about summary refs log tree commit diff
path: root/third_party/git/refs/files-backend.c
diff options
context:
space:
mode:
Diffstat (limited to 'third_party/git/refs/files-backend.c')
-rw-r--r--third_party/git/refs/files-backend.c3198
1 files changed, 0 insertions, 3198 deletions
diff --git a/third_party/git/refs/files-backend.c b/third_party/git/refs/files-backend.c
deleted file mode 100644
index 04e85e70029b..000000000000
--- a/third_party/git/refs/files-backend.c
+++ /dev/null
@@ -1,3198 +0,0 @@
-#include "../cache.h"
-#include "../config.h"
-#include "../refs.h"
-#include "refs-internal.h"
-#include "ref-cache.h"
-#include "packed-backend.h"
-#include "../iterator.h"
-#include "../dir-iterator.h"
-#include "../lockfile.h"
-#include "../object.h"
-#include "../dir.h"
-#include "../chdir-notify.h"
-#include "worktree.h"
-
-/*
- * This backend uses the following flags in `ref_update::flags` for
- * internal bookkeeping purposes. Their numerical values must not
- * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW,
- * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in
- * `ref_update::flags`.
- */
-
-/*
- * Used as a flag in ref_update::flags when a loose ref is being
- * pruned. This flag must only be used when REF_NO_DEREF is set.
- */
-#define REF_IS_PRUNING (1 << 4)
-
-/*
- * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
- * refs (i.e., because the reference is about to be deleted anyway).
- */
-#define REF_DELETING (1 << 5)
-
-/*
- * Used as a flag in ref_update::flags when the lockfile needs to be
- * committed.
- */
-#define REF_NEEDS_COMMIT (1 << 6)
-
-/*
- * Used as a flag in ref_update::flags when the ref_update was via an
- * update to HEAD.
- */
-#define REF_UPDATE_VIA_HEAD (1 << 8)
-
-/*
- * Used as a flag in ref_update::flags when the loose reference has
- * been deleted.
- */
-#define REF_DELETED_LOOSE (1 << 9)
-
-struct ref_lock {
-	char *ref_name;
-	struct lock_file lk;
-	struct object_id old_oid;
-};
-
-struct files_ref_store {
-	struct ref_store base;
-	unsigned int store_flags;
-
-	char *gitcommondir;
-
-	struct ref_cache *loose;
-
-	struct ref_store *packed_ref_store;
-};
-
-static void clear_loose_ref_cache(struct files_ref_store *refs)
-{
-	if (refs->loose) {
-		free_ref_cache(refs->loose);
-		refs->loose = NULL;
-	}
-}
-
-/*
- * Create a new submodule ref cache and add it to the internal
- * set of caches.
- */
-static struct ref_store *files_ref_store_create(const char *gitdir,
-						unsigned int flags)
-{
-	struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
-	struct ref_store *ref_store = (struct ref_store *)refs;
-	struct strbuf sb = STRBUF_INIT;
-
-	ref_store->gitdir = xstrdup(gitdir);
-	base_ref_store_init(ref_store, &refs_be_files);
-	refs->store_flags = flags;
-
-	get_common_dir_noenv(&sb, gitdir);
-	refs->gitcommondir = strbuf_detach(&sb, NULL);
-	strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
-	refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
-	strbuf_release(&sb);
-
-	chdir_notify_reparent("files-backend $GIT_DIR", &refs->base.gitdir);
-	chdir_notify_reparent("files-backend $GIT_COMMONDIR",
-			      &refs->gitcommondir);
-
-	return ref_store;
-}
-
-/*
- * Die if refs is not the main ref store. caller is used in any
- * necessary error messages.
- */
-static void files_assert_main_repository(struct files_ref_store *refs,
-					 const char *caller)
-{
-	if (refs->store_flags & REF_STORE_MAIN)
-		return;
-
-	BUG("operation %s only allowed for main ref store", caller);
-}
-
-/*
- * Downcast ref_store to files_ref_store. Die if ref_store is not a
- * files_ref_store. required_flags is compared with ref_store's
- * store_flags to ensure the ref_store has all required capabilities.
- * "caller" is used in any necessary error messages.
- */
-static struct files_ref_store *files_downcast(struct ref_store *ref_store,
-					      unsigned int required_flags,
-					      const char *caller)
-{
-	struct files_ref_store *refs;
-
-	if (ref_store->be != &refs_be_files)
-		BUG("ref_store is type \"%s\" not \"files\" in %s",
-		    ref_store->be->name, caller);
-
-	refs = (struct files_ref_store *)ref_store;
-
-	if ((refs->store_flags & required_flags) != required_flags)
-		BUG("operation %s requires abilities 0x%x, but only have 0x%x",
-		    caller, required_flags, refs->store_flags);
-
-	return refs;
-}
-
-static void files_reflog_path_other_worktrees(struct files_ref_store *refs,
-					      struct strbuf *sb,
-					      const char *refname)
-{
-	const char *real_ref;
-	const char *worktree_name;
-	int length;
-
-	if (parse_worktree_ref(refname, &worktree_name, &length, &real_ref))
-		BUG("refname %s is not a other-worktree ref", refname);
-
-	if (worktree_name)
-		strbuf_addf(sb, "%s/worktrees/%.*s/logs/%s", refs->gitcommondir,
-			    length, worktree_name, real_ref);
-	else
-		strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir,
-			    real_ref);
-}
-
-static void files_reflog_path(struct files_ref_store *refs,
-			      struct strbuf *sb,
-			      const char *refname)
-{
-	switch (ref_type(refname)) {
-	case REF_TYPE_PER_WORKTREE:
-	case REF_TYPE_PSEUDOREF:
-		strbuf_addf(sb, "%s/logs/%s", refs->base.gitdir, refname);
-		break;
-	case REF_TYPE_OTHER_PSEUDOREF:
-	case REF_TYPE_MAIN_PSEUDOREF:
-		files_reflog_path_other_worktrees(refs, sb, refname);
-		break;
-	case REF_TYPE_NORMAL:
-		strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
-		break;
-	default:
-		BUG("unknown ref type %d of ref %s",
-		    ref_type(refname), refname);
-	}
-}
-
-static void files_ref_path(struct files_ref_store *refs,
-			   struct strbuf *sb,
-			   const char *refname)
-{
-	switch (ref_type(refname)) {
-	case REF_TYPE_PER_WORKTREE:
-	case REF_TYPE_PSEUDOREF:
-		strbuf_addf(sb, "%s/%s", refs->base.gitdir, refname);
-		break;
-	case REF_TYPE_MAIN_PSEUDOREF:
-		if (!skip_prefix(refname, "main-worktree/", &refname))
-			BUG("ref %s is not a main pseudoref", refname);
-		/* fallthrough */
-	case REF_TYPE_OTHER_PSEUDOREF:
-	case REF_TYPE_NORMAL:
-		strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
-		break;
-	default:
-		BUG("unknown ref type %d of ref %s",
-		    ref_type(refname), refname);
-	}
-}
-
-/*
- * Manually add refs/bisect, refs/rewritten and refs/worktree, which, being
- * per-worktree, might not appear in the directory listing for
- * refs/ in the main repo.
- */
-static void add_per_worktree_entries_to_dir(struct ref_dir *dir, const char *dirname)
-{
-	const char *prefixes[] = { "refs/bisect/", "refs/worktree/", "refs/rewritten/" };
-	int ip;
-
-	if (strcmp(dirname, "refs/"))
-		return;
-
-	for (ip = 0; ip < ARRAY_SIZE(prefixes); ip++) {
-		const char *prefix = prefixes[ip];
-		int prefix_len = strlen(prefix);
-		struct ref_entry *child_entry;
-		int pos;
-
-		pos = search_ref_dir(dir, prefix, prefix_len);
-		if (pos >= 0)
-			continue;
-		child_entry = create_dir_entry(dir->cache, prefix, prefix_len, 1);
-		add_entry_to_dir(dir, child_entry);
-	}
-}
-
-/*
- * Read the loose references from the namespace dirname into dir
- * (without recursing).  dirname must end with '/'.  dir must be the
- * directory entry corresponding to dirname.
- */
-static void loose_fill_ref_dir(struct ref_store *ref_store,
-			       struct ref_dir *dir, const char *dirname)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
-	DIR *d;
-	struct dirent *de;
-	int dirnamelen = strlen(dirname);
-	struct strbuf refname;
-	struct strbuf path = STRBUF_INIT;
-	size_t path_baselen;
-
-	files_ref_path(refs, &path, dirname);
-	path_baselen = path.len;
-
-	d = opendir(path.buf);
-	if (!d) {
-		strbuf_release(&path);
-		return;
-	}
-
-	strbuf_init(&refname, dirnamelen + 257);
-	strbuf_add(&refname, dirname, dirnamelen);
-
-	while ((de = readdir(d)) != NULL) {
-		struct object_id oid;
-		struct stat st;
-		int flag;
-
-		if (de->d_name[0] == '.')
-			continue;
-		if (ends_with(de->d_name, ".lock"))
-			continue;
-		strbuf_addstr(&refname, de->d_name);
-		strbuf_addstr(&path, de->d_name);
-		if (stat(path.buf, &st) < 0) {
-			; /* silently ignore */
-		} else if (S_ISDIR(st.st_mode)) {
-			strbuf_addch(&refname, '/');
-			add_entry_to_dir(dir,
-					 create_dir_entry(dir->cache, refname.buf,
-							  refname.len, 1));
-		} else {
-			if (!refs_resolve_ref_unsafe(&refs->base,
-						     refname.buf,
-						     RESOLVE_REF_READING,
-						     &oid, &flag)) {
-				oidclr(&oid);
-				flag |= REF_ISBROKEN;
-			} else if (is_null_oid(&oid)) {
-				/*
-				 * It is so astronomically unlikely
-				 * that null_oid is the OID of an
-				 * actual object that we consider its
-				 * appearance in a loose reference
-				 * file to be repo corruption
-				 * (probably due to a software bug).
-				 */
-				flag |= REF_ISBROKEN;
-			}
-
-			if (check_refname_format(refname.buf,
-						 REFNAME_ALLOW_ONELEVEL)) {
-				if (!refname_is_safe(refname.buf))
-					die("loose refname is dangerous: %s", refname.buf);
-				oidclr(&oid);
-				flag |= REF_BAD_NAME | REF_ISBROKEN;
-			}
-			add_entry_to_dir(dir,
-					 create_ref_entry(refname.buf, &oid, flag));
-		}
-		strbuf_setlen(&refname, dirnamelen);
-		strbuf_setlen(&path, path_baselen);
-	}
-	strbuf_release(&refname);
-	strbuf_release(&path);
-	closedir(d);
-
-	add_per_worktree_entries_to_dir(dir, dirname);
-}
-
-static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
-{
-	if (!refs->loose) {
-		/*
-		 * Mark the top-level directory complete because we
-		 * are about to read the only subdirectory that can
-		 * hold references:
-		 */
-		refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
-
-		/* We're going to fill the top level ourselves: */
-		refs->loose->root->flag &= ~REF_INCOMPLETE;
-
-		/*
-		 * Add an incomplete entry for "refs/" (to be filled
-		 * lazily):
-		 */
-		add_entry_to_dir(get_ref_dir(refs->loose->root),
-				 create_dir_entry(refs->loose, "refs/", 5, 1));
-	}
-	return refs->loose;
-}
-
-static int files_read_raw_ref(struct ref_store *ref_store,
-			      const char *refname, struct object_id *oid,
-			      struct strbuf *referent, unsigned int *type)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
-	struct strbuf sb_contents = STRBUF_INIT;
-	struct strbuf sb_path = STRBUF_INIT;
-	const char *path;
-	const char *buf;
-	struct stat st;
-	int fd;
-	int ret = -1;
-	int save_errno;
-	int remaining_retries = 3;
-
-	*type = 0;
-	strbuf_reset(&sb_path);
-
-	files_ref_path(refs, &sb_path, refname);
-
-	path = sb_path.buf;
-
-stat_ref:
-	/*
-	 * 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().
