ret = TRANSACTION_GENERIC_ERROR;
 +                                      goto cleanup;
 +                              }
 +
 +                              backend_data->packed_transaction =
 +                                      packed_transaction;
 +                      }
 +
 +                      ref_transaction_add_update(
 +                                      packed_transaction, update->refname,
 +                                      update->flags & ~REF_HAVE_OLD,
 +                                      update->new_oid.hash, update->old_oid.hash,
 +                                      NULL);
 +              }
 +      }
 +
 +      if (packed_transaction) {
 +              if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
 +                      ret = TRANSACTION_GENERIC_ERROR;
 +                      goto cleanup;
 +              }
 +              backend_data->packed_refs_locked = 1;
 +              ret = ref_transaction_prepare(packed_transaction, err);
        }
  
  cleanup:
        string_list_clear(&affected_refnames, 0);
  
        if (ret)
 -              files_transaction_cleanup(transaction);
 +              files_transaction_cleanup(refs, transaction);
        else
                transaction->state = REF_TRANSACTION_PREPARED;
  
@@@ -2634,10 -3014,9 +2663,10 @@@ static int files_transaction_finish(str
                files_downcast(ref_store, 0, "ref_transaction_finish");
        size_t i;
        int ret = 0;
 -      struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
 -      struct string_list_item *ref_to_delete;
        struct strbuf sb = STRBUF_INIT;
 +      struct files_transaction_backend_data *backend_data;
 +      struct ref_transaction *packed_transaction;
 +
  
        assert(err);
  
                return 0;
        }
  
 +      backend_data = transaction->backend_data;
 +      packed_transaction = backend_data->packed_transaction;
 +
        /* Perform updates first so live commits remain referenced */
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
                        }
                }
        }
 -      /* Perform deletes now that updates are safely completed */
 +
 +      /*
 +       * Now that updates are safely completed, we can perform
 +       * deletes. First delete the reflogs of any references that
 +       * will be deleted, since (in the unexpected event of an
 +       * error) leaving a reference without a reflog is less bad
 +       * than leaving a reflog without a reference (the latter is a
 +       * mildly invalid repository state):
 +       */
 +      for (i = 0; i < transaction->nr; i++) {
 +              struct ref_update *update = transaction->updates[i];
 +              if (update->flags & REF_DELETING &&
 +                  !(update->flags & REF_LOG_ONLY) &&
 +                  !(update->flags & REF_ISPRUNING)) {
 +                      strbuf_reset(&sb);
 +                      files_reflog_path(refs, &sb, update->refname);
 +                      if (!unlink_or_warn(sb.buf))
 +                              try_remove_empty_parents(refs, update->refname,
 +                                                       REMOVE_EMPTY_PARENTS_REFLOG);
 +              }
 +      }
 +
 +      /*
 +       * Perform deletes now that updates are safely completed.
 +       *
 +       * First delete any packed versions of the references, while
 +       * retaining the packed-refs lock:
 +       */
 +      if (packed_transaction) {
 +              ret = ref_transaction_commit(packed_transaction, err);
 +              ref_transaction_free(packed_transaction);
 +              packed_transaction = NULL;
 +              backend_data->packed_transaction = NULL;
 +              if (ret)
 +                      goto cleanup;
 +      }
 +
 +      /* Now delete the loose versions of the references: */
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
                struct ref_lock *lock = update->backend_data;
                                }
                                update->flags |= REF_DELETED_LOOSE;
                        }
 -
 -                      if (!(update->flags & REF_ISPRUNING))
 -                              string_list_append(&refs_to_delete,
 -                                                 lock->ref_name);
                }
        }
  
 -      if (repack_without_refs(refs, &refs_to_delete, err)) {
 -              ret = TRANSACTION_GENERIC_ERROR;
 -              goto cleanup;
 -      }
 -
 -      /* Delete the reflogs of any references that were deleted: */
 -      for_each_string_list_item(ref_to_delete, &refs_to_delete) {
 -              strbuf_reset(&sb);
 -              files_reflog_path(refs, &sb, ref_to_delete->string);
 -              if (!unlink_or_warn(sb.buf))
 -                      try_remove_empty_parents(refs, ref_to_delete->string,
 -                                               REMOVE_EMPTY_PARENTS_REFLOG);
 -      }
 -
        clear_loose_ref_cache(refs);
  
  cleanup:
 -      files_transaction_cleanup(transaction);
 +      files_transaction_cleanup(refs, transaction);
  
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
        }
  
        strbuf_release(&sb);
 -      string_list_clear(&refs_to_delete, 0);
        return ret;
  }
  
@@@ -2770,10 -3128,7 +2799,10 @@@ static int files_transaction_abort(stru
                                   struct ref_transaction *transaction,
                                   struct strbuf *err)
  {
 -      files_transaction_cleanup(transaction);
 +      struct files_ref_store *refs =
 +              files_downcast(ref_store, 0, "ref_transaction_abort");
 +
 +      files_transaction_cleanup(refs, transaction);
        return 0;
  }
  
@@@ -2795,7 -3150,6 +2824,7 @@@ static int files_initial_transaction_co
        size_t i;
        int ret = 0;
        struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
 +      struct ref_transaction *packed_transaction = NULL;
  
        assert(err);
  
                                 &affected_refnames))
                die("BUG: initial ref transaction called with existing refs");
  
 +      packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
 +      if (!packed_transaction) {
 +              ret = TRANSACTION_GENERIC_ERROR;
 +              goto cleanup;
 +      }
 +
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
  
                        ret = TRANSACTION_NAME_CONFLICT;
                        goto cleanup;
                }
 +
 +              /*
 +               * Add a reference creation for this reference to the
 +               * packed-refs transaction:
 +               */
 +              ref_transaction_add_update(packed_transaction, update->refname,
 +                                         update->flags & ~REF_HAVE_OLD,
 +                                         update->new_oid.hash, update->old_oid.hash,
 +                                         NULL);
        }
  
 -      if (lock_packed_refs(refs, 0)) {
 -              strbuf_addf(err, "unable to lock packed-refs file: %s",
 -                          strerror(errno));
 +      if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
                ret = TRANSACTION_GENERIC_ERROR;
                goto cleanup;
        }
  
 -      for (i = 0; i < transaction->nr; i++) {
 -              struct ref_update *update = transaction->updates[i];
 -
 -              if ((update->flags & REF_HAVE_NEW) &&
 -                  !is_null_oid(&update->new_oid))
 -                      add_packed_ref(refs, update->refname,
 -                                     &update->new_oid);
 -      }
 -
 -      if (commit_packed_refs(refs)) {
 -              strbuf_addf(err, "unable to commit packed-refs file: %s",
 -                          strerror(errno));
 +      if (initial_ref_transaction_commit(packed_transaction, err)) {
                ret = TRANSACTION_GENERIC_ERROR;
                goto cleanup;
        }
  
  cleanup:
 +      if (packed_transaction)
 +              ref_transaction_free(packed_transaction);
 +      packed_refs_unlock(refs->packed_ref_store);
        transaction->state = REF_TRANSACTION_CLOSED;
        string_list_clear(&affected_refnames, 0);
        return ret;
@@@ -2999,17 -3348,16 +3028,17 @@@ static int files_reflog_expire(struct r
                        !(type & REF_ISSYMREF) &&
                        !is_null_oid(&cb.last_kept_oid);
  
