dir: add remove_untracked_cache()
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index 480de9ac92bbc7b48202ca3dd1029ab16a19b739..e2d34b253e4c9c4efcb30e88d11ccd3ce9e14deb 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1,17 +1,13 @@
+/*
+ * The backend-independent part of the reference module.
+ */
+
 #include "cache.h"
 #include "lockfile.h"
 #include "refs.h"
+#include "refs/refs-internal.h"
 #include "object.h"
 #include "tag.h"
-#include "dir.h"
-#include "string-list.h"
-
-struct ref_lock {
-       char *ref_name;
-       char *orig_ref_name;
-       struct lock_file *lk;
-       struct object_id old_oid;
-};
 
 /*
  * How to handle various characters in refnames:
@@ -34,41 +30,6 @@ static unsigned char refname_disposition[256] = {
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
 };
 
-/*
- * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
- * refs (i.e., because the reference is about to be deleted anyway).
- */
-#define REF_DELETING   0x02
-
-/*
- * Used as a flag in ref_update::flags when a loose ref is being
- * pruned.
- */
-#define REF_ISPRUNING  0x04
-
-/*
- * Used as a flag in ref_update::flags when the reference should be
- * updated to new_sha1.
- */
-#define REF_HAVE_NEW   0x08
-
-/*
- * Used as a flag in ref_update::flags when old_sha1 should be
- * checked.
- */
-#define REF_HAVE_OLD   0x10
-
-/*
- * Used as a flag in ref_update::flags when the lockfile needs to be
- * committed.
- */
-#define REF_NEEDS_COMMIT 0x20
-
-/*
- * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
- * value to ref_update::flags
- */
-
 /*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
@@ -157,199 +118,7 @@ int check_refname_format(const char *refname, int flags)
        return 0;
 }
 
-struct ref_entry;
-
-/*
- * Information used (along with the information in ref_entry) to
- * describe a single cached reference.  This data structure only
- * occurs embedded in a union in struct ref_entry, and only when
- * (ref_entry->flag & REF_DIR) is zero.
- */
-struct ref_value {
-       /*
-        * The name of the object to which this reference resolves
-        * (which may be a tag object).  If REF_ISBROKEN, this is
-        * null.  If REF_ISSYMREF, then this is the name of the object
-        * referred to by the last reference in the symlink chain.
-        */
-       struct object_id oid;
-
-       /*
-        * If REF_KNOWS_PEELED, then this field holds the peeled value
-        * of this reference, or null if the reference is known not to
-        * be peelable.  See the documentation for peel_ref() for an
-        * exact definition of "peelable".
-        */
-       struct object_id peeled;
-};
-
-struct ref_cache;
-
-/*
- * Information used (along with the information in ref_entry) to
- * describe a level in the hierarchy of references.  This data
- * structure only occurs embedded in a union in struct ref_entry, and
- * only when (ref_entry.flag & REF_DIR) is set.  In that case,
- * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
- * in the directory have already been read:
- *
- *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
- *         or packed references, already read.
- *
- *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
- *         references that hasn't been read yet (nor has any of its
- *         subdirectories).
- *
- * Entries within a directory are stored within a growable array of
- * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
- * sorted are sorted by their component name in strcmp() order and the
- * remaining entries are unsorted.
- *
- * Loose references are read lazily, one directory at a time.  When a
- * directory of loose references is read, then all of the references
- * in that directory are stored, and REF_INCOMPLETE stubs are created
- * for any subdirectories, but the subdirectories themselves are not
- * read.  The reading is triggered by get_ref_dir().
- */
-struct ref_dir {
-       int nr, alloc;
-
-       /*
-        * Entries with index 0 <= i < sorted are sorted by name.  New
-        * entries are appended to the list unsorted, and are sorted
-        * only when required; thus we avoid the need to sort the list
-        * after the addition of every reference.
-        */
-       int sorted;
-
-       /* A pointer to the ref_cache that contains this ref_dir. */
-       struct ref_cache *ref_cache;
-
-       struct ref_entry **entries;
-};
-
-/*
- * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
- * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
- * public values; see refs.h.
- */
-
-/*
- * The field ref_entry->u.value.peeled of this value entry contains
- * the correct peeled value for the reference, which might be
- * null_sha1 if the reference is not a tag or if it is broken.
- */
-#define REF_KNOWS_PEELED 0x10
-
-/* ref_entry represents a directory of references */
-#define REF_DIR 0x20
-
-/*
- * Entry has not yet been read from disk (used only for REF_DIR
- * entries representing loose references)
- */
-#define REF_INCOMPLETE 0x40
-
-/*
- * A ref_entry represents either a reference or a "subdirectory" of
- * references.
- *
- * Each directory in the reference namespace is represented by a
- * ref_entry with (flags & REF_DIR) set and containing a subdir member
- * that holds the entries in that directory that have been read so
- * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
- * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
- * used for loose reference directories.
- *
- * References are represented by a ref_entry with (flags & REF_DIR)
- * unset and a value member that describes the reference's value.  The
- * flag member is at the ref_entry level, but it is also needed to
- * interpret the contents of the value field (in other words, a
- * ref_value object is not very much use without the enclosing
- * ref_entry).
- *
- * Reference names cannot end with slash and directories' names are
- * always stored with a trailing slash (except for the top-level
- * directory, which is always denoted by "").  This has two nice
- * consequences: (1) when the entries in each subdir are sorted
- * lexicographically by name (as they usually are), the references in
- * a whole tree can be generated in lexicographic order by traversing
- * the tree in left-to-right, depth-first order; (2) the names of
- * references and subdirectories cannot conflict, and therefore the
- * presence of an empty subdirectory does not block the creation of a
- * similarly-named reference.  (The fact that reference names with the
- * same leading components can conflict *with each other* is a
- * separate issue that is regulated by verify_refname_available().)
- *
- * Please note that the name field contains the fully-qualified
- * reference (or subdirectory) name.  Space could be saved by only
- * storing the relative names.  But that would require the full names
- * to be generated on the fly when iterating in do_for_each_ref(), and
- * would break callback functions, who have always been able to assume
- * that the name strings that they are passed will not be freed during
- * the iteration.
- */
-struct ref_entry {
-       unsigned char flag; /* ISSYMREF? ISPACKED? */
-       union {
-               struct ref_value value; /* if not (flags&REF_DIR) */
-               struct ref_dir subdir; /* if (flags&REF_DIR) */
-       } u;
-       /*
-        * The full name of the reference (e.g., "refs/heads/master")
-        * or the full name of the directory with a trailing slash
-        * (e.g., "refs/heads/"):
-        */
-       char name[FLEX_ARRAY];
-};
-
-static void read_loose_refs(const char *dirname, struct ref_dir *dir);
-static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
-static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
-                                         const char *dirname, size_t len,
-                                         int incomplete);
-static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
-
-static struct ref_dir *get_ref_dir(struct ref_entry *entry)
-{
-       struct ref_dir *dir;
-       assert(entry->flag & REF_DIR);
-       dir = &entry->u.subdir;
-       if (entry->flag & REF_INCOMPLETE) {
-               read_loose_refs(entry->name, dir);
-
-               /*
-                * Manually add refs/bisect, which, being
-                * per-worktree, might not appear in the directory
-                * listing for refs/ in the main repo.
-                */
-               if (!strcmp(entry->name, "refs/")) {
-                       int pos = search_ref_dir(dir, "refs/bisect/", 12);
-                       if (pos < 0) {
-                               struct ref_entry *child_entry;
-                               child_entry = create_dir_entry(dir->ref_cache,
-                                                              "refs/bisect/",
-                                                              12, 1);
-                               add_entry_to_dir(dir, child_entry);
-                               read_loose_refs("refs/bisect",
-                                               &child_entry->u.subdir);
-                       }
-               }
-               entry->flag &= ~REF_INCOMPLETE;
-       }
-       return dir;
-}
-
-/*
- * Check if a refname is safe.
- * For refs that start with "refs/" we consider it safe as long they do
- * not try to resolve to outside of refs/.
- *
- * For all other refs we only consider them safe iff they only contain
- * upper case characters and '_' (like "HEAD" AND "MERGE_HEAD", and not like
- * "config").
- */
-static int refname_is_safe(const char *refname)
+int refname_is_safe(const char *refname)
 {
        if (starts_with(refname, "refs/")) {
                char *buf;
@@ -373,3248 +142,480 @@ static int refname_is_safe(const char *refname)
        return 1;
 }
 
-static struct ref_entry *create_ref_entry(const char *refname,
-                                         const unsigned char *sha1, int flag,
-                                         int check_name)
+char *resolve_refdup(const char *refname, int resolve_flags,
+                    unsigned char *sha1, int *flags)
 {
-       int len;
-       struct ref_entry *ref;
-
-       if (check_name &&
-           check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
-               die("Reference has invalid format: '%s'", refname);
-       len = strlen(refname) + 1;
-       ref = xmalloc(sizeof(struct ref_entry) + len);
-       hashcpy(ref->u.value.oid.hash, sha1);
-       oidclr(&ref->u.value.peeled);
-       memcpy(ref->name, refname, len);
-       ref->flag = flag;
-       return ref;
+       return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
+                                                 sha1, flags));
 }
 
-static void clear_ref_dir(struct ref_dir *dir);
+/* The argument to filter_refs */
+struct ref_filter {
+       const char *pattern;
+       each_ref_fn *fn;
+       void *cb_data;
+};
 
-static void free_ref_entry(struct ref_entry *entry)
+int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 {
-       if (entry->flag & REF_DIR) {
-               /*
-                * Do not use get_ref_dir() here, as that might
-                * trigger the reading of loose refs.
-                */
-               clear_ref_dir(&entry->u.subdir);
-       }
-       free(entry);
+       if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
+               return 0;
+       return -1;
 }
 
-/*
- * Add a ref_entry to the end of dir (unsorted).  Entry is always
- * stored directly in dir; no recursion into subdirectories is
- * done.
- */
-static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
+int read_ref(const char *refname, unsigned char *sha1)
 {
-       ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
-       dir->entries[dir->nr++] = entry;
-       /* optimize for the case that entries are added in order */
-       if (dir->nr == 1 ||
-           (dir->nr == dir->sorted + 1 &&
-            strcmp(dir->entries[dir->nr - 2]->name,
-                   dir->entries[dir->nr - 1]->name) < 0))
-               dir->sorted = dir->nr;
+       return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 }
 
-/*
- * Clear and free all entries in dir, recursively.
- */
-static void clear_ref_dir(struct ref_dir *dir)
+int ref_exists(const char *refname)
 {
-       int i;
-       for (i = 0; i < dir->nr; i++)
-               free_ref_entry(dir->entries[i]);
-       free(dir->entries);
-       dir->sorted = dir->nr = dir->alloc = 0;
-       dir->entries = NULL;
+       unsigned char sha1[20];
+       return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 }
 
-/*
- * Create a struct ref_entry object for the specified dirname.
- * dirname is the name of the directory with a trailing slash (e.g.,
- * "refs/heads/") or "" for the top-level directory.
- */
-static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
-                                         const char *dirname, size_t len,
-                                         int incomplete)
+static int filter_refs(const char *refname, const struct object_id *oid,
+                          int flags, void *data)
 {
-       struct ref_entry *direntry;
-       direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
-       memcpy(direntry->name, dirname, len);
-       direntry->name[len] = '\0';
-       direntry->u.subdir.ref_cache = ref_cache;
-       direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
-       return direntry;
+       struct ref_filter *filter = (struct ref_filter *)data;
+
+       if (wildmatch(filter->pattern, refname, 0, NULL))
+               return 0;
+       return filter->fn(refname, oid, flags, filter->cb_data);
 }
 
-static int ref_entry_cmp(const void *a, const void *b)
+enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 {
-       struct ref_entry *one = *(struct ref_entry **)a;
-       struct ref_entry *two = *(struct ref_entry **)b;
-       return strcmp(one->name, two->name);
-}
+       struct object *o = lookup_unknown_object(name);
 
-static void sort_ref_dir(struct ref_dir *dir);
+       if (o->type == OBJ_NONE) {
+               int type = sha1_object_info(name, NULL);
+               if (type < 0 || !object_as_type(o, type, 0))
+                       return PEEL_INVALID;
+       }
 
-struct string_slice {
-       size_t len;
-       const char *str;
-};
+       if (o->type != OBJ_TAG)
+               return PEEL_NON_TAG;
 
-static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
-{
-       const struct string_slice *key = key_;
-       const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
-       int cmp = strncmp(key->str, ent->name, key->len);
-       if (cmp)
-               return cmp;
-       return '\0' - (unsigned char)ent->name[key->len];
+       o = deref_tag_noverify(o);
+       if (!o)
+               return PEEL_INVALID;
+
+       hashcpy(sha1, o->oid.hash);
+       return PEEL_PEELED;
 }
 
-/*
- * Return the index of the entry with the given refname from the
- * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
- * no such entry is found.  dir must already be complete.
- */
-static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
-{
-       struct ref_entry **r;
-       struct string_slice key;
+struct warn_if_dangling_data {
+       FILE *fp;
+       const char *refname;
+       const struct string_list *refnames;
+       const char *msg_fmt;
+};
 
-       if (refname == NULL || !dir->nr)
-               return -1;
+static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
+                                  int flags, void *cb_data)
+{
+       struct warn_if_dangling_data *d = cb_data;
+       const char *resolves_to;
+       struct object_id junk;
 
-       sort_ref_dir(dir);
-       key.len = len;
-       key.str = refname;
-       r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
-                   ref_entry_cmp_sslice);
+       if (!(flags & REF_ISSYMREF))
+               return 0;
 
-       if (r == NULL)
-               return -1;
+       resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
+       if (!resolves_to
+           || (d->refname
+               ? strcmp(resolves_to, d->refname)
+               : !string_list_has_string(d->refnames, resolves_to))) {
+               return 0;
+       }
 
-       return r - dir->entries;
+       fprintf(d->fp, d->msg_fmt, refname);
+       fputc('\n', d->fp);
+       return 0;
 }
 
-/*
- * Search for a directory entry directly within dir (without
- * recursing).  Sort dir if necessary.  subdirname must be a directory
- * name (i.e., end in '/').  If mkdir is set, then create the
- * directory if it is missing; otherwise, return NULL if the desired
- * directory cannot be found.  dir must already be complete.
- */
-static struct ref_dir *search_for_subdir(struct ref_dir *dir,
-                                        const char *subdirname, size_t len,
-                                        int mkdir)
+void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 {
-       int entry_index = search_ref_dir(dir, subdirname, len);
-       struct ref_entry *entry;
-       if (entry_index == -1) {
-               if (!mkdir)
-                       return NULL;
-               /*
-                * Since dir is complete, the absence of a subdir
-                * means that the subdir really doesn't exist;
-                * therefore, create an empty record for it but mark
-                * the record complete.
-                */
-               entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
-               add_entry_to_dir(dir, entry);
-       } else {
-               entry = dir->entries[entry_index];
-       }
-       return get_ref_dir(entry);
+       struct warn_if_dangling_data data;
+
+       data.fp = fp;
+       data.refname = refname;
+       data.refnames = NULL;
+       data.msg_fmt = msg_fmt;
+       for_each_rawref(warn_if_dangling_symref, &data);
 }
 
-/*
- * If refname is a reference name, find the ref_dir within the dir
- * tree that should hold refname.  If refname is a directory name
- * (i.e., ends in '/'), then return that ref_dir itself.  dir must
- * represent the top-level directory and must already be complete.
- * Sort ref_dirs and recurse into subdirectories as necessary.  If
- * mkdir is set, then create any missing directories; otherwise,
- * return NULL if the desired directory cannot be found.
- */
-static struct ref_dir *find_containing_dir(struct ref_dir *dir,
-                                          const char *refname, int mkdir)
+void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 {
-       const char *slash;
-       for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
-               size_t dirnamelen = slash - refname + 1;
-               struct ref_dir *subdir;
-               subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
-               if (!subdir) {
-                       dir = NULL;
-                       break;
-               }
-               dir = subdir;
-       }
+       struct warn_if_dangling_data data;
 
-       return dir;
+       data.fp = fp;
+       data.refname = NULL;
+       data.refnames = refnames;
+       data.msg_fmt = msg_fmt;
+       for_each_rawref(warn_if_dangling_symref, &data);
 }
 
-/*
- * Find the value entry with the given name in dir, sorting ref_dirs
- * and recursing into subdirectories as necessary.  If the name is not
- * found or it corresponds to a directory entry, return NULL.
- */
-static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
+int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 {
-       int entry_index;
-       struct ref_entry *entry;
-       dir = find_containing_dir(dir, refname, 0);
-       if (!dir)
-               return NULL;
-       entry_index = search_ref_dir(dir, refname, strlen(refname));
-       if (entry_index == -1)
-               return NULL;
-       entry = dir->entries[entry_index];
-       return (entry->flag & REF_DIR) ? NULL : entry;
+       return for_each_ref_in("refs/tags/", fn, cb_data);
 }
 