-	 *
-	 * We'll keep a count of the retries, though, just to avoid
-	 * any confusing situation sending us into an infinite loop.
-	 */
-
-	if (remaining_retries-- <= 0)
-		goto out;
-
-	if (lstat(path, &st) < 0) {
-		if (errno != ENOENT)
-			goto out;
-		if (refs_read_raw_ref(refs->packed_ref_store, refname,
-				      oid, referent, type)) {
-			errno = ENOENT;
-			goto out;
-		}
-		ret = 0;
-		goto out;
-	}
-
-	/* Follow "normalized" - ie "refs/.." symlinks by hand */
-	if (S_ISLNK(st.st_mode)) {
-		strbuf_reset(&sb_contents);
-		if (strbuf_readlink(&sb_contents, path, st.st_size) < 0) {
-			if (errno == ENOENT || errno == EINVAL)
-				/* inconsistent with lstat; retry */
-				goto stat_ref;
-			else
-				goto out;
-		}
-		if (starts_with(sb_contents.buf, "refs/") &&
-		    !check_refname_format(sb_contents.buf, 0)) {
-			strbuf_swap(&sb_contents, referent);
-			*type |= REF_ISSYMREF;
-			ret = 0;
-			goto out;
-		}
-		/*
-		 * It doesn't look like a refname; fall through to just
-		 * treating it like a non-symlink, and reading whatever it
-		 * points to.
-		 */
-	}
-
-	/* Is it a directory? */
-	if (S_ISDIR(st.st_mode)) {
-		/*
-		 * Even though there is a directory where the loose
-		 * ref is supposed to be, there could still be a
-		 * packed ref:
-		 */
-		if (refs_read_raw_ref(refs->packed_ref_store, refname,
-				      oid, referent, type)) {
-			errno = EISDIR;
-			goto out;
-		}
-		ret = 0;
-		goto out;
-	}
-
-	/*
-	 * Anything else, just open it and try to use it as
-	 * a ref
-	 */
-	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-		if (errno == ENOENT && !S_ISLNK(st.st_mode))
-			/* inconsistent with lstat; retry */
-			goto stat_ref;
-		else
-			goto out;
-	}
-	strbuf_reset(&sb_contents);
-	if (strbuf_read(&sb_contents, fd, 256) < 0) {
-		int save_errno = errno;
-		close(fd);
-		errno = save_errno;
-		goto out;
-	}
-	close(fd);
-	strbuf_rtrim(&sb_contents);
-	buf = sb_contents.buf;
-
-	ret = parse_loose_ref_contents(buf, oid, referent, type);
-
-out:
-	save_errno = errno;
-	strbuf_release(&sb_path);
-	strbuf_release(&sb_contents);
-	errno = save_errno;
-	return ret;
-}
-
-int parse_loose_ref_contents(const char *buf, struct object_id *oid,
-			     struct strbuf *referent, unsigned int *type)
-{
-	const char *p;
-	if (skip_prefix(buf, "ref:", &buf)) {
-		while (isspace(*buf))
-			buf++;
-
-		strbuf_reset(referent);
-		strbuf_addstr(referent, buf);
-		*type |= REF_ISSYMREF;
-		return 0;
-	}
-
-	/*
-	 * FETCH_HEAD has additional data after the sha.
-	 */
-	if (parse_oid_hex(buf, oid, &p) ||
-	    (*p != '\0' && !isspace(*p))) {
-		*type |= REF_ISBROKEN;
-		errno = EINVAL;
-		return -1;
-	}
-	return 0;
-}
-
-static void unlock_ref(struct ref_lock *lock)
-{
-	rollback_lock_file(&lock->lk);
-	free(lock->ref_name);
-	free(lock);
-}
-
-/*
- * Lock refname, without following symrefs, and set *lock_p to point
- * at a newly-allocated lock object. Fill in lock->old_oid, referent,
- * and type similarly to read_raw_ref().
- *
- * The caller must verify that refname is a "safe" reference name (in
- * the sense of refname_is_safe()) before calling this function.
- *
- * If the reference doesn't already exist, verify that refname doesn't
- * have a D/F conflict with any existing references. extras and skip
- * are passed to refs_verify_refname_available() for this check.
- *
- * If mustexist is not set and the reference is not found or is
- * broken, lock the reference anyway but clear old_oid.
- *
- * Return 0 on success. On failure, write an error message to err and
- * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
- *
- * Implementation note: This function is basically
- *
- *     lock reference
- *     read_raw_ref()
- *
- * but it includes a lot more code to
- * - Deal with possible races with other processes
- * - Avoid calling refs_verify_refname_available() when it can be
- *   avoided, namely if we were successfully able to read the ref
- * - Generate informative error messages in the case of failure
- */
-static int lock_raw_ref(struct files_ref_store *refs,
-			const char *refname, int mustexist,
-			const struct string_list *extras,
-			const struct string_list *skip,
-			struct ref_lock **lock_p,
-			struct strbuf *referent,
-			unsigned int *type,
-			struct strbuf *err)
-{
-	struct ref_lock *lock;
-	struct strbuf ref_file = STRBUF_INIT;
-	int attempts_remaining = 3;
-	int ret = TRANSACTION_GENERIC_ERROR;
-
-	assert(err);
-	files_assert_main_repository(refs, "lock_raw_ref");
-
-	*type = 0;
-
-	/* First lock the file so it can't change out from under us. */
-
-	*lock_p = lock = xcalloc(1, sizeof(*lock));
-
-	lock->ref_name = xstrdup(refname);
-	files_ref_path(refs, &ref_file, refname);
-
-retry:
-	switch (safe_create_leading_directories(ref_file.buf)) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_EXISTS:
-		/*
-		 * Suppose refname is "refs/foo/bar". We just failed
-		 * to create the containing directory, "refs/foo",
-		 * because there was a non-directory in the way. This
-		 * indicates a D/F conflict, probably because of
-		 * another reference such as "refs/foo". There is no
-		 * reason to expect this error to be transitory.
-		 */
-		if (refs_verify_refname_available(&refs->base, refname,
-						  extras, skip, err)) {
-			if (mustexist) {
-				/*
-				 * To the user the relevant error is
-				 * that the "mustexist" reference is
-				 * missing:
-				 */
-				strbuf_reset(err);
-				strbuf_addf(err, "unable to resolve reference '%s'",
-					    refname);
-			} else {
-				/*
-				 * The error message set by
-				 * refs_verify_refname_available() is
-				 * OK.
-				 */
-				ret = TRANSACTION_NAME_CONFLICT;
-			}
-		} else {
-			/*
-			 * The file that is in the way isn't a loose
-			 * reference. Report it as a low-level
-			 * failure.
-			 */
-			strbuf_addf(err, "unable to create lock file %s.lock; "
-				    "non-directory in the way",
-				    ref_file.buf);
-		}
-		goto error_return;
-	case SCLD_VANISHED:
-		/* Maybe another process was tidying up. Try again. */
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		strbuf_addf(err, "unable to create directory for %s",
-			    ref_file.buf);
-		goto error_return;
-	}
-
-	if (hold_lock_file_for_update_timeout(
-			    &lock->lk, ref_file.buf, LOCK_NO_DEREF,
-			    get_files_ref_lock_timeout_ms()) < 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_message(ref_file.buf, errno, err);
-			goto error_return;
-		}
-	}
-
-	/*
-	 * Now we hold the lock and can read the reference without
-	 * fear that its value will change.
-	 */
-
-	if (files_read_raw_ref(&refs->base, refname,
-			       &lock->old_oid, referent, type)) {
-		if (errno == ENOENT) {
-			if (mustexist) {
-				/* Garden variety missing reference. */
-				strbuf_addf(err, "unable to resolve reference '%s'",
-					    refname);
-				goto error_return;
-			} else {
-				/*
-				 * Reference is missing, but that's OK. We
-				 * know that there is not a conflict with
-				 * another loose reference because
-				 * (supposing that we are trying to lock
-				 * reference "refs/foo/bar"):
-				 *
-				 * - We were successfully able to create
-				 *   the lockfile refs/foo/bar.lock, so we
-				 *   know there cannot be a loose reference
-				 *   named "refs/foo".
-				 *
-				 * - We got ENOENT and not EISDIR, so we
-				 *   know that there cannot be a loose
-				 *   reference named "refs/foo/bar/baz".
-				 */
-			}
-		} else if (errno == EISDIR) {
-			/*
-			 * There is a directory in the way. It might have
-			 * contained references that have been deleted. If
-			 * we don't require that the reference already
-			 * exists, try to remove the directory so that it
-			 * doesn't cause trouble when we want to rename the
-			 * lockfile into place later.
-			 */
-			if (mustexist) {
-				/* Garden variety missing reference. */
-				strbuf_addf(err, "unable to resolve reference '%s'",
-					    refname);
-				goto error_return;
-			} else if (remove_dir_recursively(&ref_file,
-							  REMOVE_DIR_EMPTY_ONLY)) {
-				if (refs_verify_refname_available(
-						    &refs->base, refname,
-						    extras, skip, err)) {
-					/*
-					 * The error message set by
-					 * verify_refname_available() is OK.
-					 */
-					ret = TRANSACTION_NAME_CONFLICT;
-					goto error_return;
-				} else {
-					/*
-					 * We can't delete the directory,
-					 * but we also don't know of any
-					 * references that it should
-					 * contain.
