.mailmap: Combine more (email, name) to individual persons
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index 717aa54c039a4fc33357e0862bc28175bef017f4..43022066499ffaf828ac31e82b77f53539bc232d 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -3,6 +3,7 @@
 #include "object.h"
 #include "tag.h"
 #include "dir.h"
+#include "string-list.h"
 
 /*
  * Make sure "ref" is something reasonable to have under ".git/refs/";
@@ -71,6 +72,10 @@ int check_refname_format(const char *refname, int flags)
 {
        int component_len, component_count = 0;
 
+       if (!strcmp(refname, "@"))
+               /* Refname is a single character '@'. */
+               return -1;
+
        while (1) {
                /* We are at the start of a path component. */
                component_len = check_refname_component(refname, flags);
@@ -356,14 +361,12 @@ struct string_slice {
 
 static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 {
-       struct string_slice *key = (struct string_slice *)key_;
-       struct ref_entry *ent = *(struct ref_entry **)ent_;
-       int entlen = strlen(ent->name);
-       int cmplen = key->len < entlen ? key->len : entlen;
-       int cmp = memcmp(key->str, ent->name, cmplen);
+       const struct string_slice *key = key_;
+       const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
+       int cmp = strncmp(key->str, ent->name, key->len);
        if (cmp)
                return cmp;
-       return key->len - entlen;
+       return '\0' - (unsigned char)ent->name[key->len];
 }
 
 /*
@@ -746,6 +749,21 @@ static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
        }
 }
 
+/*
+ * 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
+ * through all of the sub-directories. We do not even need to care about
+ * sorting, as traversal order does not matter to us.
+ */
+static void prime_ref_dir(struct ref_dir *dir)
+{
+       int i;
+       for (i = 0; i < dir->nr; i++) {
+               struct ref_entry *entry = dir->entries[i];
+               if (entry->flag & REF_DIR)
+                       prime_ref_dir(get_ref_dir(entry));
+       }
+}
 /*
  * Return true iff refname1 and refname2 conflict with each other.
  * Two reference names conflict if one of them exactly matches the
@@ -803,6 +821,30 @@ static int is_refname_available(const char *refname, const char *oldrefname,
        return 1;
 }
 
+struct packed_ref_cache {
+       struct ref_entry *root;
+
+       /*
+        * Count of references to the data structure in this instance,
+        * including the pointer from ref_cache::packed if any.  The
+        * data will not be freed as long as the reference count is
+        * nonzero.
+        */
+       unsigned int referrers;
+
+       /*
+        * Iff the packed-refs file associated with this instance is
+        * currently locked for writing, this points at the associated
+        * lock (which is owned by somebody else).  The referrer count
+        * is also incremented when the file is locked and decremented
+        * when it is unlocked.
+        */
+       struct lock_file *lock;
+
+       /* The metadata from when this packed-refs cache was read */
+       struct stat_validity validity;
+};
+
 /*
  * Future: need to be in "struct repository"
  * when doing a full libification.
@@ -810,16 +852,51 @@ static int is_refname_available(const char *refname, const char *oldrefname,
 static struct ref_cache {
        struct ref_cache *next;
        struct ref_entry *loose;
-       struct ref_entry *packed;
-       /* The submodule name, or "" for the main repo. */
-       char name[FLEX_ARRAY];
-} *ref_cache;
+       struct packed_ref_cache *packed;
+       /*
+        * The submodule name, or "" for the main repo.  We allocate
+        * length 1 rather than FLEX_ARRAY so that the main ref_cache
+        * is initialized correctly.
+        */
+       char name[1];
+} ref_cache, *submodule_ref_caches;
+
+/* Lock used for the main packed-refs file: */
+static struct lock_file packlock;
+
+/*
+ * Increment the reference count of *packed_refs.
+ */
+static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
+{
+       packed_refs->referrers++;
+}
+
+/*
+ * Decrease the reference count of *packed_refs.  If it goes to zero,
+ * free *packed_refs and return true; otherwise return false.
+ */
+static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
+{
+       if (!--packed_refs->referrers) {
+               free_ref_entry(packed_refs->root);
+               stat_validity_clear(&packed_refs->validity);
+               free(packed_refs);
+               return 1;
+       } else {
+               return 0;
+       }
+}
 
 static void clear_packed_ref_cache(struct ref_cache *refs)
 {
        if (refs->packed) {
-               free_ref_entry(refs->packed);
+               struct packed_ref_cache *packed_refs = refs->packed;
+
+               if (packed_refs->lock)
+                       die("internal error: packed-ref cache cleared while locked");
                refs->packed = NULL;
+               release_packed_ref_cache(packed_refs);
        }
 }
 