 -              if (close_lock_file(&reflog_lock)) {
 +              if (close_lock_file_gently(&reflog_lock)) {
                        status |= error("couldn't write %s: %s", log_file,
                                        strerror(errno));
 +                      rollback_lock_file(&reflog_lock);
                } else if (update &&
 -                         (write_in_full(get_lock_file_fd(lock->lk),
 -                              oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
 -                          write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
 -                          close_ref(lock) < 0)) {
 +                         (write_in_full(get_lock_file_fd(&lock->lk),
 +                              oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
 +                          write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 1 ||
 +                          close_ref_gently(lock) < 0)) {
                        status |= error("couldn't write %s",
 -                                      get_lock_file_path(lock->lk));
 +                                      get_lock_file_path(&lock->lk));
                        rollback_lock_file(&reflog_lock);
                } else if (commit_lock_file(&reflog_lock)) {
                        status |= error("unable to write reflog '%s' (%s)",
@@@ -3064,6 -3412,7 +3093,7 @@@ struct ref_storage_be refs_be_files = 
        files_create_symref,
        files_delete_refs,
        files_rename_ref,
+       files_copy_ref,
  
        files_ref_iterator_begin,
        files_read_raw_ref,
diff --combined refs/packed-backend.c
index 3bc47ffd5ea4e82f2505a8649b162d18ebf11a21,0000000000000000000000000000000000000000..9c0d685c7f4e8d770f151ddd9e0aeac48b9e252b
mode 100644,000000..100644
--- /dev/null
@@@ -1,1045 -1,0 +1,1053 @@@
 +#include "../cache.h"
 +#include "../config.h"
 +#include "../refs.h"
 +#include "refs-internal.h"
 +#include "ref-cache.h"
 +#include "packed-backend.h"
 +#include "../iterator.h"
 +#include "../lockfile.h"
 +
 +struct packed_ref_cache {
 +      struct ref_cache *cache;
 +
 +      /*
 +       * Count of references to the data structure in this instance,
 +       * including the pointer from files_ref_store::packed if any.
 +       * The data will not be freed as long as the reference count
 +       * is nonzero.
 +       */
 +      unsigned int referrers;
 +
 +      /* The metadata from when this packed-refs cache was read */
 +      struct stat_validity validity;
 +};
 +
 +/*
 + * Increment the reference count of *packed_refs.
 + */
 +static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
 +{
 +      packed_refs->referrers++;
 +}
 +
 +/*
 + * Decrease the reference count of *packed_refs.  If it goes to zero,
 + * free *packed_refs and return true; otherwise return false.
 + */
 +static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 +{
 +      if (!--packed_refs->referrers) {
 +              free_ref_cache(packed_refs->cache);
 +              stat_validity_clear(&packed_refs->validity);
 +              free(packed_refs);
 +              return 1;
 +      } else {
 +              return 0;
 +      }
 +}
 +
 +/*
 + * A container for `packed-refs`-related data. It is not (yet) a
 + * `ref_store`.
 + */
 +struct packed_ref_store {
 +      struct ref_store base;
 +
 +      unsigned int store_flags;
 +
 +      /* The path of the "packed-refs" file: */
 +      char *path;
 +
 +      /*
 +       * A cache of the values read from the `packed-refs` file, if
 +       * it might still be current; otherwise, NULL.
 +       */
 +      struct packed_ref_cache *cache;
 +
 +      /*
 +       * Lock used for the "packed-refs" file. Note that this (and
 +       * thus the enclosing `packed_ref_store`) must not be freed.
 +       */
 +      struct lock_file lock;
 +
 +      /*
 +       * Temporary file used when rewriting new contents to the
 +       * "packed-refs" file. Note that this (and thus the enclosing
 +       * `packed_ref_store`) must not be freed.
 +       */
 +      struct tempfile *tempfile;
 +};
 +
 +struct ref_store *packed_ref_store_create(const char *path,
 +                                        unsigned int store_flags)
 +{
 +      struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
 +      struct ref_store *ref_store = (struct ref_store *)refs;
 +
 +      base_ref_store_init(ref_store, &refs_be_packed);
 +      refs->store_flags = store_flags;
 +
 +      refs->path = xstrdup(path);
 +      return ref_store;
 +}
 +
 +/*
 + * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
 + * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
 + * support at least the flags specified in `required_flags`. `caller`
 + * is used in any necessary error messages.
 + */
 +static struct packed_ref_store *packed_downcast(struct ref_store *ref_store,
 +                                              unsigned int required_flags,
 +                                              const char *caller)
 +{
 +      struct packed_ref_store *refs;
 +
 +      if (ref_store->be != &refs_be_packed)
 +              die("BUG: ref_store is type \"%s\" not \"packed\" in %s",
 +                  ref_store->be->name, caller);
 +
 +      refs = (struct packed_ref_store *)ref_store;
 +
 +      if ((refs->store_flags & required_flags) != required_flags)
 +              die("BUG: unallowed operation (%s), requires %x, has %x\n",
 +                  caller, required_flags, refs->store_flags);
 +
 +      return refs;
 +}
 +
 +static void clear_packed_ref_cache(struct packed_ref_store *refs)
 +{
 +      if (refs->cache) {
 +              struct packed_ref_cache *cache = refs->cache;
 +
 +              refs->cache = NULL;
 +              release_packed_ref_cache(cache);
 +      }
 +}
 +
 +/* The length of a peeled reference line in packed-refs, including EOL: */
 +#define PEELED_LINE_LENGTH 42
 +
 +/*
 + * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 + * Return a pointer to the refname within the line (null-terminated),
 + * or NULL if there was a problem.
 + */
 +static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
 +{
 +      const char *ref;
 +
 +      if (parse_oid_hex(line->buf, oid, &ref) < 0)
 +              return NULL;
 +      if (!isspace(*ref++))
 +              return NULL;
 +
 +      if (isspace(*ref))
 +              return NULL;
 +
 +      if (line->buf[line->len - 1] != '\n')
 +              return NULL;
 +      line->buf[--line->len] = 0;
 +
 +      return ref;
 +}
 +
 +/*
 + * Read from `packed_refs_file` into a newly-allocated
 + * `packed_ref_cache` and return it. The return value will already
 + * have its reference count incremented.
 + *
 + * A comment line of the form "# pack-refs with: " may contain zero or
 + * more traits. We interpret the traits as follows:
 + *
 + *   No traits:
 + *
 + *      Probably no references are peeled. But if the file contains a
 + *      peeled value for a reference, we will use it.
 + *
 + *   peeled:
 + *
 + *      References under "refs/tags/", if they *can* be peeled, *are*
 + *      peeled in this file. References outside of "refs/tags/" are
 + *      probably not peeled even if they could have been, but if we find
 + *      a peeled value for such a reference we will use it.
 + *
 + *   fully-peeled:
 + *
 + *      All references in the file that can be peeled are peeled.
 + *      Inversely (and this is more important), any references in the
 + *      file for which no peeled value is recorded is not peelable. This
 + *      trait should typically be written alongside "peeled" for
 + *      compatibility with older clients, but we do not require it
 + *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
 + */
 +static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file)
 +{
 +      FILE *f;
 +      struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
 +      struct ref_entry *last = NULL;
 +      struct strbuf line = STRBUF_INIT;
 +      enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
 +      struct ref_dir *dir;
 +
 +      acquire_packed_ref_cache(packed_refs);
 +      packed_refs->cache = create_ref_cache(NULL, NULL);
 +      packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
 +
 +      f = fopen(packed_refs_file, "r");
 +      if (!f) {
 +              if (errno == ENOENT) {
 +                      /*
 +                       * This is OK; it just means that no
 +                       * "packed-refs" file has been written yet,
 +                       * which is equivalent to it being empty.
 +                       */
 +                      return packed_refs;
 +              } else {
 +                      die_errno("couldn't read %s", packed_refs_file);
 +              }
 +      }
 +
 +      stat_validity_update(&packed_refs->validity, fileno(f));
 +
 +      dir = get_ref_dir(packed_refs->cache->root);
 +      while (strbuf_getwholeline(&line, f, '\n') != EOF) {
 +              struct object_id oid;
 +              const char *refname;
 +              const char *traits;
 +
 +              if (!line.len || line.buf[line.len - 1] != '\n')
 +                      die("unterminated line in %s: %s", packed_refs_file, line.buf);
 +
 +              if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
 +                      if (strstr(traits, " fully-peeled "))
 +                              peeled = PEELED_FULLY;
 +                      else if (strstr(traits, " peeled "))
 +                              peeled = PEELED_TAGS;
 +                      /* perhaps other traits later as well */
 +                      continue;
 +              }
 +
 +              refname = parse_ref_line(&line, &oid);
 +              if (refname) {
 +                      int flag = REF_ISPACKED;
 +
 +                      if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 +                              if (!refname_is_safe(refname))
 +                                      die("packed refname is dangerous: %s", refname);
