date.c: abort if the system time cannot handle one of our timestamps
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index e7606716ddfff47b29f90e4d46cb2d59633cb455..6841bd9f7122c5a866b27e0e66c2c38da9d2990b 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -9,6 +9,7 @@
 #include "refs/refs-internal.h"
 #include "object.h"
 #include "tag.h"
+#include "submodule.h"
 
 /*
  * List of all available backends
@@ -170,11 +171,23 @@ int refname_is_safe(const char *refname)
        return 1;
 }
 
+char *refs_resolve_refdup(struct ref_store *refs,
+                         const char *refname, int resolve_flags,
+                         unsigned char *sha1, int *flags)
+{
+       const char *result;
+
+       result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
+                                        sha1, flags);
+       return xstrdup_or_null(result);
+}
+
 char *resolve_refdup(const char *refname, int resolve_flags,
                     unsigned char *sha1, int *flags)
 {
-       return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
-                                                 sha1, flags));
+       return refs_resolve_refdup(get_main_ref_store(),
+                                  refname, resolve_flags,
+                                  sha1, flags);
 }
 
 /* The argument to filter_refs */
@@ -184,13 +197,20 @@ struct ref_filter {
        void *cb_data;
 };
 
-int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
+int refs_read_ref_full(struct ref_store *refs, const char *refname,
+                      int resolve_flags, unsigned char *sha1, int *flags)
 {
-       if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
+       if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, sha1, flags))
                return 0;
        return -1;
 }
 
+int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
+{
+       return refs_read_ref_full(get_main_ref_store(), refname,
+                                 resolve_flags, sha1, flags);
+}
+
 int read_ref(const char *refname, unsigned char *sha1)
 {
        return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
@@ -285,34 +305,52 @@ void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_li
        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 for_each_ref_in("refs/tags/", fn, cb_data);
+       return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
 }
 
 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
+       return refs_for_each_tag_ref(get_submodule_ref_store(submodule),
+                                    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 for_each_ref_in("refs/heads/", fn, cb_data);
+       return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
 }
 
 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
+       return refs_for_each_branch_ref(get_submodule_ref_store(submodule),
+                                       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 for_each_ref_in("refs/remotes/", fn, cb_data);
+       return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
 }
 
 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
+       return refs_for_each_remote_ref(get_submodule_ref_store(submodule),
+                                       fn, cb_data);
 }
 
 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
@@ -366,11 +404,11 @@ int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 
 const char *prettify_refname(const char *name)
 {
-       return name + (
-               starts_with(name, "refs/heads/") ? 11 :
-               starts_with(name, "refs/tags/") ? 10 :
-               starts_with(name, "refs/remotes/") ? 13 :
-               0);
+       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[] = {
@@ -429,29 +467,31 @@ int expand_ref(const char *str, int len, unsigned char *sha1, 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++) {
-               char fullref[PATH_MAX];
                unsigned char sha1_from_ref[20];
                unsigned char *this_result;
                int flag;
 
                this_result = refs_found ? sha1_from_ref : sha1;
-               mksnpath(fullref, sizeof(fullref), *p, len, str);
-               r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
+               strbuf_reset(&fullref);
+               strbuf_addf(&fullref, *p, len, str);
+               r = resolve_ref_unsafe(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, "HEAD")) {
-                       warning("ignoring dangling symref %s.", fullref);
-               } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
-                       warning("ignoring broken ref %s.", fullref);
+               } 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;
 }
 
@@ -460,21 +500,22 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
        char *last_branch = substitute_branch_name(&str, &len);
        const char **p;
        int logs_found = 0;
+       struct strbuf path = STRBUF_INIT;
 
        *log = NULL;
        for (p = ref_rev_parse_rules; *p; p++) {
                unsigned char hash[20];
-               char path[PATH_MAX];
                const char *ref, *it;
 
-               mksnpath(path, sizeof(path), *p, len, str);
-               ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
+               strbuf_reset(&path);
+               strbuf_addf(&path, *p, len, str);
+               ref = resolve_ref_unsafe(path.buf, RESOLVE_REF_READING,
                                         hash, NULL);
                if (!ref)
                        continue;
-               if (reflog_exists(path))
-                       it = path;
-               else if (strcmp(ref, path) && reflog_exists(ref))
+               if (reflog_exists(path.buf))
+                       it = path.buf;
+               else if (strcmp(ref, path.buf) && reflog_exists(ref))
                        it = ref;
                else
                        continue;
@@ -485,6 +526,7 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
                if (!warn_ambiguous_refs)
                        break;
        }
+       strbuf_release(&path);
        free(last_branch);
        return logs_found;
 }
@@ -592,16 +634,20 @@ static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1
        return 0;
 }
 
