builtin/blame: convert file to use struct object_id
[gitweb.git] / refs / files-backend.c
index a783513435a5b0f900d4e165cc1fb637151c9b65..12290d249643b5aaab18961ca91637910d0d7261 100644 (file)
@@ -1,13 +1,14 @@
 #include "../cache.h"
 #include "../refs.h"
 #include "refs-internal.h"
+#include "../iterator.h"
+#include "../dir-iterator.h"
 #include "../lockfile.h"
 #include "../object.h"
 #include "../dir.h"
 
 struct ref_lock {
        char *ref_name;
-       char *orig_ref_name;
        struct lock_file *lk;
        struct object_id old_oid;
 };
@@ -514,68 +515,36 @@ static void sort_ref_dir(struct ref_dir *dir)
 }
 
 /*
- * Return true iff the reference described by entry can be resolved to
- * an object in the database.  Emit a warning if the referred-to
- * object does not exist.
+ * 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.
  */
-static int ref_resolves_to_object(struct ref_entry *entry)
+static int ref_resolves_to_object(const char *refname,
+                                 const struct object_id *oid,
+                                 unsigned int flags)
 {
-       if (entry->flag & REF_ISBROKEN)
+       if (flags & REF_ISBROKEN)
                return 0;
-       if (!has_sha1_file(entry->u.value.oid.hash)) {
-               error("%s does not point to a valid object!", entry->name);
+       if (!has_sha1_file(oid->hash)) {
+               error("%s does not point to a valid object!", refname);
                return 0;
        }
        return 1;
 }
 
 /*
- * current_ref is a performance hack: when iterating over references
- * using the for_each_ref*() functions, current_ref is set to the
- * current reference's entry before calling the callback function.  If
- * the callback function calls peel_ref(), then peel_ref() first
- * checks whether the reference to be peeled is the current reference
- * (it usually is) and if so, returns that reference's peeled version
- * if it is available.  This avoids a refname lookup in a common case.
- */
-static struct ref_entry *current_ref;
-
-typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
-
-struct ref_entry_cb {
-       const char *base;
-       int trim;
-       int flags;
-       each_ref_fn *fn;
-       void *cb_data;
-};
-
-/*
- * Handle one reference in a do_for_each_ref*()-style iteration,
- * calling an each_ref_fn for each entry.
+ * Return true if the reference described by entry can be resolved to
+ * an object in the database; otherwise, emit a warning and return
+ * false.
  */
-static int do_one_ref(struct ref_entry *entry, void *cb_data)
+static int entry_resolves_to_object(struct ref_entry *entry)
 {
-       struct ref_entry_cb *data = cb_data;
-       struct ref_entry *old_current_ref;
-       int retval;
-
-       if (!starts_with(entry->name, data->base))
-               return 0;
-
-       if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
-             !ref_resolves_to_object(entry))
-               return 0;
-
-       /* Store the old value, in case this is a recursive call: */
-       old_current_ref = current_ref;
-       current_ref = entry;
-       retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
-                         entry->flag, data->cb_data);
-       current_ref = old_current_ref;
-       return retval;
+       return ref_resolves_to_object(entry->name,
+                                     &entry->u.value.oid, entry->flag);
 }
 
+typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
+
 /*
  * Call fn for each reference in dir that has index in the range
  * offset <= index < dir->nr.  Recurse into subdirectories that are in
@@ -604,78 +573,6 @@ static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
        return 0;
 }
 
