git-send-email: do not double-escape quotes from mutt
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index 47e4e5380a1e0fc04f8b81837c51c023f35871cf..305bb54169b41cfb53c2eff260cb6cd80f1810c4 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -57,6 +57,12 @@ static unsigned char refname_disposition[256] = {
  */
 #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
+
 /*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
@@ -263,7 +269,7 @@ struct ref_dir {
  * 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 is_refname_available().)
+ * 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
@@ -841,121 +847,181 @@ static void prime_ref_dir(struct ref_dir *dir)
        }
 }
 
-static int entry_matches(struct ref_entry *entry, const struct string_list *list)
-{
-       return list && string_list_has_string(list, entry->name);
-}
-
 struct nonmatching_ref_data {
        const struct string_list *skip;
-       struct ref_entry *found;
+       const char *conflicting_refname;
 };
 
 static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
 {
        struct nonmatching_ref_data *data = vdata;
 
-       if (entry_matches(entry, data->skip))
+       if (data->skip && string_list_has_string(data->skip, entry->name))
                return 0;
 
-       data->found = entry;
+       data->conflicting_refname = entry->name;
        return 1;
 }
 
-static void report_refname_conflict(struct ref_entry *entry,
-                                   const char *refname)
-{
-       error("'%s' exists; cannot create '%s'", entry->name, refname);
-}
-
 /*
- * Return true iff a reference named refname could be created without
- * conflicting with the name of an existing reference in dir.  If
- * skip is non-NULL, ignore potential conflicts with refs in skip
- * (e.g., because they are scheduled for deletion in the same
- * operation).
+ * Return 0 if a reference named refname could be created without
+ * conflicting with the name of an existing reference in dir.
+ * 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".
+ * leading components of the other; e.g., "refs/foo/bar" conflicts
+ * with both "refs/foo" and with "refs/foo/bar/baz" but not with
+ * "refs/foo/bar" or "refs/foo/barbados".
  *
- * skip must be sorted.
+ * extras and skip must be sorted.
  */
-static int is_refname_available(const char *refname,
-                               const struct string_list *skip,
-                               struct ref_dir *dir)
+static int verify_refname_available(const char *refname,
+                                   const struct string_list *extras,
+                                   const struct string_list *skip,
+                                   struct ref_dir *dir,
+                                   struct strbuf *err)
 {
        const char *slash;
-       size_t len;
        int pos;
-       char *dirname;
+       struct strbuf dirname = STRBUF_INIT;
+       int ret = -1;
+
+       /*
+        * For the sake of comments in this function, suppose that
+        * refname is "refs/foo/bar".
+        */
+
+       assert(err);
 
+       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);
+
                /*
-                * We are still at a leading dir of the refname; we are
-                * looking for a conflict with a leaf entry.
-                *
-                * If we find one, we still must make sure it is
-                * not in "skip".
+                * 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.
                 */
-               pos = search_ref_dir(dir, refname, slash - refname);
-               if (pos >= 0) {
-                       struct ref_entry *entry = dir->entries[pos];
-                       if (entry_matches(entry, skip))
-                               return 1;
-                       report_refname_conflict(entry, refname);
-                       return 0;
+               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;
+                       }
                }
 
+               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;
+               }
 
                /*
                 * Otherwise, we can try to continue our search with
-                * the next component; if we come up empty, we know
-                * there is nothing under this whole prefix.
+                * 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.
                 */
-               pos = search_ref_dir(dir, refname, slash + 1 - refname);
-               if (pos < 0)
-                       return 1;
-
-               dir = get_ref_dir(dir->entries[pos]);
+               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]);
+                       }
+               }
        }
 
        /*
-        * We are at the leaf of our refname; we want to
-        * make sure there are no directories which match it.
+        * 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.
         */
-       len = strlen(refname);
-       dirname = xmallocz(len + 1);
-       sprintf(dirname, "%s/", refname);
-       pos = search_ref_dir(dir, dirname, len + 1);
-       free(dirname);
+       strbuf_addstr(&dirname, refname + dirname.len);
+       strbuf_addch(&dirname, '/');
 