 +                              oidclr(&oid);
 +                              flag |= REF_BAD_NAME | REF_ISBROKEN;
 +                      }
 +                      last = create_ref_entry(refname, &oid, flag);
 +                      if (peeled == PEELED_FULLY ||
 +                          (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
 +                              last->flag |= REF_KNOWS_PEELED;
 +                      add_ref_entry(dir, last);
 +              } else if (last &&
 +                  line.buf[0] == '^' &&
 +                  line.len == PEELED_LINE_LENGTH &&
 +                  line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
 +                  !get_oid_hex(line.buf + 1, &oid)) {
 +                      oidcpy(&last->u.value.peeled, &oid);
 +                      /*
 +                       * Regardless of what the file header said,
 +                       * we definitely know the value of *this*
 +                       * reference:
 +                       */
 +                      last->flag |= REF_KNOWS_PEELED;
 +              } else {
 +                      strbuf_setlen(&line, line.len - 1);
 +                      die("unexpected line in %s: %s", packed_refs_file, line.buf);
 +              }
 +      }
 +
 +      fclose(f);
 +      strbuf_release(&line);
 +
 +      return packed_refs;
 +}
 +
 +/*
 + * Check that the packed refs cache (if any) still reflects the
 + * contents of the file. If not, clear the cache.
 + */
 +static void validate_packed_ref_cache(struct packed_ref_store *refs)
 +{
 +      if (refs->cache &&
 +          !stat_validity_check(&refs->cache->validity, refs->path))
 +              clear_packed_ref_cache(refs);
 +}
 +
 +/*
 + * Get the packed_ref_cache for the specified packed_ref_store,
 + * creating and populating it if it hasn't been read before or if the
 + * file has been changed (according to its `validity` field) since it
 + * was last read. On the other hand, if we hold the lock, then assume
 + * that the file hasn't been changed out from under us, so skip the
 + * extra `stat()` call in `stat_validity_check()`.
 + */
 +static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *refs)
 +{
 +      if (!is_lock_file_locked(&refs->lock))
 +              validate_packed_ref_cache(refs);
 +
 +      if (!refs->cache)
 +              refs->cache = read_packed_refs(refs->path);
 +
 +      return refs->cache;
 +}
 +
 +static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
 +{
 +      return get_ref_dir(packed_ref_cache->cache->root);
 +}
 +
 +static struct ref_dir *get_packed_refs(struct packed_ref_store *refs)
 +{
 +      return get_packed_ref_dir(get_packed_ref_cache(refs));
 +}
 +
 +/*
 + * Return the ref_entry for the given refname from the packed
 + * references.  If it does not exist, return NULL.
 + */
 +static struct ref_entry *get_packed_ref(struct packed_ref_store *refs,
 +                                      const char *refname)
 +{
 +      return find_ref_entry(get_packed_refs(refs), refname);
 +}
 +
 +static int packed_read_raw_ref(struct ref_store *ref_store,
 +                             const char *refname, unsigned char *sha1,
 +                             struct strbuf *referent, unsigned int *type)
 +{
 +      struct packed_ref_store *refs =
 +              packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
 +
 +      struct ref_entry *entry;
 +
 +      *type = 0;
 +
 +      entry = get_packed_ref(refs, refname);
 +      if (!entry) {
 +              errno = ENOENT;
 +              return -1;
 +      }
 +
 +      hashcpy(sha1, entry->u.value.oid.hash);
 +      *type = REF_ISPACKED;
 +      return 0;
 +}
 +
 +static int packed_peel_ref(struct ref_store *ref_store,
 +                         const char *refname, unsigned char *sha1)
 +{
 +      struct packed_ref_store *refs =
 +              packed_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
 +                              "peel_ref");
 +      struct ref_entry *r = get_packed_ref(refs, refname);
 +
 +      if (!r || peel_entry(r, 0))
 +              return -1;
 +
 +      hashcpy(sha1, r->u.value.peeled.hash);
 +      return 0;
 +}
 +
 +struct packed_ref_iterator {
 +      struct ref_iterator base;
 +
 +      struct packed_ref_cache *cache;
 +      struct ref_iterator *iter0;
 +      unsigned int flags;
 +};
 +
 +static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
 +{
 +      struct packed_ref_iterator *iter =
 +              (struct packed_ref_iterator *)ref_iterator;
 +      int ok;
 +
 +      while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
 +              if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 +                  ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
 +                      continue;
 +
 +              if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 +                  !ref_resolves_to_object(iter->iter0->refname,
 +                                          iter->iter0->oid,
 +                                          iter->iter0->flags))
 +                      continue;
 +
 +              iter->base.refname = iter->iter0->refname;
 +              iter->base.oid = iter->iter0->oid;
 +              iter->base.flags = iter->iter0->flags;
 +              return ITER_OK;
 +      }
 +
 +      iter->iter0 = NULL;
 +      if (ref_iterator_abort(ref_iterator) != ITER_DONE)
 +              ok = ITER_ERROR;
 +
 +      return ok;
 +}
 +
 +static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
 +                                 struct object_id *peeled)
 +{
 +      struct packed_ref_iterator *iter =
 +              (struct packed_ref_iterator *)ref_iterator;
 +
 +      return ref_iterator_peel(iter->iter0, peeled);
 +}
 +
 +static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
 +{
 +      struct packed_ref_iterator *iter =
 +              (struct packed_ref_iterator *)ref_iterator;
 +      int ok = ITER_DONE;
 +
 +      if (iter->iter0)
 +              ok = ref_iterator_abort(iter->iter0);
 +
 +      release_packed_ref_cache(iter->cache);
 +      base_ref_iterator_free(ref_iterator);
 +      return ok;
 +}
 +
 +static struct ref_iterator_vtable packed_ref_iterator_vtable = {
 +      packed_ref_iterator_advance,
 +      packed_ref_iterator_peel,
 +      packed_ref_iterator_abort
 +};
 +
 +static struct ref_iterator *packed_ref_iterator_begin(
 +              struct ref_store *ref_store,
 +              const char *prefix, unsigned int flags)
 +{
 +      struct packed_ref_store *refs;
 +      struct packed_ref_iterator *iter;
 +      struct ref_iterator *ref_iterator;
 +      unsigned int required_flags = REF_STORE_READ;
 +
 +      if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
 +              required_flags |= REF_STORE_ODB;
 +      refs = packed_downcast(ref_store, required_flags, "ref_iterator_begin");
 +
 +      iter = xcalloc(1, sizeof(*iter));
 +      ref_iterator = &iter->base;
 +      base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable);
 +
 +      /*
 +       * Note that get_packed_ref_cache() internally checks whether
 +       * the packed-ref cache is up to date with what is on disk,
 +       * and re-reads it if not.
 +       */
 +
 +      iter->cache = get_packed_ref_cache(refs);
 +      acquire_packed_ref_cache(iter->cache);
 +      iter->iter0 = cache_ref_iterator_begin(iter->cache->cache, prefix, 0);
 +
 +      iter->flags = flags;
 +
 +      return ref_iterator;
 +}
 +
 +/*
 + * Write an entry to the packed-refs file for the specified refname.
 + * If peeled is non-NULL, write it as the entry's peeled value. On
 + * error, return a nonzero value and leave errno set at the value left
 + * by the failing call to `fprintf()`.
 + */
 +static int write_packed_entry(FILE *fh, const char *refname,
 +                            const unsigned char *sha1,
 +                            const unsigned char *peeled)
 +{
 +      if (fprintf(fh, "%s %s\n", sha1_to_hex(sha1), refname) < 0 ||
 +          (peeled && fprintf(fh, "^%s\n", sha1_to_hex(peeled)) < 0))
 +              return -1;
 +
 +      return 0;
 +}
 +
 +int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
 +{
 +      struct packed_ref_store *refs =
 +              packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
 +                              "packed_refs_lock");
 +      static int timeout_configured = 0;
 +      static int timeout_value = 1000;
 +
 +      if (!timeout_configured) {
 +              git_config_get_int("core.packedrefstimeout", &timeout_value);
 +              timeout_configured = 1;
 +      }
 +
 +      /*
 +       * Note that we close the lockfile immediately because we
 +       * don't write new content to it, but rather to a separate
 +       * tempfile.
 +       */
 +      if (hold_lock_file_for_update_timeout(
 +                          &refs->lock,
 +                          refs->path,
 +                          flags, timeout_value) < 0) {
 +              unable_to_lock_message(refs->path, errno, err);
 +              return -1;
 +      }
 +
 +      if (close_lock_file_gently(&refs->lock)) {
 +              strbuf_addf(err, "unable to close %s: %s", refs->path, strerror(errno));
 +              rollback_lock_file(&refs->lock);
 +              return -1;
 +      }
 +
 +      /*
 +       * Now that we hold the `packed-refs` lock, make sure that our
 +       * cache matches the current version of the file. Normally
 +       * `get_packed_ref_cache()` does that for us, but that
 +       * function assumes that when the file is locked, any existing
 +       * cache is still valid. We've just locked the file, but it
 +       * might have changed the moment *before* we locked it.
 +       */
 +      validate_packed_ref_cache(refs);
 +
 +      /*
 +       * Now make sure that the packed-refs file as it exists in the
 +       * locked state is loaded into the cache:
 +       */
 +      get_packed_ref_cache(refs);
 +      return 0;
 +}
 +