-/*
- * Call fn for each reference in the union of dir1 and dir2, in order
- * by refname.  Recurse into subdirectories.  If a value entry appears
- * in both dir1 and dir2, then only process the version that is in
- * dir2.  The input dirs must already be sorted, but subdirs will be
- * sorted as needed.  fn is called for all references, including
- * broken ones.
- */
-static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
-                                    struct ref_dir *dir2,
-                                    each_ref_entry_fn fn, void *cb_data)
-{
-       int retval;
-       int i1 = 0, i2 = 0;
-
-       assert(dir1->sorted == dir1->nr);
-       assert(dir2->sorted == dir2->nr);
-       while (1) {
-               struct ref_entry *e1, *e2;
-               int cmp;
-               if (i1 == dir1->nr) {
-                       return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
-               }
-               if (i2 == dir2->nr) {
-                       return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
-               }
-               e1 = dir1->entries[i1];
-               e2 = dir2->entries[i2];
-               cmp = strcmp(e1->name, e2->name);
-               if (cmp == 0) {
-                       if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
-                               /* Both are directories; descend them in parallel. */
-                               struct ref_dir *subdir1 = get_ref_dir(e1);
-                               struct ref_dir *subdir2 = get_ref_dir(e2);
-                               sort_ref_dir(subdir1);
-                               sort_ref_dir(subdir2);
-                               retval = do_for_each_entry_in_dirs(
-                                               subdir1, subdir2, fn, cb_data);
-                               i1++;
-                               i2++;
-                       } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
-                               /* Both are references; ignore the one from dir1. */
-                               retval = fn(e2, cb_data);
-                               i1++;
-                               i2++;
-                       } else {
-                               die("conflict between reference and directory: %s",
-                                   e1->name);
-                       }
-               } else {
-                       struct ref_entry *e;
-                       if (cmp < 0) {
-                               e = e1;
-                               i1++;
-                       } else {
-                               e = e2;
-                               i2++;
-                       }
-                       if (e->flag & REF_DIR) {
-                               struct ref_dir *subdir = get_ref_dir(e);
-                               sort_ref_dir(subdir);
-                               retval = do_for_each_entry_in_dir(
-                                               subdir, 0, fn, cb_data);
-                       } else {
-                               retval = fn(e, cb_data);
-                       }
-               }
-               if (retval)
-                       return retval;
-       }
-}
-
 /*
  * Load all of the refs from the dir into our in-memory cache. The hard work
  * of loading loose refs is done by get_ref_dir(), so we just need to recurse
@@ -692,6 +589,153 @@ static void prime_ref_dir(struct ref_dir *dir)
        }
 }
 
+/*
+ * A level in the reference hierarchy that is currently being iterated
+ * through.
+ */
+struct cache_ref_iterator_level {
+       /*
+        * The ref_dir being iterated over at this level. The ref_dir
+        * is sorted before being stored here.
+        */
+       struct ref_dir *dir;
+
+       /*
+        * The index of the current entry within dir (which might
+        * itself be a directory). If index == -1, then the iteration
+        * hasn't yet begun. If index == dir->nr, then the iteration
+        * through this level is over.
+        */
+       int index;
+};
+
+/*
+ * Represent an iteration through a ref_dir in the memory cache. The
+ * iteration recurses through subdirectories.
+ */
+struct cache_ref_iterator {
+       struct ref_iterator base;
+
+       /*
+        * The number of levels currently on the stack. This is always
+        * at least 1, because when it becomes zero the iteration is
+        * ended and this struct is freed.
+        */
+       size_t levels_nr;
+
+       /* The number of levels that have been allocated on the stack */
+       size_t levels_alloc;
+
+       /*
+        * A stack of levels. levels[0] is the uppermost level that is
+        * being iterated over in this iteration. (This is not
+        * necessary the top level in the references hierarchy. If we
+        * are iterating through a subtree, then levels[0] will hold
+        * the ref_dir for that subtree, and subsequent levels will go
+        * on from there.)
+        */
+       struct cache_ref_iterator_level *levels;
+};
+
+static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+       struct cache_ref_iterator *iter =
+               (struct cache_ref_iterator *)ref_iterator;
+
+       while (1) {
+               struct cache_ref_iterator_level *level =
+                       &iter->levels[iter->levels_nr - 1];
+               struct ref_dir *dir = level->dir;
+               struct ref_entry *entry;
+
+               if (level->index == -1)
+                       sort_ref_dir(dir);
+
+               if (++level->index == level->dir->nr) {
+                       /* This level is exhausted; pop up a level */
+                       if (--iter->levels_nr == 0)
+                               return ref_iterator_abort(ref_iterator);
+
+                       continue;
+               }
+
+               entry = dir->entries[level->index];
+
+               if (entry->flag & REF_DIR) {
+                       /* push down a level */
+                       ALLOC_GROW(iter->levels, iter->levels_nr + 1,
+                                  iter->levels_alloc);
+
+                       level = &iter->levels[iter->levels_nr++];
+                       level->dir = get_ref_dir(entry);
+                       level->index = -1;
+               } else {
+                       iter->base.refname = entry->name;
+                       iter->base.oid = &entry->u.value.oid;
+                       iter->base.flags = entry->flag;
+                       return ITER_OK;
+               }
+       }
+}
+
+static enum peel_status peel_entry(struct ref_entry *entry, int repeel);
+
+static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
+                                  struct object_id *peeled)
+{
+       struct cache_ref_iterator *iter =
+               (struct cache_ref_iterator *)ref_iterator;
+       struct cache_ref_iterator_level *level;
+       struct ref_entry *entry;
+
+       level = &iter->levels[iter->levels_nr - 1];
+
+       if (level->index == -1)
+               die("BUG: peel called before advance for cache iterator");
+
+       entry = level->dir->entries[level->index];
+
+       if (peel_entry(entry, 0))
+               return -1;
+       hashcpy(peeled->hash, entry->u.value.peeled.hash);
+       return 0;
+}
+
+static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+       struct cache_ref_iterator *iter =
+               (struct cache_ref_iterator *)ref_iterator;
+
+       free(iter->levels);
+       base_ref_iterator_free(ref_iterator);
+       return ITER_DONE;
+}
+
+static struct ref_iterator_vtable cache_ref_iterator_vtable = {
+       cache_ref_iterator_advance,
+       cache_ref_iterator_peel,
+       cache_ref_iterator_abort
+};
+
+static struct ref_iterator *cache_ref_iterator_begin(struct ref_dir *dir)
+{
+       struct cache_ref_iterator *iter;
+       struct ref_iterator *ref_iterator;
+       struct cache_ref_iterator_level *level;
+
+       iter = xcalloc(1, sizeof(*iter));
+       ref_iterator = &iter->base;
+       base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
+       ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
+
+       iter->levels_nr = 1;
+       level = &iter->levels[0];
+       level->index = -1;
+       level->dir = dir;
+
+       return ref_iterator;
+}
+
 struct nonmatching_ref_data {
        const struct string_list *skip;
        const char *conflicting_refname;
@@ -955,15 +999,26 @@ static struct ref_cache *lookup_ref_cache(const char *submodule)
 