-       if (pos >= 0) {
+       if (dir) {
+               pos = search_ref_dir(dir, dirname.buf, dirname.len);
+
+               if (pos >= 0) {
+                       /*
+                        * We found a directory named "$refname/"
+                        * (e.g., "refs/foo/bar/"). It is a problem
+                        * iff it contains any ref that is not in
+                        * "skip".
+                        */
+                       struct nonmatching_ref_data data;
+
+                       data.skip = skip;
+                       data.conflicting_refname = NULL;
+                       dir = get_ref_dir(dir->entries[pos]);
+                       sort_ref_dir(dir);
+                       if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
+                               strbuf_addf(err, "'%s' exists; cannot create '%s'",
+                                           data.conflicting_refname, refname);
+                               goto cleanup;
+                       }
+               }
+       }
+
+       if (extras) {
                /*
-                * We found a directory named "refname". It is a
-                * problem iff it contains any ref that is not
-                * in "skip".
+                * Check for entries in extras that start with
+                * "$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.
                 */
-               struct ref_entry *entry = dir->entries[pos];
-               struct ref_dir *dir = get_ref_dir(entry);
-               struct nonmatching_ref_data data;
+               for (pos = string_list_find_insert_index(extras, dirname.buf, 0);
+                    pos < extras->nr; pos++) {
+                       const char *extra_refname = extras->items[pos].string;
 
-               data.skip = skip;
-               sort_ref_dir(dir);
-               if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data))
-                       return 1;
+                       if (!starts_with(extra_refname, dirname.buf))
+                               break;
 
-               report_refname_conflict(data.found, refname);
-               return 0;
+                       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;
+                       }
+               }
        }
 
-       /*
-        * There is no point in searching for another leaf
-        * node which matches it; such an entry would be the
-        * ref we are looking for, not a conflict.
-        */
-       return 1;
+       /* No conflicts were found */
+       ret = 0;
+
+cleanup:
+       strbuf_release(&dirname);
+       return ret;
 }
 
 struct packed_ref_cache {
@@ -1308,19 +1374,34 @@ static void read_loose_refs(const char *dirname, struct ref_dir *dir)
                                         create_dir_entry(refs, refname.buf,
                                                          refname.len, 1));
                } else {
+                       int read_ok;
+
                        if (*refs->name) {
                                hashclr(sha1);
                                flag = 0;
-                               if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
-                                       hashclr(sha1);
-                                       flag |= REF_ISBROKEN;
-                               }
-                       } else if (read_ref_full(refname.buf,
-                                                RESOLVE_REF_READING,
-                                                sha1, &flag)) {
+                               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)) {
                                hashclr(sha1);
@@ -2271,8 +2352,10 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
  */
 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)
+                                           unsigned int flags, int *type_p,
+                                           struct strbuf *err)
 {
        char *ref_file;
        const char *orig_refname = refname;
@@ -2283,6 +2366,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        int resolve_flags = 0;
        int attempts_remaining = 3;
 
+       assert(err);
+
        lock = xcalloc(1, sizeof(struct ref_lock));
        lock->lock_fd = -1;
 
@@ -2305,7 +2390,12 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                ref_file = git_path("%s", orig_refname);
                if (remove_empty_directories(ref_file)) {
                        last_errno = errno;
-                       error("there are still refs under '%s'", orig_refname);
+
+                       if (!verify_refname_available(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,
@@ -2315,8 +2405,12 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
            *type_p = type;
        if (!refname) {
                last_errno = errno;
-               error("unable to resolve reference %s: %s",
-                       orig_refname, strerror(errno));
+               if (last_errno != ENOTDIR ||
+                   !verify_refname_available(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;
        }
        /*
@@ -2326,7 +2420,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
         * our refname.
         */
        if (is_null_sha1(lock->old_sha1) &&
-            !is_refname_available(refname, skip, get_packed_refs(&ref_cache))) {
+           verify_refname_available(refname, extras, skip,
+                                    get_packed_refs(&ref_cache), err)) {
                last_errno = ENOTDIR;
                goto error_return;
        }
@@ -2352,7 +2447,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                /* fall through */
        default:
                last_errno = errno;
-               error("unable to create directory for %s", ref_file);
+               strbuf_addf(err, "unable to create directory for %s", ref_file);
                goto error_return;
        }
 
