parse-options: remove unused OPT_SET_PTR
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index 60f250769ed2665f7103f519e04594819f3501d5..89228e23732ef7e2e83a2e84e82ffb5bd7afec3f 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -634,18 +634,22 @@ struct ref_entry_cb {
 static int do_one_ref(struct ref_entry *entry, void *cb_data)
 {
        struct ref_entry_cb *data = cb_data;
+       struct ref_entry *old_current_ref;
        int retval;
-       if (prefixcmp(entry->name, data->base))
+
+       if (!starts_with(entry->name, data->base))
                return 0;
 
        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
              !ref_resolves_to_object(entry))
                return 0;
 
+       /* 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.sha1,
                          entry->flag, data->cb_data);
-       current_ref = NULL;
+       current_ref = old_current_ref;
        return retval;
 }
 
@@ -749,6 +753,21 @@ static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
        }
 }
 
+/*
+ * 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)
+{
+       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 true iff refname1 and refname2 conflict with each other.
  * Two reference names conflict if one of them exactly matches the
@@ -928,13 +947,6 @@ static struct ref_cache *get_ref_cache(const char *submodule)
        return refs;
 }
 
-void invalidate_ref_cache(const char *submodule)
-{
-       struct ref_cache *refs = get_ref_cache(submodule);
-       clear_packed_ref_cache(refs);
-       clear_loose_ref_cache(refs);
-}
-
 /* The length of a peeled reference line in packed-refs, including EOL: */
 #define PEELED_LINE_LENGTH 42
 
@@ -1030,7 +1042,7 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
                if (refname) {
                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
                        if (peeled == PEELED_FULLY ||
-                           (peeled == PEELED_TAGS && !prefixcmp(refname, "refs/tags/")))
+                           (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
                                last->flag |= REF_KNOWS_PEELED;
                        add_ref(dir, last);
                        continue;
@@ -1280,6 +1292,37 @@ 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 const char *handle_missing_loose_ref(const char *refname,
+                                           unsigned char *sha1,
+                                           int reading,
+                                           int *flag)
+{
+       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.sha1);
+               if (flag)
+                       *flag |= REF_ISPACKED;
+               return refname;
+       }
+       /* The reference is not a packed reference, either. */
+       if (reading) {
+               return NULL;
+       } else {
+               hashclr(sha1);
+               return refname;
+       }
+}
+
 const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
 {
        int depth = MAXDEPTH;
@@ -1304,38 +1347,36 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
 
                git_snpath(path, sizeof(path), "%s", refname);
 
+               /*
+                * 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) {
-                       struct ref_entry *entry;
-
-                       if (errno != ENOENT)
-                               return NULL;
-                       /*
-                        * The loose reference file does not exist;
-                        * check for a packed reference.
-                        */
-                       entry = get_packed_ref(refname);
-                       if (entry) {
-                               hashcpy(sha1, entry->u.value.sha1);
-                               if (flag)
-                                       *flag |= REF_ISPACKED;
-                               return refname;
-                       }
-                       /* The reference is not a packed reference, either. */
-                       if (reading) {
+                       if (errno == ENOENT)
+                               return handle_missing_loose_ref(refname, sha1,
+                                                               reading, flag);
+                       else
                                return NULL;
-                       } else {
-                               hashclr(sha1);
-                               return refname;
-                       }
                }
 