-/*
- * Remove the entry with the given name from dir, recursing into
- * subdirectories as necessary.  If refname is the name of a directory
- * (i.e., ends with '/'), then remove the directory and its contents.
- * If the removal was successful, return the number of entries
- * remaining in the directory entry that contained the deleted entry.
- * If the name was not found, return -1.  Please note that this
- * function only deletes the entry from the cache; it does not delete
- * it from the filesystem or ensure that other cache entries (which
- * might be symbolic references to the removed entry) are updated.
- * Nor does it remove any containing dir entries that might be made
- * empty by the removal.  dir must represent the top-level directory
- * and must already be complete.
- */
-static int remove_entry(struct ref_dir *dir, const char *refname)
+int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       int refname_len = strlen(refname);
-       int entry_index;
-       struct ref_entry *entry;
-       int is_dir = refname[refname_len - 1] == '/';
-       if (is_dir) {
-               /*
-                * refname represents a reference directory.  Remove
-                * the trailing slash; otherwise we will get the
-                * directory *representing* refname rather than the
-                * one *containing* it.
-                */
-               char *dirname = xmemdupz(refname, refname_len - 1);
-               dir = find_containing_dir(dir, dirname, 0);
-               free(dirname);
-       } else {
-               dir = find_containing_dir(dir, refname, 0);
-       }
-       if (!dir)
-               return -1;
-       entry_index = search_ref_dir(dir, refname, refname_len);
-       if (entry_index == -1)
-               return -1;
-       entry = dir->entries[entry_index];
-
-       memmove(&dir->entries[entry_index],
-               &dir->entries[entry_index + 1],
-               (dir->nr - entry_index - 1) * sizeof(*dir->entries)
-               );
-       dir->nr--;
-       if (dir->sorted > entry_index)
-               dir->sorted--;
-       free_ref_entry(entry);
-       return dir->nr;
+       return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 }
 
-/*
- * Add a ref_entry to the ref_dir (unsorted), recursing into
- * subdirectories as necessary.  dir must represent the top-level
- * directory.  Return 0 on success.
- */
-static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
+int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 {
-       dir = find_containing_dir(dir, ref->name, 1);
-       if (!dir)
-               return -1;
-       add_entry_to_dir(dir, ref);
-       return 0;
+       return for_each_ref_in("refs/heads/", fn, cb_data);
 }
 
-/*
- * Emit a warning and return true iff ref1 and ref2 have the same name
- * and the same sha1.  Die if they have the same name but different
- * sha1s.
- */
-static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
+int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       if (strcmp(ref1->name, ref2->name))
-               return 0;
-
-       /* Duplicate name; make sure that they don't conflict: */
-
-       if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
-               /* This is impossible by construction */
-               die("Reference directory conflict: %s", ref1->name);
-
-       if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
-               die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
-
-       warning("Duplicated ref: %s", ref1->name);
-       return 1;
+       return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 }
 
-/*
- * Sort the entries in dir non-recursively (if they are not already
- * sorted) and remove any duplicate entries.
- */
-static void sort_ref_dir(struct ref_dir *dir)
+int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 {
-       int i, j;
-       struct ref_entry *last = NULL;
-
-       /*
-        * This check also prevents passing a zero-length array to qsort(),
-        * which is a problem on some platforms.
-        */
-       if (dir->sorted == dir->nr)
-               return;
-
-       qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
-
-       /* Remove any duplicates: */
-       for (i = 0, j = 0; j < dir->nr; j++) {
-               struct ref_entry *entry = dir->entries[j];
-               if (last && is_dup_ref(last, entry))
-                       free_ref_entry(entry);
-               else
-                       last = dir->entries[i++] = entry;
-       }
-       dir->sorted = dir->nr = i;
+       return for_each_ref_in("refs/remotes/", fn, cb_data);
 }
 
-/* Include broken references in a do_for_each_ref*() iteration: */
-#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
-
-/*
- * Return true iff the reference described by entry can be resolved to
- * an object in the database.  Emit a warning if the referred-to
- * object does not exist.
- */
-static int ref_resolves_to_object(struct ref_entry *entry)
+int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       if (entry->flag & REF_ISBROKEN)
-               return 0;
-       if (!has_sha1_file(entry->u.value.oid.hash)) {
-               error("%s does not point to a valid object!", entry->name);
-               return 0;
-       }
-       return 1;
+       return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 }
 
-/*
- * current_ref is a performance hack: when iterating over references
- * using the for_each_ref*() functions, current_ref is set to the
- * current reference's entry before calling the callback function.  If
- * the callback function calls peel_ref(), then peel_ref() first
- * checks whether the reference to be peeled is the current reference
- * (it usually is) and if so, returns that reference's peeled version
- * if it is available.  This avoids a refname lookup in a common case.
- */
-static struct ref_entry *current_ref;
+int head_ref_namespaced(each_ref_fn fn, void *cb_data)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int ret = 0;
+       struct object_id oid;
+       int flag;
 
-typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
+       strbuf_addf(&buf, "%sHEAD", get_git_namespace());
+       if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
+               ret = fn(buf.buf, &oid, flag, cb_data);
+       strbuf_release(&buf);
 
-struct ref_entry_cb {
-       const char *base;
-       int trim;
-       int flags;
-       each_ref_fn *fn;
-       void *cb_data;
-};
+       return ret;
+}
 
-/*
- * Handle one reference in a do_for_each_ref*()-style iteration,
- * calling an each_ref_fn for each entry.
- */
-static int do_one_ref(struct ref_entry *entry, void *cb_data)
+int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
+       const char *prefix, void *cb_data)
 {
-       struct ref_entry_cb *data = cb_data;
-       struct ref_entry *old_current_ref;
-       int retval;
+       struct strbuf real_pattern = STRBUF_INIT;
+       struct ref_filter filter;
+       int ret;
 
-       if (!starts_with(entry->name, data->base))
-               return 0;
+       if (!prefix && !starts_with(pattern, "refs/"))
+               strbuf_addstr(&real_pattern, "refs/");
+       else if (prefix)
+               strbuf_addstr(&real_pattern, prefix);
+       strbuf_addstr(&real_pattern, pattern);
 
-       if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
-             !ref_resolves_to_object(entry))
-               return 0;
+       if (!has_glob_specials(pattern)) {
+               /* Append implied '/' '*' if not present. */
+               strbuf_complete(&real_pattern, '/');
+               /* No need to check for '*', there is none. */
+               strbuf_addch(&real_pattern, '*');
+       }
 
-       /* Store the old value, in case this is a recursive call: */
-       old_current_ref = current_ref;
-       current_ref = entry;
-       retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
-                         entry->flag, data->cb_data);
-       current_ref = old_current_ref;
-       return retval;
-}
+       filter.pattern = real_pattern.buf;
+       filter.fn = fn;
+       filter.cb_data = cb_data;
+       ret = for_each_ref(filter_refs, &filter);
 
-/*
- * Call fn for each reference in dir that has index in the range
- * offset <= index < dir->nr.  Recurse into subdirectories that are in
- * that index range, sorting them before iterating.  This function
- * does not sort dir itself; it should be sorted beforehand.  fn is
- * called for all references, including broken ones.
- */
-static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
-                                   each_ref_entry_fn fn, void *cb_data)
-{
-       int i;
-       assert(dir->sorted == dir->nr);
-       for (i = offset; i < dir->nr; i++) {
-               struct ref_entry *entry = dir->entries[i];
-               int retval;
-               if (entry->flag & REF_DIR) {
-                       struct ref_dir *subdir = get_ref_dir(entry);
-                       sort_ref_dir(subdir);
-                       retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
-               } else {
-                       retval = fn(entry, cb_data);
-               }
-               if (retval)
-                       return retval;
-       }
-       return 0;
+       strbuf_release(&real_pattern);
+       return ret;
 }
 
-/*
- * Call fn for each reference in the union of dir1 and dir2, in order
- * by refname.  Recurse into subdirectories.  If a value entry appears
- * in both dir1 and dir2, then only process the version that is in
- * dir2.  The input dirs must already be sorted, but subdirs will be
- * sorted as needed.  fn is called for all references, including
- * broken ones.
- */
-static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
-                                    struct ref_dir *dir2,
-                                    each_ref_entry_fn fn, void *cb_data)
+int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 {
-       int retval;
-       int i1 = 0, i2 = 0;
-
-       assert(dir1->sorted == dir1->nr);
-       assert(dir2->sorted == dir2->nr);
-       while (1) {
-               struct ref_entry *e1, *e2;
-               int cmp;
-               if (i1 == dir1->nr) {
-                       return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
-               }
-               if (i2 == dir2->nr) {
-                       return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
-               }
-               e1 = dir1->entries[i1];
-               e2 = dir2->entries[i2];
-               cmp = strcmp(e1->name, e2->name);
-               if (cmp == 0) {
-                       if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
-                               /* Both are directories; descend them in parallel. */
-                               struct ref_dir *subdir1 = get_ref_dir(e1);
-                               struct ref_dir *subdir2 = get_ref_dir(e2);
-                               sort_ref_dir(subdir1);
-                               sort_ref_dir(subdir2);
-                               retval = do_for_each_entry_in_dirs(
-                                               subdir1, subdir2, fn, cb_data);
-                               i1++;
-                               i2++;
-                       } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
-                               /* Both are references; ignore the one from dir1. */
-                               retval = fn(e2, cb_data);
-                               i1++;
-                               i2++;
-                       } else {
-                               die("conflict between reference and directory: %s",
-                                   e1->name);
-                       }
-               } else {
-                       struct ref_entry *e;
-                       if (cmp < 0) {
-                               e = e1;
-                               i1++;
-                       } else {
-                               e = e2;
-                               i2++;
-                       }
-                       if (e->flag & REF_DIR) {
-                               struct ref_dir *subdir = get_ref_dir(e);
-                               sort_ref_dir(subdir);
-                               retval = do_for_each_entry_in_dir(
-                                               subdir, 0, fn, cb_data);
-                       } else {
-                               retval = fn(e, cb_data);
-                       }
-               }
-               if (retval)
-                       return retval;
-       }
+       return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 }
 
-/*
- * Load all of the refs from the dir into our in-memory cache. The hard work
- * of loading loose refs is done by get_ref_dir(), so we just need to recurse
- * through all of the sub-directories. We do not even need to care about
- * sorting, as traversal order does not matter to us.
- */
-static void prime_ref_dir(struct ref_dir *dir)
+const char *prettify_refname(const char *name)
 {
-       int i;
-       for (i = 0; i < dir->nr; i++) {
-               struct ref_entry *entry = dir->entries[i];
-               if (entry->flag & REF_DIR)
-                       prime_ref_dir(get_ref_dir(entry));
-       }
+       return name + (
+               starts_with(name, "refs/heads/") ? 11 :
+               starts_with(name, "refs/tags/") ? 10 :
+               starts_with(name, "refs/remotes/") ? 13 :
+               0);
 }
 
-struct nonmatching_ref_data {
-       const struct string_list *skip;
-       const char *conflicting_refname;
+static const char *ref_rev_parse_rules[] = {
+       "%.*s",
+       "refs/%.*s",
+       "refs/tags/%.*s",
+       "refs/heads/%.*s",
+       "refs/remotes/%.*s",
+       "refs/remotes/%.*s/HEAD",
+       NULL
 };
 
-static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
+int refname_match(const char *abbrev_name, const char *full_name)
 {
-       struct nonmatching_ref_data *data = vdata;
+       const char **p;
+       const int abbrev_name_len = strlen(abbrev_name);
 
-       if (data->skip && string_list_has_string(data->skip, entry->name))
-               return 0;
+       for (p = ref_rev_parse_rules; *p; p++) {
+               if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
+                       return 1;
+               }
+       }
 
-       data->conflicting_refname = entry->name;
-       return 1;
+       return 0;
 }
 
 /*
- * Return 0 if a reference named refname could be created without
- * conflicting with the name of an existing reference in dir.
- * See verify_refname_available for more information.
+ * *string and *len will only be substituted, and *string returned (for
+ * later free()ing) if the string passed in is a magic short-hand form
+ * to name a branch.
  */
-static int verify_refname_available_dir(const char *refname,
-                                       const struct string_list *extras,
-                                       const struct string_list *skip,
-                                       struct ref_dir *dir,
-                                       struct strbuf *err)
+static char *substitute_branch_name(const char **string, int *len)
 {
-       const char *slash;
-       int pos;
-       struct strbuf dirname = STRBUF_INIT;
-       int ret = -1;
-
-       /*
-        * For the sake of comments in this function, suppose that
-        * refname is "refs/foo/bar".
-        */
+       struct strbuf buf = STRBUF_INIT;
+       int ret = interpret_branch_name(*string, *len, &buf);
 
-       assert(err);
+       if (ret == *len) {
+               size_t size;
+               *string = strbuf_detach(&buf, &size);
+               *len = size;
+               return (char *)*string;
+       }
 
-       strbuf_grow(&dirname, strlen(refname) + 1);
-       for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
-               /* Expand dirname to the new prefix, not including the trailing slash: */
-               strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
+       return NULL;
+}
 
-               /*
-                * We are still at a leading dir of the refname (e.g.,
-                * "refs/foo"; if there is a reference with that name,
-                * it is a conflict, *unless* it is in skip.
-                */
-               if (dir) {
-                       pos = search_ref_dir(dir, dirname.buf, dirname.len);
-                       if (pos >= 0 &&
-                           (!skip || !string_list_has_string(skip, dirname.buf))) {
-                               /*
-                                * We found a reference whose name is
-                                * a proper prefix of refname; e.g.,
-                                * "refs/foo", and is not in skip.
-                                */
-                               strbuf_addf(err, "'%s' exists; cannot create '%s'",
-                                           dirname.buf, refname);
-                               goto cleanup;
-                       }
-               }
+int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
+{
+       char *last_branch = substitute_branch_name(&str, &len);
+       const char **p, *r;
+       int refs_found = 0;
 
-               if (extras && string_list_has_string(extras, dirname.buf) &&
-                   (!skip || !string_list_has_string(skip, dirname.buf))) {
-                       strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
-                                   refname, dirname.buf);
-                       goto cleanup;
-               }
+       *ref = NULL;
+       for (p = ref_rev_parse_rules; *p; p++) {
+               char fullref[PATH_MAX];
+               unsigned char sha1_from_ref[20];
+               unsigned char *this_result;
+               int flag;
 
-               /*
-                * Otherwise, we can try to continue our search with
-                * the next component. So try to look up the
-                * directory, e.g., "refs/foo/". If we come up empty,
-                * we know there is nothing under this whole prefix,
-                * but even in that case we still have to continue the
-                * search for conflicts with extras.
-                */
-               strbuf_addch(&dirname, '/');
-               if (dir) {
-                       pos = search_ref_dir(dir, dirname.buf, dirname.len);
-                       if (pos < 0) {
-                               /*
-                                * There was no directory "refs/foo/",
-                                * so there is nothing under this
-                                * whole prefix. So there is no need
-                                * to continue looking for conflicting
-                                * references. But we need to continue
-                                * looking for conflicting extras.
-                                */
-                               dir = NULL;
-                       } else {
-                               dir = get_ref_dir(dir->entries[pos]);
-                       }
+               this_result = refs_found ? sha1_from_ref : sha1;
+               mksnpath(fullref, sizeof(fullref), *p, len, str);
+               r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
+                                      this_result, &flag);
+               if (r) {
+                       if (!refs_found++)
+                               *ref = xstrdup(r);
+                       if (!warn_ambiguous_refs)
+                               break;
+               } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
+                       warning("ignoring dangling symref %s.", fullref);
+               } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
+                       warning("ignoring broken ref %s.", fullref);
                }
        }
+       free(last_branch);
+       return refs_found;
+}
 
-       /*
-        * We are at the leaf of our refname (e.g., "refs/foo/bar").
-        * There is no point in searching for a reference with that
-        * name, because a refname isn't considered to conflict with
-        * itself. But we still need to check for references whose
-        * names are in the "refs/foo/bar/" namespace, because they
-        * *do* conflict.
-        */
-       strbuf_addstr(&dirname, refname + dirname.len);
-       strbuf_addch(&dirname, '/');
+int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
+{
+       char *last_branch = substitute_branch_name(&str, &len);
+       const char **p;
+       int logs_found = 0;
 
-       if (dir) {
-               pos = search_ref_dir(dir, dirname.buf, dirname.len);
+       *log = NULL;
+       for (p = ref_rev_parse_rules; *p; p++) {
+               unsigned char hash[20];
+               char path[PATH_MAX];
+               const char *ref, *it;
 
-               if (pos >= 0) {
-                       /*
-                        * We found a directory named "$refname/"
-                        * (e.g., "refs/foo/bar/"). It is a problem
-                        * iff it contains any ref that is not in
-                        * "skip".
-                        */
-                       struct nonmatching_ref_data data;
-
-                       data.skip = skip;
-                       data.conflicting_refname = NULL;
-                       dir = get_ref_dir(dir->entries[pos]);
-                       sort_ref_dir(dir);
-                       if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
-                               strbuf_addf(err, "'%s' exists; cannot create '%s'",
-                                           data.conflicting_refname, refname);
-                               goto cleanup;
-                       }
+               mksnpath(path, sizeof(path), *p, len, str);
+               ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
+                                        hash, NULL);
+               if (!ref)
+                       continue;
+               if (reflog_exists(path))
+                       it = path;
+               else if (strcmp(ref, path) && reflog_exists(ref))
+                       it = ref;
+               else
+                       continue;
+               if (!logs_found++) {
+                       *log = xstrdup(it);
+                       hashcpy(sha1, hash);
                }
+               if (!warn_ambiguous_refs)
+                       break;
        }
+       free(last_branch);
+       return logs_found;
+}
 