@@ -2367,10 +2462,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                         */
                        goto retry;
                else {
-                       struct strbuf err = STRBUF_INIT;
-                       unable_to_lock_message(ref_file, errno, &err);
-                       error("%s", err.buf);
-                       strbuf_release(&err);
+                       unable_to_lock_message(ref_file, errno, err);
                        goto error_return;
                }
        }
@@ -2764,17 +2856,25 @@ static int rename_tmp_log(const char *newrefname)
 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 = is_refname_available(newname, &skip, get_packed_refs(&ref_cache))
-           && is_refname_available(newname, &skip, get_loose_refs(&ref_cache));
+       ret = !verify_refname_available(newname, NULL, &skip,
+                                       get_packed_refs(&ref_cache), &err)
+               && !verify_refname_available(newname, NULL, &skip,
+                                            get_loose_refs(&ref_cache), &err);
+       if (!ret)
+               error("%s", err.buf);
+
        string_list_clear(&skip, 0);
+       strbuf_release(&err);
        return ret;
 }
 
-static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
-                         const char *logmsg);
+static int write_ref_to_lockfile(struct ref_lock *lock, const unsigned char *sha1);
+static int commit_ref_update(struct ref_lock *lock,
+                            const unsigned char *sha1, const char *logmsg);
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
@@ -2784,6 +2884,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        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);
@@ -2826,13 +2927,16 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 
        logmoved = log;
 
-       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, 0, NULL);
+       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, 0, NULL, &err);
        if (!lock) {
-               error("unable to lock %s for update", newrefname);
+               error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+               strbuf_release(&err);
                goto rollback;
        }
        hashcpy(lock->old_sha1, orig_sha1);
-       if (write_ref_sha1(lock, orig_sha1, logmsg)) {
+
+       if (write_ref_to_lockfile(lock, orig_sha1) ||
+           commit_ref_update(lock, orig_sha1, logmsg)) {
                error("unable to write current sha1 into %s", newrefname);
                goto rollback;
        }
@@ -2840,15 +2944,17 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        return 0;
 
  rollback:
-       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, 0, NULL);
+       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, 0, NULL, &err);
        if (!lock) {
-               error("unable to lock %s for rollback", oldrefname);
+               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_sha1(lock, orig_sha1, NULL))
+       if (write_ref_to_lockfile(lock, orig_sha1) ||
+           commit_ref_update(lock, orig_sha1, NULL))
                error("unable to write current sha1 into %s", oldrefname);
        log_all_ref_updates = flag;
 
@@ -3022,11 +3128,11 @@ int is_branch(const char *refname)
 }
 
 /*
- * Write sha1 into the ref specified by the lock. Make sure that errno
- * is sane on error.
+ * Write sha1 into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile and set errno to reflect the problem.
  */
-static int write_ref_sha1(struct ref_lock *lock,
-       const unsigned char *sha1, const char *logmsg)
+static int write_ref_to_lockfile(struct ref_lock *lock,
+                                const unsigned char *sha1)
 {
        static char term = '\n';
        struct object *o;
@@ -3055,6 +3161,17 @@ static int write_ref_sha1(struct ref_lock *lock,
                errno = save_errno;
                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)
+{
        clear_loose_ref_cache(&ref_cache);
        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
            (strcmp(lock->ref_name, lock->orig_ref_name) &&
@@ -3695,25 +3812,18 @@ int update_ref(const char *msg, const char *refname,
        return 0;
 }
 
-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)->refname, (*u2)->refname);
-}
-
-static int ref_update_reject_duplicates(struct ref_update **updates, int n,
+static int ref_update_reject_duplicates(struct string_list *refnames,
                                        struct strbuf *err)
 {
-       int i;
+       int i, n = refnames->nr;
 
        assert(err);
 
        for (i = 1; i < n; i++)
-               if (!strcmp(updates[i - 1]->refname, updates[i]->refname)) {
+               if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
                        strbuf_addf(err,
                                    "Multiple updates for ref '%s' not allowed.",
-                                   updates[i]->refname);
+                                   refnames->items[i].string);
                        return 1;
                }
        return 0;
@@ -3727,6 +3837,7 @@ int ref_transaction_commit(struct ref_transaction *transaction,
        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);
 