                /* Follow "normalized" - ie "refs/.." symlinks by hand */
                if (S_ISLNK(st.st_mode)) {
                        len = readlink(path, buffer, sizeof(buffer)-1);
-                       if (len < 0)
-                               return NULL;
+                       if (len < 0) {
+                               if (errno == ENOENT || errno == EINVAL)
+                                       /* inconsistent with lstat; retry */
+                                       goto stat_ref;
+                               else
+                                       return NULL;
+                       }
                        buffer[len] = 0;
-                       if (!prefixcmp(buffer, "refs/") &&
+                       if (starts_with(buffer, "refs/") &&
                                        !check_refname_format(buffer, 0)) {
                                strcpy(refname_buffer, buffer);
                                refname = refname_buffer;
@@ -1356,8 +1397,13 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                 * a ref
                 */
                fd = open(path, O_RDONLY);
-               if (fd < 0)
-                       return NULL;
+               if (fd < 0) {
+                       if (errno == ENOENT)
+                               /* inconsistent with lstat; retry */
+                               goto stat_ref;
+                       else
+                               return NULL;
+               }
                len = read_in_full(fd, buffer, sizeof(buffer)-1);
                close(fd);
                if (len < 0)
@@ -1369,8 +1415,19 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                /*
                 * Is it a symbolic ref?
                 */
-               if (prefixcmp(buffer, "ref:"))
-                       break;
+               if (!starts_with(buffer, "ref:")) {
+                       /*
+                        * Please note that FETCH_HEAD has a second
+                        * line containing other data.
+                        */
+                       if (get_sha1_hex(buffer, sha1) ||
+                           (buffer[40] != '\0' && !isspace(buffer[40]))) {
+                               if (flag)
+                                       *flag |= REF_ISBROKEN;
+                               return NULL;
+                       }
+                       return refname;
+               }
                if (flag)
                        *flag |= REF_ISSYMREF;
                buf = buffer + 4;
@@ -1383,13 +1440,6 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                }
                refname = strcpy(refname_buffer, buf);
        }
-       /* Please note that FETCH_HEAD has a second line containing other data. */
-       if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
-               if (flag)
-                       *flag |= REF_ISBROKEN;
-               return NULL;
-       }
-       return refname;
 }
 
 char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
@@ -1603,15 +1653,31 @@ void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 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 = get_packed_ref_cache(refs);
-       struct ref_dir *packed_dir = get_packed_ref_dir(packed_ref_cache);
-       struct ref_dir *loose_dir = get_loose_refs(refs);
+       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);
-               loose_dir = find_containing_dir(loose_dir, base, 0);
        }
 
        if (packed_dir && loose_dir) {
@@ -1771,7 +1837,7 @@ int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
        struct ref_filter filter;
        int ret;
 
-       if (!prefix && prefixcmp(pattern, "refs/"))
+       if (!prefix && !starts_with(pattern, "refs/"))
                strbuf_addstr(&real_pattern, "refs/");
        else if (prefix)
                strbuf_addstr(&real_pattern, prefix);
@@ -1808,13 +1874,13 @@ int for_each_rawref(each_ref_fn fn, void *cb_data)
 const char *prettify_refname(const char *name)
 {
        return name + (
-               !prefixcmp(name, "refs/heads/") ? 11 :
-               !prefixcmp(name, "refs/tags/") ? 10 :
-               !prefixcmp(name, "refs/remotes/") ? 13 :
+               starts_with(name, "refs/heads/") ? 11 :
+               starts_with(name, "refs/tags/") ? 10 :
+               starts_with(name, "refs/remotes/") ? 13 :
                0);
 }
 
-const char *ref_rev_parse_rules[] = {
+static const char *ref_rev_parse_rules[] = {
        "%.*s",
        "refs/%.*s",
        "refs/tags/%.*s",
@@ -1824,12 +1890,12 @@ const char *ref_rev_parse_rules[] = {
        NULL
 };
 
-int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
+int refname_match(const char *abbrev_name, const char *full_name)
 {
        const char **p;
        const int abbrev_name_len = strlen(abbrev_name);
 
-       for (p = rules; *p; p++) {
+       for (p = ref_rev_parse_rules; *p; p++) {
                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
                        return 1;
                }
@@ -1882,7 +1948,7 @@ static int remove_empty_directories(const char *file)
 static char *substitute_branch_name(const char **string, int *len)
 {
        struct strbuf buf = STRBUF_INIT;
-       int ret = interpret_branch_name(*string, &buf);
+       int ret = interpret_branch_name(*string, *len, &buf);
 
        if (ret == *len) {
                size_t size;
@@ -1973,6 +2039,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        int type, lflags;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
        int missing = 0;
+       int attempts_remaining = 3;
 
        lock = xcalloc(1, sizeof(struct ref_lock));
        lock->lock_fd = -1;
@@ -2014,7 +2081,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
        lock->lk = xcalloc(1, sizeof(struct lock_file));
 