 /*
  * Return a pointer to a ref_cache for the specified submodule. For
- * the main repository, use submodule==NULL. The returned structure
- * will be allocated and initialized but not necessarily populated; it
- * should not be freed.
+ * the main repository, use submodule==NULL; such a call cannot fail.
+ * For a submodule, the submodule must exist and be a nonbare
+ * repository, otherwise return NULL.
+ *
+ * The returned structure will be allocated and initialized but not
+ * necessarily populated; it should not be freed.
  */
 static struct ref_cache *get_ref_cache(const char *submodule)
 {
        struct ref_cache *refs = lookup_ref_cache(submodule);
-       if (!refs)
-               refs = create_ref_cache(submodule);
+
+       if (!refs) {
+               struct strbuf submodule_sb = STRBUF_INIT;
+
+               strbuf_addstr(&submodule_sb, submodule);
+               if (is_nonbare_repository_dir(&submodule_sb))
+                       refs = create_ref_cache(submodule);
+               strbuf_release(&submodule_sb);
+       }
+
        return refs;
 }
 
@@ -1342,13 +1397,10 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sh
                return -1;
 
        strbuf_add(&submodule, path, len);
-       refs = lookup_ref_cache(submodule.buf);
+       refs = get_ref_cache(submodule.buf);
        if (!refs) {
-               if (!is_nonbare_repository_dir(&submodule)) {
-                       strbuf_release(&submodule);
-                       return -1;
-               }
-               refs = create_ref_cache(submodule.buf);
+               strbuf_release(&submodule);
+               return -1;
        }
        strbuf_release(&submodule);
 
@@ -1522,7 +1574,6 @@ static void unlock_ref(struct ref_lock *lock)
        if (lock->lk)
                rollback_lock_file(lock->lk);
        free(lock->ref_name);
-       free(lock->orig_ref_name);
        free(lock);
 }
 
@@ -1576,7 +1627,6 @@ static int lock_raw_ref(const char *refname, int mustexist,
        *lock_p = lock = xcalloc(1, sizeof(*lock));
 
        lock->ref_name = xstrdup(refname);
-       lock->orig_ref_name = xstrdup(refname);
        strbuf_git_path(&ref_file, "%s", refname);
 
 retry:
@@ -1793,11 +1843,12 @@ int peel_ref(const char *refname, unsigned char *sha1)
        int flag;
        unsigned char base[20];
 
-       if (current_ref && (current_ref->name == refname
-                           || !strcmp(current_ref->name, refname))) {
-               if (peel_entry(current_ref, 0))
+       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, current_ref->u.value.peeled.hash);
+               hashcpy(sha1, peeled.hash);
                return 0;
        }
 
@@ -1825,90 +1876,137 @@ int peel_ref(const char *refname, unsigned char *sha1)
        return peel_object(base, sha1);
 }
 
-/*
- * Call fn for each reference in the specified ref_cache, omitting
- * references not in the containing_dir of base.  fn is called for all
- * references, including broken ones.  If fn ever returns a non-zero
- * value, stop the iteration and return that value; otherwise, return
- * 0.
- */
-static int do_for_each_entry(struct ref_cache *refs, const char *base,
-                            each_ref_entry_fn fn, void *cb_data)
-{
+struct files_ref_iterator {
+       struct ref_iterator base;
+
        struct packed_ref_cache *packed_ref_cache;
-       struct ref_dir *loose_dir;
-       struct ref_dir *packed_dir;
-       int retval = 0;
+       struct ref_iterator *iter0;
+       unsigned int flags;
+};
 
