Adding upstream version 1:2.43.0.upstream/1%2.43.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2649 insertions, 0 deletions

diff --git a/refs.c b/refs.c
new file mode 100644
index 0000000..fcae5dd
--- /dev/null
+++ b/refs.c
@@ -0,0 +1,2649 @@
+/*
+ * The backend-independent part of the reference module.
+ */
+
+#include "git-compat-util.h"
+#include "advice.h"
+#include "config.h"
+#include "environment.h"
+#include "hashmap.h"
+#include "gettext.h"
+#include "hex.h"
+#include "lockfile.h"
+#include "iterator.h"
+#include "refs.h"
+#include "refs/refs-internal.h"
+#include "run-command.h"
+#include "hook.h"
+#include "object-name.h"
+#include "object-store-ll.h"
+#include "object.h"
+#include "path.h"
+#include "tag.h"
+#include "submodule.h"
+#include "worktree.h"
+#include "strvec.h"
+#include "repository.h"
+#include "setup.h"
+#include "sigchain.h"
+#include "date.h"
+#include "commit.h"
+#include "wildmatch.h"
+
+/*
+ * List of all available backends
+ */
+static struct ref_storage_be *refs_backends = &refs_be_files;
+
+static struct ref_storage_be *find_ref_storage_backend(const char *name)
+{
+	struct ref_storage_be *be;
+	for (be = refs_backends; be; be = be->next)
+		if (!strcmp(be->name, name))
+			return be;
+	return NULL;
+}
+
+/*
+ * How to handle various characters in refnames:
+ * 0: An acceptable character for refs
+ * 1: End-of-component
+ * 2: ., look for a preceding . to reject .. in refs
+ * 3: {, look for a preceding @ to reject @{ in refs
+ * 4: A bad character: ASCII control characters, and
+ *    ":", "?", "[", "\", "^", "~", SP, or TAB
+ * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
+ */
+static unsigned char refname_disposition[256] = {
+	1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+	4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
+};
+
+struct ref_namespace_info ref_namespace[] = {
+	[NAMESPACE_HEAD] = {
+		.ref = "HEAD",
+		.decoration = DECORATION_REF_HEAD,
+		.exact = 1,
+	},
+	[NAMESPACE_BRANCHES] = {
+		.ref = "refs/heads/",
+		.decoration = DECORATION_REF_LOCAL,
+	},
+	[NAMESPACE_TAGS] = {
+		.ref = "refs/tags/",
+		.decoration = DECORATION_REF_TAG,
+	},
+	[NAMESPACE_REMOTE_REFS] = {
+		/*
+		 * The default refspec for new remotes copies refs from
+		 * refs/heads/ on the remote into refs/remotes/<remote>/.
+		 * As such, "refs/remotes/" has special handling.
+		 */
+		.ref = "refs/remotes/",
+		.decoration = DECORATION_REF_REMOTE,
+	},
+	[NAMESPACE_STASH] = {
+		/*
+		 * The single ref "refs/stash" stores the latest stash.
+		 * Older stashes can be found in the reflog.
+		 */
+		.ref = "refs/stash",
+		.exact = 1,
+		.decoration = DECORATION_REF_STASH,
+	},
+	[NAMESPACE_REPLACE] = {
+		/*
+		 * This namespace allows Git to act as if one object ID
+		 * points to the content of another. Unlike the other
+		 * ref namespaces, this one can be changed by the
+		 * GIT_REPLACE_REF_BASE environment variable. This
+		 * .namespace value will be overwritten in setup_git_env().
+		 */
+		.ref = "refs/replace/",
+		.decoration = DECORATION_GRAFTED,
+	},
+	[NAMESPACE_NOTES] = {
+		/*
+		 * The refs/notes/commit ref points to the tip of a
+		 * parallel commit history that adds metadata to commits
+		 * in the normal history. This ref can be overwritten
+		 * by the core.notesRef config variable or the
+		 * GIT_NOTES_REFS environment variable.
+		 */
+		.ref = "refs/notes/commit",
+		.exact = 1,
+	},
+	[NAMESPACE_PREFETCH] = {
+		/*
+		 * Prefetch refs are written by the background 'fetch'
+		 * maintenance task. It allows faster foreground fetches
+		 * by advertising these previously-downloaded tips without
+		 * updating refs/remotes/ without user intervention.
+		 */
+		.ref = "refs/prefetch/",
+	},
+	[NAMESPACE_REWRITTEN] = {
+		/*
+		 * Rewritten refs are used by the 'label' command in the
+		 * sequencer. These are particularly useful during an
+		 * interactive rebase that uses the 'merge' command.
+		 */
+		.ref = "refs/rewritten/",
+	},
+};
+
+void update_ref_namespace(enum ref_namespace namespace, char *ref)
+{
+	struct ref_namespace_info *info = &ref_namespace[namespace];
+	if (info->ref_updated)
+		free(info->ref);
+	info->ref = ref;
+	info->ref_updated = 1;
+}
+
+/*
+ * Try to read one refname component from the front of refname.
+ * Return the length of the component found, or -1 if the component is
+ * not legal.  It is legal if it is something reasonable to have under
+ * ".git/refs/"; We do not like it if:
+ *
+ * - it begins with ".", or
+ * - it has double dots "..", or
+ * - it has ASCII control characters, or
+ * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
+ * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
+ * - it ends with a "/", or
+ * - it ends with ".lock", or
+ * - it contains a "@{" portion
+ *
+ * When sanitized is not NULL, instead of rejecting the input refname
+ * as an error, try to come up with a usable replacement for the input
+ * refname in it.
+ */
+static int check_refname_component(const char *refname, int *flags,
+				   struct strbuf *sanitized)
+{
+	const char *cp;
+	char last = '\0';
+	size_t component_start = 0; /* garbage - not a reasonable initial value */
+
+	if (sanitized)
+		component_start = sanitized->len;
+
+	for (cp = refname; ; cp++) {
+		int ch = *cp & 255;
+		unsigned char disp = refname_disposition[ch];
+
+		if (sanitized && disp != 1)
+			strbuf_addch(sanitized, ch);
+
+		switch (disp) {
+		case 1:
+			goto out;
+		case 2:
+			if (last == '.') { /* Refname contains "..". */
+				if (sanitized)
+					/* collapse ".." to single "." */
+					strbuf_setlen(sanitized, sanitized->len - 1);
+				else
+					return -1;
+			}
+			break;
+		case 3:
+			if (last == '@') { /* Refname contains "@{". */
+				if (sanitized)
+					sanitized->buf[sanitized->len-1] = '-';
+				else
+					return -1;
+			}
+			break;
+		case 4:
+			/* forbidden char */
+			if (sanitized)
+				sanitized->buf[sanitized->len-1] = '-';
+			else
+				return -1;
+			break;
+		case 5:
+			if (!(*flags & REFNAME_REFSPEC_PATTERN)) {
+				/* refspec can't be a pattern */
+				if (sanitized)
+					sanitized->buf[sanitized->len-1] = '-';
+				else
+					return -1;
+			}
+
+			/*
+			 * Unset the pattern flag so that we only accept
+			 * a single asterisk for one side of refspec.
+			 */
+			*flags &= ~ REFNAME_REFSPEC_PATTERN;
+			break;
+		}
+		last = ch;
+	}
+out:
+	if (cp == refname)
+		return 0; /* Component has zero length. */
+
+	if (refname[0] == '.') { /* Component starts with '.'. */
+		if (sanitized)
+			sanitized->buf[component_start] = '-';
+		else
+			return -1;
+	}
+	if (cp - refname >= LOCK_SUFFIX_LEN &&
+	    !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN)) {
+		if (!sanitized)
+			return -1;
+		/* Refname ends with ".lock". */
+		while (strbuf_strip_suffix(sanitized, LOCK_SUFFIX)) {
+			/* try again in case we have .lock.lock */
+		}
+	}
+	return cp - refname;
+}
+
+static int check_or_sanitize_refname(const char *refname, int flags,
+				     struct strbuf *sanitized)
+{
+	int component_len, component_count = 0;
+
+	if (!strcmp(refname, "@")) {
+		/* Refname is a single character '@'. */
+		if (sanitized)
+			strbuf_addch(sanitized, '-');
+		else
+			return -1;
+	}
+
+	while (1) {
+		if (sanitized && sanitized->len)
+			strbuf_complete(sanitized, '/');
+
+		/* We are at the start of a path component. */
+		component_len = check_refname_component(refname, &flags,
+							sanitized);
+		if (sanitized && component_len == 0)
+			; /* OK, omit empty component */
+		else if (component_len <= 0)
+			return -1;
+
+		component_count++;
+		if (refname[component_len] == '\0')
+			break;
+		/* Skip to next component. */
+		refname += component_len + 1;
+	}
+
+	if (refname[component_len - 1] == '.') {
+		/* Refname ends with '.'. */
+		if (sanitized)
+			; /* omit ending dot */
+		else
+			return -1;
+	}
+	if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
+		return -1; /* Refname has only one component. */
+	return 0;
+}
+
+int check_refname_format(const char *refname, int flags)
+{
+	return check_or_sanitize_refname(refname, flags, NULL);
+}
+
+void sanitize_refname_component(const char *refname, struct strbuf *out)
+{
+	if (check_or_sanitize_refname(refname, REFNAME_ALLOW_ONELEVEL, out))
+		BUG("sanitizing refname '%s' check returned error", refname);
+}
+
+int refname_is_safe(const char *refname)
+{
+	const char *rest;
+
+	if (skip_prefix(refname, "refs/", &rest)) {
+		char *buf;
+		int result;
+		size_t restlen = strlen(rest);
+
+		/* rest must not be empty, or start or end with "/" */
+		if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
+			return 0;
+
+		/*
+		 * Does the refname try to escape refs/?