-					 */
-					strbuf_addf(err, "there is a non-empty directory '%s' "
-						    "blocking reference '%s'",
-						    ref_file.buf, refname);
-					goto error_return;
-				}
-			}
-		} else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
-			strbuf_addf(err, "unable to resolve reference '%s': "
-				    "reference broken", refname);
-			goto error_return;
-		} else {
-			strbuf_addf(err, "unable to resolve reference '%s': %s",
-				    refname, strerror(errno));
-			goto error_return;
-		}
-
-		/*
-		 * If the ref did not exist and we are creating it,
-		 * make sure there is no existing packed ref that
-		 * conflicts with refname:
-		 */
-		if (refs_verify_refname_available(
-				    refs->packed_ref_store, refname,
-				    extras, skip, err))
-			goto error_return;
-	}
-
-	ret = 0;
-	goto out;
-
-error_return:
-	unlock_ref(lock);
-	*lock_p = NULL;
-
-out:
-	strbuf_release(&ref_file);
-	return ret;
-}
-
-struct files_ref_iterator {
-	struct ref_iterator base;
-
-	struct ref_iterator *iter0;
-	unsigned int flags;
-};
-
-static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
-{
-	struct files_ref_iterator *iter =
-		(struct files_ref_iterator *)ref_iterator;
-	int ok;
-
-	while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
-		if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
-		    ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
-			continue;
-
-		if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
-		    !ref_resolves_to_object(iter->iter0->refname,
-					    iter->iter0->oid,
-					    iter->iter0->flags))
-			continue;
-
-		iter->base.refname = iter->iter0->refname;
-		iter->base.oid = iter->iter0->oid;
-		iter->base.flags = iter->iter0->flags;
-		return ITER_OK;
-	}
-
-	iter->iter0 = NULL;
-	if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-		ok = ITER_ERROR;
-
-	return ok;
-}
-
-static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
-				   struct object_id *peeled)
-{
-	struct files_ref_iterator *iter =
-		(struct files_ref_iterator *)ref_iterator;
-
-	return ref_iterator_peel(iter->iter0, peeled);
-}
-
-static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
-{
-	struct files_ref_iterator *iter =
-		(struct files_ref_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->iter0)
-		ok = ref_iterator_abort(iter->iter0);
-
-	base_ref_iterator_free(ref_iterator);
-	return ok;
-}
-
-static struct ref_iterator_vtable files_ref_iterator_vtable = {
-	files_ref_iterator_advance,
-	files_ref_iterator_peel,
-	files_ref_iterator_abort
-};
-
-static struct ref_iterator *files_ref_iterator_begin(
-		struct ref_store *ref_store,
-		const char *prefix, unsigned int flags)
-{
-	struct files_ref_store *refs;
-	struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
-	struct files_ref_iterator *iter;
-	struct ref_iterator *ref_iterator;
-	unsigned int required_flags = REF_STORE_READ;
-
-	if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
-		required_flags |= REF_STORE_ODB;
-
-	refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
-
-	/*
-	 * We must make sure that all loose refs are read before
-	 * accessing the packed-refs file; this avoids a race
-	 * condition if loose refs are migrated to the packed-refs
-	 * file by a simultaneous process, but our in-memory view is
-	 * from before the migration. We ensure this as follows:
-	 * First, we call start the loose refs iteration with its
-	 * `prime_ref` argument set to true. This causes the loose
-	 * references in the subtree to be pre-read into the cache.
-	 * (If they've already been read, that's OK; we only need to
-	 * guarantee that they're read before the packed refs, not
-	 * *how much* before.) After that, we call
-	 * packed_ref_iterator_begin(), which internally checks
-	 * whether the packed-ref cache is up to date with what is on
-	 * disk, and re-reads it if not.
-	 */
-
-	loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
-					      prefix, 1);
-
-	/*
-	 * The packed-refs file might contain broken references, for
-	 * example an old version of a reference that points at an
-	 * object that has since been garbage-collected. This is OK as
-	 * long as there is a corresponding loose reference that
-	 * overrides it, and we don't want to emit an error message in
-	 * this case. So ask the packed_ref_store for all of its
-	 * references, and (if needed) do our own check for broken
-	 * ones in files_ref_iterator_advance(), after we have merged
-	 * the packed and loose references.
-	 */
-	packed_iter = refs_ref_iterator_begin(
-			refs->packed_ref_store, prefix, 0,
-			DO_FOR_EACH_INCLUDE_BROKEN);
-
-	overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
-
-	iter = xcalloc(1, sizeof(*iter));
-	ref_iterator = &iter->base;
-	base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
-			       overlay_iter->ordered);
-	iter->iter0 = overlay_iter;
-	iter->flags = flags;
-
-	return ref_iterator;
-}
-
-/*
- * Verify that the reference locked by lock has the value old_oid
- * (unless it is NULL).  Fail if the reference doesn't exist and
- * mustexist is set. Return 0 on success. On error, write an error
- * message to err, set errno, and return a negative value.
- */
-static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
-		       const struct object_id *old_oid, int mustexist,
-		       struct strbuf *err)
-{
-	assert(err);
-
-	if (refs_read_ref_full(ref_store, lock->ref_name,
-			       mustexist ? RESOLVE_REF_READING : 0,
-			       &lock->old_oid, NULL)) {
-		if (old_oid) {
-			int save_errno = errno;
-			strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
-			errno = save_errno;
-			return -1;
-		} else {
-			oidclr(&lock->old_oid);
-			return 0;
-		}
-	}
-	if (old_oid && !oideq(&lock->old_oid, old_oid)) {
-		strbuf_addf(err, "ref '%s' is at %s but expected %s",
-			    lock->ref_name,
-			    oid_to_hex(&lock->old_oid),
-			    oid_to_hex(old_oid));
-		errno = EBUSY;
-		return -1;
-	}
-	return 0;
-}
-
-static int remove_empty_directories(struct strbuf *path)
-{
-	/*
-	 * we want to create a file but there is a directory there;
-	 * if that is an empty directory (or a directory that contains
-	 * only empty directories), remove them.
-	 */
-	return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
-}
-
-static int create_reflock(const char *path, void *cb)
-{
-	struct lock_file *lk = cb;
-
-	return hold_lock_file_for_update_timeout(
-			lk, path, LOCK_NO_DEREF,
-			get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
-}
-
-/*
- * Locks a ref returning the lock on success and NULL on failure.
- * On failure errno is set to something meaningful.
- */
-static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
-					   const char *refname,
-					   const struct object_id *old_oid,
-					   const struct string_list *extras,
-					   const struct string_list *skip,
-					   unsigned int flags, int *type,
-					   struct strbuf *err)
-{
-	struct strbuf ref_file = STRBUF_INIT;
-	struct ref_lock *lock;
-	int last_errno = 0;
-	int mustexist = (old_oid && !is_null_oid(old_oid));
-	int resolve_flags = RESOLVE_REF_NO_RECURSE;
-	int resolved;
-
-	files_assert_main_repository(refs, "lock_ref_oid_basic");
-	assert(err);
-
-	lock = xcalloc(1, sizeof(struct ref_lock));
-
-	if (mustexist)
-		resolve_flags |= RESOLVE_REF_READING;
-	if (flags & REF_DELETING)
-		resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
-
-	files_ref_path(refs, &ref_file, refname);
-	resolved = !!refs_resolve_ref_unsafe(&refs->base,
-					     refname, resolve_flags,
-					     &lock->old_oid, type);
-	if (!resolved && errno == EISDIR) {
-		/*
-		 * we are trying to lock foo but we used to
-		 * have foo/bar which now does not exist;
-		 * it is normal for the empty directory 'foo'
-		 * to remain.
-		 */
-		if (remove_empty_directories(&ref_file)) {
-			last_errno = errno;
-			if (!refs_verify_refname_available(
-					    &refs->base,
-					    refname, extras, skip, err))
-				strbuf_addf(err, "there are still refs under '%s'",
-					    refname);
-			goto error_return;
-		}
-		resolved = !!refs_resolve_ref_unsafe(&refs->base,
-						     refname, resolve_flags,
-						     &lock->old_oid, type);
-	}
-	if (!resolved) {
-		last_errno = errno;
-		if (last_errno != ENOTDIR ||
-		    !refs_verify_refname_available(&refs->base, refname,
-						   extras, skip, err))
-			strbuf_addf(err, "unable to resolve reference '%s': %s",
-				    refname, strerror(last_errno));
-
-		goto error_return;
-	}
-
-	/*
-	 * If the ref did not exist and we are creating it, make sure
-	 * there is no existing packed ref whose name begins with our
-	 * refname, nor a packed ref whose name is a proper prefix of
-	 * our refname.
-	 */
-	if (is_null_oid(&lock->old_oid) &&
-	    refs_verify_refname_available(refs->packed_ref_store, refname,
-					  extras, skip, err)) {
-		last_errno = ENOTDIR;
-		goto error_return;
-	}
-
-	lock->ref_name = xstrdup(refname);
-
-	if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
-		last_errno = errno;
-		unable_to_lock_message(ref_file.buf, errno, err);
-		goto error_return;
-	}
-
-	if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) {
-		last_errno = errno;
-		goto error_return;
-	}
-	goto out;
-
- error_return:
-	unlock_ref(lock);
-	lock = NULL;
-
- out:
-	strbuf_release(&ref_file);
-	errno = last_errno;
-	return lock;
-}
-
-struct ref_to_prune {
-	struct ref_to_prune *next;
-	struct object_id oid;
-	char name[FLEX_ARRAY];
-};
-
-enum {
-	REMOVE_EMPTY_PARENTS_REF = 0x01,
-	REMOVE_EMPTY_PARENTS_REFLOG = 0x02
-};
-
-/*
- * 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(struct files_ref_store *refs,
-				     const char *refname,
-				     unsigned int flags)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct strbuf sb = STRBUF_INIT;
-	char *p, *q;
-	int i;
-
-	strbuf_addstr(&buf, refname);
-	p = buf.buf;
-	for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
-		while (*p && *p != '/')
-			p++;
-		/* tolerate duplicate slashes; see check_refname_format() */
-		while (*p == '/')
-			p++;
-	}
-	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;
-		strbuf_setlen(&buf, q - buf.buf);
-
-		strbuf_reset(&sb);
-		files_ref_path(refs, &sb, buf.buf);
-		if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
-			flags &= ~REMOVE_EMPTY_PARENTS_REF;
-
-		strbuf_reset(&sb);
-		files_reflog_path(refs, &sb, buf.buf);
-		if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
-			flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
-	}
-	strbuf_release(&buf);
-	strbuf_release(&sb);
-}
-
-/* make sure nobody touched the ref, and unlink */
-static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
-{
-	struct ref_transaction *transaction;
-	struct strbuf err = STRBUF_INIT;
-	int ret = -1;
-
-	if (check_refname_format(r->name, 0))
-		return;
-
-	transaction = ref_store_transaction_begin(&refs->base, &err);
-	if (!transaction)
-		goto cleanup;
-	ref_transaction_add_update(
-			transaction, r->name,
-			REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
-			&null_oid, &r->oid, NULL);
-	if (ref_transaction_commit(transaction, &err))
-		goto cleanup;
-
-	ret = 0;
-
-cleanup:
-	if (ret)
-		error("%s", err.buf);
-	strbuf_release(&err);
-	ref_transaction_free(transaction);
-	return;
-}
-
-/*
- * Prune the loose versions of the references in the linked list
- * `*refs_to_prune`, freeing the entries in the list as we go.
- */
-static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
-{
-	while (*refs_to_prune) {
-		struct ref_to_prune *r = *refs_to_prune;
-		*refs_to_prune = r->next;
-		prune_ref(refs, r);
-		free(r);
-	}
-}
-
-/*
- * Return true if the specified reference should be packed.
- */
-static int should_pack_ref(const char *refname,
-			   const struct object_id *oid, unsigned int ref_flags,
-			   unsigned int pack_flags)
-{
-	/* Do not pack per-worktree refs: */
-	if (ref_type(refname) != REF_TYPE_NORMAL)
-		return 0;
-
-	/* Do not pack non-tags unless PACK_REFS_ALL is set: */
-	if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
-		return 0;
-
-	/* Do not pack symbolic refs: */
-	if (ref_flags & REF_ISSYMREF)
-		return 0;
-
-	/* Do not pack broken refs: */
-	if (!ref_resolves_to_object(refname, oid, ref_flags))
-		return 0;
-
-	return 1;
-}
-
-static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
-			       "pack_refs");
-	struct ref_iterator *iter;
-	int ok;
-	struct ref_to_prune *refs_to_prune = NULL;
-	struct strbuf err = STRBUF_INIT;
-	struct ref_transaction *transaction;
-
-	transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
-	if (!transaction)
-		return -1;
-
-	packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
-
-	iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
-	while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
-		/*
-		 * If the loose reference can be packed, add an entry
-		 * in the packed ref cache. If the reference should be
-		 * pruned, also add it to refs_to_prune.