 +void packed_refs_unlock(struct ref_store *ref_store)
 +{
 +      struct packed_ref_store *refs = packed_downcast(
 +                      ref_store,
 +                      REF_STORE_READ | REF_STORE_WRITE,
 +                      "packed_refs_unlock");
 +
 +      if (!is_lock_file_locked(&refs->lock))
 +              die("BUG: packed_refs_unlock() called when not locked");
 +      rollback_lock_file(&refs->lock);
 +}
 +
 +int packed_refs_is_locked(struct ref_store *ref_store)
 +{
 +      struct packed_ref_store *refs = packed_downcast(
 +                      ref_store,
 +                      REF_STORE_READ | REF_STORE_WRITE,
 +                      "packed_refs_is_locked");
 +
 +      return is_lock_file_locked(&refs->lock);
 +}
 +
 +/*
 + * The packed-refs header line that we write out.  Perhaps other
 + * traits will be added later.  The trailing space is required.
 + */
 +static const char PACKED_REFS_HEADER[] =
 +      "# pack-refs with: peeled fully-peeled \n";
 +
 +static int packed_init_db(struct ref_store *ref_store, struct strbuf *err)
 +{
 +      /* Nothing to do. */
 +      return 0;
 +}
 +
 +/*
 + * Write the packed-refs from the cache to the packed-refs tempfile,
 + * incorporating any changes from `updates`. `updates` must be a
 + * sorted string list whose keys are the refnames and whose util
 + * values are `struct ref_update *`. On error, rollback the tempfile,
 + * write an error message to `err`, and return a nonzero value.
 + *
 + * The packfile must be locked before calling this function and will
 + * remain locked when it is done.
 + */
 +static int write_with_updates(struct packed_ref_store *refs,
 +                            struct string_list *updates,
 +                            struct strbuf *err)
 +{
 +      struct ref_iterator *iter = NULL;
 +      size_t i;
 +      int ok;
 +      FILE *out;
 +      struct strbuf sb = STRBUF_INIT;
 +      char *packed_refs_path;
 +
 +      if (!is_lock_file_locked(&refs->lock))
 +              die("BUG: write_with_updates() called while unlocked");
 +
 +      /*
 +       * If packed-refs is a symlink, we want to overwrite the
 +       * symlinked-to file, not the symlink itself. Also, put the
 +       * staging file next to it:
 +       */
 +      packed_refs_path = get_locked_file_path(&refs->lock);
 +      strbuf_addf(&sb, "%s.new", packed_refs_path);
 +      free(packed_refs_path);
 +      refs->tempfile = create_tempfile(sb.buf);
 +      if (!refs->tempfile) {
 +              strbuf_addf(err, "unable to create file %s: %s",
 +                          sb.buf, strerror(errno));
 +              strbuf_release(&sb);
 +              return -1;
 +      }
 +      strbuf_release(&sb);
 +
 +      out = fdopen_tempfile(refs->tempfile, "w");
 +      if (!out) {
 +              strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s",
 +                          strerror(errno));
 +              goto error;
 +      }
 +
 +      if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0)
 +              goto write_error;
 +
 +      /*
 +       * We iterate in parallel through the current list of refs and
 +       * the list of updates, processing an entry from at least one
 +       * of the lists each time through the loop. When the current
 +       * list of refs is exhausted, set iter to NULL. When the list
 +       * of updates is exhausted, leave i set to updates->nr.
 +       */
 +      iter = packed_ref_iterator_begin(&refs->base, "",
 +                                       DO_FOR_EACH_INCLUDE_BROKEN);
 +      if ((ok = ref_iterator_advance(iter)) != ITER_OK)
 +              iter = NULL;
 +
 +      i = 0;
 +
 +      while (iter || i < updates->nr) {
 +              struct ref_update *update = NULL;
 +              int cmp;
 +
 +              if (i >= updates->nr) {
 +                      cmp = -1;
 +              } else {
 +                      update = updates->items[i].util;
 +
 +                      if (!iter)
 +                              cmp = +1;
 +                      else
 +                              cmp = strcmp(iter->refname, update->refname);
 +              }
 +
 +              if (!cmp) {
 +                      /*
 +                       * There is both an old value and an update
 +                       * for this reference. Check the old value if
 +                       * necessary:
 +                       */
 +                      if ((update->flags & REF_HAVE_OLD)) {
 +                              if (is_null_oid(&update->old_oid)) {
 +                                      strbuf_addf(err, "cannot update ref '%s': "
 +                                                  "reference already exists",
 +                                                  update->refname);
 +                                      goto error;
 +                              } else if (oidcmp(&update->old_oid, iter->oid)) {
 +                                      strbuf_addf(err, "cannot update ref '%s': "
 +                                                  "is at %s but expected %s",
 +                                                  update->refname,
 +                                                  oid_to_hex(iter->oid),
 +                                                  oid_to_hex(&update->old_oid));
 +                                      goto error;
 +                              }
 +                      }
 +
 +                      /* Now figure out what to use for the new value: */
 +                      if ((update->flags & REF_HAVE_NEW)) {
 +                              /*
 +                               * The update takes precedence. Skip
 +                               * the iterator over the unneeded
 +                               * value.
 +                               */
 +                              if ((ok = ref_iterator_advance(iter)) != ITER_OK)
 +                                      iter = NULL;
 +                              cmp = +1;
 +                      } else {
 +                              /*
 +                               * The update doesn't actually want to
 +                               * change anything. We're done with it.
 +                               */
 +                              i++;
 +                              cmp = -1;
 +                      }
 +              } else if (cmp > 0) {
 +                      /*
 +                       * There is no old value but there is an
 +                       * update for this reference. Make sure that
 +                       * the update didn't expect an existing value:
 +                       */
 +                      if ((update->flags & REF_HAVE_OLD) &&
 +                          !is_null_oid(&update->old_oid)) {
 +                              strbuf_addf(err, "cannot update ref '%s': "
 +                                          "reference is missing but expected %s",
 +                                          update->refname,
 +                                          oid_to_hex(&update->old_oid));
 +                              goto error;
 +                      }
 +              }
 +
 +              if (cmp < 0) {
 +                      /* Pass the old reference through. */
 +
 +                      struct object_id peeled;
 +                      int peel_error = ref_iterator_peel(iter, &peeled);
 +
 +                      if (write_packed_entry(out, iter->refname,
 +                                             iter->oid->hash,
 +                                             peel_error ? NULL : peeled.hash))
 +                              goto write_error;
 +
 +                      if ((ok = ref_iterator_advance(iter)) != ITER_OK)
 +                              iter = NULL;
 +              } else if (is_null_oid(&update->new_oid)) {
 +                      /*
 +                       * The update wants to delete the reference,
 +                       * and the reference either didn't exist or we
 +                       * have already skipped it. So we're done with
 +                       * the update (and don't have to write
 +                       * anything).
 +                       */
 +                      i++;
 +              } else {
 +                      struct object_id peeled;
 +                      int peel_error = peel_object(update->new_oid.hash,
 +                                                   peeled.hash);
 +
 +                      if (write_packed_entry(out, update->refname,
 +                                             update->new_oid.hash,
 +                                             peel_error ? NULL : peeled.hash))
 +                              goto write_error;
 +
 +                      i++;
 +              }
 +      }
 +
 +      if (ok != ITER_DONE) {
 +              strbuf_addf(err, "unable to write packed-refs file: "
 +                          "error iterating over old contents");
 +              goto error;
 +      }
 +
 +      if (close_tempfile_gently(refs->tempfile)) {
 +              strbuf_addf(err, "error closing file %s: %s",
 +                          get_tempfile_path(refs->tempfile),
 +                          strerror(errno));
 +              strbuf_release(&sb);
 +              delete_tempfile(&refs->tempfile);
 +              return -1;
 +      }
 +
 +      return 0;
 +
 +write_error:
 +      strbuf_addf(err, "error writing to %s: %s",
 +                  get_tempfile_path(refs->tempfile), strerror(errno));
 +
 +error:
 +      if (iter)
 +              ref_iterator_abort(iter);
 +
 +      delete_tempfile(&refs->tempfile);
 +      return -1;
 +}
 +
 +struct packed_transaction_backend_data {
 +      /* True iff the transaction owns the packed-refs lock. */
 +      int own_lock;
 +
 +      struct string_list updates;
 +};
 +
 +static void packed_transaction_cleanup(struct packed_ref_store *refs,
 +                                     struct ref_transaction *transaction)
 +{
 +      struct packed_transaction_backend_data *data = transaction->backend_data;