-       if (extras) {
-               /*
-                * Check for entries in extras that start with
-                * "$refname/". We do that by looking for the place
-                * where "$refname/" would be inserted in extras. If
-                * there is an entry at that position that starts with
-                * "$refname/" and is not in skip, then we have a
-                * conflict.
-                */
-               for (pos = string_list_find_insert_index(extras, dirname.buf, 0);
-                    pos < extras->nr; pos++) {
-                       const char *extra_refname = extras->items[pos].string;
+static int is_per_worktree_ref(const char *refname)
+{
+       return !strcmp(refname, "HEAD") ||
+               starts_with(refname, "refs/bisect/");
+}
 
-                       if (!starts_with(extra_refname, dirname.buf))
-                               break;
+static int is_pseudoref_syntax(const char *refname)
+{
+       const char *c;
 
-                       if (!skip || !string_list_has_string(skip, extra_refname)) {
-                               strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
-                                           refname, extra_refname);
-                               goto cleanup;
-                       }
-               }
+       for (c = refname; *c; c++) {
+               if (!isupper(*c) && *c != '-' && *c != '_')
+                       return 0;
        }
 
-       /* No conflicts were found */
-       ret = 0;
-
-cleanup:
-       strbuf_release(&dirname);
-       return ret;
+       return 1;
 }
 
-struct packed_ref_cache {
-       struct ref_entry *root;
-
-       /*
-        * Count of references to the data structure in this instance,
-        * including the pointer from ref_cache::packed if any.  The
-        * data will not be freed as long as the reference count is
-        * nonzero.
-        */
-       unsigned int referrers;
-
-       /*
-        * Iff the packed-refs file associated with this instance is
-        * currently locked for writing, this points at the associated
-        * lock (which is owned by somebody else).  The referrer count
-        * is also incremented when the file is locked and decremented
-        * when it is unlocked.
-        */
-       struct lock_file *lock;
-
-       /* The metadata from when this packed-refs cache was read */
-       struct stat_validity validity;
-};
-
-/*
- * Future: need to be in "struct repository"
- * when doing a full libification.
- */
-static struct ref_cache {
-       struct ref_cache *next;
-       struct ref_entry *loose;
-       struct packed_ref_cache *packed;
-       /*
-        * The submodule name, or "" for the main repo.  We allocate
-        * length 1 rather than FLEX_ARRAY so that the main ref_cache
-        * is initialized correctly.
-        */
-       char name[1];
-} ref_cache, *submodule_ref_caches;
-
-/* Lock used for the main packed-refs file: */
-static struct lock_file packlock;
-
-/*
- * Increment the reference count of *packed_refs.
- */
-static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
+enum ref_type ref_type(const char *refname)
 {
-       packed_refs->referrers++;
+       if (is_per_worktree_ref(refname))
+               return REF_TYPE_PER_WORKTREE;
+       if (is_pseudoref_syntax(refname))
+               return REF_TYPE_PSEUDOREF;
+       return REF_TYPE_NORMAL;
 }
 
-/*
- * Decrease the reference count of *packed_refs.  If it goes to zero,
- * free *packed_refs and return true; otherwise return false.
- */
-static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
+static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
+                          const unsigned char *old_sha1, struct strbuf *err)
 {
-       if (!--packed_refs->referrers) {
-               free_ref_entry(packed_refs->root);
-               stat_validity_clear(&packed_refs->validity);
-               free(packed_refs);
-               return 1;
-       } else {
-               return 0;
+       const char *filename;
+       int fd;
+       static struct lock_file lock;
+       struct strbuf buf = STRBUF_INIT;
+       int ret = -1;
+
+       strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
+
+       filename = git_path("%s", pseudoref);
+       fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
+       if (fd < 0) {
+               strbuf_addf(err, "Could not open '%s' for writing: %s",
+                           filename, strerror(errno));
+               return -1;
        }
-}
 
-static void clear_packed_ref_cache(struct ref_cache *refs)
-{
-       if (refs->packed) {
-               struct packed_ref_cache *packed_refs = refs->packed;
+       if (old_sha1) {
+               unsigned char actual_old_sha1[20];
 
-               if (packed_refs->lock)
-                       die("internal error: packed-ref cache cleared while locked");
-               refs->packed = NULL;
-               release_packed_ref_cache(packed_refs);
+               if (read_ref(pseudoref, actual_old_sha1))
+                       die("could not read ref '%s'", pseudoref);
+               if (hashcmp(actual_old_sha1, old_sha1)) {
+                       strbuf_addf(err, "Unexpected sha1 when writing %s", pseudoref);
+                       rollback_lock_file(&lock);
+                       goto done;
+               }
        }
-}
 
-static void clear_loose_ref_cache(struct ref_cache *refs)
-{
-       if (refs->loose) {
-               free_ref_entry(refs->loose);
-               refs->loose = NULL;
+       if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
+               strbuf_addf(err, "Could not write to '%s'", filename);
+               rollback_lock_file(&lock);
+               goto done;
        }
-}
 
-static struct ref_cache *create_ref_cache(const char *submodule)
-{
-       int len;
-       struct ref_cache *refs;
-       if (!submodule)
-               submodule = "";
-       len = strlen(submodule) + 1;
-       refs = xcalloc(1, sizeof(struct ref_cache) + len);
-       memcpy(refs->name, submodule, len);
-       return refs;
+       commit_lock_file(&lock);
+       ret = 0;
+done:
+       strbuf_release(&buf);
+       return ret;
 }
 
-/*
- * Return a pointer to a ref_cache for the specified submodule. For
- * the main repository, use submodule==NULL. The returned structure
- * will be allocated and initialized but not necessarily populated; it
- * should not be freed.
- */
-static struct ref_cache *get_ref_cache(const char *submodule)
+static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 {
-       struct ref_cache *refs;
-
-       if (!submodule || !*submodule)
-               return &ref_cache;
+       static struct lock_file lock;
+       const char *filename;
 
-       for (refs = submodule_ref_caches; refs; refs = refs->next)
-               if (!strcmp(submodule, refs->name))
-                       return refs;
+       filename = git_path("%s", pseudoref);
 
-       refs = create_ref_cache(submodule);
-       refs->next = submodule_ref_caches;
-       submodule_ref_caches = refs;
-       return refs;
-}
-
-/* The length of a peeled reference line in packed-refs, including EOL: */
-#define PEELED_LINE_LENGTH 42
-
-/*
- * The packed-refs header line that we write out.  Perhaps other
- * traits will be added later.  The trailing space is required.
- */
-static const char PACKED_REFS_HEADER[] =
-       "# pack-refs with: peeled fully-peeled \n";
-
-/*
- * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
- * Return a pointer to the refname within the line (null-terminated),
- * or NULL if there was a problem.
- */
-static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
-{
-       const char *ref;
-
-       /*
-        * 42: the answer to everything.
-        *
-        * In this case, it happens to be the answer to
-        *  40 (length of sha1 hex representation)
-        *  +1 (space in between hex and name)
-        *  +1 (newline at the end of the line)
-        */
-       if (line->len <= 42)
-               return NULL;
-
-       if (get_sha1_hex(line->buf, sha1) < 0)
-               return NULL;
-       if (!isspace(line->buf[40]))
-               return NULL;
-
-       ref = line->buf + 41;
-       if (isspace(*ref))
-               return NULL;
-
-       if (line->buf[line->len - 1] != '\n')
-               return NULL;
-       line->buf[--line->len] = 0;
-
-       return ref;
-}
-
-/*
- * Read f, which is a packed-refs file, into dir.
- *
- * A comment line of the form "# pack-refs with: " may contain zero or
- * more traits. We interpret the traits as follows:
- *
- *   No traits:
- *
- *      Probably no references are peeled. But if the file contains a
- *      peeled value for a reference, we will use it.
- *
- *   peeled:
- *
- *      References under "refs/tags/", if they *can* be peeled, *are*
- *      peeled in this file. References outside of "refs/tags/" are
- *      probably not peeled even if they could have been, but if we find
- *      a peeled value for such a reference we will use it.
- *
- *   fully-peeled:
- *
- *      All references in the file that can be peeled are peeled.
- *      Inversely (and this is more important), any references in the
- *      file for which no peeled value is recorded is not peelable. This
- *      trait should typically be written alongside "peeled" for
- *      compatibility with older clients, but we do not require it
- *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
- */
-static void read_packed_refs(FILE *f, struct ref_dir *dir)
-{
-       struct ref_entry *last = NULL;
-       struct strbuf line = STRBUF_INIT;
-       enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
-
-       while (strbuf_getwholeline(&line, f, '\n') != EOF) {
-               unsigned char sha1[20];
-               const char *refname;
-               const char *traits;
-
-               if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
-                       if (strstr(traits, " fully-peeled "))
-                               peeled = PEELED_FULLY;
-                       else if (strstr(traits, " peeled "))
-                               peeled = PEELED_TAGS;
-                       /* perhaps other traits later as well */
-                       continue;
-               }
-
-               refname = parse_ref_line(&line, sha1);
-               if (refname) {
-                       int flag = REF_ISPACKED;
-
-                       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-                               if (!refname_is_safe(refname))
-                                       die("packed refname is dangerous: %s", refname);
-                               hashclr(sha1);
-                               flag |= REF_BAD_NAME | REF_ISBROKEN;
-                       }
-                       last = create_ref_entry(refname, sha1, flag, 0);
-                       if (peeled == PEELED_FULLY ||
-                           (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
-                               last->flag |= REF_KNOWS_PEELED;
-                       add_ref(dir, last);
-                       continue;
-               }
-               if (last &&
-                   line.buf[0] == '^' &&
-                   line.len == PEELED_LINE_LENGTH &&
-                   line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
-                   !get_sha1_hex(line.buf + 1, sha1)) {
-                       hashcpy(last->u.value.peeled.hash, sha1);
-                       /*
-                        * Regardless of what the file header said,
-                        * we definitely know the value of *this*
-                        * reference:
-                        */
-                       last->flag |= REF_KNOWS_PEELED;
-               }
-       }
-
-       strbuf_release(&line);
-}
-
-/*
- * Get the packed_ref_cache for the specified ref_cache, creating it
- * if necessary.
- */
-static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
-{
-       char *packed_refs_file;
-
-       if (*refs->name)
-               packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
-       else
-               packed_refs_file = git_pathdup("packed-refs");
-
-       if (refs->packed &&
-           !stat_validity_check(&refs->packed->validity, packed_refs_file))
-               clear_packed_ref_cache(refs);
-
-       if (!refs->packed) {
-               FILE *f;
-
-               refs->packed = xcalloc(1, sizeof(*refs->packed));
-               acquire_packed_ref_cache(refs->packed);
-               refs->packed->root = create_dir_entry(refs, "", 0, 0);
-               f = fopen(packed_refs_file, "r");
-               if (f) {
-                       stat_validity_update(&refs->packed->validity, fileno(f));
-                       read_packed_refs(f, get_ref_dir(refs->packed->root));
-                       fclose(f);
-               }
-       }
-       free(packed_refs_file);
-       return refs->packed;
-}
-
-static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
-{
-       return get_ref_dir(packed_ref_cache->root);
-}
-
-static struct ref_dir *get_packed_refs(struct ref_cache *refs)
-{
-       return get_packed_ref_dir(get_packed_ref_cache(refs));
-}
-
-/*
- * Add a reference to the in-memory packed reference cache.  This may
- * only be called while the packed-refs file is locked (see
- * lock_packed_refs()).  To actually write the packed-refs file, call
- * commit_packed_refs().
- */
-static void add_packed_ref(const char *refname, const unsigned char *sha1)
-{
-       struct packed_ref_cache *packed_ref_cache =
-               get_packed_ref_cache(&ref_cache);
-
-       if (!packed_ref_cache->lock)
-               die("internal error: packed refs not locked");
-       add_ref(get_packed_ref_dir(packed_ref_cache),
-               create_ref_entry(refname, sha1, REF_ISPACKED, 1));
-}
-
-/*
- * Read the loose references from the namespace dirname into dir
- * (without recursing).  dirname must end with '/'.  dir must be the
- * directory entry corresponding to dirname.
- */
-static void read_loose_refs(const char *dirname, struct ref_dir *dir)
-{
-       struct ref_cache *refs = dir->ref_cache;
-       DIR *d;
-       struct dirent *de;
-       int dirnamelen = strlen(dirname);
-       struct strbuf refname;
-       struct strbuf path = STRBUF_INIT;
-       size_t path_baselen;
-
-       if (*refs->name)
-               strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
-       else
-               strbuf_git_path(&path, "%s", dirname);
-       path_baselen = path.len;
-
-       d = opendir(path.buf);
-       if (!d) {
-               strbuf_release(&path);
-               return;
-       }
-
-       strbuf_init(&refname, dirnamelen + 257);
-       strbuf_add(&refname, dirname, dirnamelen);
-
-       while ((de = readdir(d)) != NULL) {
-               unsigned char sha1[20];
-               struct stat st;
-               int flag;
-
-               if (de->d_name[0] == '.')
-                       continue;
-               if (ends_with(de->d_name, ".lock"))
-                       continue;
-               strbuf_addstr(&refname, de->d_name);
-               strbuf_addstr(&path, de->d_name);
-               if (stat(path.buf, &st) < 0) {
-                       ; /* silently ignore */
-               } else if (S_ISDIR(st.st_mode)) {
-                       strbuf_addch(&refname, '/');
-                       add_entry_to_dir(dir,
-                                        create_dir_entry(refs, refname.buf,
-                                                         refname.len, 1));
-               } else {
-                       int read_ok;
-
-                       if (*refs->name) {
-                               hashclr(sha1);
-                               flag = 0;
-                               read_ok = !resolve_gitlink_ref(refs->name,
-                                                              refname.buf, sha1);
-                       } else {
-                               read_ok = !read_ref_full(refname.buf,
-                                                        RESOLVE_REF_READING,
-                                                        sha1, &flag);
-                       }
-
-                       if (!read_ok) {
-                               hashclr(sha1);
-                               flag |= REF_ISBROKEN;
-                       } else if (is_null_sha1(sha1)) {
-                               /*
-                                * It is so astronomically unlikely
-                                * that NULL_SHA1 is the SHA-1 of an
-                                * actual object that we consider its
-                                * appearance in a loose reference
-                                * file to be repo corruption
-                                * (probably due to a software bug).
-                                */
-                               flag |= REF_ISBROKEN;
-                       }
-
-                       if (check_refname_format(refname.buf,
-                                                REFNAME_ALLOW_ONELEVEL)) {
-                               if (!refname_is_safe(refname.buf))
-                                       die("loose refname is dangerous: %s", refname.buf);
-                               hashclr(sha1);
-                               flag |= REF_BAD_NAME | REF_ISBROKEN;
-                       }
-                       add_entry_to_dir(dir,
-                                        create_ref_entry(refname.buf, sha1, flag, 0));
-               }
-               strbuf_setlen(&refname, dirnamelen);
-               strbuf_setlen(&path, path_baselen);
-       }
-       strbuf_release(&refname);
-       strbuf_release(&path);
-       closedir(d);
-}
-
-static struct ref_dir *get_loose_refs(struct ref_cache *refs)
-{
-       if (!refs->loose) {
-               /*
-                * Mark the top-level directory complete because we
-                * are about to read the only subdirectory that can
-                * hold references:
-                */
-               refs->loose = create_dir_entry(refs, "", 0, 0);
-               /*
-                * Create an incomplete entry for "refs/":
-                */
-               add_entry_to_dir(get_ref_dir(refs->loose),
-                                create_dir_entry(refs, "refs/", 5, 1));
-       }
-       return get_ref_dir(refs->loose);
-}
-
-/* We allow "recursive" symbolic refs. Only within reason, though */
-#define MAXDEPTH 5
-#define MAXREFLEN (1024)
-
-/*
- * Called by resolve_gitlink_ref_recursive() after it failed to read
- * from the loose refs in ref_cache refs. Find <refname> in the
- * packed-refs file for the submodule.
- */
-static int resolve_gitlink_packed_ref(struct ref_cache *refs,
-                                     const char *refname, unsigned char *sha1)
-{
-       struct ref_entry *ref;
-       struct ref_dir *dir = get_packed_refs(refs);
-
-       ref = find_ref(dir, refname);
-       if (ref == NULL)
-               return -1;
-
-       hashcpy(sha1, ref->u.value.oid.hash);
-       return 0;
-}
-
-static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
-                                        const char *refname, unsigned char *sha1,
-                                        int recursion)
-{
-       int fd, len;
-       char buffer[128], *p;
-       char *path;
-
-       if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
-               return -1;
-       path = *refs->name
-               ? git_pathdup_submodule(refs->name, "%s", refname)
-               : git_pathdup("%s", refname);
-       fd = open(path, O_RDONLY);
-       free(path);
-       if (fd < 0)
-               return resolve_gitlink_packed_ref(refs, refname, sha1);
-
-       len = read(fd, buffer, sizeof(buffer)-1);
-       close(fd);
-       if (len < 0)
-               return -1;
-       while (len && isspace(buffer[len-1]))
-               len--;
-       buffer[len] = 0;
-
-       /* Was it a detached head or an old-fashioned symlink? */
-       if (!get_sha1_hex(buffer, sha1))
-               return 0;
-
-       /* Symref? */
-       if (strncmp(buffer, "ref:", 4))
-               return -1;
-       p = buffer + 4;
-       while (isspace(*p))
-               p++;
-
-       return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
-}
-
-int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
-{
-       int len = strlen(path), retval;
-       char *submodule;
-       struct ref_cache *refs;
-
-       while (len && path[len-1] == '/')
-               len--;
-       if (!len)
-               return -1;
-       submodule = xstrndup(path, len);
-       refs = get_ref_cache(submodule);
-       free(submodule);
-
-       retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
-       return retval;
-}
-
-/*
- * Return the ref_entry for the given refname from the packed
- * references.  If it does not exist, return NULL.
- */
-static struct ref_entry *get_packed_ref(const char *refname)
-{
-       return find_ref(get_packed_refs(&ref_cache), refname);
-}
-
-/*
- * A loose ref file doesn't exist; check for a packed ref.  The
- * options are forwarded from resolve_safe_unsafe().
- */
-static int resolve_missing_loose_ref(const char *refname,
-                                    int resolve_flags,
-                                    unsigned char *sha1,
-                                    int *flags)
-{
-       struct ref_entry *entry;
-
-       /*
-        * The loose reference file does not exist; check for a packed
-        * reference.
-        */
-       entry = get_packed_ref(refname);
-       if (entry) {
-               hashcpy(sha1, entry->u.value.oid.hash);
-               if (flags)
-                       *flags |= REF_ISPACKED;
-               return 0;
-       }
-       /* The reference is not a packed reference, either. */
-       if (resolve_flags & RESOLVE_REF_READING) {
-               errno = ENOENT;
-               return -1;
-       } else {
-               hashclr(sha1);
-               return 0;
-       }
-}
-
-/* This function needs to return a meaningful errno on failure */
-static const char *resolve_ref_1(const char *refname,
-                                int resolve_flags,
-                                unsigned char *sha1,
-                                int *flags,
-                                struct strbuf *sb_refname,
-                                struct strbuf *sb_path,
-                                struct strbuf *sb_contents)
-{
-       int depth = MAXDEPTH;
-       int bad_name = 0;
-
-       if (flags)
-               *flags = 0;
-
-       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-               if (flags)
-                       *flags |= REF_BAD_NAME;
-
-               if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
-                   !refname_is_safe(refname)) {
-                       errno = EINVAL;
-                       return NULL;
-               }
-               /*
-                * dwim_ref() uses REF_ISBROKEN to distinguish between
-                * missing refs and refs that were present but invalid,
-                * to complain about the latter to stderr.
-                *
-                * We don't know whether the ref exists, so don't set
-                * REF_ISBROKEN yet.
-                */
-               bad_name = 1;
-       }
-       for (;;) {
-               const char *path;
-               struct stat st;
-               char *buf;
+       if (old_sha1 && !is_null_sha1(old_sha1)) {
                int fd;
+               unsigned char actual_old_sha1[20];
 