-		 */
-		if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
-				     flags))
-			continue;
-
-		/*
-		 * Add a reference creation for this reference to the
-		 * packed-refs transaction:
-		 */
-		if (ref_transaction_update(transaction, iter->refname,
-					   iter->oid, NULL,
-					   REF_NO_DEREF, NULL, &err))
-			die("failure preparing to create packed reference %s: %s",
-			    iter->refname, err.buf);
-
-		/* Schedule the loose reference for pruning if requested. */
-		if ((flags & PACK_REFS_PRUNE)) {
-			struct ref_to_prune *n;
-			FLEX_ALLOC_STR(n, name, iter->refname);
-			oidcpy(&n->oid, iter->oid);
-			n->next = refs_to_prune;
-			refs_to_prune = n;
-		}
-	}
-	if (ok != ITER_DONE)
-		die("error while iterating over references");
-
-	if (ref_transaction_commit(transaction, &err))
-		die("unable to write new packed-refs: %s", err.buf);
-
-	ref_transaction_free(transaction);
-
-	packed_refs_unlock(refs->packed_ref_store);
-
-	prune_refs(refs, &refs_to_prune);
-	strbuf_release(&err);
-	return 0;
-}
-
-static int files_delete_refs(struct ref_store *ref_store, const char *msg,
-			     struct string_list *refnames, unsigned int flags)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
-	struct strbuf err = STRBUF_INIT;
-	int i, result = 0;
-
-	if (!refnames->nr)
-		return 0;
-
-	if (packed_refs_lock(refs->packed_ref_store, 0, &err))
-		goto error;
-
-	if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
-		packed_refs_unlock(refs->packed_ref_store);
-		goto error;
-	}
-
-	packed_refs_unlock(refs->packed_ref_store);
-
-	for (i = 0; i < refnames->nr; i++) {
-		const char *refname = refnames->items[i].string;
-
-		if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
-			result |= error(_("could not remove reference %s"), refname);
-	}
-
-	strbuf_release(&err);
-	return result;
-
-error:
-	/*
-	 * 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);
-
-	strbuf_release(&err);
-	return -1;
-}
-
-/*
- * People using contrib's git-new-workdir have .git/logs/refs ->
- * /some/other/path/.git/logs/refs, and that may live on another device.
- *
- * IOW, to avoid cross device rename errors, the temporary renamed log must
- * live into logs/refs.
- */
-#define TMP_RENAMED_LOG  "refs/.tmp-renamed-log"
-
-struct rename_cb {
-	const char *tmp_renamed_log;
-	int true_errno;
-};
-
-static int rename_tmp_log_callback(const char *path, void *cb_data)
-{
-	struct rename_cb *cb = cb_data;
-
-	if (rename(cb->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.
-		 */
-		cb->true_errno = errno;
-		if (errno == ENOTDIR)
-			errno = EISDIR;
-		return -1;
-	} else {
-		return 0;
-	}
-}
-
-static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
-{
-	struct strbuf path = STRBUF_INIT;
-	struct strbuf tmp = STRBUF_INIT;
-	struct rename_cb cb;
-	int ret;
-
-	files_reflog_path(refs, &path, newrefname);
-	files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
-	cb.tmp_renamed_log = tmp.buf;
-	ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
-	if (ret) {
-		if (errno == EISDIR)
-			error("directory not empty: %s", path.buf);
-		else
-			error("unable to move logfile %s to %s: %s",
-			      tmp.buf, path.buf,
-			      strerror(cb.true_errno));
-	}
-
-	strbuf_release(&path);
-	strbuf_release(&tmp);
-	return ret;
-}
-
-static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const struct object_id *oid, struct strbuf *err);
-static int commit_ref_update(struct files_ref_store *refs,
-			     struct ref_lock *lock,
-			     const struct object_id *oid, const char *logmsg,
-			     struct strbuf *err);
-
-static int files_copy_or_rename_ref(struct ref_store *ref_store,
-			    const char *oldrefname, const char *newrefname,
-			    const char *logmsg, int copy)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
-	struct object_id orig_oid;
-	int flag = 0, logmoved = 0;
-	struct ref_lock *lock;
-	struct stat loginfo;
-	struct strbuf sb_oldref = STRBUF_INIT;
-	struct strbuf sb_newref = STRBUF_INIT;
-	struct strbuf tmp_renamed_log = STRBUF_INIT;
-	int log, ret;
-	struct strbuf err = STRBUF_INIT;
-
-	files_reflog_path(refs, &sb_oldref, oldrefname);
-	files_reflog_path(refs, &sb_newref, newrefname);
-	files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
-
-	log = !lstat(sb_oldref.buf, &loginfo);
-	if (log && S_ISLNK(loginfo.st_mode)) {
-		ret = error("reflog for %s is a symlink", oldrefname);
-		goto out;
-	}
-
-	if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
-				     RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-				&orig_oid, &flag)) {
-		ret = error("refname %s not found", oldrefname);
-		goto out;
-	}
-
-	if (flag & REF_ISSYMREF) {
-		if (copy)
-			ret = error("refname %s is a symbolic ref, copying it is not supported",
-				    oldrefname);
-		else
-			ret = error("refname %s is a symbolic ref, renaming it is not supported",
-				    oldrefname);
-		goto out;
-	}
-	if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
-		ret = 1;
-		goto out;
-	}
-
-	if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
-		ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
-			    oldrefname, strerror(errno));
-		goto out;
-	}
-
-	if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
-		ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
-			    oldrefname, strerror(errno));
-		goto out;
-	}
-
-	if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
-			    &orig_oid, REF_NO_DEREF)) {
-		error("unable to delete old %s", oldrefname);
-		goto rollback;
-	}
-
-	/*
-	 * Since we are doing a shallow lookup, oid is not the
-	 * correct value to pass to delete_ref as old_oid. But that
-	 * doesn't matter, because an old_oid check wouldn't add to
-	 * the safety anyway; we want to delete the reference whatever
-	 * its current value.
-	 */
-	if (!copy && !refs_read_ref_full(&refs->base, newrefname,
-				RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-				NULL, NULL) &&
-	    refs_delete_ref(&refs->base, NULL, newrefname,
-			    NULL, REF_NO_DEREF)) {
-		if (errno == EISDIR) {
-			struct strbuf path = STRBUF_INIT;
-			int result;
-
-			files_ref_path(refs, &path, newrefname);
-			result = remove_empty_directories(&path);
-			strbuf_release(&path);
-
-			if (result) {
-				error("Directory not empty: %s", newrefname);
-				goto rollback;
-			}
-		} else {
-			error("unable to delete existing %s", newrefname);
-			goto rollback;
-		}
-	}
-
-	if (log && rename_tmp_log(refs, newrefname))
-		goto rollback;
-
-	logmoved = log;
-
-	lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL,
-				  REF_NO_DEREF, NULL, &err);
-	if (!lock) {
-		if (copy)
-			error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
-		else
-			error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
-		strbuf_release(&err);
-		goto rollback;
-	}
-	oidcpy(&lock->old_oid, &orig_oid);
-
-	if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
-	    commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
-		error("unable to write current sha1 into %s: %s", newrefname, err.buf);
-		strbuf_release(&err);
-		goto rollback;
-	}
-
-	ret = 0;
-	goto out;
-
- rollback:
-	lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL,
-				  REF_NO_DEREF, NULL, &err);
-	if (!lock) {
-		error("unable to lock %s for rollback: %s", oldrefname, err.buf);
-		strbuf_release(&err);
-		goto rollbacklog;
-	}
-
-	flag = log_all_ref_updates;
-	log_all_ref_updates = LOG_REFS_NONE;
-	if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
-	    commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
-		error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
-		strbuf_release(&err);
-	}
-	log_all_ref_updates = flag;
-
- rollbacklog:
-	if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
-		error("unable to restore logfile %s from %s: %s",
-			oldrefname, newrefname, strerror(errno));
-	if (!logmoved && log &&
-	    rename(tmp_renamed_log.buf, sb_oldref.buf))
-		error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-	ret = 1;
- out:
-	strbuf_release(&sb_newref);
-	strbuf_release(&sb_oldref);
-	strbuf_release(&tmp_renamed_log);
-
-	return ret;
-}
-
-static int files_rename_ref(struct ref_store *ref_store,
-			    const char *oldrefname, const char *newrefname,
-			    const char *logmsg)
-{
-	return files_copy_or_rename_ref(ref_store, oldrefname,
-				 newrefname, logmsg, 0);
-}
-
-static int files_copy_ref(struct ref_store *ref_store,
-			    const char *oldrefname, const char *newrefname,
-			    const char *logmsg)
-{
-	return files_copy_or_rename_ref(ref_store, oldrefname,
-				 newrefname, logmsg, 1);
-}
-
-static int close_ref_gently(struct ref_lock *lock)
-{
-	if (close_lock_file_gently(&lock->lk))
-		return -1;
-	return 0;
-}
-
-static int commit_ref(struct ref_lock *lock)
-{
-	char *path = get_locked_file_path(&lock->lk);
-	struct stat st;
-
-	if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
-		/*
-		 * There is a directory at the path we want to rename
-		 * the lockfile to. Hopefully it is empty; try to
-		 * delete it.
-		 */
-		size_t len = strlen(path);
-		struct strbuf sb_path = STRBUF_INIT;
-
-		strbuf_attach(&sb_path, path, len, len);
-
-		/*
-		 * If this fails, commit_lock_file() will also fail
-		 * and will report the problem.