-int delete_ref(const char *msg, const char *refname,
-              const unsigned char *old_sha1, unsigned int flags)
+int refs_delete_ref(struct ref_store *refs, const char *msg,
+                   const char *refname,
+                   const unsigned char *old_sha1,
+                   unsigned int flags)
 {
        struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
 
-       if (ref_type(refname) == REF_TYPE_PSEUDOREF)
+       if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
+               assert(refs == get_main_ref_store());
                return delete_pseudoref(refname, old_sha1);
+       }
 
-       transaction = ref_transaction_begin(&err);
+       transaction = ref_store_transaction_begin(refs, &err);
        if (!transaction ||
            ref_transaction_delete(transaction, refname, old_sha1,
                                   flags, msg, &err) ||
@@ -616,6 +662,13 @@ int delete_ref(const char *msg, const char *refname,
        return 0;
 }
 
+int delete_ref(const char *msg, const char *refname,
+              const unsigned char *old_sha1, unsigned int flags)
+{
+       return refs_delete_ref(get_main_ref_store(), msg, refname,
+                              old_sha1, flags);
+}
+
 int copy_reflog_msg(char *buf, const char *msg)
 {
        char *cp = buf;
@@ -659,7 +712,7 @@ int is_branch(const char *refname)
 
 struct read_ref_at_cb {
        const char *refname;
-       unsigned long at_time;
+       timestamp_t at_time;
        int cnt;
        int reccnt;
        unsigned char *sha1;
@@ -668,15 +721,15 @@ struct read_ref_at_cb {
        unsigned char osha1[20];
        unsigned char nsha1[20];
        int tz;
-       unsigned long date;
+       timestamp_t date;
        char **msg;
-       unsigned long *cutoff_time;
+       timestamp_t *cutoff_time;
        int *cutoff_tz;
        int *cutoff_cnt;
 };
 
 static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
-               const char *email, unsigned long timestamp, int tz,
+               const char *email, timestamp_t timestamp, int tz,
                const char *message, void *cb_data)
 {
        struct read_ref_at_cb *cb = cb_data;
@@ -723,7 +776,7 @@ static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
 }
 
 static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
-                                 const char *email, unsigned long timestamp,
+                                 const char *email, timestamp_t timestamp,
                                  int tz, const char *message, void *cb_data)
 {
        struct read_ref_at_cb *cb = cb_data;
@@ -743,9 +796,9 @@ static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid
        return 1;
 }
 
-int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
+int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
                unsigned char *sha1, char **msg,
-               unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
+               timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 {
        struct read_ref_at_cb cb;
 
@@ -775,11 +828,20 @@ int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time,
        return 1;
 }
 
-struct ref_transaction *ref_transaction_begin(struct strbuf *err)
+struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
+                                                   struct strbuf *err)
 {
+       struct ref_transaction *tr;
        assert(err);
 
-       return xcalloc(1, sizeof(struct ref_transaction));
+       tr = xcalloc(1, sizeof(struct ref_transaction));
+       tr->ref_store = refs;
+       return tr;
+}
+
+struct ref_transaction *ref_transaction_begin(struct strbuf *err)
+{
+       return ref_store_transaction_begin(get_main_ref_store(), err);
 }
 
 void ref_transaction_free(struct ref_transaction *transaction)
@@ -896,18 +958,20 @@ int update_ref_oid(const char *msg, const char *refname,
                old_oid ? old_oid->hash : NULL, flags, onerr);
 }
 
-int update_ref(const char *msg, const char *refname,
-              const unsigned char *new_sha1, const unsigned char *old_sha1,
-              unsigned int flags, enum action_on_err onerr)
+int refs_update_ref(struct ref_store *refs, const char *msg,
+                   const char *refname, const unsigned char *new_sha1,
+                   const unsigned char *old_sha1, unsigned int flags,
+                   enum action_on_err onerr)
 {
        struct ref_transaction *t = NULL;
        struct strbuf err = STRBUF_INIT;
        int ret = 0;
 
        if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
+               assert(refs == get_main_ref_store());
                ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
        } else {
-               t = ref_transaction_begin(&err);
+               t = ref_store_transaction_begin(refs, &err);
                if (!t ||
                    ref_transaction_update(t, refname, new_sha1, old_sha1,
                                           flags, msg, &err) ||
@@ -938,12 +1002,22 @@ int update_ref(const char *msg, const char *refname,
        return 0;
 }
 