-       lflags = LOCK_DIE_ON_ERROR;
+       lflags = 0;
        if (flags & REF_NODEREF) {
                refname = orig_refname;
                lflags |= LOCK_NODEREF;
@@ -2027,13 +2094,32 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
                lock->force_write = 1;
 
-       if (safe_create_leading_directories(ref_file)) {
+ retry:
+       switch (safe_create_leading_directories(ref_file)) {
+       case SCLD_OK:
+               break; /* success */
+       case SCLD_VANISHED:
+               if (--attempts_remaining > 0)
+                       goto retry;
+               /* fall through */
+       default:
                last_errno = errno;
                error("unable to create directory for %s", ref_file);
                goto error_return;
        }
 
        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
+       if (lock->lock_fd < 0) {
+               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_index_die(ref_file, errno);
+       }
        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 
  error_return:
@@ -2052,11 +2138,12 @@ struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha
 }
 
 struct ref_lock *lock_any_ref_for_update(const char *refname,
-                                        const unsigned char *old_sha1, int flags)
+                                        const unsigned char *old_sha1,
+                                        int flags, int *type_p)
 {
        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
                return NULL;
-       return lock_ref_sha1_basic(refname, old_sha1, flags, NULL);
+       return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
 }
 
 /*
@@ -2105,11 +2192,14 @@ int lock_packed_refs(int flags)
 {
        struct packed_ref_cache *packed_ref_cache;
 
-       /* Discard the old cache because it might be invalid: */
-       clear_packed_ref_cache(&ref_cache);
        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
                return -1;
-       /* Read the current packed-refs while holding the lock: */
+       /*
+        * 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: */
@@ -2174,7 +2264,7 @@ 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 = !prefixcmp(entry->name, "refs/tags/");
+       int is_tag_ref = starts_with(entry->name, "refs/tags/");
 
        /* ALWAYS pack tags */
        if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
@@ -2341,60 +2431,82 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
        return 0;
 }
 
-static int repack_without_ref(const char *refname)
+static int repack_without_refs(const char **refnames, int n)
 {
        struct ref_dir *packed;
        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
        struct string_list_item *ref_to_delete;
+       int i, removed = 0;
+
+       /* Look for a packed ref */
+       for (i = 0; i < n; i++)
+               if (get_packed_ref(refnames[i]))
+                       break;
 
-       if (!get_packed_ref(refname))
-               return 0; /* refname does not exist in packed refs */
+       /* Avoid locking if we have nothing to do */
+       if (i == n)
+               return 0; /* no refname exists in packed refs */
 
        if (lock_packed_refs(0)) {
                unable_to_lock_error(git_path("packed-refs"), errno);
-               return error("cannot delete '%s' from packed refs", refname);
+               return error("cannot delete '%s' from packed refs", refnames[i]);
        }
        packed = get_packed_refs(&ref_cache);
 
-       /* Remove refname from the cache: */
-       if (remove_entry(packed, refname) == -1) {
+       /* Remove refnames from the cache */
+       for (i = 0; i < n; i++)
+               if (remove_entry(packed, refnames[i]) != -1)
+                       removed = 1;
+       if (!removed) {
                /*
-                * The packed entry disappeared while we were
+                * All packed entries disappeared while we were
                 * acquiring the lock.
                 */
                rollback_packed_refs();
                return 0;
        }
 
-       /* Remove any other accumulated cruft: */
+       /* Remove any other accumulated cruft */
        do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
        for_each_string_list_item(ref_to_delete, &refs_to_delete) {
                if (remove_entry(packed, ref_to_delete->string) == -1)
                        die("internal error");
        }
 