-       /*
-        * We must make sure that all loose refs are read before accessing the
-        * packed-refs file; this avoids a race condition in which loose refs
-        * are migrated to the packed-refs file by a simultaneous process, but
-        * our in-memory view is from before the migration. get_packed_ref_cache()
-        * takes care of making sure our view is up to date with what is on
-        * disk.
-        */
-       loose_dir = get_loose_refs(refs);
-       if (base && *base) {
-               loose_dir = find_containing_dir(loose_dir, base, 0);
-       }
-       if (loose_dir)
-               prime_ref_dir(loose_dir);
+static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+       struct files_ref_iterator *iter =
+               (struct files_ref_iterator *)ref_iterator;
+       int ok;
 
-       packed_ref_cache = get_packed_ref_cache(refs);
-       acquire_packed_ref_cache(packed_ref_cache);
-       packed_dir = get_packed_ref_dir(packed_ref_cache);
-       if (base && *base) {
-               packed_dir = find_containing_dir(packed_dir, base, 0);
-       }
-
-       if (packed_dir && loose_dir) {
-               sort_ref_dir(packed_dir);
-               sort_ref_dir(loose_dir);
-               retval = do_for_each_entry_in_dirs(
-                               packed_dir, loose_dir, fn, cb_data);
-       } else if (packed_dir) {
-               sort_ref_dir(packed_dir);
-               retval = do_for_each_entry_in_dir(
-                               packed_dir, 0, fn, cb_data);
-       } else if (loose_dir) {
-               sort_ref_dir(loose_dir);
-               retval = do_for_each_entry_in_dir(
-                               loose_dir, 0, fn, cb_data);
+       while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
+               if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
+                   !ref_resolves_to_object(iter->iter0->refname,
+                                           iter->iter0->oid,
+                                           iter->iter0->flags))
+                       continue;
+
+               iter->base.refname = iter->iter0->refname;
+               iter->base.oid = iter->iter0->oid;
+               iter->base.flags = iter->iter0->flags;
+               return ITER_OK;
        }
 
-       release_packed_ref_cache(packed_ref_cache);
-       return retval;
+       iter->iter0 = NULL;
+       if (ref_iterator_abort(ref_iterator) != ITER_DONE)
+               ok = ITER_ERROR;
+
+       return ok;
 }
 
-/*
- * Call fn for each reference in the specified ref_cache for which the
- * refname begins with base.  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.
- */
-int do_for_each_ref(const char *submodule, const char *base,
-                   each_ref_fn fn, int trim, int flags, void *cb_data)
+static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
+                                  struct object_id *peeled)
 {
-       struct ref_entry_cb data;
-       struct ref_cache *refs;
+       struct files_ref_iterator *iter =
+               (struct files_ref_iterator *)ref_iterator;
+
+       return ref_iterator_peel(iter->iter0, peeled);
+}
+
+static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+       struct files_ref_iterator *iter =
+               (struct files_ref_iterator *)ref_iterator;
+       int ok = ITER_DONE;
+
+       if (iter->iter0)
+               ok = ref_iterator_abort(iter->iter0);
+
+       release_packed_ref_cache(iter->packed_ref_cache);
+       base_ref_iterator_free(ref_iterator);
+       return ok;
+}
+
+static struct ref_iterator_vtable files_ref_iterator_vtable = {
+       files_ref_iterator_advance,
+       files_ref_iterator_peel,
+       files_ref_iterator_abort
+};
 
-       refs = get_ref_cache(submodule);
-       data.base = base;
-       data.trim = trim;
-       data.flags = flags;
-       data.fn = fn;
-       data.cb_data = cb_data;
+struct ref_iterator *files_ref_iterator_begin(
+               const char *submodule,
+               const char *prefix, unsigned int flags)
+{
+       struct ref_cache *refs = get_ref_cache(submodule);
+       struct ref_dir *loose_dir, *packed_dir;
+       struct ref_iterator *loose_iter, *packed_iter;
+       struct files_ref_iterator *iter;
+       struct ref_iterator *ref_iterator;
+
+       if (!refs)
+               return empty_ref_iterator_begin();
 
        if (ref_paranoia < 0)
                ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
        if (ref_paranoia)
-               data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+               flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+
+       iter = xcalloc(1, sizeof(*iter));
+       ref_iterator = &iter->base;
+       base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
 
