Merge branch 'ds/commit-graph-lockfile-fix'
authorJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:36 +0000 (13:22 -0700)
committerJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:36 +0000 (13:22 -0700)
Update to ds/generation-numbers topic.

* ds/commit-graph-lockfile-fix:
commit-graph: fix UX issue when .lock file exists
commit-graph.txt: update design document
merge: check config before loading commits
commit: use generation number in remove_redundant()
commit: add short-circuit to paint_down_to_common()
commit: use generation numbers for in_merge_bases()
ref-filter: use generation number for --contains
commit-graph: always load commit-graph information
commit: use generations in paint_down_to_common()
commit-graph: compute generation numbers
commit: add generation number to struct commit
ref-filter: fix outdated comment on in_commit_list

1  2 
builtin/merge.c
commit-graph.c
commit.c
commit.h
object.c
ref-filter.c
sha1-file.c
diff --combined builtin/merge.c
index fb4faca2507fdf00a1bbd48817e2ff0bc9957fc3,b8197569465a05d4c7804a330ff02ea4e721f292..4a4c09496cfee08417c18cc010528464a3137488
@@@ -14,7 -14,6 +14,7 @@@
  #include "run-command.h"
  #include "diff.h"
  #include "refs.h"
 +#include "refspec.h"
  #include "commit.h"
  #include "diffcore.h"
  #include "revision.h"
@@@ -34,8 -33,6 +34,8 @@@
  #include "sequencer.h"
  #include "string-list.h"
  #include "packfile.h"
 +#include "tag.h"
 +#include "alias.h"
  
  #define DEFAULT_TWOHEAD (1<<0)
  #define DEFAULT_OCTOPUS (1<<1)
@@@ -215,9 -212,9 +215,9 @@@ static struct option builtin_merge_opti
        OPT_BOOL('e', "edit", &option_edit,
                N_("edit message before committing")),
        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 -      { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
 -              N_("abort if fast-forward is not possible"),
 -              PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
 +      OPT_SET_INT_F(0, "ff-only", &fast_forward,
 +                    N_("abort if fast-forward is not possible"),
 +                    FF_ONLY, PARSE_OPT_NONEG),
        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
        OPT_BOOL(0, "verify-signatures", &verify_signatures,
                N_("verify that the named commit has a valid GPG signature")),
@@@ -282,7 -279,7 +282,7 @@@ out
        return rc;
  }
  
 -static void read_empty(unsigned const char *sha1, int verbose)
 +static void read_empty(const struct object_id *oid, int verbose)
  {
        int i = 0;
        const char *args[7];
                args[i++] = "-v";
        args[i++] = "-m";
        args[i++] = "-u";
 -      args[i++] = EMPTY_TREE_SHA1_HEX;
 -      args[i++] = sha1_to_hex(sha1);
 +      args[i++] = empty_tree_oid_hex();
 +      args[i++] = oid_to_hex(oid);
        args[i] = NULL;
  
        if (run_command_v_opt(args, RUN_GIT_CMD))
                die(_("read-tree failed"));
  }
  
 -static void reset_hard(unsigned const char *sha1, int verbose)
 +static void reset_hard(const struct object_id *oid, int verbose)
  {
        int i = 0;
        const char *args[6];
                args[i++] = "-v";
        args[i++] = "--reset";
        args[i++] = "-u";
 -      args[i++] = sha1_to_hex(sha1);
 +      args[i++] = oid_to_hex(oid);
        args[i] = NULL;
  
        if (run_command_v_opt(args, RUN_GIT_CMD))
@@@ -326,7 -323,7 +326,7 @@@ static void restore_state(const struct 
        if (is_null_oid(stash))
                return;
  
 -      reset_hard(head->hash, 1);
 +      reset_hard(head, 1);
  
        args[2] = oid_to_hex(stash);
  
@@@ -414,7 -411,7 +414,7 @@@ static void finish(struct commit *head_
                         * We ignore errors in 'gc --auto', since the
                         * user should see them.
                         */
 -                      close_all_packs();
 +                      close_all_packs(the_repository->objects);
                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
                }
        }
@@@ -445,7 -442,6 +445,7 @@@ static void merge_name(const char *remo
        struct object_id branch_head;
        struct strbuf buf = STRBUF_INIT;
        struct strbuf bname = STRBUF_INIT;
 +      struct merge_remote_desc *desc;
        const char *ptr;
        char *found_ref;
        int len, early;
                strbuf_release(&truname);
        }
  
 -      if (remote_head->util) {
 -              struct merge_remote_desc *desc;
 -              desc = merge_remote_util(remote_head);
 -              if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 -                      strbuf_addf(msg, "%s\t\t%s '%s'\n",
 -                                  oid_to_hex(&desc->obj->oid),
 -                                  type_name(desc->obj->type),
 -                                  remote);
 -                      goto cleanup;
 -              }
 +      desc = merge_remote_util(remote_head);
 +      if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 +              strbuf_addf(msg, "%s\t\t%s '%s'\n",
 +                          oid_to_hex(&desc->obj->oid),
 +                          type_name(desc->obj->type),
 +                          remote);
 +              goto cleanup;
        }
  
        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
@@@ -639,7 -638,7 +639,7 @@@ static int read_tree_trivial(struct obj
  
  static void write_tree_trivial(struct object_id *oid)
  {
 -      if (write_cache_as_tree(oid->hash, 0, NULL))
 +      if (write_cache_as_tree(oid, 0, NULL))
                die(_("git write-tree failed to write a tree"));
  }
  
@@@ -647,14 -646,15 +647,14 @@@ static int try_merge_strategy(const cha
                              struct commit_list *remoteheads,
                              struct commit *head)
  {
 -      static struct lock_file lock;
 +      struct lock_file lock = LOCK_INIT;
        const char *head_arg = "HEAD";
  
        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
        refresh_cache(REFRESH_QUIET);
 -      if (active_cache_changed &&
 -          write_locked_index(&the_index, &lock, COMMIT_LOCK))
 +      if (write_locked_index(&the_index, &lock,
 +                             COMMIT_LOCK | SKIP_IF_UNCHANGED))
                return error(_("Unable to write index."));
 -      rollback_lock_file(&lock);
  
        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
                int clean, x;
                                remoteheads->item, reversed, &result);
                if (clean < 0)
                        exit(128);
 -              if (active_cache_changed &&
 -                  write_locked_index(&the_index, &lock, COMMIT_LOCK))
 +              if (write_locked_index(&the_index, &lock,
 +                                     COMMIT_LOCK | SKIP_IF_UNCHANGED))
                        die (_("unable to write %s"), get_index_file());
 -              rollback_lock_file(&lock);
                return clean ? 0 : 1;
        } else {
                return try_merge_command(strategy, xopts_nr, xopts,
@@@ -805,13 -806,14 +805,13 @@@ static int merge_trivial(struct commit 
  {
        struct object_id result_tree, result_commit;
        struct commit_list *parents, **pptr = &parents;
 -      static struct lock_file lock;
 +      struct lock_file lock = LOCK_INIT;
  
        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
        refresh_cache(REFRESH_QUIET);
 -      if (active_cache_changed &&
 -          write_locked_index(&the_index, &lock, COMMIT_LOCK))
 +      if (write_locked_index(&the_index, &lock,
 +                             COMMIT_LOCK | SKIP_IF_UNCHANGED))
                return error(_("Unable to write index."));
 -      rollback_lock_file(&lock);
  
        write_tree_trivial(&result_tree);
        printf(_("Wonderful.\n"));
@@@ -932,11 -934,8 +932,11 @@@ static void write_merge_heads(struct co
        for (j = remoteheads; j; j = j->next) {
                struct object_id *oid;
                struct commit *c = j->item;
 -              if (c->util && merge_remote_util(c)->obj) {
 -                      oid = &merge_remote_util(c)->obj->oid;
 +              struct merge_remote_desc *desc;
 +
 +              desc = merge_remote_util(c);
 +              if (desc && desc->obj) {
 +                      oid = &desc->obj->oid;
                } else {
                        oid = &c->object.oid;
                }
@@@ -1126,43 -1125,6 +1126,43 @@@ static struct commit_list *collect_pare
        return remoteheads;
  }
  
 +static int merging_a_throwaway_tag(struct commit *commit)
 +{
 +      char *tag_ref;
 +      struct object_id oid;
 +      int is_throwaway_tag = 0;
 +
 +      /* Are we merging a tag? */
 +      if (!merge_remote_util(commit) ||
 +          !merge_remote_util(commit)->obj ||
 +          merge_remote_util(commit)->obj->type != OBJ_TAG)
 +              return is_throwaway_tag;
 +
 +      /*
 +       * Now we know we are merging a tag object.  Are we downstream
 +       * and following the tags from upstream?  If so, we must have
 +       * the tag object pointed at by "refs/tags/$T" where $T is the
 +       * tagname recorded in the tag object.  We want to allow such
 +       * a "just to catch up" merge to fast-forward.
 +       *
 +       * Otherwise, we are playing an integrator's role, making a
 +       * merge with a throw-away tag from a contributor with
 +       * something like "git pull $contributor $signed_tag".
 +       * We want to forbid such a merge from fast-forwarding
 +       * by default; otherwise we would not keep the signature
 +       * anywhere.
 +       */
 +      tag_ref = xstrfmt("refs/tags/%s",
 +                        ((struct tag *)merge_remote_util(commit)->obj)->tag);
 +      if (!read_ref(tag_ref, &oid) &&
 +          !oidcmp(&oid, &merge_remote_util(commit)->obj->oid))
 +              is_throwaway_tag = 0;
 +      else
 +              is_throwaway_tag = 1;
 +      free(tag_ref);
 +      return is_throwaway_tag;
 +}
 +
  int cmd_merge(int argc, const char **argv, const char *prefix)
  {
        struct object_id result_tree, stash, head_oid;
        branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
        if (branch)
                skip_prefix(branch, "refs/heads/", &branch);
+       init_diff_ui_defaults();
+       git_config(git_merge_config, NULL);
        if (!branch || is_null_oid(&head_oid))
                head_commit = NULL;
        else
                head_commit = lookup_commit_or_die(&head_oid, "HEAD");
  
-       init_diff_ui_defaults();
-       git_config(git_merge_config, NULL);
        if (branch_mergeoptions)
                parse_branch_merge_options(branch_mergeoptions);
        argc = parse_options(argc, argv, prefix, builtin_merge_options,
                if (remoteheads->next)
                        die(_("Can merge only exactly one commit into empty head"));
                remote_head_oid = &remoteheads->item->object.oid;
 -              read_empty(remote_head_oid->hash, 0);
 +              read_empty(remote_head_oid, 0);
                update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
                           UPDATE_REFS_DIE_ON_ERR);
                goto done;
  
                        check_commit_signature(commit, &signature_check);
  
 -                      find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
 +                      find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
                        switch (signature_check.result) {
                        case 'G':
                                break;
                            oid_to_hex(&commit->object.oid));
                setenv(buf.buf, merge_remote_util(commit)->name, 1);
                strbuf_reset(&buf);
 -              if (fast_forward != FF_ONLY &&
 -                  merge_remote_util(commit) &&
 -                  merge_remote_util(commit)->obj &&
 -                  merge_remote_util(commit)->obj->type == OBJ_TAG)
 +              if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
                        fast_forward = FF_NO;
        }
  
  
                if (verbosity >= 0) {
                        printf(_("Updating %s..%s\n"),
 -                             find_unique_abbrev(head_commit->object.oid.hash,
 +                             find_unique_abbrev(&head_commit->object.oid,
                                                  DEFAULT_ABBREV),
 -                             find_unique_abbrev(remoteheads->item->object.oid.hash,
 +                             find_unique_abbrev(&remoteheads->item->object.oid,
                                                  DEFAULT_ABBREV));
                }
                strbuf_addstr(&msg, "Fast-forward");
diff --combined commit-graph.c
index 4c6127088ff96282fbcdc98ef5767281e52846e9,bb54c1214c84c66b173d236b2851a47a517dab30..b63a1fc85eaded844fcb1a2634067f9509b5937c
@@@ -1,5 -1,6 +1,6 @@@
  #include "cache.h"
  #include "config.h"
+ #include "dir.h"
  #include "git-compat-util.h"
  #include "lockfile.h"
  #include "pack.h"
@@@ -9,7 -10,6 +10,7 @@@
  #include "revision.h"
  #include "sha1-lookup.h"
  #include "commit-graph.h"
 +#include "object-store.h"
  
  #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
@@@ -207,10 -207,8 +208,10 @@@ static void prepare_commit_graph(void
  
        obj_dir = get_object_directory();
        prepare_commit_graph_one(obj_dir);
 -      prepare_alt_odb();
 -      for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
 +      prepare_alt_odb(the_repository);
 +      for (alt = the_repository->objects->alt_odb_list;
 +           !commit_graph && alt;
 +           alt = alt->next)
                prepare_commit_graph_one(alt->path);
  }
  
@@@ -248,6 -246,13 +249,13 @@@ static struct commit_list **insert_pare
        return &commit_list_insert(c, pptr)->next;
  }
  
+ static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
+ {
+       const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
+       item->graph_pos = pos;
+       item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
+ }
  static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
  {
        uint32_t edge_value;
        date_low = get_be32(commit_data + g->hash_len + 12);
        item->date = (timestamp_t)((date_high << 32) | date_low);
  
+       item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
        pptr = &item->parents;
  
        edge_value = get_be32(commit_data + g->hash_len);
        return 1;
  }
  
+ static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
+ {
+       if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
+               *pos = item->graph_pos;
+               return 1;
+       } else {
+               return bsearch_graph(g, &(item->object.oid), pos);
+       }
+ }
  int parse_commit_in_graph(struct commit *item)
  {
+       uint32_t pos;
        if (!core_commit_graph)
                return 0;
        if (item->object.parsed)
                return 1;
        prepare_commit_graph();
-       if (commit_graph) {
-               uint32_t pos;
-               int found;
-               if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
-                       pos = item->graph_pos;
-                       found = 1;
-               } else {
-                       found = bsearch_graph(commit_graph, &(item->object.oid), &pos);
-               }
-               if (found)
-                       return fill_commit_in_graph(item, commit_graph, pos);
-       }
+       if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
+               return fill_commit_in_graph(item, commit_graph, pos);
        return 0;
  }
  
+ void load_commit_graph_info(struct commit *item)
+ {
+       uint32_t pos;
+       if (!core_commit_graph)
+               return;
+       prepare_commit_graph();
+       if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
+               fill_commit_graph_info(item, commit_graph, pos);
+ }
  static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
  {
        struct object_id oid;
@@@ -440,6 -456,8 +459,8 @@@ static void write_graph_chunk_data(stru
                else
                        packedDate[0] = 0;
  
+               packedDate[0] |= htonl((*list)->generation << 2);
                packedDate[1] = htonl((*list)->date);
                hashwrite(f, packedDate, 8);
  
@@@ -515,7 -533,7 +536,7 @@@ static int add_packed_commits(const str
        struct object_info oi = OBJECT_INFO_INIT;
  
        oi.typep = &type;
 -      if (packed_object_info(pack, offset, &oi) < 0)
 +      if (packed_object_info(the_repository, pack, offset, &oi) < 0)
                die("unable to get type of object %s", oid_to_hex(oid));
  
        if (type != OBJ_COMMIT)
@@@ -572,6 -590,45 +593,45 @@@ static void close_reachable(struct pack
        }
  }
  
+ static void compute_generation_numbers(struct packed_commit_list* commits)
+ {
+       int i;
+       struct commit_list *list = NULL;
+       for (i = 0; i < commits->nr; i++) {
+               if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
+                   commits->list[i]->generation != GENERATION_NUMBER_ZERO)
+                       continue;
+               commit_list_insert(commits->list[i], &list);
+               while (list) {
+                       struct commit *current = list->item;
+                       struct commit_list *parent;
+                       int all_parents_computed = 1;
+                       uint32_t max_generation = 0;
+                       for (parent = current->parents; parent; parent = parent->next) {
+                               if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
+                                   parent->item->generation == GENERATION_NUMBER_ZERO) {
+                                       all_parents_computed = 0;
+                                       commit_list_insert(parent->item, &list);
+                                       break;
+                               } else if (parent->item->generation > max_generation) {
+                                       max_generation = parent->item->generation;
+                               }
+                       }
+                       if (all_parents_computed) {
+                               current->generation = max_generation + 1;
+                               pop_commit(&list);
+                               if (current->generation > GENERATION_NUMBER_MAX)
+                                       current->generation = GENERATION_NUMBER_MAX;
+                       }
+               }
+       }
+ }
  void write_commit_graph(const char *obj_dir,
                        const char **pack_indexes,
                        int nr_packs,
        struct hashfile *f;
        uint32_t i, count_distinct = 0;
        char *graph_name;
-       int fd;
        struct lock_file lk = LOCK_INIT;
        uint32_t chunk_ids[5];
        uint64_t chunk_offsets[5];
        if (commits.nr >= GRAPH_PARENT_MISSING)
                die(_("too many commits to write graph"));
  
-       graph_name = get_commit_graph_filename(obj_dir);
-       fd = hold_lock_file_for_update(&lk, graph_name, 0);
-       if (fd < 0) {
-               struct strbuf folder = STRBUF_INIT;
-               strbuf_addstr(&folder, graph_name);
-               strbuf_setlen(&folder, strrchr(folder.buf, '/') - folder.buf);
-               if (mkdir(folder.buf, 0777) < 0)
-                       die_errno(_("cannot mkdir %s"), folder.buf);
-               strbuf_release(&folder);
-               fd = hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
+       compute_generation_numbers(&commits);
  
-               if (fd < 0)
-                       die_errno("unable to create '%s'", graph_name);
-       }
+       graph_name = get_commit_graph_filename(obj_dir);
+       if (safe_create_leading_directories(graph_name))
+               die_errno(_("unable to create leading directories of %s"),
+                         graph_name);
  