+		 * For example: refs/foo/../bar is safe but refs/foo/../../bar
+		 * is not.
+		 */
+		buf = xmallocz(restlen);
+		result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
+		free(buf);
+		return result;
+	}
+
+	do {
+		if (!isupper(*refname) && *refname != '_')
+			return 0;
+		refname++;
+	} while (*refname);
+	return 1;
+}
+
+/*
+ * Return true if refname, which has the specified oid and flags, can
+ * be resolved to an object in the database. If the referred-to object
+ * does not exist, emit a warning and return false.
+ */
+int ref_resolves_to_object(const char *refname,
+			   struct repository *repo,
+			   const struct object_id *oid,
+			   unsigned int flags)
+{
+	if (flags & REF_ISBROKEN)
+		return 0;
+	if (!repo_has_object_file(repo, oid)) {
+		error(_("%s does not point to a valid object!"), refname);
+		return 0;
+	}
+	return 1;
+}
+
+char *refs_resolve_refdup(struct ref_store *refs,
+			  const char *refname, int resolve_flags,
+			  struct object_id *oid, int *flags)
+{
+	const char *result;
+
+	result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
+					 oid, flags);
+	return xstrdup_or_null(result);
+}
+
+char *resolve_refdup(const char *refname, int resolve_flags,
+		     struct object_id *oid, int *flags)
+{
+	return refs_resolve_refdup(get_main_ref_store(the_repository),
+				   refname, resolve_flags,
+				   oid, flags);
+}
+
+/* The argument to for_each_filter_refs */
+struct for_each_ref_filter {
+	const char *pattern;
+	const char *prefix;
+	each_ref_fn *fn;
+	void *cb_data;
+};
+
+int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
+{
+	struct ref_store *refs = get_main_ref_store(the_repository);
+
+	if (refs_resolve_ref_unsafe(refs, refname, resolve_flags,
+				    oid, flags))
+		return 0;
+	return -1;
+}
+
+int read_ref(const char *refname, struct object_id *oid)
+{
+	return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
+}
+
+int refs_ref_exists(struct ref_store *refs, const char *refname)
+{
+	return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING,
+					 NULL, NULL);
+}
+
+int ref_exists(const char *refname)
+{
+	return refs_ref_exists(get_main_ref_store(the_repository), refname);
+}
+
+static int for_each_filter_refs(const char *refname,
+				const struct object_id *oid,
+				int flags, void *data)
+{
+	struct for_each_ref_filter *filter = data;
+
+	if (wildmatch(filter->pattern, refname, 0))
+		return 0;
+	if (filter->prefix)
+		skip_prefix(refname, filter->prefix, &refname);
+	return filter->fn(refname, oid, flags, filter->cb_data);
+}
+
+enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
+{
+	struct object *o = lookup_unknown_object(the_repository, name);
+
+	if (o->type == OBJ_NONE) {
+		int type = oid_object_info(the_repository, name, NULL);
+		if (type < 0 || !object_as_type(o, type, 0))
+			return PEEL_INVALID;
+	}
+
+	if (o->type != OBJ_TAG)
+		return PEEL_NON_TAG;
+
+	o = deref_tag_noverify(o);
+	if (!o)
+		return PEEL_INVALID;
+
+	oidcpy(oid, &o->oid);
+	return PEEL_PEELED;
+}
+
+struct warn_if_dangling_data {
+	FILE *fp;
+	const char *refname;
+	const struct string_list *refnames;
+	const char *msg_fmt;
+};
+
+static int warn_if_dangling_symref(const char *refname,
+				   const struct object_id *oid UNUSED,
+				   int flags, void *cb_data)
+{
+	struct warn_if_dangling_data *d = cb_data;
+	const char *resolves_to;
+
+	if (!(flags & REF_ISSYMREF))
+		return 0;
+
+	resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
+	if (!resolves_to
+	    || (d->refname
+		? strcmp(resolves_to, d->refname)
+		: !string_list_has_string(d->refnames, resolves_to))) {
+		return 0;
+	}
+
+	fprintf(d->fp, d->msg_fmt, refname);
+	fputc('\n', d->fp);
+	return 0;
+}
+
+void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
+{
+	struct warn_if_dangling_data data;
+
+	data.fp = fp;
+	data.refname = refname;
+	data.refnames = NULL;
+	data.msg_fmt = msg_fmt;
+	for_each_rawref(warn_if_dangling_symref, &data);
+}
+
+void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
+{
+	struct warn_if_dangling_data data;
+
+	data.fp = fp;
+	data.refname = NULL;
+	data.refnames = refnames;
+	data.msg_fmt = msg_fmt;
+	for_each_rawref(warn_if_dangling_symref, &data);
+}
+
+int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
+}
+
+int for_each_tag_ref(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_tag_ref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
+}
+
+int for_each_branch_ref(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_branch_ref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
+}
+
+int for_each_remote_ref(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_remote_ref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+int head_ref_namespaced(each_ref_fn fn, void *cb_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int ret = 0;
+	struct object_id oid;
+	int flag;
+
+	strbuf_addf(&buf, "%sHEAD", get_git_namespace());
+	if (!read_ref_full(buf.buf, RESOLVE_REF_READING, &oid, &flag))
+		ret = fn(buf.buf, &oid, flag, cb_data);
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+void normalize_glob_ref(struct string_list_item *item, const char *prefix,
+			const char *pattern)
+{
+	struct strbuf normalized_pattern = STRBUF_INIT;
+
+	if (*pattern == '/')
+		BUG("pattern must not start with '/'");
+
+	if (prefix)
+		strbuf_addstr(&normalized_pattern, prefix);
+	else if (!starts_with(pattern, "refs/") &&
+		   strcmp(pattern, "HEAD"))
+		strbuf_addstr(&normalized_pattern, "refs/");
+	/*
+	 * NEEDSWORK: Special case other symrefs such as REBASE_HEAD,
+	 * MERGE_HEAD, etc.
+	 */
+
+	strbuf_addstr(&normalized_pattern, pattern);
+	strbuf_strip_suffix(&normalized_pattern, "/");
+
+	item->string = strbuf_detach(&normalized_pattern, NULL);
+	item->util = has_glob_specials(pattern) ? NULL : item->string;
+	strbuf_release(&normalized_pattern);
+}
+
+int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
+	const char *prefix, void *cb_data)
+{
+	struct strbuf real_pattern = STRBUF_INIT;
+	struct for_each_ref_filter filter;
+	int ret;
+
+	if (!prefix && !starts_with(pattern, "refs/"))
+		strbuf_addstr(&real_pattern, "refs/");
+	else if (prefix)
+		strbuf_addstr(&real_pattern, prefix);
+	strbuf_addstr(&real_pattern, pattern);
+
+	if (!has_glob_specials(pattern)) {
+		/* Append implied '/' '*' if not present. */
+		strbuf_complete(&real_pattern, '/');
+		/* No need to check for '*', there is none. */
+		strbuf_addch(&real_pattern, '*');
+	}
+
+	filter.pattern = real_pattern.buf;
+	filter.prefix = prefix;
+	filter.fn = fn;
+	filter.cb_data = cb_data;
+	ret = for_each_ref(for_each_filter_refs, &filter);
+
+	strbuf_release(&real_pattern);
+	return ret;
+}
+
+int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
+{
+	return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
+}
+
+const char *prettify_refname(const char *name)
+{
+	if (skip_prefix(name, "refs/heads/", &name) ||
+	    skip_prefix(name, "refs/tags/", &name) ||
+	    skip_prefix(name, "refs/remotes/", &name))
+		; /* nothing */
+	return name;
+}
+
+static const char *ref_rev_parse_rules[] = {
+	"%.*s",
+	"refs/%.*s",
+	"refs/tags/%.*s",
+	"refs/heads/%.*s",
+	"refs/remotes/%.*s",
+	"refs/remotes/%.*s/HEAD",
+	NULL
+};
+
+#define NUM_REV_PARSE_RULES (ARRAY_SIZE(ref_rev_parse_rules) - 1)
+
+/*
+ * Is it possible that the caller meant full_name with abbrev_name?
+ * If so return a non-zero value to signal "yes"; the magnitude of
+ * the returned value gives the precedence used for disambiguation.
+ *
+ * If abbrev_name cannot mean full_name, return 0.
+ */
+int refname_match(const char *abbrev_name, const char *full_name)
+{
+	const char **p;
+	const int abbrev_name_len = strlen(abbrev_name);
+	const int num_rules = NUM_REV_PARSE_RULES;
+
+	for (p = ref_rev_parse_rules; *p; p++)
+		if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name)))
+			return &ref_rev_parse_rules[num_rules] - p;
+
+	return 0;
+}
+
+/*
+ * Given a 'prefix' expand it by the rules in 'ref_rev_parse_rules' and add
+ * the results to 'prefixes'
+ */
+void expand_ref_prefix(struct strvec *prefixes, const char *prefix)
+{
+	const char **p;
+	int len = strlen(prefix);
+
+	for (p = ref_rev_parse_rules; *p; p++)
+		strvec_pushf(prefixes, *p, len, prefix);
+}
+
+static const char default_branch_name_advice[] = N_(
+"Using '%s' as the name for the initial branch. This default branch name\n"
+"is subject to change. To configure the initial branch name to use in all\n"
+"of your new repositories, which will suppress this warning, call:\n"
+"\n"
+"\tgit config --global init.defaultBranch <name>\n"
+"\n"
+"Names commonly chosen instead of 'master' are 'main', 'trunk' and\n"
+"'development'. The just-created branch can be renamed via this command:\n"
+"\n"
+"\tgit branch -m <name>\n"
+);
+
+char *repo_default_branch_name(struct repository *r, int quiet)
+{
+	const char *config_key = "init.defaultbranch";
+	const char *config_display_key = "init.defaultBranch";
+	char *ret = NULL, *full_ref;
+	const char *env = getenv("GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME");
+
+	if (env && *env)
+		ret = xstrdup(env);
+	else if (repo_config_get_string(r, config_key, &ret) < 0)
+		die(_("could not retrieve `%s`"), config_display_key);
+
+	if (!ret) {
+		ret = xstrdup("master");
+		if (!quiet)
+			advise(_(default_branch_name_advice), ret);
+	}
+
+	full_ref = xstrfmt("refs/heads/%s", ret);
+	if (check_refname_format(full_ref, 0))
+		die(_("invalid branch name: %s = %s"), config_display_key, ret);
+	free(full_ref);
+
+	return ret;
+}
+
+const char *git_default_branch_name(int quiet)
+{
+	static char *ret;
+
+	if (!ret)
+		ret = repo_default_branch_name(the_repository, quiet);
+
+	return ret;
+}
+
+/*
+ * *string and *len will only be substituted, and *string returned (for
+ * later free()ing) if the string passed in is a magic short-hand form
+ * to name a branch.