-		 */
-		remove_empty_directories(&sb_path);
-		strbuf_release(&sb_path);
-	} else {
-		free(path);
-	}
-
-	if (commit_lock_file(&lock->lk))
-		return -1;
-	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, 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(struct files_ref_store *refs,
-			 const char *refname, int force_create,
-			 int *logfd, struct strbuf *err)
-{
-	struct strbuf logfile_sb = STRBUF_INIT;
-	char *logfile;
-
-	files_reflog_path(refs, &logfile_sb, refname);
-	logfile = strbuf_detach(&logfile_sb, NULL);
-
-	if (force_create || should_autocreate_reflog(refname)) {
-		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));
-
-			goto error;
-		}
-	} 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;
-			}
-		}
-	}
-
-	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)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
-	int fd;
-
-	if (log_ref_setup(refs, refname, force_create, &fd, err))
-		return -1;
-
-	if (fd >= 0)
-		close(fd);
-
-	return 0;
-}
-
-static int log_ref_write_fd(int fd, const struct object_id *old_oid,
-			    const struct object_id *new_oid,
-			    const char *committer, const char *msg)
-{
-	struct strbuf sb = STRBUF_INIT;
-	int ret = 0;
-
-	strbuf_addf(&sb, "%s %s %s", oid_to_hex(old_oid), oid_to_hex(new_oid), committer);
-	if (msg && *msg) {
-		strbuf_addch(&sb, '\t');
-		strbuf_addstr(&sb, msg);
-	}
-	strbuf_addch(&sb, '\n');
-	if (write_in_full(fd, sb.buf, sb.len) < 0)
-		ret = -1;
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int files_log_ref_write(struct files_ref_store *refs,
-			       const char *refname, const struct object_id *old_oid,
-			       const struct object_id *new_oid, const char *msg,
-			       int flags, struct strbuf *err)
-{
-	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(refs, refname,
-			       flags & REF_FORCE_CREATE_REFLOG,
-			       &logfd, err);
-
-	if (result)
-		return result;
-
-	if (logfd < 0)
-		return 0;
-	result = log_ref_write_fd(logfd, old_oid, new_oid,
-				  git_committer_info(0), msg);
-	if (result) {
-		struct strbuf sb = STRBUF_INIT;
-		int save_errno = errno;
-
-		files_reflog_path(refs, &sb, refname);
-		strbuf_addf(err, "unable to append to '%s': %s",
-			    sb.buf, strerror(save_errno));
-		strbuf_release(&sb);
-		close(logfd);
-		return -1;
-	}
-	if (close(logfd)) {
-		struct strbuf sb = STRBUF_INIT;
-		int save_errno = errno;
-
-		files_reflog_path(refs, &sb, refname);
-		strbuf_addf(err, "unable to append to '%s': %s",
-			    sb.buf, strerror(save_errno));
-		strbuf_release(&sb);
-		return -1;
-	}
-	return 0;
-}
-
-/*
- * Write oid into the open lockfile, then close the lockfile. On
- * errors, rollback the lockfile, fill in *err and return -1.
- */
-static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const struct object_id *oid, struct strbuf *err)
-{
-	static char term = '\n';
-	struct object *o;
-	int fd;
-
-	o = parse_object(the_repository, oid);
-	if (!o) {
-		strbuf_addf(err,
-			    "trying to write ref '%s' with nonexistent object %s",
-			    lock->ref_name, oid_to_hex(oid));
-		unlock_ref(lock);
-		return -1;
-	}
-	if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
-		strbuf_addf(err,
-			    "trying to write non-commit object %s to branch '%s'",
-			    oid_to_hex(oid), lock->ref_name);
-		unlock_ref(lock);
-		return -1;
-	}
-	fd = get_lock_file_fd(&lock->lk);
-	if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
-	    write_in_full(fd, &term, 1) < 0 ||
-	    close_ref_gently(lock) < 0) {
-		strbuf_addf(err,
-			    "couldn't write '%s'", get_lock_file_path(&lock->lk));
-		unlock_ref(lock);
-		return -1;
-	}
-	return 0;
-}
-
-/*
- * Commit a change to a loose reference that has already been written
- * to the loose reference lockfile. Also update the reflogs if
- * necessary, using the specified lockmsg (which can be NULL).
- */
-static int commit_ref_update(struct files_ref_store *refs,
-			     struct ref_lock *lock,
-			     const struct object_id *oid, const char *logmsg,
-			     struct strbuf *err)
-{
-	files_assert_main_repository(refs, "commit_ref_update");
-
-	clear_loose_ref_cache(refs);
-	if (files_log_ref_write(refs, lock->ref_name,
-				&lock->old_oid, oid,
-				logmsg, 0, err)) {
-		char *old_msg = strbuf_detach(err, NULL);
-		strbuf_addf(err, "cannot update the ref '%s': %s",
-			    lock->ref_name, old_msg);
-		free(old_msg);
-		unlock_ref(lock);
-		return -1;
-	}
-
-	if (strcmp(lock->ref_name, "HEAD") != 0) {
-		/*
-		 * Special hack: If a branch is updated directly and HEAD
-		 * points to it (may happen on the remote side of a push
-		 * for example) then logically the HEAD reflog should be
-		 * updated too.
-		 * A generic solution implies reverse symref information,
-		 * but finding all symrefs pointing to the given branch
-		 * would be rather costly for this rare event (the direct
-		 * update of a branch) to be worth it.  So let's cheat and
-		 * check with HEAD only which should cover 99% of all usage
-		 * scenarios (even 100% of the default ones).
-		 */
-		int head_flag;
-		const char *head_ref;
-
-		head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
-						   RESOLVE_REF_READING,
-						   NULL, &head_flag);
-		if (head_ref && (head_flag & REF_ISSYMREF) &&
-		    !strcmp(head_ref, lock->ref_name)) {
-			struct strbuf log_err = STRBUF_INIT;
-			if (files_log_ref_write(refs, "HEAD",
-						&lock->old_oid, oid,
-						logmsg, 0, &log_err)) {
-				error("%s", log_err.buf);
-				strbuf_release(&log_err);
-			}
-		}
-	}
-
-	if (commit_ref(lock)) {
-		strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
-		unlock_ref(lock);
-		return -1;
-	}
-
-	unlock_ref(lock);
-	return 0;
-}
-
-static int create_ref_symlink(struct ref_lock *lock, const char *target)
-{
-	int ret = -1;
-#ifndef NO_SYMLINK_HEAD
-	char *ref_path = get_locked_file_path(&lock->lk);
-	unlink(ref_path);
-	ret = symlink(target, ref_path);
-	free(ref_path);
-
-	if (ret)
-		fprintf(stderr, "no symlink - falling back to symbolic ref\n");
-#endif
-	return ret;
-}
-
-static void update_symref_reflog(struct files_ref_store *refs,
-				 struct ref_lock *lock, const char *refname,
-				 const char *target, const char *logmsg)
-{
-	struct strbuf err = STRBUF_INIT;
-	struct object_id new_oid;
-	if (logmsg &&
-	    !refs_read_ref_full(&refs->base, target,
-				RESOLVE_REF_READING, &new_oid, NULL) &&
-	    files_log_ref_write(refs, refname, &lock->old_oid,
-				&new_oid, logmsg, 0, &err)) {
-		error("%s", err.buf);
-		strbuf_release(&err);
-	}
-}
-
-static int create_symref_locked(struct files_ref_store *refs,
-				struct ref_lock *lock, const char *refname,
-				const char *target, const char *logmsg)
-{
-	if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
-		update_symref_reflog(refs, lock, refname, target, logmsg);
-		return 0;
-	}
-
-	if (!fdopen_lock_file(&lock->lk, "w"))
-		return error("unable to fdopen %s: %s",
-			     lock->lk.tempfile->filename.buf, strerror(errno));
-
-	update_symref_reflog(refs, lock, refname, target, logmsg);
-
-	/* no error check; commit_ref will check ferror */
-	fprintf(lock->lk.tempfile->fp, "ref: %s\n", target);
-	if (commit_ref(lock) < 0)
-		return error("unable to write symref for %s: %s", refname,
-			     strerror(errno));
-	return 0;
-}
-
-static int files_create_symref(struct ref_store *ref_store,
-			       const char *refname, const char *target,
-			       const char *logmsg)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
-	struct strbuf err = STRBUF_INIT;
-	struct ref_lock *lock;
-	int ret;
-
-	lock = lock_ref_oid_basic(refs, refname, NULL,
-				  NULL, NULL, REF_NO_DEREF, NULL,
-				  &err);
-	if (!lock) {
-		error("%s", err.buf);
-		strbuf_release(&err);
-		return -1;
-	}
-
-	ret = create_symref_locked(refs, lock, refname, target, logmsg);
-	unlock_ref(lock);
-	return ret;
-}
-
-static int files_reflog_exists(struct ref_store *ref_store,
-			       const char *refname)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
-	struct strbuf sb = STRBUF_INIT;
-	struct stat st;
-	int ret;
-
-	files_reflog_path(refs, &sb, refname);
-	ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int files_delete_reflog(struct ref_store *ref_store,
-			       const char *refname)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
-	struct strbuf sb = STRBUF_INIT;
-	int ret;
-
-	files_reflog_path(refs, &sb, refname);
-	ret = remove_path(sb.buf);
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
-{
-	struct object_id ooid, noid;
-	char *email_end, *message;
-	timestamp_t timestamp;
-	int tz;
-	const char *p = sb->buf;
-
-	/* old SP new SP name <email> SP time TAB msg LF */
-	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 = parse_timestamp(email_end + 2, &message, 10)) ||
-	    !message || message[0] != ' ' ||
-	    (message[1] != '+' && message[1] != '-') ||
-	    !isdigit(message[2]) || !isdigit(message[3]) ||
-	    !isdigit(message[4]) || !isdigit(message[5]))
-		return 0; /* corrupt? */
-	email_end[1] = '\0';
-	tz = strtol(message + 1, NULL, 10);
-	if (message[6] != '\t')
-		message += 6;
-	else
-		message += 7;
-	return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
-}
-
-static char *find_beginning_of_line(char *bob, char *scan)
-{
-	while (bob < scan && *(--scan) != '\n')
-		; /* keep scanning backwards */
-	/*
-	 * Return either beginning of the buffer, or LF at the end of
-	 * the previous line.
-	 */
-	return scan;
-}
-
-static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
-					     const char *refname,
-					     each_reflog_ent_fn fn,
-					     void *cb_data)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ,
-			       "for_each_reflog_ent_reverse");
-	struct strbuf sb = STRBUF_INIT;
-	FILE *logfp;
-	long pos;
-	int ret = 0, at_tail = 1;
-
-	files_reflog_path(refs, &sb, refname);
-	logfp = fopen(sb.buf, "r");
-	strbuf_release(&sb);
-	if (!logfp)
-		return -1;
-
-	/* Jump to the end */
-	if (fseek(logfp, 0, SEEK_END) < 0)
-		ret = error("cannot seek back reflog for %s: %s",
-			    refname, strerror(errno));
-	pos = ftell(logfp);
-	while (!ret && 0 < pos) {
-		int cnt;
-		size_t nread;
-		char buf[BUFSIZ];
-		char *endp, *scanp;
-
-		/* Fill next block from the end */
-		cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
-		if (fseek(logfp, pos - cnt, SEEK_SET)) {
-			ret = error("cannot seek back reflog for %s: %s",
-				    refname, strerror(errno));
-			break;
-		}
-		nread = fread(buf, cnt, 1, logfp);
-		if (nread != 1) {
-			ret = error("cannot read %d bytes from reflog for %s: %s",
-				    cnt, refname, strerror(errno));
-			break;
-		}
-		pos -= cnt;
-
-		scanp = endp = buf + cnt;
-		if (at_tail && scanp[-1] == '\n')
-			/* Looking at the final LF at the end of the file */
-			scanp--;
-		at_tail = 0;
-
-		while (buf < scanp) {
-			/*
-			 * terminating LF of the previous line, or the beginning
-			 * of the buffer.
-			 */
-			char *bp;
-
-			bp = find_beginning_of_line(buf, scanp);
-
-			if (*bp == '\n') {
-				/*
-				 * The newline is the end of the previous line,
-				 * so we know we have complete line starting
-				 * at (bp + 1). Prefix it onto any prior data
-				 * we collected for the line and process it.
-				 */
-				strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
-				scanp = bp;
-				endp = bp + 1;
-				ret = show_one_reflog_ent(&sb, fn, cb_data);
-				strbuf_reset(&sb);
-				if (ret)
-					break;
-			} else if (!pos) {
-				/*
-				 * We are at the start of the buffer, and the
-				 * start of the file; there is no previous
-				 * line, and we have everything for this one.