 +
 +      if (data) {
 +              string_list_clear(&data->updates, 0);
 +
 +              if (is_tempfile_active(refs->tempfile))
 +                      delete_tempfile(&refs->tempfile);
 +
 +              if (data->own_lock && is_lock_file_locked(&refs->lock)) {
 +                      packed_refs_unlock(&refs->base);
 +                      data->own_lock = 0;
 +              }
 +
 +              free(data);
 +              transaction->backend_data = NULL;
 +      }
 +
 +      transaction->state = REF_TRANSACTION_CLOSED;
 +}
 +
 +static int packed_transaction_prepare(struct ref_store *ref_store,
 +                                    struct ref_transaction *transaction,
 +                                    struct strbuf *err)
 +{
 +      struct packed_ref_store *refs = packed_downcast(
 +                      ref_store,
 +                      REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
 +                      "ref_transaction_prepare");
 +      struct packed_transaction_backend_data *data;
 +      size_t i;
 +      int ret = TRANSACTION_GENERIC_ERROR;
 +
 +      /*
 +       * Note that we *don't* skip transactions with zero updates,
 +       * because such a transaction might be executed for the side
 +       * effect of ensuring that all of the references are peeled.
 +       * If the caller wants to optimize away empty transactions, it
 +       * should do so itself.
 +       */
 +
 +      data = xcalloc(1, sizeof(*data));
 +      string_list_init(&data->updates, 0);
 +
 +      transaction->backend_data = data;
 +
 +      /*
 +       * Stick the updates in a string list by refname so that we
 +       * can sort them:
 +       */
 +      for (i = 0; i < transaction->nr; i++) {
 +              struct ref_update *update = transaction->updates[i];
 +              struct string_list_item *item =
 +                      string_list_append(&data->updates, update->refname);
 +
 +              /* Store a pointer to update in item->util: */
 +              item->util = update;
 +      }
 +      string_list_sort(&data->updates);
 +
 +      if (ref_update_reject_duplicates(&data->updates, err))
 +              goto failure;
 +
 +      if (!is_lock_file_locked(&refs->lock)) {
 +              if (packed_refs_lock(ref_store, 0, err))
 +                      goto failure;
 +              data->own_lock = 1;
 +      }
 +
 +      if (write_with_updates(refs, &data->updates, err))
 +              goto failure;
 +
 +      transaction->state = REF_TRANSACTION_PREPARED;
 +      return 0;
 +
 +failure:
 +      packed_transaction_cleanup(refs, transaction);
 +      return ret;
 +}
 +
 +static int packed_transaction_abort(struct ref_store *ref_store,
 +                                  struct ref_transaction *transaction,
 +                                  struct strbuf *err)
 +{
 +      struct packed_ref_store *refs = packed_downcast(
 +                      ref_store,
 +                      REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
 +                      "ref_transaction_abort");
 +
 +      packed_transaction_cleanup(refs, transaction);
 +      return 0;
 +}
 +
 +static int packed_transaction_finish(struct ref_store *ref_store,
 +                                   struct ref_transaction *transaction,
 +                                   struct strbuf *err)
 +{
 +      struct packed_ref_store *refs = packed_downcast(
 +                      ref_store,
 +                      REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
 +                      "ref_transaction_finish");
 +      int ret = TRANSACTION_GENERIC_ERROR;
 +      char *packed_refs_path;
 +
 +      packed_refs_path = get_locked_file_path(&refs->lock);
 +      if (rename_tempfile(&refs->tempfile, packed_refs_path)) {
 +              strbuf_addf(err, "error replacing %s: %s",
 +                          refs->path, strerror(errno));
 +              goto cleanup;
 +      }
 +
 +      clear_packed_ref_cache(refs);
 +      ret = 0;
 +
 +cleanup:
 +      free(packed_refs_path);
 +      packed_transaction_cleanup(refs, transaction);
 +      return ret;
 +}
 +
 +static int packed_initial_transaction_commit(struct ref_store *ref_store,
 +                                          struct ref_transaction *transaction,
 +                                          struct strbuf *err)
 +{
 +      return ref_transaction_commit(transaction, err);
 +}
 +
 +static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 +                           struct string_list *refnames, unsigned int flags)
 +{
 +      struct packed_ref_store *refs =
 +              packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
 +      struct strbuf err = STRBUF_INIT;
 +      struct ref_transaction *transaction;
 +      struct string_list_item *item;
 +      int ret;
 +
 +      (void)refs; /* We need the check above, but don't use the variable */
 +
 +      if (!refnames->nr)
 +              return 0;
 +
 +      /*
 +       * Since we don't check the references' old_oids, the
 +       * individual updates can't fail, so we can pack all of the
 +       * updates into a single transaction.
 +       */
 +
 +      transaction = ref_store_transaction_begin(ref_store, &err);
 +      if (!transaction)
 +              return -1;
 +
 +      for_each_string_list_item(item, refnames) {
 +              if (ref_transaction_delete(transaction, item->string, NULL,
 +                                         flags, msg, &err)) {
 +                      warning(_("could not delete reference %s: %s"),
 +                              item->string, err.buf);
 +                      strbuf_reset(&err);
 +              }
 +      }
 +
 +      ret = ref_transaction_commit(transaction, &err);
 +
 +      if (ret) {
 +              if (refnames->nr == 1)
 +                      error(_("could not delete reference %s: %s"),
 +                            refnames->items[0].string, err.buf);
 +              else
 +                      error(_("could not delete references: %s"), err.buf);
 +      }
 +
 +      ref_transaction_free(transaction);
 +      strbuf_release(&err);
 +      return ret;
 +}
 +
 +static int packed_pack_refs(struct ref_store *ref_store, unsigned int flags)
 +{
 +      /*
 +       * Packed refs are already packed. It might be that loose refs
 +       * are packed *into* a packed refs store, but that is done by
 +       * updating the packed references via a transaction.
 +       */
 +      return 0;
 +}
 +
 +static int packed_create_symref(struct ref_store *ref_store,
 +                             const char *refname, const char *target,
 +                             const char *logmsg)
 +{
 +      die("BUG: packed reference store does not support symrefs");
 +}
 +
 +static int packed_rename_ref(struct ref_store *ref_store,
 +                          const char *oldrefname, const char *newrefname,
 +                          const char *logmsg)
 +{
 +      die("BUG: packed reference store does not support renaming references");
 +}
 +
++static int packed_copy_ref(struct ref_store *ref_store,
++                         const char *oldrefname, const char *newrefname,
++                         const char *logmsg)
++{
++      die("BUG: packed reference store does not support copying references");
++}
++
 +static struct ref_iterator *packed_reflog_iterator_begin(struct ref_store *ref_store)
 +{
 +      return empty_ref_iterator_begin();
 +}
 +
 +static int packed_for_each_reflog_ent(struct ref_store *ref_store,
 +                                    const char *refname,
 +                                    each_reflog_ent_fn fn, void *cb_data)
 +{
 +      return 0;
 +}
 +
 +static int packed_for_each_reflog_ent_reverse(struct ref_store *ref_store,
 +                                            const char *refname,
 +                                            each_reflog_ent_fn fn,
 +                                            void *cb_data)
 +{
 +      return 0;
 +}
 +
 +static int packed_reflog_exists(struct ref_store *ref_store,
 +                             const char *refname)
 +{
 +      return 0;
 +}
 +
 +static int packed_create_reflog(struct ref_store *ref_store,
 +                             const char *refname, int force_create,
 +                             struct strbuf *err)
 +{
 +      die("BUG: packed reference store does not support reflogs");
 +}
 +
 +static int packed_delete_reflog(struct ref_store *ref_store,
 +                             const char *refname)
 +{
 +      return 0;
 +}
 +
 +static int packed_reflog_expire(struct ref_store *ref_store,
 +                              const char *refname, const unsigned char *sha1,
 +                              unsigned int flags,
 +                              reflog_expiry_prepare_fn prepare_fn,
 +                              reflog_expiry_should_prune_fn should_prune_fn,
 +                              reflog_expiry_cleanup_fn cleanup_fn,
 +                              void *policy_cb_data)
 +{
 +      return 0;
 +}
 +
 +struct ref_storage_be refs_be_packed = {
 +      NULL,
 +      "packed",
 +      packed_ref_store_create,
 +      packed_init_db,
 +      packed_transaction_prepare,
 +      packed_transaction_finish,
 +      packed_transaction_abort,
 +      packed_initial_transaction_commit,
 +
 +      packed_pack_refs,
 +      packed_peel_ref,
 +      packed_create_symref,
 +      packed_delete_refs,
 +      packed_rename_ref,
++      packed_copy_ref,
 +
 +      packed_ref_iterator_begin,
 +      packed_read_raw_ref,
 +
 +      packed_reflog_iterator_begin,
 +      packed_for_each_reflog_ent,
 +      packed_for_each_reflog_ent_reverse,
 +      packed_reflog_exists,
 +      packed_create_reflog,
 +      packed_delete_reflog,
 +      packed_reflog_expire
 +};
diff --combined refs/refs-internal.h
index d7d344de73e6f85fed1e8460bce246a894eab6da,3c51194edb1904e4debc9beb81a9f876208dd03e..8821e27ed9c033d36caceefc9cd1242682ae9398
   */
  #define REF_DELETED_LOOSE 0x200
  
