Makefile: under "make dist", include the sha1collisiondetection submodule
[gitweb.git] / refs / files-backend.c
index a7cc65d0dee2dc5e8d3af6e447fc337e5958930f..f75d960e1982a2db5dc8828c6f1b10ffe64fda48 100644 (file)
 #include "../object.h"
 #include "../dir.h"
 
+/*
+ * This backend uses the following flags in `ref_update::flags` for
+ * internal bookkeeping purposes. Their numerical values must not
+ * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW,
+ * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in
+ * `ref_update::flags`.
+ */
+
+/*
+ * Used as a flag in ref_update::flags when a loose ref is being
+ * pruned. This flag must only be used when REF_NO_DEREF is set.
+ */
+#define REF_IS_PRUNING (1 << 4)
+
+/*
+ * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
+ * refs (i.e., because the reference is about to be deleted anyway).
+ */
+#define REF_DELETING (1 << 5)
+
+/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT (1 << 6)
+
+/*
+ * Used as a flag in ref_update::flags when we want to log a ref
+ * update but not actually perform it.  This is used when a symbolic
+ * ref update is split up.
+ */
+#define REF_LOG_ONLY (1 << 7)
+
+/*
+ * Used as a flag in ref_update::flags when the ref_update was via an
+ * update to HEAD.
+ */
+#define REF_UPDATE_VIA_HEAD (1 << 8)
+
+/*
+ * Used as a flag in ref_update::flags when the loose reference has
+ * been deleted.
+ */
+#define REF_DELETED_LOOSE (1 << 9)
+
 struct ref_lock {
        char *ref_name;
        struct lock_file lk;
@@ -189,13 +234,13 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
                        if (!refs_resolve_ref_unsafe(&refs->base,
                                                     refname.buf,
                                                     RESOLVE_REF_READING,
-                                                    oid.hash, &flag)) {
+                                                    &oid, &flag)) {
                                oidclr(&oid);
                                flag |= REF_ISBROKEN;
                        } else if (is_null_oid(&oid)) {
                                /*
                                 * It is so astronomically unlikely
-                                * that NULL_SHA1 is the SHA-1 of an
+                                * that null_oid is the OID of an
                                 * actual object that we consider its
                                 * appearance in a loose reference
                                 * file to be repo corruption
@@ -261,7 +306,7 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
 }
 
 static int files_read_raw_ref(struct ref_store *ref_store,
-                             const char *refname, unsigned char *sha1,
+                             const char *refname, struct object_id *oid,
                              struct strbuf *referent, unsigned int *type)
 {
        struct files_ref_store *refs =
@@ -270,6 +315,7 @@ static int files_read_raw_ref(struct ref_store *ref_store,
        struct strbuf sb_path = STRBUF_INIT;
        const char *path;
        const char *buf;
+       const char *p;
        struct stat st;
        int fd;
        int ret = -1;
@@ -304,7 +350,7 @@ static int files_read_raw_ref(struct ref_store *ref_store,
                if (errno != ENOENT)
                        goto out;
                if (refs_read_raw_ref(refs->packed_ref_store, refname,
-                                     sha1, referent, type)) {
+                                     oid, referent, type)) {
                        errno = ENOENT;
                        goto out;
                }
@@ -344,7 +390,7 @@ static int files_read_raw_ref(struct ref_store *ref_store,
                 * packed ref:
                 */
                if (refs_read_raw_ref(refs->packed_ref_store, refname,
-                                     sha1, referent, type)) {
+                                     oid, referent, type)) {
                        errno = EISDIR;
                        goto out;
                }
@@ -390,8 +436,8 @@ static int files_read_raw_ref(struct ref_store *ref_store,
         * Please note that FETCH_HEAD has additional
         * data after the sha.
         */
-       if (get_sha1_hex(buf, sha1) ||
-           (buf[40] != '\0' && !isspace(buf[40]))) {
+       if (parse_oid_hex(buf, oid, &p) ||
+           (*p != '\0' && !isspace(*p))) {
                *type |= REF_ISBROKEN;
                errno = EINVAL;
                goto out;
@@ -427,7 +473,7 @@ static void unlock_ref(struct ref_lock *lock)
  * are passed to refs_verify_refname_available() for this check.
  *
  * If mustexist is not set and the reference is not found or is
- * broken, lock the reference anyway but clear sha1.
+ * broken, lock the reference anyway but clear old_oid.
  *
  * Return 0 on success. On failure, write an error message to err and
  * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
@@ -545,7 +591,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
         */
 
        if (files_read_raw_ref(&refs->base, refname,
-                              lock->old_oid.hash, referent, type)) {
+                              &lock->old_oid, referent, type)) {
                if (errno == ENOENT) {
                        if (mustexist) {
                                /* Garden variety missing reference. */
@@ -641,43 +687,6 @@ static int lock_raw_ref(struct files_ref_store *refs,
        return ret;
 }
 