-       /* Write what remains: */
+       /* Write what remains */
        return commit_packed_refs();
 }
 
-int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
+static int repack_without_ref(const char *refname)
 {
-       struct ref_lock *lock;
-       int err, i = 0, ret = 0, flag = 0;
+       return repack_without_refs(&refname, 1);
+}
 
-       lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
-       if (!lock)
-               return 1;
+static int delete_ref_loose(struct ref_lock *lock, int flag)
+{
        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
                /* loose */
-               i = strlen(lock->lk->filename) - 5; /* .lock */
+               int err, i = strlen(lock->lk->filename) - 5; /* .lock */
+
                lock->lk->filename[i] = 0;
                err = unlink_or_warn(lock->lk->filename);
-               if (err && errno != ENOENT)
-                       ret = 1;
-
                lock->lk->filename[i] = '.';
+               if (err && errno != ENOENT)
+                       return 1;
        }
+       return 0;
+}
+
+int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
+{
+       struct ref_lock *lock;
+       int ret = 0, flag = 0;
+
+       lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
+       if (!lock)
+               return 1;
+       ret |= delete_ref_loose(lock, flag);
+
        /* removing the loose one could have resurrected an earlier
         * packed one.  Also, if it was not loose we need to repack
         * without it.
@@ -2416,6 +2528,51 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
  */
 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
 
+static int rename_tmp_log(const char *newrefname)
+{
+       int attempts_remaining = 4;
+
+ retry:
+       switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
+       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);
+               return -1;
+       }
+
+       if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
+               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(git_path("logs/%s", newrefname))) {
+                               error("Directory not empty: logs/%s", newrefname);
+                               return -1;
+                       }
+                       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));
+                       return -1;
+               }
+       }
+       return 0;
+}
+
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
        unsigned char sha1[20], orig_sha1[20];
@@ -2463,30 +2620,9 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
                }
        }
 
-       if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
-               error("unable to create directory for %s", newrefname);
+       if (log && rename_tmp_log(newrefname))
                goto rollback;
-       }
 
- retry:
-       if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
-               if (errno==EISDIR || errno==ENOTDIR) {
-                       /*
-                        * 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(git_path("logs/%s", newrefname))) {
-                               error("Directory not empty: logs/%s", newrefname);
-                               goto rollback;
-                       }
-                       goto retry;
-               } else {
-                       error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-                               newrefname, strerror(errno));
-                       goto rollback;
-               }
-       }
        logmoved = log;
 
        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
@@ -2587,9 +2723,9 @@ int log_ref_setup(const char *refname, char *logfile, int bufsize)
 
        git_snpath(logfile, bufsize, "logs/%s", refname);
        if (log_all_ref_updates &&
-           (!prefixcmp(refname, "refs/heads/") ||
-            !prefixcmp(refname, "refs/remotes/") ||
-            !prefixcmp(refname, "refs/notes/") ||
+           (starts_with(refname, "refs/heads/") ||
+            starts_with(refname, "refs/remotes/") ||
+            starts_with(refname, "refs/notes/") ||
             !strcmp(refname, "HEAD"))) {
                if (safe_create_leading_directories(logfile) < 0)
                        return error("unable to create directory for %s",
@@ -2659,7 +2795,7 @@ static int log_ref_write(const char *refname, const unsigned char *old_sha1,
 
 static int is_branch(const char *refname)
 {
-       return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
+       return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 }
 
 int write_ref_sha1(struct ref_lock *lock,
@@ -3097,12 +3233,13 @@ int for_each_reflog(each_ref_fn fn, void *cb_data)
        return retval;
 }
 