-				 * Process it, and we can end the loop.
-				 */
-				strbuf_splice(&sb, 0, 0, buf, endp - buf);
-				ret = show_one_reflog_ent(&sb, fn, cb_data);
-				strbuf_reset(&sb);
-				break;
-			}
-
-			if (bp == buf) {
-				/*
-				 * We are at the start of the buffer, and there
-				 * is more file to read backwards. Which means
-				 * we are in the middle of a line. Note that we
-				 * may get here even if *bp was a newline; that
-				 * just means we are at the exact end of the
-				 * previous line, rather than some spot in the
-				 * middle.
-				 *
-				 * Save away what we have to be combined with
-				 * the data from the next read.
-				 */
-				strbuf_splice(&sb, 0, 0, buf, endp - buf);
-				break;
-			}
-		}
-
-	}
-	if (!ret && sb.len)
-		BUG("reverse reflog parser had leftover data");
-
-	fclose(logfp);
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int files_for_each_reflog_ent(struct ref_store *ref_store,
-				     const char *refname,
-				     each_reflog_ent_fn fn, void *cb_data)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ,
-			       "for_each_reflog_ent");
-	FILE *logfp;
-	struct strbuf sb = STRBUF_INIT;
-	int ret = 0;
-
-	files_reflog_path(refs, &sb, refname);
-	logfp = fopen(sb.buf, "r");
-	strbuf_release(&sb);
-	if (!logfp)
-		return -1;
-
-	while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
-		ret = show_one_reflog_ent(&sb, fn, cb_data);
-	fclose(logfp);
-	strbuf_release(&sb);
-	return ret;
-}
-
-struct files_reflog_iterator {
-	struct ref_iterator base;
-
-	struct ref_store *ref_store;
-	struct dir_iterator *dir_iterator;
-	struct object_id oid;
-};
-
-static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
-{
-	struct files_reflog_iterator *iter =
-		(struct files_reflog_iterator *)ref_iterator;
-	struct dir_iterator *diter = iter->dir_iterator;
-	int ok;
-
-	while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
-		int flags;
-
-		if (!S_ISREG(diter->st.st_mode))
-			continue;
-		if (diter->basename[0] == '.')
-			continue;
-		if (ends_with(diter->basename, ".lock"))
-			continue;
-
-		if (refs_read_ref_full(iter->ref_store,
-				       diter->relative_path, 0,
-				       &iter->oid, &flags)) {
-			error("bad ref for %s", diter->path.buf);
-			continue;
-		}
-
-		iter->base.refname = diter->relative_path;
-		iter->base.oid = &iter->oid;
-		iter->base.flags = flags;
-		return ITER_OK;
-	}
-
-	iter->dir_iterator = NULL;
-	if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
-		ok = ITER_ERROR;
-	return ok;
-}
-
-static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
-				   struct object_id *peeled)
-{
-	BUG("ref_iterator_peel() called for reflog_iterator");
-}
-
-static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
-{
-	struct files_reflog_iterator *iter =
-		(struct files_reflog_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->dir_iterator)
-		ok = dir_iterator_abort(iter->dir_iterator);
-
-	base_ref_iterator_free(ref_iterator);
-	return ok;
-}
-
-static struct ref_iterator_vtable files_reflog_iterator_vtable = {
-	files_reflog_iterator_advance,
-	files_reflog_iterator_peel,
-	files_reflog_iterator_abort
-};
-
-static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
-						  const char *gitdir)
-{
-	struct dir_iterator *diter;
-	struct files_reflog_iterator *iter;
-	struct ref_iterator *ref_iterator;
-	struct strbuf sb = STRBUF_INIT;
-
-	strbuf_addf(&sb, "%s/logs", gitdir);
-
-	diter = dir_iterator_begin(sb.buf, 0);
-	if (!diter) {
-		strbuf_release(&sb);
-		return empty_ref_iterator_begin();
-	}
-
-	iter = xcalloc(1, sizeof(*iter));
-	ref_iterator = &iter->base;
-
-	base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
-	iter->dir_iterator = diter;
-	iter->ref_store = ref_store;
-	strbuf_release(&sb);
-
-	return ref_iterator;
-}
-
-static enum iterator_selection reflog_iterator_select(
-	struct ref_iterator *iter_worktree,
-	struct ref_iterator *iter_common,
-	void *cb_data)
-{
-	if (iter_worktree) {
-		/*
-		 * We're a bit loose here. We probably should ignore
-		 * common refs if they are accidentally added as
-		 * per-worktree refs.
-		 */
-		return ITER_SELECT_0;
-	} else if (iter_common) {
-		if (ref_type(iter_common->refname) == REF_TYPE_NORMAL)
-			return ITER_SELECT_1;
-
-		/*
-		 * The main ref store may contain main worktree's
-		 * per-worktree refs, which should be ignored
-		 */
-		return ITER_SKIP_1;
-	} else
-		return ITER_DONE;
-}
-
-static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ,
-			       "reflog_iterator_begin");
-
-	if (!strcmp(refs->base.gitdir, refs->gitcommondir)) {
-		return reflog_iterator_begin(ref_store, refs->gitcommondir);
-	} else {
-		return merge_ref_iterator_begin(
-			0, reflog_iterator_begin(ref_store, refs->base.gitdir),
-			reflog_iterator_begin(ref_store, refs->gitcommondir),
-			reflog_iterator_select, refs);
-	}
-}
-
-/*
- * If update is a direct update of head_ref (the reference pointed to
- * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
- */
-static int split_head_update(struct ref_update *update,
-			     struct ref_transaction *transaction,
-			     const char *head_ref,
-			     struct string_list *affected_refnames,
-			     struct strbuf *err)
-{
-	struct string_list_item *item;
-	struct ref_update *new_update;
-
-	if ((update->flags & REF_LOG_ONLY) ||
-	    (update->flags & REF_IS_PRUNING) ||
-	    (update->flags & REF_UPDATE_VIA_HEAD))
-		return 0;
-
-	if (strcmp(update->refname, head_ref))
-		return 0;
-
-	/*
-	 * First make sure that HEAD is not already in the
-	 * transaction. This check is O(lg N) in the transaction
-	 * size, but it happens at most once per transaction.
-	 */
-	if (string_list_has_string(affected_refnames, "HEAD")) {
-		/* An entry already existed */
-		strbuf_addf(err,
-			    "multiple updates for 'HEAD' (including one "
-			    "via its referent '%s') are not allowed",
-			    update->refname);
-		return TRANSACTION_NAME_CONFLICT;
-	}
-
-	new_update = ref_transaction_add_update(
-			transaction, "HEAD",
-			update->flags | REF_LOG_ONLY | REF_NO_DEREF,
-			&update->new_oid, &update->old_oid,
-			update->msg);
-
-	/*
-	 * Add "HEAD". This insertion is O(N) in the transaction
-	 * size, but it happens at most once per transaction.
-	 * Add new_update->refname instead of a literal "HEAD".
-	 */
-	if (strcmp(new_update->refname, "HEAD"))
-		BUG("%s unexpectedly not 'HEAD'", new_update->refname);
-	item = string_list_insert(affected_refnames, new_update->refname);
-	item->util = new_update;
-
-	return 0;
-}
-
-/*
- * update is for a symref that points at referent and doesn't have
- * REF_NO_DEREF set. Split it into two updates:
- * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set
- * - A new, separate update for the referent reference
- * Note that the new update will itself be subject to splitting when
- * the iteration gets to it.
- */
-static int split_symref_update(struct ref_update *update,
-			       const char *referent,
-			       struct ref_transaction *transaction,
-			       struct string_list *affected_refnames,
-			       struct strbuf *err)
-{
-	struct string_list_item *item;
-	struct ref_update *new_update;
-	unsigned int new_flags;
-
-	/*
-	 * First make sure that referent is not already in the
-	 * transaction. This check is O(lg N) in the transaction
-	 * size, but it happens at most once per symref in a
-	 * transaction.
-	 */
-	if (string_list_has_string(affected_refnames, referent)) {
-		/* An entry already exists */
-		strbuf_addf(err,
-			    "multiple updates for '%s' (including one "
-			    "via symref '%s') are not allowed",
-			    referent, update->refname);
-		return TRANSACTION_NAME_CONFLICT;
-	}
-
-	new_flags = update->flags;
-	if (!strcmp(update->refname, "HEAD")) {
-		/*
-		 * Record that the new update came via HEAD, so that
-		 * when we process it, split_head_update() doesn't try
-		 * to add another reflog update for HEAD. Note that
-		 * this bit will be propagated if the new_update
-		 * itself needs to be split.
-		 */
-		new_flags |= REF_UPDATE_VIA_HEAD;
-	}
-
-	new_update = ref_transaction_add_update(
-			transaction, referent, new_flags,
-			&update->new_oid, &update->old_oid,
-			update->msg);
-
-	new_update->parent_update = update;
-
-	/*
-	 * Change the symbolic ref update to log only. Also, it
-	 * doesn't need to check its old OID value, as that will be
-	 * done when new_update is processed.
-	 */
-	update->flags |= REF_LOG_ONLY | REF_NO_DEREF;
-	update->flags &= ~REF_HAVE_OLD;
-
-	/*
-	 * Add the referent. This insertion is O(N) in the transaction
-	 * size, but it happens at most once per symref in a
-	 * transaction. Make sure to add new_update->refname, which will
-	 * be valid as long as affected_refnames is in use, and NOT
-	 * referent, which might soon be freed by our caller.
-	 */
-	item = string_list_insert(affected_refnames, new_update->refname);
-	if (item->util)
-		BUG("%s unexpectedly found in affected_refnames",
-		    new_update->refname);
-	item->util = new_update;
-
-	return 0;
-}
-
-/*
- * Return the refname under which update was originally requested.
- */
-static const char *original_update_refname(struct ref_update *update)
-{
-	while (update->parent_update)
-		update = update->parent_update;
-
-	return update->refname;
-}
-
-/*
- * Check whether the REF_HAVE_OLD and old_oid values stored in update
- * are consistent with oid, which is the reference's current value. If
- * everything is OK, return 0; otherwise, write an error message to
- * err and return -1.
- */
-static int check_old_oid(struct ref_update *update, struct object_id *oid,
-			 struct strbuf *err)
-{
-	if (!(update->flags & REF_HAVE_OLD) ||
-		   oideq(oid, &update->old_oid))
-		return 0;
-
-	if (is_null_oid(&update->old_oid))
-		strbuf_addf(err, "cannot lock ref '%s': "
-			    "reference already exists",
-			    original_update_refname(update));
-	else if (is_null_oid(oid))
-		strbuf_addf(err, "cannot lock ref '%s': "
-			    "reference is missing but expected %s",
-			    original_update_refname(update),
-			    oid_to_hex(&update->old_oid));
-	else
-		strbuf_addf(err, "cannot lock ref '%s': "
-			    "is at %s but expected %s",
-			    original_update_refname(update),
-			    oid_to_hex(oid),
-			    oid_to_hex(&update->old_oid));
-
-	return -1;
-}
-
-/*
- * Prepare for carrying out update:
- * - Lock the reference referred to by update.
- * - Read the reference under lock.
- * - Check that its old OID value (if specified) is correct, and in
- *   any case record it in update->lock->old_oid for later use when
- *   writing the reflog.
