1 files changed, 253 insertions, 234 deletions

diff --git a/refs/files-backend.c b/refs/files-backend.c
index c041d4ba21..50188e92f9 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -912,6 +912,14 @@ struct packed_ref_cache {
  */
 struct files_ref_store {
 	struct ref_store base;
+
+	/*
+	 * The name of the submodule represented by this object, or
+	 * NULL if it represents the main repository's reference
+	 * store:
+	 */
+	const char *submodule;
+
 	struct ref_entry *loose;
 	struct packed_ref_cache *packed;
 };
@@ -972,12 +980,25 @@ static struct ref_store *files_ref_store_create(const char *submodule)
 	struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
 	struct ref_store *ref_store = (struct ref_store *)refs;
 
-	base_ref_store_init(ref_store, &refs_be_files, submodule);
+	base_ref_store_init(ref_store, &refs_be_files);
+
+	refs->submodule = xstrdup_or_null(submodule);
 
 	return ref_store;
 }
 
 /*
+ * Die if refs is for a submodule (i.e., not for the main repository).
+ * caller is used in any necessary error messages.
+ */
+static void files_assert_main_repository(struct files_ref_store *refs,
+					 const char *caller)
+{
+	if (refs->submodule)
+		die("BUG: %s called for a submodule", caller);
+}
+
+/*
  * Downcast ref_store to files_ref_store. Die if ref_store is not a
  * files_ref_store. If submodule_allowed is not true, then also die if
  * files_ref_store is for a submodule (i.e., not for the main
@@ -987,14 +1008,18 @@ static struct files_ref_store *files_downcast(
 		struct ref_store *ref_store, int submodule_allowed,
 		const char *caller)
 {
+	struct files_ref_store *refs;
+
 	if (ref_store->be != &refs_be_files)
 		die("BUG: ref_store is type \"%s\" not \"files\" in %s",
 		    ref_store->be->name, caller);
 
+	refs = (struct files_ref_store *)ref_store;
+
 	if (!submodule_allowed)
-		assert_main_repository(ref_store, caller);
+		files_assert_main_repository(refs, caller);
 
-	return (struct files_ref_store *)ref_store;
+	return refs;
 }
 
 /* The length of a peeled reference line in packed-refs, including EOL: */
@@ -1133,8 +1158,8 @@ static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *ref
 {
 	char *packed_refs_file;
 
-	if (*refs->base.submodule)
-		packed_refs_file = git_pathdup_submodule(refs->base.submodule,
+	if (refs->submodule)
+		packed_refs_file = git_pathdup_submodule(refs->submodule,
 							 "packed-refs");
 	else
 		packed_refs_file = git_pathdup("packed-refs");
@@ -1203,8 +1228,8 @@ static void read_loose_refs(const char *dirname, struct ref_dir *dir)
 	size_t path_baselen;
 	int err = 0;
 
-	if (*refs->base.submodule)
-		err = strbuf_git_path_submodule(&path, refs->base.submodule, "%s", dirname);
+	if (refs->submodule)
+		err = strbuf_git_path_submodule(&path, refs->submodule, "%s", dirname);
 	else
 		strbuf_git_path(&path, "%s", dirname);
 	path_baselen = path.len;
@@ -1242,20 +1267,10 @@ 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->base.submodule) {
-				hashclr(sha1);
-				flag = 0;
-				read_ok = !resolve_gitlink_ref(refs->base.submodule,
-							       refname.buf, sha1);
-			} else {
-				read_ok = !read_ref_full(refname.buf,
-							 RESOLVE_REF_READING,
-							 sha1, &flag);
-			}
-
-			if (!read_ok) {
+			if (!resolve_ref_recursively(&refs->base,
+						     refname.buf,
+						     RESOLVE_REF_READING,
+						     sha1, &flag)) {
 				hashclr(sha1);
 				flag |= REF_ISBROKEN;
 			} else if (is_null_sha1(sha1)) {
@@ -1358,8 +1373,8 @@ static int files_read_raw_ref(struct ref_store *ref_store,
 	*type = 0;
 	strbuf_reset(&sb_path);
 