-static int files_peel_ref(struct ref_store *ref_store,
-                         const char *refname, unsigned char *sha1)
-{
-       struct files_ref_store *refs =
-               files_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
-                              "peel_ref");
-       int flag;
-       unsigned char base[20];
-
-       if (current_ref_iter && current_ref_iter->refname == refname) {
-               struct object_id peeled;
-
-               if (ref_iterator_peel(current_ref_iter, &peeled))
-                       return -1;
-               hashcpy(sha1, peeled.hash);
-               return 0;
-       }
-
-       if (refs_read_ref_full(ref_store, refname,
-                              RESOLVE_REF_READING, base, &flag))
-               return -1;
-
-       /*
-        * If the reference is packed, read its ref_entry from the
-        * cache in the hope that we already know its peeled value.
-        * We only try this optimization on packed references because
-        * (a) forcing the filling of the loose reference cache could
-        * be expensive and (b) loose references anyway usually do not
-        * have REF_KNOWS_PEELED.
-        */
-       if (flag & REF_ISPACKED &&
-           !refs_peel_ref(refs->packed_ref_store, refname, sha1))
-               return 0;
-
-       return peel_object(base, sha1);
-}
-
 struct files_ref_iterator {
        struct ref_iterator base;
 
@@ -748,7 +757,7 @@ static struct ref_iterator *files_ref_iterator_begin(
                const char *prefix, unsigned int flags)
 {
        struct files_ref_store *refs;
-       struct ref_iterator *loose_iter, *packed_iter;
+       struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
        struct files_ref_iterator *iter;
        struct ref_iterator *ref_iterator;
        unsigned int required_flags = REF_STORE_READ;
@@ -758,10 +767,6 @@ static struct ref_iterator *files_ref_iterator_begin(
 
        refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
 
-       iter = xcalloc(1, sizeof(*iter));
-       ref_iterator = &iter->base;
-       base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
-
        /*
         * We must make sure that all loose refs are read before
         * accessing the packed-refs file; this avoids a race
@@ -797,28 +802,34 @@ static struct ref_iterator *files_ref_iterator_begin(
                        refs->packed_ref_store, prefix, 0,
                        DO_FOR_EACH_INCLUDE_BROKEN);
 
-       iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
+       overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
+
+       iter = xcalloc(1, sizeof(*iter));
+       ref_iterator = &iter->base;
+       base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
+                              overlay_iter->ordered);
+       iter->iter0 = overlay_iter;
        iter->flags = flags;
 
        return ref_iterator;
 }
 
 /*
- * Verify that the reference locked by lock has the value old_sha1.
- * Fail if the reference doesn't exist and mustexist is set. Return 0
- * on success. On error, write an error message to err, set errno, and
- * return a negative value.
+ * Verify that the reference locked by lock has the value old_oid
+ * (unless it is NULL).  Fail if the reference doesn't exist and
+ * mustexist is set. Return 0 on success. On error, write an error
+ * message to err, set errno, and return a negative value.
  */
 static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
-                      const unsigned char *old_sha1, int mustexist,
+                      const struct object_id *old_oid, int mustexist,
                       struct strbuf *err)
 {
        assert(err);
 
        if (refs_read_ref_full(ref_store, lock->ref_name,
                               mustexist ? RESOLVE_REF_READING : 0,
-                              lock->old_oid.hash, NULL)) {
-               if (old_sha1) {
+                              &lock->old_oid, NULL)) {
+               if (old_oid) {
                        int save_errno = errno;
                        strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
                        errno = save_errno;
@@ -828,11 +839,11 @@ static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
                        return 0;
                }
        }
-       if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
+       if (old_oid && oidcmp(&lock->old_oid, old_oid)) {
                strbuf_addf(err, "ref '%s' is at %s but expected %s",
                            lock->ref_name,
                            oid_to_hex(&lock->old_oid),
-                           sha1_to_hex(old_sha1));
+                           oid_to_hex(old_oid));
                errno = EBUSY;
                return -1;
        }
@@ -862,22 +873,22 @@ static int create_reflock(const char *path, void *cb)
  * Locks a ref returning the lock on success and NULL on failure.
  * On failure errno is set to something meaningful.
  */
-static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
-                                           const char *refname,
-                                           const unsigned char *old_sha1,
-                                           const struct string_list *extras,
-                                           const struct string_list *skip,
-                                           unsigned int flags, int *type,
-                                           struct strbuf *err)
+static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
+                                          const char *refname,
+                                          const struct object_id *old_oid,
+                                          const struct string_list *extras,
+                                          const struct string_list *skip,
+                                          unsigned int flags, int *type,
+                                          struct strbuf *err)
 {
        struct strbuf ref_file = STRBUF_INIT;
        struct ref_lock *lock;
        int last_errno = 0;
-       int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
+       int mustexist = (old_oid && !is_null_oid(old_oid));
        int resolve_flags = RESOLVE_REF_NO_RECURSE;
        int resolved;
 
-       files_assert_main_repository(refs, "lock_ref_sha1_basic");
+       files_assert_main_repository(refs, "lock_ref_oid_basic");
        assert(err);
 
        lock = xcalloc(1, sizeof(struct ref_lock));
@@ -890,7 +901,7 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
        files_ref_path(refs, &ref_file, refname);
        resolved = !!refs_resolve_ref_unsafe(&refs->base,
                                             refname, resolve_flags,
-                                            lock->old_oid.hash, type);
+                                            &lock->old_oid, type);
        if (!resolved && errno == EISDIR) {
                /*
                 * we are trying to lock foo but we used to
@@ -909,7 +920,7 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
                }
                resolved = !!refs_resolve_ref_unsafe(&refs->base,
                                                     refname, resolve_flags,
-                                                    lock->old_oid.hash, type);
+                                                    &lock->old_oid, type);
        }
        if (!resolved) {
                last_errno = errno;
@@ -943,7 +954,7 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
                goto error_return;
        }
 