- * - If it is a symref update without REF_NO_DEREF, split it up into a
- *   REF_LOG_ONLY update of the symref and add a separate update for
- *   the referent to transaction.
- * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
- *   update of HEAD.
- */
-static int lock_ref_for_update(struct files_ref_store *refs,
-			       struct ref_update *update,
-			       struct ref_transaction *transaction,
-			       const char *head_ref,
-			       struct string_list *affected_refnames,
-			       struct strbuf *err)
-{
-	struct strbuf referent = STRBUF_INIT;
-	int mustexist = (update->flags & REF_HAVE_OLD) &&
-		!is_null_oid(&update->old_oid);
-	int ret = 0;
-	struct ref_lock *lock;
-
-	files_assert_main_repository(refs, "lock_ref_for_update");
-
-	if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
-		update->flags |= REF_DELETING;
-
-	if (head_ref) {
-		ret = split_head_update(update, transaction, head_ref,
-					affected_refnames, err);
-		if (ret)
-			goto out;
-	}
-
-	ret = lock_raw_ref(refs, update->refname, mustexist,
-			   affected_refnames, NULL,
-			   &lock, &referent,
-			   &update->type, err);
-	if (ret) {
-		char *reason;
-
-		reason = strbuf_detach(err, NULL);
-		strbuf_addf(err, "cannot lock ref '%s': %s",
-			    original_update_refname(update), reason);
-		free(reason);
-		goto out;
-	}
-
-	update->backend_data = lock;
-
-	if (update->type & REF_ISSYMREF) {
-		if (update->flags & REF_NO_DEREF) {
-			/*
-			 * We won't be reading the referent as part of
-			 * the transaction, so we have to read it here
-			 * to record and possibly check old_oid:
-			 */
-			if (refs_read_ref_full(&refs->base,
-					       referent.buf, 0,
-					       &lock->old_oid, NULL)) {
-				if (update->flags & REF_HAVE_OLD) {
-					strbuf_addf(err, "cannot lock ref '%s': "
-						    "error reading reference",
-						    original_update_refname(update));
-					ret = TRANSACTION_GENERIC_ERROR;
-					goto out;
-				}
-			} else if (check_old_oid(update, &lock->old_oid, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto out;
-			}
-		} else {
-			/*
-			 * Create a new update for the reference this
-			 * symref is pointing at. Also, we will record
-			 * and verify old_oid for this update as part
-			 * of processing the split-off update, so we
-			 * don't have to do it here.
-			 */
-			ret = split_symref_update(update,
-						  referent.buf, transaction,
-						  affected_refnames, err);
-			if (ret)
-				goto out;
-		}
-	} else {
-		struct ref_update *parent_update;
-
-		if (check_old_oid(update, &lock->old_oid, err)) {
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto out;
-		}
-
-		/*
-		 * If this update is happening indirectly because of a
-		 * symref update, record the old OID in the parent
-		 * update:
-		 */
-		for (parent_update = update->parent_update;
-		     parent_update;
-		     parent_update = parent_update->parent_update) {
-			struct ref_lock *parent_lock = parent_update->backend_data;
-			oidcpy(&parent_lock->old_oid, &lock->old_oid);
-		}
-	}
-
-	if ((update->flags & REF_HAVE_NEW) &&
-	    !(update->flags & REF_DELETING) &&
-	    !(update->flags & REF_LOG_ONLY)) {
-		if (!(update->type & REF_ISSYMREF) &&
-		    oideq(&lock->old_oid, &update->new_oid)) {
-			/*
-			 * The reference already has the desired
-			 * value, so we don't need to write it.
-			 */
-		} else if (write_ref_to_lockfile(lock, &update->new_oid,
-						 err)) {
-			char *write_err = strbuf_detach(err, NULL);
-
-			/*
-			 * The lock was freed upon failure of
-			 * write_ref_to_lockfile():
-			 */
-			update->backend_data = NULL;
-			strbuf_addf(err,
-				    "cannot update ref '%s': %s",
-				    update->refname, write_err);
-			free(write_err);
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto out;
-		} else {
-			update->flags |= REF_NEEDS_COMMIT;
-		}
-	}
-	if (!(update->flags & REF_NEEDS_COMMIT)) {
-		/*
-		 * We didn't call write_ref_to_lockfile(), so
-		 * the lockfile is still open. Close it to
-		 * free up the file descriptor:
-		 */
-		if (close_ref_gently(lock)) {
-			strbuf_addf(err, "couldn't close '%s.lock'",
-				    update->refname);
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto out;
-		}
-	}
-
-out:
-	strbuf_release(&referent);
-	return ret;
-}
-
-struct files_transaction_backend_data {
-	struct ref_transaction *packed_transaction;
-	int packed_refs_locked;
-};
-
-/*
- * Unlock any references in `transaction` that are still locked, and
- * mark the transaction closed.
- */
-static void files_transaction_cleanup(struct files_ref_store *refs,
-				      struct ref_transaction *transaction)
-{
-	size_t i;
-	struct files_transaction_backend_data *backend_data =
-		transaction->backend_data;
-	struct strbuf err = STRBUF_INIT;
-
-	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);
-			update->backend_data = NULL;
-		}
-	}
-
-	if (backend_data) {
-		if (backend_data->packed_transaction &&
-		    ref_transaction_abort(backend_data->packed_transaction, &err)) {
-			error("error aborting transaction: %s", err.buf);
-			strbuf_release(&err);
-		}
-
-		if (backend_data->packed_refs_locked)
-			packed_refs_unlock(refs->packed_ref_store);
-
-		free(backend_data);
-	}
-
-	transaction->state = REF_TRANSACTION_CLOSED;
-}
-
-static int files_transaction_prepare(struct ref_store *ref_store,
-				     struct ref_transaction *transaction,
-				     struct strbuf *err)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE,
-			       "ref_transaction_prepare");
-	size_t i;
-	int ret = 0;
-	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-	char *head_ref = NULL;
-	int head_type;
-	struct files_transaction_backend_data *backend_data;
-	struct ref_transaction *packed_transaction = NULL;
-
-	assert(err);
-
-	if (!transaction->nr)
-		goto cleanup;
-
-	backend_data = xcalloc(1, sizeof(*backend_data));
-	transaction->backend_data = backend_data;
-
-	/*
-	 * Fail if a refname appears more than once in the
-	 * transaction. (If we end up splitting up any updates using
-	 * split_symref_update() or split_head_update(), those
-	 * functions will check that the new updates don't have the
-	 * same refname as any existing ones.) Also fail if any of the
-	 * updates use REF_IS_PRUNING without REF_NO_DEREF.
-	 */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-		struct string_list_item *item =
-			string_list_append(&affected_refnames, update->refname);
-
-		if ((update->flags & REF_IS_PRUNING) &&
-		    !(update->flags & REF_NO_DEREF))
-			BUG("REF_IS_PRUNING set without REF_NO_DEREF");
-
-		/*
-		 * We store a pointer to update in item->util, but at
-		 * the moment we never use the value of this field
-		 * except to check whether it is non-NULL.
-		 */
-		item->util = update;
-	}
-	string_list_sort(&affected_refnames);
-	if (ref_update_reject_duplicates(&affected_refnames, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	/*
-	 * Special hack: If a branch is updated directly and HEAD
-	 * points to it (may happen on the remote side of a push
-	 * for example) then logically the HEAD reflog should be
-	 * updated too.
-	 *
-	 * A generic solution would require reverse symref lookups,
-	 * but finding all symrefs pointing to a given branch would be
-	 * rather costly for this rare event (the direct update of a
-	 * branch) to be worth it. So let's cheat and check with HEAD
-	 * only, which should cover 99% of all usage scenarios (even
-	 * 100% of the default ones).
-	 *
-	 * So if HEAD is a symbolic reference, then record the name of
-	 * the reference that it points to. If we see an update of
-	 * head_ref within the transaction, then split_head_update()
-	 * arranges for the reflog of HEAD to be updated, too.
-	 */
-	head_ref = refs_resolve_refdup(ref_store, "HEAD",
-				       RESOLVE_REF_NO_RECURSE,
-				       NULL, &head_type);
-
-	if (head_ref && !(head_type & REF_ISSYMREF)) {
-		FREE_AND_NULL(head_ref);
-	}
-
-	/*
-	 * 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.
-	 * Note that lock_ref_for_update() might append more updates
-	 * to the transaction.
-	 */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-
-		ret = lock_ref_for_update(refs, update, transaction,
-					  head_ref, &affected_refnames, err);
-		if (ret)
-			goto cleanup;
-
-		if (update->flags & REF_DELETING &&
-		    !(update->flags & REF_LOG_ONLY) &&
-		    !(update->flags & REF_IS_PRUNING)) {
-			/*
-			 * This reference has to be deleted from
-			 * packed-refs if it exists there.
-			 */
-			if (!packed_transaction) {
-				packed_transaction = ref_store_transaction_begin(
-						refs->packed_ref_store, err);
-				if (!packed_transaction) {
-					ret = TRANSACTION_GENERIC_ERROR;
-					goto cleanup;
-				}
-
-				backend_data->packed_transaction =
-					packed_transaction;
-			}
-
-			ref_transaction_add_update(
-					packed_transaction, update->refname,
-					REF_HAVE_NEW | REF_NO_DEREF,
-					&update->new_oid, NULL,
-					NULL);
-		}
-	}
-
-	if (packed_transaction) {
-		if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto cleanup;
-		}
-		backend_data->packed_refs_locked = 1;
-
-		if (is_packed_transaction_needed(refs->packed_ref_store,
-						 packed_transaction)) {
-			ret = ref_transaction_prepare(packed_transaction, err);
-			/*
-			 * A failure during the prepare step will abort
-			 * itself, but not free. Do that now, and disconnect
-			 * from the files_transaction so it does not try to
-			 * abort us when we hit the cleanup code below.
-			 */
-			if (ret) {
-				ref_transaction_free(packed_transaction);
-				backend_data->packed_transaction = NULL;
-			}
-		} else {
-			/*
-			 * We can skip rewriting the `packed-refs`
-			 * file. But we do need to leave it locked, so
-			 * that somebody else doesn't pack a reference
-			 * that we are trying to delete.
-			 *
-			 * We need to disconnect our transaction from
-			 * backend_data, since the abort (whether successful or
-			 * not) will free it.