-	if (*refs->base.submodule)
-		strbuf_git_path_submodule(&sb_path, refs->base.submodule, "%s", refname);
+	if (refs->submodule)
+		strbuf_git_path_submodule(&sb_path, refs->submodule, "%s", refname);
 	else
 		strbuf_git_path(&sb_path, "%s", refname);
 
@@ -1540,7 +1555,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
 	int ret = TRANSACTION_GENERIC_ERROR;
 
 	assert(err);
-	assert_main_repository(&refs->base, "lock_raw_ref");
+	files_assert_main_repository(refs, "lock_raw_ref");
 
 	*type = 0;
 
@@ -1985,6 +2000,13 @@ static int remove_empty_directories(struct strbuf *path)
 	return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
 }
 
+static int create_reflock(const char *path, void *cb)
+{
+	struct lock_file *lk = cb;
+
+	return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0;
+}
+
 /*
  * Locks a ref returning the lock on success and NULL on failure.
  * On failure errno is set to something meaningful.
@@ -2000,13 +2022,11 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 	struct strbuf ref_file = STRBUF_INIT;
 	struct ref_lock *lock;
 	int last_errno = 0;
-	int lflags = LOCK_NO_DEREF;
 	int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 	int resolve_flags = RESOLVE_REF_NO_RECURSE;
-	int attempts_remaining = 3;
 	int resolved;
 
-	assert_main_repository(&refs->base, "lock_ref_sha1_basic");
+	files_assert_main_repository(refs, "lock_ref_sha1_basic");
 	assert(err);
 
 	lock = xcalloc(1, sizeof(struct ref_lock));
@@ -2068,35 +2088,12 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 
 	lock->ref_name = xstrdup(refname);
 
- retry:
-	switch (safe_create_leading_directories_const(ref_file.buf)) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
+	if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
 		last_errno = errno;
-		strbuf_addf(err, "unable to create directory for '%s'",
-			    ref_file.buf);
+		unable_to_lock_message(ref_file.buf, errno, err);
 		goto error_return;
 	}
 
-	if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
-		last_errno = errno;
-		if (errno == ENOENT && --attempts_remaining > 0)
-			/*
-			 * Maybe somebody just deleted one of the
-			 * directories leading to ref_file.  Try
-			 * again:
-			 */
-			goto retry;
-		else {
-			unable_to_lock_message(ref_file.buf, errno, err);
-			goto error_return;
-		}
-	}
 	if (verify_lock(lock, old_sha1, mustexist, err)) {
 		last_errno = errno;
 		goto error_return;
@@ -2152,7 +2149,7 @@ static int lock_packed_refs(struct files_ref_store *refs, int flags)
 	static int timeout_value = 1000;
 	struct packed_ref_cache *packed_ref_cache;
 
-	assert_main_repository(&refs->base, "lock_packed_refs");
+	files_assert_main_repository(refs, "lock_packed_refs");
 
 	if (!timeout_configured) {
 		git_config_get_int("core.packedrefstimeout", &timeout_value);
@@ -2190,7 +2187,7 @@ static int commit_packed_refs(struct files_ref_store *refs)
 	int save_errno = 0;
 	FILE *out;
 
-	assert_main_repository(&refs->base, "commit_packed_refs");
+	files_assert_main_repository(refs, "commit_packed_refs");
 
 	if (!packed_ref_cache->lock)
 		die("internal error: packed-refs not locked");
@@ -2223,7 +2220,7 @@ static void rollback_packed_refs(struct files_ref_store *refs)
 	struct packed_ref_cache *packed_ref_cache =
 		get_packed_ref_cache(refs);
 
-	assert_main_repository(&refs->base, "rollback_packed_refs");
+	files_assert_main_repository(refs, "rollback_packed_refs");
 
 	if (!packed_ref_cache->lock)
 		die("internal error: packed-refs not locked");
@@ -2298,15 +2295,25 @@ static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
 	return 0;
 }
 