-       if (verify_lock(&refs->base, lock, old_sha1, mustexist, err)) {
+       if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) {
                last_errno = errno;
                goto error_return;
        }
@@ -961,7 +972,7 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 
 struct ref_to_prune {
        struct ref_to_prune *next;
-       unsigned char sha1[20];
+       struct object_id oid;
        char name[FLEX_ARRAY];
 };
 
@@ -1023,29 +1034,42 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
 {
        struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
+       int ret = -1;
 
        if (check_refname_format(r->name, 0))
                return;
 
        transaction = ref_store_transaction_begin(&refs->base, &err);
-       if (!transaction ||
-           ref_transaction_delete(transaction, r->name, r->sha1,
-                                  REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
-           ref_transaction_commit(transaction, &err)) {
-               ref_transaction_free(transaction);
+       if (!transaction)
+               goto cleanup;
+       ref_transaction_add_update(
+                       transaction, r->name,
+                       REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
+                       &null_oid, &r->oid, NULL);
+       if (ref_transaction_commit(transaction, &err))
+               goto cleanup;
+
+       ret = 0;
+
+cleanup:
+       if (ret)
                error("%s", err.buf);
-               strbuf_release(&err);
-               return;
-       }
-       ref_transaction_free(transaction);
        strbuf_release(&err);
+       ref_transaction_free(transaction);
+       return;
 }
 
-static void prune_refs(struct files_ref_store *refs, struct ref_to_prune *r)
+/*
+ * Prune the loose versions of the references in the linked list
+ * `*refs_to_prune`, freeing the entries in the list as we go.
+ */
+static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
 {
-       while (r) {
+       while (*refs_to_prune) {
+               struct ref_to_prune *r = *refs_to_prune;
+               *refs_to_prune = r->next;
                prune_ref(refs, r);
-               r = r->next;
+               free(r);
        }
 }
 
@@ -1084,6 +1108,11 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
        int ok;
        struct ref_to_prune *refs_to_prune = NULL;
        struct strbuf err = STRBUF_INIT;
+       struct ref_transaction *transaction;
+
+       transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
+       if (!transaction)
+               return -1;
 
        packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
 
@@ -1099,18 +1128,20 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
                        continue;
 
                /*
-                * Create an entry in the packed-refs cache equivalent
-                * to the one from the loose ref cache, except that
-                * we don't copy the peeled status, because we want it
-                * to be re-peeled.
+                * Add a reference creation for this reference to the
+                * packed-refs transaction:
                 */
-               add_packed_ref(refs->packed_ref_store, iter->refname, iter->oid);
+               if (ref_transaction_update(transaction, iter->refname,
+                                          iter->oid, NULL,
+                                          REF_NO_DEREF, NULL, &err))
+                       die("failure preparing to create packed reference %s: %s",
+                           iter->refname, err.buf);
 
                /* Schedule the loose reference for pruning if requested. */
                if ((flags & PACK_REFS_PRUNE)) {
                        struct ref_to_prune *n;
                        FLEX_ALLOC_STR(n, name, iter->refname);
-                       hashcpy(n->sha1, iter->oid->hash);
+                       oidcpy(&n->oid, iter->oid);
                        n->next = refs_to_prune;
                        refs_to_prune = n;
                }
@@ -1118,11 +1149,14 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
        if (ok != ITER_DONE)
                die("error while iterating over references");
 
-       if (commit_packed_refs(refs->packed_ref_store, &err))
-               die("unable to overwrite old ref-pack file: %s", err.buf);
+       if (ref_transaction_commit(transaction, &err))
+               die("unable to write new packed-refs: %s", err.buf);
+
+       ref_transaction_free(transaction);
+
        packed_refs_unlock(refs->packed_ref_store);
 
-       prune_refs(refs, refs_to_prune);
+       prune_refs(refs, &refs_to_prune);
        strbuf_release(&err);
        return 0;
 }
@@ -1141,7 +1175,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg,
        if (packed_refs_lock(refs->packed_ref_store, 0, &err))
                goto error;
 
-       if (repack_without_refs(refs->packed_ref_store, refnames, &err)) {
+       if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
                packed_refs_unlock(refs->packed_ref_store);
                goto error;
        }
@@ -1242,9 +1276,9 @@ static int commit_ref_update(struct files_ref_store *refs,
                             const struct object_id *oid, const char *logmsg,
                             struct strbuf *err);
 