-               if (--depth < 0) {
-                       errno = ELOOP;
-                       return NULL;
-               }
-
-               strbuf_reset(sb_path);
-               strbuf_git_path(sb_path, "%s", refname);
-               path = sb_path->buf;
-
-               /*
-                * We might have to loop back here to avoid a race
-                * condition: first we lstat() the file, then we try
-                * to read it as a link or as a file.  But if somebody
-                * changes the type of the file (file <-> directory
-                * <-> symlink) between the lstat() and reading, then
-                * we don't want to report that as an error but rather
-                * try again starting with the lstat().
-                */
-       stat_ref:
-               if (lstat(path, &st) < 0) {
-                       if (errno != ENOENT)
-                               return NULL;
-                       if (resolve_missing_loose_ref(refname, resolve_flags,
-                                                     sha1, flags))
-                               return NULL;
-                       if (bad_name) {
-                               hashclr(sha1);
-                               if (flags)
-                                       *flags |= REF_ISBROKEN;
-                       }
-                       return refname;
-               }
-
-               /* Follow "normalized" - ie "refs/.." symlinks by hand */
-               if (S_ISLNK(st.st_mode)) {
-                       strbuf_reset(sb_contents);
-                       if (strbuf_readlink(sb_contents, path, 0) < 0) {
-                               if (errno == ENOENT || errno == EINVAL)
-                                       /* inconsistent with lstat; retry */
-                                       goto stat_ref;
-                               else
-                                       return NULL;
-                       }
-                       if (starts_with(sb_contents->buf, "refs/") &&
-                           !check_refname_format(sb_contents->buf, 0)) {
-                               strbuf_swap(sb_refname, sb_contents);
-                               refname = sb_refname->buf;
-                               if (flags)
-                                       *flags |= REF_ISSYMREF;
-                               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
-                                       hashclr(sha1);
-                                       return refname;
-                               }
-                               continue;
-                       }
-               }
-
-               /* Is it a directory? */
-               if (S_ISDIR(st.st_mode)) {
-                       errno = EISDIR;
-                       return NULL;
-               }
-
-               /*
-                * Anything else, just open it and try to use it as
-                * a ref
-                */
-               fd = open(path, O_RDONLY);
-               if (fd < 0) {
-                       if (errno == ENOENT)
-                               /* inconsistent with lstat; retry */
-                               goto stat_ref;
-                       else
-                               return NULL;
-               }
-               strbuf_reset(sb_contents);
-               if (strbuf_read(sb_contents, fd, 256) < 0) {
-                       int save_errno = errno;
-                       close(fd);
-                       errno = save_errno;
-                       return NULL;
-               }
-               close(fd);
-               strbuf_rtrim(sb_contents);
-
-               /*
-                * Is it a symbolic ref?
-                */
-               if (!starts_with(sb_contents->buf, "ref:")) {
-                       /*
-                        * Please note that FETCH_HEAD has a second
-                        * line containing other data.
-                        */
-                       if (get_sha1_hex(sb_contents->buf, sha1) ||
-                           (sb_contents->buf[40] != '\0' && !isspace(sb_contents->buf[40]))) {
-                               if (flags)
-                                       *flags |= REF_ISBROKEN;
-                               errno = EINVAL;
-                               return NULL;
-                       }
-                       if (bad_name) {
-                               hashclr(sha1);
-                               if (flags)
-                                       *flags |= REF_ISBROKEN;
-                       }
-                       return refname;
-               }
-               if (flags)
-                       *flags |= REF_ISSYMREF;
-               buf = sb_contents->buf + 4;
-               while (isspace(*buf))
-                       buf++;
-               strbuf_reset(sb_refname);
-               strbuf_addstr(sb_refname, buf);
-               refname = sb_refname->buf;
-               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
-                       hashclr(sha1);
-                       return refname;
-               }
-               if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
-                       if (flags)
-                               *flags |= REF_ISBROKEN;
-
-                       if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
-                           !refname_is_safe(buf)) {
-                               errno = EINVAL;
-                               return NULL;
-                       }
-                       bad_name = 1;
-               }
-       }
-}
-
-const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
-                              unsigned char *sha1, int *flags)
-{
-       static struct strbuf sb_refname = STRBUF_INIT;
-       struct strbuf sb_contents = STRBUF_INIT;
-       struct strbuf sb_path = STRBUF_INIT;
-       const char *ret;
-
-       ret = resolve_ref_1(refname, resolve_flags, sha1, flags,
-                           &sb_refname, &sb_path, &sb_contents);
-       strbuf_release(&sb_path);
-       strbuf_release(&sb_contents);
-       return ret;
-}
-
-char *resolve_refdup(const char *refname, int resolve_flags,
-                    unsigned char *sha1, int *flags)
-{
-       return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
-                                                 sha1, flags));
-}
-
-/* The argument to filter_refs */
-struct ref_filter {
-       const char *pattern;
-       each_ref_fn *fn;
-       void *cb_data;
-};
-
-int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
-{
-       if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
-               return 0;
-       return -1;
-}
-
-int read_ref(const char *refname, unsigned char *sha1)
-{
-       return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
-}
-
-int ref_exists(const char *refname)
-{
-       unsigned char sha1[20];
-       return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
-}
-
-static int filter_refs(const char *refname, const struct object_id *oid,
-                          int flags, void *data)
-{
-       struct ref_filter *filter = (struct ref_filter *)data;
-
-       if (wildmatch(filter->pattern, refname, 0, NULL))
-               return 0;
-       return filter->fn(refname, oid, flags, filter->cb_data);
-}
-
-enum peel_status {
-       /* object was peeled successfully: */
-       PEEL_PEELED = 0,
-
-       /*
-        * object cannot be peeled because the named object (or an
-        * object referred to by a tag in the peel chain), does not
-        * exist.
-        */
-       PEEL_INVALID = -1,
-
-       /* object cannot be peeled because it is not a tag: */
-       PEEL_NON_TAG = -2,
-
-       /* ref_entry contains no peeled value because it is a symref: */
-       PEEL_IS_SYMREF = -3,
-
-       /*
-        * ref_entry cannot be peeled because it is broken (i.e., the
-        * symbolic reference cannot even be resolved to an object
-        * name):
-        */
-       PEEL_BROKEN = -4
-};
-
-/*
- * Peel the named object; i.e., if the object is a tag, resolve the
- * tag recursively until a non-tag is found.  If successful, store the
- * result to sha1 and return PEEL_PEELED.  If the object is not a tag
- * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
- * and leave sha1 unchanged.
- */
-static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
-{
-       struct object *o = lookup_unknown_object(name);
-
-       if (o->type == OBJ_NONE) {
-               int type = sha1_object_info(name, NULL);
-               if (type < 0 || !object_as_type(o, type, 0))
-                       return PEEL_INVALID;
-       }
-
-       if (o->type != OBJ_TAG)
-               return PEEL_NON_TAG;
-
-       o = deref_tag_noverify(o);
-       if (!o)
-               return PEEL_INVALID;
-
-       hashcpy(sha1, o->sha1);
-       return PEEL_PEELED;
-}
-
-/*
- * Peel the entry (if possible) and return its new peel_status.  If
- * repeel is true, re-peel the entry even if there is an old peeled
- * value that is already stored in it.
- *
- * It is OK to call this function with a packed reference entry that
- * might be stale and might even refer to an object that has since
- * been garbage-collected.  In such a case, if the entry has
- * REF_KNOWS_PEELED then leave the status unchanged and return
- * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
- */
-static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
-{
-       enum peel_status status;
-
-       if (entry->flag & REF_KNOWS_PEELED) {
-               if (repeel) {
-                       entry->flag &= ~REF_KNOWS_PEELED;
-                       oidclr(&entry->u.value.peeled);
-               } else {
-                       return is_null_oid(&entry->u.value.peeled) ?
-                               PEEL_NON_TAG : PEEL_PEELED;
-               }
-       }
-       if (entry->flag & REF_ISBROKEN)
-               return PEEL_BROKEN;
-       if (entry->flag & REF_ISSYMREF)
-               return PEEL_IS_SYMREF;
-
-       status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
-       if (status == PEEL_PEELED || status == PEEL_NON_TAG)
-               entry->flag |= REF_KNOWS_PEELED;
-       return status;
-}
-
-int peel_ref(const char *refname, unsigned char *sha1)
-{
-       int flag;
-       unsigned char base[20];
-
-       if (current_ref && (current_ref->name == refname
-                           || !strcmp(current_ref->name, refname))) {
-               if (peel_entry(current_ref, 0))
-                       return -1;
-               hashcpy(sha1, current_ref->u.value.peeled.hash);
-               return 0;
-       }
-
-       if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
-               return -1;
-
-       /*
-        * If the reference is packed, read its ref_entry from the
-        * cache in the hope that we already know its peeled value.
-        * We only try this optimization on packed references because
-        * (a) forcing the filling of the loose reference cache could
-        * be expensive and (b) loose references anyway usually do not
-        * have REF_KNOWS_PEELED.
-        */
-       if (flag & REF_ISPACKED) {
-               struct ref_entry *r = get_packed_ref(refname);
-               if (r) {
-                       if (peel_entry(r, 0))
-                               return -1;
-                       hashcpy(sha1, r->u.value.peeled.hash);
-                       return 0;
-               }
-       }
-
-       return peel_object(base, sha1);
-}
-
-struct warn_if_dangling_data {
-       FILE *fp;
-       const char *refname;
-       const struct string_list *refnames;
-       const char *msg_fmt;
-};
-
-static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
-                                  int flags, void *cb_data)
-{
-       struct warn_if_dangling_data *d = cb_data;
-       const char *resolves_to;
-       struct object_id junk;
-
-       if (!(flags & REF_ISSYMREF))
-               return 0;
-
-       resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
-       if (!resolves_to
-           || (d->refname
-               ? strcmp(resolves_to, d->refname)
-               : !string_list_has_string(d->refnames, resolves_to))) {
-               return 0;
-       }
-
-       fprintf(d->fp, d->msg_fmt, refname);
-       fputc('\n', d->fp);
-       return 0;
-}
-
-void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
-{
-       struct warn_if_dangling_data data;
-
-       data.fp = fp;
-       data.refname = refname;
-       data.refnames = NULL;
-       data.msg_fmt = msg_fmt;
-       for_each_rawref(warn_if_dangling_symref, &data);
-}
-
-void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
-{
-       struct warn_if_dangling_data data;
-
-       data.fp = fp;
-       data.refname = NULL;
-       data.refnames = refnames;
-       data.msg_fmt = msg_fmt;
-       for_each_rawref(warn_if_dangling_symref, &data);
-}
-
-/*
- * Call fn for each reference in the specified ref_cache, omitting
- * references not in the containing_dir of base.  fn is called for all
- * references, including broken ones.  If fn ever returns a non-zero
- * value, stop the iteration and return that value; otherwise, return
- * 0.
- */
-static int do_for_each_entry(struct ref_cache *refs, const char *base,
-                            each_ref_entry_fn fn, void *cb_data)
-{
-       struct packed_ref_cache *packed_ref_cache;
-       struct ref_dir *loose_dir;
-       struct ref_dir *packed_dir;
-       int retval = 0;
-
-       /*
-        * We must make sure that all loose refs are read before accessing the
-        * packed-refs file; this avoids a race condition in which loose refs
-        * are migrated to the packed-refs file by a simultaneous process, but
-        * our in-memory view is from before the migration. get_packed_ref_cache()
-        * takes care of making sure our view is up to date with what is on
-        * disk.
-        */
-       loose_dir = get_loose_refs(refs);
-       if (base && *base) {
-               loose_dir = find_containing_dir(loose_dir, base, 0);
-       }
-       if (loose_dir)
-               prime_ref_dir(loose_dir);
-
-       packed_ref_cache = get_packed_ref_cache(refs);
-       acquire_packed_ref_cache(packed_ref_cache);
-       packed_dir = get_packed_ref_dir(packed_ref_cache);
-       if (base && *base) {
-               packed_dir = find_containing_dir(packed_dir, base, 0);
-       }
-
-       if (packed_dir && loose_dir) {
-               sort_ref_dir(packed_dir);
-               sort_ref_dir(loose_dir);
-               retval = do_for_each_entry_in_dirs(
-                               packed_dir, loose_dir, fn, cb_data);
-       } else if (packed_dir) {
-               sort_ref_dir(packed_dir);
-               retval = do_for_each_entry_in_dir(
-                               packed_dir, 0, fn, cb_data);
-       } else if (loose_dir) {
-               sort_ref_dir(loose_dir);
-               retval = do_for_each_entry_in_dir(
-                               loose_dir, 0, fn, cb_data);
-       }
-
-       release_packed_ref_cache(packed_ref_cache);
-       return retval;
-}
-
-/*
- * Call fn for each reference in the specified ref_cache for which the
- * refname begins with base.  If trim is non-zero, then trim that many
- * characters off the beginning of each refname before passing the
- * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
- * broken references in the iteration.  If fn ever returns a non-zero
- * value, stop the iteration and return that value; otherwise, return
- * 0.
- */
-static int do_for_each_ref(struct ref_cache *refs, const char *base,
-                          each_ref_fn fn, int trim, int flags, void *cb_data)
-{
-       struct ref_entry_cb data;
-       data.base = base;
-       data.trim = trim;
-       data.flags = flags;
-       data.fn = fn;
-       data.cb_data = cb_data;
-
-       if (ref_paranoia < 0)
-               ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
-       if (ref_paranoia)
-               data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
-
-       return do_for_each_entry(refs, base, do_one_ref, &data);
-}
-
-static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       struct object_id oid;
-       int flag;
-
-       if (submodule) {
-               if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
-                       return fn("HEAD", &oid, 0, cb_data);
-
-               return 0;
-       }
-
-       if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
-               return fn("HEAD", &oid, flag, cb_data);
-
-       return 0;
-}
-
-int head_ref(each_ref_fn fn, void *cb_data)
-{
-       return do_head_ref(NULL, fn, cb_data);
-}
-
-int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       return do_head_ref(submodule, fn, cb_data);
-}
-
-int for_each_ref(each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
-}
-
-int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
-}
-
-int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
-}
-
-int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
-{
-       unsigned int flag = 0;
-
-       if (broken)
-               flag = DO_FOR_EACH_INCLUDE_BROKEN;
-       return do_for_each_ref(&ref_cache, prefix, fn, 0, flag, cb_data);
-}
-
-int for_each_ref_in_submodule(const char *submodule, const char *prefix,
-               each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
-}
-
-int for_each_tag_ref(each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in("refs/tags/", fn, cb_data);
-}
-
-int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
-}
-
-int for_each_branch_ref(each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in("refs/heads/", fn, cb_data);
-}
-
-int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
-}
-
-int for_each_remote_ref(each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in("refs/remotes/", fn, cb_data);
-}
-
-int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-       return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
-}
-
-int for_each_replace_ref(each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(&ref_cache, git_replace_ref_base, fn,
-                              strlen(git_replace_ref_base), 0, cb_data);
-}
-
-int head_ref_namespaced(each_ref_fn fn, void *cb_data)
-{
-       struct strbuf buf = STRBUF_INIT;
-       int ret = 0;
-       struct object_id oid;
-       int flag;
-
-       strbuf_addf(&buf, "%sHEAD", get_git_namespace());
-       if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
-               ret = fn(buf.buf, &oid, flag, cb_data);
-       strbuf_release(&buf);
-
-       return ret;
-}
-
-int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
-{
-       struct strbuf buf = STRBUF_INIT;
-       int ret;
-       strbuf_addf(&buf, "%srefs/", get_git_namespace());
-       ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
-       strbuf_release(&buf);
-       return ret;
-}
-
-int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
-       const char *prefix, void *cb_data)
-{
-       struct strbuf real_pattern = STRBUF_INIT;
-       struct ref_filter filter;
-       int ret;
-
-       if (!prefix && !starts_with(pattern, "refs/"))
-               strbuf_addstr(&real_pattern, "refs/");
-       else if (prefix)
-               strbuf_addstr(&real_pattern, prefix);
-       strbuf_addstr(&real_pattern, pattern);
-
-       if (!has_glob_specials(pattern)) {
-               /* Append implied '/' '*' if not present. */
-               strbuf_complete(&real_pattern, '/');
-               /* No need to check for '*', there is none. */
-               strbuf_addch(&real_pattern, '*');
-       }
-
-       filter.pattern = real_pattern.buf;
-       filter.fn = fn;
-       filter.cb_data = cb_data;
-       ret = for_each_ref(filter_refs, &filter);
-
-       strbuf_release(&real_pattern);
-       return ret;
-}
-
-int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
-{
-       return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
-}
-
-int for_each_rawref(each_ref_fn fn, void *cb_data)
-{
-       return do_for_each_ref(&ref_cache, "", fn, 0,
-                              DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
-}
-
-const char *prettify_refname(const char *name)
-{
-       return name + (
-               starts_with(name, "refs/heads/") ? 11 :
-               starts_with(name, "refs/tags/") ? 10 :
-               starts_with(name, "refs/remotes/") ? 13 :
-               0);
-}
-
-static const char *ref_rev_parse_rules[] = {
-       "%.*s",
-       "refs/%.*s",
-       "refs/tags/%.*s",
-       "refs/heads/%.*s",
-       "refs/remotes/%.*s",
-       "refs/remotes/%.*s/HEAD",
-       NULL
-};
-
-int refname_match(const char *abbrev_name, const char *full_name)
-{
-       const char **p;
-       const int abbrev_name_len = strlen(abbrev_name);
-
-       for (p = ref_rev_parse_rules; *p; p++) {
-               if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
-                       return 1;
-               }
-       }
-
-       return 0;
-}
-
-static void unlock_ref(struct ref_lock *lock)
-{
-       /* Do not free lock->lk -- atexit() still looks at them */
-       if (lock->lk)
-               rollback_lock_file(lock->lk);
-       free(lock->ref_name);
-       free(lock->orig_ref_name);
-       free(lock);
-}
-
-/*
- * Verify that the reference locked by lock has the value old_sha1.
- * Fail if the reference doesn't exist and mustexist is set. Return 0
- * on success. On error, write an error message to err, set errno, and
- * return a negative value.
- */
-static int verify_lock(struct ref_lock *lock,
-                      const unsigned char *old_sha1, int mustexist,
-                      struct strbuf *err)
-{
-       assert(err);
-
-       if (read_ref_full(lock->ref_name,
-                         mustexist ? RESOLVE_REF_READING : 0,
-                         lock->old_oid.hash, NULL)) {
-               int save_errno = errno;
-               strbuf_addf(err, "can't verify ref %s", lock->ref_name);
-               errno = save_errno;
-               return -1;
-       }
-       if (hashcmp(lock->old_oid.hash, old_sha1)) {
-               strbuf_addf(err, "ref %s is at %s but expected %s",