+enum {
+	REMOVE_EMPTY_PARENTS_REF = 0x01,
+	REMOVE_EMPTY_PARENTS_REFLOG = 0x02
+};
+
 /*
- * Remove empty parents, but spare refs/ and immediate subdirs.
- * Note: munges *name.
+ * Remove empty parent directories associated with the specified
+ * reference and/or its reflog, but spare [logs/]refs/ and immediate
+ * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
+ * REMOVE_EMPTY_PARENTS_REFLOG.
  */
-static void try_remove_empty_parents(char *name)
+static void try_remove_empty_parents(const char *refname, unsigned int flags)
 {
+	struct strbuf buf = STRBUF_INIT;
 	char *p, *q;
 	int i;
-	p = name;
+
+	strbuf_addstr(&buf, refname);
+	p = buf.buf;
 	for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
 		while (*p && *p != '/')
 			p++;
@@ -2314,19 +2321,23 @@ static void try_remove_empty_parents(char *name)
 		while (*p == '/')
 			p++;
 	}
-	for (q = p; *q; q++)
-		;
-	while (1) {
+	q = buf.buf + buf.len;
+	while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
 		while (q > p && *q != '/')
 			q--;
 		while (q > p && *(q-1) == '/')
 			q--;
 		if (q == p)
 			break;
-		*q = '\0';
-		if (rmdir(git_path("%s", name)))
-			break;
+		strbuf_setlen(&buf, q - buf.buf);
+		if ((flags & REMOVE_EMPTY_PARENTS_REF) &&
+		    rmdir(git_path("%s", buf.buf)))
+			flags &= ~REMOVE_EMPTY_PARENTS_REF;
+		if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) &&
+		    rmdir(git_path("logs/%s", buf.buf)))
+			flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
 	}
+	strbuf_release(&buf);
 }
 
 /* make sure nobody touched the ref, and unlink */
@@ -2350,7 +2361,6 @@ static void prune_ref(struct ref_to_prune *r)
 	}
 	ref_transaction_free(transaction);
 	strbuf_release(&err);
-	try_remove_empty_parents(r->name);
 }
 
 static void prune_refs(struct ref_to_prune *r)
@@ -2397,7 +2407,7 @@ static int repack_without_refs(struct files_ref_store *refs,
 	struct string_list_item *refname;
 	int ret, needs_repacking = 0, removed = 0;
 
-	assert_main_repository(&refs->base, "repack_without_refs");
+	files_assert_main_repository(refs, "repack_without_refs");
 	assert(err);
 
 	/* Look for a packed ref */
@@ -2439,24 +2449,6 @@ static int repack_without_refs(struct files_ref_store *refs,
 	return ret;
 }
 
-static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
-{
-	assert(err);
-
-	if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
-		/*
-		 * loose.  The loose file name is the same as the
-		 * lockfile name, minus ".lock":
-		 */
-		char *loose_filename = get_locked_file_path(lock->lk);
-		int res = unlink_or_msg(loose_filename, err);
-		free(loose_filename);
-		if (res)
-			return 1;
-	}
-	return 0;
-}
-
 static int files_delete_refs(struct ref_store *ref_store,
 			     struct string_list *refnames, unsigned int flags)
 {
@@ -2489,7 +2481,7 @@ static int files_delete_refs(struct ref_store *ref_store,
 	for (i = 0; i < refnames->nr; i++) {
 		const char *refname = refnames->items[i].string;
 
-		if (delete_ref(refname, NULL, flags))
+		if (delete_ref(NULL, refname, NULL, flags))
 			result |= error(_("could not remove reference %s"), refname);
 	}
 
@@ -2507,55 +2499,43 @@ out:
  */
 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
 
-static int rename_tmp_log(const char *newrefname)
+static int rename_tmp_log_callback(const char *path, void *cb)
 {
-	int attempts_remaining = 4;
-	struct strbuf path = STRBUF_INIT;
-	int ret = -1;
+	int *true_errno = cb;
 
- retry:
-	strbuf_reset(&path);
-	strbuf_git_path(&path, "logs/%s", newrefname);
-	switch (safe_create_leading_directories_const(path.buf)) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		error("unable to create directory for %s", newrefname);
-		goto out;
+	if (rename(git_path(TMP_RENAMED_LOG), path)) {
+		/*
+		 * rename(a, b) when b is an existing directory ought
+		 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
+		 * Sheesh. Record the true errno for error reporting,
+		 * but report EISDIR to raceproof_create_file() so
+		 * that it knows to retry.
+		 */
+		*true_errno = errno;
+		if (errno == ENOTDIR)
+			errno = EISDIR;
+		return -1;
+	} else {
+		return 0;
 	}
+}
 