-static int files_rename_ref(struct ref_store *ref_store,
+static int files_copy_or_rename_ref(struct ref_store *ref_store,
                            const char *oldrefname, const char *newrefname,
-                           const char *logmsg)
+                           const char *logmsg, int copy)
 {
        struct files_ref_store *refs =
                files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
@@ -1270,14 +1304,18 @@ static int files_rename_ref(struct ref_store *ref_store,
 
        if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
                                     RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-                               orig_oid.hash, &flag)) {
+                               &orig_oid, &flag)) {
                ret = error("refname %s not found", oldrefname);
                goto out;
        }
 
        if (flag & REF_ISSYMREF) {
-               ret = error("refname %s is a symbolic ref, renaming it is not supported",
-                           oldrefname);
+               if (copy)
+                       ret = error("refname %s is a symbolic ref, copying it is not supported",
+                                   oldrefname);
+               else
+                       ret = error("refname %s is a symbolic ref, renaming it is not supported",
+                                   oldrefname);
                goto out;
        }
        if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
@@ -1285,14 +1323,20 @@ static int files_rename_ref(struct ref_store *ref_store,
                goto out;
        }
 
-       if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
+       if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
                ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
                            oldrefname, strerror(errno));
                goto out;
        }
 
-       if (refs_delete_ref(&refs->base, logmsg, oldrefname,
-                           orig_oid.hash, REF_NODEREF)) {
+       if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
+               ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
+                           oldrefname, strerror(errno));
+               goto out;
+       }
+
+       if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
+                           &orig_oid, REF_NO_DEREF)) {
                error("unable to delete old %s", oldrefname);
                goto rollback;
        }
@@ -1304,11 +1348,11 @@ static int files_rename_ref(struct ref_store *ref_store,
         * the safety anyway; we want to delete the reference whatever
         * its current value.
         */
-       if (!refs_read_ref_full(&refs->base, newrefname,
+       if (!copy && !refs_read_ref_full(&refs->base, newrefname,
                                RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-                               oid.hash, NULL) &&
+                               &oid, NULL) &&
            refs_delete_ref(&refs->base, NULL, newrefname,
-                           NULL, REF_NODEREF)) {
+                           NULL, REF_NO_DEREF)) {
                if (errno == EISDIR) {
                        struct strbuf path = STRBUF_INIT;
                        int result;
@@ -1332,10 +1376,13 @@ static int files_rename_ref(struct ref_store *ref_store,
 
        logmoved = log;
 
-       lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
-                                  REF_NODEREF, NULL, &err);
+       lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL,
+                                 REF_NO_DEREF, NULL, &err);
        if (!lock) {
-               error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+               if (copy)
+                       error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+               else
+                       error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
                strbuf_release(&err);
                goto rollback;
        }
@@ -1352,8 +1399,8 @@ static int files_rename_ref(struct ref_store *ref_store,
        goto out;
 
  rollback:
-       lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
-                                  REF_NODEREF, NULL, &err);
+       lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL,
+                                 REF_NO_DEREF, NULL, &err);
        if (!lock) {
                error("unable to lock %s for rollback: %s", oldrefname, err.buf);
                strbuf_release(&err);
@@ -1386,6 +1433,22 @@ static int files_rename_ref(struct ref_store *ref_store,
        return ret;
 }
 
+static int files_rename_ref(struct ref_store *ref_store,
+                           const char *oldrefname, const char *newrefname,
+                           const char *logmsg)
+{
+       return files_copy_or_rename_ref(ref_store, oldrefname,
+                                newrefname, logmsg, 0);
+}
+
+static int files_copy_ref(struct ref_store *ref_store,
+                           const char *oldrefname, const char *newrefname,
+                           const char *logmsg)
+{
+       return files_copy_or_rename_ref(ref_store, oldrefname,
+                                newrefname, logmsg, 1);
+}
+
 static int close_ref_gently(struct ref_lock *lock)
 {
        if (close_lock_file_gently(&lock->lk))
@@ -1533,7 +1596,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
 
        written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
        free(logrec);
-       if (written != len)
+       if (written < 0)
                return -1;
 
        return 0;
@@ -1585,9 +1648,8 @@ static int files_log_ref_write(struct files_ref_store *refs,
 }
 
 /*
- * Write sha1 into the open lockfile, then close the lockfile. On
- * errors, rollback the lockfile, fill in *err and
- * return -1.
+ * Write oid into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile, fill in *err and return -1.
  */
 static int write_ref_to_lockfile(struct ref_lock *lock,
                                 const struct object_id *oid, struct strbuf *err)
@@ -1612,8 +1674,8 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
                return -1;
        }
        fd = get_lock_file_fd(&lock->lk);
-       if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
-           write_in_full(fd, &term, 1) != 1 ||
+       if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) < 0 ||
+           write_in_full(fd, &term, 1) < 0 ||
            close_ref_gently(lock) < 0) {
                strbuf_addf(err,
                            "couldn't write '%s'", get_lock_file_path(&lock->lk));
@@ -1660,13 +1722,12 @@ static int commit_ref_update(struct files_ref_store *refs,
                 * check with HEAD only which should cover 99% of all usage
                 * scenarios (even 100% of the default ones).
                 */
-               struct object_id head_oid;
                int head_flag;
                const char *head_ref;
 