+int update_ref(const char *msg, const char *refname,
+              const unsigned char *new_sha1,
+              const unsigned char *old_sha1,
+              unsigned int flags, enum action_on_err onerr)
+{
+       return refs_update_ref(get_main_ref_store(), msg, refname, new_sha1,
+                              old_sha1, flags, onerr);
+}
+
 char *shorten_unambiguous_ref(const char *refname, int strict)
 {
        int i;
        static char **scanf_fmts;
        static int nr_rules;
        char *short_name;
+       struct strbuf resolved_buf = STRBUF_INIT;
 
        if (!nr_rules) {
                /*
@@ -1002,7 +1076,6 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
                 */
                for (j = 0; j < rules_to_fail; j++) {
                        const char *rule = ref_rev_parse_rules[j];
-                       char refname[PATH_MAX];
 
                        /* skip matched rule */
                        if (i == j)
@@ -1013,9 +1086,10 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
                         * (with this previous rule) to a valid ref
                         * read_ref() returns 0 on success
                         */
-                       mksnpath(refname, sizeof(refname),
-                                rule, short_name_len, short_name);
-                       if (ref_exists(refname))
+                       strbuf_reset(&resolved_buf);
+                       strbuf_addf(&resolved_buf, rule,
+                                   short_name_len, short_name);
+                       if (ref_exists(resolved_buf.buf))
                                break;
                }
 
@@ -1023,10 +1097,13 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
                 * short name is non-ambiguous if all previous rules
                 * haven't resolved to a valid ref
                 */
-               if (j == rules_to_fail)
+               if (j == rules_to_fail) {
+                       strbuf_release(&resolved_buf);
                        return short_name;
+               }
        }
 
+       strbuf_release(&resolved_buf);
        free(short_name);
        return xstrdup(refname);
 }
@@ -1119,14 +1196,17 @@ const char *find_descendant_ref(const char *dirname,
        return NULL;
 }
 
-int rename_ref_available(const char *old_refname, const char *new_refname)
+int refs_rename_ref_available(struct ref_store *refs,
+                             const char *old_refname,
+                             const char *new_refname)
 {
        struct string_list skip = STRING_LIST_INIT_NODUP;
        struct strbuf err = STRBUF_INIT;
        int ok;
 
        string_list_insert(&skip, old_refname);
-       ok = !verify_refname_available(new_refname, NULL, &skip, &err);
+       ok = !refs_verify_refname_available(refs, new_refname,
+                                           NULL, &skip, &err);
        if (!ok)
                error("%s", err.buf);
 
@@ -1167,10 +1247,9 @@ int head_ref(each_ref_fn fn, void *cb_data)
  * non-zero value, stop the iteration and return that value;
  * otherwise, return 0.
  */
-static int do_for_each_ref(const char *submodule, const char *prefix,
+static int do_for_each_ref(struct ref_store *refs, const char *prefix,
                           each_ref_fn fn, int trim, int flags, void *cb_data)
 {
-       struct ref_store *refs = get_ref_store(submodule);
        struct ref_iterator *iter;
 
        if (!refs)
@@ -1182,19 +1261,30 @@ static int do_for_each_ref(const char *submodule, const char *prefix,
        return do_for_each_ref_iterator(iter, fn, cb_data);
 }
 
+int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
+}
+
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
+       return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
 }
 
 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
+       return refs_for_each_ref(get_submodule_ref_store(submodule), 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, fn, strlen(prefix), 0, cb_data);
 }
 
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
+       return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
 }
 
 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
@@ -1203,19 +1293,23 @@ int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsig
 
        if (broken)
                flag = DO_FOR_EACH_INCLUDE_BROKEN;
-       return do_for_each_ref(NULL, prefix, fn, 0, flag, cb_data);
+       return do_for_each_ref(get_main_ref_store(),
+                              prefix, fn, 0, flag, cb_data);
 }
 
 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
-               each_ref_fn fn, void *cb_data)
+                             each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
+       return refs_for_each_ref_in(get_submodule_ref_store(submodule),
+                                   prefix, fn, cb_data);
 }
 