-                           lock->ref_name,
-                           sha1_to_hex(lock->old_oid.hash),
-                           sha1_to_hex(old_sha1));
-               errno = EBUSY;
-               return -1;
-       }
-       return 0;
-}
-
-static int remove_empty_directories(struct strbuf *path)
-{
-       /*
-        * we want to create a file but there is a directory there;
-        * if that is an empty directory (or a directory that contains
-        * only empty directories), remove them.
-        */
-       return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
-}
-
-/*
- * *string and *len will only be substituted, and *string returned (for
- * later free()ing) if the string passed in is a magic short-hand form
- * to name a branch.
- */
-static char *substitute_branch_name(const char **string, int *len)
-{
-       struct strbuf buf = STRBUF_INIT;
-       int ret = interpret_branch_name(*string, *len, &buf);
-
-       if (ret == *len) {
-               size_t size;
-               *string = strbuf_detach(&buf, &size);
-               *len = size;
-               return (char *)*string;
-       }
-
-       return NULL;
-}
-
-int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
-{
-       char *last_branch = substitute_branch_name(&str, &len);
-       const char **p, *r;
-       int refs_found = 0;
-
-       *ref = NULL;
-       for (p = ref_rev_parse_rules; *p; p++) {
-               char fullref[PATH_MAX];
-               unsigned char sha1_from_ref[20];
-               unsigned char *this_result;
-               int flag;
-
-               this_result = refs_found ? sha1_from_ref : sha1;
-               mksnpath(fullref, sizeof(fullref), *p, len, str);
-               r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
-                                      this_result, &flag);
-               if (r) {
-                       if (!refs_found++)
-                               *ref = xstrdup(r);
-                       if (!warn_ambiguous_refs)
-                               break;
-               } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
-                       warning("ignoring dangling symref %s.", fullref);
-               } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
-                       warning("ignoring broken ref %s.", fullref);
-               }
-       }
-       free(last_branch);
-       return refs_found;
-}
-
-int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
-{
-       char *last_branch = substitute_branch_name(&str, &len);
-       const char **p;
-       int logs_found = 0;
-
-       *log = NULL;
-       for (p = ref_rev_parse_rules; *p; p++) {
-               unsigned char hash[20];
-               char path[PATH_MAX];
-               const char *ref, *it;
-
-               mksnpath(path, sizeof(path), *p, len, str);
-               ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
-                                        hash, NULL);
-               if (!ref)
-                       continue;
-               if (reflog_exists(path))
-                       it = path;
-               else if (strcmp(ref, path) && reflog_exists(ref))
-                       it = ref;
-               else
-                       continue;
-               if (!logs_found++) {
-                       *log = xstrdup(it);
-                       hashcpy(sha1, hash);
-               }
-               if (!warn_ambiguous_refs)
-                       break;
-       }
-       free(last_branch);
-       return logs_found;
-}
-
-/*
- * Locks a ref returning the lock on success and NULL on failure.
- * On failure errno is set to something meaningful.
- */
-static struct ref_lock *lock_ref_sha1_basic(const char *refname,
-                                           const unsigned char *old_sha1,
-                                           const struct string_list *extras,
-                                           const struct string_list *skip,
-                                           unsigned int flags, int *type_p,
-                                           struct strbuf *err)
-{
-       struct strbuf ref_file = STRBUF_INIT;
-       struct strbuf orig_ref_file = STRBUF_INIT;
-       const char *orig_refname = refname;
-       struct ref_lock *lock;
-       int last_errno = 0;
-       int type, lflags;
-       int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
-       int resolve_flags = 0;
-       int attempts_remaining = 3;
-
-       assert(err);
-
-       lock = xcalloc(1, sizeof(struct ref_lock));
-
-       if (mustexist)
-               resolve_flags |= RESOLVE_REF_READING;
-       if (flags & REF_DELETING) {
-               resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
-               if (flags & REF_NODEREF)
-                       resolve_flags |= RESOLVE_REF_NO_RECURSE;
-       }
-
-       refname = resolve_ref_unsafe(refname, resolve_flags,
-                                    lock->old_oid.hash, &type);
-       if (!refname && errno == EISDIR) {
-               /*
-                * we are trying to lock foo but we used to
-                * have foo/bar which now does not exist;
-                * it is normal for the empty directory 'foo'
-                * to remain.
-                */
-               strbuf_git_path(&orig_ref_file, "%s", orig_refname);
-               if (remove_empty_directories(&orig_ref_file)) {
-                       last_errno = errno;
-                       if (!verify_refname_available_dir(orig_refname, extras, skip,
-                                                         get_loose_refs(&ref_cache), err))
-                               strbuf_addf(err, "there are still refs under '%s'",
-                                           orig_refname);
-                       goto error_return;
-               }
-               refname = resolve_ref_unsafe(orig_refname, resolve_flags,
-                                            lock->old_oid.hash, &type);
-       }
-       if (type_p)
-           *type_p = type;
-       if (!refname) {
-               last_errno = errno;
-               if (last_errno != ENOTDIR ||
-                   !verify_refname_available_dir(orig_refname, extras, skip,
-                                                 get_loose_refs(&ref_cache), err))
-                       strbuf_addf(err, "unable to resolve reference %s: %s",
-                                   orig_refname, strerror(last_errno));
-
-               goto error_return;
-       }
-       /*
-        * If the ref did not exist and we are creating it, make sure
-        * there is no existing packed ref whose name begins with our
-        * refname, nor a packed ref whose name is a proper prefix of
-        * our refname.
-        */
-       if (is_null_oid(&lock->old_oid) &&
-           verify_refname_available_dir(refname, extras, skip,
-                                        get_packed_refs(&ref_cache), err)) {
-               last_errno = ENOTDIR;
-               goto error_return;
-       }
-
-       lock->lk = xcalloc(1, sizeof(struct lock_file));
-
-       lflags = 0;
-       if (flags & REF_NODEREF) {
-               refname = orig_refname;
-               lflags |= LOCK_NO_DEREF;
-       }
-       lock->ref_name = xstrdup(refname);
-       lock->orig_ref_name = xstrdup(orig_refname);
-       strbuf_git_path(&ref_file, "%s", refname);
-
- retry:
-       switch (safe_create_leading_directories_const(ref_file.buf)) {
-       case SCLD_OK:
-               break; /* success */
-       case SCLD_VANISHED:
-               if (--attempts_remaining > 0)
-                       goto retry;
-               /* fall through */
-       default:
-               last_errno = errno;
-               strbuf_addf(err, "unable to create directory for %s",
-                           ref_file.buf);
-               goto error_return;
-       }
-
-       if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
-               last_errno = errno;
-               if (errno == ENOENT && --attempts_remaining > 0)
-                       /*
-                        * Maybe somebody just deleted one of the
-                        * directories leading to ref_file.  Try
-                        * again:
-                        */
-                       goto retry;
-               else {
-                       unable_to_lock_message(ref_file.buf, errno, err);
-                       goto error_return;
-               }
-       }
-       if (old_sha1 && verify_lock(lock, old_sha1, mustexist, err)) {
-               last_errno = errno;
-               goto error_return;
-       }
-       goto out;
-
- error_return:
-       unlock_ref(lock);
-       lock = NULL;
-
- out:
-       strbuf_release(&ref_file);
-       strbuf_release(&orig_ref_file);
-       errno = last_errno;
-       return lock;
-}
-
-/*
- * Write an entry to the packed-refs file for the specified refname.
- * If peeled is non-NULL, write it as the entry's peeled value.
- */
-static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
-                              unsigned char *peeled)
-{
-       fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
-       if (peeled)
-               fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
-}
-
-/*
- * An each_ref_entry_fn that writes the entry to a packed-refs file.
- */
-static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
-{
-       enum peel_status peel_status = peel_entry(entry, 0);
-
-       if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
-               error("internal error: %s is not a valid packed reference!",
-                     entry->name);
-       write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
-                          peel_status == PEEL_PEELED ?
-                          entry->u.value.peeled.hash : NULL);
-       return 0;
-}
-
-/*
- * Lock the packed-refs file for writing. Flags is passed to
- * hold_lock_file_for_update(). Return 0 on success. On errors, set
- * errno appropriately and return a nonzero value.
- */
-static int lock_packed_refs(int flags)
-{
-       static int timeout_configured = 0;
-       static int timeout_value = 1000;
-
-       struct packed_ref_cache *packed_ref_cache;
-
-       if (!timeout_configured) {
-               git_config_get_int("core.packedrefstimeout", &timeout_value);
-               timeout_configured = 1;
-       }
-
-       if (hold_lock_file_for_update_timeout(
-                           &packlock, git_path("packed-refs"),
-                           flags, timeout_value) < 0)
-               return -1;
-       /*
-        * Get the current packed-refs while holding the lock.  If the
-        * packed-refs file has been modified since we last read it,
-        * this will automatically invalidate the cache and re-read
-        * the packed-refs file.
-        */
-       packed_ref_cache = get_packed_ref_cache(&ref_cache);
-       packed_ref_cache->lock = &packlock;
-       /* Increment the reference count to prevent it from being freed: */
-       acquire_packed_ref_cache(packed_ref_cache);
-       return 0;
-}
-
-/*
- * Write the current version of the packed refs cache from memory to
- * disk. The packed-refs file must already be locked for writing (see
- * lock_packed_refs()). Return zero on success. On errors, set errno
- * and return a nonzero value
- */
-static int commit_packed_refs(void)
-{
-       struct packed_ref_cache *packed_ref_cache =
-               get_packed_ref_cache(&ref_cache);
-       int error = 0;
-       int save_errno = 0;
-       FILE *out;
-
-       if (!packed_ref_cache->lock)
-               die("internal error: packed-refs not locked");
-
-       out = fdopen_lock_file(packed_ref_cache->lock, "w");
-       if (!out)
-               die_errno("unable to fdopen packed-refs descriptor");
-
-       fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
-       do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
-                                0, write_packed_entry_fn, out);
-
-       if (commit_lock_file(packed_ref_cache->lock)) {
-               save_errno = errno;
-               error = -1;
-       }
-       packed_ref_cache->lock = NULL;
-       release_packed_ref_cache(packed_ref_cache);
-       errno = save_errno;
-       return error;
-}
-
-/*
- * Rollback the lockfile for the packed-refs file, and discard the
- * in-memory packed reference cache.  (The packed-refs file will be
- * read anew if it is needed again after this function is called.)
- */
-static void rollback_packed_refs(void)
-{
-       struct packed_ref_cache *packed_ref_cache =
-               get_packed_ref_cache(&ref_cache);
-
-       if (!packed_ref_cache->lock)
-               die("internal error: packed-refs not locked");
-       rollback_lock_file(packed_ref_cache->lock);
-       packed_ref_cache->lock = NULL;
-       release_packed_ref_cache(packed_ref_cache);
-       clear_packed_ref_cache(&ref_cache);
-}
-
-struct ref_to_prune {
-       struct ref_to_prune *next;
-       unsigned char sha1[20];
-       char name[FLEX_ARRAY];
-};
-
-struct pack_refs_cb_data {
-       unsigned int flags;
-       struct ref_dir *packed_refs;
-       struct ref_to_prune *ref_to_prune;
-};
-
-static int is_per_worktree_ref(const char *refname);
-
-/*
- * An each_ref_entry_fn that is run over loose references only.  If
- * the loose reference can be packed, add an entry in the packed ref
- * cache.  If the reference should be pruned, also add it to
- * ref_to_prune in the pack_refs_cb_data.
- */
-static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
-{
-       struct pack_refs_cb_data *cb = cb_data;
-       enum peel_status peel_status;
-       struct ref_entry *packed_entry;
-       int is_tag_ref = starts_with(entry->name, "refs/tags/");
-
-       /* Do not pack per-worktree refs: */
-       if (is_per_worktree_ref(entry->name))
-               return 0;
-
-       /* ALWAYS pack tags */
-       if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
-               return 0;
-
-       /* Do not pack symbolic or broken refs: */
-       if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
-               return 0;
-
-       /* Add a packed ref cache entry equivalent to the loose entry. */
-       peel_status = peel_entry(entry, 1);
-       if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
-               die("internal error peeling reference %s (%s)",
-                   entry->name, oid_to_hex(&entry->u.value.oid));
-       packed_entry = find_ref(cb->packed_refs, entry->name);
-       if (packed_entry) {
-               /* Overwrite existing packed entry with info from loose entry */
-               packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
-               oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
-       } else {
-               packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
-                                               REF_ISPACKED | REF_KNOWS_PEELED, 0);
-               add_ref(cb->packed_refs, packed_entry);
-       }
-       oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
-
-       /* Schedule the loose reference for pruning if requested. */
-       if ((cb->flags & PACK_REFS_PRUNE)) {
-               int namelen = strlen(entry->name) + 1;
-               struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
-               hashcpy(n->sha1, entry->u.value.oid.hash);
-               memcpy(n->name, entry->name, namelen); /* includes NUL */
-               n->next = cb->ref_to_prune;
-               cb->ref_to_prune = n;
-       }
-       return 0;
-}
-
-/*
- * Remove empty parents, but spare refs/ and immediate subdirs.
- * Note: munges *name.
- */
-static void try_remove_empty_parents(char *name)
-{
-       char *p, *q;
-       int i;
-       p = name;
-       for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
-               while (*p && *p != '/')
-                       p++;
-               /* tolerate duplicate slashes; see check_refname_format() */
-               while (*p == '/')
-                       p++;
-       }
-       for (q = p; *q; q++)
-               ;
-       while (1) {
-               while (q > p && *q != '/')
-                       q--;
-               while (q > p && *(q-1) == '/')
-                       q--;
-               if (q == p)
-                       break;
-               *q = '\0';
-               if (rmdir(git_path("%s", name)))
-                       break;
-       }
-}
-
-/* make sure nobody touched the ref, and unlink */
-static void prune_ref(struct ref_to_prune *r)
-{
-       struct ref_transaction *transaction;
-       struct strbuf err = STRBUF_INIT;
-
-       if (check_refname_format(r->name, 0))
-               return;
-
-       transaction = ref_transaction_begin(&err);
-       if (!transaction ||
-           ref_transaction_delete(transaction, r->name, r->sha1,
-                                  REF_ISPRUNING, NULL, &err) ||
-           ref_transaction_commit(transaction, &err)) {
-               ref_transaction_free(transaction);
-               error("%s", err.buf);
-               strbuf_release(&err);
-               return;
-       }
-       ref_transaction_free(transaction);
-       strbuf_release(&err);
-       try_remove_empty_parents(r->name);
-}
-
-static void prune_refs(struct ref_to_prune *r)
-{
-       while (r) {
-               prune_ref(r);
-               r = r->next;
-       }
-}
-
-int pack_refs(unsigned int flags)
-{
-       struct pack_refs_cb_data cbdata;
-
-       memset(&cbdata, 0, sizeof(cbdata));
-       cbdata.flags = flags;
-
-       lock_packed_refs(LOCK_DIE_ON_ERROR);
-       cbdata.packed_refs = get_packed_refs(&ref_cache);
-
-       do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
-                                pack_if_possible_fn, &cbdata);
-
-       if (commit_packed_refs())
-               die_errno("unable to overwrite old ref-pack file");
-
-       prune_refs(cbdata.ref_to_prune);
-       return 0;
-}
-
-/*
- * Rewrite the packed-refs file, omitting any refs listed in
- * 'refnames'. On error, leave packed-refs unchanged, write an error
- * message to 'err', and return a nonzero value.
- *
- * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
- */
-static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
-{
-       struct ref_dir *packed;
-       struct string_list_item *refname;
-       int ret, needs_repacking = 0, removed = 0;
-
-       assert(err);
-
-       /* Look for a packed ref */
-       for_each_string_list_item(refname, refnames) {
-               if (get_packed_ref(refname->string)) {
-                       needs_repacking = 1;
-                       break;
-               }
-       }
-
-       /* Avoid locking if we have nothing to do */
-       if (!needs_repacking)
-               return 0; /* no refname exists in packed refs */
-
-       if (lock_packed_refs(0)) {
-               unable_to_lock_message(git_path("packed-refs"), errno, err);
-               return -1;
-       }
-       packed = get_packed_refs(&ref_cache);
-
-       /* Remove refnames from the cache */
-       for_each_string_list_item(refname, refnames)
-               if (remove_entry(packed, refname->string) != -1)
-                       removed = 1;
-       if (!removed) {
-               /*
-                * All packed entries disappeared while we were
-                * acquiring the lock.
-                */
-               rollback_packed_refs();
-               return 0;
-       }
-
-       /* Write what remains */
-       ret = commit_packed_refs();
-       if (ret)
-               strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
-                           strerror(errno));
-       return ret;
-}
-
-static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
-{
-       assert(err);
-
-       if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
-               /*
-                * loose.  The loose file name is the same as the
-                * lockfile name, minus ".lock":
-                */
-               char *loose_filename = get_locked_file_path(lock->lk);
-               int res = unlink_or_msg(loose_filename, err);
-               free(loose_filename);
-               if (res)
-                       return 1;
-       }
-       return 0;
-}
-
-static int is_per_worktree_ref(const char *refname)
-{
-       return !strcmp(refname, "HEAD") ||
-               starts_with(refname, "refs/bisect/");
-}
-
-static int is_pseudoref_syntax(const char *refname)
-{
-       const char *c;
-
-       for (c = refname; *c; c++) {
-               if (!isupper(*c) && *c != '-' && *c != '_')
-                       return 0;
-       }
-
-       return 1;
-}
-
-enum ref_type ref_type(const char *refname)
-{
-       if (is_per_worktree_ref(refname))
-               return REF_TYPE_PER_WORKTREE;
-       if (is_pseudoref_syntax(refname))
-               return REF_TYPE_PSEUDOREF;
-       return REF_TYPE_NORMAL;
-}
-
-static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
-                          const unsigned char *old_sha1, struct strbuf *err)
-{
-       const char *filename;
-       int fd;
-       static struct lock_file lock;
-       struct strbuf buf = STRBUF_INIT;
-       int ret = -1;
-
-       strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
-
-       filename = git_path("%s", pseudoref);
-       fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
-       if (fd < 0) {
-               strbuf_addf(err, "Could not open '%s' for writing: %s",
-                           filename, strerror(errno));
-               return -1;
-       }
-
-       if (old_sha1) {
-               unsigned char actual_old_sha1[20];
-
-               if (read_ref(pseudoref, actual_old_sha1))
-                       die("could not read ref '%s'", pseudoref);
-               if (hashcmp(actual_old_sha1, old_sha1)) {
-                       strbuf_addf(err, "Unexpected sha1 when writing %s", pseudoref);
-                       rollback_lock_file(&lock);
-                       goto done;
-               }
-       }
-
-       if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
-               strbuf_addf(err, "Could not write to '%s'", filename);
-               rollback_lock_file(&lock);
-               goto done;