-			 */
-			backend_data->packed_transaction = NULL;
-			if (ref_transaction_abort(packed_transaction, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			}
-		}
-	}
-
-cleanup:
-	free(head_ref);
-	string_list_clear(&affected_refnames, 0);
-
-	if (ret)
-		files_transaction_cleanup(refs, transaction);
-	else
-		transaction->state = REF_TRANSACTION_PREPARED;
-
-	return ret;
-}
-
-static int files_transaction_finish(struct ref_store *ref_store,
-				    struct ref_transaction *transaction,
-				    struct strbuf *err)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, 0, "ref_transaction_finish");
-	size_t i;
-	int ret = 0;
-	struct strbuf sb = STRBUF_INIT;
-	struct files_transaction_backend_data *backend_data;
-	struct ref_transaction *packed_transaction;
-
-
-	assert(err);
-
-	if (!transaction->nr) {
-		transaction->state = REF_TRANSACTION_CLOSED;
-		return 0;
-	}
-
-	backend_data = transaction->backend_data;
-	packed_transaction = backend_data->packed_transaction;
-
-	/* Perform updates first so live commits remain referenced */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-		struct ref_lock *lock = update->backend_data;
-
-		if (update->flags & REF_NEEDS_COMMIT ||
-		    update->flags & REF_LOG_ONLY) {
-			if (files_log_ref_write(refs,
-						lock->ref_name,
-						&lock->old_oid,
-						&update->new_oid,
-						update->msg, update->flags,
-						err)) {
-				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);
-				update->backend_data = NULL;
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			}
-		}
-		if (update->flags & REF_NEEDS_COMMIT) {
-			clear_loose_ref_cache(refs);
-			if (commit_ref(lock)) {
-				strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
-				unlock_ref(lock);
-				update->backend_data = NULL;
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			}
-		}
-	}
-
-	/*
-	 * Now that updates are safely completed, we can perform
-	 * deletes. First delete the reflogs of any references that
-	 * will be deleted, since (in the unexpected event of an
-	 * error) leaving a reference without a reflog is less bad
-	 * than leaving a reflog without a reference (the latter is a
-	 * mildly invalid repository state):
-	 */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-		if (update->flags & REF_DELETING &&
-		    !(update->flags & REF_LOG_ONLY) &&
-		    !(update->flags & REF_IS_PRUNING)) {
-			strbuf_reset(&sb);
-			files_reflog_path(refs, &sb, update->refname);
-			if (!unlink_or_warn(sb.buf))
-				try_remove_empty_parents(refs, update->refname,
-							 REMOVE_EMPTY_PARENTS_REFLOG);
-		}
-	}
-
-	/*
-	 * Perform deletes now that updates are safely completed.
-	 *
-	 * First delete any packed versions of the references, while
-	 * retaining the packed-refs lock:
-	 */
-	if (packed_transaction) {
-		ret = ref_transaction_commit(packed_transaction, err);
-		ref_transaction_free(packed_transaction);
-		packed_transaction = NULL;
-		backend_data->packed_transaction = NULL;
-		if (ret)
-			goto cleanup;
-	}
-
-	/* Now delete the loose versions of the references: */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-		struct ref_lock *lock = update->backend_data;
-
-		if (update->flags & REF_DELETING &&
-		    !(update->flags & REF_LOG_ONLY)) {
-			if (!(update->type & REF_ISPACKED) ||
-			    update->type & REF_ISSYMREF) {
-				/* It is a loose reference. */
-				strbuf_reset(&sb);
-				files_ref_path(refs, &sb, lock->ref_name);
-				if (unlink_or_msg(sb.buf, err)) {
-					ret = TRANSACTION_GENERIC_ERROR;
-					goto cleanup;
-				}
-				update->flags |= REF_DELETED_LOOSE;
-			}
-		}
-	}
-
-	clear_loose_ref_cache(refs);
-
-cleanup:
-	files_transaction_cleanup(refs, transaction);
-
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-
-		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(refs, update->refname,
-						 REMOVE_EMPTY_PARENTS_REF);
-		}
-	}
-
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int files_transaction_abort(struct ref_store *ref_store,
-				   struct ref_transaction *transaction,
-				   struct strbuf *err)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, 0, "ref_transaction_abort");
-
-	files_transaction_cleanup(refs, transaction);
-	return 0;
-}
-
-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);
-}
-
-static int files_initial_transaction_commit(struct ref_store *ref_store,
-					    struct ref_transaction *transaction,
-					    struct strbuf *err)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE,
-			       "initial_ref_transaction_commit");
-	size_t i;
-	int ret = 0;
-	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-	struct ref_transaction *packed_transaction = NULL;
-
-	assert(err);
-
-	if (transaction->state != REF_TRANSACTION_OPEN)
-		BUG("commit called for transaction that is not open");
-
-	/* Fail if a refname appears more than once in the transaction: */
-	for (i = 0; i < transaction->nr; i++)
-		string_list_append(&affected_refnames,
-				   transaction->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 (refs_for_each_rawref(&refs->base, ref_present,
-				 &affected_refnames))
-		BUG("initial ref transaction called with existing refs");
-
-	packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
-	if (!packed_transaction) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-
-		if ((update->flags & REF_HAVE_OLD) &&
-		    !is_null_oid(&update->old_oid))
-			BUG("initial ref transaction with old_sha1 set");
-		if (refs_verify_refname_available(&refs->base, update->refname,
-						  &affected_refnames, NULL,
-						  err)) {
-			ret = TRANSACTION_NAME_CONFLICT;
-			goto cleanup;
-		}
-
-		/*
-		 * Add a reference creation for this reference to the
-		 * packed-refs transaction:
-		 */
-		ref_transaction_add_update(packed_transaction, update->refname,
-					   update->flags & ~REF_HAVE_OLD,
-					   &update->new_oid, &update->old_oid,
-					   NULL);
-	}
-
-	if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	if (initial_ref_transaction_commit(packed_transaction, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-	}
-
-	packed_refs_unlock(refs->packed_ref_store);
-cleanup:
-	if (packed_transaction)
-		ref_transaction_free(packed_transaction);
-	transaction->state = REF_TRANSACTION_CLOSED;
-	string_list_clear(&affected_refnames, 0);
-	return ret;
-}
-
-struct expire_reflog_cb {
-	unsigned int flags;
-	reflog_expiry_should_prune_fn *should_prune_fn;
-	void *policy_cb;
-	FILE *newlog;
-	struct object_id last_kept_oid;
-};
-
-static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
-			     const char *email, timestamp_t timestamp, int tz,
-			     const char *message, void *cb_data)
-{
-	struct expire_reflog_cb *cb = cb_data;
-	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
-
-	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
-		ooid = &cb->last_kept_oid;
-
-	if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
-				   message, policy_cb)) {
-		if (!cb->newlog)
-			printf("would prune %s", message);
-		else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("prune %s", message);
-	} else {
-		if (cb->newlog) {
-			fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
-				oid_to_hex(ooid), oid_to_hex(noid),
-				email, timestamp, tz, message);
-			oidcpy(&cb->last_kept_oid, noid);
-		}
-		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("keep %s", message);
-	}
-	return 0;
-}
-
-static int files_reflog_expire(struct ref_store *ref_store,
-			       const char *refname, const struct object_id *oid,
-			       unsigned int flags,
-			       reflog_expiry_prepare_fn prepare_fn,
-			       reflog_expiry_should_prune_fn should_prune_fn,
-			       reflog_expiry_cleanup_fn cleanup_fn,
-			       void *policy_cb_data)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
-	struct lock_file reflog_lock = LOCK_INIT;
-	struct expire_reflog_cb cb;
-	struct ref_lock *lock;
-	struct strbuf log_file_sb = STRBUF_INIT;
-	char *log_file;
-	int status = 0;
-	int type;
-	struct strbuf err = STRBUF_INIT;
-
-	memset(&cb, 0, sizeof(cb));
-	cb.flags = flags;
-	cb.policy_cb = policy_cb_data;
-	cb.should_prune_fn = should_prune_fn;
-
-	/*
-	 * The reflog file is locked by holding the lock on the
-	 * reference itself, plus we might need to update the
-	 * reference if --updateref was specified:
-	 */
-	lock = lock_ref_oid_basic(refs, refname, oid,
-				  NULL, NULL, REF_NO_DEREF,
-				  &type, &err);
-	if (!lock) {
-		error("cannot lock ref '%s': %s", refname, err.buf);
-		strbuf_release(&err);
-		return -1;
-	}
-	if (!refs_reflog_exists(ref_store, refname)) {
-		unlock_ref(lock);
-		return 0;
-	}
-
-	files_reflog_path(refs, &log_file_sb, refname);
-	log_file = strbuf_detach(&log_file_sb, NULL);
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-		/*
-		 * Even though holding $GIT_DIR/logs/$reflog.lock has
-		 * no locking implications, we use the lock_file
-		 * machinery here anyway because it does a lot of the
-		 * work we need, including cleaning up if the program
-		 * exits unexpectedly.
-		 */
-		if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
-			struct strbuf err = STRBUF_INIT;
-			unable_to_lock_message(log_file, errno, &err);
-			error("%s", err.buf);
-			strbuf_release(&err);
-			goto failure;
-		}
-		cb.newlog = fdopen_lock_file(&reflog_lock, "w");
-		if (!cb.newlog) {
-			error("cannot fdopen %s (%s)",
-			      get_lock_file_path(&reflog_lock), strerror(errno));
-			goto failure;
-		}
-	}
-
-	(*prepare_fn)(refname, oid, cb.policy_cb);
-	refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
-	(*cleanup_fn)(cb.policy_cb);
-
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-		/*
-		 * It doesn't make sense to adjust a reference pointed
-		 * to by a symbolic ref based on expiring entries in
-		 * the symbolic reference's reflog. Nor can we update
-		 * a reference if there are no remaining reflog
-		 * entries.
-		 */
-		int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
-			!(type & REF_ISSYMREF) &&
-			!is_null_oid(&cb.last_kept_oid);
-
-		if (close_lock_file_gently(&reflog_lock)) {
-			status |= error("couldn't write %s: %s", log_file,
-					strerror(errno));
-			rollback_lock_file(&reflog_lock);
-		} else if (update &&
-			   (write_in_full(get_lock_file_fd(&lock->lk),
-				oid_to_hex(&cb.last_kept_oid), the_hash_algo->hexsz) < 0 ||
-			    write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
-			    close_ref_gently(lock) < 0)) {
-			status |= error("couldn't write %s",
-					get_lock_file_path(&lock->lk));
-			rollback_lock_file(&reflog_lock);
-		} else if (commit_lock_file(&reflog_lock)) {
-			status |= error("unable to write reflog '%s' (%s)",
-					log_file, strerror(errno));
-		} else if (update && commit_ref(lock)) {
-			status |= error("couldn't set %s", lock->ref_name);
-		}
-	}
-	free(log_file);
-	unlock_ref(lock);
-	return status;
-
- failure:
-	rollback_lock_file(&reflog_lock);
-	free(log_file);
-	unlock_ref(lock);
-	return -1;
-}
-
-static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "init_db");
-	struct strbuf sb = STRBUF_INIT;
-
-	/*
-	 * Create .git/refs/{heads,tags}
-	 */
-	files_ref_path(refs, &sb, "refs/heads");
-	safe_create_dir(sb.buf, 1);
-
-	strbuf_reset(&sb);
-	files_ref_path(refs, &sb, "refs/tags");
-	safe_create_dir(sb.buf, 1);
-
-	strbuf_release(&sb);
-	return 0;
-}
-
-struct ref_storage_be refs_be_files = {
-	NULL,
-	"files",
-	files_ref_store_create,
-	files_init_db,
-	files_transaction_prepare,
-	files_transaction_finish,
-	files_transaction_abort,
-	files_initial_transaction_commit,
-
-	files_pack_refs,
-	files_create_symref,
-	files_delete_refs,
-	files_rename_ref,
-	files_copy_ref,
-
-	files_ref_iterator_begin,
-	files_read_raw_ref,
-
-	files_reflog_iterator_begin,
-	files_for_each_reflog_ent,
-	files_for_each_reflog_ent_reverse,
-	files_reflog_exists,
-	files_create_reflog,
-	files_delete_reflog,
-	files_reflog_expire
-};