+ */
+static char *substitute_branch_name(struct repository *r,
+				    const char **string, int *len,
+				    int nonfatal_dangling_mark)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct interpret_branch_name_options options = {
+		.nonfatal_dangling_mark = nonfatal_dangling_mark
+	};
+	int ret = repo_interpret_branch_name(r, *string, *len, &buf, &options);
+
+	if (ret == *len) {
+		size_t size;
+		*string = strbuf_detach(&buf, &size);
+		*len = size;
+		return (char *)*string;
+	}
+
+	return NULL;
+}
+
+int repo_dwim_ref(struct repository *r, const char *str, int len,
+		  struct object_id *oid, char **ref, int nonfatal_dangling_mark)
+{
+	char *last_branch = substitute_branch_name(r, &str, &len,
+						   nonfatal_dangling_mark);
+	int   refs_found  = expand_ref(r, str, len, oid, ref);
+	free(last_branch);
+	return refs_found;
+}
+
+int expand_ref(struct repository *repo, const char *str, int len,
+	       struct object_id *oid, char **ref)
+{
+	const char **p, *r;
+	int refs_found = 0;
+	struct strbuf fullref = STRBUF_INIT;
+
+	*ref = NULL;
+	for (p = ref_rev_parse_rules; *p; p++) {
+		struct object_id oid_from_ref;
+		struct object_id *this_result;
+		int flag;
+		struct ref_store *refs = get_main_ref_store(repo);
+
+		this_result = refs_found ? &oid_from_ref : oid;
+		strbuf_reset(&fullref);
+		strbuf_addf(&fullref, *p, len, str);
+		r = refs_resolve_ref_unsafe(refs, fullref.buf,
+					    RESOLVE_REF_READING,
+					    this_result, &flag);
+		if (r) {
+			if (!refs_found++)
+				*ref = xstrdup(r);
+			if (!warn_ambiguous_refs)
+				break;
+		} else if ((flag & REF_ISSYMREF) && strcmp(fullref.buf, "HEAD")) {
+			warning(_("ignoring dangling symref %s"), fullref.buf);
+		} else if ((flag & REF_ISBROKEN) && strchr(fullref.buf, '/')) {
+			warning(_("ignoring broken ref %s"), fullref.buf);
+		}
+	}
+	strbuf_release(&fullref);
+	return refs_found;
+}
+
+int repo_dwim_log(struct repository *r, const char *str, int len,
+		  struct object_id *oid, char **log)
+{
+	struct ref_store *refs = get_main_ref_store(r);
+	char *last_branch = substitute_branch_name(r, &str, &len, 0);
+	const char **p;
+	int logs_found = 0;
+	struct strbuf path = STRBUF_INIT;
+
+	*log = NULL;
+	for (p = ref_rev_parse_rules; *p; p++) {
+		struct object_id hash;
+		const char *ref, *it;
+
+		strbuf_reset(&path);
+		strbuf_addf(&path, *p, len, str);
+		ref = refs_resolve_ref_unsafe(refs, path.buf,
+					      RESOLVE_REF_READING,
+					      oid ? &hash : NULL, NULL);
+		if (!ref)
+			continue;
+		if (refs_reflog_exists(refs, path.buf))
+			it = path.buf;
+		else if (strcmp(ref, path.buf) &&
+			 refs_reflog_exists(refs, ref))
+			it = ref;
+		else
+			continue;
+		if (!logs_found++) {
+			*log = xstrdup(it);
+			if (oid)
+				oidcpy(oid, &hash);
+		}
+		if (!warn_ambiguous_refs)
+			break;
+	}
+	strbuf_release(&path);
+	free(last_branch);
+	return logs_found;
+}
+
+int dwim_log(const char *str, int len, struct object_id *oid, char **log)
+{
+	return repo_dwim_log(the_repository, str, len, oid, log);
+}
+
+int is_per_worktree_ref(const char *refname)
+{
+	return starts_with(refname, "refs/worktree/") ||
+	       starts_with(refname, "refs/bisect/") ||
+	       starts_with(refname, "refs/rewritten/");
+}
+
+static int is_pseudoref_syntax(const char *refname)
+{
+	const char *c;
+
+	for (c = refname; *c; c++) {
+		if (!isupper(*c) && *c != '-' && *c != '_')
+			return 0;
+	}
+
+	/*
+	 * HEAD is not a pseudoref, but it certainly uses the
+	 * pseudoref syntax.
+	 */
+	return 1;
+}
+
+static int is_current_worktree_ref(const char *ref) {
+	return is_pseudoref_syntax(ref) || is_per_worktree_ref(ref);
+}
+
+enum ref_worktree_type parse_worktree_ref(const char *maybe_worktree_ref,
+					  const char **worktree_name, int *worktree_name_length,
+					  const char **bare_refname)
+{
+	const char *name_dummy;
+	int name_length_dummy;
+	const char *ref_dummy;
+
+	if (!worktree_name)
+		worktree_name = &name_dummy;
+	if (!worktree_name_length)
+		worktree_name_length = &name_length_dummy;
+	if (!bare_refname)
+		bare_refname = &ref_dummy;
+
+	if (skip_prefix(maybe_worktree_ref, "worktrees/", bare_refname)) {
+		const char *slash = strchr(*bare_refname, '/');
+
+		*worktree_name = *bare_refname;
+		if (!slash) {
+			*worktree_name_length = strlen(*worktree_name);
+
+			/* This is an error condition, and the caller tell because the bare_refname is "" */
+			*bare_refname = *worktree_name + *worktree_name_length;
+			return REF_WORKTREE_OTHER;
+		}
+
+		*worktree_name_length = slash - *bare_refname;
+		*bare_refname = slash + 1;
+
+		if (is_current_worktree_ref(*bare_refname))
+			return REF_WORKTREE_OTHER;
+	}
+
+	*worktree_name = NULL;
+	*worktree_name_length = 0;
+
+	if (skip_prefix(maybe_worktree_ref, "main-worktree/", bare_refname)
+	    && is_current_worktree_ref(*bare_refname))
+		return REF_WORKTREE_MAIN;
+
+	*bare_refname = maybe_worktree_ref;
+	if (is_current_worktree_ref(maybe_worktree_ref))
+		return REF_WORKTREE_CURRENT;
+
+	return REF_WORKTREE_SHARED;
+}
+
+long get_files_ref_lock_timeout_ms(void)
+{
+	static int configured = 0;
+
+	/* The default timeout is 100 ms: */
+	static int timeout_ms = 100;
+
+	if (!configured) {
+		git_config_get_int("core.filesreflocktimeout", &timeout_ms);
+		configured = 1;
+	}
+
+	return timeout_ms;
+}
+
+int refs_delete_ref(struct ref_store *refs, const char *msg,
+		    const char *refname,
+		    const struct object_id *old_oid,
+		    unsigned int flags)
+{
+	struct ref_transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
+
+	transaction = ref_store_transaction_begin(refs, &err);
+	if (!transaction ||
+	    ref_transaction_delete(transaction, refname, old_oid,
+				   flags, msg, &err) ||
+	    ref_transaction_commit(transaction, &err)) {
+		error("%s", err.buf);
+		ref_transaction_free(transaction);
+		strbuf_release(&err);
+		return 1;
+	}
+	ref_transaction_free(transaction);
+	strbuf_release(&err);
+	return 0;
+}
+
+int delete_ref(const char *msg, const char *refname,
+	       const struct object_id *old_oid, unsigned int flags)
+{
+	return refs_delete_ref(get_main_ref_store(the_repository), msg, refname,
+			       old_oid, flags);
+}
+
+static void copy_reflog_msg(struct strbuf *sb, const char *msg)
+{
+	char c;
+	int wasspace = 1;
+
+	while ((c = *msg++)) {
+		if (wasspace && isspace(c))
+			continue;
+		wasspace = isspace(c);
+		if (wasspace)
+			c = ' ';
+		strbuf_addch(sb, c);
+	}
+	strbuf_rtrim(sb);
+}
+
+static char *normalize_reflog_message(const char *msg)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	if (msg && *msg)
+		copy_reflog_msg(&sb, msg);
+	return strbuf_detach(&sb, NULL);
+}
+
+int should_autocreate_reflog(const char *refname)
+{
+	switch (log_all_ref_updates) {
+	case LOG_REFS_ALWAYS:
+		return 1;
+	case LOG_REFS_NORMAL:
+		return starts_with(refname, "refs/heads/") ||
+			starts_with(refname, "refs/remotes/") ||
+			starts_with(refname, "refs/notes/") ||
+			!strcmp(refname, "HEAD");
+	default:
+		return 0;
+	}
+}
+
+int is_branch(const char *refname)
+{
+	return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
+}
+
+struct read_ref_at_cb {
+	const char *refname;
+	timestamp_t at_time;
+	int cnt;
+	int reccnt;
+	struct object_id *oid;
+	int found_it;
+
+	struct object_id ooid;
+	struct object_id noid;
+	int tz;
+	timestamp_t date;
+	char **msg;
+	timestamp_t *cutoff_time;
+	int *cutoff_tz;
+	int *cutoff_cnt;
+};
+
+static void set_read_ref_cutoffs(struct read_ref_at_cb *cb,
+		timestamp_t timestamp, int tz, const char *message)
+{
+	if (cb->msg)
+		*cb->msg = xstrdup(message);
+	if (cb->cutoff_time)
+		*cb->cutoff_time = timestamp;
+	if (cb->cutoff_tz)
+		*cb->cutoff_tz = tz;
+	if (cb->cutoff_cnt)
+		*cb->cutoff_cnt = cb->reccnt;
+}
+
+static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
+			   const char *email UNUSED,
+			   timestamp_t timestamp, int tz,
+			   const char *message, void *cb_data)
+{
+	struct read_ref_at_cb *cb = cb_data;
+	int reached_count;
+
+	cb->tz = tz;
+	cb->date = timestamp;
+
+	/*
+	 * It is not possible for cb->cnt == 0 on the first iteration because
+	 * that special case is handled in read_ref_at().