-	if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
-		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
-			/*
-			 * rename(a, b) when b is an existing
-			 * directory ought to result in ISDIR, but
-			 * Solaris 5.8 gives ENOTDIR.  Sheesh.
-			 */
-			if (remove_empty_directories(&path)) {
-				error("Directory not empty: logs/%s", newrefname);
-				goto out;
-			}
-			goto retry;
-		} else if (errno == ENOENT && --attempts_remaining > 0) {
-			/*
-			 * Maybe another process just deleted one of
-			 * the directories in the path to newrefname.
-			 * Try again from the beginning.
-			 */
-			goto retry;
-		} else {
-			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-				newrefname, strerror(errno));
-			goto out;
-		}
+static int rename_tmp_log(const char *newrefname)
+{
+	char *path = git_pathdup("logs/%s", newrefname);
+	int ret, true_errno;
+
+	ret = raceproof_create_file(path, rename_tmp_log_callback, &true_errno);
+	if (ret) {
+		if (errno == EISDIR)
+			error("directory not empty: %s", path);
+		else
+			error("unable to move logfile %s to %s: %s",
+			      git_path(TMP_RENAMED_LOG), path,
+			      strerror(true_errno));
 	}
-	ret = 0;
-out:
-	strbuf_release(&path);
+
+	free(path);
 	return ret;
 }
 
@@ -2616,7 +2596,7 @@ static int files_rename_ref(struct ref_store *ref_store,
 		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
 			oldrefname, strerror(errno));
 
-	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
+	if (delete_ref(logmsg, oldrefname, orig_sha1, REF_NODEREF)) {
 		error("unable to delete old %s", oldrefname);
 		goto rollback;
 	}
@@ -2630,8 +2610,8 @@ static int files_rename_ref(struct ref_store *ref_store,
 	 */
 	if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
 			   sha1, NULL) &&
-	    delete_ref(newrefname, NULL, REF_NODEREF)) {
-		if (errno==EISDIR) {
+	    delete_ref(NULL, newrefname, NULL, REF_NODEREF)) {
+		if (errno == EISDIR) {
 			struct strbuf path = STRBUF_INIT;
 			int result;
 
@@ -2740,66 +2720,89 @@ static int commit_ref(struct ref_lock *lock)
 	return 0;
 }
 
+static int open_or_create_logfile(const char *path, void *cb)
+{
+	int *fd = cb;
+
+	*fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
+	return (*fd < 0) ? -1 : 0;
+}
+
 /*
- * 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.
+ * Create a reflog for a ref. If force_create = 0, only create the
+ * reflog for certain refs (those for which should_autocreate_reflog
+ * returns non-zero). Otherwise, create it regardless of the reference
+ * name. If the logfile already existed or was created, return 0 and
+ * set *logfd to the file descriptor opened for appending to the file.
+ * If no logfile exists and we decided not to create one, return 0 and
+ * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
+ * return -1.
  */
-static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
+static int log_ref_setup(const char *refname, int force_create,
+			 int *logfd, struct strbuf *err)
 {
-	int logfd, oflags = O_APPEND | O_WRONLY;
+	char *logfile = git_pathdup("logs/%s", refname);
 
-	strbuf_git_path(logfile, "logs/%s", refname);
 	if (force_create || should_autocreate_reflog(refname)) {
-		if (safe_create_leading_directories(logfile->buf) < 0) {
-			strbuf_addf(err, "unable to create directory for '%s': "
-				    "%s", logfile->buf, strerror(errno));
-			return -1;
-		}
-		oflags |= O_CREAT;
-	}
-
-	logfd = open(logfile->buf, oflags, 0666);
-	if (logfd < 0) {
-		if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
-			return 0;
+		if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
+			if (errno == ENOENT)
+				strbuf_addf(err, "unable to create directory for '%s': "
+					    "%s", logfile, strerror(errno));
+			else if (errno == EISDIR)
+				strbuf_addf(err, "there are still logs under '%s'",
+					    logfile);
+			else
+				strbuf_addf(err, "unable to append to '%s': %s",
+					    logfile, strerror(errno));
 