-       return do_for_each_entry(refs, base, do_one_ref, &data);
+       /*
+        * We must make sure that all loose refs are read before
+        * accessing the packed-refs file; this avoids a race
+        * condition if loose refs are migrated to the packed-refs
+        * file by a simultaneous process, but our in-memory view is
+        * from before the migration. We ensure this as follows:
+        * First, we call prime_ref_dir(), which pre-reads the loose
+        * references for the subtree into the cache. (If they've
+        * already been read, that's OK; we only need to guarantee
+        * that they're read before the packed refs, not *how much*
+        * before.) After that, we call get_packed_ref_cache(), which
+        * internally checks whether the packed-ref cache is up to
+        * date with what is on disk, and re-reads it if not.
+        */
+
+       loose_dir = get_loose_refs(refs);
+
+       if (prefix && *prefix)
+               loose_dir = find_containing_dir(loose_dir, prefix, 0);
+
+       if (loose_dir) {
+               prime_ref_dir(loose_dir);
+               loose_iter = cache_ref_iterator_begin(loose_dir);
+       } else {
+               /* There's nothing to iterate over. */
+               loose_iter = empty_ref_iterator_begin();
+       }
+
+       iter->packed_ref_cache = get_packed_ref_cache(refs);
+       acquire_packed_ref_cache(iter->packed_ref_cache);
+       packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
+
+       if (prefix && *prefix)
+               packed_dir = find_containing_dir(packed_dir, prefix, 0);
+
+       if (packed_dir) {
+               packed_iter = cache_ref_iterator_begin(packed_dir);
+       } else {
+               /* There's nothing to iterate over. */
+               packed_iter = empty_ref_iterator_begin();
+       }
+
+       iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
+       iter->flags = flags;
+
+       return ref_iterator;
 }
 
 /*
@@ -1932,14 +2030,14 @@ static int verify_lock(struct ref_lock *lock,
                        errno = save_errno;
                        return -1;
                } else {
-                       hashclr(lock->old_oid.hash);
+                       oidclr(&lock->old_oid);
                        return 0;
                }
        }
        if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
                strbuf_addf(err, "ref '%s' is at %s but expected %s",
                            lock->ref_name,
-                           sha1_to_hex(lock->old_oid.hash),
+                           oid_to_hex(&lock->old_oid),
                            sha1_to_hex(old_sha1));
                errno = EBUSY;
                return -1;
@@ -1969,14 +2067,13 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                                            struct strbuf *err)
 {
        struct strbuf ref_file = STRBUF_INIT;
-       struct strbuf orig_ref_file = STRBUF_INIT;
-       const char *orig_refname = refname;
        struct ref_lock *lock;
        int last_errno = 0;
-       int lflags = 0;
+       int lflags = LOCK_NO_DEREF;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
-       int resolve_flags = 0;
+       int resolve_flags = RESOLVE_REF_NO_RECURSE;
        int attempts_remaining = 3;
+       int resolved;
 
        assert(err);
 
@@ -1986,46 +2083,39 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                resolve_flags |= RESOLVE_REF_READING;
        if (flags & REF_DELETING)
                resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
-       if (flags & REF_NODEREF) {
-               resolve_flags |= RESOLVE_REF_NO_RECURSE;
-               lflags |= LOCK_NO_DEREF;
-       }
 
-       refname = resolve_ref_unsafe(refname, resolve_flags,
-                                    lock->old_oid.hash, type);
-       if (!refname && errno == EISDIR) {
+       strbuf_git_path(&ref_file, "%s", refname);
+       resolved = !!resolve_ref_unsafe(refname, resolve_flags,
+                                       lock->old_oid.hash, type);
+       if (!resolved && errno == EISDIR) {
                /*
                 * we are trying to lock foo but we used to
                 * have foo/bar which now does not exist;
                 * it is normal for the empty directory 'foo'
                 * to remain.
                 */
-               strbuf_git_path(&orig_ref_file, "%s", orig_refname);
-               if (remove_empty_directories(&orig_ref_file)) {
+               if (remove_empty_directories(&ref_file)) {
                        last_errno = errno;
-                       if (!verify_refname_available_dir(orig_refname, extras, skip,
+                       if (!verify_refname_available_dir(refname, extras, skip,
                                                          get_loose_refs(&ref_cache), err))
                                strbuf_addf(err, "there are still refs under '%s'",
-                                           orig_refname);
+                                           refname);
                        goto error_return;
                }
-               refname = resolve_ref_unsafe(orig_refname, resolve_flags,
-                                            lock->old_oid.hash, type);
+               resolved = !!resolve_ref_unsafe(refname, resolve_flags,
+                                               lock->old_oid.hash, type);
        }
-       if (!refname) {
+       if (!resolved) {
                last_errno = errno;
                if (last_errno != ENOTDIR ||
-                   !verify_refname_available_dir(orig_refname, extras, skip,
+                   !verify_refname_available_dir(refname, extras, skip,
                                                  get_loose_refs(&ref_cache), err))
                        strbuf_addf(err, "unable to resolve reference '%s': %s",
-                                   orig_refname, strerror(last_errno));
+                                   refname, strerror(last_errno));
 