@@ -851,18 +928,18 @@ static struct ref_cache *create_ref_cache(const char *submodule)
  */
 static struct ref_cache *get_ref_cache(const char *submodule)
 {
-       struct ref_cache *refs = ref_cache;
-       if (!submodule)
-               submodule = "";
-       while (refs) {
+       struct ref_cache *refs;
+
+       if (!submodule || !*submodule)
+               return &ref_cache;
+
+       for (refs = submodule_ref_caches; refs; refs = refs->next)
                if (!strcmp(submodule, refs->name))
                        return refs;
-               refs = refs->next;
-       }
 
        refs = create_ref_cache(submodule);
-       refs->next = ref_cache;
-       ref_cache = refs;
+       refs->next = submodule_ref_caches;
+       submodule_ref_caches = refs;
        return refs;
 }
 
@@ -989,30 +1066,58 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
        }
 }
 
-static struct ref_dir *get_packed_refs(struct ref_cache *refs)
+/*
+ * Get the packed_ref_cache for the specified ref_cache, creating it
+ * if necessary.
+ */
+static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
 {
+       const char *packed_refs_file;
+
+       if (*refs->name)
+               packed_refs_file = git_path_submodule(refs->name, "packed-refs");
+       else
+               packed_refs_file = git_path("packed-refs");
+
+       if (refs->packed &&
+           !stat_validity_check(&refs->packed->validity, packed_refs_file))
+               clear_packed_ref_cache(refs);
+
        if (!refs->packed) {
-               const char *packed_refs_file;
                FILE *f;
 
-               refs->packed = create_dir_entry(refs, "", 0, 0);
-               if (*refs->name)
-                       packed_refs_file = git_path_submodule(refs->name, "packed-refs");
-               else
-                       packed_refs_file = git_path("packed-refs");
+               refs->packed = xcalloc(1, sizeof(*refs->packed));
+               acquire_packed_ref_cache(refs->packed);
+               refs->packed->root = create_dir_entry(refs, "", 0, 0);
                f = fopen(packed_refs_file, "r");
                if (f) {
-                       read_packed_refs(f, get_ref_dir(refs->packed));
+                       stat_validity_update(&refs->packed->validity, fileno(f));
+                       read_packed_refs(f, get_ref_dir(refs->packed->root));
                        fclose(f);
                }
        }
-       return get_ref_dir(refs->packed);
+       return refs->packed;
+}
+
+static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
+{
+       return get_ref_dir(packed_ref_cache->root);
+}
+
+static struct ref_dir *get_packed_refs(struct ref_cache *refs)
+{
+       return get_packed_ref_dir(get_packed_ref_cache(refs));
 }
 
 void add_packed_ref(const char *refname, const unsigned char *sha1)
 {
-       add_ref(get_packed_refs(get_ref_cache(NULL)),
-                       create_ref_entry(refname, sha1, REF_ISPACKED, 1));
+       struct packed_ref_cache *packed_ref_cache =
+               get_packed_ref_cache(&ref_cache);
+
+       if (!packed_ref_cache->lock)
+               die("internal error: packed refs not locked");
+       add_ref(get_packed_ref_dir(packed_ref_cache),
+               create_ref_entry(refname, sha1, REF_ISPACKED, 1));
 }
 
 /*
@@ -1187,7 +1292,38 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sh
  */
 static struct ref_entry *get_packed_ref(const char *refname)
 {
-       return find_ref(get_packed_refs(get_ref_cache(NULL)), refname);
+       return find_ref(get_packed_refs(&ref_cache), refname);
+}
+
+/*
+ * A loose ref file doesn't exist; check for a packed ref.  The
+ * options are forwarded from resolve_safe_unsafe().
+ */
+static const char *handle_missing_loose_ref(const char *refname,
+                                           unsigned char *sha1,
+                                           int reading,
+                                           int *flag)
+{
+       struct ref_entry *entry;
+
+       /*
+        * The loose reference file does not exist; check for a packed
+        * reference.
+        */
+       entry = get_packed_ref(refname);
+       if (entry) {
+               hashcpy(sha1, entry->u.value.sha1);
+               if (flag)
+                       *flag |= REF_ISPACKED;
+               return refname;
+       }
+       /* The reference is not a packed reference, either. */
+       if (reading) {
+               return NULL;
+       } else {
+               hashclr(sha1);
+               return refname;
+       }
 }
 
 const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
@@ -1214,36 +1350,34 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
 
                git_snpath(path, sizeof(path), "%s", refname);
 