+       hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
        f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
  
        hashwrite_be32(f, GRAPH_SIGNATURE);
diff --combined commit.c
index 2d4431a21fd16f55d873b6fe2ba1126722d3c4bf,1d28677dfb701824f1afb4c51e673d57606c2d4e..298ad747c6e0d8b1e800b5e643ab0fa6f67cd491
+++ b/commit.c
@@@ -13,7 -13,6 +13,7 @@@
  #include "prio-queue.h"
  #include "sha1-lookup.h"
  #include "wt-status.h"
 +#include "advice.h"
  
  static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  
@@@ -178,15 -177,6 +178,15 @@@ static int read_graft_file(const char *
        struct strbuf buf = STRBUF_INIT;
        if (!fp)
                return -1;
 +      if (advice_graft_file_deprecated)
 +              advise(_("Support for <GIT_DIR>/info/grafts is deprecated\n"
 +                       "and will be removed in a future Git version.\n"
 +                       "\n"
 +                       "Please use \"git replace --convert-graft-file\"\n"
 +                       "to convert the grafts into replace refs.\n"
 +                       "\n"
 +                       "Turn this message off by running\n"
 +                       "\"git config advice.graftFileDeprecated false\""));
        while (!strbuf_getwholeline(&buf, fp, '\n')) {
                /* The format is just "Commit Parent1 Parent2 ...\n" */
                struct commit_graft *graft = read_graft_line(&buf);
@@@ -207,9 -197,6 +207,9 @@@ static void prepare_commit_graft(void
  
        if (commit_graft_prepared)
                return;
 +      if (!startup_info->have_repository)
 +              return;
 +
        graft_file = get_graft_file();
        read_graft_file(graft_file);
        /* make sure shallows are read */
@@@ -280,7 -267,7 +280,7 @@@ const void *get_commit_buffer(const str
        if (!ret) {
                enum object_type type;
                unsigned long size;
 -              ret = read_sha1_file(commit->object.oid.hash, &type, &size);
 +              ret = read_object_file(&commit->object.oid, &type, &size);
                if (!ret)
                        die("cannot read commit object %s",
                            oid_to_hex(&commit->object.oid));
@@@ -344,7 -331,7 +344,7 @@@ const void *detach_commit_buffer(struc
        return ret;
  }
  
- int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
+ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph)
  {
        const char *tail = buffer;
        const char *bufptr = buffer;
        if (tail <= bufptr + tree_entry_len + 1 || memcmp(bufptr, "tree ", 5) ||
                        bufptr[tree_entry_len] != '\n')
                return error("bogus commit object %s", oid_to_hex(&item->object.oid));
 -      if (get_sha1_hex(bufptr + 5, parent.hash) < 0)
 +      if (get_oid_hex(bufptr + 5, &parent) < 0)
                return error("bad tree pointer in commit %s",
                             oid_to_hex(&item->object.oid));
        item->maybe_tree = lookup_tree(&parent);
                struct commit *new_parent;
  
                if (tail <= bufptr + parent_entry_len + 1 ||
 -                  get_sha1_hex(bufptr + 7, parent.hash) ||
 +                  get_oid_hex(bufptr + 7, &parent) ||
                    bufptr[parent_entry_len] != '\n')
                        return error("bad parents in commit %s", oid_to_hex(&item->object.oid));
                bufptr += parent_entry_len + 1;
        }
        item->date = parse_commit_date(bufptr, tail);
  
+       if (check_graph)
+               load_commit_graph_info(item);
        return 0;
  }
  
@@@ -415,7 -405,7 +418,7 @@@ int parse_commit_gently(struct commit *
                return 0;
        if (parse_commit_in_graph(item))
                return 0;
 -      buffer = read_sha1_file(item->object.oid.hash, &type, &size);
 +      buffer = read_object_file(&item->object.oid, &type, &size);
        if (!buffer)
                return quiet_on_missing ? -1 :
                        error("Could not read %s",
                return error("Object %s not a commit",
                             oid_to_hex(&item->object.oid));
        }
-       ret = parse_commit_buffer(item, buffer, size);
+       ret = parse_commit_buffer(item, buffer, size, 0);
        if (save_commit_buffer && !ret) {
                set_commit_buffer(item, buffer, size);
                return 0;
@@@ -653,6 -643,24 +656,24 @@@ static int compare_commits_by_author_da
        return 0;
  }
  
+ int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused)
+ {
+       const struct commit *a = a_, *b = b_;
+       /* newer commits first */
+       if (a->generation < b->generation)
+               return 1;
+       else if (a->generation > b->generation)
+               return -1;
+       /* use date as a heuristic when generations are equal */
+       if (a->date < b->date)
+               return 1;
+       else if (a->date > b->date)
+               return -1;
+       return 0;
+ }
  int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
  {
        const struct commit *a = a_, *b = b_;
@@@ -800,11 -808,14 +821,14 @@@ static int queue_has_nonstale(struct pr
  }
  
  /* all input commits in one and twos[] must have been parsed! */
- static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
+ static struct commit_list *paint_down_to_common(struct commit *one, int n,
+                                               struct commit **twos,
+                                               int min_generation)
  {
-       struct prio_queue queue = { compare_commits_by_commit_date };
+       struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
        struct commit_list *result = NULL;
        int i;
+       uint32_t last_gen = GENERATION_NUMBER_INFINITY;
  
        one->object.flags |= PARENT1;
        if (!n) {
                struct commit_list *parents;
                int flags;
  
+               if (commit->generation > last_gen)
+                       BUG("bad generation skip %8x > %8x at %s",
+                           commit->generation, last_gen,
+                           oid_to_hex(&commit->object.oid));
+               last_gen = commit->generation;
+               if (commit->generation < min_generation)
+                       break;
                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
                if (flags == (PARENT1 | PARENT2)) {
                        if (!(commit->object.flags & RESULT)) {
@@@ -871,7 -891,7 +904,7 @@@ static struct commit_list *merge_bases_
                        return NULL;
        }
  
-       list = paint_down_to_common(one, n, twos);
+       list = paint_down_to_common(one, n, twos, 0);
  
        while (list) {
                struct commit *commit = pop_commit(&list);
@@@ -929,6 -949,7 +962,7 @@@ static int remove_redundant(struct comm
                parse_commit(array[i]);
        for (i = 0; i < cnt; i++) {
                struct commit_list *common;
+               uint32_t min_generation = array[i]->generation;
  
                if (redundant[i])
                        continue;
                                continue;
                        filled_index[filled] = j;
                        work[filled++] = array[j];
+                       if (array[j]->generation < min_generation)
+                               min_generation = array[j]->generation;
                }
-               common = paint_down_to_common(array[i], filled, work);
+               common = paint_down_to_common(array[i], filled, work,
+                                             min_generation);
                if (array[i]->object.flags & PARENT2)
                        redundant[i] = 1;
                for (j = 0; j < filled; j++)
@@@ -1048,14 -1073,21 +1086,21 @@@ int in_merge_bases_many(struct commit *
  {
        struct commit_list *bases;
        int ret = 0, i;
+       uint32_t min_generation = GENERATION_NUMBER_INFINITY;
  
        if (parse_commit(commit))
                return ret;
-       for (i = 0; i < nr_reference; i++)
+       for (i = 0; i < nr_reference; i++) {
                if (parse_commit(reference[i]))
                        return ret;
+               if (reference[i]->generation < min_generation)
+                       min_generation = reference[i]->generation;
+       }
+       if (commit->generation > min_generation)
+               return ret;
  
-       bases = paint_down_to_common(commit, nr_reference, reference);
+       bases = paint_down_to_common(commit, nr_reference, reference, commit->generation);
        if (commit->object.flags & PARENT2)
                ret = 1;
        clear_commit_marks(commit, all_flags);
@@@ -1238,7 -1270,7 +1283,7 @@@ static void handle_signed_tag(struct co
        desc = merge_remote_util(parent);
        if (!desc || !desc->obj)
                return;
 -      buf = read_sha1_file(desc->obj->oid.hash, &type, &size);
 +      buf = read_object_file(&desc->obj->oid, &type, &size);
        if (!buf || type != OBJ_TAG)
                goto free_return;
        len = parse_signature(buf, size);
@@@ -1320,19 -1352,17 +1365,19 @@@ struct commit_extra_header *read_commit
        return extra;
  }
  
 -void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
 +int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
  {
        struct commit_extra_header *extra, *to_free;
 +      int res = 0;
  
        to_free = read_commit_extra_headers(commit, NULL);
 -      for (extra = to_free; extra; extra = extra->next) {
 +      for (extra = to_free; !res && extra; extra = extra->next) {
                if (strcmp(extra->key, "mergetag"))
                        continue; /* not a merge tag */
 -              fn(commit, extra, data);
 +              res = fn(commit, extra, data);
        }
        free_commit_extra_headers(to_free);
 +      return res;
  }
  
  static inline int standard_header_field(const char *field, size_t len)
@@@ -1551,7 -1581,7 +1596,7 @@@ int commit_tree_extended(const char *ms
        int encoding_is_utf8;
        struct strbuf buffer;
  
 -      assert_sha1_type(tree->hash, OBJ_TREE);
 +      assert_oid_type(tree, OBJ_TREE);
  
        if (memchr(msg, '\0', msg_len))
                return error("a NUL byte in commit log message not allowed.");
        return result;
  }
  
 +define_commit_slab(merge_desc_slab, struct merge_remote_desc *);
 +static struct merge_desc_slab merge_desc_slab = COMMIT_SLAB_INIT(1, merge_desc_slab);
 +
 +struct merge_remote_desc *merge_remote_util(struct commit *commit)
 +{
 +      return *merge_desc_slab_at(&merge_desc_slab, commit);
 +}
 +
  void set_merge_remote_desc(struct commit *commit,
                           const char *name, struct object *obj)
  {
        struct merge_remote_desc *desc;
        FLEX_ALLOC_STR(desc, name, name);
        desc->obj = obj;
 -      commit->util = desc;
 +      *merge_desc_slab_at(&merge_desc_slab, commit) = desc;
  }
  
  struct commit *get_merge_parent(const char *name)
                return NULL;
        obj = parse_object(&oid);
        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 -      if (commit && !commit->util)
 +      if (commit && !merge_remote_util(commit))
                set_merge_remote_desc(commit, name, obj);
        return commit;
  }
diff --combined commit.h
index e48f05dffcac2fc780386626701cdc64bd795076,b5afde1ae901d3b90643d8e84a3fbfe997f2ba65..cb943013d06a58f2e0427a33f5ab718df23e730f
+++ b/commit.h
  #include "pretty.h"
  
  #define COMMIT_NOT_FROM_GRAPH 0xFFFFFFFF
+ #define GENERATION_NUMBER_INFINITY 0xFFFFFFFF
+ #define GENERATION_NUMBER_MAX 0x3FFFFFFF
+ #define GENERATION_NUMBER_ZERO 0
  
  struct commit_list {
        struct commit *item;
        struct commit_list *next;
  };
  
 +/*
 + * The size of this struct matters in full repo walk operations like
 + * 'git clone' or 'git gc'. Consider using commit-slab to attach data
 + * to a commit instead of adding new fields here.
 + */
  struct commit {
        struct object object;
 -      void *util;
 -      unsigned int index;
        timestamp_t date;
        struct commit_list *parents;
  
@@@ -33,7 -33,7 +36,8 @@@
         */
        struct tree *maybe_tree;
        uint32_t graph_pos;
+       uint32_t generation;
 +      unsigned int index;
  };
  
  extern int save_commit_buffer;
@@@ -72,7 -72,7 +76,7 @@@ struct commit *lookup_commit_reference_
   */
  struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref_name);
  
- int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size);
+ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph);
  int parse_commit_gently(struct commit *item, int quiet_on_missing);
  static inline int parse_commit(struct commit *item)
  {
@@@ -307,16 -307,16 +311,16 @@@ extern const char *find_commit_header(c
  /* Find the end of the log message, the right place for a new trailer. */
  extern int ignore_non_trailer(const char *buf, size_t len);
  
 -typedef void (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
 +typedef int (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
                                 void *cb_data);
  
 -extern void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
 +extern int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
  
  struct merge_remote_desc {
        struct object *obj; /* the named object, could be a tag */
        char name[FLEX_ARRAY];
  };
 -#define merge_remote_util(commit) ((struct merge_remote_desc *)((commit)->util))
 +extern struct merge_remote_desc *merge_remote_util(struct commit *);
  extern void set_merge_remote_desc(struct commit *commit,
                                  const char *name, struct object *obj);
  
@@@ -341,6 -341,7 +345,7 @@@ extern int remove_signature(struct strb
  extern int check_commit_signature(const struct commit *commit, struct signature_check *sigc);
  
  int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
+ int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused);
  
  LAST_ARG_MUST_BE_NULL
  extern int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...);
diff --combined object.c
index f7f4de3aaf6d42a6dde5811b37aa8239ac183754,efe48713252a779c6e7425e8a40481d5881f7902..d33e2a5cc84623451a0cc02c0345233675b0340d
+++ b/object.c
@@@ -1,12 -1,9 +1,12 @@@
  #include "cache.h"
  #include "object.h"
 +#include "replace-object.h"
  #include "blob.h"
  #include "tree.h"
  #include "commit.h"
  #include "tag.h"
 +#include "object-store.h"
 +#include "packfile.h"
  
  static struct object **obj_hash;
  static int nr_objs, obj_hash_size;
@@@ -210,7 -207,7 +210,7 @@@ struct object *parse_object_buffer(cons
        } else if (type == OBJ_COMMIT) {
                struct commit *commit = lookup_commit(oid);
                if (commit) {
-                       if (parse_commit_buffer(commit, buffer, size))
+                       if (parse_commit_buffer(commit, buffer, size, 1))
                                return NULL;
                        if (!get_cached_commit_buffer(commit, NULL)) {
                                set_commit_buffer(commit, buffer, size);
@@@ -247,7 -244,7 +247,7 @@@ struct object *parse_object(const struc
        unsigned long size;
        enum object_type type;
        int eaten;
 -      const unsigned char *repl = lookup_replace_object(oid->hash);
 +      const struct object_id *repl = lookup_replace_object(the_repository, oid);
        void *buffer;
        struct object *obj;
  
  
        if ((obj && obj->type == OBJ_BLOB && has_object_file(oid)) ||
            (!obj && has_object_file(oid) &&
 -           sha1_object_info(oid->hash, NULL) == OBJ_BLOB)) {
 -              if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
 +           oid_object_info(the_repository, oid, NULL) == OBJ_BLOB)) {
 +              if (check_object_signature(repl, NULL, 0, NULL) < 0) {
                        error("sha1 mismatch %s", oid_to_hex(oid));
                        return NULL;
                }
                return lookup_object(oid->hash);
        }
  
 -      buffer = read_sha1_file(oid->hash, &type, &size);
 +      buffer = read_object_file(oid, &type, &size);
        if (buffer) {
 -              if (check_sha1_signature(repl, buffer, size, type_name(type)) < 0) {
 +              if (check_object_signature(repl, buffer, size, type_name(type)) < 0) {
                        free(buffer);
 -                      error("sha1 mismatch %s", sha1_to_hex(repl));
 +                      error("sha1 mismatch %s", oid_to_hex(repl));
                        return NULL;
                }
  
@@@ -448,46 -445,3 +448,46 @@@ void clear_commit_marks_all(unsigned in
                        obj->flags &= ~flags;
        }
  }
 +
 +struct raw_object_store *raw_object_store_new(void)
 +{
 +      struct raw_object_store *o = xmalloc(sizeof(*o));
 +
 +      memset(o, 0, sizeof(*o));
 +      INIT_LIST_HEAD(&o->packed_git_mru);
 +      return o;
 +}
 +
 +static void free_alt_odb(struct alternate_object_database *alt)
 +{
 +      strbuf_release(&alt->scratch);
 +      oid_array_clear(&alt->loose_objects_cache);
 +      free(alt);
 +}
 +
 +static void free_alt_odbs(struct raw_object_store *o)
 +{
 +      while (o->alt_odb_list) {
 +              struct alternate_object_database *next;
 +
 +              next = o->alt_odb_list->next;
 +              free_alt_odb(o->alt_odb_list);
 +              o->alt_odb_list = next;
 +      }
 +}
 +
 +void raw_object_store_clear(struct raw_object_store *o)
 +{
 +      FREE_AND_NULL(o->objectdir);
 +      FREE_AND_NULL(o->alternate_db);
 +
 +      oidmap_free(o->replace_map, 1);
 +      FREE_AND_NULL(o->replace_map);
 +
 +      free_alt_odbs(o);
 +      o->alt_odb_tail = NULL;
 +
 +      INIT_LIST_HEAD(&o->packed_git_mru);
 +      close_all_packs(o);
 +      o->packed_git = NULL;
 +}
diff --combined ref-filter.c
index 01c1a82075eca737c2e3749e295ca24bbab870b6,fb35067fc998b040e3fe7f55d3f9051ea1c6a794..fa3685d91f0464a28ef13102a1672215d4ec5177
@@@ -16,6 -16,7 +16,7 @@@
  #include "trailer.h"
  #include "wt-status.h"
  #include "commit-slab.h"
+ #include "commit-graph.h"
  
  static struct ref_msg {
        const char *gone;
@@@ -101,38 -102,22 +102,38 @@@ static struct used_atom 
  } *used_atom;
  static int used_atom_cnt, need_tagged, need_symref;
  