-       }
-
-       commit_lock_file(&lock);
-       ret = 0;
-done:
-       strbuf_release(&buf);
-       return ret;
-}
-
-static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
-{
-       static struct lock_file lock;
-       const char *filename;
-
-       filename = git_path("%s", pseudoref);
-
-       if (old_sha1 && !is_null_sha1(old_sha1)) {
-               int fd;
-               unsigned char actual_old_sha1[20];
-
-               fd = hold_lock_file_for_update(&lock, filename,
-                                              LOCK_DIE_ON_ERROR);
-               if (fd < 0)
-                       die_errno(_("Could not open '%s' for writing"), filename);
-               if (read_ref(pseudoref, actual_old_sha1))
-                       die("could not read ref '%s'", pseudoref);
-               if (hashcmp(actual_old_sha1, old_sha1)) {
-                       warning("Unexpected sha1 when deleting %s", pseudoref);
-                       rollback_lock_file(&lock);
-                       return -1;
-               }
-
-               unlink(filename);
-               rollback_lock_file(&lock);
-       } else {
-               unlink(filename);
-       }
-
-       return 0;
-}
-
-int delete_ref(const char *refname, const unsigned char *old_sha1,
-              unsigned int flags)
-{
-       struct ref_transaction *transaction;
-       struct strbuf err = STRBUF_INIT;
-
-       if (ref_type(refname) == REF_TYPE_PSEUDOREF)
-               return delete_pseudoref(refname, old_sha1);
-
-       transaction = ref_transaction_begin(&err);
-       if (!transaction ||
-           ref_transaction_delete(transaction, refname, old_sha1,
-                                  flags, NULL, &err) ||
-           ref_transaction_commit(transaction, &err)) {
-               error("%s", err.buf);
-               ref_transaction_free(transaction);
-               strbuf_release(&err);
-               return 1;
-       }
-       ref_transaction_free(transaction);
-       strbuf_release(&err);
-       return 0;
-}
-
-int delete_refs(struct string_list *refnames)
-{
-       struct strbuf err = STRBUF_INIT;
-       int i, result = 0;
-
-       if (!refnames->nr)
-               return 0;
-
-       result = repack_without_refs(refnames, &err);
-       if (result) {
-               /*
-                * If we failed to rewrite the packed-refs file, then
-                * it is unsafe to try to remove loose refs, because
-                * doing so might expose an obsolete packed value for
-                * a reference that might even point at an object that
-                * has been garbage collected.
-                */
-               if (refnames->nr == 1)
-                       error(_("could not delete reference %s: %s"),
-                             refnames->items[0].string, err.buf);
-               else
-                       error(_("could not delete references: %s"), err.buf);
-
-               goto out;
-       }
-
-       for (i = 0; i < refnames->nr; i++) {
-               const char *refname = refnames->items[i].string;
-
-               if (delete_ref(refname, NULL, 0))
-                       result |= error(_("could not remove reference %s"), refname);
-       }
-
-out:
-       strbuf_release(&err);
-       return result;
-}
-
-/*
- * People using contrib's git-new-workdir have .git/logs/refs ->
- * /some/other/path/.git/logs/refs, and that may live on another device.
- *
- * IOW, to avoid cross device rename errors, the temporary renamed log must
- * live into logs/refs.
- */
-#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
-
-static int rename_tmp_log(const char *newrefname)
-{
-       int attempts_remaining = 4;
-       struct strbuf path = STRBUF_INIT;
-       int ret = -1;
-
- retry:
-       strbuf_reset(&path);
-       strbuf_git_path(&path, "logs/%s", newrefname);
-       switch (safe_create_leading_directories_const(path.buf)) {
-       case SCLD_OK:
-               break; /* success */
-       case SCLD_VANISHED:
-               if (--attempts_remaining > 0)
-                       goto retry;
-               /* fall through */
-       default:
-               error("unable to create directory for %s", newrefname);
-               goto out;
-       }
-
-       if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
-               if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
-                       /*
-                        * rename(a, b) when b is an existing
-                        * directory ought to result in ISDIR, but
-                        * Solaris 5.8 gives ENOTDIR.  Sheesh.
-                        */
-                       if (remove_empty_directories(&path)) {
-                               error("Directory not empty: logs/%s", newrefname);
-                               goto out;
-                       }
-                       goto retry;
-               } else if (errno == ENOENT && --attempts_remaining > 0) {
-                       /*
-                        * Maybe another process just deleted one of
-                        * the directories in the path to newrefname.
-                        * Try again from the beginning.
-                        */
-                       goto retry;
-               } else {
-                       error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-                               newrefname, strerror(errno));
-                       goto out;
-               }
-       }
-       ret = 0;
-out:
-       strbuf_release(&path);
-       return ret;
-}
-
-/*
- * Return 0 if a reference named refname could be created without
- * conflicting with the name of an existing reference. Otherwise,
- * return a negative value and write an explanation to err. If extras
- * is non-NULL, it is a list of additional refnames with which refname
- * is not allowed to conflict. If skip is non-NULL, ignore potential
- * conflicts with refs in skip (e.g., because they are scheduled for
- * deletion in the same operation). Behavior is undefined if the same
- * name is listed in both extras and skip.
- *
- * Two reference names conflict if one of them exactly matches the
- * leading components of the other; e.g., "foo/bar" conflicts with
- * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
- * "foo/barbados".
- *
- * extras and skip must be sorted.
- */
-static int verify_refname_available(const char *newname,
-                                   struct string_list *extras,
-                                   struct string_list *skip,
-                                   struct strbuf *err)
-{
-       struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
-       struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
-
-       if (verify_refname_available_dir(newname, extras, skip,
-                                        packed_refs, err) ||
-           verify_refname_available_dir(newname, extras, skip,
-                                        loose_refs, err))
-               return -1;
-
-       return 0;
-}
-
-static int rename_ref_available(const char *oldname, const char *newname)
-{
-       struct string_list skip = STRING_LIST_INIT_NODUP;
-       struct strbuf err = STRBUF_INIT;
-       int ret;
-
-       string_list_insert(&skip, oldname);
-       ret = !verify_refname_available(newname, NULL, &skip, &err);
-       if (!ret)
-               error("%s", err.buf);
-
-       string_list_clear(&skip, 0);
-       strbuf_release(&err);
-       return ret;
-}
-
-static int write_ref_to_lockfile(struct ref_lock *lock,
-                                const unsigned char *sha1, struct strbuf *err);
-static int commit_ref_update(struct ref_lock *lock,
-                            const unsigned char *sha1, const char *logmsg,
-                            int flags, struct strbuf *err);
-
-int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
-{
-       unsigned char sha1[20], orig_sha1[20];
-       int flag = 0, logmoved = 0;
-       struct ref_lock *lock;
-       struct stat loginfo;
-       int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
-       const char *symref = NULL;
-       struct strbuf err = STRBUF_INIT;
-
-       if (log && S_ISLNK(loginfo.st_mode))
-               return error("reflog for %s is a symlink", oldrefname);
-
-       symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
-                                   orig_sha1, &flag);
-       if (flag & REF_ISSYMREF)
-               return error("refname %s is a symbolic ref, renaming it is not supported",
-                       oldrefname);
-       if (!symref)
-               return error("refname %s not found", oldrefname);
-
-       if (!rename_ref_available(oldrefname, newrefname))
-               return 1;
-
-       if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
-               return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
-                       oldrefname, strerror(errno));
-
-       if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
-               error("unable to delete old %s", oldrefname);
-               goto rollback;
-       }
-
-       if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
-           delete_ref(newrefname, sha1, REF_NODEREF)) {
-               if (errno==EISDIR) {
-                       struct strbuf path = STRBUF_INIT;
-                       int result;
-
-                       strbuf_git_path(&path, "%s", newrefname);
-                       result = remove_empty_directories(&path);
-                       strbuf_release(&path);
-
-                       if (result) {
-                               error("Directory not empty: %s", newrefname);
-                               goto rollback;
-                       }
-               } else {
-                       error("unable to delete existing %s", newrefname);
-                       goto rollback;
-               }
-       }
-
-       if (log && rename_tmp_log(newrefname))
-               goto rollback;
-
-       logmoved = log;
-
-       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, 0, NULL, &err);
-       if (!lock) {
-               error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
-               strbuf_release(&err);
-               goto rollback;
-       }
-       hashcpy(lock->old_oid.hash, orig_sha1);
-
-       if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-           commit_ref_update(lock, orig_sha1, logmsg, 0, &err)) {
-               error("unable to write current sha1 into %s: %s", newrefname, err.buf);
-               strbuf_release(&err);
-               goto rollback;
-       }
-
-       return 0;
-
- rollback:
-       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, 0, NULL, &err);
-       if (!lock) {
-               error("unable to lock %s for rollback: %s", oldrefname, err.buf);
-               strbuf_release(&err);
-               goto rollbacklog;
-       }
-
-       flag = log_all_ref_updates;
-       log_all_ref_updates = 0;
-       if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-           commit_ref_update(lock, orig_sha1, NULL, 0, &err)) {
-               error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
-               strbuf_release(&err);
-       }
-       log_all_ref_updates = flag;
-
- rollbacklog:
-       if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
-               error("unable to restore logfile %s from %s: %s",
-                       oldrefname, newrefname, strerror(errno));
-       if (!logmoved && log &&
-           rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
-               error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
-                       oldrefname, strerror(errno));
-
-       return 1;
-}
-
-static int close_ref(struct ref_lock *lock)
-{
-       if (close_lock_file(lock->lk))
-               return -1;
-       return 0;
-}
-
-static int commit_ref(struct ref_lock *lock)
-{
-       if (commit_lock_file(lock->lk))
-               return -1;
-       return 0;
-}
-
-/*
- * copy the reflog message msg to buf, which has been allocated sufficiently
- * large, while cleaning up the whitespaces.  Especially, convert LF to space,
- * because reflog file is one line per entry.
- */
-static int copy_reflog_msg(char *buf, const char *msg)
-{
-       char *cp = buf;
-       char c;
-       int wasspace = 1;
-
-       *cp++ = '\t';
-       while ((c = *msg++)) {
-               if (wasspace && isspace(c))
-                       continue;
-               wasspace = isspace(c);
-               if (wasspace)
-                       c = ' ';
-               *cp++ = c;
-       }
-       while (buf < cp && isspace(cp[-1]))
-               cp--;
-       *cp++ = '\n';
-       return cp - buf;
-}
-
-static int should_autocreate_reflog(const char *refname)
-{
-       if (!log_all_ref_updates)
-               return 0;
-       return starts_with(refname, "refs/heads/") ||
-               starts_with(refname, "refs/remotes/") ||
-               starts_with(refname, "refs/notes/") ||
-               !strcmp(refname, "HEAD");
-}
-
-/*
- * Create a reflog for a ref.  If force_create = 0, the reflog will
- * only be created for certain refs (those for which
- * should_autocreate_reflog returns non-zero.  Otherwise, create it
- * regardless of the ref name.  Fill in *err and return -1 on failure.
- */
-static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
-{
-       int logfd, oflags = O_APPEND | O_WRONLY;
-
-       strbuf_git_path(logfile, "logs/%s", refname);
-       if (force_create || should_autocreate_reflog(refname)) {
-               if (safe_create_leading_directories(logfile->buf) < 0) {
-                       strbuf_addf(err, "unable to create directory for %s: "
-                                   "%s", logfile->buf, strerror(errno));
-                       return -1;
-               }
-               oflags |= O_CREAT;
-       }
-
-       logfd = open(logfile->buf, oflags, 0666);
-       if (logfd < 0) {
-               if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
-                       return 0;
-
-               if (errno == EISDIR) {
-                       if (remove_empty_directories(logfile)) {
-                               strbuf_addf(err, "There are still logs under "
-                                           "'%s'", logfile->buf);
-                               return -1;
-                       }
-                       logfd = open(logfile->buf, oflags, 0666);
-               }
-
-               if (logfd < 0) {
-                       strbuf_addf(err, "unable to append to %s: %s",
-                                   logfile->buf, strerror(errno));
-                       return -1;
-               }
-       }
-
-       adjust_shared_perm(logfile->buf);
-       close(logfd);
-       return 0;
-}
-
-
-int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
-{
-       int ret;
-       struct strbuf sb = STRBUF_INIT;
-
-       ret = log_ref_setup(refname, &sb, err, force_create);
-       strbuf_release(&sb);
-       return ret;
-}
-
-static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
-                           const unsigned char *new_sha1,
-                           const char *committer, const char *msg)
-{
-       int msglen, written;
-       unsigned maxlen, len;
-       char *logrec;
-
-       msglen = msg ? strlen(msg) : 0;
-       maxlen = strlen(committer) + msglen + 100;
-       logrec = xmalloc(maxlen);
-       len = xsnprintf(logrec, maxlen, "%s %s %s\n",
-                       sha1_to_hex(old_sha1),
-                       sha1_to_hex(new_sha1),
-                       committer);
-       if (msglen)
-               len += copy_reflog_msg(logrec + len - 1, msg) - 1;
-
-       written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
-       free(logrec);
-       if (written != len)
-               return -1;
-
-       return 0;
-}
-
-static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
-                          const unsigned char *new_sha1, const char *msg,
-                          struct strbuf *logfile, int flags,
-                          struct strbuf *err)
-{
-       int logfd, result, oflags = O_APPEND | O_WRONLY;
-
-       if (log_all_ref_updates < 0)
-               log_all_ref_updates = !is_bare_repository();
-
-       result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
-
-       if (result)
-               return result;
-
-       logfd = open(logfile->buf, oflags);
-       if (logfd < 0)
-               return 0;
-       result = log_ref_write_fd(logfd, old_sha1, new_sha1,
-                                 git_committer_info(0), msg);
-       if (result) {
-               strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
-                           strerror(errno));
-               close(logfd);
-               return -1;
-       }
-       if (close(logfd)) {
-               strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
-                           strerror(errno));
-               return -1;
-       }
-       return 0;
-}
-
-static int log_ref_write(const char *refname, const unsigned char *old_sha1,
-                        const unsigned char *new_sha1, const char *msg,
-                        int flags, struct strbuf *err)
-{
-       struct strbuf sb = STRBUF_INIT;
-       int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
-                                 err);
-       strbuf_release(&sb);
-       return ret;
-}
-
-int is_branch(const char *refname)
-{
-       return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
-}
-
-/*
- * Write sha1 into the open lockfile, then close the lockfile. On
- * errors, rollback the lockfile, fill in *err and
- * return -1.
- */
-static int write_ref_to_lockfile(struct ref_lock *lock,
-                                const unsigned char *sha1, struct strbuf *err)
-{
-       static char term = '\n';
-       struct object *o;
-       int fd;
-
-       o = parse_object(sha1);
-       if (!o) {
-               strbuf_addf(err,
-                           "Trying to write ref %s with nonexistent object %s",
-                           lock->ref_name, sha1_to_hex(sha1));
-               unlock_ref(lock);
-               return -1;
-       }
-       if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
-               strbuf_addf(err,
-                           "Trying to write non-commit object %s to branch %s",
-                           sha1_to_hex(sha1), lock->ref_name);
-               unlock_ref(lock);
-               return -1;
-       }
-       fd = get_lock_file_fd(lock->lk);
-       if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
-           write_in_full(fd, &term, 1) != 1 ||
-           close_ref(lock) < 0) {
-               strbuf_addf(err,
-                           "Couldn't write %s", get_lock_file_path(lock->lk));
-               unlock_ref(lock);
-               return -1;
-       }
-       return 0;
-}
-
-/*
- * Commit a change to a loose reference that has already been written
- * to the loose reference lockfile. Also update the reflogs if
- * necessary, using the specified lockmsg (which can be NULL).
- */
-static int commit_ref_update(struct ref_lock *lock,
-                            const unsigned char *sha1, const char *logmsg,
-                            int flags, struct strbuf *err)
-{
-       clear_loose_ref_cache(&ref_cache);
-       if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0 ||
-           (strcmp(lock->ref_name, lock->orig_ref_name) &&
-            log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0)) {
-               char *old_msg = strbuf_detach(err, NULL);
-               strbuf_addf(err, "Cannot update the ref '%s': %s",
-                           lock->ref_name, old_msg);
-               free(old_msg);
-               unlock_ref(lock);
-               return -1;
-       }
-       if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
-               /*
-                * Special hack: If a branch is updated directly and HEAD
-                * points to it (may happen on the remote side of a push
-                * for example) then logically the HEAD reflog should be
-                * updated too.
-                * A generic solution implies reverse symref information,
-                * but finding all symrefs pointing to the given branch
-                * would be rather costly for this rare event (the direct
-                * update of a branch) to be worth it.  So let's cheat and
-                * check with HEAD only which should cover 99% of all usage
-                * scenarios (even 100% of the default ones).
-                */
-               unsigned char head_sha1[20];
-               int head_flag;
-               const char *head_ref;
-               head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
-                                             head_sha1, &head_flag);
-               if (head_ref && (head_flag & REF_ISSYMREF) &&
-                   !strcmp(head_ref, lock->ref_name)) {
-                       struct strbuf log_err = STRBUF_INIT;
-                       if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
-                                         logmsg, 0, &log_err)) {
-                               error("%s", log_err.buf);
-                               strbuf_release(&log_err);
-                       }
+               fd = hold_lock_file_for_update(&lock, filename,
+                                              LOCK_DIE_ON_ERROR);
+               if (fd < 0)
+                       die_errno(_("Could not open '%s' for writing"), filename);
+               if (read_ref(pseudoref, actual_old_sha1))
+                       die("could not read ref '%s'", pseudoref);
+               if (hashcmp(actual_old_sha1, old_sha1)) {
+                       warning("Unexpected sha1 when deleting %s", pseudoref);
+                       rollback_lock_file(&lock);
+                       return -1;
                }
-       }
-       if (commit_ref(lock)) {
-               error("Couldn't set %s", lock->ref_name);
-               unlock_ref(lock);
-               return -1;
+
+               unlink(filename);
+               rollback_lock_file(&lock);
+       } else {
+               unlink(filename);
        }
 