+               /*
+                * We might have to loop back here to avoid a race
+                * condition: first we lstat() the file, then we try
+                * to read it as a link or as a file.  But if somebody
+                * changes the type of the file (file <-> directory
+                * <-> symlink) between the lstat() and reading, then
+                * we don't want to report that as an error but rather
+                * try again starting with the lstat().
+                */
+       stat_ref:
                if (lstat(path, &st) < 0) {
-                       struct ref_entry *entry;
-
-                       if (errno != ENOENT)
-                               return NULL;
-                       /*
-                        * The loose reference file does not exist;
-                        * check for a packed reference.
-                        */
-                       entry = get_packed_ref(refname);
-                       if (entry) {
-                               hashcpy(sha1, entry->u.value.sha1);
-                               if (flag)
-                                       *flag |= REF_ISPACKED;
-                               return refname;
-                       }
-                       /* The reference is not a packed reference, either. */
-                       if (reading) {
+                       if (errno == ENOENT)
+                               return handle_missing_loose_ref(refname, sha1,
+                                                               reading, flag);
+                       else
                                return NULL;
-                       } else {
-                               hashclr(sha1);
-                               return refname;
-                       }
                }
 
                /* Follow "normalized" - ie "refs/.." symlinks by hand */
                if (S_ISLNK(st.st_mode)) {
                        len = readlink(path, buffer, sizeof(buffer)-1);
-                       if (len < 0)
-                               return NULL;
+                       if (len < 0) {
+                               if (errno == ENOENT || errno == EINVAL)
+                                       /* inconsistent with lstat; retry */
+                                       goto stat_ref;
+                               else
+                                       return NULL;
+                       }
                        buffer[len] = 0;
                        if (!prefixcmp(buffer, "refs/") &&
                                        !check_refname_format(buffer, 0)) {
@@ -1266,8 +1400,13 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                 * a ref
                 */
                fd = open(path, O_RDONLY);
-               if (fd < 0)
-                       return NULL;
+               if (fd < 0) {
+                       if (errno == ENOENT)
+                               /* inconsistent with lstat; retry */
+                               goto stat_ref;
+                       else
+                               return NULL;
+               }
                len = read_in_full(fd, buffer, sizeof(buffer)-1);
                close(fd);
                if (len < 0)
@@ -1279,8 +1418,19 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                /*
                 * Is it a symbolic ref?
                 */
-               if (prefixcmp(buffer, "ref:"))
-                       break;
+               if (prefixcmp(buffer, "ref:")) {
+                       /*
+                        * Please note that FETCH_HEAD has a second
+                        * line containing other data.
+                        */
+                       if (get_sha1_hex(buffer, sha1) ||
+                           (buffer[40] != '\0' && !isspace(buffer[40]))) {
+                               if (flag)
+                                       *flag |= REF_ISBROKEN;
+                               return NULL;
+                       }
+                       return refname;
+               }
                if (flag)
                        *flag |= REF_ISSYMREF;
                buf = buffer + 4;
@@ -1293,13 +1443,6 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                }
                refname = strcpy(refname_buffer, buf);
        }
-       /* Please note that FETCH_HEAD has a second line containing other data. */
-       if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
-               if (flag)
-                       *flag |= REF_ISBROKEN;
-               return NULL;
-       }
-       return refname;
 }
 
 char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
@@ -1504,24 +1647,41 @@ void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 }
 
 /*
- * Call fn for each reference in the specified submodule, omitting
+ * 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(const char *submodule, const char *base,
+static int do_for_each_entry(struct ref_cache *refs, const char *base,
                             each_ref_entry_fn fn, void *cb_data)
 {
-       struct ref_cache *refs = get_ref_cache(submodule);
-       struct ref_dir *packed_dir = get_packed_refs(refs);
-       struct ref_dir *loose_dir = get_loose_refs(refs);
+       struct packed_ref_cache *packed_ref_cache;
+       struct ref_dir *loose_dir;
+       struct ref_dir *packed_dir;
        int retval = 0;
 