+	 */
+	if (cb->cnt > 0)
+		cb->cnt--;
+	reached_count = cb->cnt == 0 && !is_null_oid(ooid);
+	if (timestamp <= cb->at_time || reached_count) {
+		set_read_ref_cutoffs(cb, timestamp, tz, message);
+		/*
+		 * we have not yet updated cb->[n|o]oid so they still
+		 * hold the values for the previous record.
+		 */
+		if (!is_null_oid(&cb->ooid) && !oideq(&cb->ooid, noid))
+			warning(_("log for ref %s has gap after %s"),
+					cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
+		if (reached_count)
+			oidcpy(cb->oid, ooid);
+		else if (!is_null_oid(&cb->ooid) || cb->date == cb->at_time)
+			oidcpy(cb->oid, noid);
+		else if (!oideq(noid, cb->oid))
+			warning(_("log for ref %s unexpectedly ended on %s"),
+				cb->refname, show_date(cb->date, cb->tz,
+						       DATE_MODE(RFC2822)));
+		cb->found_it = 1;
+	}
+	cb->reccnt++;
+	oidcpy(&cb->ooid, ooid);
+	oidcpy(&cb->noid, noid);
+	return cb->found_it;
+}
+
+static int read_ref_at_ent_newest(struct object_id *ooid UNUSED,
+				  struct object_id *noid,
+				  const char *email UNUSED,
+				  timestamp_t timestamp, int tz,
+				  const char *message, void *cb_data)
+{
+	struct read_ref_at_cb *cb = cb_data;
+
+	set_read_ref_cutoffs(cb, timestamp, tz, message);
+	oidcpy(cb->oid, noid);
+	/* We just want the first entry */
+	return 1;
+}
+
+static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
+				  const char *email UNUSED,
+				  timestamp_t timestamp, int tz,
+				  const char *message, void *cb_data)
+{
+	struct read_ref_at_cb *cb = cb_data;
+
+	set_read_ref_cutoffs(cb, timestamp, tz, message);
+	oidcpy(cb->oid, ooid);
+	if (is_null_oid(cb->oid))
+		oidcpy(cb->oid, noid);
+	/* We just want the first entry */
+	return 1;
+}
+
+int read_ref_at(struct ref_store *refs, const char *refname,
+		unsigned int flags, timestamp_t at_time, int cnt,
+		struct object_id *oid, char **msg,
+		timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
+{
+	struct read_ref_at_cb cb;
+
+	memset(&cb, 0, sizeof(cb));
+	cb.refname = refname;
+	cb.at_time = at_time;
+	cb.cnt = cnt;
+	cb.msg = msg;
+	cb.cutoff_time = cutoff_time;
+	cb.cutoff_tz = cutoff_tz;
+	cb.cutoff_cnt = cutoff_cnt;
+	cb.oid = oid;
+
+	if (cb.cnt == 0) {
+		refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent_newest, &cb);
+		return 0;
+	}
+
+	refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent, &cb);
+
+	if (!cb.reccnt) {
+		if (flags & GET_OID_QUIETLY)
+			exit(128);
+		else
+			die(_("log for %s is empty"), refname);
+	}
+	if (cb.found_it)
+		return 0;
+
+	refs_for_each_reflog_ent(refs, refname, read_ref_at_ent_oldest, &cb);
+
+	return 1;
+}
+
+struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
+						    struct strbuf *err)
+{
+	struct ref_transaction *tr;
+	assert(err);
+
+	CALLOC_ARRAY(tr, 1);
+	tr->ref_store = refs;
+	return tr;
+}
+
+struct ref_transaction *ref_transaction_begin(struct strbuf *err)
+{
+	return ref_store_transaction_begin(get_main_ref_store(the_repository), err);
+}
+
+void ref_transaction_free(struct ref_transaction *transaction)
+{
+	size_t i;
+
+	if (!transaction)
+		return;
+
+	switch (transaction->state) {
+	case REF_TRANSACTION_OPEN:
+	case REF_TRANSACTION_CLOSED:
+		/* OK */
+		break;
+	case REF_TRANSACTION_PREPARED:
+		BUG("free called on a prepared reference transaction");
+		break;
+	default:
+		BUG("unexpected reference transaction state");
+		break;
+	}
+
+	for (i = 0; i < transaction->nr; i++) {
+		free(transaction->updates[i]->msg);
+		free(transaction->updates[i]);
+	}
+	free(transaction->updates);
+	free(transaction);
+}
+
+struct ref_update *ref_transaction_add_update(
+		struct ref_transaction *transaction,
+		const char *refname, unsigned int flags,
+		const struct object_id *new_oid,
+		const struct object_id *old_oid,
+		const char *msg)
+{
+	struct ref_update *update;
+
+	if (transaction->state != REF_TRANSACTION_OPEN)
+		BUG("update called for transaction that is not open");
+
+	FLEX_ALLOC_STR(update, refname, refname);
+	ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
+	transaction->updates[transaction->nr++] = update;
+
+	update->flags = flags;
+
+	if (flags & REF_HAVE_NEW)
+		oidcpy(&update->new_oid, new_oid);
+	if (flags & REF_HAVE_OLD)
+		oidcpy(&update->old_oid, old_oid);
+	update->msg = normalize_reflog_message(msg);
+	return update;
+}
+
+int ref_transaction_update(struct ref_transaction *transaction,
+			   const char *refname,
+			   const struct object_id *new_oid,
+			   const struct object_id *old_oid,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	assert(err);
+
+	if (!(flags & REF_SKIP_REFNAME_VERIFICATION) &&
+	    ((new_oid && !is_null_oid(new_oid)) ?
+		     check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
+			   !refname_is_safe(refname))) {
+		strbuf_addf(err, _("refusing to update ref with bad name '%s'"),
+			    refname);
+		return -1;
+	}
+
+	if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
+		BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
+
+	/*
+	 * Clear flags outside the allowed set; this should be a noop because
+	 * of the BUG() check above, but it works around a -Wnonnull warning
+	 * with some versions of "gcc -O3".
+	 */
+	flags &= REF_TRANSACTION_UPDATE_ALLOWED_FLAGS;
+
+	flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
+
+	ref_transaction_add_update(transaction, refname, flags,
+				   new_oid, old_oid, msg);
+	return 0;
+}
+
+int ref_transaction_create(struct ref_transaction *transaction,
+			   const char *refname,
+			   const struct object_id *new_oid,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	if (!new_oid || is_null_oid(new_oid)) {
+		strbuf_addf(err, "'%s' has a null OID", refname);
+		return 1;
+	}
+	return ref_transaction_update(transaction, refname, new_oid,
+				      null_oid(), flags, msg, err);
+}
+
+int ref_transaction_delete(struct ref_transaction *transaction,
+			   const char *refname,
+			   const struct object_id *old_oid,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	if (old_oid && is_null_oid(old_oid))
+		BUG("delete called with old_oid set to zeros");
+	return ref_transaction_update(transaction, refname,
+				      null_oid(), old_oid,
+				      flags, msg, err);
+}
+
+int ref_transaction_verify(struct ref_transaction *transaction,
+			   const char *refname,
+			   const struct object_id *old_oid,
+			   unsigned int flags,
+			   struct strbuf *err)
+{
+	if (!old_oid)
+		BUG("verify called with old_oid set to NULL");
+	return ref_transaction_update(transaction, refname,
+				      NULL, old_oid,
+				      flags, NULL, err);
+}
+
+int refs_update_ref(struct ref_store *refs, const char *msg,
+		    const char *refname, const struct object_id *new_oid,
+		    const struct object_id *old_oid, unsigned int flags,
+		    enum action_on_err onerr)
+{
+	struct ref_transaction *t = NULL;
+	struct strbuf err = STRBUF_INIT;
+	int ret = 0;
+
+	t = ref_store_transaction_begin(refs, &err);
+	if (!t ||
+	    ref_transaction_update(t, refname, new_oid, old_oid, flags, msg,
+				   &err) ||
+	    ref_transaction_commit(t, &err)) {
+		ret = 1;
+		ref_transaction_free(t);
+	}
+	if (ret) {
+		const char *str = _("update_ref failed for ref '%s': %s");
+
+		switch (onerr) {
+		case UPDATE_REFS_MSG_ON_ERR:
+			error(str, refname, err.buf);
+			break;
+		case UPDATE_REFS_DIE_ON_ERR:
+			die(str, refname, err.buf);
+			break;
+		case UPDATE_REFS_QUIET_ON_ERR:
+			break;
+		}
+		strbuf_release(&err);
+		return 1;
+	}
+	strbuf_release(&err);
+	if (t)
+		ref_transaction_free(t);
+	return 0;
+}
+
+int update_ref(const char *msg, const char *refname,
+	       const struct object_id *new_oid,
+	       const struct object_id *old_oid,
+	       unsigned int flags, enum action_on_err onerr)
+{
+	return refs_update_ref(get_main_ref_store(the_repository), msg, refname, new_oid,
+			       old_oid, flags, onerr);
+}
+
+/*
+ * Check that the string refname matches a rule of the form
+ * "{prefix}%.*s{suffix}". So "foo/bar/baz" would match the rule
+ * "foo/%.*s/baz", and return the string "bar".