-       unlock_ref(lock);
        return 0;
 }
 
-int create_symref(const char *ref_target, const char *refs_heads_master,
-                 const char *logmsg)
+int delete_ref(const char *refname, const unsigned char *old_sha1,
+              unsigned int flags)
 {
-       char *lockpath = NULL;
-       char ref[1000];
-       int fd, len, written;
-       char *git_HEAD = git_pathdup("%s", ref_target);
-       unsigned char old_sha1[20], new_sha1[20];
+       struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
 
-       if (logmsg && read_ref(ref_target, old_sha1))
-               hashclr(old_sha1);
-
-       if (safe_create_leading_directories(git_HEAD) < 0)
-               return error("unable to create directory for %s", git_HEAD);
+       if (ref_type(refname) == REF_TYPE_PSEUDOREF)
+               return delete_pseudoref(refname, old_sha1);
 
-#ifndef NO_SYMLINK_HEAD
-       if (prefer_symlink_refs) {
-               unlink(git_HEAD);
-               if (!symlink(refs_heads_master, git_HEAD))
-                       goto done;
-               fprintf(stderr, "no symlink - falling back to symbolic ref\n");
+       transaction = ref_transaction_begin(&err);
+       if (!transaction ||
+           ref_transaction_delete(transaction, refname, old_sha1,
+                                  flags, NULL, &err) ||
+           ref_transaction_commit(transaction, &err)) {
+               error("%s", err.buf);
+               ref_transaction_free(transaction);
+               strbuf_release(&err);
+               return 1;
        }
-#endif
+       ref_transaction_free(transaction);
+       strbuf_release(&err);
+       return 0;
+}
 
-       len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
-       if (sizeof(ref) <= len) {
-               error("refname too long: %s", refs_heads_master);
-               goto error_free_return;
-       }
-       lockpath = mkpathdup("%s.lock", git_HEAD);
-       fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
-       if (fd < 0) {
-               error("Unable to open %s for writing", lockpath);
-               goto error_free_return;
-       }
-       written = write_in_full(fd, ref, len);
-       if (close(fd) != 0 || written != len) {
-               error("Unable to write to %s", lockpath);
-               goto error_unlink_return;
-       }
-       if (rename(lockpath, git_HEAD) < 0) {
-               error("Unable to create %s", git_HEAD);
-               goto error_unlink_return;
-       }
-       if (adjust_shared_perm(git_HEAD)) {
-               error("Unable to fix permissions on %s", lockpath);
-       error_unlink_return:
-               unlink_or_warn(lockpath);
-       error_free_return:
-               free(lockpath);
-               free(git_HEAD);
-               return -1;
-       }
-       free(lockpath);
+int copy_reflog_msg(char *buf, const char *msg)
+{
+       char *cp = buf;
+       char c;
+       int wasspace = 1;
 
-#ifndef NO_SYMLINK_HEAD
-       done:
-#endif
-       if (logmsg && !read_ref(refs_heads_master, new_sha1) &&
-               log_ref_write(ref_target, old_sha1, new_sha1, logmsg, 0, &err)) {
-               error("%s", err.buf);
-               strbuf_release(&err);
+       *cp++ = '\t';
+       while ((c = *msg++)) {
+               if (wasspace && isspace(c))
+                       continue;
+               wasspace = isspace(c);
+               if (wasspace)
+                       c = ' ';
+               *cp++ = c;
        }
+       while (buf < cp && isspace(cp[-1]))
+               cp--;
+       *cp++ = '\n';
+       return cp - buf;
+}
 
-       free(git_HEAD);
-       return 0;
+int should_autocreate_reflog(const char *refname)
+{
+       if (!log_all_ref_updates)
+               return 0;
+       return starts_with(refname, "refs/heads/") ||
+               starts_with(refname, "refs/remotes/") ||
+               starts_with(refname, "refs/notes/") ||
+               !strcmp(refname, "HEAD");
+}
+
+int is_branch(const char *refname)
+{
+       return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 }
 
 struct read_ref_at_cb {
@@ -3735,287 +736,6 @@ int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time,
        return 1;
 }
 
-int reflog_exists(const char *refname)
-{
-       struct stat st;
-
-       return !lstat(git_path("logs/%s", refname), &st) &&
-               S_ISREG(st.st_mode);
-}
-
-int delete_reflog(const char *refname)
-{
-       return remove_path(git_path("logs/%s", refname));
-}
-
-static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
-{
-       unsigned char osha1[20], nsha1[20];
-       char *email_end, *message;
-       unsigned long timestamp;
-       int tz;
-
-       /* old SP new SP name <email> SP time TAB msg LF */
-       if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
-           get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
-           get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
-           !(email_end = strchr(sb->buf + 82, '>')) ||
-           email_end[1] != ' ' ||
-           !(timestamp = strtoul(email_end + 2, &message, 10)) ||
-           !message || message[0] != ' ' ||
-           (message[1] != '+' && message[1] != '-') ||
-           !isdigit(message[2]) || !isdigit(message[3]) ||
-           !isdigit(message[4]) || !isdigit(message[5]))
-               return 0; /* corrupt? */
-       email_end[1] = '\0';
-       tz = strtol(message + 1, NULL, 10);
-       if (message[6] != '\t')
-               message += 6;
-       else
-               message += 7;
-       return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
-}
-
-static char *find_beginning_of_line(char *bob, char *scan)
-{
-       while (bob < scan && *(--scan) != '\n')
-               ; /* keep scanning backwards */
-       /*
-        * Return either beginning of the buffer, or LF at the end of
-        * the previous line.
-        */
-       return scan;
-}
-
-int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
-{
-       struct strbuf sb = STRBUF_INIT;
-       FILE *logfp;
-       long pos;
-       int ret = 0, at_tail = 1;
-
-       logfp = fopen(git_path("logs/%s", refname), "r");
-       if (!logfp)
-               return -1;
-
-       /* Jump to the end */
-       if (fseek(logfp, 0, SEEK_END) < 0)
-               return error("cannot seek back reflog for %s: %s",
-                            refname, strerror(errno));
-       pos = ftell(logfp);
-       while (!ret && 0 < pos) {
-               int cnt;
-               size_t nread;
-               char buf[BUFSIZ];
-               char *endp, *scanp;
-
-               /* Fill next block from the end */
-               cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
-               if (fseek(logfp, pos - cnt, SEEK_SET))
-                       return error("cannot seek back reflog for %s: %s",
-                                    refname, strerror(errno));
-               nread = fread(buf, cnt, 1, logfp);
-               if (nread != 1)
-                       return error("cannot read %d bytes from reflog for %s: %s",
-                                    cnt, refname, strerror(errno));
-               pos -= cnt;
-
-               scanp = endp = buf + cnt;
-               if (at_tail && scanp[-1] == '\n')
-                       /* Looking at the final LF at the end of the file */
-                       scanp--;
-               at_tail = 0;
-
-               while (buf < scanp) {
-                       /*
-                        * terminating LF of the previous line, or the beginning
-                        * of the buffer.
-                        */
-                       char *bp;
-
-                       bp = find_beginning_of_line(buf, scanp);
-
-                       if (*bp == '\n') {
-                               /*
-                                * The newline is the end of the previous line,
-                                * so we know we have complete line starting
-                                * at (bp + 1). Prefix it onto any prior data
-                                * we collected for the line and process it.
-                                */
-                               strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
-                               scanp = bp;
-                               endp = bp + 1;
-                               ret = show_one_reflog_ent(&sb, fn, cb_data);
-                               strbuf_reset(&sb);
-                               if (ret)
-                                       break;
-                       } else if (!pos) {
-                               /*
-                                * We are at the start of the buffer, and the
-                                * start of the file; there is no previous
-                                * line, and we have everything for this one.
-                                * Process it, and we can end the loop.
-                                */
-                               strbuf_splice(&sb, 0, 0, buf, endp - buf);
-                               ret = show_one_reflog_ent(&sb, fn, cb_data);
-                               strbuf_reset(&sb);
-                               break;
-                       }
-
-                       if (bp == buf) {
-                               /*
-                                * We are at the start of the buffer, and there
-                                * is more file to read backwards. Which means
-                                * we are in the middle of a line. Note that we
-                                * may get here even if *bp was a newline; that
-                                * just means we are at the exact end of the
-                                * previous line, rather than some spot in the
-                                * middle.
-                                *
-                                * Save away what we have to be combined with
-                                * the data from the next read.
-                                */
-                               strbuf_splice(&sb, 0, 0, buf, endp - buf);
-                               break;
-                       }
-               }
-
-       }
-       if (!ret && sb.len)
-               die("BUG: reverse reflog parser had leftover data");
-
-       fclose(logfp);
-       strbuf_release(&sb);
-       return ret;
-}
-
-int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
-{
-       FILE *logfp;
-       struct strbuf sb = STRBUF_INIT;
-       int ret = 0;
-
-       logfp = fopen(git_path("logs/%s", refname), "r");
-       if (!logfp)
-               return -1;
-
-       while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
-               ret = show_one_reflog_ent(&sb, fn, cb_data);
-       fclose(logfp);
-       strbuf_release(&sb);
-       return ret;
-}
-/*
- * Call fn for each reflog in the namespace indicated by name.  name
- * must be empty or end with '/'.  Name will be used as a scratch
- * space, but its contents will be restored before return.
- */
-static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
-{
-       DIR *d = opendir(git_path("logs/%s", name->buf));
-       int retval = 0;
-       struct dirent *de;
-       int oldlen = name->len;
-
-       if (!d)
-               return name->len ? errno : 0;
-
-       while ((de = readdir(d)) != NULL) {
-               struct stat st;
-
-               if (de->d_name[0] == '.')
-                       continue;
-               if (ends_with(de->d_name, ".lock"))
-                       continue;
-               strbuf_addstr(name, de->d_name);
-               if (stat(git_path("logs/%s", name->buf), &st) < 0) {
-                       ; /* silently ignore */
-               } else {
-                       if (S_ISDIR(st.st_mode)) {
-                               strbuf_addch(name, '/');
-                               retval = do_for_each_reflog(name, fn, cb_data);
-                       } else {
-                               struct object_id oid;
-
-                               if (read_ref_full(name->buf, 0, oid.hash, NULL))
-                                       retval = error("bad ref for %s", name->buf);
-                               else
-                                       retval = fn(name->buf, &oid, 0, cb_data);
-                       }
-                       if (retval)
-                               break;
-               }
-               strbuf_setlen(name, oldlen);
-       }
-       closedir(d);
-       return retval;
-}
-
-int for_each_reflog(each_ref_fn fn, void *cb_data)
-{
-       int retval;
-       struct strbuf name;
-       strbuf_init(&name, PATH_MAX);
-       retval = do_for_each_reflog(&name, fn, cb_data);
-       strbuf_release(&name);
-       return retval;
-}
-
-/**
- * Information needed for a single ref update. Set new_sha1 to the new
- * value or to null_sha1 to delete the ref. To check the old value
- * while the ref is locked, set (flags & REF_HAVE_OLD) and set
- * old_sha1 to the old value, or to null_sha1 to ensure the ref does
- * not exist before update.
- */
-struct ref_update {
-       /*
-        * If (flags & REF_HAVE_NEW), set the reference to this value:
-        */
-       unsigned char new_sha1[20];
-       /*
-        * If (flags & REF_HAVE_OLD), check that the reference
-        * previously had this value:
-        */
-       unsigned char old_sha1[20];
-       /*
-        * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
-        * REF_DELETING, and REF_ISPRUNING:
-        */
-       unsigned int flags;
-       struct ref_lock *lock;
-       int type;
-       char *msg;
-       const char refname[FLEX_ARRAY];
-};
-
-/*
- * Transaction states.
- * OPEN:   The transaction is in a valid state and can accept new updates.
- *         An OPEN transaction can be committed.
- * CLOSED: A closed transaction is no longer active and no other operations
- *         than free can be used on it in this state.
- *         A transaction can either become closed by successfully committing
- *         an active transaction or if there is a failure while building
- *         the transaction thus rendering it failed/inactive.
- */
-enum ref_transaction_state {
-       REF_TRANSACTION_OPEN   = 0,
-       REF_TRANSACTION_CLOSED = 1
-};
-
-/*
- * Data structure for holding a reference transaction, which can
- * consist of checks and updates to multiple references, carried out
- * as atomically as possible.  This structure is opaque to callers.
- */
-struct ref_transaction {
-       struct ref_update **updates;
-       size_t alloc;
-       size_t nr;
-       enum ref_transaction_state state;
-};
-
 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 {
        assert(err);
@@ -4166,269 +886,6 @@ int update_ref(const char *msg, const char *refname,
        return 0;
 }
 