 +/*
 + * Return the length of time to retry acquiring a loose reference lock
 + * before giving up, in milliseconds:
 + */
 +long get_files_ref_lock_timeout_ms(void);
 +
  /*
   * Return true iff refname is minimally safe. "Safe" here means that
   * deleting a loose reference by this name will not do any damage, for
   */
  int refname_is_safe(const char *refname);
  
 +/*
 + * Helper function: return true if refname, which has the specified
 + * oid and flags, can be resolved to an object in the database. If the
 + * referred-to object does not exist, emit a warning and return false.
 + */
 +int ref_resolves_to_object(const char *refname,
 +                         const struct object_id *oid,
 +                         unsigned int flags);
 +
  enum peel_status {
        /* object was peeled successfully: */
        PEEL_PEELED = 0,
@@@ -242,7 -227,6 +242,7 @@@ struct ref_transaction 
        size_t alloc;
        size_t nr;
        enum ref_transaction_state state;
 +      void *backend_data;
  };
  
  /*
@@@ -559,6 -543,9 +559,9 @@@ typedef int delete_refs_fn(struct ref_s
  typedef int rename_ref_fn(struct ref_store *ref_store,
                          const char *oldref, const char *newref,
                          const char *logmsg);
+ typedef int copy_ref_fn(struct ref_store *ref_store,
+                         const char *oldref, const char *newref,
+                         const char *logmsg);
  
  /*
   * Iterate over the references in `ref_store` whose names start with
@@@ -657,6 -644,7 +660,7 @@@ struct ref_storage_be 
        create_symref_fn *create_symref;
        delete_refs_fn *delete_refs;
        rename_ref_fn *rename_ref;
+       copy_ref_fn *copy_ref;
  
        ref_iterator_begin_fn *iterator_begin;
        read_raw_ref_fn *read_raw_ref;
  };
  
  extern struct ref_storage_be refs_be_files;
 +extern struct ref_storage_be refs_be_packed;
  