                head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
                                                   RESOLVE_REF_READING,
-                                                  head_oid.hash, &head_flag);
+                                                  NULL, &head_flag);
                if (head_ref && (head_flag & REF_ISSYMREF) &&
                    !strcmp(head_ref, lock->ref_name)) {
                        struct strbuf log_err = STRBUF_INIT;
@@ -1712,7 +1773,7 @@ static void update_symref_reflog(struct files_ref_store *refs,
        struct object_id new_oid;
        if (logmsg &&
            !refs_read_ref_full(&refs->base, target,
-                               RESOLVE_REF_READING, new_oid.hash, NULL) &&
+                               RESOLVE_REF_READING, &new_oid, NULL) &&
            files_log_ref_write(refs, refname, &lock->old_oid,
                                &new_oid, logmsg, 0, &err)) {
                error("%s", err.buf);
@@ -1753,9 +1814,9 @@ static int files_create_symref(struct ref_store *ref_store,
        struct ref_lock *lock;
        int ret;
 
-       lock = lock_ref_sha1_basic(refs, refname, NULL,
-                                  NULL, NULL, REF_NODEREF, NULL,
-                                  &err);
+       lock = lock_ref_oid_basic(refs, refname, NULL,
+                                 NULL, NULL, REF_NO_DEREF, NULL,
+                                 &err);
        if (!lock) {
                error("%s", err.buf);
                strbuf_release(&err);
@@ -2001,7 +2062,7 @@ static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
 
                if (refs_read_ref_full(iter->ref_store,
                                       diter->relative_path, 0,
-                                      iter->oid.hash, &flags)) {
+                                      &iter->oid, &flags)) {
                        error("bad ref for %s", diter->path.buf);
                        continue;
                }
@@ -2050,7 +2111,7 @@ static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
        struct ref_iterator *ref_iterator = &iter->base;
        struct strbuf sb = STRBUF_INIT;
 
-       base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
+       base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
        strbuf_addf(&sb, "%s/logs", gitdir);
        iter->dir_iterator = dir_iterator_begin(sb.buf);
        iter->ref_store = ref_store;
@@ -2094,6 +2155,7 @@ static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_st
                return reflog_iterator_begin(ref_store, refs->gitcommondir);
        } else {
                return merge_ref_iterator_begin(
+                       0,
                        reflog_iterator_begin(ref_store, refs->gitdir),
                        reflog_iterator_begin(ref_store, refs->gitcommondir),
                        reflog_iterator_select, refs);
@@ -2114,7 +2176,7 @@ static int split_head_update(struct ref_update *update,
        struct ref_update *new_update;
 
        if ((update->flags & REF_LOG_ONLY) ||
-           (update->flags & REF_ISPRUNING) ||
+           (update->flags & REF_IS_PRUNING) ||
            (update->flags & REF_UPDATE_VIA_HEAD))
                return 0;
 
@@ -2137,8 +2199,8 @@ static int split_head_update(struct ref_update *update,
 
        new_update = ref_transaction_add_update(
                        transaction, "HEAD",
-                       update->flags | REF_LOG_ONLY | REF_NODEREF,
-                       update->new_oid.hash, update->old_oid.hash,
+                       update->flags | REF_LOG_ONLY | REF_NO_DEREF,
+                       &update->new_oid, &update->old_oid,
                        update->msg);
 
        /*
@@ -2156,8 +2218,8 @@ static int split_head_update(struct ref_update *update,
 
 /*
  * update is for a symref that points at referent and doesn't have
- * REF_NODEREF set. Split it into two updates:
- * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
+ * REF_NO_DEREF set. Split it into two updates:
+ * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set
  * - A new, separate update for the referent reference
  * Note that the new update will itself be subject to splitting when
  * the iteration gets to it.
@@ -2202,17 +2264,17 @@ static int split_symref_update(struct files_ref_store *refs,
 
        new_update = ref_transaction_add_update(
                        transaction, referent, new_flags,
-                       update->new_oid.hash, update->old_oid.hash,
+                       &update->new_oid, &update->old_oid,
                        update->msg);
 
        new_update->parent_update = update;
 
        /*
         * Change the symbolic ref update to log only. Also, it
-        * doesn't need to check its old SHA-1 value, as that will be
+        * doesn't need to check its old OID value, as that will be
         * done when new_update is processed.
         */
-       update->flags |= REF_LOG_ONLY | REF_NODEREF;
+       update->flags |= REF_LOG_ONLY | REF_NO_DEREF;
        update->flags &= ~REF_HAVE_OLD;
 
        /*
@@ -2278,10 +2340,10 @@ static int check_old_oid(struct ref_update *update, struct object_id *oid,
  * Prepare for carrying out update:
  * - Lock the reference referred to by update.
  * - Read the reference under lock.
- * - Check that its old SHA-1 value (if specified) is correct, and in
+ * - Check that its old OID value (if specified) is correct, and in
  *   any case record it in update->lock->old_oid for later use when
  *   writing the reflog.
- * - If it is a symref update without REF_NODEREF, split it up into a
+ * - If it is a symref update without REF_NO_DEREF, split it up into a
  *   REF_LOG_ONLY update of the symref and add a separate update for
  *   the referent to transaction.
  * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
@@ -2329,15 +2391,15 @@ static int lock_ref_for_update(struct files_ref_store *refs,
        update->backend_data = lock;
 