 -static void color_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *color_value)
 +/*
 + * Expand string, append it to strbuf *sb, then return error code ret.
 + * Allow to save few lines of code.
 + */
 +static int strbuf_addf_ret(struct strbuf *sb, int ret, const char *fmt, ...)
 +{
 +      va_list ap;
 +      va_start(ap, fmt);
 +      strbuf_vaddf(sb, fmt, ap);
 +      va_end(ap);
 +      return ret;
 +}
 +
 +static int color_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                           const char *color_value, struct strbuf *err)
  {
        if (!color_value)
 -              die(_("expected format: %%(color:<color>)"));
 +              return strbuf_addf_ret(err, -1, _("expected format: %%(color:<color>)"));
        if (color_parse(color_value, atom->u.color) < 0)
 -              die(_("unrecognized color: %%(color:%s)"), color_value);
 +              return strbuf_addf_ret(err, -1, _("unrecognized color: %%(color:%s)"),
 +                                     color_value);
        /*
         * We check this after we've parsed the color, which lets us complain
         * about syntactically bogus color names even if they won't be used.
         */
        if (!want_color(format->use_color))
                color_parse("", atom->u.color);
 +      return 0;
  }
  
 -static void refname_atom_parser_internal(struct refname_atom *atom,
 -                                       const char *arg, const char *name)
 +static int refname_atom_parser_internal(struct refname_atom *atom, const char *arg,
 +                                       const char *name, struct strbuf *err)
  {
        if (!arg)
                atom->option = R_NORMAL;
                 skip_prefix(arg, "strip=", &arg)) {
                atom->option = R_LSTRIP;
                if (strtol_i(arg, 10, &atom->lstrip))
 -                      die(_("Integer value expected refname:lstrip=%s"), arg);
 +                      return strbuf_addf_ret(err, -1, _("Integer value expected refname:lstrip=%s"), arg);
        } else if (skip_prefix(arg, "rstrip=", &arg)) {
                atom->option = R_RSTRIP;
                if (strtol_i(arg, 10, &atom->rstrip))
 -                      die(_("Integer value expected refname:rstrip=%s"), arg);
 +                      return strbuf_addf_ret(err, -1, _("Integer value expected refname:rstrip=%s"), arg);
        } else
 -              die(_("unrecognized %%(%s) argument: %s"), name, arg);
 +              return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), name, arg);
 +      return 0;
  }
  
 -static void remote_ref_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int remote_ref_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                                const char *arg, struct strbuf *err)
  {
        struct string_list params = STRING_LIST_INIT_DUP;
        int i;
  
        if (!arg) {
                atom->u.remote_ref.option = RR_REF;
 -              refname_atom_parser_internal(&atom->u.remote_ref.refname,
 -                                           arg, atom->name);
 -              return;
 +              return refname_atom_parser_internal(&atom->u.remote_ref.refname,
 +                                                  arg, atom->name, err);
        }
  
        atom->u.remote_ref.nobracket = 0;
                        atom->u.remote_ref.push_remote = 1;
                } else {
                        atom->u.remote_ref.option = RR_REF;
 -                      refname_atom_parser_internal(&atom->u.remote_ref.refname,
 -                                                   arg, atom->name);
 +                      if (refname_atom_parser_internal(&atom->u.remote_ref.refname,
 +                                                       arg, atom->name, err)) {
 +                              string_list_clear(&params, 0);
 +                              return -1;
 +                      }
                }
        }
  
        string_list_clear(&params, 0);
 +      return 0;
  }
  
 -static void body_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int body_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                          const char *arg, struct strbuf *err)
  {
        if (arg)
 -              die(_("%%(body) does not take arguments"));
 +              return strbuf_addf_ret(err, -1, _("%%(body) does not take arguments"));
        atom->u.contents.option = C_BODY_DEP;
 +      return 0;
  }
  
 -static void subject_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int subject_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                             const char *arg, struct strbuf *err)
  {
        if (arg)
 -              die(_("%%(subject) does not take arguments"));
 +              return strbuf_addf_ret(err, -1, _("%%(subject) does not take arguments"));
        atom->u.contents.option = C_SUB;
 +      return 0;
  }
  
 -static void trailers_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int trailers_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                              const char *arg, struct strbuf *err)
  {
        struct string_list params = STRING_LIST_INIT_DUP;
        int i;
                                atom->u.contents.trailer_opts.unfold = 1;
                        else if (!strcmp(s, "only"))
                                atom->u.contents.trailer_opts.only_trailers = 1;
 -                      else
 -                              die(_("unknown %%(trailers) argument: %s"), s);
 +                      else {
 +                              strbuf_addf(err, _("unknown %%(trailers) argument: %s"), s);
 +                              string_list_clear(&params, 0);
 +                              return -1;
 +                      }
                }
        }
        atom->u.contents.option = C_TRAILERS;
        string_list_clear(&params, 0);
 +      return 0;
  }
  
 -static void contents_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int contents_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                              const char *arg, struct strbuf *err)
  {
        if (!arg)
                atom->u.contents.option = C_BARE;
                atom->u.contents.option = C_SUB;
        else if (skip_prefix(arg, "trailers", &arg)) {
                skip_prefix(arg, ":", &arg);
 -              trailers_atom_parser(format, atom, *arg ? arg : NULL);
 +              if (trailers_atom_parser(format, atom, *arg ? arg : NULL, err))
 +                      return -1;
        } else if (skip_prefix(arg, "lines=", &arg)) {
                atom->u.contents.option = C_LINES;
                if (strtoul_ui(arg, 10, &atom->u.contents.nlines))
 -                      die(_("positive value expected contents:lines=%s"), arg);
 +                      return strbuf_addf_ret(err, -1, _("positive value expected contents:lines=%s"), arg);
        } else
 -              die(_("unrecognized %%(contents) argument: %s"), arg);
 +              return strbuf_addf_ret(err, -1, _("unrecognized %%(contents) argument: %s"), arg);
 +      return 0;
  }
  
 -static void objectname_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int objectname_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                                const char *arg, struct strbuf *err)
  {
        if (!arg)
                atom->u.objectname.option = O_FULL;
                atom->u.objectname.option = O_LENGTH;
                if (strtoul_ui(arg, 10, &atom->u.objectname.length) ||
                    atom->u.objectname.length == 0)
 -                      die(_("positive value expected objectname:short=%s"), arg);
 +                      return strbuf_addf_ret(err, -1, _("positive value expected objectname:short=%s"), arg);
                if (atom->u.objectname.length < MINIMUM_ABBREV)
                        atom->u.objectname.length = MINIMUM_ABBREV;
        } else
 -              die(_("unrecognized %%(objectname) argument: %s"), arg);
 +              return strbuf_addf_ret(err, -1, _("unrecognized %%(objectname) argument: %s"), arg);
 +      return 0;
  }
  
 -static void refname_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int refname_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                             const char *arg, struct strbuf *err)
  {
 -      refname_atom_parser_internal(&atom->u.refname, arg, atom->name);
 +      return refname_atom_parser_internal(&atom->u.refname, arg, atom->name, err);
  }
  
  static align_type parse_align_position(const char *s)
        return -1;
  }
  
 -static void align_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int align_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                           const char *arg, struct strbuf *err)
  {
        struct align *align = &atom->u.align;
        struct string_list params = STRING_LIST_INIT_DUP;
        unsigned int width = ~0U;
  
        if (!arg)
 -              die(_("expected format: %%(align:<width>,<position>)"));
 +              return strbuf_addf_ret(err, -1, _("expected format: %%(align:<width>,<position>)"));
  
        align->position = ALIGN_LEFT;
  
  
                if (skip_prefix(s, "position=", &s)) {
                        position = parse_align_position(s);
 -                      if (position < 0)
 -                              die(_("unrecognized position:%s"), s);
 +                      if (position < 0) {
 +                              strbuf_addf(err, _("unrecognized position:%s"), s);
 +                              string_list_clear(&params, 0);
 +                              return -1;
 +                      }
                        align->position = position;
                } else if (skip_prefix(s, "width=", &s)) {
 -                      if (strtoul_ui(s, 10, &width))
 -                              die(_("unrecognized width:%s"), s);
 +                      if (strtoul_ui(s, 10, &width)) {
 +                              strbuf_addf(err, _("unrecognized width:%s"), s);
 +                              string_list_clear(&params, 0);
 +                              return -1;
 +                      }
                } else if (!strtoul_ui(s, 10, &width))
                        ;
                else if ((position = parse_align_position(s)) >= 0)
                        align->position = position;
 -              else
 -                      die(_("unrecognized %%(align) argument: %s"), s);
 +              else {
 +                      strbuf_addf(err, _("unrecognized %%(align) argument: %s"), s);
 +                      string_list_clear(&params, 0);
 +                      return -1;
 +              }
        }
  
 -      if (width == ~0U)
 -              die(_("positive width expected with the %%(align) atom"));
 +      if (width == ~0U) {
 +              string_list_clear(&params, 0);
 +              return strbuf_addf_ret(err, -1, _("positive width expected with the %%(align) atom"));
 +      }
        align->width = width;
        string_list_clear(&params, 0);
 +      return 0;
  }
  
 -static void if_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int if_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                        const char *arg, struct strbuf *err)
  {
        if (!arg) {
                atom->u.if_then_else.cmp_status = COMPARE_NONE;
 -              return;
 +              return 0;
        } else if (skip_prefix(arg, "equals=", &atom->u.if_then_else.str)) {
                atom->u.if_then_else.cmp_status = COMPARE_EQUAL;
        } else if (skip_prefix(arg, "notequals=", &atom->u.if_then_else.str)) {
                atom->u.if_then_else.cmp_status = COMPARE_UNEQUAL;
 -      } else {
 -              die(_("unrecognized %%(if) argument: %s"), arg);
 -      }
 +      } else
 +              return strbuf_addf_ret(err, -1, _("unrecognized %%(if) argument: %s"), arg);
 +      return 0;
  }
  
 -static void head_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 +static int head_atom_parser(const struct ref_format *format, struct used_atom *atom,
 +                          const char *arg, struct strbuf *unused_err)
  {
        atom->u.head = resolve_refdup("HEAD", RESOLVE_REF_READING, NULL, NULL);
 +      return 0;
  }
  
  static struct {
        const char *name;
        cmp_type cmp_type;
 -      void (*parser)(const struct ref_format *format, struct used_atom *atom, const char *arg);
 +      int (*parser)(const struct ref_format *format, struct used_atom *atom,
 +                    const char *arg, struct strbuf *err);
  } valid_atom[] = {
        { "refname" , FIELD_STR, refname_atom_parser },
        { "objecttype" },
@@@ -440,8 -388,7 +441,8 @@@ struct ref_formatting_state 
  
  struct atom_value {
        const char *s;
 -      void (*handler)(struct atom_value *atomv, struct ref_formatting_state *state);
 +      int (*handler)(struct atom_value *atomv, struct ref_formatting_state *state,
 +                     struct strbuf *err);
        uintmax_t value; /* used for sorting when not FIELD_STR */
        struct used_atom *atom;
  };
   * Used to parse format string and sort specifiers
   */
  static int parse_ref_filter_atom(const struct ref_format *format,
 -                               const char *atom, const char *ep)
 +                               const char *atom, const char *ep,
 +                               struct strbuf *err)
  {
        const char *sp;
        const char *arg;
        if (*sp == '*' && sp < ep)
                sp++; /* deref */
        if (ep <= sp)
 -              die(_("malformed field name: %.*s"), (int)(ep-atom), atom);
 +              return strbuf_addf_ret(err, -1, _("malformed field name: %.*s"),
 +                                     (int)(ep-atom), atom);
  
        /* Do we have the atom already used elsewhere? */
        for (i = 0; i < used_atom_cnt; i++) {
        }
  
        if (ARRAY_SIZE(valid_atom) <= i)
 -              die(_("unknown field name: %.*s"), (int)(ep-atom), atom);
 +              return strbuf_addf_ret(err, -1, _("unknown field name: %.*s"),
 +                                     (int)(ep-atom), atom);
  
        /* Add it in, including the deref prefix */
        at = used_atom_cnt;
                }
        }
        memset(&used_atom[at].u, 0, sizeof(used_atom[at].u));
 -      if (valid_atom[i].parser)
 -              valid_atom[i].parser(format, &used_atom[at], arg);
 +      if (valid_atom[i].parser && valid_atom[i].parser(format, &used_atom[at], arg, err))
 +              return -1;
        if (*atom == '*')
                need_tagged = 1;
        if (!strcmp(valid_atom[i].name, "symref"))
@@@ -538,8 -482,7 +539,8 @@@ static void quote_formatting(struct str
        }
  }
  
 -static void append_atom(struct atom_value *v, struct ref_formatting_state *state)
 +static int append_atom(struct atom_value *v, struct ref_formatting_state *state,
 +                     struct strbuf *unused_err)
  {
        /*
         * Quote formatting is only done when the stack has a single
                quote_formatting(&state->stack->output, v->s, state->quote_style);
        else
                strbuf_addstr(&state->stack->output, v->s);
 +      return 0;
  }
  
  static void push_stack_element(struct ref_formatting_stack **stack)
@@@ -586,8 -528,7 +587,8 @@@ static void end_align_handler(struct re
        strbuf_release(&s);
  }
  
 -static void align_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state)
 +static int align_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
 +                            struct strbuf *unused_err)
  {
        struct ref_formatting_stack *new_stack;
  
        new_stack = state->stack;
        new_stack->at_end = end_align_handler;
        new_stack->at_end_data = &atomv->atom->u.align;
 +      return 0;
  }
  
  static void if_then_else_handler(struct ref_formatting_stack **stack)
        free(if_then_else);
  }
  
 -static void if_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state)
 +static int if_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
 +                         struct strbuf *unused_err)
  {
        struct ref_formatting_stack *new_stack;
        struct if_then_else *if_then_else = xcalloc(sizeof(struct if_then_else), 1);
        new_stack = state->stack;
        new_stack->at_end = if_then_else_handler;
        new_stack->at_end_data = if_then_else;
 +      return 0;
  }
  
  static int is_empty(const char *s)
        return 1;
  }
  
 -static void then_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state)
 +static int then_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
 +                           struct strbuf *err)
  {
        struct ref_formatting_stack *cur = state->stack;
        struct if_then_else *if_then_else = NULL;
        if (cur->at_end == if_then_else_handler)
                if_then_else = (struct if_then_else *)cur->at_end_data;
        if (!if_then_else)
 -              die(_("format: %%(then) atom used without an %%(if) atom"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(then) atom used without an %%(if) atom"));
        if (if_then_else->then_atom_seen)
 -              die(_("format: %%(then) atom used more than once"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(then) atom used more than once"));
        if (if_then_else->else_atom_seen)
 -              die(_("format: %%(then) atom used after %%(else)"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(then) atom used after %%(else)"));
        if_then_else->then_atom_seen = 1;
        /*
         * If the 'equals' or 'notequals' attribute is used then
        } else if (cur->output.len && !is_empty(cur->output.buf))
                if_then_else->condition_satisfied = 1;
        strbuf_reset(&cur->output);
 +      return 0;
  }
  
 -static void else_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state)
 +static int else_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
 +                           struct strbuf *err)
  {
        struct ref_formatting_stack *prev = state->stack;
        struct if_then_else *if_then_else = NULL;
        if (prev->at_end == if_then_else_handler)
                if_then_else = (struct if_then_else *)prev->at_end_data;
        if (!if_then_else)
 -              die(_("format: %%(else) atom used without an %%(if) atom"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without an %%(if) atom"));
        if (!if_then_else->then_atom_seen)
 -              die(_("format: %%(else) atom used without a %%(then) atom"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without a %%(then) atom"));
        if (if_then_else->else_atom_seen)
 -              die(_("format: %%(else) atom used more than once"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(else) atom used more than once"));
        if_then_else->else_atom_seen = 1;
        push_stack_element(&state->stack);
        state->stack->at_end_data = prev->at_end_data;
        state->stack->at_end = prev->at_end;
 +      return 0;
  }
  
 -static void end_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state)
 +static int end_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
 +                          struct strbuf *err)
  {
        struct ref_formatting_stack *current = state->stack;
        struct strbuf s = STRBUF_INIT;
  
        if (!current->at_end)
 -              die(_("format: %%(end) atom used without corresponding atom"));
 +              return strbuf_addf_ret(err, -1, _("format: %%(end) atom used without corresponding atom"));
        current->at_end(&state->stack);
  
        /*  Stack may have been popped within at_end(), hence reset the current pointer */
        }
        strbuf_release(&s);
        pop_stack_element(&state->stack);
 +      return 0;
  }
  
  /*
@@@ -771,21 -703,17 +772,21 @@@ int verify_ref_format(struct ref_forma
  
        format->need_color_reset_at_eol = 0;
        for (cp = format->format; *cp && (sp = find_next(cp)); ) {
 +              struct strbuf err = STRBUF_INIT;
                const char *color, *ep = strchr(sp, ')');
                int at;
  
                if (!ep)
                        return error(_("malformed format string %s"), sp);
                /* sp points at "%(" and ep points at the closing ")" */
 -              at = parse_ref_filter_atom(format, sp + 2, ep);
 +              at = parse_ref_filter_atom(format, sp + 2, ep, &err);
 +              if (at < 0)
 +                      die("%s", err.buf);
                cp = ep + 1;
  
                if (skip_prefix(used_atom[at].name, "color:", &color))
                        format->need_color_reset_at_eol = !!strcmp(color, "reset");
 +              strbuf_release(&err);
        }
        if (format->need_color_reset_at_eol && !want_color(format->use_color))
                format->need_color_reset_at_eol = 0;
  static void *get_obj(const struct object_id *oid, struct object **obj, unsigned long *sz, int *eaten)
  {
        enum object_type type;
 -      void *buf = read_sha1_file(oid->hash, &type, sz);
 +      void *buf = read_object_file(oid, &type, sz);
  
        if (buf)
                *obj = parse_object_buffer(oid, type, *sz, buf, eaten);
        return buf;
  }
  