-		if (errno == EISDIR) {
-			if (remove_empty_directories(logfile)) {
-				strbuf_addf(err, "there are still logs under "
-					    "'%s'", logfile->buf);
-				return -1;
-			}
-			logfd = open(logfile->buf, oflags, 0666);
+			goto error;
 		}
-
-		if (logfd < 0) {
-			strbuf_addf(err, "unable to append to '%s': %s",
-				    logfile->buf, strerror(errno));
-			return -1;
+	} else {
+		*logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
+		if (*logfd < 0) {
+			if (errno == ENOENT || errno == EISDIR) {
+				/*
+				 * The logfile doesn't already exist,
+				 * but that is not an error; it only
+				 * means that we won't write log
+				 * entries to it.
+				 */
+				;
+			} else {
+				strbuf_addf(err, "unable to append to '%s': %s",
+					    logfile, strerror(errno));
+				goto error;
+			}
 		}
 	}
 
-	adjust_shared_perm(logfile->buf);
-	close(logfd);
+	if (*logfd >= 0)
+		adjust_shared_perm(logfile);
+
+	free(logfile);
 	return 0;
-}
 
+error:
+	free(logfile);
+	return -1;
+}
 
 static int files_create_reflog(struct ref_store *ref_store,
 			       const char *refname, int force_create,
 			       struct strbuf *err)
 {
-	int ret;
-	struct strbuf sb = STRBUF_INIT;
+	int fd;
 
 	/* Check validity (but we don't need the result): */
 	files_downcast(ref_store, 0, "create_reflog");
 
-	ret = log_ref_setup(refname, &sb, err, force_create);
-	strbuf_release(&sb);
-	return ret;
+	if (log_ref_setup(refname, force_create, &fd, err))
+		return -1;
+
+	if (fd >= 0)
+		close(fd);
+
+	return 0;
 }
 
 static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
@@ -2828,59 +2831,43 @@ static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
 	return 0;
 }
 
-static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
-			   const unsigned char *new_sha1, const char *msg,
-			   struct strbuf *logfile, int flags,
-			   struct strbuf *err)
+int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
+			const unsigned char *new_sha1, const char *msg,
+			int flags, struct strbuf *err)
 {
-	int logfd, result, oflags = O_APPEND | O_WRONLY;
+	int logfd, result;
 
 	if (log_all_ref_updates == LOG_REFS_UNSET)
 		log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
 
-	result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
+	result = log_ref_setup(refname, flags & REF_FORCE_CREATE_REFLOG,
+			       &logfd, err);
 
 	if (result)
 		return result;
 
-	logfd = open(logfile->buf, oflags);
 	if (logfd < 0)
 		return 0;
 	result = log_ref_write_fd(logfd, old_sha1, new_sha1,
 				  git_committer_info(0), msg);
 	if (result) {
-		strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
-			    strerror(errno));
+		int save_errno = errno;
+
+		strbuf_addf(err, "unable to append to '%s': %s",
+			    git_path("logs/%s", refname), strerror(save_errno));
 		close(logfd);
 		return -1;
 	}
 	if (close(logfd)) {
-		strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
-			    strerror(errno));
+		int save_errno = errno;
+
+		strbuf_addf(err, "unable to append to '%s': %s",
+			    git_path("logs/%s", refname), strerror(save_errno));
 		return -1;
 	}
 	return 0;
 }
 
-static int log_ref_write(const char *refname, const unsigned char *old_sha1,
-			 const unsigned char *new_sha1, const char *msg,
-			 int flags, struct strbuf *err)
-{
-	return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
-				   err);
-}
-
-int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
-			const unsigned char *new_sha1, const char *msg,
-			int flags, struct strbuf *err)
-{
-	struct strbuf sb = STRBUF_INIT;
-	int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
-				  err);
-	strbuf_release(&sb);
-	return ret;
-}
-
 /*
  * Write sha1 into the open lockfile, then close the lockfile. On
  * errors, rollback the lockfile, fill in *err and
@@ -2930,10 +2917,11 @@ static int commit_ref_update(struct files_ref_store *refs,
 			     const unsigned char *sha1, const char *logmsg,
 			     struct strbuf *err)
 {
-	assert_main_repository(&refs->base, "commit_ref_update");
+	files_assert_main_repository(refs, "commit_ref_update");
 