        if (update->type & REF_ISSYMREF) {
-               if (update->flags & REF_NODEREF) {
+               if (update->flags & REF_NO_DEREF) {
                        /*
                         * We won't be reading the referent as part of
                         * the transaction, so we have to read it here
-                        * to record and possibly check old_sha1:
+                        * to record and possibly check old_oid:
                         */
                        if (refs_read_ref_full(&refs->base,
                                               referent.buf, 0,
-                                              lock->old_oid.hash, NULL)) {
+                                              &lock->old_oid, NULL)) {
                                if (update->flags & REF_HAVE_OLD) {
                                        strbuf_addf(err, "cannot lock ref '%s': "
                                                    "error reading reference",
@@ -2353,7 +2415,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                        /*
                         * Create a new update for the reference this
                         * symref is pointing at. Also, we will record
-                        * and verify old_sha1 for this update as part
+                        * and verify old_oid for this update as part
                         * of processing the split-off update, so we
                         * don't have to do it here.
                         */
@@ -2373,7 +2435,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 
                /*
                 * If this update is happening indirectly because of a
-                * symref update, record the old SHA-1 in the parent
+                * symref update, record the old OID in the parent
                 * update:
                 */
                for (parent_update = update->parent_update;
@@ -2431,13 +2493,22 @@ static int lock_ref_for_update(struct files_ref_store *refs,
        return ret;
 }
 
+struct files_transaction_backend_data {
+       struct ref_transaction *packed_transaction;
+       int packed_refs_locked;
+};
+
 /*
  * Unlock any references in `transaction` that are still locked, and
  * mark the transaction closed.
  */
-static void files_transaction_cleanup(struct ref_transaction *transaction)
+static void files_transaction_cleanup(struct files_ref_store *refs,
+                                     struct ref_transaction *transaction)
 {
        size_t i;
+       struct files_transaction_backend_data *backend_data =
+               transaction->backend_data;
+       struct strbuf err = STRBUF_INIT;
 
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
@@ -2449,6 +2520,17 @@ static void files_transaction_cleanup(struct ref_transaction *transaction)
                }
        }
 
+       if (backend_data->packed_transaction &&
+           ref_transaction_abort(backend_data->packed_transaction, &err)) {
+               error("error aborting transaction: %s", err.buf);
+               strbuf_release(&err);
+       }
+
+       if (backend_data->packed_refs_locked)
+               packed_refs_unlock(refs->packed_ref_store);
+
+       free(backend_data);
+
        transaction->state = REF_TRANSACTION_CLOSED;
 }
 
@@ -2464,25 +2546,34 @@ static int files_transaction_prepare(struct ref_store *ref_store,
        struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
        char *head_ref = NULL;
        int head_type;
-       struct object_id head_oid;
+       struct files_transaction_backend_data *backend_data;
+       struct ref_transaction *packed_transaction = NULL;
 
        assert(err);
 
        if (!transaction->nr)
                goto cleanup;
 
+       backend_data = xcalloc(1, sizeof(*backend_data));
+       transaction->backend_data = backend_data;
+
        /*
         * Fail if a refname appears more than once in the
         * transaction. (If we end up splitting up any updates using
         * split_symref_update() or split_head_update(), those
         * functions will check that the new updates don't have the
-        * same refname as any existing ones.)
+        * same refname as any existing ones.) Also fail if any of the
+        * updates use REF_IS_PRUNING without REF_NO_DEREF.
         */
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
                struct string_list_item *item =
                        string_list_append(&affected_refnames, update->refname);
 
+               if ((update->flags & REF_IS_PRUNING) &&
+                   !(update->flags & REF_NO_DEREF))
+                       BUG("REF_IS_PRUNING set without REF_NO_DEREF");
+
                /*
                 * We store a pointer to update in item->util, but at
                 * the moment we never use the value of this field
@@ -2516,7 +2607,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
         */
        head_ref = refs_resolve_refdup(ref_store, "HEAD",
                                       RESOLVE_REF_NO_RECURSE,
-                                      head_oid.hash, &head_type);
+                                      NULL, &head_type);
 
        if (head_ref && !(head_type & REF_ISSYMREF)) {
                FREE_AND_NULL(head_ref);
@@ -2536,7 +2627,58 @@ static int files_transaction_prepare(struct ref_store *ref_store,
                ret = lock_ref_for_update(refs, update, transaction,
                                          head_ref, &affected_refnames, err);
                if (ret)
-                       break;
+                       goto cleanup;
+
+               if (update->flags & REF_DELETING &&
+                   !(update->flags & REF_LOG_ONLY) &&
+                   !(update->flags & REF_IS_PRUNING)) {
+                       /*
+                        * This reference has to be deleted from
+                        * packed-refs if it exists there.
+                        */
+                       if (!packed_transaction) {
+                               packed_transaction = ref_store_transaction_begin(
+                                               refs->packed_ref_store, err);
+                               if (!packed_transaction) {
+                                       ret = TRANSACTION_GENERIC_ERROR;
+                                       goto cleanup;
+                               }
+
+                               backend_data->packed_transaction =
+                                       packed_transaction;
+                       }
+
+                       ref_transaction_add_update(
+                                       packed_transaction, update->refname,
+                                       REF_HAVE_NEW | REF_NO_DEREF,
+                                       &update->new_oid, NULL,
+                                       NULL);
+               }
+       }
+
+       if (packed_transaction) {
+               if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
+                       ret = TRANSACTION_GENERIC_ERROR;
+                       goto cleanup;
+               }
+               backend_data->packed_refs_locked = 1;
+
+               if (is_packed_transaction_needed(refs->packed_ref_store,
+                                                packed_transaction)) {
+                       ret = ref_transaction_prepare(packed_transaction, err);
+               } else {
+                       /*
+                        * We can skip rewriting the `packed-refs`
+                        * file. But we do need to leave it locked, so
+                        * that somebody else doesn't pack a reference
+                        * that we are trying to delete.
+                        */
+                       if (ref_transaction_abort(packed_transaction, err)) {
+                               ret = TRANSACTION_GENERIC_ERROR;
+                               goto cleanup;
+                       }
+                       backend_data->packed_transaction = NULL;
+               }
        }
 