 -static int grab_objectname(const char *name, const unsigned char *sha1,
 +static int grab_objectname(const char *name, const struct object_id *oid,
                           struct atom_value *v, struct used_atom *atom)
  {
        if (starts_with(name, "objectname")) {
                if (atom->u.objectname.option == O_SHORT) {
 -                      v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
 +                      v->s = xstrdup(find_unique_abbrev(oid, DEFAULT_ABBREV));
                        return 1;
                } else if (atom->u.objectname.option == O_FULL) {
 -                      v->s = xstrdup(sha1_to_hex(sha1));
 +                      v->s = xstrdup(oid_to_hex(oid));
                        return 1;
                } else if (atom->u.objectname.option == O_LENGTH) {
 -                      v->s = xstrdup(find_unique_abbrev(sha1, atom->u.objectname.length));
 +                      v->s = xstrdup(find_unique_abbrev(oid, atom->u.objectname.length));
                        return 1;
                } else
 -                      die("BUG: unknown %%(objectname) option");
 +                      BUG("unknown %%(objectname) option");
        }
        return 0;
  }
@@@ -848,7 -776,7 +849,7 @@@ static void grab_common_values(struct a
                        v->s = xstrfmt("%lu", sz);
                }
                else if (deref)
 -                      grab_objectname(name, obj->oid.hash, v, &used_atom[i]);
 +                      grab_objectname(name, &obj->oid, v, &used_atom[i]);
        }
  }
  
@@@ -1322,8 -1250,8 +1323,8 @@@ static void fill_remote_ref_details(str
        if (atom->u.remote_ref.option == RR_REF)
                *s = show_ref(&atom->u.remote_ref.refname, refname);
        else if (atom->u.remote_ref.option == RR_TRACK) {
 -              if (stat_tracking_info(branch, &num_ours,
 -                                     &num_theirs, NULL)) {
 +              if (stat_tracking_info(branch, &num_ours, &num_theirs,
 +                                     NULL, AHEAD_BEHIND_FULL) < 0) {
                        *s = xstrdup(msgs.gone);
                } else if (!num_ours && !num_theirs)
                        *s = "";
                        free((void *)to_free);
                }
        } else if (atom->u.remote_ref.option == RR_TRACKSHORT) {
 -              if (stat_tracking_info(branch, &num_ours,
 -                                     &num_theirs, NULL))
 +              if (stat_tracking_info(branch, &num_ours, &num_theirs,
 +                                     NULL, AHEAD_BEHIND_FULL) < 0)
                        return;
  
                if (!num_ours && !num_theirs)
                else
                        *s = "";
        } else
 -              die("BUG: unhandled RR_* enum");
 +              BUG("unhandled RR_* enum");
  }
  
  char *get_head_description(void)
        memset(&state, 0, sizeof(state));
        wt_status_get_state(&state, 1);
        if (state.rebase_in_progress ||
 -          state.rebase_interactive_in_progress)
 -              strbuf_addf(&desc, _("(no branch, rebasing %s)"),
 -                          state.branch);
 -      else if (state.bisect_in_progress)
 +          state.rebase_interactive_in_progress) {
 +              if (state.branch)
 +                      strbuf_addf(&desc, _("(no branch, rebasing %s)"),
 +                                  state.branch);
 +              else
 +                      strbuf_addf(&desc, _("(no branch, rebasing detached HEAD %s)"),
 +                                  state.detached_from);
 +      } else if (state.bisect_in_progress)
                strbuf_addf(&desc, _("(no branch, bisect started on %s)"),
                            state.branch);
        else if (state.detached_from) {
@@@ -1431,33 -1355,15 +1432,33 @@@ static const char *get_refname(struct u
        return show_ref(&atom->u.refname, ref->refname);
  }
  
 +static int get_object(struct ref_array_item *ref, const struct object_id *oid,
 +                     int deref, struct object **obj, struct strbuf *err)
 +{
 +      int eaten;
 +      int ret = 0;
 +      unsigned long size;
 +      void *buf = get_obj(oid, obj, &size, &eaten);
 +      if (!buf)
 +              ret = strbuf_addf_ret(err, -1, _("missing object %s for %s"),
 +                                    oid_to_hex(oid), ref->refname);
 +      else if (!*obj)
 +              ret = strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"),
 +                                    oid_to_hex(oid), ref->refname);
 +      else
 +              grab_values(ref->value, deref, *obj, buf, size);
 +      if (!eaten)
 +              free(buf);
 +      return ret;
 +}
 +
  /*
   * Parse the object referred by ref, and grab needed value.
   */
 -static void populate_value(struct ref_array_item *ref)
 +static int populate_value(struct ref_array_item *ref, struct strbuf *err)
  {
 -      void *buf;
        struct object *obj;
 -      int eaten, i;
 -      unsigned long size;
 +      int i;
        const struct object_id *tagged;
  
        ref->value = xcalloc(used_atom_cnt, sizeof(struct atom_value));
                                v->s = xstrdup(buf + 1);
                        }
                        continue;
 -              } else if (!deref && grab_objectname(name, ref->objectname.hash, v, atom)) {
 +              } else if (!deref && grab_objectname(name, &ref->objectname, v, atom)) {
                        continue;
                } else if (!strcmp(name, "HEAD")) {
                        if (atom->u.head && !strcmp(ref->refname, atom->u.head))
        for (i = 0; i < used_atom_cnt; i++) {
                struct atom_value *v = &ref->value[i];
                if (v->s == NULL)
 -                      goto need_obj;
 +                      break;
        }
 -      return;
 -
 - need_obj:
 -      buf = get_obj(&ref->objectname, &obj, &size, &eaten);
 -      if (!buf)
 -              die(_("missing object %s for %s"),
 -                  oid_to_hex(&ref->objectname), ref->refname);
 -      if (!obj)
 -              die(_("parse_object_buffer failed on %s for %s"),
 -                  oid_to_hex(&ref->objectname), ref->refname);
 +      if (used_atom_cnt <= i)
 +              return 0;
  
 -      grab_values(ref->value, 0, obj, buf, size);
 -      if (!eaten)
 -              free(buf);
 +      if (get_object(ref, &ref->objectname, 0, &obj, err))
 +              return -1;
  
        /*
         * If there is no atom that wants to know about tagged
         * object, we are done.
         */
        if (!need_tagged || (obj->type != OBJ_TAG))
 -              return;
 +              return 0;
  
        /*
         * If it is a tag object, see if we use a value that derefs
         * is not consistent with what deref_tag() does
         * which peels the onion to the core.
         */
 -      buf = get_obj(tagged, &obj, &size, &eaten);
 -      if (!buf)
 -              die(_("missing object %s for %s"),
 -                  oid_to_hex(tagged), ref->refname);
 -      if (!obj)
 -              die(_("parse_object_buffer failed on %s for %s"),
 -                  oid_to_hex(tagged), ref->refname);
 -      grab_values(ref->value, 1, obj, buf, size);
 -      if (!eaten)
 -              free(buf);
 +      return get_object(ref, tagged, 1, &obj, err);
  }
  
  /*
   * Given a ref, return the value for the atom.  This lazily gets value
   * out of the object by calling populate value.
   */
 -static void get_ref_atom_value(struct ref_array_item *ref, int atom, struct atom_value **v)
 +static int get_ref_atom_value(struct ref_array_item *ref, int atom,
 +                            struct atom_value **v, struct strbuf *err)
  {
        if (!ref->value) {
 -              populate_value(ref);
 +              if (populate_value(ref, err))
 +                      return -1;
                fill_missing_values(ref->value);
        }
        *v = &ref->value[atom];
 +      return 0;
  }
  
  /*
@@@ -1662,12 -1583,13 +1663,13 @@@ static int in_commit_list(const struct 
  }
  
  /*
-  * Test whether the candidate or one of its parents is contained in the list.
+  * Test whether the candidate is contained in the list.
   * Do not recurse to find out, though, but return -1 if inconclusive.
   */
  static enum contains_result contains_test(struct commit *candidate,
                                          const struct commit_list *want,
-                                         struct contains_cache *cache)
+                                         struct contains_cache *cache,
+                                         uint32_t cutoff)
  {
        enum contains_result *cached = contains_cache_at(cache, candidate);
  
  
        /* Otherwise, we don't know; prepare to recurse */
        parse_commit_or_die(candidate);
+       if (candidate->generation < cutoff)
+               return CONTAINS_NO;
        return CONTAINS_UNKNOWN;
  }
  
@@@ -1698,8 -1624,18 +1704,18 @@@ static enum contains_result contains_ta
                                              struct contains_cache *cache)
  {
        struct contains_stack contains_stack = { 0, 0, NULL };
-       enum contains_result result = contains_test(candidate, want, cache);
+       enum contains_result result;
+       uint32_t cutoff = GENERATION_NUMBER_INFINITY;
+       const struct commit_list *p;
+       for (p = want; p; p = p->next) {
+               struct commit *c = p->item;
+               load_commit_graph_info(c);
+               if (c->generation < cutoff)
+                       cutoff = c->generation;
+       }
  
+       result = contains_test(candidate, want, cache, cutoff);
        if (result != CONTAINS_UNKNOWN)
                return result;
  
                 * If we just popped the stack, parents->item has been marked,
                 * therefore contains_test will return a meaningful yes/no.
                 */
-               else switch (contains_test(parents->item, want, cache)) {
+               else switch (contains_test(parents->item, want, cache, cutoff)) {
                case CONTAINS_YES:
                        *contains_cache_at(cache, commit) = CONTAINS_YES;
                        contains_stack.nr--;
                }
        }
        free(contains_stack.contains_stack);
-       return contains_test(candidate, want, cache);
+       return contains_test(candidate, want, cache, cutoff);
  }
  
  static int commit_contains(struct ref_filter *filter, struct commit *commit,
@@@ -1907,30 -1843,15 +1923,30 @@@ static const struct object_id *match_po
        return NULL;
  }
  
 -/* Allocate space for a new ref_array_item and copy the objectname and flag to it */
 +/*
 + * Allocate space for a new ref_array_item and copy the name and oid to it.
 + *
 + * Callers can then fill in other struct members at their leisure.
 + */
  static struct ref_array_item *new_ref_array_item(const char *refname,
 -                                               const unsigned char *objectname,
 -                                               int flag)
 +                                               const struct object_id *oid)
  {
        struct ref_array_item *ref;
 +
        FLEX_ALLOC_STR(ref, refname, refname);
 -      hashcpy(ref->objectname.hash, objectname);
 -      ref->flag = flag;
 +      oidcpy(&ref->objectname, oid);
 +
 +      return ref;
 +}
 +
 +struct ref_array_item *ref_array_push(struct ref_array *array,
 +                                    const char *refname,
 +                                    const struct object_id *oid)
 +{
 +      struct ref_array_item *ref = new_ref_array_item(refname, oid);
 +
 +      ALLOC_GROW(array->items, array->nr + 1, array->alloc);
 +      array->items[array->nr++] = ref;
  
        return ref;
  }
@@@ -2025,11 -1946,12 +2041,11 @@@ static int ref_filter_handler(const cha
         * to do its job and the resulting list may yet to be pruned
         * by maxcount logic.
         */
 -      ref = new_ref_array_item(refname, oid->hash, flag);
 +      ref = ref_array_push(ref_cbdata->array, refname, oid);
        ref->commit = commit;
 -
 -      REALLOC_ARRAY(ref_cbdata->array->items, ref_cbdata->array->nr + 1);
 -      ref_cbdata->array->items[ref_cbdata->array->nr++] = ref;
 +      ref->flag = flag;
        ref->kind = kind;
 +
        return 0;
  }
  
@@@ -2154,13 -2076,9 +2170,13 @@@ static int cmp_ref_sorting(struct ref_s
        int cmp;
        cmp_type cmp_type = used_atom[s->atom].type;
        int (*cmp_fn)(const char *, const char *);
 +      struct strbuf err = STRBUF_INIT;
  
 -      get_ref_atom_value(a, s->atom, &va);
 -      get_ref_atom_value(b, s->atom, &vb);
 +      if (get_ref_atom_value(a, s->atom, &va, &err))
 +              die("%s", err.buf);
 +      if (get_ref_atom_value(b, s->atom, &vb, &err))
 +              die("%s", err.buf);
 +      strbuf_release(&err);
        cmp_fn = s->ignore_case ? strcasecmp : strcmp;
        if (s->version)
                cmp = versioncmp(va->s, vb->s);
@@@ -2219,10 -2137,9 +2235,10 @@@ static void append_literal(const char *
        }
  }
  
 -void format_ref_array_item(struct ref_array_item *info,
 +int format_ref_array_item(struct ref_array_item *info,
                           const struct ref_format *format,
 -                         struct strbuf *final_buf)
 +                         struct strbuf *final_buf,
 +                         struct strbuf *error_buf)
  {
        const char *cp, *sp, *ep;
        struct ref_formatting_state state = REF_FORMATTING_STATE_INIT;
  
        for (cp = format->format; *cp && (sp = find_next(cp)); cp = ep + 1) {
                struct atom_value *atomv;
 +              int pos;
  
                ep = strchr(sp, ')');
                if (cp < sp)
                        append_literal(cp, sp, &state);
 -              get_ref_atom_value(info,
 -                                 parse_ref_filter_atom(format, sp + 2, ep),
 -                                 &atomv);
 -              atomv->handler(atomv, &state);
 +              pos = parse_ref_filter_atom(format, sp + 2, ep, error_buf);
 +              if (pos < 0 || get_ref_atom_value(info, pos, &atomv, error_buf) ||
 +                  atomv->handler(atomv, &state, error_buf)) {
 +                      pop_stack_element(&state.stack);
 +                      return -1;
 +              }
        }
        if (*cp) {
                sp = cp + strlen(cp);
        if (format->need_color_reset_at_eol) {
                struct atom_value resetv;
                resetv.s = GIT_COLOR_RESET;
 -              append_atom(&resetv, &state);
 +              if (append_atom(&resetv, &state, error_buf)) {
 +                      pop_stack_element(&state.stack);
 +                      return -1;
 +              }
 +      }
 +      if (state.stack->prev) {
 +              pop_stack_element(&state.stack);
 +              return strbuf_addf_ret(error_buf, -1, _("format: %%(end) atom missing"));
        }
 -      if (state.stack->prev)
 -              die(_("format: %%(end) atom missing"));
        strbuf_addbuf(final_buf, &state.stack->output);
        pop_stack_element(&state.stack);
 +      return 0;
  }
  
  void show_ref_array_item(struct ref_array_item *info,
                         const struct ref_format *format)
  {
        struct strbuf final_buf = STRBUF_INIT;
 +      struct strbuf error_buf = STRBUF_INIT;
  
 -      format_ref_array_item(info, format, &final_buf);
 +      if (format_ref_array_item(info, format, &final_buf, &error_buf))
 +              die("%s", error_buf.buf);
        fwrite(final_buf.buf, 1, final_buf.len, stdout);
 +      strbuf_release(&error_buf);
        strbuf_release(&final_buf);
        putchar('\n');
  }
  
 -void pretty_print_ref(const char *name, const unsigned char *sha1,
 +void pretty_print_ref(const char *name, const struct object_id *oid,
                      const struct ref_format *format)
  {
        struct ref_array_item *ref_item;
 -      ref_item = new_ref_array_item(name, sha1, 0);
 +      ref_item = new_ref_array_item(name, oid);
        ref_item->kind = ref_kind_from_refname(name);
        show_ref_array_item(ref_item, format);
        free_array_item(ref_item);
@@@ -2297,12 -2202,7 +2313,12 @@@ static int parse_sorting_atom(const cha
         */
        struct ref_format dummy = REF_FORMAT_INIT;
        const char *end = atom + strlen(atom);
 -      return parse_ref_filter_atom(&dummy, atom, end);
 +      struct strbuf err = STRBUF_INIT;
 +      int res = parse_ref_filter_atom(&dummy, atom, end, &err);
 +      if (res < 0)
 +              die("%s", err.buf);
 +      strbuf_release(&err);
 +      return res;
  }
  