  /*
   * A representation of the reference store for the main repository or
diff --combined t/t3200-branch.sh
index d971649979fa2661923d9df797125cd4d997cf97,e286ddaf2314bc64bd515b6ba44089dc7098fe6d..3ac7ebf85f3198cde56f784456e0024205aec853
@@@ -100,23 -100,6 +100,23 @@@ test_expect_success 'git branch -m n/n 
        git reflog exists refs/heads/n
  '
  
 +# The topmost entry in reflog for branch bbb is about branch creation.
 +# Hence, we compare bbb@{1} (instead of bbb@{0}) with aaa@{0}.
 +
 +test_expect_success 'git branch -m bbb should rename checked out branch' '
 +      test_when_finished git branch -D bbb &&
 +      test_when_finished git checkout master &&
 +      git checkout -b aaa &&
 +      git commit --allow-empty -m "a new commit" &&
 +      git rev-parse aaa@{0} >expect &&
 +      git branch -m bbb &&
 +      git rev-parse bbb@{1} >actual &&
 +      test_cmp expect actual &&
 +      git symbolic-ref HEAD >actual &&
 +      echo refs/heads/bbb >expect &&
 +      test_cmp expect actual
 +'
 +
  test_expect_success 'git branch -m o/o o should fail when o/p exists' '
        git branch o/o &&
        git branch o/p &&
@@@ -162,29 -145,6 +162,29 @@@ test_expect_success 'git branch -M baz 
        grep "^0\{40\}.*$msg$" .git/logs/HEAD
  '
  
 +test_expect_success 'git branch -M should leave orphaned HEAD alone' '
 +      git init orphan &&
 +      (
 +              cd orphan &&
 +              test_commit initial &&
 +              git checkout --orphan lonely &&
 +              grep lonely .git/HEAD &&
 +              test_path_is_missing .git/refs/head/lonely &&
 +              git branch -M master mistress &&
 +              grep lonely .git/HEAD
 +      )
 +'
 +
 +test_expect_success 'resulting reflog can be shown by log -g' '
 +      oid=$(git rev-parse HEAD) &&
 +      cat >expect <<-EOF &&
 +      HEAD@{0} $oid $msg
 +      HEAD@{2} $oid checkout: moving from foo to baz
 +      EOF
 +      git log -g --format="%gd %H %gs" -2 HEAD >actual &&
 +      test_cmp expect actual
 +'
 +
  test_expect_success 'git branch -M baz bam should succeed when baz is checked out as linked working tree' '
        git checkout master &&
        git worktree add -b baz bazdir &&
@@@ -381,6 -341,262 +381,262 @@@ test_expect_success 'config informatio
        test_must_fail git config branch.s/s.dummy
  '
  