                goto error_return;
        }
 
-       if (flags & REF_NODEREF)
-               refname = orig_refname;
-
        /*
         * If the ref did not exist and we are creating it, make sure
         * there is no existing packed ref whose name begins with our
@@ -2042,8 +2132,6 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        lock->lk = xcalloc(1, sizeof(struct lock_file));
 
        lock->ref_name = xstrdup(refname);
-       lock->orig_ref_name = xstrdup(orig_refname);
-       strbuf_git_path(&ref_file, "%s", refname);
 
  retry:
        switch (safe_create_leading_directories_const(ref_file.buf)) {
@@ -2086,7 +2174,6 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
  out:
        strbuf_release(&ref_file);
-       strbuf_release(&orig_ref_file);
        errno = last_errno;
        return lock;
 }
@@ -2240,7 +2327,7 @@ static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
                return 0;
 
        /* Do not pack symbolic or broken refs: */
-       if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
+       if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
                return 0;
 
        /* Add a packed ref cache entry equivalent to the loose entry. */
@@ -2426,7 +2513,7 @@ static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
        return 0;
 }
 
-int delete_refs(struct string_list *refnames)
+int delete_refs(struct string_list *refnames, unsigned int flags)
 {
        struct strbuf err = STRBUF_INIT;
        int i, result = 0;
@@ -2455,7 +2542,7 @@ int delete_refs(struct string_list *refnames)
        for (i = 0; i < refnames->nr; i++) {
                const char *refname = refnames->items[i].string;
 
-               if (delete_ref(refname, NULL, 0))
+               if (delete_ref(refname, NULL, flags))
                        result |= error(_("could not remove reference %s"), refname);
        }
 
@@ -2546,7 +2633,7 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
                                 const unsigned char *sha1, struct strbuf *err);
 static int commit_ref_update(struct ref_lock *lock,
                             const unsigned char *sha1, const char *logmsg,
-                            int flags, struct strbuf *err);
+                            struct strbuf *err);
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
@@ -2622,7 +2709,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        hashcpy(lock->old_oid.hash, orig_sha1);
 
        if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-           commit_ref_update(lock, orig_sha1, logmsg, 0, &err)) {
+           commit_ref_update(lock, orig_sha1, logmsg, &err)) {
                error("unable to write current sha1 into %s: %s", newrefname, err.buf);
                strbuf_release(&err);
                goto rollback;
@@ -2642,7 +2729,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        flag = log_all_ref_updates;
        log_all_ref_updates = 0;
        if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-           commit_ref_update(lock, orig_sha1, NULL, 0, &err)) {
+           commit_ref_update(lock, orig_sha1, NULL, &err)) {
                error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
                strbuf_release(&err);
        }
@@ -2880,12 +2967,10 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
  */
 static int commit_ref_update(struct ref_lock *lock,
                             const unsigned char *sha1, const char *logmsg,
-                            int flags, struct strbuf *err)
+                            struct strbuf *err)
 {
        clear_loose_ref_cache(&ref_cache);
-       if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0 ||
-           (strcmp(lock->ref_name, lock->orig_ref_name) &&
-            log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0)) {
+       if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
                char *old_msg = strbuf_detach(err, NULL);
                strbuf_addf(err, "cannot update the ref '%s': %s",
                            lock->ref_name, old_msg);
@@ -2893,7 +2978,8 @@ static int commit_ref_update(struct ref_lock *lock,
                unlock_ref(lock);
                return -1;
        }
-       if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
+
+       if (strcmp(lock->ref_name, "HEAD") != 0) {
                /*
                 * Special hack: If a branch is updated directly and HEAD
                 * points to it (may happen on the remote side of a push
@@ -2909,6 +2995,7 @@ static int commit_ref_update(struct ref_lock *lock,
                unsigned char head_sha1[20];
                int head_flag;
                const char *head_ref;
+
                head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
                                              head_sha1, &head_flag);
                if (head_ref && (head_flag & REF_ISSYMREF) &&
@@ -2921,7 +3008,8 @@ static int commit_ref_update(struct ref_lock *lock,
                        }
                }
        }
-       if (!(flags & REF_LOG_ONLY) && commit_ref(lock)) {
+
+       if (commit_ref(lock)) {
                strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
                unlock_ref(lock);
                return -1;
@@ -3026,7 +3114,6 @@ int set_worktree_head_symref(const char *gitdir, const char *target)
        lock = xcalloc(1, sizeof(struct ref_lock));
        lock->lk = &head_lock;
        lock->ref_name = xstrdup(head_rel);
-       lock->orig_ref_name = xstrdup(head_rel);
 
        ret = create_symref_locked(lock, head_rel, target, NULL);
 