  /*  If no sorting option is given, use refname to sort as default */
diff --combined sha1-file.c
index 695e5c62764cf4befe09467f1a658b25c01baba1,0000000000000000000000000000000000000000..de4839e634c02cb7497f05a3a4597b9fa5123e32
mode 100644,000000..100644
--- /dev/null
@@@ -1,2281 -1,0 +1,2281 @@@
-       if (parse_commit_buffer(&c, buf, size))
 +/*
 + * GIT - The information manager from hell
 + *
 + * Copyright (C) Linus Torvalds, 2005
 + *
 + * This handles basic git sha1 object files - packing, unpacking,
 + * creation etc.
 + */
 +#include "cache.h"
 +#include "config.h"
 +#include "string-list.h"
 +#include "lockfile.h"
 +#include "delta.h"
 +#include "pack.h"
 +#include "blob.h"
 +#include "commit.h"
 +#include "run-command.h"
 +#include "tag.h"
 +#include "tree.h"
 +#include "tree-walk.h"
 +#include "refs.h"
 +#include "pack-revindex.h"
 +#include "sha1-lookup.h"
 +#include "bulk-checkin.h"
 +#include "repository.h"
 +#include "replace-object.h"
 +#include "streaming.h"
 +#include "dir.h"
 +#include "list.h"
 +#include "mergesort.h"
 +#include "quote.h"
 +#include "packfile.h"
 +#include "fetch-object.h"
 +#include "object-store.h"
 +
 +/* The maximum size for an object header. */
 +#define MAX_HEADER_LEN 32
 +
 +
 +#define EMPTY_TREE_SHA1_BIN_LITERAL \
 +       "\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
 +       "\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
 +
 +#define EMPTY_BLOB_SHA1_BIN_LITERAL \
 +      "\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
 +      "\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
 +
 +const unsigned char null_sha1[GIT_MAX_RAWSZ];
 +const struct object_id null_oid;
 +static const struct object_id empty_tree_oid = {
 +      EMPTY_TREE_SHA1_BIN_LITERAL
 +};
 +static const struct object_id empty_blob_oid = {
 +      EMPTY_BLOB_SHA1_BIN_LITERAL
 +};
 +
 +static void git_hash_sha1_init(git_hash_ctx *ctx)
 +{
 +      git_SHA1_Init(&ctx->sha1);
 +}
 +
 +static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
 +{
 +      git_SHA1_Update(&ctx->sha1, data, len);
 +}
 +
 +static void git_hash_sha1_final(unsigned char *hash, git_hash_ctx *ctx)
 +{
 +      git_SHA1_Final(hash, &ctx->sha1);
 +}
 +
 +static void git_hash_unknown_init(git_hash_ctx *ctx)
 +{
 +      die("trying to init unknown hash");
 +}
 +
 +static void git_hash_unknown_update(git_hash_ctx *ctx, const void *data, size_t len)
 +{
 +      die("trying to update unknown hash");
 +}
 +
 +static void git_hash_unknown_final(unsigned char *hash, git_hash_ctx *ctx)
 +{
 +      die("trying to finalize unknown hash");
 +}
 +
 +const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
 +      {
 +              NULL,
 +              0x00000000,
 +              0,
 +              0,
 +              git_hash_unknown_init,
 +              git_hash_unknown_update,
 +              git_hash_unknown_final,
 +              NULL,
 +              NULL,
 +      },
 +      {
 +              "sha-1",
 +              /* "sha1", big-endian */
 +              0x73686131,
 +              GIT_SHA1_RAWSZ,
 +              GIT_SHA1_HEXSZ,
 +              git_hash_sha1_init,
 +              git_hash_sha1_update,
 +              git_hash_sha1_final,
 +              &empty_tree_oid,
 +              &empty_blob_oid,
 +      },
 +};
 +
 +const char *empty_tree_oid_hex(void)
 +{
 +      static char buf[GIT_MAX_HEXSZ + 1];
 +      return oid_to_hex_r(buf, the_hash_algo->empty_tree);
 +}
 +
 +const char *empty_blob_oid_hex(void)
 +{
 +      static char buf[GIT_MAX_HEXSZ + 1];
 +      return oid_to_hex_r(buf, the_hash_algo->empty_blob);
 +}
 +
 +/*
 + * This is meant to hold a *small* number of objects that you would
 + * want read_sha1_file() to be able to return, but yet you do not want
 + * to write them into the object store (e.g. a browse-only
 + * application).
 + */
 +static struct cached_object {
 +      struct object_id oid;
 +      enum object_type type;
 +      void *buf;
 +      unsigned long size;
 +} *cached_objects;
 +static int cached_object_nr, cached_object_alloc;
 +
 +static struct cached_object empty_tree = {
 +      { EMPTY_TREE_SHA1_BIN_LITERAL },
 +      OBJ_TREE,
 +      "",
 +      0
 +};
 +
 +static struct cached_object *find_cached_object(const struct object_id *oid)
 +{
 +      int i;
 +      struct cached_object *co = cached_objects;
 +
 +      for (i = 0; i < cached_object_nr; i++, co++) {
 +              if (!oidcmp(&co->oid, oid))
 +                      return co;
 +      }
 +      if (!oidcmp(oid, the_hash_algo->empty_tree))
 +              return &empty_tree;
 +      return NULL;
 +}
 +
 +
 +static int get_conv_flags(unsigned flags)
 +{
 +      if (flags & HASH_RENORMALIZE)
 +              return CONV_EOL_RENORMALIZE;
 +      else if (flags & HASH_WRITE_OBJECT)
 +              return global_conv_flags_eol | CONV_WRITE_OBJECT;
 +      else
 +              return 0;
 +}
 +
 +
 +int mkdir_in_gitdir(const char *path)
 +{
 +      if (mkdir(path, 0777)) {
 +              int saved_errno = errno;
 +              struct stat st;
 +              struct strbuf sb = STRBUF_INIT;
 +
 +              if (errno != EEXIST)
 +                      return -1;
 +              /*
 +               * Are we looking at a path in a symlinked worktree
 +               * whose original repository does not yet have it?
 +               * e.g. .git/rr-cache pointing at its original
 +               * repository in which the user hasn't performed any
 +               * conflict resolution yet?
 +               */
 +              if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 +                  strbuf_readlink(&sb, path, st.st_size) ||
 +                  !is_absolute_path(sb.buf) ||
 +                  mkdir(sb.buf, 0777)) {
 +                      strbuf_release(&sb);
 +                      errno = saved_errno;
 +                      return -1;
 +              }
 +              strbuf_release(&sb);
 +      }
 +      return adjust_shared_perm(path);
 +}
 +
 +enum scld_error safe_create_leading_directories(char *path)
 +{
 +      char *next_component = path + offset_1st_component(path);
 +      enum scld_error ret = SCLD_OK;
 +
 +      while (ret == SCLD_OK && next_component) {
 +              struct stat st;
 +              char *slash = next_component, slash_character;
 +
 +              while (*slash && !is_dir_sep(*slash))
 +                      slash++;
 +
 +              if (!*slash)
 +                      break;
 +
 +              next_component = slash + 1;
 +              while (is_dir_sep(*next_component))
 +                      next_component++;
 +              if (!*next_component)
 +                      break;
 +
 +              slash_character = *slash;
 +              *slash = '\0';
 +              if (!stat(path, &st)) {
 +                      /* path exists */
 +                      if (!S_ISDIR(st.st_mode)) {
 +                              errno = ENOTDIR;
 +                              ret = SCLD_EXISTS;
 +                      }
 +              } else if (mkdir(path, 0777)) {
 +                      if (errno == EEXIST &&
 +                          !stat(path, &st) && S_ISDIR(st.st_mode))
 +                              ; /* somebody created it since we checked */
 +                      else if (errno == ENOENT)
 +                              /*
 +                               * Either mkdir() failed because
 +                               * somebody just pruned the containing
 +                               * directory, or stat() failed because
 +                               * the file that was in our way was
 +                               * just removed.  Either way, inform
 +                               * the caller that it might be worth
 +                               * trying again:
 +                               */
 +                              ret = SCLD_VANISHED;
 +                      else
 +                              ret = SCLD_FAILED;
 +              } else if (adjust_shared_perm(path)) {
 +                      ret = SCLD_PERMS;
 +              }
 +              *slash = slash_character;
 +      }
 +      return ret;
 +}
 +
 +enum scld_error safe_create_leading_directories_const(const char *path)
 +{
 +      int save_errno;
 +      /* path points to cache entries, so xstrdup before messing with it */
 +      char *buf = xstrdup(path);
 +      enum scld_error result = safe_create_leading_directories(buf);
 +
 +      save_errno = errno;
 +      free(buf);
 +      errno = save_errno;
 +      return result;
 +}
 +
 +int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 +{
 +      /*
 +       * The number of times we will try to remove empty directories
 +       * in the way of path. This is only 1 because if another
 +       * process is racily creating directories that conflict with
 +       * us, we don't want to fight against them.
 +       */
 +      int remove_directories_remaining = 1;
 +
 +      /*
 +       * The number of times that we will try to create the
 +       * directories containing path. We are willing to attempt this
 +       * more than once, because another process could be trying to
 +       * clean up empty directories at the same time as we are
 +       * trying to create them.
 +       */
 +      int create_directories_remaining = 3;
 +
 +      /* A scratch copy of path, filled lazily if we need it: */
 +      struct strbuf path_copy = STRBUF_INIT;
 +
 +      int ret, save_errno;
 +
 +      /* Sanity check: */
 +      assert(*path);
 +
 +retry_fn:
 +      ret = fn(path, cb);
 +      save_errno = errno;
 +      if (!ret)
 +              goto out;
 +
 +      if (errno == EISDIR && remove_directories_remaining-- > 0) {
 +              /*
 +               * A directory is in the way. Maybe it is empty; try
 +               * to remove it:
 +               */
 +              if (!path_copy.len)
 +                      strbuf_addstr(&path_copy, path);
 +
 +              if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 +                      goto retry_fn;
 +      } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 +              /*
 +               * Maybe the containing directory didn't exist, or
 +               * maybe it was just deleted by a process that is
 +               * racing with us to clean up empty directories. Try
 +               * to create it:
 +               */
 +              enum scld_error scld_result;
 +
 +              if (!path_copy.len)
 +                      strbuf_addstr(&path_copy, path);
 +
 +              do {
 +                      scld_result = safe_create_leading_directories(path_copy.buf);
 +                      if (scld_result == SCLD_OK)
 +                              goto retry_fn;
 +              } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 +      }
 +
 +out:
 +      strbuf_release(&path_copy);
 +      errno = save_errno;
 +      return ret;
 +}
 +
 +static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 +{
 +      int i;
 +      for (i = 0; i < 20; i++) {
 +              static char hex[] = "0123456789abcdef";
 +              unsigned int val = sha1[i];
 +              strbuf_addch(buf, hex[val >> 4]);
 +              strbuf_addch(buf, hex[val & 0xf]);
 +              if (!i)
 +                      strbuf_addch(buf, '/');
 +      }
 +}
 +
 +void sha1_file_name(struct repository *r, struct strbuf *buf, const unsigned char *sha1)
 +{
 +      strbuf_addstr(buf, r->objects->objectdir);
 +      strbuf_addch(buf, '/');
 +      fill_sha1_path(buf, sha1);
 +}
 +
 +struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 +{
 +      strbuf_setlen(&alt->scratch, alt->base_len);
 +      return &alt->scratch;
 +}
 +
 +static const char *alt_sha1_path(struct alternate_object_database *alt,
 +                               const unsigned char *sha1)
 +{
 +      struct strbuf *buf = alt_scratch_buf(alt);
 +      fill_sha1_path(buf, sha1);
 +      return buf->buf;
 +}
 +
 +/*
 + * Return non-zero iff the path is usable as an alternate object database.
 + */
 +static int alt_odb_usable(struct raw_object_store *o,
 +                        struct strbuf *path,
 +                        const char *normalized_objdir)
 +{
 +      struct alternate_object_database *alt;
 +
 +      /* Detect cases where alternate disappeared */
 +      if (!is_directory(path->buf)) {
 +              error("object directory %s does not exist; "
 +                    "check .git/objects/info/alternates.",
 +                    path->buf);
 +              return 0;
 +      }
 +
 +      /*
 +       * Prevent the common mistake of listing the same
 +       * thing twice, or object directory itself.
 +       */
 +      for (alt = o->alt_odb_list; alt; alt = alt->next) {
 +              if (!fspathcmp(path->buf, alt->path))
 +                      return 0;
 +      }
 +      if (!fspathcmp(path->buf, normalized_objdir))
 +              return 0;
 +
 +      return 1;
 +}
 +
 +/*
 + * Prepare alternate object database registry.
 + *
 + * The variable alt_odb_list points at the list of struct
 + * alternate_object_database.  The elements on this list come from
 + * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 + * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 + * whose contents is similar to that environment variable but can be
 + * LF separated.  Its base points at a statically allocated buffer that
 + * contains "/the/directory/corresponding/to/.git/objects/...", while
 + * its name points just after the slash at the end of ".git/objects/"
 + * in the example above, and has enough space to hold 40-byte hex
 + * SHA1, an extra slash for the first level indirection, and the
 + * terminating NUL.
 + */
 +static void read_info_alternates(struct repository *r,
 +                               const char *relative_base,
 +                               int depth);
 +static int link_alt_odb_entry(struct repository *r, const char *entry,
 +      const char *relative_base, int depth, const char *normalized_objdir)
 +{
 +      struct alternate_object_database *ent;
 +      struct strbuf pathbuf = STRBUF_INIT;
 +
 +      if (!is_absolute_path(entry) && relative_base) {
 +              strbuf_realpath(&pathbuf, relative_base, 1);
 +              strbuf_addch(&pathbuf, '/');
 +      }
 +      strbuf_addstr(&pathbuf, entry);
 +
 +      if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 +              error("unable to normalize alternate object path: %s",
 +                    pathbuf.buf);
 +              strbuf_release(&pathbuf);
 +              return -1;
 +      }
 +
 +      /*
 +       * The trailing slash after the directory name is given by
 +       * this function at the end. Remove duplicates.
 +       */
 +      while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 +              strbuf_setlen(&pathbuf, pathbuf.len - 1);
 +
 +      if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir)) {
 +              strbuf_release(&pathbuf);
 +              return -1;
 +      }
 +
 +      ent = alloc_alt_odb(pathbuf.buf);
 +
 +      /* add the alternate entry */
 +      *r->objects->alt_odb_tail = ent;
 +      r->objects->alt_odb_tail = &(ent->next);
 +      ent->next = NULL;
 +
 +      /* recursively add alternates */
 +      read_info_alternates(r, pathbuf.buf, depth + 1);
 +
 +      strbuf_release(&pathbuf);
 +      return 0;
 +}
 +
 +static const char *parse_alt_odb_entry(const char *string,
 +                                     int sep,
 +                                     struct strbuf *out)
 +{
 +      const char *end;
 +
 +      strbuf_reset(out);
 +
 +      if (*string == '#') {
 +              /* comment; consume up to next separator */
 +              end = strchrnul(string, sep);
 +      } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 +              /*
 +               * quoted path; unquote_c_style has copied the
 +               * data for us and set "end". Broken quoting (e.g.,
 +               * an entry that doesn't end with a quote) falls
 +               * back to the unquoted case below.
 +               */
 +      } else {
 +              /* normal, unquoted path */
 +              end = strchrnul(string, sep);
 +              strbuf_add(out, string, end - string);
 +      }
 +
 +      if (*end)
 +              end++;
 +      return end;
 +}
 +
 +static void link_alt_odb_entries(struct repository *r, const char *alt,
 +                               int sep, const char *relative_base, int depth)
 +{
 +      struct strbuf objdirbuf = STRBUF_INIT;
 +      struct strbuf entry = STRBUF_INIT;
 +
 +      if (!alt || !*alt)
 +              return;
 +
 +      if (depth > 5) {
 +              error("%s: ignoring alternate object stores, nesting too deep.",
 +                              relative_base);
 +              return;
 +      }
 +
 +      strbuf_add_absolute_path(&objdirbuf, r->objects->objectdir);
 +      if (strbuf_normalize_path(&objdirbuf) < 0)
 +              die("unable to normalize object directory: %s",
 +                  objdirbuf.buf);
 +
 +      while (*alt) {
 +              alt = parse_alt_odb_entry(alt, sep, &entry);
 +              if (!entry.len)
 +                      continue;
 +              link_alt_odb_entry(r, entry.buf,
 +                                 relative_base, depth, objdirbuf.buf);
 +      }
 +      strbuf_release(&entry);
 +      strbuf_release(&objdirbuf);
 +}
 +
 +static void read_info_alternates(struct repository *r,
 +                               const char *relative_base,
 +                               int depth)
 +{
 +      char *path;
 +      struct strbuf buf = STRBUF_INIT;
 +
 +      path = xstrfmt("%s/info/alternates", relative_base);
 +      if (strbuf_read_file(&buf, path, 1024) < 0) {
 +              warn_on_fopen_errors(path);
 +              free(path);
 +              return;
 +      }
 +
 +      link_alt_odb_entries(r, buf.buf, '\n', relative_base, depth);
 +      strbuf_release(&buf);
 +      free(path);
 +}
 +
 +struct alternate_object_database *alloc_alt_odb(const char *dir)
 +{
 +      struct alternate_object_database *ent;
 +
 +      FLEX_ALLOC_STR(ent, path, dir);
 +      strbuf_init(&ent->scratch, 0);
 +      strbuf_addf(&ent->scratch, "%s/", dir);
 +      ent->base_len = ent->scratch.len;
 +
 +      return ent;
 +}
 +
 +void add_to_alternates_file(const char *reference)
 +{
 +      struct lock_file lock = LOCK_INIT;
 +      char *alts = git_pathdup("objects/info/alternates");
 +      FILE *in, *out;
 +      int found = 0;
 +
 +      hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 +      out = fdopen_lock_file(&lock, "w");
 +      if (!out)
 +              die_errno("unable to fdopen alternates lockfile");
 +
 +      in = fopen(alts, "r");
 +      if (in) {
 +              struct strbuf line = STRBUF_INIT;
 +
 +              while (strbuf_getline(&line, in) != EOF) {
 +                      if (!strcmp(reference, line.buf)) {
 +                              found = 1;
 +                              break;
 +                      }
 +                      fprintf_or_die(out, "%s\n", line.buf);
 +              }
 +
 +              strbuf_release(&line);
 +              fclose(in);
 +      }
 +      else if (errno != ENOENT)
 +              die_errno("unable to read alternates file");
 +
 +      if (found) {
 +              rollback_lock_file(&lock);