-int update_ref(const char *action, const char *refname,
-               const unsigned char *sha1, const unsigned char *oldval,
-               int flags, enum action_on_err onerr)
+static struct ref_lock *update_ref_lock(const char *refname,
+                                       const unsigned char *oldval,
+                                       int flags, int *type_p,
+                                       enum action_on_err onerr)
 {
-       static struct ref_lock *lock;
-       lock = lock_any_ref_for_update(refname, oldval, flags);
+       struct ref_lock *lock;
+       lock = lock_any_ref_for_update(refname, oldval, flags, type_p);
        if (!lock) {
                const char *str = "Cannot lock the ref '%s'.";
                switch (onerr) {
@@ -3110,8 +3247,14 @@ int update_ref(const char *action, const char *refname,
                case DIE_ON_ERR: die(str, refname); break;
                case QUIET_ON_ERR: break;
                }
-               return 1;
        }
+       return lock;
+}
+
+static int update_ref_write(const char *action, const char *refname,
+                           const unsigned char *sha1, struct ref_lock *lock,
+                           enum action_on_err onerr)
+{
        if (write_ref_sha1(lock, sha1, action) < 0) {
                const char *str = "Cannot update the ref '%s'.";
                switch (onerr) {
@@ -3124,35 +3267,115 @@ int update_ref(const char *action, const char *refname,
        return 0;
 }
 
-struct ref *find_ref_by_name(const struct ref *list, const char *name)
+int update_ref(const char *action, const char *refname,
+              const unsigned char *sha1, const unsigned char *oldval,
+              int flags, enum action_on_err onerr)
 {
-       for ( ; list; list = list->next)
-               if (!strcmp(list->name, name))
-                       return (struct ref *)list;
-       return NULL;
+       struct ref_lock *lock;
+       lock = update_ref_lock(refname, oldval, flags, NULL, onerr);
+       if (!lock)
+               return 1;
+       return update_ref_write(action, refname, sha1, lock, onerr);
 }
 
-/*
- * generate a format suitable for scanf from a ref_rev_parse_rules
- * rule, that is replace the "%.*s" spec with a "%s" spec
- */
-static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
+static int ref_update_compare(const void *r1, const void *r2)
+{
+       const struct ref_update * const *u1 = r1;
+       const struct ref_update * const *u2 = r2;
+       return strcmp((*u1)->ref_name, (*u2)->ref_name);
+}
+
+static int ref_update_reject_duplicates(struct ref_update **updates, int n,
+                                       enum action_on_err onerr)
 {
-       char *spec;
+       int i;
+       for (i = 1; i < n; i++)
+               if (!strcmp(updates[i - 1]->ref_name, updates[i]->ref_name)) {
+                       const char *str =
+                               "Multiple updates for ref '%s' not allowed.";
+                       switch (onerr) {
+                       case MSG_ON_ERR:
+                               error(str, updates[i]->ref_name); break;
+                       case DIE_ON_ERR:
+                               die(str, updates[i]->ref_name); break;
+                       case QUIET_ON_ERR:
+                               break;
+                       }
+                       return 1;
+               }
+       return 0;
+}
 
-       spec = strstr(rule, "%.*s");
-       if (!spec || strstr(spec + 4, "%.*s"))
-               die("invalid rule in ref_rev_parse_rules: %s", rule);
+int update_refs(const char *action, const struct ref_update **updates_orig,
+               int n, enum action_on_err onerr)
+{
+       int ret = 0, delnum = 0, i;
+       struct ref_update **updates;
+       int *types;
+       struct ref_lock **locks;
+       const char **delnames;
 
-       /* copy all until spec */
-       strncpy(scanf_fmt, rule, spec - rule);
-       scanf_fmt[spec - rule] = '\0';
-       /* copy new spec */
-       strcat(scanf_fmt, "%s");
-       /* copy remaining rule */
-       strcat(scanf_fmt, spec + 4);
+       if (!updates_orig || !n)
+               return 0;
 