+ */
+static const char *match_parse_rule(const char *refname, const char *rule,
+				    size_t *len)
+{
+	/*
+	 * Check that rule matches refname up to the first percent in the rule.
+	 * We can bail immediately if not, but otherwise we leave "rule" at the
+	 * %-placeholder, and "refname" at the start of the potential matched
+	 * name.
+	 */
+	while (*rule != '%') {
+		if (!*rule)
+			BUG("rev-parse rule did not have percent");
+		if (*refname++ != *rule++)
+			return NULL;
+	}
+
+	/*
+	 * Check that our "%" is the expected placeholder. This assumes there
+	 * are no other percents (placeholder or quoted) in the string, but
+	 * that is sufficient for our rev-parse rules.
+	 */
+	if (!skip_prefix(rule, "%.*s", &rule))
+		return NULL;
+
+	/*
+	 * And now check that our suffix (if any) matches.
+	 */
+	if (!strip_suffix(refname, rule, len))
+		return NULL;
+
+	return refname; /* len set by strip_suffix() */
+}
+
+char *refs_shorten_unambiguous_ref(struct ref_store *refs,
+				   const char *refname, int strict)
+{
+	int i;
+	struct strbuf resolved_buf = STRBUF_INIT;
+
+	/* skip first rule, it will always match */
+	for (i = NUM_REV_PARSE_RULES - 1; i > 0 ; --i) {
+		int j;
+		int rules_to_fail = i;
+		const char *short_name;
+		size_t short_name_len;
+
+		short_name = match_parse_rule(refname, ref_rev_parse_rules[i],
+					      &short_name_len);
+		if (!short_name)
+			continue;
+
+		/*
+		 * in strict mode, all (except the matched one) rules
+		 * must fail to resolve to a valid non-ambiguous ref
+		 */
+		if (strict)
+			rules_to_fail = NUM_REV_PARSE_RULES;
+
+		/*
+		 * check if the short name resolves to a valid ref,
+		 * but use only rules prior to the matched one
+		 */
+		for (j = 0; j < rules_to_fail; j++) {
+			const char *rule = ref_rev_parse_rules[j];
+
+			/* skip matched rule */
+			if (i == j)
+				continue;
+
+			/*
+			 * the short name is ambiguous, if it resolves
+			 * (with this previous rule) to a valid ref
+			 * read_ref() returns 0 on success
+			 */
+			strbuf_reset(&resolved_buf);
+			strbuf_addf(&resolved_buf, rule,
+				    cast_size_t_to_int(short_name_len),
+				    short_name);
+			if (refs_ref_exists(refs, resolved_buf.buf))
+				break;
+		}
+
+		/*
+		 * short name is non-ambiguous if all previous rules
+		 * haven't resolved to a valid ref
+		 */
+		if (j == rules_to_fail) {
+			strbuf_release(&resolved_buf);
+			return xmemdupz(short_name, short_name_len);
+		}
+	}
+
+	strbuf_release(&resolved_buf);
+	return xstrdup(refname);
+}
+
+char *shorten_unambiguous_ref(const char *refname, int strict)
+{
+	return refs_shorten_unambiguous_ref(get_main_ref_store(the_repository),
+					    refname, strict);
+}
+
+int parse_hide_refs_config(const char *var, const char *value, const char *section,
+			   struct strvec *hide_refs)
+{
+	const char *key;
+	if (!strcmp("transfer.hiderefs", var) ||
+	    (!parse_config_key(var, section, NULL, NULL, &key) &&
+	     !strcmp(key, "hiderefs"))) {
+		char *ref;
+		int len;
+
+		if (!value)
+			return config_error_nonbool(var);
+
+		/* drop const to remove trailing '/' characters */
+		ref = (char *)strvec_push(hide_refs, value);
+		len = strlen(ref);
+		while (len && ref[len - 1] == '/')
+			ref[--len] = '\0';
+	}
+	return 0;
+}
+
+int ref_is_hidden(const char *refname, const char *refname_full,
+		  const struct strvec *hide_refs)
+{
+	int i;
+
+	for (i = hide_refs->nr - 1; i >= 0; i--) {
+		const char *match = hide_refs->v[i];
+		const char *subject;
+		int neg = 0;
+		const char *p;
+
+		if (*match == '!') {
+			neg = 1;
+			match++;
+		}
+
+		if (*match == '^') {
+			subject = refname_full;
+			match++;
+		} else {
+			subject = refname;
+		}
+
+		/* refname can be NULL when namespaces are used. */
+		if (subject &&
+		    skip_prefix(subject, match, &p) &&
+		    (!*p || *p == '/'))
+			return !neg;
+	}
+	return 0;
+}
+
+const char **hidden_refs_to_excludes(const struct strvec *hide_refs)
+{
+	const char **pattern;
+	for (pattern = hide_refs->v; *pattern; pattern++) {
+		/*
+		 * We can't feed any excludes from hidden refs config
+		 * sections, since later rules may override previous
+		 * ones. For example, with rules "refs/foo" and
+		 * "!refs/foo/bar", we should show "refs/foo/bar" (and
+		 * everything underneath it), but the earlier exclusion
+		 * would cause us to skip all of "refs/foo".  We
+		 * likewise don't implement the namespace stripping
+		 * required for '^' rules.
+		 *
+		 * Both are possible to do, but complicated, so avoid
+		 * populating the jump list at all if we see either of
+		 * these patterns.
+		 */
+		if (**pattern == '!' || **pattern == '^')
+			return NULL;
+	}
+	return hide_refs->v;
+}
+
+const char *find_descendant_ref(const char *dirname,
+				const struct string_list *extras,
+				const struct string_list *skip)
+{
+	int pos;
+
+	if (!extras)
+		return NULL;
+
+	/*
+	 * Look at the place where dirname would be inserted into
+	 * extras. If there is an entry at that position that starts
+	 * with dirname (remember, dirname includes the trailing
+	 * slash) and is not in skip, then we have a conflict.
+	 */
+	for (pos = string_list_find_insert_index(extras, dirname, 0);
+	     pos < extras->nr; pos++) {
+		const char *extra_refname = extras->items[pos].string;
+
+		if (!starts_with(extra_refname, dirname))
+			break;
+
+		if (!skip || !string_list_has_string(skip, extra_refname))
+			return extra_refname;
+	}
+	return NULL;
+}
+
+int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	struct object_id oid;
+	int flag;
+
+	if (refs_resolve_ref_unsafe(refs, "HEAD", RESOLVE_REF_READING,
+				    &oid, &flag))
+		return fn("HEAD", &oid, flag, cb_data);
+
+	return 0;
+}
+
+int head_ref(each_ref_fn fn, void *cb_data)
+{
+	return refs_head_ref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+struct ref_iterator *refs_ref_iterator_begin(
+		struct ref_store *refs,
+		const char *prefix,
+		const char **exclude_patterns,
+		int trim,
+		enum do_for_each_ref_flags flags)
+{
+	struct ref_iterator *iter;
+
+	if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
+		static int ref_paranoia = -1;
+
+		if (ref_paranoia < 0)
+			ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 1);
+		if (ref_paranoia) {
+			flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+			flags |= DO_FOR_EACH_OMIT_DANGLING_SYMREFS;
+		}
+	}
+
+	iter = refs->be->iterator_begin(refs, prefix, exclude_patterns, flags);
+	/*
+	 * `iterator_begin()` already takes care of prefix, but we
+	 * might need to do some trimming:
+	 */
+	if (trim)
+		iter = prefix_ref_iterator_begin(iter, "", trim);
+
+	/* Sanity check for subclasses: */
+	if (!iter->ordered)
+		BUG("reference iterator is not ordered");
+
+	return iter;
+}
+
+/*
+ * Call fn for each reference in the specified submodule for which the
+ * refname begins with prefix. If trim is non-zero, then trim that
+ * many characters off the beginning of each refname before passing
+ * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
+ * include broken references in the iteration. If fn ever returns a
+ * non-zero value, stop the iteration and return that value;
+ * otherwise, return 0.