 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, git_replace_ref_base, fn,
-                              strlen(git_replace_ref_base), 0, cb_data);
+       return do_for_each_ref(get_main_ref_store(),
+                              git_replace_ref_base, fn,
+                              strlen(git_replace_ref_base),
+                              0, cb_data);
 }
 
 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
@@ -1223,19 +1317,25 @@ int for_each_namespaced_ref(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(NULL, buf.buf, fn, 0, 0, cb_data);
+       ret = do_for_each_ref(get_main_ref_store(),
+                             buf.buf, fn, 0, 0, cb_data);
        strbuf_release(&buf);
        return ret;
 }
 
-int for_each_rawref(each_ref_fn fn, void *cb_data)
+int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, "", fn, 0,
+       return do_for_each_ref(refs, "", 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(), fn, cb_data);
+}
+
 /* This function needs to return a meaningful errno on failure */
-const char *resolve_ref_recursively(struct ref_store *refs,
+const char *refs_resolve_ref_unsafe(struct ref_store *refs,
                                    const char *refname,
                                    int resolve_flags,
                                    unsigned char *sha1, int *flags)
@@ -1314,7 +1414,7 @@ const char *resolve_ref_recursively(struct ref_store *refs,
 /* backend functions */
 int refs_init_db(struct strbuf *err)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       struct ref_store *refs = get_main_ref_store();
 
        return refs->be->init_db(refs, err);
 }
@@ -1322,7 +1422,7 @@ int refs_init_db(struct strbuf *err)
 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
                               unsigned char *sha1, int *flags)
 {
-       return resolve_ref_recursively(get_ref_store(NULL), refname,
+       return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
                                       resolve_flags, sha1, flags);
 }
 
@@ -1343,16 +1443,16 @@ int resolve_gitlink_ref(const char *submodule, const char *refname,
                /* We need to strip off one or more trailing slashes */
                char *stripped = xmemdupz(submodule, len);
 
-               refs = get_ref_store(stripped);
+               refs = get_submodule_ref_store(stripped);
                free(stripped);
        } else {
-               refs = get_ref_store(submodule);
+               refs = get_submodule_ref_store(submodule);
        }
 
        if (!refs)
                return -1;
 
-       if (!resolve_ref_recursively(refs, refname, 0, sha1, &flags) ||
+       if (!refs_resolve_ref_unsafe(refs, refname, 0, sha1, &flags) ||
            is_null_sha1(sha1))
                return -1;
        return 0;
@@ -1395,17 +1495,13 @@ static struct ref_store *main_ref_store;
 static struct hashmap submodule_ref_stores;
 
 /*
- * Return the ref_store instance for the specified submodule (or the
- * main repository if submodule is NULL). If that ref_store hasn't
- * been initialized yet, return NULL.
+ * Return the ref_store instance for the specified submodule. If that
+ * ref_store hasn't been initialized yet, return NULL.
  */
-static struct ref_store *lookup_ref_store(const char *submodule)
+static struct ref_store *lookup_submodule_ref_store(const char *submodule)
 {
        struct submodule_hash_entry *entry;
 
-       if (!submodule)
-               return main_ref_store;
-
        if (!submodule_ref_stores.tablesize)
                /* It's initialized on demand in register_ref_store(). */
                return NULL;
@@ -1415,34 +1511,12 @@ static struct ref_store *lookup_ref_store(const char *submodule)
        return entry ? entry->refs : NULL;
 }
 
-/*
- * Register the specified ref_store to be the one that should be used
- * for submodule (or the main repository if submodule is NULL). It is
- * a fatal error to call this function twice for the same submodule.
- */
-static void register_ref_store(struct ref_store *refs, const char *submodule)
-{
-       if (!submodule) {
-               if (main_ref_store)
-                       die("BUG: main_ref_store initialized twice");
-
-               main_ref_store = refs;
-       } else {
-               if (!submodule_ref_stores.tablesize)
-                       hashmap_init(&submodule_ref_stores, submodule_hash_cmp, 0);
-
-               if (hashmap_put(&submodule_ref_stores,
-                               alloc_submodule_hash_entry(submodule, refs)))
-                       die("BUG: ref_store for submodule '%s' initialized twice",
-                           submodule);
-       }
-}
-
 /*
  * Create, record, and return a ref_store instance for the specified
- * submodule (or the main repository if submodule is NULL).
+ * gitdir.
  */
-static struct ref_store *ref_store_init(const char *submodule)
+static struct ref_store *ref_store_init(const char *gitdir,
+                                       unsigned int flags)
 {
        const char *be_name = "files";
        struct ref_storage_be *be = find_ref_storage_backend(be_name);
@@ -1451,33 +1525,76 @@ static struct ref_store *ref_store_init(const char *submodule)
        if (!be)
                die("BUG: reference backend %s is unknown", be_name);
 