+ test_expect_success 'git branch -m correctly renames multiple config sections' '
+       test_when_finished "git checkout master" &&
+       git checkout -b source master &&
+       # Assert that a config file with multiple config sections has
+       # those sections preserved...
+       cat >expect <<-\EOF &&
+       branch.dest.key1=value1
+       some.gar.b=age
+       branch.dest.key2=value2
+       EOF
+       cat >config.branch <<\EOF &&
+ ;; Note the lack of -\EOF above & mixed indenting here. This is
+ ;; intentional, we are also testing that the formatting of copied
+ ;; sections is preserved.
+ ;; Comment for source. Tabs
+ [branch "source"]
+       ;; Comment for the source value
+       key1 = value1
+ ;; Comment for some.gar. Spaces
+ [some "gar"]
+     ;; Comment for the some.gar value
+     b = age
+ ;; Comment for source, again. Mixed tabs/spaces.
+ [branch "source"]
+     ;; Comment for the source value, again
+       key2 = value2
+ EOF
+       cat config.branch >>.git/config &&
+       git branch -m source dest &&
+       git config -f .git/config -l | grep -F -e source -e dest -e some.gar >actual &&
+       test_cmp expect actual &&
+       # ...and that the comments for those sections are also
+       # preserved.
+       cat config.branch | sed "s/\"source\"/\"dest\"/" >expect &&
+       sed -n -e "/Note the lack/,\$p" .git/config >actual &&
+       test_cmp expect actual
+ '
+ test_expect_success 'git branch -c dumps usage' '
+       test_expect_code 128 git branch -c 2>err &&
+       test_i18ngrep "branch name required" err
+ '
+ test_expect_success 'git branch --copy dumps usage' '
+       test_expect_code 128 git branch --copy 2>err &&
+       test_i18ngrep "branch name required" err
+ '
+ test_expect_success 'git branch -c d e should work' '
+       git branch -l d &&
+       git reflog exists refs/heads/d &&
+       git config branch.d.dummy Hello &&
+       git branch -c d e &&
+       git reflog exists refs/heads/d &&
+       git reflog exists refs/heads/e &&
+       echo Hello >expect &&
+       git config branch.e.dummy >actual &&
+       test_cmp expect actual &&
+       echo Hello >expect &&
+       git config branch.d.dummy >actual &&
+       test_cmp expect actual
+ '
+ test_expect_success 'git branch --copy is a synonym for -c' '
+       git branch -l copy &&
+       git reflog exists refs/heads/copy &&
+       git config branch.copy.dummy Hello &&
+       git branch --copy copy copy-to &&
+       git reflog exists refs/heads/copy &&
+       git reflog exists refs/heads/copy-to &&
+       echo Hello >expect &&
+       git config branch.copy.dummy >actual &&
+       test_cmp expect actual &&
+       echo Hello >expect &&
+       git config branch.copy-to.dummy >actual &&
+       test_cmp expect actual
+ '
+ test_expect_success 'git branch -c ee ef should copy ee to create branch ef' '
+       git checkout -b ee &&
+       git reflog exists refs/heads/ee &&
+       git config branch.ee.dummy Hello &&
+       git branch -c ee ef &&
+       git reflog exists refs/heads/ee &&
+       git reflog exists refs/heads/ef &&
+       test $(git config branch.ee.dummy) = Hello &&
+       test $(git config branch.ef.dummy) = Hello &&
+       test $(git rev-parse --abbrev-ref HEAD) = ee
+ '
+ test_expect_success 'git branch -c f/f g/g should work' '
+       git branch -l f/f &&
+       git reflog exists refs/heads/f/f &&
+       git config branch.f/f.dummy Hello &&
+       git branch -c f/f g/g &&
+       git reflog exists refs/heads/f/f &&
+       git reflog exists refs/heads/g/g &&
+       test $(git config branch.f/f.dummy) = Hello &&
+       test $(git config branch.g/g.dummy) = Hello
+ '
+ test_expect_success 'git branch -c m2 m2 should work' '
+       git branch -l m2 &&
+       git reflog exists refs/heads/m2 &&
+       git config branch.m2.dummy Hello &&
+       git branch -c m2 m2 &&
+       git reflog exists refs/heads/m2 &&
+       test $(git config branch.m2.dummy) = Hello
+ '
+ test_expect_success 'git branch -c zz zz/zz should fail' '
+       git branch -l zz &&
+       git reflog exists refs/heads/zz &&
+       test_must_fail git branch -c zz zz/zz
+ '
+ test_expect_success 'git branch -c b/b b should fail' '
+       git branch -l b/b &&
+       test_must_fail git branch -c b/b b
+ '
+ test_expect_success 'git branch -C o/q o/p should work when o/p exists' '
+       git branch -l o/q &&
+       git reflog exists refs/heads/o/q &&
+       git reflog exists refs/heads/o/p &&
+       git branch -C o/q o/p
+ '
+ test_expect_success 'git branch -c -f o/q o/p should work when o/p exists' '
+       git reflog exists refs/heads/o/q &&
+       git reflog exists refs/heads/o/p &&
+       git branch -c -f o/q o/p
+ '
+ test_expect_success 'git branch -c qq rr/qq should fail when r exists' '
+       git branch qq &&
+       git branch rr &&
+       test_must_fail git branch -c qq rr/qq
+ '
+ test_expect_success 'git branch -C b1 b2 should fail when b2 is checked out' '
+       git branch b1 &&
+       git checkout -b b2 &&
+       test_must_fail git branch -C b1 b2
+ '
+ test_expect_success 'git branch -C c1 c2 should succeed when c1 is checked out' '
+       git checkout -b c1 &&
+       git branch c2 &&
+       git branch -C c1 c2 &&
+       test $(git rev-parse --abbrev-ref HEAD) = c1
+ '
+ test_expect_success 'git branch -C c1 c2 should never touch HEAD' '
+       msg="Branch: copied refs/heads/c1 to refs/heads/c2" &&
+       ! grep "$msg$" .git/logs/HEAD
+ '
+ test_expect_success 'git branch -C master should work when master is checked out' '
+       git checkout master &&
+       git branch -C master
+ '
+ test_expect_success 'git branch -C master master should work when master is checked out' '
+       git checkout master &&
+       git branch -C master master
+ '
+ test_expect_success 'git branch -C master5 master5 should work when master is checked out' '
+       git checkout master &&
+       git branch master5 &&
+       git branch -C master5 master5
+ '
+ test_expect_success 'git branch -C ab cd should overwrite existing config for cd' '
+       git branch -l cd &&
+       git reflog exists refs/heads/cd &&
+       git config branch.cd.dummy CD &&
+       git branch -l ab &&
+       git reflog exists refs/heads/ab &&
+       git config branch.ab.dummy AB &&
+       git branch -C ab cd &&
+       git reflog exists refs/heads/ab &&
+       git reflog exists refs/heads/cd &&
+       test $(git config branch.ab.dummy) = AB &&
+       test $(git config branch.cd.dummy) = AB
+ '
+ test_expect_success 'git branch -c correctly copies multiple config sections' '
+       FOO=1 &&
+       export FOO &&
+       test_when_finished "git checkout master" &&
+       git checkout -b source2 master &&
+       # Assert that a config file with multiple config sections has
+       # those sections preserved...
+       cat >expect <<-\EOF &&
+       branch.source2.key1=value1
+       branch.dest2.key1=value1
+       more.gar.b=age
+       branch.source2.key2=value2
+       branch.dest2.key2=value2
+       EOF
+       cat >config.branch <<\EOF &&
+ ;; Note the lack of -\EOF above & mixed indenting here. This is
+ ;; intentional, we are also testing that the formatting of copied
+ ;; sections is preserved.
+ ;; Comment for source2. Tabs
+ [branch "source2"]
+       ;; Comment for the source2 value
+       key1 = value1
+ ;; Comment for more.gar. Spaces
+ [more "gar"]
+     ;; Comment for the more.gar value
+     b = age
+ ;; Comment for source2, again. Mixed tabs/spaces.
+ [branch "source2"]
+     ;; Comment for the source2 value, again
+       key2 = value2
+ EOF
+       cat config.branch >>.git/config &&
+       git branch -c source2 dest2 &&
+       git config -f .git/config -l | grep -F -e source2 -e dest2 -e more.gar >actual &&
+       test_cmp expect actual &&
+       # ...and that the comments and formatting for those sections
+       # is also preserved.
+       cat >expect <<\EOF &&
+ ;; Comment for source2. Tabs
+ [branch "source2"]
+       ;; Comment for the source2 value
+       key1 = value1
+ ;; Comment for more.gar. Spaces
+ [branch "dest2"]
+       ;; Comment for the source2 value
+       key1 = value1
+ ;; Comment for more.gar. Spaces
+ [more "gar"]
+     ;; Comment for the more.gar value
+     b = age
+ ;; Comment for source2, again. Mixed tabs/spaces.
+ [branch "source2"]
+     ;; Comment for the source2 value, again
+       key2 = value2
+ [branch "dest2"]
+     ;; Comment for the source2 value, again
+       key2 = value2
+ EOF
+       sed -n -e "/Comment for source2/,\$p" .git/config >actual &&
+       test_cmp expect actual
+ '
  test_expect_success 'deleting a symref' '
        git branch target &&
        git symbolic-ref refs/heads/symref refs/heads/target &&
@@@ -572,7 -788,6 +828,7 @@@ test_expect_success 'use --set-upstream
  test_expect_success 'use --set-upstream-to modify a particular branch' '
        git branch my13 &&
        git branch --set-upstream-to master my13 &&
 +      test_when_finished "git branch --unset-upstream my13" &&
        test "$(git config branch.my13.remote)" = "." &&
        test "$(git config branch.my13.merge)" = "refs/heads/master"
  '
@@@ -618,8 -833,38 +874,8 @@@ test_expect_success 'test --unset-upstr
        test_must_fail git config branch.my14.merge
  '
  
 -test_expect_success '--set-upstream shows message when creating a new branch that exists as remote-tracking' '
 -      git update-ref refs/remotes/origin/master HEAD &&
 -      git branch --set-upstream origin/master 2>actual &&
 -      test_when_finished git update-ref -d refs/remotes/origin/master &&
 -      test_when_finished git branch -d origin/master &&
 -      cat >expected <<EOF &&
 -The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
 -
 -If you wanted to make '"'master'"' track '"'origin/master'"', do this:
 -
 -    git branch -d origin/master
 -    git branch --set-upstream-to origin/master
 -EOF
 -      test_i18ncmp expected actual
 -'
 -
 -test_expect_success '--set-upstream with two args only shows the deprecation message' '
 -      git branch --set-upstream master my13 2>actual &&
 -      test_when_finished git branch --unset-upstream master &&
 -      cat >expected <<EOF &&
 -The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
 -EOF
 -      test_i18ncmp expected actual
 -'
 -
 -test_expect_success '--set-upstream with one arg only shows the deprecation message if the branch existed' '
 -      git branch --set-upstream my13 2>actual &&
 -      test_when_finished git branch --unset-upstream my13 &&
 -      cat >expected <<EOF &&
 -The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
 -EOF
 -      test_i18ncmp expected actual
 +test_expect_success '--set-upstream fails' '
 +    test_must_fail git branch --set-upstream origin/master
  '
  
  test_expect_success '--set-upstream-to notices an error to set branch as own upstream' '
@@@ -944,6 -1189,19 +1200,6 @@@ test_expect_success 'attempt to delete 
        test_must_fail git branch -d my10
  '
  
 -test_expect_success 'use set-upstream on the current branch' '
 -      git checkout master &&
 -      git --bare init myupstream.git &&
 -      git push myupstream.git master:refs/heads/frotz &&
 -      git remote add origin myupstream.git &&
 -      git fetch &&
 -      git branch --set-upstream master origin/frotz &&
 -
 -      test "z$(git config branch.master.remote)" = "zorigin" &&
 -      test "z$(git config branch.master.merge)" = "zrefs/heads/frotz"
 -
 -'
 -
  test_expect_success 'use --edit-description' '
        write_script editor <<-\EOF &&
                echo "New contents" >"$1"