 	clear_loose_ref_cache(refs);
-	if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
+	if (files_log_ref_write(lock->ref_name, lock->old_oid.hash, sha1,
+				logmsg, 0, err)) {
 		char *old_msg = strbuf_detach(err, NULL);
 		strbuf_addf(err, "cannot update the ref '%s': %s",
 			    lock->ref_name, old_msg);
@@ -2964,7 +2952,7 @@ static int commit_ref_update(struct files_ref_store *refs,
 		if (head_ref && (head_flag & REF_ISSYMREF) &&
 		    !strcmp(head_ref, lock->ref_name)) {
 			struct strbuf log_err = STRBUF_INIT;
-			if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
+			if (files_log_ref_write("HEAD", lock->old_oid.hash, sha1,
 					  logmsg, 0, &log_err)) {
 				error("%s", log_err.buf);
 				strbuf_release(&log_err);
@@ -3003,7 +2991,8 @@ static void update_symref_reflog(struct ref_lock *lock, const char *refname,
 	struct strbuf err = STRBUF_INIT;
 	unsigned char new_sha1[20];
 	if (logmsg && !read_ref(target, new_sha1) &&
-	    log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
+	    files_log_ref_write(refname, lock->old_oid.hash, new_sha1,
+				logmsg, 0, &err)) {
 		error("%s", err.buf);
 		strbuf_release(&err);
 	}
@@ -3055,7 +3044,7 @@ static int files_create_symref(struct ref_store *ref_store,
 	return ret;
 }
 
-int set_worktree_head_symref(const char *gitdir, const char *target)
+int set_worktree_head_symref(const char *gitdir, const char *target, const char *logmsg)
 {
 	static struct lock_file head_lock;
 	struct ref_lock *lock;
@@ -3083,7 +3072,7 @@ int set_worktree_head_symref(const char *gitdir, const char *target)
 	lock->lk = &head_lock;
 	lock->ref_name = xstrdup(head_rel);
 
-	ret = create_symref_locked(lock, head_rel, target, NULL);
+	ret = create_symref_locked(lock, head_rel, target, logmsg);
 
 	unlock_ref(lock); /* will free lock */
 	strbuf_release(&head_path);
@@ -3113,16 +3102,17 @@ static int files_delete_reflog(struct ref_store *ref_store,
 
 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
 {
-	unsigned char osha1[20], nsha1[20];
+	struct object_id ooid, noid;
 	char *email_end, *message;
 	unsigned long timestamp;
 	int tz;
+	const char *p = sb->buf;
 
 	/* old SP new SP name <email> SP time TAB msg LF */
-	if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
-	    get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
-	    get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
-	    !(email_end = strchr(sb->buf + 82, '>')) ||
+	if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
+	    parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
+	    parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
+	    !(email_end = strchr(p, '>')) ||
 	    email_end[1] != ' ' ||
 	    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
 	    !message || message[0] != ' ' ||
@@ -3136,7 +3126,7 @@ static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *c
 		message += 6;
 	else
 		message += 7;
-	return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
+	return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
 }
 
 static char *find_beginning_of_line(char *bob, char *scan)
@@ -3560,7 +3550,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 	int ret;
 	struct ref_lock *lock;
 
-	assert_main_repository(&refs->base, "lock_ref_for_update");
+	files_assert_main_repository(refs, "lock_ref_for_update");
 
 	if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
 		update->flags |= REF_DELETING;
@@ -3778,9 +3768,11 @@ static int files_transaction_commit(struct ref_store *ref_store,
 
 		if (update->flags & REF_NEEDS_COMMIT ||
 		    update->flags & REF_LOG_ONLY) {
-			if (log_ref_write(lock->ref_name, lock->old_oid.hash,
-					  update->new_sha1,
-					  update->msg, update->flags, err)) {
+			if (files_log_ref_write(lock->ref_name,
+						lock->old_oid.hash,
+						update->new_sha1,
+						update->msg, update->flags,
+						err)) {
 				char *old_msg = strbuf_detach(err, NULL);
 
 				strbuf_addf(err, "cannot update the ref '%s': %s",
@@ -3810,9 +3802,14 @@ static int files_transaction_commit(struct ref_store *ref_store,
 