-       return;
+       /* Allocate work space */
+       updates = xmalloc(sizeof(*updates) * n);
+       types = xmalloc(sizeof(*types) * n);
+       locks = xcalloc(n, sizeof(*locks));
+       delnames = xmalloc(sizeof(*delnames) * n);
+
+       /* Copy, sort, and reject duplicate refs */
+       memcpy(updates, updates_orig, sizeof(*updates) * n);
+       qsort(updates, n, sizeof(*updates), ref_update_compare);
+       ret = ref_update_reject_duplicates(updates, n, onerr);
+       if (ret)
+               goto cleanup;
+
+       /* Acquire all locks while verifying old values */
+       for (i = 0; i < n; i++) {
+               locks[i] = update_ref_lock(updates[i]->ref_name,
+                                          (updates[i]->have_old ?
+                                           updates[i]->old_sha1 : NULL),
+                                          updates[i]->flags,
+                                          &types[i], onerr);
+               if (!locks[i]) {
+                       ret = 1;
+                       goto cleanup;
+               }
+       }
+
+       /* Perform updates first so live commits remain referenced */
+       for (i = 0; i < n; i++)
+               if (!is_null_sha1(updates[i]->new_sha1)) {
+                       ret = update_ref_write(action,
+                                              updates[i]->ref_name,
+                                              updates[i]->new_sha1,
+                                              locks[i], onerr);
+                       locks[i] = NULL; /* freed by update_ref_write */
+                       if (ret)
+                               goto cleanup;
+               }
+
+       /* Perform deletes now that updates are safely completed */
+       for (i = 0; i < n; i++)
+               if (locks[i]) {
+                       delnames[delnum++] = locks[i]->ref_name;
+                       ret |= delete_ref_loose(locks[i], types[i]);
+               }
+       ret |= repack_without_refs(delnames, delnum);
+       for (i = 0; i < delnum; i++)
+               unlink_or_warn(git_path("logs/%s", delnames[i]));
+       clear_loose_ref_cache(&ref_cache);
+
+cleanup:
+       for (i = 0; i < n; i++)
+               if (locks[i])
+                       unlock_ref(locks[i]);
+       free(updates);
+       free(types);
+       free(locks);
+       free(delnames);
+       return ret;
 }
 
 char *shorten_unambiguous_ref(const char *refname, int strict)
@@ -3162,23 +3385,29 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
        static int nr_rules;
        char *short_name;
 
-       /* pre generate scanf formats from ref_rev_parse_rules[] */
        if (!nr_rules) {
+               /*
+                * Pre-generate scanf formats from ref_rev_parse_rules[].
+                * Generate a format suitable for scanf from a
+                * ref_rev_parse_rules rule by interpolating "%s" at the
+                * location of the "%.*s".
+                */
                size_t total_len = 0;
+               size_t offset = 0;
 
                /* the rule list is NULL terminated, count them first */
-               for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
-                       /* no +1 because strlen("%s") < strlen("%.*s") */
-                       total_len += strlen(ref_rev_parse_rules[nr_rules]);
+               for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
+                       /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
+                       total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
 
                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
 
-               total_len = 0;
+               offset = 0;
                for (i = 0; i < nr_rules; i++) {
-                       scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
-                                       + total_len;
-                       gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
-                       total_len += strlen(ref_rev_parse_rules[i]);
+                       assert(offset < total_len);
+                       scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
+                       offset += snprintf(scanf_fmts[i], total_len - offset,
+                                          ref_rev_parse_rules[i], 2, "%s") + 1;
                }
        }
 
@@ -3248,7 +3477,7 @@ int parse_hide_refs_config(const char *var, const char *value, const char *secti
 {
        if (!strcmp("transfer.hiderefs", var) ||
            /* NEEDSWORK: use parse_config_key() once both are merged */
-           (!prefixcmp(var, section) && var[strlen(section)] == '.' &&
+           (starts_with(var, section) && var[strlen(section)] == '.' &&
             !strcmp(var + strlen(section), ".hiderefs"))) {
                char *ref;
                int len;
@@ -3276,7 +3505,7 @@ int ref_is_hidden(const char *refname)
                return 0;
        for_each_string_list_item(item, hide_refs) {
                int len;
-               if (prefixcmp(refname, item->string))
+               if (!starts_with(refname, item->string))
                        continue;
                len = strlen(item->string);
                if (!refname[len] || refname[len] == '/')