Merge branch 'mh/get-remote-group-fix'
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index 7ac05cf21a25802f8e16d45ef75e37b7de2cda8a..2db2975e08b7cccd644eab6b4b0ad752e4ec02b3 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -19,12 +19,14 @@ struct ref_lock {
  * 1: End-of-component
  * 2: ., look for a preceding . to reject .. in refs
  * 3: {, look for a preceding @ to reject @{ in refs
- * 4: A bad character: ASCII control characters, "~", "^", ":" or SP
+ * 4: A bad character: ASCII control characters, and
+ *    ":", "?", "[", "\", "^", "~", SP, or TAB
+ * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  */
 static unsigned char refname_disposition[256] = {
        1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
        4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-       4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 1,
+       4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
@@ -62,6 +64,11 @@ static unsigned char refname_disposition[256] = {
  */
 #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
@@ -70,12 +77,14 @@ static unsigned char refname_disposition[256] = {
  *
  * - any path component of it begins with ".", or
  * - it has double dots "..", or
- * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
- * - it ends with a "/".
- * - it ends with ".lock"
- * - it contains a "\" (backslash)
+ * - it has ASCII control characters, or
+ * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
+ * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
+ * - it ends with a "/", or
+ * - it ends with ".lock", or
+ * - it contains a "@{" portion
  */
-static int check_refname_component(const char *refname, int flags)
+static int check_refname_component(const char *refname, int *flags)
 {
        const char *cp;
        char last = '\0';
@@ -96,6 +105,16 @@ static int check_refname_component(const char *refname, int flags)
                        break;
                case 4:
                        return -1;
+               case 5:
+                       if (!(*flags & REFNAME_REFSPEC_PATTERN))
+                               return -1; /* refspec can't be a pattern */
+
+                       /*
+                        * Unset the pattern flag so that we only accept
+                        * a single asterisk for one side of refspec.
+                        */
+                       *flags &= ~ REFNAME_REFSPEC_PATTERN;
+                       break;
                }
                last = ch;
        }
@@ -120,18 +139,10 @@ int check_refname_format(const char *refname, int flags)
 
        while (1) {
                /* We are at the start of a path component. */
-               component_len = check_refname_component(refname, flags);
-               if (component_len <= 0) {
-                       if ((flags & REFNAME_REFSPEC_PATTERN) &&
-                                       refname[0] == '*' &&
-                                       (refname[1] == '\0' || refname[1] == '/')) {
-                               /* Accept one wildcard as a full refname component. */
-                               flags &= ~REFNAME_REFSPEC_PATTERN;
-                               component_len = 1;
-                       } else {
-                               return -1;
-                       }
-               }
+               component_len = check_refname_component(refname, &flags);
+               if (component_len <= 0)
+                       return -1;
+
                component_count++;
                if (refname[component_len] == '\0')
                        break;
@@ -1314,7 +1325,13 @@ static struct ref_dir *get_packed_refs(struct ref_cache *refs)
        return get_packed_ref_dir(get_packed_ref_cache(refs));
 }
 
-void add_packed_ref(const char *refname, const unsigned char *sha1)
+/*
+ * 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);
@@ -1741,9 +1758,11 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
        return ret;
 }
 
-char *resolve_refdup(const char *ref, int resolve_flags, unsigned char *sha1, int *flags)
+char *resolve_refdup(const char *refname, int resolve_flags,
+                    unsigned char *sha1, int *flags)
 {
-       return xstrdup_or_null(resolve_ref_unsafe(ref, resolve_flags, sha1, flags));
+       return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
+                                                 sha1, flags));
 }
 
 /* The argument to filter_refs */
@@ -2122,7 +2141,8 @@ int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *c
 
 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, 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)
@@ -2530,8 +2550,12 @@ static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
        return 0;
 }
 
-/* This should return a meaningful errno on failure */
-int lock_packed_refs(int flags)
+/*
+ * 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;
@@ -2561,10 +2585,12 @@ int lock_packed_refs(int flags)
 }
 
 /*
- * Commit the packed refs changes.
- * On error we must make sure that errno contains a meaningful value.
+ * 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
  */
-int commit_packed_refs(void)
+static int commit_packed_refs(void)
 {
        struct packed_ref_cache *packed_ref_cache =
                get_packed_ref_cache(&ref_cache);
@@ -2593,7 +2619,12 @@ int commit_packed_refs(void)
        return error;
 }
 
-void rollback_packed_refs(void)
+/*
+ * 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);
@@ -2751,7 +2782,14 @@ int pack_refs(unsigned int flags)
        return 0;
 }
 
-int repack_without_refs(struct string_list *refnames, struct strbuf *err)
+/*
+ * 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;
@@ -2816,15 +2854,15 @@ static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
        return 0;
 }
 
-int delete_ref(const char *refname, const unsigned char *sha1, unsigned int flags)
+int delete_ref(const char *refname, const unsigned char *old_sha1,
+              unsigned int flags)
 {
        struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
 