 +      } else {
 +              fprintf_or_die(out, "%s\n", reference);
 +              if (commit_lock_file(&lock))
 +                      die_errno("unable to move new alternates file into place");
 +              if (the_repository->objects->alt_odb_tail)
 +                      link_alt_odb_entries(the_repository, reference,
 +                                           '\n', NULL, 0);
 +      }
 +      free(alts);
 +}
 +
 +void add_to_alternates_memory(const char *reference)
 +{
 +      /*
 +       * Make sure alternates are initialized, or else our entry may be
 +       * overwritten when they are.
 +       */
 +      prepare_alt_odb(the_repository);
 +
 +      link_alt_odb_entries(the_repository, reference,
 +                           '\n', NULL, 0);
 +}
 +
 +/*
 + * Compute the exact path an alternate is at and returns it. In case of
 + * error NULL is returned and the human readable error is added to `err`
 + * `path` may be relative and should point to $GIT_DIR.
 + * `err` must not be null.
 + */
 +char *compute_alternate_path(const char *path, struct strbuf *err)
 +{
 +      char *ref_git = NULL;
 +      const char *repo, *ref_git_s;
 +      int seen_error = 0;
 +
 +      ref_git_s = real_path_if_valid(path);
 +      if (!ref_git_s) {
 +              seen_error = 1;
 +              strbuf_addf(err, _("path '%s' does not exist"), path);
 +              goto out;
 +      } else
 +              /*
 +               * Beware: read_gitfile(), real_path() and mkpath()
 +               * return static buffer
 +               */
 +              ref_git = xstrdup(ref_git_s);
 +
 +      repo = read_gitfile(ref_git);
 +      if (!repo)
 +              repo = read_gitfile(mkpath("%s/.git", ref_git));
 +      if (repo) {
 +              free(ref_git);
 +              ref_git = xstrdup(repo);
 +      }
 +
 +      if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 +              char *ref_git_git = mkpathdup("%s/.git", ref_git);
 +              free(ref_git);
 +              ref_git = ref_git_git;
 +      } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 +              struct strbuf sb = STRBUF_INIT;
 +              seen_error = 1;
 +              if (get_common_dir(&sb, ref_git)) {
 +                      strbuf_addf(err,
 +                                  _("reference repository '%s' as a linked "
 +                                    "checkout is not supported yet."),
 +                                  path);
 +                      goto out;
 +              }
 +
 +              strbuf_addf(err, _("reference repository '%s' is not a "
 +                                      "local repository."), path);
 +              goto out;
 +      }
 +
 +      if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 +              strbuf_addf(err, _("reference repository '%s' is shallow"),
 +                          path);
 +              seen_error = 1;
 +              goto out;
 +      }
 +
 +      if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 +              strbuf_addf(err,
 +                          _("reference repository '%s' is grafted"),
 +                          path);
 +              seen_error = 1;
 +              goto out;
 +      }
 +
 +out:
 +      if (seen_error) {
 +              FREE_AND_NULL(ref_git);
 +      }
 +
 +      return ref_git;
 +}
 +
 +int foreach_alt_odb(alt_odb_fn fn, void *cb)
 +{
 +      struct alternate_object_database *ent;
 +      int r = 0;
 +
 +      prepare_alt_odb(the_repository);
 +      for (ent = the_repository->objects->alt_odb_list; ent; ent = ent->next) {
 +              r = fn(ent, cb);
 +              if (r)
 +                      break;
 +      }
 +      return r;
 +}
 +
 +void prepare_alt_odb(struct repository *r)
 +{
 +      if (r->objects->alt_odb_tail)
 +              return;
 +
 +      r->objects->alt_odb_tail = &r->objects->alt_odb_list;
 +      link_alt_odb_entries(r, r->objects->alternate_db, PATH_SEP, NULL, 0);
 +
 +      read_info_alternates(r, r->objects->objectdir, 0);
 +}
 +
 +/* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 +static int freshen_file(const char *fn)
 +{
 +      struct utimbuf t;
 +      t.actime = t.modtime = time(NULL);
 +      return !utime(fn, &t);
 +}
 +
 +/*
 + * All of the check_and_freshen functions return 1 if the file exists and was
 + * freshened (if freshening was requested), 0 otherwise. If they return
 + * 0, you should not assume that it is safe to skip a write of the object (it
 + * either does not exist on disk, or has a stale mtime and may be subject to
 + * pruning).
 + */
 +int check_and_freshen_file(const char *fn, int freshen)
 +{
 +      if (access(fn, F_OK))
 +              return 0;
 +      if (freshen && !freshen_file(fn))
 +              return 0;
 +      return 1;
 +}
 +
 +static int check_and_freshen_local(const struct object_id *oid, int freshen)
 +{
 +      static struct strbuf buf = STRBUF_INIT;
 +
 +      strbuf_reset(&buf);
 +      sha1_file_name(the_repository, &buf, oid->hash);
 +
 +      return check_and_freshen_file(buf.buf, freshen);
 +}
 +
 +static int check_and_freshen_nonlocal(const struct object_id *oid, int freshen)
 +{
 +      struct alternate_object_database *alt;
 +      prepare_alt_odb(the_repository);
 +      for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 +              const char *path = alt_sha1_path(alt, oid->hash);
 +              if (check_and_freshen_file(path, freshen))
 +                      return 1;
 +      }
 +      return 0;
 +}
 +
 +static int check_and_freshen(const struct object_id *oid, int freshen)
 +{
 +      return check_and_freshen_local(oid, freshen) ||
 +             check_and_freshen_nonlocal(oid, freshen);
 +}
 +
 +int has_loose_object_nonlocal(const struct object_id *oid)
 +{
 +      return check_and_freshen_nonlocal(oid, 0);
 +}
 +
 +static int has_loose_object(const struct object_id *oid)
 +{
 +      return check_and_freshen(oid, 0);
 +}
 +
 +static void mmap_limit_check(size_t length)
 +{
 +      static size_t limit = 0;
 +      if (!limit) {
 +              limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 +              if (!limit)
 +                      limit = SIZE_MAX;
 +      }
 +      if (length > limit)
 +              die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 +                  (uintmax_t)length, (uintmax_t)limit);
 +}
 +
 +void *xmmap_gently(void *start, size_t length,
 +                int prot, int flags, int fd, off_t offset)
 +{
 +      void *ret;
 +
 +      mmap_limit_check(length);
 +      ret = mmap(start, length, prot, flags, fd, offset);
 +      if (ret == MAP_FAILED) {
 +              if (!length)
 +                      return NULL;
 +              release_pack_memory(length);
 +              ret = mmap(start, length, prot, flags, fd, offset);
 +      }
 +      return ret;
 +}
 +
 +void *xmmap(void *start, size_t length,
 +      int prot, int flags, int fd, off_t offset)
 +{
 +      void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 +      if (ret == MAP_FAILED)
 +              die_errno("mmap failed");
 +      return ret;
 +}
 +
 +/*
 + * With an in-core object data in "map", rehash it to make sure the
 + * object name actually matches "sha1" to detect object corruption.
 + * With "map" == NULL, try reading the object named with "sha1" using
 + * the streaming interface and rehash it to do the same.
 + */
 +int check_object_signature(const struct object_id *oid, void *map,
 +                         unsigned long size, const char *type)
 +{
 +      struct object_id real_oid;
 +      enum object_type obj_type;
 +      struct git_istream *st;
 +      git_hash_ctx c;
 +      char hdr[MAX_HEADER_LEN];
 +      int hdrlen;
 +
 +      if (map) {
 +              hash_object_file(map, size, type, &real_oid);
 +              return oidcmp(oid, &real_oid) ? -1 : 0;
 +      }
 +
 +      st = open_istream(oid, &obj_type, &size, NULL);
 +      if (!st)
 +              return -1;
 +
 +      /* Generate the header */
 +      hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(obj_type), size) + 1;
 +
 +      /* Sha1.. */
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, hdr, hdrlen);
 +      for (;;) {
 +              char buf[1024 * 16];
 +              ssize_t readlen = read_istream(st, buf, sizeof(buf));
 +
 +              if (readlen < 0) {
 +                      close_istream(st);
 +                      return -1;
 +              }
 +              if (!readlen)
 +                      break;
 +              the_hash_algo->update_fn(&c, buf, readlen);
 +      }
 +      the_hash_algo->final_fn(real_oid.hash, &c);
 +      close_istream(st);
 +      return oidcmp(oid, &real_oid) ? -1 : 0;
 +}
 +
 +int git_open_cloexec(const char *name, int flags)
 +{
 +      int fd;
 +      static int o_cloexec = O_CLOEXEC;
 +
 +      fd = open(name, flags | o_cloexec);
 +      if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 +              /* Try again w/o O_CLOEXEC: the kernel might not support it */
 +              o_cloexec &= ~O_CLOEXEC;
 +              fd = open(name, flags | o_cloexec);
 +      }
 +
 +#if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 +      {
 +              static int fd_cloexec = FD_CLOEXEC;
 +
 +              if (!o_cloexec && 0 <= fd && fd_cloexec) {
 +                      /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 +                      int flags = fcntl(fd, F_GETFD);
 +                      if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 +                              fd_cloexec = 0;
 +              }
 +      }
 +#endif
 +      return fd;
 +}
 +
 +/*
 + * Find "sha1" as a loose object in the local repository or in an alternate.
 + * Returns 0 on success, negative on failure.
 + *
 + * The "path" out-parameter will give the path of the object we found (if any).
 + * Note that it may point to static storage and is only valid until another
 + * call to sha1_file_name(), etc.
 + */
 +static int stat_sha1_file(struct repository *r, const unsigned char *sha1,
 +                        struct stat *st, const char **path)
 +{
 +      struct alternate_object_database *alt;
 +      static struct strbuf buf = STRBUF_INIT;
 +
 +      strbuf_reset(&buf);
 +      sha1_file_name(r, &buf, sha1);
 +      *path = buf.buf;
 +
 +      if (!lstat(*path, st))
 +              return 0;
 +
 +      prepare_alt_odb(r);
 +      errno = ENOENT;
 +      for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 +              *path = alt_sha1_path(alt, sha1);
 +              if (!lstat(*path, st))
 +                      return 0;
 +      }
 +
 +      return -1;
 +}
 +
 +/*
 + * Like stat_sha1_file(), but actually open the object and return the
 + * descriptor. See the caveats on the "path" parameter above.
 + */
 +static int open_sha1_file(struct repository *r,
 +                        const unsigned char *sha1, const char **path)
 +{
 +      int fd;
 +      struct alternate_object_database *alt;
 +      int most_interesting_errno;
 +      static struct strbuf buf = STRBUF_INIT;
 +
 +      strbuf_reset(&buf);
 +      sha1_file_name(r, &buf, sha1);
 +      *path = buf.buf;
 +
 +      fd = git_open(*path);
 +      if (fd >= 0)
 +              return fd;
 +      most_interesting_errno = errno;
 +
 +      prepare_alt_odb(r);
 +      for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 +              *path = alt_sha1_path(alt, sha1);
 +              fd = git_open(*path);
 +              if (fd >= 0)
 +                      return fd;
 +              if (most_interesting_errno == ENOENT)
 +                      most_interesting_errno = errno;
 +      }
 +      errno = most_interesting_errno;
 +      return -1;
 +}
 +
 +/*
 + * Map the loose object at "path" if it is not NULL, or the path found by
 + * searching for a loose object named "sha1".
 + */
 +static void *map_sha1_file_1(struct repository *r, const char *path,
 +                           const unsigned char *sha1, unsigned long *size)
 +{
 +      void *map;
 +      int fd;
 +
 +      if (path)
 +              fd = git_open(path);
 +      else
 +              fd = open_sha1_file(r, sha1, &path);
 +      map = NULL;
 +      if (fd >= 0) {
 +              struct stat st;
 +
 +              if (!fstat(fd, &st)) {
 +                      *size = xsize_t(st.st_size);
 +                      if (!*size) {
 +                              /* mmap() is forbidden on empty files */
 +                              error("object file %s is empty", path);
 +                              return NULL;
 +                      }
 +                      map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 +              }
 +              close(fd);
 +      }
 +      return map;
 +}
 +
 +void *map_sha1_file(struct repository *r,
 +                  const unsigned char *sha1, unsigned long *size)
 +{
 +      return map_sha1_file_1(r, NULL, sha1, size);
 +}
 +
 +static int unpack_sha1_short_header(git_zstream *stream,
 +                                  unsigned char *map, unsigned long mapsize,
 +                                  void *buffer, unsigned long bufsiz)
 +{
 +      /* Get the data stream */
 +      memset(stream, 0, sizeof(*stream));
 +      stream->next_in = map;
 +      stream->avail_in = mapsize;
 +      stream->next_out = buffer;
 +      stream->avail_out = bufsiz;
 +
 +      git_inflate_init(stream);
 +      return git_inflate(stream, 0);
 +}
 +
 +int unpack_sha1_header(git_zstream *stream,
 +                     unsigned char *map, unsigned long mapsize,
 +                     void *buffer, unsigned long bufsiz)
 +{
 +      int status = unpack_sha1_short_header(stream, map, mapsize,
 +                                            buffer, bufsiz);
 +
 +      if (status < Z_OK)
 +              return status;
 +
 +      /* Make sure we have the terminating NUL */
 +      if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 +              return -1;
 +      return 0;
 +}
 +
 +static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
 +                                      unsigned long mapsize, void *buffer,
 +                                      unsigned long bufsiz, struct strbuf *header)
 +{
 +      int status;
 +
 +      status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
 +      if (status < Z_OK)
 +              return -1;
 +
 +      /*
 +       * Check if entire header is unpacked in the first iteration.
 +       */
 +      if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 +              return 0;
 +
 +      /*
 +       * buffer[0..bufsiz] was not large enough.  Copy the partial
 +       * result out to header, and then append the result of further
 +       * reading the stream.
 +       */
 +      strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
 +      stream->next_out = buffer;
 +      stream->avail_out = bufsiz;
 +
 +      do {
 +              status = git_inflate(stream, 0);
 +              strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
 +              if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 +                      return 0;
 +              stream->next_out = buffer;
 +              stream->avail_out = bufsiz;
 +      } while (status != Z_STREAM_END);
 +      return -1;
 +}
 +
 +static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
 +{
 +      int bytes = strlen(buffer) + 1;
 +      unsigned char *buf = xmallocz(size);
 +      unsigned long n;
 +      int status = Z_OK;
 +
 +      n = stream->total_out - bytes;
 +      if (n > size)
 +              n = size;
 +      memcpy(buf, (char *) buffer + bytes, n);
 +      bytes = n;
 +      if (bytes <= size) {
 +              /*
 +               * The above condition must be (bytes <= size), not
 +               * (bytes < size).  In other words, even though we
 +               * expect no more output and set avail_out to zero,
 +               * the input zlib stream may have bytes that express
 +               * "this concludes the stream", and we *do* want to
 +               * eat that input.
 +               *
 +               * Otherwise we would not be able to test that we
 +               * consumed all the input to reach the expected size;
 +               * we also want to check that zlib tells us that all
 +               * went well with status == Z_STREAM_END at the end.
 +               */
 +              stream->next_out = buf + bytes;
 +              stream->avail_out = size - bytes;
 +              while (status == Z_OK)
 +                      status = git_inflate(stream, Z_FINISH);
 +      }
 +      if (status == Z_STREAM_END && !stream->avail_in) {
 +              git_inflate_end(stream);
 +              return buf;
 +      }
 +
 +      if (status < 0)
 +              error("corrupt loose object '%s'", sha1_to_hex(sha1));
 +      else if (stream->avail_in)
 +              error("garbage at end of loose object '%s'",
 +                    sha1_to_hex(sha1));
 +      free(buf);
 +      return NULL;
 +}
 +
 +/*
 + * We used to just use "sscanf()", but that's actually way
 + * too permissive for what we want to check. So do an anal
 + * object header parse by hand.
 + */
 +static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
 +                             unsigned int flags)
 +{
 +      const char *type_buf = hdr;
 +      unsigned long size;
 +      int type, type_len = 0;
 +
 +      /*
 +       * The type can be of any size but is followed by
 +       * a space.
 +       */
 +      for (;;) {
 +              char c = *hdr++;
 +              if (!c)
 +                      return -1;
 +              if (c == ' ')
 +                      break;
 +              type_len++;
 +      }
 +
 +      type = type_from_string_gently(type_buf, type_len, 1);
 +      if (oi->type_name)
 +              strbuf_add(oi->type_name, type_buf, type_len);
 +      /*
 +       * Set type to 0 if its an unknown object and
 +       * we're obtaining the type using '--allow-unknown-type'
 +       * option.
 +       */
 +      if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
 +              type = 0;
 +      else if (type < 0)
 +              die("invalid object type");
 +      if (oi->typep)
 +              *oi->typep = type;
 +
 +      /*
 +       * The length must follow immediately, and be in canonical
 +       * decimal format (ie "010" is not valid).
 +       */
 +      size = *hdr++ - '0';
 +      if (size > 9)
 +              return -1;
 +      if (size) {
 +              for (;;) {
 +                      unsigned long c = *hdr - '0';
 +                      if (c > 9)
 +                              break;
 +                      hdr++;
 +                      size = size * 10 + c;
 +              }
 +      }
 +
 +      if (oi->sizep)
 +              *oi->sizep = size;
 +
 +      /*
 +       * The length must be followed by a zero byte
 +       */
 +      return *hdr ? -1 : type;
 +}
 +
 +int parse_sha1_header(const char *hdr, unsigned long *sizep)
 +{
 +      struct object_info oi = OBJECT_INFO_INIT;
 +
 +      oi.sizep = sizep;
 +      return parse_sha1_header_extended(hdr, &oi, 0);
 +}
 +
 +static int sha1_loose_object_info(struct repository *r,
 +                                const unsigned char *sha1,
 +                                struct object_info *oi, int flags)
 +{
 +      int status = 0;