-static int ref_update_reject_duplicates(struct string_list *refnames,
-                                       struct strbuf *err)
-{
-       int i, n = refnames->nr;
-
-       assert(err);
-
-       for (i = 1; i < n; i++)
-               if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
-                       strbuf_addf(err,
-                                   "Multiple updates for ref '%s' not allowed.",
-                                   refnames->items[i].string);
-                       return 1;
-               }
-       return 0;
-}
-
-int ref_transaction_commit(struct ref_transaction *transaction,
-                          struct strbuf *err)
-{
-       int ret = 0, i;
-       int n = transaction->nr;
-       struct ref_update **updates = transaction->updates;
-       struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
-       struct string_list_item *ref_to_delete;
-       struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-
-       assert(err);
-
-       if (transaction->state != REF_TRANSACTION_OPEN)
-               die("BUG: commit called for transaction that is not open");
-
-       if (!n) {
-               transaction->state = REF_TRANSACTION_CLOSED;
-               return 0;
-       }
-
-       /* Fail if a refname appears more than once in the transaction: */
-       for (i = 0; i < n; i++)
-               string_list_append(&affected_refnames, updates[i]->refname);
-       string_list_sort(&affected_refnames);
-       if (ref_update_reject_duplicates(&affected_refnames, err)) {
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-
-       /*
-        * Acquire all locks, verify old values if provided, check
-        * that new values are valid, and write new values to the
-        * lockfiles, ready to be activated. Only keep one lockfile
-        * open at a time to avoid running out of file descriptors.
-        */
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-
-               if ((update->flags & REF_HAVE_NEW) &&
-                   is_null_sha1(update->new_sha1))
-                       update->flags |= REF_DELETING;
-               update->lock = lock_ref_sha1_basic(
-                               update->refname,
-                               ((update->flags & REF_HAVE_OLD) ?
-                                update->old_sha1 : NULL),
-                               &affected_refnames, NULL,
-                               update->flags,
-                               &update->type,
-                               err);
-               if (!update->lock) {
-                       char *reason;
-
-                       ret = (errno == ENOTDIR)
-                               ? TRANSACTION_NAME_CONFLICT
-                               : TRANSACTION_GENERIC_ERROR;
-                       reason = strbuf_detach(err, NULL);
-                       strbuf_addf(err, "cannot lock ref '%s': %s",
-                                   update->refname, reason);
-                       free(reason);
-                       goto cleanup;
-               }
-               if ((update->flags & REF_HAVE_NEW) &&
-                   !(update->flags & REF_DELETING)) {
-                       int overwriting_symref = ((update->type & REF_ISSYMREF) &&
-                                                 (update->flags & REF_NODEREF));
-
-                       if (!overwriting_symref &&
-                           !hashcmp(update->lock->old_oid.hash, update->new_sha1)) {
-                               /*
-                                * The reference already has the desired
-                                * value, so we don't need to write it.
-                                */
-                       } else if (write_ref_to_lockfile(update->lock,
-                                                        update->new_sha1,
-                                                        err)) {
-                               char *write_err = strbuf_detach(err, NULL);
-
-                               /*
-                                * The lock was freed upon failure of
-                                * write_ref_to_lockfile():
-                                */
-                               update->lock = NULL;
-                               strbuf_addf(err,
-                                           "cannot update the ref '%s': %s",
-                                           update->refname, write_err);
-                               free(write_err);
-                               ret = TRANSACTION_GENERIC_ERROR;
-                               goto cleanup;
-                       } else {
-                               update->flags |= REF_NEEDS_COMMIT;
-                       }
-               }
-               if (!(update->flags & REF_NEEDS_COMMIT)) {
-                       /*
-                        * We didn't have to write anything to the lockfile.
-                        * Close it to free up the file descriptor:
-                        */
-                       if (close_ref(update->lock)) {
-                               strbuf_addf(err, "Couldn't close %s.lock",
-                                           update->refname);
-                               goto cleanup;
-                       }
-               }
-       }
-
-       /* Perform updates first so live commits remain referenced */
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-
-               if (update->flags & REF_NEEDS_COMMIT) {
-                       if (commit_ref_update(update->lock,
-                                             update->new_sha1, update->msg,
-                                             update->flags, err)) {
-                               /* freed by commit_ref_update(): */
-                               update->lock = NULL;
-                               ret = TRANSACTION_GENERIC_ERROR;
-                               goto cleanup;
-                       } else {
-                               /* freed by commit_ref_update(): */
-                               update->lock = NULL;
-                       }
-               }
-       }
-
-       /* Perform deletes now that updates are safely completed */
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-
-               if (update->flags & REF_DELETING) {
-                       if (delete_ref_loose(update->lock, update->type, err)) {
-                               ret = TRANSACTION_GENERIC_ERROR;
-                               goto cleanup;
-                       }
-
-                       if (!(update->flags & REF_ISPRUNING))
-                               string_list_append(&refs_to_delete,
-                                                  update->lock->ref_name);
-               }
-       }
-
-       if (repack_without_refs(&refs_to_delete, err)) {
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-       for_each_string_list_item(ref_to_delete, &refs_to_delete)
-               unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
-       clear_loose_ref_cache(&ref_cache);
-
-cleanup:
-       transaction->state = REF_TRANSACTION_CLOSED;
-
-       for (i = 0; i < n; i++)
-               if (updates[i]->lock)
-                       unlock_ref(updates[i]->lock);
-       string_list_clear(&refs_to_delete, 0);
-       string_list_clear(&affected_refnames, 0);
-       return ret;
-}
-
-static int ref_present(const char *refname,
-                      const struct object_id *oid, int flags, void *cb_data)
-{
-       struct string_list *affected_refnames = cb_data;
-
-       return string_list_has_string(affected_refnames, refname);
-}
-
-int initial_ref_transaction_commit(struct ref_transaction *transaction,
-                                  struct strbuf *err)
-{
-       int ret = 0, i;
-       int n = transaction->nr;
-       struct ref_update **updates = transaction->updates;
-       struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-
-       assert(err);
-
-       if (transaction->state != REF_TRANSACTION_OPEN)
-               die("BUG: commit called for transaction that is not open");
-
-       /* Fail if a refname appears more than once in the transaction: */
-       for (i = 0; i < n; i++)
-               string_list_append(&affected_refnames, updates[i]->refname);
-       string_list_sort(&affected_refnames);
-       if (ref_update_reject_duplicates(&affected_refnames, err)) {
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-
-       /*
-        * It's really undefined to call this function in an active
-        * repository or when there are existing references: we are
-        * only locking and changing packed-refs, so (1) any
-        * simultaneous processes might try to change a reference at
-        * the same time we do, and (2) any existing loose versions of
-        * the references that we are setting would have precedence
-        * over our values. But some remote helpers create the remote
-        * "HEAD" and "master" branches before calling this function,
-        * so here we really only check that none of the references
-        * that we are creating already exists.
-        */
-       if (for_each_rawref(ref_present, &affected_refnames))
-               die("BUG: initial ref transaction called with existing refs");
-
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-
-               if ((update->flags & REF_HAVE_OLD) &&
-                   !is_null_sha1(update->old_sha1))
-                       die("BUG: initial ref transaction with old_sha1 set");
-               if (verify_refname_available(update->refname,
-                                            &affected_refnames, NULL,
-                                            err)) {
-                       ret = TRANSACTION_NAME_CONFLICT;
-                       goto cleanup;
-               }
-       }
-
-       if (lock_packed_refs(0)) {
-               strbuf_addf(err, "unable to lock packed-refs file: %s",
-                           strerror(errno));
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-
-               if ((update->flags & REF_HAVE_NEW) &&
-                   !is_null_sha1(update->new_sha1))
-                       add_packed_ref(update->refname, update->new_sha1);
-       }
-
-       if (commit_packed_refs()) {
-               strbuf_addf(err, "unable to commit packed-refs file: %s",
-                           strerror(errno));
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-
-cleanup:
-       transaction->state = REF_TRANSACTION_CLOSED;
-       string_list_clear(&affected_refnames, 0);
-       return ret;
-}
-
 char *shorten_unambiguous_ref(const char *refname, int strict)
 {
        int i;
@@ -4548,7 +1005,7 @@ int parse_hide_refs_config(const char *var, const char *value, const char *secti
        return 0;
 }
 
-int ref_is_hidden(const char *refname)
+int ref_is_hidden(const char *refname, const char *refname_full)
 {
        int i;
 
@@ -4556,6 +1013,7 @@ int ref_is_hidden(const char *refname)
                return 0;
        for (i = hide_refs->nr - 1; i >= 0; i--) {
                const char *match = hide_refs->items[i].string;
+               const char *subject;
                int neg = 0;
                int len;
 
@@ -4564,153 +1022,63 @@ int ref_is_hidden(const char *refname)
                        match++;
                }
 
-               if (!starts_with(refname, match))
+               if (*match == '^') {
+                       subject = refname_full;
+                       match++;
+               } else {
+                       subject = refname;
+               }
+
+               /* refname can be NULL when namespaces are used. */
+               if (!subject || !starts_with(subject, match))
                        continue;
                len = strlen(match);
-               if (!refname[len] || refname[len] == '/')
+               if (!subject[len] || subject[len] == '/')
                        return !neg;
        }
        return 0;
 }
 
-struct expire_reflog_cb {
-       unsigned int flags;
-       reflog_expiry_should_prune_fn *should_prune_fn;
-       void *policy_cb;
-       FILE *newlog;
-       unsigned char last_kept_sha1[20];
-};
-
-static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-                            const char *email, unsigned long timestamp, int tz,
-                            const char *message, void *cb_data)
-{
-       struct expire_reflog_cb *cb = cb_data;
-       struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
-
-       if (cb->flags & EXPIRE_REFLOGS_REWRITE)
-               osha1 = cb->last_kept_sha1;
-
-       if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
-                                  message, policy_cb)) {
-               if (!cb->newlog)
-                       printf("would prune %s", message);
-               else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-                       printf("prune %s", message);
-       } else {
-               if (cb->newlog) {
-                       fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
-                               sha1_to_hex(osha1), sha1_to_hex(nsha1),
-                               email, timestamp, tz, message);
-                       hashcpy(cb->last_kept_sha1, nsha1);
-               }
-               if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-                       printf("keep %s", message);
-       }
-       return 0;
-}
-
-int reflog_expire(const char *refname, const unsigned char *sha1,
-                unsigned int flags,
-                reflog_expiry_prepare_fn prepare_fn,
-                reflog_expiry_should_prune_fn should_prune_fn,
-                reflog_expiry_cleanup_fn cleanup_fn,
-                void *policy_cb_data)
+const char *find_descendant_ref(const char *dirname,
+                               const struct string_list *extras,
+                               const struct string_list *skip)
 {
-       static struct lock_file reflog_lock;
-       struct expire_reflog_cb cb;
-       struct ref_lock *lock;
-       char *log_file;
-       int status = 0;
-       int type;
-       struct strbuf err = STRBUF_INIT;
+       int pos;
 
-       memset(&cb, 0, sizeof(cb));
-       cb.flags = flags;
-       cb.policy_cb = policy_cb_data;
-       cb.should_prune_fn = should_prune_fn;
+       if (!extras)
+               return NULL;
 
        /*
-        * The reflog file is locked by holding the lock on the
-        * reference itself, plus we might need to update the
-        * reference if --updateref was specified:
+        * Look at the place where dirname would be inserted into
+        * extras. If there is an entry at that position that starts
+        * with dirname (remember, dirname includes the trailing
+        * slash) and is not in skip, then we have a conflict.
         */
-       lock = lock_ref_sha1_basic(refname, sha1, NULL, NULL, 0, &type, &err);
-       if (!lock) {
-               error("cannot lock ref '%s': %s", refname, err.buf);
-               strbuf_release(&err);
-               return -1;
-       }
-       if (!reflog_exists(refname)) {
-               unlock_ref(lock);
-               return 0;
-       }
+       for (pos = string_list_find_insert_index(extras, dirname, 0);
+            pos < extras->nr; pos++) {
+               const char *extra_refname = extras->items[pos].string;
 
-       log_file = git_pathdup("logs/%s", refname);
-       if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-               /*
-                * Even though holding $GIT_DIR/logs/$reflog.lock has
-                * no locking implications, we use the lock_file
-                * machinery here anyway because it does a lot of the
-                * work we need, including cleaning up if the program
-                * exits unexpectedly.
-                */
-               if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
-                       struct strbuf err = STRBUF_INIT;
-                       unable_to_lock_message(log_file, errno, &err);
-                       error("%s", err.buf);
-                       strbuf_release(&err);
-                       goto failure;
-               }
-               cb.newlog = fdopen_lock_file(&reflog_lock, "w");
-               if (!cb.newlog) {
-                       error("cannot fdopen %s (%s)",
-                             get_lock_file_path(&reflog_lock), strerror(errno));
-                       goto failure;
-               }
+               if (!starts_with(extra_refname, dirname))
+                       break;
+
+               if (!skip || !string_list_has_string(skip, extra_refname))
+                       return extra_refname;
        }
+       return NULL;
+}
+
+int rename_ref_available(const char *oldname, const char *newname)
+{
+       struct string_list skip = STRING_LIST_INIT_NODUP;
+       struct strbuf err = STRBUF_INIT;
+       int ret;
 
-       (*prepare_fn)(refname, sha1, cb.policy_cb);
-       for_each_reflog_ent(refname, expire_reflog_ent, &cb);
-       (*cleanup_fn)(cb.policy_cb);
+       string_list_insert(&skip, oldname);
+       ret = !verify_refname_available(newname, NULL, &skip, &err);
+       if (!ret)
+               error("%s", err.buf);
 
-       if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-               /*
-                * It doesn't make sense to adjust a reference pointed
-                * to by a symbolic ref based on expiring entries in
-                * the symbolic reference's reflog. Nor can we update
-                * a reference if there are no remaining reflog
-                * entries.
-                */
-               int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
-                       !(type & REF_ISSYMREF) &&
-                       !is_null_sha1(cb.last_kept_sha1);
-
-               if (close_lock_file(&reflog_lock)) {
-                       status |= error("couldn't write %s: %s", log_file,
-                                       strerror(errno));
-               } else if (update &&
-                          (write_in_full(get_lock_file_fd(lock->lk),
-                               sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
-                           write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
-                           close_ref(lock) < 0)) {
-                       status |= error("couldn't write %s",
-                                       get_lock_file_path(lock->lk));
-                       rollback_lock_file(&reflog_lock);
-               } else if (commit_lock_file(&reflog_lock)) {
-                       status |= error("unable to commit reflog '%s' (%s)",
-                                       log_file, strerror(errno));
-               } else if (update && commit_ref(lock)) {
-                       status |= error("couldn't set %s", lock->ref_name);
-               }
-       }
-       free(log_file);
-       unlock_ref(lock);
-       return status;
-
- failure:
-       rollback_lock_file(&reflog_lock);
-       free(log_file);
-       unlock_ref(lock);
-       return -1;
+       string_list_clear(&skip, 0);
+       strbuf_release(&err);
+       return ret;
 }