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
-           ref_transaction_delete(transaction, refname,
-                                  (sha1 && !is_null_sha1(sha1)) ? sha1 : NULL,
+           ref_transaction_delete(transaction, refname, old_sha1,
                                   flags, NULL, &err) ||
            ref_transaction_commit(transaction, &err)) {
                error("%s", err.buf);
@@ -2837,6 +2875,44 @@ int delete_ref(const char *refname, const unsigned char *sha1, unsigned int flag
        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.
@@ -2910,9 +2986,11 @@ static int rename_ref_available(const char *oldname, const char *newname)
        return ret;
 }
 
-static int write_ref_to_lockfile(struct ref_lock *lock, const unsigned char *sha1);
+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);
+                            const unsigned char *sha1, const char *logmsg,
+                            int flags, struct strbuf *err);
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
@@ -2973,9 +3051,10 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        }
        hashcpy(lock->old_oid.hash, orig_sha1);
 
-       if (write_ref_to_lockfile(lock, orig_sha1) ||
-           commit_ref_update(lock, orig_sha1, logmsg)) {
-               error("unable to write current sha1 into %s", newrefname);
+       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;
        }
 
@@ -2991,9 +3070,11 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 
        flag = log_all_ref_updates;
        log_all_ref_updates = 0;
-       if (write_ref_to_lockfile(lock, orig_sha1) ||
-           commit_ref_update(lock, orig_sha1, NULL))
-               error("unable to write current sha1 into %s", oldrefname);
+       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:
@@ -3048,8 +3129,23 @@ static int copy_msg(char *buf, const char *msg)
        return cp - buf;
 }
 
-/* This function must set a meaningful errno on failure */
-int log_ref_setup(const char *refname, struct strbuf *sb_logfile)
+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 *sb_logfile, struct strbuf *err, int force_create)
 {
        int logfd, oflags = O_APPEND | O_WRONLY;
        char *logfile;
@@ -3058,15 +3154,10 @@ int log_ref_setup(const char *refname, struct strbuf *sb_logfile)
        logfile = sb_logfile->buf;
        /* make sure the rest of the function can't change "logfile" */
        sb_logfile = NULL;
-       if (log_all_ref_updates &&
-           (starts_with(refname, "refs/heads/") ||
-            starts_with(refname, "refs/remotes/") ||
-            starts_with(refname, "refs/notes/") ||
-            !strcmp(refname, "HEAD"))) {
+       if (force_create || should_autocreate_reflog(refname)) {
                if (safe_create_leading_directories(logfile) < 0) {
-                       int save_errno = errno;
-                       error("unable to create directory for %s", logfile);
-                       errno = save_errno;
+                       strbuf_addf(err, "unable to create directory for %s: "
+                                   "%s", logfile, strerror(errno));
                        return -1;
                }
                oflags |= O_CREAT;
@@ -3079,20 +3170,16 @@ int log_ref_setup(const char *refname, struct strbuf *sb_logfile)
 
                if (errno == EISDIR) {
                        if (remove_empty_directories(logfile)) {
-                               int save_errno = errno;
-                               error("There are still logs under '%s'",
-                                     logfile);
-                               errno = save_errno;
+                               strbuf_addf(err, "There are still logs under "
+                                           "'%s'", logfile);
                                return -1;
                        }
                        logfd = open(logfile, oflags, 0666);
                }
 
                if (logfd < 0) {
-                       int save_errno = errno;
-                       error("Unable to append to %s: %s", logfile,
-                             strerror(errno));
-                       errno = save_errno;
+                       strbuf_addf(err, "unable to append to %s: %s",
+                                   logfile, strerror(errno));
                        return -1;
                }
        }
@@ -3102,6 +3189,17 @@ int log_ref_setup(const char *refname, struct strbuf *sb_logfile)
        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)
@@ -3130,7 +3228,8 @@ static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
 
 static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
                           const unsigned char *new_sha1, const char *msg,
-                          struct strbuf *sb_log_file)
+                          struct strbuf *sb_log_file, int flags,
+                          struct strbuf *err)
 {
        int logfd, result, oflags = O_APPEND | O_WRONLY;
        char *log_file;
@@ -3138,7 +3237,8 @@ static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
        if (log_all_ref_updates < 0)
                log_all_ref_updates = !is_bare_repository();
 
-       result = log_ref_setup(refname, sb_log_file);
+       result = log_ref_setup(refname, sb_log_file, err, flags & REF_FORCE_CREATE_REFLOG);
+
        if (result)
                return result;
        log_file = sb_log_file->buf;
@@ -3151,26 +3251,26 @@ static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
        result = log_ref_write_fd(logfd, old_sha1, new_sha1,
                                  git_committer_info(0), msg);
        if (result) {
-               int save_errno = errno;
+               strbuf_addf(err, "unable to append to %s: %s", log_file,
+                           strerror(errno));
                close(logfd);
-               error("Unable to append to %s", log_file);
-               errno = save_errno;
                return -1;
        }
        if (close(logfd)) {
-               int save_errno = errno;
-               error("Unable to append to %s", log_file);
-               errno = save_errno;
+               strbuf_addf(err, "unable to append to %s: %s", log_file,
+                           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)
+                        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);
+       int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
+                                 err);
        strbuf_release(&sb);
        return ret;
 }
@@ -3182,36 +3282,36 @@ int is_branch(const char *refname)
 