 cleanup:
@@ -2544,7 +2686,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
        string_list_clear(&affected_refnames, 0);
 
        if (ret)
-               files_transaction_cleanup(transaction);
+               files_transaction_cleanup(refs, transaction);
        else
                transaction->state = REF_TRANSACTION_PREPARED;
 
@@ -2559,9 +2701,10 @@ static int files_transaction_finish(struct ref_store *ref_store,
                files_downcast(ref_store, 0, "ref_transaction_finish");
        size_t i;
        int ret = 0;
-       struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
-       struct string_list_item *ref_to_delete;
        struct strbuf sb = STRBUF_INIT;
+       struct files_transaction_backend_data *backend_data;
+       struct ref_transaction *packed_transaction;
+
 
        assert(err);
 
@@ -2570,6 +2713,9 @@ static int files_transaction_finish(struct ref_store *ref_store,
                return 0;
        }
 
+       backend_data = transaction->backend_data;
+       packed_transaction = backend_data->packed_transaction;
+
        /* Perform updates first so live commits remain referenced */
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
@@ -2605,7 +2751,44 @@ static int files_transaction_finish(struct ref_store *ref_store,
                        }
                }
        }
-       /* Perform deletes now that updates are safely completed */
+
+       /*
+        * Now that updates are safely completed, we can perform
+        * deletes. First delete the reflogs of any references that
+        * will be deleted, since (in the unexpected event of an
+        * error) leaving a reference without a reflog is less bad
+        * than leaving a reflog without a reference (the latter is a
+        * mildly invalid repository state):
+        */
+       for (i = 0; i < transaction->nr; i++) {
+               struct ref_update *update = transaction->updates[i];
+               if (update->flags & REF_DELETING &&
+                   !(update->flags & REF_LOG_ONLY) &&
+                   !(update->flags & REF_IS_PRUNING)) {
+                       strbuf_reset(&sb);
+                       files_reflog_path(refs, &sb, update->refname);
+                       if (!unlink_or_warn(sb.buf))
+                               try_remove_empty_parents(refs, update->refname,
+                                                        REMOVE_EMPTY_PARENTS_REFLOG);
+               }
+       }
+
+       /*
+        * Perform deletes now that updates are safely completed.
+        *
+        * First delete any packed versions of the references, while
+        * retaining the packed-refs lock:
+        */
+       if (packed_transaction) {
+               ret = ref_transaction_commit(packed_transaction, err);
+               ref_transaction_free(packed_transaction);
+               packed_transaction = NULL;
+               backend_data->packed_transaction = NULL;
+               if (ret)
+                       goto cleanup;
+       }
+
+       /* Now delete the loose versions of the references: */
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
                struct ref_lock *lock = update->backend_data;
@@ -2623,39 +2806,13 @@ static int files_transaction_finish(struct ref_store *ref_store,
                                }
                                update->flags |= REF_DELETED_LOOSE;
                        }
-
-                       if (!(update->flags & REF_ISPRUNING))
-                               string_list_append(&refs_to_delete,
-                                                  lock->ref_name);
                }
        }
 
-       if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
-               ret = TRANSACTION_GENERIC_ERROR;
-               goto cleanup;
-       }
-
-       if (repack_without_refs(refs->packed_ref_store, &refs_to_delete, err)) {
-               ret = TRANSACTION_GENERIC_ERROR;
-               packed_refs_unlock(refs->packed_ref_store);
-               goto cleanup;
-       }
-
-       packed_refs_unlock(refs->packed_ref_store);
-
-       /* Delete the reflogs of any references that were deleted: */
-       for_each_string_list_item(ref_to_delete, &refs_to_delete) {
-               strbuf_reset(&sb);
-               files_reflog_path(refs, &sb, ref_to_delete->string);
-               if (!unlink_or_warn(sb.buf))
-                       try_remove_empty_parents(refs, ref_to_delete->string,
-                                                REMOVE_EMPTY_PARENTS_REFLOG);
-       }
-
        clear_loose_ref_cache(refs);
 
 cleanup:
-       files_transaction_cleanup(transaction);
+       files_transaction_cleanup(refs, transaction);
 