@@ -3205,60 +3292,88 @@ int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_dat
        strbuf_release(&sb);
        return ret;
 }
-/*
- * Call fn for each reflog in the namespace indicated by name.  name
- * must be empty or end with '/'.  Name will be used as a scratch
- * space, but its contents will be restored before return.
- */
-static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
-{
-       DIR *d = opendir(git_path("logs/%s", name->buf));
-       int retval = 0;
-       struct dirent *de;
-       int oldlen = name->len;
 
-       if (!d)
-               return name->len ? errno : 0;
+struct files_reflog_iterator {
+       struct ref_iterator base;
 
-       while ((de = readdir(d)) != NULL) {
-               struct stat st;
+       struct dir_iterator *dir_iterator;
+       struct object_id oid;
+};
 
-               if (de->d_name[0] == '.')
+static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
+{
+       struct files_reflog_iterator *iter =
+               (struct files_reflog_iterator *)ref_iterator;
+       struct dir_iterator *diter = iter->dir_iterator;
+       int ok;
+
+       while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
+               int flags;
+
+               if (!S_ISREG(diter->st.st_mode))
                        continue;
-               if (ends_with(de->d_name, ".lock"))
+               if (diter->basename[0] == '.')
+                       continue;
+               if (ends_with(diter->basename, ".lock"))
                        continue;
-               strbuf_addstr(name, de->d_name);
-               if (stat(git_path("logs/%s", name->buf), &st) < 0) {
-                       ; /* silently ignore */
-               } else {
-                       if (S_ISDIR(st.st_mode)) {
-                               strbuf_addch(name, '/');
-                               retval = do_for_each_reflog(name, fn, cb_data);
-                       } else {
-                               struct object_id oid;
 
-                               if (read_ref_full(name->buf, 0, oid.hash, NULL))
-                                       retval = error("bad ref for %s", name->buf);
-                               else
-                                       retval = fn(name->buf, &oid, 0, cb_data);
-                       }
-                       if (retval)
-                               break;
+               if (read_ref_full(diter->relative_path, 0,
+                                 iter->oid.hash, &flags)) {
+                       error("bad ref for %s", diter->path.buf);
+                       continue;
                }
-               strbuf_setlen(name, oldlen);
+
+               iter->base.refname = diter->relative_path;
+               iter->base.oid = &iter->oid;
+               iter->base.flags = flags;
+               return ITER_OK;
        }
-       closedir(d);
-       return retval;
+
+       iter->dir_iterator = NULL;
+       if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
+               ok = ITER_ERROR;
+       return ok;
+}
+
+static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
+                                  struct object_id *peeled)
+{
+       die("BUG: ref_iterator_peel() called for reflog_iterator");
+}
+
+static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
+{
+       struct files_reflog_iterator *iter =
+               (struct files_reflog_iterator *)ref_iterator;
+       int ok = ITER_DONE;
+
+       if (iter->dir_iterator)
+               ok = dir_iterator_abort(iter->dir_iterator);
+
+       base_ref_iterator_free(ref_iterator);
+       return ok;
+}
+
+static struct ref_iterator_vtable files_reflog_iterator_vtable = {
+       files_reflog_iterator_advance,
+       files_reflog_iterator_peel,
+       files_reflog_iterator_abort
+};
+
+struct ref_iterator *files_reflog_iterator_begin(void)
+{
+       struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
+       struct ref_iterator *ref_iterator = &iter->base;
+
+       base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
+       iter->dir_iterator = dir_iterator_begin(git_path("logs"));
+       return ref_iterator;
 }
 
 int for_each_reflog(each_ref_fn fn, void *cb_data)
 {
-       int retval;
-       struct strbuf name;
-       strbuf_init(&name, PATH_MAX);
-       retval = do_for_each_reflog(&name, fn, cb_data);
-       strbuf_release(&name);
-       return retval;
+       return do_for_each_ref_iterator(files_reflog_iterator_begin(),
+                                       fn, cb_data);
 }
 
 static int ref_update_reject_duplicates(struct string_list *refnames,
@@ -3402,6 +3517,38 @@ static const char *original_update_refname(struct ref_update *update)
        return update->refname;
 }
 