+ */
+static int do_for_each_repo_ref(struct repository *r, const char *prefix,
+				each_repo_ref_fn fn, int trim, int flags,
+				void *cb_data)
+{
+	struct ref_iterator *iter;
+	struct ref_store *refs = get_main_ref_store(r);
+
+	if (!refs)
+		return 0;
+
+	iter = refs_ref_iterator_begin(refs, prefix, NULL, trim, flags);
+
+	return do_for_each_repo_ref_iterator(r, iter, fn, cb_data);
+}
+
+struct do_for_each_ref_help {
+	each_ref_fn *fn;
+	void *cb_data;
+};
+
+static int do_for_each_ref_helper(struct repository *r UNUSED,
+				  const char *refname,
+				  const struct object_id *oid,
+				  int flags,
+				  void *cb_data)
+{
+	struct do_for_each_ref_help *hp = cb_data;
+
+	return hp->fn(refname, oid, flags, hp->cb_data);
+}
+
+static int do_for_each_ref(struct ref_store *refs, const char *prefix,
+			   const char **exclude_patterns,
+			   each_ref_fn fn, int trim,
+			   enum do_for_each_ref_flags flags, void *cb_data)
+{
+	struct ref_iterator *iter;
+	struct do_for_each_ref_help hp = { fn, cb_data };
+
+	if (!refs)
+		return 0;
+
+	iter = refs_ref_iterator_begin(refs, prefix, exclude_patterns, trim,
+				       flags);
+
+	return do_for_each_repo_ref_iterator(the_repository, iter,
+					do_for_each_ref_helper, &hp);
+}
+
+int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(refs, "", NULL, fn, 0, 0, cb_data);
+}
+
+int for_each_ref(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_ref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
+			 each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(refs, prefix, NULL, fn, strlen(prefix), 0, cb_data);
+}
+
+int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_ref_in(get_main_ref_store(the_repository), prefix, fn, cb_data);
+}
+
+int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(get_main_ref_store(the_repository),
+			       prefix, NULL, fn, 0, 0, cb_data);
+}
+
+int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
+			     const char **exclude_patterns,
+			     each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(refs, prefix, exclude_patterns, fn, 0, 0, cb_data);
+}
+
+int for_each_replace_ref(struct repository *r, each_repo_ref_fn fn, void *cb_data)
+{
+	const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;
+	return do_for_each_repo_ref(r, git_replace_ref_base, fn,
+				    strlen(git_replace_ref_base),
+				    DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
+}
+
+int for_each_namespaced_ref(const char **exclude_patterns,
+			    each_ref_fn fn, void *cb_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int ret;
+	strbuf_addf(&buf, "%srefs/", get_git_namespace());
+	ret = do_for_each_ref(get_main_ref_store(the_repository),
+			      buf.buf, exclude_patterns, fn, 0, 0, cb_data);
+	strbuf_release(&buf);
+	return ret;
+}
+
+int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(refs, "", NULL, fn, 0,
+			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
+}
+
+int for_each_rawref(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_rawref(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+static int qsort_strcmp(const void *va, const void *vb)
+{
+	const char *a = *(const char **)va;
+	const char *b = *(const char **)vb;
+
+	return strcmp(a, b);
+}
+
+static void find_longest_prefixes_1(struct string_list *out,
+				  struct strbuf *prefix,
+				  const char **patterns, size_t nr)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++) {
+		char c = patterns[i][prefix->len];
+		if (!c || is_glob_special(c)) {
+			string_list_append(out, prefix->buf);
+			return;
+		}
+	}
+
+	i = 0;
+	while (i < nr) {
+		size_t end;
+
+		/*
+		* Set "end" to the index of the element _after_ the last one
+		* in our group.
+		*/
+		for (end = i + 1; end < nr; end++) {
+			if (patterns[i][prefix->len] != patterns[end][prefix->len])
+				break;
+		}
+
+		strbuf_addch(prefix, patterns[i][prefix->len]);
+		find_longest_prefixes_1(out, prefix, patterns + i, end - i);
+		strbuf_setlen(prefix, prefix->len - 1);
+
+		i = end;
+	}
+}
+
+static void find_longest_prefixes(struct string_list *out,
+				  const char **patterns)
+{
+	struct strvec sorted = STRVEC_INIT;
+	struct strbuf prefix = STRBUF_INIT;
+
+	strvec_pushv(&sorted, patterns);
+	QSORT(sorted.v, sorted.nr, qsort_strcmp);
+
+	find_longest_prefixes_1(out, &prefix, sorted.v, sorted.nr);
+
+	strvec_clear(&sorted);
+	strbuf_release(&prefix);
+}
+
+int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
+				      const char *namespace,
+				      const char **patterns,
+				      const char **exclude_patterns,
+				      each_ref_fn fn, void *cb_data)
+{
+	struct string_list prefixes = STRING_LIST_INIT_DUP;
+	struct string_list_item *prefix;
+	struct strbuf buf = STRBUF_INIT;
+	int ret = 0, namespace_len;
+
+	find_longest_prefixes(&prefixes, patterns);
+
+	if (namespace)
+		strbuf_addstr(&buf, namespace);
+	namespace_len = buf.len;
+
+	for_each_string_list_item(prefix, &prefixes) {
+		strbuf_addstr(&buf, prefix->string);
+		ret = refs_for_each_fullref_in(ref_store, buf.buf,
+					       exclude_patterns, fn, cb_data);
+		if (ret)
+			break;
+		strbuf_setlen(&buf, namespace_len);
+	}
+
+	string_list_clear(&prefixes, 0);
+	strbuf_release(&buf);
+	return ret;
+}
+
+static int refs_read_special_head(struct ref_store *ref_store,
+				  const char *refname, struct object_id *oid,
+				  struct strbuf *referent, unsigned int *type,
+				  int *failure_errno)
+{
+	struct strbuf full_path = STRBUF_INIT;
+	struct strbuf content = STRBUF_INIT;
+	int result = -1;
+	strbuf_addf(&full_path, "%s/%s", ref_store->gitdir, refname);
+
+	if (strbuf_read_file(&content, full_path.buf, 0) < 0)
+		goto done;
+
+	result = parse_loose_ref_contents(content.buf, oid, referent, type,
+					  failure_errno);
+
+done:
+	strbuf_release(&full_path);
+	strbuf_release(&content);
+	return result;
+}
+
+int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
+		      struct object_id *oid, struct strbuf *referent,
+		      unsigned int *type, int *failure_errno)
+{
+	assert(failure_errno);
+	if (!strcmp(refname, "FETCH_HEAD") || !strcmp(refname, "MERGE_HEAD")) {
+		return refs_read_special_head(ref_store, refname, oid, referent,
+					      type, failure_errno);
+	}
+
+	return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,
+					   type, failure_errno);
+}
+
+int refs_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
+			   struct strbuf *referent)
+{
+	return ref_store->be->read_symbolic_ref(ref_store, refname, referent);
+}
+
+const char *refs_resolve_ref_unsafe(struct ref_store *refs,
+				    const char *refname,
+				    int resolve_flags,
+				    struct object_id *oid,
+				    int *flags)
+{
+	static struct strbuf sb_refname = STRBUF_INIT;
+	struct object_id unused_oid;
+	int unused_flags;
+	int symref_count;
+
+	if (!oid)
+		oid = &unused_oid;
+	if (!flags)
+		flags = &unused_flags;
+
+	*flags = 0;
+
+	if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+		if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+		    !refname_is_safe(refname))
+			return NULL;
+
+		/*
+		 * repo_dwim_ref() uses REF_ISBROKEN to distinguish between
+		 * missing refs and refs that were present but invalid,
+		 * to complain about the latter to stderr.
+		 *
+		 * We don't know whether the ref exists, so don't set
+		 * REF_ISBROKEN yet.
+		 */
+		*flags |= REF_BAD_NAME;
+	}
+
+	for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
+		unsigned int read_flags = 0;
+		int failure_errno;
+
+		if (refs_read_raw_ref(refs, refname, oid, &sb_refname,
+				      &read_flags, &failure_errno)) {
+			*flags |= read_flags;
+
+			/* In reading mode, refs must eventually resolve */
+			if (resolve_flags & RESOLVE_REF_READING)
+				return NULL;
+
+			/*
+			 * Otherwise a missing ref is OK. But the files backend
+			 * may show errors besides ENOENT if there are
+			 * similarly-named refs.
+			 */
+			if (failure_errno != ENOENT &&
+			    failure_errno != EISDIR &&
+			    failure_errno != ENOTDIR)
+				return NULL;
+
+			oidclr(oid);
+			if (*flags & REF_BAD_NAME)
+				*flags |= REF_ISBROKEN;
+			return refname;
+		}
+
+		*flags |= read_flags;
+
+		if (!(read_flags & REF_ISSYMREF)) {
+			if (*flags & REF_BAD_NAME) {
+				oidclr(oid);
+				*flags |= REF_ISBROKEN;
+			}
+			return refname;
+		}
+
+		refname = sb_refname.buf;
+		if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+			oidclr(oid);
+			return refname;
+		}
+		if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+			if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+			    !refname_is_safe(refname))
+				return NULL;
+
+			*flags |= REF_ISBROKEN | REF_BAD_NAME;
+		}
+	}
+
+	return NULL;
+}
+
+/* backend functions */
+int refs_init_db(struct strbuf *err)
+{
+	struct ref_store *refs = get_main_ref_store(the_repository);
+
+	return refs->be->init_db(refs, err);
+}
+
+const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
+			       struct object_id *oid, int *flags)
+{
+	return refs_resolve_ref_unsafe(get_main_ref_store(the_repository), refname,
+				       resolve_flags, oid, flags);
+}
+
+int resolve_gitlink_ref(const char *submodule, const char *refname,
+			struct object_id *oid)
+{
+	struct ref_store *refs;
+	int flags;
+
+	refs = get_submodule_ref_store(submodule);
+
+	if (!refs)
+		return -1;
+
+	if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags) ||
+	    is_null_oid(oid))
+		return -1;
+	return 0;
+}
+
+struct ref_store_hash_entry
+{
+	struct hashmap_entry ent;
+
+	struct ref_store *refs;
+
+	/* NUL-terminated identifier of the ref store: */
+	char name[FLEX_ARRAY];
+};
+
+static int ref_store_hash_cmp(const void *cmp_data UNUSED,
+			      const struct hashmap_entry *eptr,
+			      const struct hashmap_entry *entry_or_key,
+			      const void *keydata)
+{
+	const struct ref_store_hash_entry *e1, *e2;
+	const char *name;
+
+	e1 = container_of(eptr, const struct ref_store_hash_entry, ent);
+	e2 = container_of(entry_or_key, const struct ref_store_hash_entry, ent);
+	name = keydata ? keydata : e2->name;
+
+	return strcmp(e1->name, name);
+}
+
+static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
+		const char *name, struct ref_store *refs)
+{
+	struct ref_store_hash_entry *entry;
+
+	FLEX_ALLOC_STR(entry, name, name);
+	hashmap_entry_init(&entry->ent, strhash(name));
+	entry->refs = refs;
+	return entry;
+}
+
+/* A hashmap of ref_stores, stored by submodule name: */
+static struct hashmap submodule_ref_stores;
+
+/* A hashmap of ref_stores, stored by worktree id: */
+static struct hashmap worktree_ref_stores;
+
+/*
+ * Look up a ref store by name. If that ref_store hasn't been
+ * registered yet, return NULL.