-       refs = be->init(submodule);
-       register_ref_store(refs, submodule);
+       refs = be->init(gitdir, flags);
        return refs;
 }
 
-struct ref_store *get_ref_store(const char *submodule)
+struct ref_store *get_main_ref_store(void)
+{
+       if (main_ref_store)
+               return main_ref_store;
+
+       main_ref_store = ref_store_init(get_git_dir(),
+                                       (REF_STORE_READ |
+                                        REF_STORE_WRITE |
+                                        REF_STORE_ODB |
+                                        REF_STORE_MAIN));
+       return main_ref_store;
+}
+
+/*
+ * Register the specified ref_store to be the one that should be used
+ * for submodule. It is a fatal error to call this function twice for
+ * the same submodule.
+ */
+static void register_submodule_ref_store(struct ref_store *refs,
+                                        const char *submodule)
 {
+       if (!submodule_ref_stores.tablesize)
+               hashmap_init(&submodule_ref_stores, submodule_hash_cmp, 0);
+
+       if (hashmap_put(&submodule_ref_stores,
+                       alloc_submodule_hash_entry(submodule, refs)))
+               die("BUG: ref_store for submodule '%s' initialized twice",
+                   submodule);
+}
+
+struct ref_store *get_submodule_ref_store(const char *submodule)
+{
+       struct strbuf submodule_sb = STRBUF_INIT;
        struct ref_store *refs;
+       int ret;
 
        if (!submodule || !*submodule) {
-               refs = lookup_ref_store(NULL);
+               /*
+                * FIXME: This case is ideally not allowed. But that
+                * can't happen until we clean up all the callers.
+                */
+               return get_main_ref_store();
+       }
 
-               if (!refs)
-                       refs = ref_store_init(NULL);
-       } else {
-               refs = lookup_ref_store(submodule);
+       refs = lookup_submodule_ref_store(submodule);
+       if (refs)
+               return refs;
 
-               if (!refs) {
-                       struct strbuf submodule_sb = STRBUF_INIT;
+       strbuf_addstr(&submodule_sb, submodule);
+       ret = is_nonbare_repository_dir(&submodule_sb);
+       strbuf_release(&submodule_sb);
+       if (!ret)
+               return NULL;
 
-                       strbuf_addstr(&submodule_sb, submodule);
-                       if (is_nonbare_repository_dir(&submodule_sb))
-                               refs = ref_store_init(submodule);
-                       strbuf_release(&submodule_sb);
-               }
+       ret = submodule_to_gitdir(&submodule_sb, submodule);
+       if (ret) {
+               strbuf_release(&submodule_sb);
+               return NULL;
        }
 
+       /* assume that add_submodule_odb() has been called */
+       refs = ref_store_init(submodule_sb.buf,
+                             REF_STORE_READ | REF_STORE_ODB);
+       register_submodule_ref_store(refs, submodule);
+
+       strbuf_release(&submodule_sb);
        return refs;
 }
 
@@ -1488,50 +1605,58 @@ void base_ref_store_init(struct ref_store *refs,
 }
 
 /* backend functions */
-int pack_refs(unsigned int flags)
+int refs_pack_refs(struct ref_store *refs, unsigned int flags)
 {
-       struct ref_store *refs = get_ref_store(NULL);
-
        return refs->be->pack_refs(refs, flags);
 }
 
+int refs_peel_ref(struct ref_store *refs, const char *refname,
+                 unsigned char *sha1)
+{
+       return refs->be->peel_ref(refs, refname, sha1);
+}
+
 int peel_ref(const char *refname, unsigned char *sha1)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_peel_ref(get_main_ref_store(), refname, sha1);
+}
 