 +      unsigned long mapsize;
 +      void *map;
 +      git_zstream stream;
 +      char hdr[MAX_HEADER_LEN];
 +      struct strbuf hdrbuf = STRBUF_INIT;
 +      unsigned long size_scratch;
 +
 +      if (oi->delta_base_sha1)
 +              hashclr(oi->delta_base_sha1);
 +
 +      /*
 +       * If we don't care about type or size, then we don't
 +       * need to look inside the object at all. Note that we
 +       * do not optimize out the stat call, even if the
 +       * caller doesn't care about the disk-size, since our
 +       * return value implicitly indicates whether the
 +       * object even exists.
 +       */
 +      if (!oi->typep && !oi->type_name && !oi->sizep && !oi->contentp) {
 +              const char *path;
 +              struct stat st;
 +              if (stat_sha1_file(r, sha1, &st, &path) < 0)
 +                      return -1;
 +              if (oi->disk_sizep)
 +                      *oi->disk_sizep = st.st_size;
 +              return 0;
 +      }
 +
 +      map = map_sha1_file(r, sha1, &mapsize);
 +      if (!map)
 +              return -1;
 +
 +      if (!oi->sizep)
 +              oi->sizep = &size_scratch;
 +
 +      if (oi->disk_sizep)
 +              *oi->disk_sizep = mapsize;
 +      if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
 +              if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
 +                      status = error("unable to unpack %s header with --allow-unknown-type",
 +                                     sha1_to_hex(sha1));
 +      } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 +              status = error("unable to unpack %s header",
 +                             sha1_to_hex(sha1));
 +      if (status < 0)
 +              ; /* Do nothing */
 +      else if (hdrbuf.len) {
 +              if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
 +                      status = error("unable to parse %s header with --allow-unknown-type",
 +                                     sha1_to_hex(sha1));
 +      } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
 +              status = error("unable to parse %s header", sha1_to_hex(sha1));
 +
 +      if (status >= 0 && oi->contentp) {
 +              *oi->contentp = unpack_sha1_rest(&stream, hdr,
 +                                               *oi->sizep, sha1);
 +              if (!*oi->contentp) {
 +                      git_inflate_end(&stream);
 +                      status = -1;
 +              }
 +      } else
 +              git_inflate_end(&stream);
 +
 +      munmap(map, mapsize);
 +      if (status && oi->typep)
 +              *oi->typep = status;
 +      if (oi->sizep == &size_scratch)
 +              oi->sizep = NULL;
 +      strbuf_release(&hdrbuf);
 +      oi->whence = OI_LOOSE;
 +      return (status < 0) ? status : 0;
 +}
 +
 +int fetch_if_missing = 1;
 +
 +int oid_object_info_extended(struct repository *r, const struct object_id *oid,
 +                           struct object_info *oi, unsigned flags)
 +{
 +      static struct object_info blank_oi = OBJECT_INFO_INIT;
 +      struct pack_entry e;
 +      int rtype;
 +      const struct object_id *real = oid;
 +      int already_retried = 0;
 +
 +      if (flags & OBJECT_INFO_LOOKUP_REPLACE)
 +              real = lookup_replace_object(r, oid);
 +
 +      if (is_null_oid(real))
 +              return -1;
 +
 +      if (!oi)
 +              oi = &blank_oi;
 +
 +      if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
 +              struct cached_object *co = find_cached_object(real);
 +              if (co) {
 +                      if (oi->typep)
 +                              *(oi->typep) = co->type;
 +                      if (oi->sizep)
 +                              *(oi->sizep) = co->size;
 +                      if (oi->disk_sizep)
 +                              *(oi->disk_sizep) = 0;
 +                      if (oi->delta_base_sha1)
 +                              hashclr(oi->delta_base_sha1);
 +                      if (oi->type_name)
 +                              strbuf_addstr(oi->type_name, type_name(co->type));
 +                      if (oi->contentp)
 +                              *oi->contentp = xmemdupz(co->buf, co->size);
 +                      oi->whence = OI_CACHED;
 +                      return 0;
 +              }
 +      }
 +
 +      while (1) {
 +              if (find_pack_entry(r, real, &e))
 +                      break;
 +
 +              if (flags & OBJECT_INFO_IGNORE_LOOSE)
 +                      return -1;
 +
 +              /* Most likely it's a loose object. */
 +              if (!sha1_loose_object_info(r, real->hash, oi, flags))
 +                      return 0;
 +
 +              /* Not a loose object; someone else may have just packed it. */
 +              if (!(flags & OBJECT_INFO_QUICK)) {
 +                      reprepare_packed_git(r);
 +                      if (find_pack_entry(r, real, &e))
 +                              break;
 +              }
 +
 +              /* Check if it is a missing object */
 +              if (fetch_if_missing && repository_format_partial_clone &&
 +                  !already_retried && r == the_repository) {
 +                      /*
 +                       * TODO Investigate having fetch_object() return
 +                       * TODO error/success and stopping the music here.
 +                       * TODO Pass a repository struct through fetch_object,
 +                       * such that arbitrary repositories work.
 +                       */
 +                      fetch_object(repository_format_partial_clone, real->hash);
 +                      already_retried = 1;
 +                      continue;
 +              }
 +
 +              return -1;
 +      }
 +
 +      if (oi == &blank_oi)
 +              /*
 +               * We know that the caller doesn't actually need the
 +               * information below, so return early.
 +               */
 +              return 0;
 +      rtype = packed_object_info(r, e.p, e.offset, oi);
 +      if (rtype < 0) {
 +              mark_bad_packed_object(e.p, real->hash);
 +              return oid_object_info_extended(r, real, oi, 0);
 +      } else if (oi->whence == OI_PACKED) {
 +              oi->u.packed.offset = e.offset;
 +              oi->u.packed.pack = e.p;
 +              oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
 +                                       rtype == OBJ_OFS_DELTA);
 +      }
 +
 +      return 0;
 +}
 +
 +/* returns enum object_type or negative */
 +int oid_object_info(struct repository *r,
 +                  const struct object_id *oid,
 +                  unsigned long *sizep)
 +{
 +      enum object_type type;
 +      struct object_info oi = OBJECT_INFO_INIT;
 +
 +      oi.typep = &type;
 +      oi.sizep = sizep;
 +      if (oid_object_info_extended(r, oid, &oi,
 +                                    OBJECT_INFO_LOOKUP_REPLACE) < 0)
 +              return -1;
 +      return type;
 +}
 +
 +static void *read_object(const unsigned char *sha1, enum object_type *type,
 +                       unsigned long *size)
 +{
 +      struct object_id oid;
 +      struct object_info oi = OBJECT_INFO_INIT;
 +      void *content;
 +      oi.typep = type;
 +      oi.sizep = size;
 +      oi.contentp = &content;
 +
 +      hashcpy(oid.hash, sha1);
 +
 +      if (oid_object_info_extended(the_repository, &oid, &oi, 0) < 0)
 +              return NULL;
 +      return content;
 +}
 +
 +int pretend_object_file(void *buf, unsigned long len, enum object_type type,
 +                      struct object_id *oid)
 +{
 +      struct cached_object *co;
 +
 +      hash_object_file(buf, len, type_name(type), oid);
 +      if (has_sha1_file(oid->hash) || find_cached_object(oid))
 +              return 0;
 +      ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
 +      co = &cached_objects[cached_object_nr++];
 +      co->size = len;
 +      co->type = type;
 +      co->buf = xmalloc(len);
 +      memcpy(co->buf, buf, len);
 +      oidcpy(&co->oid, oid);
 +      return 0;
 +}
 +
 +/*
 + * This function dies on corrupt objects; the callers who want to
 + * deal with them should arrange to call read_object() and give error
 + * messages themselves.
 + */
 +void *read_object_file_extended(const struct object_id *oid,
 +                              enum object_type *type,
 +                              unsigned long *size,
 +                              int lookup_replace)
 +{
 +      void *data;
 +      const struct packed_git *p;
 +      const char *path;
 +      struct stat st;
 +      const struct object_id *repl = lookup_replace ?
 +              lookup_replace_object(the_repository, oid) : oid;
 +
 +      errno = 0;
 +      data = read_object(repl->hash, type, size);
 +      if (data)
 +              return data;
 +
 +      if (errno && errno != ENOENT)
 +              die_errno("failed to read object %s", oid_to_hex(oid));
 +
 +      /* die if we replaced an object with one that does not exist */
 +      if (repl != oid)
 +              die("replacement %s not found for %s",
 +                  oid_to_hex(repl), oid_to_hex(oid));
 +
 +      if (!stat_sha1_file(the_repository, repl->hash, &st, &path))
 +              die("loose object %s (stored in %s) is corrupt",
 +                  oid_to_hex(repl), path);
 +
 +      if ((p = has_packed_and_bad(repl->hash)) != NULL)
 +              die("packed object %s (stored in %s) is corrupt",
 +                  oid_to_hex(repl), p->pack_name);
 +
 +      return NULL;
 +}
 +
 +void *read_object_with_reference(const struct object_id *oid,
 +                               const char *required_type_name,
 +                               unsigned long *size,
 +                               struct object_id *actual_oid_return)
 +{
 +      enum object_type type, required_type;
 +      void *buffer;
 +      unsigned long isize;
 +      struct object_id actual_oid;
 +
 +      required_type = type_from_string(required_type_name);
 +      oidcpy(&actual_oid, oid);
 +      while (1) {
 +              int ref_length = -1;
 +              const char *ref_type = NULL;
 +
 +              buffer = read_object_file(&actual_oid, &type, &isize);
 +              if (!buffer)
 +                      return NULL;
 +              if (type == required_type) {
 +                      *size = isize;
 +                      if (actual_oid_return)
 +                              oidcpy(actual_oid_return, &actual_oid);
 +                      return buffer;
 +              }
 +              /* Handle references */
 +              else if (type == OBJ_COMMIT)
 +                      ref_type = "tree ";
 +              else if (type == OBJ_TAG)
 +                      ref_type = "object ";
 +              else {
 +                      free(buffer);
 +                      return NULL;
 +              }
 +              ref_length = strlen(ref_type);
 +
 +              if (ref_length + GIT_SHA1_HEXSZ > isize ||
 +                  memcmp(buffer, ref_type, ref_length) ||
 +                  get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
 +                      free(buffer);
 +                      return NULL;
 +              }
 +              free(buffer);
 +              /* Now we have the ID of the referred-to object in
 +               * actual_oid.  Check again. */
 +      }
 +}
 +
 +static void write_object_file_prepare(const void *buf, unsigned long len,
 +                                    const char *type, struct object_id *oid,
 +                                    char *hdr, int *hdrlen)
 +{
 +      git_hash_ctx c;
 +
 +      /* Generate the header */
 +      *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
 +
 +      /* Sha1.. */
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, hdr, *hdrlen);
 +      the_hash_algo->update_fn(&c, buf, len);
 +      the_hash_algo->final_fn(oid->hash, &c);
 +}
 +
 +/*
 + * Move the just written object into its final resting place.
 + */
 +int finalize_object_file(const char *tmpfile, const char *filename)
 +{
 +      int ret = 0;
 +
 +      if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
 +              goto try_rename;
 +      else if (link(tmpfile, filename))
 +              ret = errno;
 +
 +      /*
 +       * Coda hack - coda doesn't like cross-directory links,
 +       * so we fall back to a rename, which will mean that it
 +       * won't be able to check collisions, but that's not a
 +       * big deal.
 +       *
 +       * The same holds for FAT formatted media.
 +       *
 +       * When this succeeds, we just return.  We have nothing
 +       * left to unlink.
 +       */
 +      if (ret && ret != EEXIST) {
 +      try_rename:
 +              if (!rename(tmpfile, filename))
 +                      goto out;
 +              ret = errno;
 +      }
 +      unlink_or_warn(tmpfile);
 +      if (ret) {
 +              if (ret != EEXIST) {
 +                      return error_errno("unable to write sha1 filename %s", filename);
 +              }
 +              /* FIXME!!! Collision check here ? */
 +      }
 +
 +out:
 +      if (adjust_shared_perm(filename))
 +              return error("unable to set permission to '%s'", filename);
 +      return 0;
 +}
 +
 +static int write_buffer(int fd, const void *buf, size_t len)
 +{
 +      if (write_in_full(fd, buf, len) < 0)
 +              return error_errno("file write error");
 +      return 0;
 +}
 +
 +int hash_object_file(const void *buf, unsigned long len, const char *type,
 +                   struct object_id *oid)
 +{
 +      char hdr[MAX_HEADER_LEN];
 +      int hdrlen = sizeof(hdr);
 +      write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
 +      return 0;
 +}
 +
 +/* Finalize a file on disk, and close it. */
 +static void close_sha1_file(int fd)
 +{
 +      if (fsync_object_files)
 +              fsync_or_die(fd, "sha1 file");
 +      if (close(fd) != 0)
 +              die_errno("error when closing sha1 file");
 +}
 +
 +/* Size of directory component, including the ending '/' */
 +static inline int directory_size(const char *filename)
 +{
 +      const char *s = strrchr(filename, '/');
 +      if (!s)
 +              return 0;
 +      return s - filename + 1;
 +}
 +
 +/*
 + * This creates a temporary file in the same directory as the final
 + * 'filename'
 + *
 + * We want to avoid cross-directory filename renames, because those
 + * can have problems on various filesystems (FAT, NFS, Coda).
 + */
 +static int create_tmpfile(struct strbuf *tmp, const char *filename)
 +{
 +      int fd, dirlen = directory_size(filename);
 +
 +      strbuf_reset(tmp);
 +      strbuf_add(tmp, filename, dirlen);
 +      strbuf_addstr(tmp, "tmp_obj_XXXXXX");
 +      fd = git_mkstemp_mode(tmp->buf, 0444);
 +      if (fd < 0 && dirlen && errno == ENOENT) {
 +              /*
 +               * Make sure the directory exists; note that the contents
 +               * of the buffer are undefined after mkstemp returns an
 +               * error, so we have to rewrite the whole buffer from
 +               * scratch.
 +               */
 +              strbuf_reset(tmp);
 +              strbuf_add(tmp, filename, dirlen - 1);
 +              if (mkdir(tmp->buf, 0777) && errno != EEXIST)
 +                      return -1;
 +              if (adjust_shared_perm(tmp->buf))
 +                      return -1;
 +
 +              /* Try again */
 +              strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
 +              fd = git_mkstemp_mode(tmp->buf, 0444);
 +      }
 +      return fd;
 +}
 +
 +static int write_loose_object(const struct object_id *oid, char *hdr,
 +                            int hdrlen, const void *buf, unsigned long len,
 +                            time_t mtime)
 +{
 +      int fd, ret;
 +      unsigned char compressed[4096];
 +      git_zstream stream;
 +      git_hash_ctx c;
 +      struct object_id parano_oid;
 +      static struct strbuf tmp_file = STRBUF_INIT;
 +      static struct strbuf filename = STRBUF_INIT;
 +
 +      strbuf_reset(&filename);
 +      sha1_file_name(the_repository, &filename, oid->hash);
 +
 +      fd = create_tmpfile(&tmp_file, filename.buf);
 +      if (fd < 0) {
 +              if (errno == EACCES)
 +                      return error("insufficient permission for adding an object to repository database %s", get_object_directory());
 +              else
 +                      return error_errno("unable to create temporary file");
 +      }
 +
 +      /* Set it up */
 +      git_deflate_init(&stream, zlib_compression_level);
 +      stream.next_out = compressed;
 +      stream.avail_out = sizeof(compressed);
 +      the_hash_algo->init_fn(&c);
 +
 +      /* First header.. */
 +      stream.next_in = (unsigned char *)hdr;
 +      stream.avail_in = hdrlen;
 +      while (git_deflate(&stream, 0) == Z_OK)
 +              ; /* nothing */
 +      the_hash_algo->update_fn(&c, hdr, hdrlen);
 +
 +      /* Then the data itself.. */
 +      stream.next_in = (void *)buf;
 +      stream.avail_in = len;
 +      do {
 +              unsigned char *in0 = stream.next_in;
 +              ret = git_deflate(&stream, Z_FINISH);
 +              the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
 +              if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
 +                      die("unable to write sha1 file");
 +              stream.next_out = compressed;
 +              stream.avail_out = sizeof(compressed);
 +      } while (ret == Z_OK);
 +
 +      if (ret != Z_STREAM_END)
 +              die("unable to deflate new object %s (%d)", oid_to_hex(oid),
 +                  ret);
 +      ret = git_deflate_end_gently(&stream);
 +      if (ret != Z_OK)
 +              die("deflateEnd on object %s failed (%d)", oid_to_hex(oid),
 +                  ret);
 +      the_hash_algo->final_fn(parano_oid.hash, &c);
 +      if (oidcmp(oid, &parano_oid) != 0)
 +              die("confused by unstable object source data for %s",
 +                  oid_to_hex(oid));
 +
 +      close_sha1_file(fd);
 +
 +      if (mtime) {
 +              struct utimbuf utb;
 +              utb.actime = mtime;
 +              utb.modtime = mtime;
 +              if (utime(tmp_file.buf, &utb) < 0)
 +                      warning_errno("failed utime() on %s", tmp_file.buf);
 +      }
 +
 +      return finalize_object_file(tmp_file.buf, filename.buf);
 +}
 +
 +static int freshen_loose_object(const struct object_id *oid)
 +{
 +      return check_and_freshen(oid, 1);
 +}
 +
 +static int freshen_packed_object(const struct object_id *oid)
 +{
 +      struct pack_entry e;
 +      if (!find_pack_entry(the_repository, oid, &e))
 +              return 0;
 +      if (e.p->freshened)
 +              return 1;
 +      if (!freshen_file(e.p->pack_name))
 +              return 0;
 +      e.p->freshened = 1;
 +      return 1;
 +}
 +
 +int write_object_file(const void *buf, unsigned long len, const char *type,
 +                    struct object_id *oid)
 +{
 +      char hdr[MAX_HEADER_LEN];
 +      int hdrlen = sizeof(hdr);
 +
 +      /* Normally if we have it in the pack then we do not bother writing
 +       * it out into .git/objects/??/?{38} file.
 +       */
 +      write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
 +      if (freshen_packed_object(oid) || freshen_loose_object(oid))