+ */
+static struct ref_store *lookup_ref_store_map(struct hashmap *map,
+					      const char *name)
+{
+	struct ref_store_hash_entry *entry;
+	unsigned int hash;
+
+	if (!map->tablesize)
+		/* It's initialized on demand in register_ref_store(). */
+		return NULL;
+
+	hash = strhash(name);
+	entry = hashmap_get_entry_from_hash(map, hash, name,
+					struct ref_store_hash_entry, ent);
+	return entry ? entry->refs : NULL;
+}
+
+/*
+ * Create, record, and return a ref_store instance for the specified
+ * gitdir.
+ */
+static struct ref_store *ref_store_init(struct repository *repo,
+					const char *gitdir,
+					unsigned int flags)
+{
+	const char *be_name = "files";
+	struct ref_storage_be *be = find_ref_storage_backend(be_name);
+	struct ref_store *refs;
+
+	if (!be)
+		BUG("reference backend %s is unknown", be_name);
+
+	refs = be->init(repo, gitdir, flags);
+	return refs;
+}
+
+struct ref_store *get_main_ref_store(struct repository *r)
+{
+	if (r->refs_private)
+		return r->refs_private;
+
+	if (!r->gitdir)
+		BUG("attempting to get main_ref_store outside of repository");
+
+	r->refs_private = ref_store_init(r, r->gitdir, REF_STORE_ALL_CAPS);
+	r->refs_private = maybe_debug_wrap_ref_store(r->gitdir, r->refs_private);
+	return r->refs_private;
+}
+
+/*
+ * Associate a ref store with a name. It is a fatal error to call this
+ * function twice for the same name.
+ */
+static void register_ref_store_map(struct hashmap *map,
+				   const char *type,
+				   struct ref_store *refs,
+				   const char *name)
+{
+	struct ref_store_hash_entry *entry;
+
+	if (!map->tablesize)
+		hashmap_init(map, ref_store_hash_cmp, NULL, 0);
+
+	entry = alloc_ref_store_hash_entry(name, refs);
+	if (hashmap_put(map, &entry->ent))
+		BUG("%s ref_store '%s' initialized twice", type, name);
+}
+
+struct ref_store *get_submodule_ref_store(const char *submodule)
+{
+	struct strbuf submodule_sb = STRBUF_INIT;
+	struct ref_store *refs;
+	char *to_free = NULL;
+	size_t len;
+	struct repository *subrepo;
+
+	if (!submodule)
+		return NULL;
+
+	len = strlen(submodule);
+	while (len && is_dir_sep(submodule[len - 1]))
+		len--;
+	if (!len)
+		return NULL;
+
+	if (submodule[len])
+		/* We need to strip off one or more trailing slashes */
+		submodule = to_free = xmemdupz(submodule, len);
+
+	refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
+	if (refs)
+		goto done;
+
+	strbuf_addstr(&submodule_sb, submodule);
+	if (!is_nonbare_repository_dir(&submodule_sb))
+		goto done;
+
+	if (submodule_to_gitdir(&submodule_sb, submodule))
+		goto done;
+
+	subrepo = xmalloc(sizeof(*subrepo));
+	/*
+	 * NEEDSWORK: Make get_submodule_ref_store() work with arbitrary
+	 * superprojects other than the_repository. This probably should be
+	 * done by making it take a struct repository * parameter instead of a
+	 * submodule path.
+	 */
+	if (repo_submodule_init(subrepo, the_repository, submodule,
+				null_oid())) {
+		free(subrepo);
+		goto done;
+	}
+	refs = ref_store_init(subrepo, submodule_sb.buf,
+			      REF_STORE_READ | REF_STORE_ODB);
+	register_ref_store_map(&submodule_ref_stores, "submodule",
+			       refs, submodule);
+
+done:
+	strbuf_release(&submodule_sb);
+	free(to_free);
+
+	return refs;
+}
+
+struct ref_store *get_worktree_ref_store(const struct worktree *wt)
+{
+	struct ref_store *refs;
+	const char *id;
+
+	if (wt->is_current)
+		return get_main_ref_store(the_repository);
+
+	id = wt->id ? wt->id : "/";
+	refs = lookup_ref_store_map(&worktree_ref_stores, id);
+	if (refs)
+		return refs;
+
+	if (wt->id)
+		refs = ref_store_init(the_repository,
+				      git_common_path("worktrees/%s", wt->id),
+				      REF_STORE_ALL_CAPS);
+	else
+		refs = ref_store_init(the_repository,
+				      get_git_common_dir(),
+				      REF_STORE_ALL_CAPS);
+
+	if (refs)
+		register_ref_store_map(&worktree_ref_stores, "worktree",
+				       refs, id);
+	return refs;
+}
+
+void base_ref_store_init(struct ref_store *refs, struct repository *repo,
+			 const char *path, const struct ref_storage_be *be)
+{
+	refs->be = be;
+	refs->repo = repo;
+	refs->gitdir = xstrdup(path);
+}
+
+/* backend functions */
+int refs_pack_refs(struct ref_store *refs, struct pack_refs_opts *opts)
+{
+	return refs->be->pack_refs(refs, opts);
+}
+
+int peel_iterated_oid(const struct object_id *base, struct object_id *peeled)
+{
+	if (current_ref_iter &&
+	    (current_ref_iter->oid == base ||
+	     oideq(current_ref_iter->oid, base)))
+		return ref_iterator_peel(current_ref_iter, peeled);
+
+	return peel_object(base, peeled) ? -1 : 0;
+}
+
+int refs_create_symref(struct ref_store *refs,
+		       const char *ref_target,
+		       const char *refs_heads_master,
+		       const char *logmsg)
+{
+	char *msg;
+	int retval;
+
+	msg = normalize_reflog_message(logmsg);
+	retval = refs->be->create_symref(refs, ref_target, refs_heads_master,
+					 msg);
+	free(msg);
+	return retval;
+}
+
+int create_symref(const char *ref_target, const char *refs_heads_master,
+		  const char *logmsg)
+{
+	return refs_create_symref(get_main_ref_store(the_repository), ref_target,
+				  refs_heads_master, logmsg);
+}
+
+int ref_update_reject_duplicates(struct string_list *refnames,
+				 struct strbuf *err)
+{
+	size_t i, n = refnames->nr;
+
+	assert(err);
+
+	for (i = 1; i < n; i++) {
+		int cmp = strcmp(refnames->items[i - 1].string,
+				 refnames->items[i].string);
+
+		if (!cmp) {
+			strbuf_addf(err,
+				    _("multiple updates for ref '%s' not allowed"),
+				    refnames->items[i].string);
+			return 1;
+		} else if (cmp > 0) {
+			BUG("ref_update_reject_duplicates() received unsorted list");
+		}
+	}
+	return 0;
+}
+
+static int run_transaction_hook(struct ref_transaction *transaction,
+				const char *state)
+{
+	struct child_process proc = CHILD_PROCESS_INIT;
+	struct strbuf buf = STRBUF_INIT;
+	const char *hook;
+	int ret = 0, i;
+
+	hook = find_hook("reference-transaction");
+	if (!hook)
+		return ret;
+
+	strvec_pushl(&proc.args, hook, state, NULL);
+	proc.in = -1;
+	proc.stdout_to_stderr = 1;
+	proc.trace2_hook_name = "reference-transaction";
+
+	ret = start_command(&proc);
+	if (ret)
+		return ret;
+
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	for (i = 0; i < transaction->nr; i++) {
+		struct ref_update *update = transaction->updates[i];
+
+		strbuf_reset(&buf);
+		strbuf_addf(&buf, "%s %s %s\n",
+			    oid_to_hex(&update->old_oid),
+			    oid_to_hex(&update->new_oid),
+			    update->refname);
+
+		if (write_in_full(proc.in, buf.buf, buf.len) < 0) {
+			if (errno != EPIPE) {
+				/* Don't leak errno outside this API */
+				errno = 0;
+				ret = -1;
+			}
+			break;
+		}
+	}
+
+	close(proc.in);
+	sigchain_pop(SIGPIPE);
+	strbuf_release(&buf);
+
+	ret |= finish_command(&proc);
+	return ret;
+}
+
+int ref_transaction_prepare(struct ref_transaction *transaction,
+			    struct strbuf *err)
+{
+	struct ref_store *refs = transaction->ref_store;
+	int ret;
+
+	switch (transaction->state) {
+	case REF_TRANSACTION_OPEN:
+		/* Good. */
+		break;
+	case REF_TRANSACTION_PREPARED:
+		BUG("prepare called twice on reference transaction");
+		break;
+	case REF_TRANSACTION_CLOSED:
+		BUG("prepare called on a closed reference transaction");
+		break;
+	default:
+		BUG("unexpected reference transaction state");
+		break;
+	}
+
+	if (refs->repo->objects->odb->disable_ref_updates) {
+		strbuf_addstr(err,
+			      _("ref updates forbidden inside quarantine environment"));
+		return -1;
+	}
+
+	ret = refs->be->transaction_prepare(refs, transaction, err);
+	if (ret)
+		return ret;
+
+	ret = run_transaction_hook(transaction, "prepared");
+	if (ret) {
+		ref_transaction_abort(transaction, err);
+		die(_("ref updates aborted by hook"));
+	}
+
+	return 0;
+}
+
+int ref_transaction_abort(struct ref_transaction *transaction,
+			  struct strbuf *err)
+{
+	struct ref_store *refs = transaction->ref_store;
+	int ret = 0;
+
+	switch (transaction->state) {
+	case REF_TRANSACTION_OPEN:
+		/* No need to abort explicitly. */
+		break;
+	case REF_TRANSACTION_PREPARED:
+		ret = refs->be->transaction_abort(refs, transaction, err);
+		break;
+	case REF_TRANSACTION_CLOSED:
+		BUG("abort called on a closed reference transaction");
+		break;
+	default:
+		BUG("unexpected reference transaction state");
+		break;
+	}
+
+	run_transaction_hook(transaction, "aborted");
+
+	ref_transaction_free(transaction);
+	return ret;
+}
+
+int ref_transaction_commit(struct ref_transaction *transaction,
+			   struct strbuf *err)
+{
+	struct ref_store *refs = transaction->ref_store;
+	int ret;
+
+	switch (transaction->state) {
+	case REF_TRANSACTION_OPEN:
+		/* Need to prepare first. */
+		ret = ref_transaction_prepare(transaction, err);
+		if (ret)
+			return ret;
+		break;
+	case REF_TRANSACTION_PREPARED:
+		/* Fall through to finish. */
+		break;
+	case REF_TRANSACTION_CLOSED:
+		BUG("commit called on a closed reference transaction");
+		break;
+	default:
+		BUG("unexpected reference transaction state");
+		break;
+	}
+
+	ret = refs->be->transaction_finish(refs, transaction, err);
+	if (!ret)
+		run_transaction_hook(transaction, "committed");
+	return ret;
+}
+
+int refs_verify_refname_available(struct ref_store *refs,
+				  const char *refname,
+				  const struct string_list *extras,
+				  const struct string_list *skip,
+				  struct strbuf *err)
+{
+	const char *slash;
+	const char *extra_refname;
+	struct strbuf dirname = STRBUF_INIT;
+	struct strbuf referent = STRBUF_INIT;
+	struct object_id oid;
+	unsigned int type;
+	struct ref_iterator *iter;
+	int ok;
+	int ret = -1;
+
+	/*
+	 * For the sake of comments in this function, suppose that
+	 * refname is "refs/foo/bar".