 		if (update->flags & REF_DELETING &&
 		    !(update->flags & REF_LOG_ONLY)) {
-			if (delete_ref_loose(lock, update->type, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
+			if (!(update->type & REF_ISPACKED) ||
+			    update->type & REF_ISSYMREF) {
+				/* It is a loose reference. */
+				if (unlink_or_msg(git_path("%s", lock->ref_name), err)) {
+					ret = TRANSACTION_GENERIC_ERROR;
+					goto cleanup;
+				}
+				update->flags |= REF_DELETED_LOOSE;
 			}
 
 			if (!(update->flags & REF_ISPRUNING))
@@ -3825,16 +3822,38 @@ static int files_transaction_commit(struct ref_store *ref_store,
 		ret = TRANSACTION_GENERIC_ERROR;
 		goto cleanup;
 	}
-	for_each_string_list_item(ref_to_delete, &refs_to_delete)
-		unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
+
+	/* Delete the reflogs of any references that were deleted: */
+	for_each_string_list_item(ref_to_delete, &refs_to_delete) {
+		if (!unlink_or_warn(git_path("logs/%s", ref_to_delete->string)))
+			try_remove_empty_parents(ref_to_delete->string,
+						 REMOVE_EMPTY_PARENTS_REFLOG);
+	}
+
 	clear_loose_ref_cache(refs);
 
 cleanup:
 	transaction->state = REF_TRANSACTION_CLOSED;
 
-	for (i = 0; i < transaction->nr; i++)
-		if (transaction->updates[i]->backend_data)
-			unlock_ref(transaction->updates[i]->backend_data);
+	for (i = 0; i < transaction->nr; i++) {
+		struct ref_update *update = transaction->updates[i];
+		struct ref_lock *lock = update->backend_data;
+
+		if (lock)
+			unlock_ref(lock);
+
+		if (update->flags & REF_DELETED_LOOSE) {
+			/*
+			 * The loose reference was deleted. Delete any
+			 * empty parent directories. (Note that this
+			 * can only work because we have already
+			 * removed the lockfile.)
+			 */
+			try_remove_empty_parents(update->refname,
+						 REMOVE_EMPTY_PARENTS_REF);
+		}
+	}
+
 	string_list_clear(&refs_to_delete, 0);
 	free(head_ref);
 	string_list_clear(&affected_refnames, 0);
@@ -3936,10 +3955,10 @@ struct expire_reflog_cb {
 	reflog_expiry_should_prune_fn *should_prune_fn;
 	void *policy_cb;
 	FILE *newlog;
-	unsigned char last_kept_sha1[20];
+	struct object_id last_kept_oid;
 };
 
-static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
+static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
 			     const char *email, unsigned long timestamp, int tz,
 			     const char *message, void *cb_data)
 {
@@ -3947,9 +3966,9 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
 
 	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
-		osha1 = cb->last_kept_sha1;
+		ooid = &cb->last_kept_oid;
 
-	if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
+	if ((*cb->should_prune_fn)(ooid->hash, noid->hash, email, timestamp, tz,
 				   message, policy_cb)) {
 		if (!cb->newlog)
 			printf("would prune %s", message);
@@ -3958,9 +3977,9 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 	} else {
 		if (cb->newlog) {
 			fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
-				sha1_to_hex(osha1), sha1_to_hex(nsha1),
+				oid_to_hex(ooid), oid_to_hex(noid),
 				email, timestamp, tz, message);
-			hashcpy(cb->last_kept_sha1, nsha1);
+			oidcpy(&cb->last_kept_oid, noid);
 		}
 		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
 			printf("keep %s", message);
@@ -4047,14 +4066,14 @@ static int files_reflog_expire(struct ref_store *ref_store,
 		 */
 		int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
 			!(type & REF_ISSYMREF) &&
-			!is_null_sha1(cb.last_kept_sha1);
+			!is_null_oid(&cb.last_kept_oid);
 
 		if (close_lock_file(&reflog_lock)) {
 			status |= error("couldn't write %s: %s", log_file,
 					strerror(errno));
 		} else if (update &&
 			   (write_in_full(get_lock_file_fd(lock->lk),
-				sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
+				oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
 			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
 			    close_ref(lock) < 0)) {
 			status |= error("couldn't write %s",