@@ -3738,63 +3849,101 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                return 0;
        }
 
-       /* Copy, sort, and reject duplicate refs */
-       qsort(updates, n, sizeof(*updates), ref_update_compare);
-       if (ref_update_reject_duplicates(updates, n, err)) {
+       /* 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 while verifying old values */
+       /*
+        * 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];
-               unsigned int flags = update->flags;
 
-               if ((flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
-                       flags |= REF_DELETING;
+               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),
-                               NULL,
-                               flags,
-                               &update->type);
+                               &affected_refnames, NULL,
+                               update->flags,
+                               &update->type,
+                               err);
                if (!update->lock) {
+                       char *reason;
+
                        ret = (errno == ENOTDIR)
                                ? TRANSACTION_NAME_CONFLICT
                                : TRANSACTION_GENERIC_ERROR;
-                       strbuf_addf(err, "Cannot lock the ref '%s'.",
-                                   update->refname);
+                       reason = strbuf_detach(err, NULL);
+                       strbuf_addf(err, "Cannot lock ref '%s': %s",
+                                   update->refname, reason);
+                       free(reason);
                        goto cleanup;
                }
-       }
-
-       /* Perform updates first so live commits remain referenced */
-       for (i = 0; i < n; i++) {
-               struct ref_update *update = updates[i];
-               int flags = update->flags;
-
-               if ((flags & REF_HAVE_NEW) && !is_null_sha1(update->new_sha1)) {
+               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_sha1, update->new_sha1)) {
+                       if (!overwriting_symref &&
+                           !hashcmp(update->lock->old_sha1, update->new_sha1)) {
                                /*
                                 * The reference already has the desired
                                 * value, so we don't need to write it.
                                 */
-                               unlock_ref(update->lock);
+                       } else if (write_ref_to_lockfile(update->lock,
+                                                        update->new_sha1)) {
+                               /*
+                                * The lock was freed upon failure of
+                                * write_ref_to_lockfile():
+                                */
                                update->lock = NULL;
-                       } else if (write_ref_sha1(update->lock, update->new_sha1,
-                                                 update->msg)) {
-                               update->lock = NULL; /* freed by write_ref_sha1 */
                                strbuf_addf(err, "Cannot update the ref '%s'.",
                                            update->refname);
                                ret = TRANSACTION_GENERIC_ERROR;
                                goto cleanup;
                        } else {
-                               /* freed by write_ref_sha1(): */
+                               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)) {
+                               /* 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 {
+                               /* freed by commit_ref_update(): */
                                update->lock = NULL;
                        }
                }
@@ -3803,15 +3952,14 @@ int ref_transaction_commit(struct ref_transaction *transaction,
        /* Perform deletes now that updates are safely completed */
        for (i = 0; i < n; i++) {
                struct ref_update *update = updates[i];
-               int flags = update->flags;
 
-               if ((flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1)) {
+               if (update->flags & REF_DELETING) {
                        if (delete_ref_loose(update->lock, update->type, err)) {
                                ret = TRANSACTION_GENERIC_ERROR;
                                goto cleanup;
                        }
 
-                       if (!(flags & REF_ISPRUNING))
+                       if (!(update->flags & REF_ISPRUNING))
                                string_list_append(&refs_to_delete,
                                                   update->lock->ref_name);
                }
@@ -3832,6 +3980,7 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                if (updates[i]->lock)
                        unlock_ref(updates[i]->lock);
        string_list_clear(&refs_to_delete, 0);
+       string_list_clear(&affected_refnames, 0);
        return ret;
 }
 
@@ -4021,6 +4170,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
        char *log_file;
        int status = 0;
        int type;
+       struct strbuf err = STRBUF_INIT;
 
        memset(&cb, 0, sizeof(cb));
        cb.flags = flags;
@@ -4032,9 +4182,12 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
         * reference itself, plus we might need to update the
         * reference if --updateref was specified:
         */
-       lock = lock_ref_sha1_basic(refname, sha1, NULL, 0, &type);
-       if (!lock)
-               return error("cannot lock ref '%s'", refname);
+       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;