 +              return 0;
 +      return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
 +}
 +
 +int hash_object_file_literally(const void *buf, unsigned long len,
 +                             const char *type, struct object_id *oid,
 +                             unsigned flags)
 +{
 +      char *header;
 +      int hdrlen, status = 0;
 +
 +      /* type string, SP, %lu of the length plus NUL must fit this */
 +      hdrlen = strlen(type) + MAX_HEADER_LEN;
 +      header = xmalloc(hdrlen);
 +      write_object_file_prepare(buf, len, type, oid, header, &hdrlen);
 +
 +      if (!(flags & HASH_WRITE_OBJECT))
 +              goto cleanup;
 +      if (freshen_packed_object(oid) || freshen_loose_object(oid))
 +              goto cleanup;
 +      status = write_loose_object(oid, header, hdrlen, buf, len, 0);
 +
 +cleanup:
 +      free(header);
 +      return status;
 +}
 +
 +int force_object_loose(const struct object_id *oid, time_t mtime)
 +{
 +      void *buf;
 +      unsigned long len;
 +      enum object_type type;
 +      char hdr[MAX_HEADER_LEN];
 +      int hdrlen;
 +      int ret;
 +
 +      if (has_loose_object(oid))
 +              return 0;
 +      buf = read_object(oid->hash, &type, &len);
 +      if (!buf)
 +              return error("cannot read sha1_file for %s", oid_to_hex(oid));
 +      hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(type), len) + 1;
 +      ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
 +      free(buf);
 +
 +      return ret;
 +}
 +
 +int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
 +{
 +      struct object_id oid;
 +      if (!startup_info->have_repository)
 +              return 0;
 +      hashcpy(oid.hash, sha1);
 +      return oid_object_info_extended(the_repository, &oid, NULL,
 +                                      flags | OBJECT_INFO_SKIP_CACHED) >= 0;
 +}
 +
 +int has_object_file(const struct object_id *oid)
 +{
 +      return has_sha1_file(oid->hash);
 +}
 +
 +int has_object_file_with_flags(const struct object_id *oid, int flags)
 +{
 +      return has_sha1_file_with_flags(oid->hash, flags);
 +}
 +
 +static void check_tree(const void *buf, size_t size)
 +{
 +      struct tree_desc desc;
 +      struct name_entry entry;
 +
 +      init_tree_desc(&desc, buf, size);
 +      while (tree_entry(&desc, &entry))
 +              /* do nothing
 +               * tree_entry() will die() on malformed entries */
 +              ;
 +}
 +
 +static void check_commit(const void *buf, size_t size)
 +{
 +      struct commit c;
 +      memset(&c, 0, sizeof(c));
++      if (parse_commit_buffer(&c, buf, size, 0))
 +              die("corrupt commit");
 +}
 +
 +static void check_tag(const void *buf, size_t size)
 +{
 +      struct tag t;
 +      memset(&t, 0, sizeof(t));
 +      if (parse_tag_buffer(&t, buf, size))
 +              die("corrupt tag");
 +}
 +
 +static int index_mem(struct object_id *oid, void *buf, size_t size,
 +                   enum object_type type,
 +                   const char *path, unsigned flags)
 +{
 +      int ret, re_allocated = 0;
 +      int write_object = flags & HASH_WRITE_OBJECT;
 +
 +      if (!type)
 +              type = OBJ_BLOB;
 +
 +      /*
 +       * Convert blobs to git internal format
 +       */
 +      if ((type == OBJ_BLOB) && path) {
 +              struct strbuf nbuf = STRBUF_INIT;
 +              if (convert_to_git(&the_index, path, buf, size, &nbuf,
 +                                 get_conv_flags(flags))) {
 +                      buf = strbuf_detach(&nbuf, &size);
 +                      re_allocated = 1;
 +              }
 +      }
 +      if (flags & HASH_FORMAT_CHECK) {
 +              if (type == OBJ_TREE)
 +                      check_tree(buf, size);
 +              if (type == OBJ_COMMIT)
 +                      check_commit(buf, size);
 +              if (type == OBJ_TAG)
 +                      check_tag(buf, size);
 +      }
 +
 +      if (write_object)
 +              ret = write_object_file(buf, size, type_name(type), oid);
 +      else
 +              ret = hash_object_file(buf, size, type_name(type), oid);
 +      if (re_allocated)
 +              free(buf);
 +      return ret;
 +}
 +
 +static int index_stream_convert_blob(struct object_id *oid, int fd,
 +                                   const char *path, unsigned flags)
 +{
 +      int ret;
 +      const int write_object = flags & HASH_WRITE_OBJECT;
 +      struct strbuf sbuf = STRBUF_INIT;
 +
 +      assert(path);
 +      assert(would_convert_to_git_filter_fd(path));
 +
 +      convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
 +                               get_conv_flags(flags));
 +
 +      if (write_object)
 +              ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
 +                                      oid);
 +      else
 +              ret = hash_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
 +                                     oid);
 +      strbuf_release(&sbuf);
 +      return ret;
 +}
 +
 +static int index_pipe(struct object_id *oid, int fd, enum object_type type,
 +                    const char *path, unsigned flags)
 +{
 +      struct strbuf sbuf = STRBUF_INIT;
 +      int ret;
 +
 +      if (strbuf_read(&sbuf, fd, 4096) >= 0)
 +              ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
 +      else
 +              ret = -1;
 +      strbuf_release(&sbuf);
 +      return ret;
 +}
 +
 +#define SMALL_FILE_SIZE (32*1024)
 +
 +static int index_core(struct object_id *oid, int fd, size_t size,
 +                    enum object_type type, const char *path,
 +                    unsigned flags)
 +{
 +      int ret;
 +
 +      if (!size) {
 +              ret = index_mem(oid, "", size, type, path, flags);
 +      } else if (size <= SMALL_FILE_SIZE) {
 +              char *buf = xmalloc(size);
 +              ssize_t read_result = read_in_full(fd, buf, size);
 +              if (read_result < 0)
 +                      ret = error_errno("read error while indexing %s",
 +                                        path ? path : "<unknown>");
 +              else if (read_result != size)
 +                      ret = error("short read while indexing %s",
 +                                  path ? path : "<unknown>");
 +              else
 +                      ret = index_mem(oid, buf, size, type, path, flags);
 +              free(buf);
 +      } else {
 +              void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 +              ret = index_mem(oid, buf, size, type, path, flags);
 +              munmap(buf, size);
 +      }
 +      return ret;
 +}
 +
 +/*
 + * This creates one packfile per large blob unless bulk-checkin
 + * machinery is "plugged".
 + *
 + * This also bypasses the usual "convert-to-git" dance, and that is on
 + * purpose. We could write a streaming version of the converting
 + * functions and insert that before feeding the data to fast-import
 + * (or equivalent in-core API described above). However, that is
 + * somewhat complicated, as we do not know the size of the filter
 + * result, which we need to know beforehand when writing a git object.
 + * Since the primary motivation for trying to stream from the working
 + * tree file and to avoid mmaping it in core is to deal with large
 + * binary blobs, they generally do not want to get any conversion, and
 + * callers should avoid this code path when filters are requested.
 + */
 +static int index_stream(struct object_id *oid, int fd, size_t size,
 +                      enum object_type type, const char *path,
 +                      unsigned flags)
 +{
 +      return index_bulk_checkin(oid, fd, size, type, path, flags);
 +}
 +
 +int index_fd(struct object_id *oid, int fd, struct stat *st,
 +           enum object_type type, const char *path, unsigned flags)
 +{
 +      int ret;
 +
 +      /*
 +       * Call xsize_t() only when needed to avoid potentially unnecessary
 +       * die() for large files.
 +       */
 +      if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
 +              ret = index_stream_convert_blob(oid, fd, path, flags);
 +      else if (!S_ISREG(st->st_mode))
 +              ret = index_pipe(oid, fd, type, path, flags);
 +      else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
 +               (path && would_convert_to_git(&the_index, path)))
 +              ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
 +                               flags);
 +      else
 +              ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
 +                                 flags);
 +      close(fd);
 +      return ret;
 +}
 +
 +int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
 +{
 +      int fd;
 +      struct strbuf sb = STRBUF_INIT;
 +      int rc = 0;
 +
 +      switch (st->st_mode & S_IFMT) {
 +      case S_IFREG:
 +              fd = open(path, O_RDONLY);
 +              if (fd < 0)
 +                      return error_errno("open(\"%s\")", path);
 +              if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
 +                      return error("%s: failed to insert into database",
 +                                   path);
 +              break;
 +      case S_IFLNK:
 +              if (strbuf_readlink(&sb, path, st->st_size))
 +                      return error_errno("readlink(\"%s\")", path);
 +              if (!(flags & HASH_WRITE_OBJECT))
 +                      hash_object_file(sb.buf, sb.len, blob_type, oid);
 +              else if (write_object_file(sb.buf, sb.len, blob_type, oid))
 +                      rc = error("%s: failed to insert into database", path);
 +              strbuf_release(&sb);
 +              break;
 +      case S_IFDIR:
 +              return resolve_gitlink_ref(path, "HEAD", oid);
 +      default:
 +              return error("%s: unsupported file type", path);
 +      }
 +      return rc;
 +}
 +
 +int read_pack_header(int fd, struct pack_header *header)
 +{
 +      if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
 +              /* "eof before pack header was fully read" */
 +              return PH_ERROR_EOF;
 +
 +      if (header->hdr_signature != htonl(PACK_SIGNATURE))
 +              /* "protocol error (pack signature mismatch detected)" */
 +              return PH_ERROR_PACK_SIGNATURE;
 +      if (!pack_version_ok(header->hdr_version))
 +              /* "protocol error (pack version unsupported)" */
 +              return PH_ERROR_PROTOCOL;
 +      return 0;
 +}
 +
 +void assert_oid_type(const struct object_id *oid, enum object_type expect)
 +{
 +      enum object_type type = oid_object_info(the_repository, oid, NULL);
 +      if (type < 0)
 +              die("%s is not a valid object", oid_to_hex(oid));
 +      if (type != expect)
 +              die("%s is not a valid '%s' object", oid_to_hex(oid),
 +                  type_name(expect));
 +}
 +
 +int for_each_file_in_obj_subdir(unsigned int subdir_nr,
 +                              struct strbuf *path,
 +                              each_loose_object_fn obj_cb,
 +                              each_loose_cruft_fn cruft_cb,
 +                              each_loose_subdir_fn subdir_cb,
 +                              void *data)
 +{
 +      size_t origlen, baselen;
 +      DIR *dir;
 +      struct dirent *de;
 +      int r = 0;
 +      struct object_id oid;
 +
 +      if (subdir_nr > 0xff)
 +              BUG("invalid loose object subdirectory: %x", subdir_nr);
 +
 +      origlen = path->len;
 +      strbuf_complete(path, '/');
 +      strbuf_addf(path, "%02x", subdir_nr);
 +
 +      dir = opendir(path->buf);
 +      if (!dir) {
 +              if (errno != ENOENT)
 +                      r = error_errno("unable to open %s", path->buf);
 +              strbuf_setlen(path, origlen);
 +              return r;
 +      }
 +
 +      oid.hash[0] = subdir_nr;
 +      strbuf_addch(path, '/');
 +      baselen = path->len;
 +
 +      while ((de = readdir(dir))) {
 +              size_t namelen;
 +              if (is_dot_or_dotdot(de->d_name))
 +                      continue;
 +
 +              namelen = strlen(de->d_name);
 +              strbuf_setlen(path, baselen);
 +              strbuf_add(path, de->d_name, namelen);
 +              if (namelen == GIT_SHA1_HEXSZ - 2 &&
 +                  !hex_to_bytes(oid.hash + 1, de->d_name,
 +                                GIT_SHA1_RAWSZ - 1)) {
 +                      if (obj_cb) {
 +                              r = obj_cb(&oid, path->buf, data);
 +                              if (r)
 +                                      break;
 +                      }
 +                      continue;
 +              }
 +
 +              if (cruft_cb) {
 +                      r = cruft_cb(de->d_name, path->buf, data);
 +                      if (r)
 +                              break;
 +              }
 +      }
 +      closedir(dir);
 +
 +      strbuf_setlen(path, baselen - 1);
 +      if (!r && subdir_cb)
 +              r = subdir_cb(subdir_nr, path->buf, data);
 +
 +      strbuf_setlen(path, origlen);
 +
 +      return r;
 +}
 +
 +int for_each_loose_file_in_objdir_buf(struct strbuf *path,
 +                          each_loose_object_fn obj_cb,
 +                          each_loose_cruft_fn cruft_cb,
 +                          each_loose_subdir_fn subdir_cb,
 +                          void *data)
 +{
 +      int r = 0;
 +      int i;
 +
 +      for (i = 0; i < 256; i++) {
 +              r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
 +                                              subdir_cb, data);
 +              if (r)
 +                      break;
 +      }
 +
 +      return r;
 +}
 +
 +int for_each_loose_file_in_objdir(const char *path,
 +                                each_loose_object_fn obj_cb,
 +                                each_loose_cruft_fn cruft_cb,
 +                                each_loose_subdir_fn subdir_cb,
 +                                void *data)
 +{
 +      struct strbuf buf = STRBUF_INIT;
 +      int r;
 +
 +      strbuf_addstr(&buf, path);
 +      r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
 +                                            subdir_cb, data);
 +      strbuf_release(&buf);
 +
 +      return r;
 +}
 +
 +struct loose_alt_odb_data {
 +      each_loose_object_fn *cb;
 +      void *data;
 +};
 +
 +static int loose_from_alt_odb(struct alternate_object_database *alt,
 +                            void *vdata)
 +{
 +      struct loose_alt_odb_data *data = vdata;
 +      struct strbuf buf = STRBUF_INIT;
 +      int r;
 +
 +      strbuf_addstr(&buf, alt->path);
 +      r = for_each_loose_file_in_objdir_buf(&buf,
 +                                            data->cb, NULL, NULL,
 +                                            data->data);
 +      strbuf_release(&buf);
 +      return r;
 +}
 +
 +int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
 +{
 +      struct loose_alt_odb_data alt;
 +      int r;
 +
 +      r = for_each_loose_file_in_objdir(get_object_directory(),
 +                                        cb, NULL, NULL, data);
 +      if (r)
 +              return r;
 +
 +      if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
 +              return 0;
 +
 +      alt.cb = cb;
 +      alt.data = data;
 +      return foreach_alt_odb(loose_from_alt_odb, &alt);
 +}
 +
 +static int check_stream_sha1(git_zstream *stream,
 +                           const char *hdr,
 +                           unsigned long size,
 +                           const char *path,
 +                           const unsigned char *expected_sha1)
 +{
 +      git_hash_ctx c;
 +      unsigned char real_sha1[GIT_MAX_RAWSZ];
 +      unsigned char buf[4096];
 +      unsigned long total_read;
 +      int status = Z_OK;
 +
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, hdr, stream->total_out);
 +
 +      /*
 +       * We already read some bytes into hdr, but the ones up to the NUL
 +       * do not count against the object's content size.
 +       */
 +      total_read = stream->total_out - strlen(hdr) - 1;
 +
 +      /*
 +       * This size comparison must be "<=" to read the final zlib packets;
 +       * see the comment in unpack_sha1_rest for details.
 +       */
 +      while (total_read <= size &&
 +             (status == Z_OK || status == Z_BUF_ERROR)) {
 +              stream->next_out = buf;
 +              stream->avail_out = sizeof(buf);
 +              if (size - total_read < stream->avail_out)
 +                      stream->avail_out = size - total_read;
 +              status = git_inflate(stream, Z_FINISH);
 +              the_hash_algo->update_fn(&c, buf, stream->next_out - buf);
 +              total_read += stream->next_out - buf;
 +      }
 +      git_inflate_end(stream);
 +
 +      if (status != Z_STREAM_END) {
 +              error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
 +              return -1;
 +      }
 +      if (stream->avail_in) {
 +              error("garbage at end of loose object '%s'",
 +                    sha1_to_hex(expected_sha1));
 +              return -1;
 +      }
 +
 +      the_hash_algo->final_fn(real_sha1, &c);
 +      if (hashcmp(expected_sha1, real_sha1)) {
 +              error("sha1 mismatch for %s (expected %s)", path,
 +                    sha1_to_hex(expected_sha1));
 +              return -1;
 +      }
 +
 +      return 0;
 +}
 +
 +int read_loose_object(const char *path,
 +                    const struct object_id *expected_oid,
 +                    enum object_type *type,
 +                    unsigned long *size,
 +                    void **contents)
 +{
 +      int ret = -1;
 +      void *map = NULL;
 +      unsigned long mapsize;
 +      git_zstream stream;
 +      char hdr[MAX_HEADER_LEN];
 +
 +      *contents = NULL;
 +
 +      map = map_sha1_file_1(the_repository, path, NULL, &mapsize);
 +      if (!map) {
 +              error_errno("unable to mmap %s", path);
 +              goto out;
 +      }
 +
 +      if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
 +              error("unable to unpack header of %s", path);
 +              goto out;
 +      }
 +
 +      *type = parse_sha1_header(hdr, size);
 +      if (*type < 0) {
 +              error("unable to parse header of %s", path);
 +              git_inflate_end(&stream);
 +              goto out;
 +      }
 +
 +      if (*type == OBJ_BLOB && *size > big_file_threshold) {
 +              if (check_stream_sha1(&stream, hdr, *size, path, expected_oid->hash) < 0)
 +                      goto out;
 +      } else {
 +              *contents = unpack_sha1_rest(&stream, hdr, *size, expected_oid->hash);
 +              if (!*contents) {
 +                      error("unable to unpack contents of %s", path);
 +                      git_inflate_end(&stream);
 +                      goto out;
 +              }
 +              if (check_object_signature(expected_oid, *contents,
 +                                       *size, type_name(*type))) {
 +                      error("sha1 mismatch for %s (expected %s)", path,
 +                            oid_to_hex(expected_oid));
 +                      free(*contents);
 +                      goto out;
 +              }
 +      }
 +
 +      ret = 0; /* everything checks out */
 +
 +out:
 +      if (map)
 +              munmap(map, mapsize);
 +      return ret;
 +}