 /*
  * Write sha1 into the open lockfile, then close the lockfile. On
- * errors, rollback the lockfile and set errno to reflect the problem.
+ * errors, rollback the lockfile, fill in *err and
+ * return -1.
  */
 static int write_ref_to_lockfile(struct ref_lock *lock,
-                                const unsigned char *sha1)
+                                const unsigned char *sha1, struct strbuf *err)
 {
        static char term = '\n';
        struct object *o;
 
        o = parse_object(sha1);
        if (!o) {
-               error("Trying to write ref %s with nonexistent object %s",
-                       lock->ref_name, sha1_to_hex(sha1));
+               strbuf_addf(err,
+                           "Trying to write ref %s with nonexistent object %s",
+                           lock->ref_name, sha1_to_hex(sha1));
                unlock_ref(lock);
-               errno = EINVAL;
                return -1;
        }
        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
-               error("Trying to write non-commit object %s to branch %s",
-                       sha1_to_hex(sha1), 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);
-               errno = EINVAL;
                return -1;
        }
        if (write_in_full(lock->lk->fd, sha1_to_hex(sha1), 40) != 40 ||
            write_in_full(lock->lk->fd, &term, 1) != 1 ||
            close_ref(lock) < 0) {
-               int save_errno = errno;
-               error("Couldn't write %s", lock->lk->filename.buf);
+               strbuf_addf(err,
+                           "Couldn't write %s", lock->lk->filename.buf);
                unlock_ref(lock);
-               errno = save_errno;
                return -1;
        }
        return 0;
@@ -3223,12 +3323,17 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
  * 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)
+                            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) < 0 ||
+       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) < 0)) {
+            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;
        }
@@ -3251,14 +3356,21 @@ static int commit_ref_update(struct ref_lock *lock,
                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))
-                       log_ref_write("HEAD", lock->old_oid.hash, sha1, logmsg);
+                   !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);
+                       }
+               }
        }
        if (commit_ref(lock)) {
                error("Couldn't set %s", lock->ref_name);
                unlock_ref(lock);
                return -1;
        }
+
        unlock_ref(lock);
        return 0;
 }
@@ -3271,6 +3383,7 @@ int create_symref(const char *ref_target, const char *refs_heads_master,
        int fd, len, written;
        char *git_HEAD = git_pathdup("%s", ref_target);
        unsigned char old_sha1[20], new_sha1[20];
+       struct strbuf err = STRBUF_INIT;
 
        if (logmsg && read_ref(ref_target, old_sha1))
                hashclr(old_sha1);
@@ -3319,8 +3432,11 @@ int create_symref(const char *ref_target, const char *refs_heads_master,
 #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);
+       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);
+       }
 
        free(git_HEAD);
        return 0;
@@ -3371,14 +3487,14 @@ static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
                        hashcpy(cb->sha1, nsha1);
                        if (hashcmp(cb->osha1, nsha1))
                                warning("Log for ref %s has gap after %s.",
-                                       cb->refname, show_date(cb->date, cb->tz, DATE_RFC2822));
+                                       cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
                }
                else if (cb->date == cb->at_time)
                        hashcpy(cb->sha1, nsha1);
                else if (hashcmp(nsha1, cb->sha1))
                        warning("Log for ref %s unexpectedly ended on %s.",
                                cb->refname, show_date(cb->date, cb->tz,
-                                                  DATE_RFC2822));
+                                                      DATE_MODE(RFC2822)));
                hashcpy(cb->osha1, osha1);
                hashcpy(cb->nsha1, nsha1);
                cb->found_it = 1;
@@ -3956,14 +4072,19 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                                 * value, so we don't need to write it.
                                 */
                        } else if (write_ref_to_lockfile(update->lock,
-                                                        update->new_sha1)) {
+                                                        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'.",
-                                           update->refname);
+                               strbuf_addf(err,
+                                           "cannot update the ref '%s': %s",
+                                           update->refname, write_err);
+                               free(write_err);
                                ret = TRANSACTION_GENERIC_ERROR;
                                goto cleanup;
                        } else {
@@ -3989,11 +4110,10 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 
                if (update->flags & REF_NEEDS_COMMIT) {
                        if (commit_ref_update(update->lock,
-                                             update->new_sha1, update->msg)) {
+                                             update->new_sha1, update->msg,
+                                             update->flags, err)) {
                                /* freed by commit_ref_update(): */
                                update->lock = NULL;
-                               strbuf_addf(err, "Cannot update the ref '%s'.",
-                                           update->refname);
                                ret = TRANSACTION_GENERIC_ERROR;
                                goto cleanup;
                        } else {
@@ -4038,6 +4158,98 @@ int ref_transaction_commit(struct ref_transaction *transaction,
        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)
+{
+       struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
+       struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
+       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,
+                                            loose_refs, err) ||
+                   verify_refname_available(update->refname,
+                                            &affected_refnames, NULL,
+                                            packed_refs, 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;