+	 */
+
+	assert(err);
+
+	strbuf_grow(&dirname, strlen(refname) + 1);
+	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+		/*
+		 * Just saying "Is a directory" when we e.g. can't
+		 * lock some multi-level ref isn't very informative,
+		 * the user won't be told *what* is a directory, so
+		 * let's not use strerror() below.
+		 */
+		int ignore_errno;
+		/* Expand dirname to the new prefix, not including the trailing slash: */
+		strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
+
+		/*
+		 * We are still at a leading dir of the refname (e.g.,
+		 * "refs/foo"; if there is a reference with that name,
+		 * it is a conflict, *unless* it is in skip.
+		 */
+		if (skip && string_list_has_string(skip, dirname.buf))
+			continue;
+
+		if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent,
+				       &type, &ignore_errno)) {
+			strbuf_addf(err, _("'%s' exists; cannot create '%s'"),
+				    dirname.buf, refname);
+			goto cleanup;
+		}
+
+		if (extras && string_list_has_string(extras, dirname.buf)) {
+			strbuf_addf(err, _("cannot process '%s' and '%s' at the same time"),
+				    refname, dirname.buf);
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * We are at the leaf of our refname (e.g., "refs/foo/bar").
+	 * There is no point in searching for a reference with that
+	 * name, because a refname isn't considered to conflict with
+	 * itself. But we still need to check for references whose
+	 * names are in the "refs/foo/bar/" namespace, because they
+	 * *do* conflict.
+	 */
+	strbuf_addstr(&dirname, refname + dirname.len);
+	strbuf_addch(&dirname, '/');
+
+	iter = refs_ref_iterator_begin(refs, dirname.buf, NULL, 0,
+				       DO_FOR_EACH_INCLUDE_BROKEN);
+	while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
+		if (skip &&
+		    string_list_has_string(skip, iter->refname))
+			continue;
+
+		strbuf_addf(err, _("'%s' exists; cannot create '%s'"),
+			    iter->refname, refname);
+		ref_iterator_abort(iter);
+		goto cleanup;
+	}
+
+	if (ok != ITER_DONE)
+		BUG("error while iterating over references");
+
+	extra_refname = find_descendant_ref(dirname.buf, extras, skip);
+	if (extra_refname)
+		strbuf_addf(err, _("cannot process '%s' and '%s' at the same time"),
+			    refname, extra_refname);
+	else
+		ret = 0;
+
+cleanup:
+	strbuf_release(&referent);
+	strbuf_release(&dirname);
+	return ret;
+}
+
+int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	struct ref_iterator *iter;
+	struct do_for_each_ref_help hp = { fn, cb_data };
+
+	iter = refs->be->reflog_iterator_begin(refs);
+
+	return do_for_each_repo_ref_iterator(the_repository, iter,
+					     do_for_each_ref_helper, &hp);
+}
+
+int for_each_reflog(each_ref_fn fn, void *cb_data)
+{
+	return refs_for_each_reflog(get_main_ref_store(the_repository), fn, cb_data);
+}
+
+int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
+				     const char *refname,
+				     each_reflog_ent_fn fn,
+				     void *cb_data)
+{
+	return refs->be->for_each_reflog_ent_reverse(refs, refname,
+						     fn, cb_data);
+}
+
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
+				void *cb_data)
+{
+	return refs_for_each_reflog_ent_reverse(get_main_ref_store(the_repository),
+						refname, fn, cb_data);
+}
+
+int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
+			     each_reflog_ent_fn fn, void *cb_data)
+{
+	return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
+}
+
+int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
+			void *cb_data)
+{
+	return refs_for_each_reflog_ent(get_main_ref_store(the_repository), refname,
+					fn, cb_data);
+}
+
+int refs_reflog_exists(struct ref_store *refs, const char *refname)
+{
+	return refs->be->reflog_exists(refs, refname);
+}
+
+int reflog_exists(const char *refname)
+{
+	return refs_reflog_exists(get_main_ref_store(the_repository), refname);
+}
+
+int refs_create_reflog(struct ref_store *refs, const char *refname,
+		       struct strbuf *err)
+{
+	return refs->be->create_reflog(refs, refname, err);
+}
+
+int safe_create_reflog(const char *refname, struct strbuf *err)
+{
+	return refs_create_reflog(get_main_ref_store(the_repository), refname,
+				  err);
+}
+
+int refs_delete_reflog(struct ref_store *refs, const char *refname)
+{
+	return refs->be->delete_reflog(refs, refname);
+}
+
+int delete_reflog(const char *refname)
+{
+	return refs_delete_reflog(get_main_ref_store(the_repository), refname);
+}
+
+int refs_reflog_expire(struct ref_store *refs,
+		       const char *refname,
+		       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)
+{
+	return refs->be->reflog_expire(refs, refname, flags,
+				       prepare_fn, should_prune_fn,
+				       cleanup_fn, policy_cb_data);
+}
+
+int reflog_expire(const char *refname,
+		  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)
+{
+	return refs_reflog_expire(get_main_ref_store(the_repository),
+				  refname, flags,
+				  prepare_fn, should_prune_fn,
+				  cleanup_fn, policy_cb_data);
+}
+
+int initial_ref_transaction_commit(struct ref_transaction *transaction,
+				   struct strbuf *err)
+{
+	struct ref_store *refs = transaction->ref_store;
+
+	return refs->be->initial_transaction_commit(refs, transaction, err);
+}
+
+void ref_transaction_for_each_queued_update(struct ref_transaction *transaction,
+					    ref_transaction_for_each_queued_update_fn cb,
+					    void *cb_data)
+{
+	int i;
+
+	for (i = 0; i < transaction->nr; i++) {
+		struct ref_update *update = transaction->updates[i];
+
+		cb(update->refname,
+		   (update->flags & REF_HAVE_OLD) ? &update->old_oid : NULL,
+		   (update->flags & REF_HAVE_NEW) ? &update->new_oid : NULL,
+		   cb_data);
+	}
+}
+
+int refs_delete_refs(struct ref_store *refs, const char *logmsg,
+		     struct string_list *refnames, unsigned int flags)
+{
+	char *msg;
+	int retval;
+
+	msg = normalize_reflog_message(logmsg);
+	retval = refs->be->delete_refs(refs, msg, refnames, flags);
+	free(msg);
+	return retval;
+}
+
+int delete_refs(const char *msg, struct string_list *refnames,
+		unsigned int flags)
+{
+	return refs_delete_refs(get_main_ref_store(the_repository), msg, refnames, flags);
+}
+
+int refs_rename_ref(struct ref_store *refs, const char *oldref,
+		    const char *newref, const char *logmsg)
+{
+	char *msg;
+	int retval;
+
+	msg = normalize_reflog_message(logmsg);
+	retval = refs->be->rename_ref(refs, oldref, newref, msg);
+	free(msg);
+	return retval;
+}
+
+int rename_ref(const char *oldref, const char *newref, const char *logmsg)
+{
+	return refs_rename_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
+}
+
+int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
+		    const char *newref, const char *logmsg)
+{
+	char *msg;
+	int retval;
+
+	msg = normalize_reflog_message(logmsg);
+	retval = refs->be->copy_ref(refs, oldref, newref, msg);
+	free(msg);
+	return retval;
+}
+
+int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
+{
+	return refs_copy_existing_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
+}