-       return refs->be->peel_ref(refs, refname, sha1);
+int refs_create_symref(struct ref_store *refs,
+                      const char *ref_target,
+                      const char *refs_heads_master,
+                      const char *logmsg)
+{
+       return refs->be->create_symref(refs, ref_target,
+                                      refs_heads_master,
+                                      logmsg);
 }
 
 int create_symref(const char *ref_target, const char *refs_heads_master,
                  const char *logmsg)
 {
-       struct ref_store *refs = get_ref_store(NULL);
-
-       return refs->be->create_symref(refs, ref_target, refs_heads_master,
-                                      logmsg);
+       return refs_create_symref(get_main_ref_store(), ref_target,
+                                 refs_heads_master, logmsg);
 }
 
 int ref_transaction_commit(struct ref_transaction *transaction,
                           struct strbuf *err)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       struct ref_store *refs = transaction->ref_store;
 
        return refs->be->transaction_commit(refs, transaction, err);
 }
 
-int verify_refname_available(const char *refname,
-                            const struct string_list *extra,
-                            const struct string_list *skip,
-                            struct strbuf *err)
+int refs_verify_refname_available(struct ref_store *refs,
+                                 const char *refname,
+                                 const struct string_list *extra,
+                                 const struct string_list *skip,
+                                 struct strbuf *err)
 {
-       struct ref_store *refs = get_ref_store(NULL);
-
        return refs->be->verify_refname_available(refs, refname, extra, skip, err);
 }
 
-int for_each_reflog(each_ref_fn fn, void *cb_data)
+int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 {
-       struct ref_store *refs = get_ref_store(NULL);
        struct ref_iterator *iter;
 
        iter = refs->be->reflog_iterator_begin(refs);
@@ -1539,43 +1664,84 @@ int for_each_reflog(each_ref_fn fn, void *cb_data)
        return do_for_each_ref_iterator(iter, fn, cb_data);
 }
 
-int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
-                               void *cb_data)
+int for_each_reflog(each_ref_fn fn, void *cb_data)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_for_each_reflog(get_main_ref_store(), 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(),
+                                               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)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_for_each_reflog_ent(get_main_ref_store(), refname,
+                                       fn, cb_data);
+}
 
-       return refs->be->for_each_reflog_ent(refs, 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)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_reflog_exists(get_main_ref_store(), refname);
+}
 
-       return refs->be->reflog_exists(refs, refname);
+int refs_create_reflog(struct ref_store *refs, const char *refname,
+                      int force_create, struct strbuf *err)
+{
+       return refs->be->create_reflog(refs, refname, force_create, err);
 }
 
 int safe_create_reflog(const char *refname, int force_create,
                       struct strbuf *err)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_create_reflog(get_main_ref_store(), refname,
+                                 force_create, err);
+}
 
-       return refs->be->create_reflog(refs, refname, force_create, 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)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_delete_reflog(get_main_ref_store(), refname);
+}
 
-       return refs->be->delete_reflog(refs, refname);
+int refs_reflog_expire(struct ref_store *refs,
+                      const char *refname, const unsigned char *sha1,
+                      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, sha1, flags,
+                                      prepare_fn, should_prune_fn,
+                                      cleanup_fn, policy_cb_data);
 }
 
 int reflog_expire(const char *refname, const unsigned char *sha1,
@@ -1585,31 +1751,38 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
                  reflog_expiry_cleanup_fn cleanup_fn,
                  void *policy_cb_data)
 {
-       struct ref_store *refs = get_ref_store(NULL);
-
-       return refs->be->reflog_expire(refs, refname, sha1, flags,
-                                      prepare_fn, should_prune_fn,
-                                      cleanup_fn, policy_cb_data);
+       return refs_reflog_expire(get_main_ref_store(),
+                                 refname, sha1, 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 = get_ref_store(NULL);
+       struct ref_store *refs = transaction->ref_store;
 
        return refs->be->initial_transaction_commit(refs, transaction, err);
 }
 
-int delete_refs(struct string_list *refnames, unsigned int flags)
+int refs_delete_refs(struct ref_store *refs, struct string_list *refnames,
+                    unsigned int flags)
 {
-       struct ref_store *refs = get_ref_store(NULL);
-
        return refs->be->delete_refs(refs, refnames, flags);
 }
 
-int rename_ref(const char *oldref, const char *newref, const char *logmsg)
+int delete_refs(struct string_list *refnames, unsigned int flags)
 {
-       struct ref_store *refs = get_ref_store(NULL);
+       return refs_delete_refs(get_main_ref_store(), refnames, flags);
+}
 
+int refs_rename_ref(struct ref_store *refs, const char *oldref,
+                   const char *newref, const char *logmsg)
+{
        return refs->be->rename_ref(refs, oldref, newref, logmsg);
 }
+
+int rename_ref(const char *oldref, const char *newref, const char *logmsg)
+{
+       return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
+}