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
@@ -2673,7 +2830,6 @@ static int files_transaction_finish(struct ref_store *ref_store,
        }
 
        strbuf_release(&sb);
-       string_list_clear(&refs_to_delete, 0);
        return ret;
 }
 
@@ -2681,7 +2837,10 @@ static int files_transaction_abort(struct ref_store *ref_store,
                                   struct ref_transaction *transaction,
                                   struct strbuf *err)
 {
-       files_transaction_cleanup(transaction);
+       struct files_ref_store *refs =
+               files_downcast(ref_store, 0, "ref_transaction_abort");
+
+       files_transaction_cleanup(refs, transaction);
        return 0;
 }
 
@@ -2703,6 +2862,7 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
        size_t i;
        int ret = 0;
        struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+       struct ref_transaction *packed_transaction = NULL;
 
        assert(err);
 
@@ -2735,6 +2895,12 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
                                 &affected_refnames))
                die("BUG: initial ref transaction called with existing refs");
 
+       packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
+       if (!packed_transaction) {
+               ret = TRANSACTION_GENERIC_ERROR;
+               goto cleanup;
+       }
+
        for (i = 0; i < transaction->nr; i++) {
                struct ref_update *update = transaction->updates[i];
 
@@ -2747,6 +2913,15 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
                        ret = TRANSACTION_NAME_CONFLICT;
                        goto cleanup;
                }
+
+               /*
+                * Add a reference creation for this reference to the
+                * packed-refs transaction:
+                */
+               ref_transaction_add_update(packed_transaction, update->refname,
+                                          update->flags & ~REF_HAVE_OLD,
+                                          &update->new_oid, &update->old_oid,
+                                          NULL);
        }
 
        if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
@@ -2754,21 +2929,14 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
                goto cleanup;
        }
 
-       for (i = 0; i < transaction->nr; i++) {
-               struct ref_update *update = transaction->updates[i];
-
-               if ((update->flags & REF_HAVE_NEW) &&
-                   !is_null_oid(&update->new_oid))
-                       add_packed_ref(refs->packed_ref_store, update->refname,
-                                      &update->new_oid);
-       }
-
-       if (commit_packed_refs(refs->packed_ref_store, err)) {
+       if (initial_ref_transaction_commit(packed_transaction, err)) {
                ret = TRANSACTION_GENERIC_ERROR;
                goto cleanup;
        }
 
 cleanup:
+       if (packed_transaction)
+               ref_transaction_free(packed_transaction);
        packed_refs_unlock(refs->packed_ref_store);
        transaction->state = REF_TRANSACTION_CLOSED;
        string_list_clear(&affected_refnames, 0);
@@ -2813,7 +2981,7 @@ static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
 }
 
 static int files_reflog_expire(struct ref_store *ref_store,
-                              const char *refname, const unsigned char *sha1,
+                              const char *refname, const struct object_id *oid,
                               unsigned int flags,
                               reflog_expiry_prepare_fn prepare_fn,
                               reflog_expiry_should_prune_fn should_prune_fn,
@@ -2830,7 +2998,6 @@ static int files_reflog_expire(struct ref_store *ref_store,
        int status = 0;
        int type;
        struct strbuf err = STRBUF_INIT;
-       struct object_id oid;
 
        memset(&cb, 0, sizeof(cb));
        cb.flags = flags;
@@ -2842,9 +3009,9 @@ static int files_reflog_expire(struct ref_store *ref_store,
         * reference itself, plus we might need to update the
         * reference if --updateref was specified:
         */
-       lock = lock_ref_sha1_basic(refs, refname, sha1,
-                                  NULL, NULL, REF_NODEREF,
-                                  &type, &err);
+       lock = lock_ref_oid_basic(refs, refname, oid,
+                                 NULL, NULL, REF_NO_DEREF,
+                                 &type, &err);
        if (!lock) {
                error("cannot lock ref '%s': %s", refname, err.buf);
                strbuf_release(&err);
@@ -2880,9 +3047,7 @@ static int files_reflog_expire(struct ref_store *ref_store,
                }
        }
 
-       hashcpy(oid.hash, sha1);
-
-       (*prepare_fn)(refname, &oid, cb.policy_cb);
+       (*prepare_fn)(refname, oid, cb.policy_cb);
        refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
        (*cleanup_fn)(cb.policy_cb);
 
@@ -2904,8 +3069,8 @@ static int files_reflog_expire(struct ref_store *ref_store,
                        rollback_lock_file(&reflog_lock);
                } else if (update &&
                           (write_in_full(get_lock_file_fd(&lock->lk),
-                               oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
-                           write_str_in_full(get_lock_file_fd(&lock->lk), "\n") != 1 ||
+                               oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) < 0 ||
+                           write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
                            close_ref_gently(lock) < 0)) {
                        status |= error("couldn't write %s",
                                        get_lock_file_path(&lock->lk));
@@ -2959,10 +3124,10 @@ struct ref_storage_be refs_be_files = {
        files_initial_transaction_commit,
 
        files_pack_refs,
-       files_peel_ref,
        files_create_symref,
        files_delete_refs,
        files_rename_ref,
+       files_copy_ref,
 
        files_ref_iterator_begin,
        files_read_raw_ref,