+/*
+ * Check whether the REF_HAVE_OLD and old_oid values stored in update
+ * are consistent with oid, which is the reference's current value. If
+ * everything is OK, return 0; otherwise, write an error message to
+ * err and return -1.
+ */
+static int check_old_oid(struct ref_update *update, struct object_id *oid,
+                        struct strbuf *err)
+{
+       if (!(update->flags & REF_HAVE_OLD) ||
+                  !hashcmp(oid->hash, update->old_sha1))
+               return 0;
+
+       if (is_null_sha1(update->old_sha1))
+               strbuf_addf(err, "cannot lock ref '%s': "
+                           "reference already exists",
+                           original_update_refname(update));
+       else if (is_null_oid(oid))
+               strbuf_addf(err, "cannot lock ref '%s': "
+                           "reference is missing but expected %s",
+                           original_update_refname(update),
+                           sha1_to_hex(update->old_sha1));
+       else
+               strbuf_addf(err, "cannot lock ref '%s': "
+                           "is at %s but expected %s",
+                           original_update_refname(update),
+                           oid_to_hex(oid),
+                           sha1_to_hex(update->old_sha1));
+
+       return -1;
+}
+
 /*
  * Prepare for carrying out update:
  * - Lock the reference referred to by update.
@@ -3447,7 +3594,7 @@ static int lock_ref_for_update(struct ref_update *update,
 
                reason = strbuf_detach(err, NULL);
                strbuf_addf(err, "cannot lock ref '%s': %s",
-                           update->refname, reason);
+                           original_update_refname(update), reason);
                free(reason);
                return ret;
        }
@@ -3461,28 +3608,17 @@ static int lock_ref_for_update(struct ref_update *update,
                         * the transaction, so we have to read it here
                         * to record and possibly check old_sha1:
                         */
-                       if (read_ref_full(update->refname,
-                                         mustexist ? RESOLVE_REF_READING : 0,
+                       if (read_ref_full(referent.buf, 0,
                                          lock->old_oid.hash, NULL)) {
                                if (update->flags & REF_HAVE_OLD) {
                                        strbuf_addf(err, "cannot lock ref '%s': "
-                                                   "can't resolve old value",
-                                                   update->refname);
-                                       return TRANSACTION_GENERIC_ERROR;
-                               } else {
-                                       hashclr(lock->old_oid.hash);
+                                                   "error reading reference",
+                                                   original_update_refname(update));
+                                       return -1;
                                }
-                       }
-                       if ((update->flags & REF_HAVE_OLD) &&
-                           hashcmp(lock->old_oid.hash, update->old_sha1)) {
-                               strbuf_addf(err, "cannot lock ref '%s': "
-                                           "is at %s but expected %s",
-                                           update->refname,
-                                           sha1_to_hex(lock->old_oid.hash),
-                                           sha1_to_hex(update->old_sha1));
+                       } else if (check_old_oid(update, &lock->old_oid, err)) {
                                return TRANSACTION_GENERIC_ERROR;
                        }
-
                } else {
                        /*
                         * Create a new update for the reference this
@@ -3499,6 +3635,9 @@ static int lock_ref_for_update(struct ref_update *update,
        } else {
                struct ref_update *parent_update;
 
+               if (check_old_oid(update, &lock->old_oid, err))
+                       return TRANSACTION_GENERIC_ERROR;
+
                /*
                 * If this update is happening indirectly because of a
                 * symref update, record the old SHA-1 in the parent
@@ -3509,20 +3648,6 @@ static int lock_ref_for_update(struct ref_update *update,
                     parent_update = parent_update->parent_update) {
                        oidcpy(&parent_update->lock->old_oid, &lock->old_oid);
                }
-
-               if ((update->flags & REF_HAVE_OLD) &&
-                   hashcmp(lock->old_oid.hash, update->old_sha1)) {
-                       if (is_null_sha1(update->old_sha1))
-                               strbuf_addf(err, "cannot lock ref '%s': reference already exists",
-                                           original_update_refname(update));
-                       else
-                               strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
-                                           original_update_refname(update),
-                                           sha1_to_hex(lock->old_oid.hash),
-                                           sha1_to_hex(update->old_sha1));
-
-                       return TRANSACTION_GENERIC_ERROR;
-               }
        }
 
        if ((update->flags & REF_HAVE_NEW) &&
@@ -3544,7 +3669,7 @@ static int lock_ref_for_update(struct ref_update *update,
                         */
                        update->lock = NULL;
                        strbuf_addf(err,
-                                   "cannot update the ref '%s': %s",
+                                   "cannot update ref '%s': %s",
                                    update->refname, write_err);
                        free(write_err);
                        return TRANSACTION_GENERIC_ERROR;