+       /*
+        * 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) {
-               packed_dir = find_containing_dir(packed_dir, base, 0);
                loose_dir = find_containing_dir(loose_dir, base, 0);
        }
+       if (loose_dir)
+               prime_ref_dir(loose_dir);
+
+       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);
@@ -1538,11 +1698,12 @@ static int do_for_each_entry(const char *submodule, const char *base,
                                loose_dir, 0, fn, cb_data);
        }
 
+       release_packed_ref_cache(packed_ref_cache);
        return retval;
 }
 
 /*
- * Call fn for each reference in the specified submodule for which the
+ * 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
@@ -1550,8 +1711,8 @@ static int do_for_each_entry(const char *submodule, const char *base,
  * value, stop the iteration and return that value; otherwise, return
  * 0.
  */
-static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
-                          int trim, int flags, void *cb_data)
+static int do_for_each_ref(struct ref_cache *refs, const char *base,
+                          each_ref_fn fn, int trim, int flags, void *cb_data)
 {
        struct ref_entry_cb data;
        data.base = base;
@@ -1560,7 +1721,7 @@ static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn
        data.fn = fn;
        data.cb_data = cb_data;
 
-       return do_for_each_entry(submodule, base, do_one_ref, &data);
+       return do_for_each_entry(refs, base, do_one_ref, &data);
 }
 
 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
@@ -1593,23 +1754,23 @@ int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
+       return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
 }
 
 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
+       return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
 }
 
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
+       return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
 }
 
 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
                each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
+       return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
 }
 
 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
@@ -1644,7 +1805,7 @@ int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *c
 
 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
+       return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
 }
 
 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
@@ -1667,7 +1828,7 @@ int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
        struct strbuf buf = STRBUF_INIT;
        int ret;
        strbuf_addf(&buf, "%srefs/", get_git_namespace());
-       ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
+       ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
        strbuf_release(&buf);
        return ret;
 }
@@ -1709,7 +1870,7 @@ int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 
 int for_each_rawref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref(NULL, "", fn, 0,
+       return do_for_each_ref(&ref_cache, "", fn, 0,
                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 
@@ -1915,7 +2076,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
         * name is a proper prefix of our refname.
         */
        if (missing &&
-            !is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
+            !is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {
                last_errno = ENOTDIR;
                goto error_return;
        }
@@ -1992,6 +2153,73 @@ static void write_packed_entry(int fd, char *refname, unsigned char *sha1,
        }
 }
 
+/*
+ * An each_ref_entry_fn that writes the entry to a packed-refs file.
+ */
+static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
+{
+       int *fd = cb_data;
+       enum peel_status peel_status = peel_entry(entry, 0);
+
+       if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
+               error("internal error: %s is not a valid packed reference!",
+                     entry->name);
+       write_packed_entry(*fd, entry->name, entry->u.value.sha1,
+                          peel_status == PEEL_PEELED ?
+                          entry->u.value.peeled : NULL);
+       return 0;
+}
+
+int lock_packed_refs(int flags)
+{
+       struct packed_ref_cache *packed_ref_cache;
+
+       /* Discard the old cache because it might be invalid: */
+       clear_packed_ref_cache(&ref_cache);
+       if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
+               return -1;
+       /* Read the current packed-refs while holding the lock: */
+       packed_ref_cache = get_packed_ref_cache(&ref_cache);
+       packed_ref_cache->lock = &packlock;
+       /* Increment the reference count to prevent it from being freed: */
+       acquire_packed_ref_cache(packed_ref_cache);
+       return 0;
+}
+
+int commit_packed_refs(void)
+{
+       struct packed_ref_cache *packed_ref_cache =
+               get_packed_ref_cache(&ref_cache);
+       int error = 0;
+
+       if (!packed_ref_cache->lock)
+               die("internal error: packed-refs not locked");
+       write_or_die(packed_ref_cache->lock->fd,
+                    PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
+
+       do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
+                                0, write_packed_entry_fn,
+                                &packed_ref_cache->lock->fd);
+       if (commit_lock_file(packed_ref_cache->lock))
+               error = -1;
+       packed_ref_cache->lock = NULL;
+       release_packed_ref_cache(packed_ref_cache);
+       return error;
+}
+
+void rollback_packed_refs(void)
+{
+       struct packed_ref_cache *packed_ref_cache =
+               get_packed_ref_cache(&ref_cache);
+
+       if (!packed_ref_cache->lock)
+               die("internal error: packed-refs not locked");
+       rollback_lock_file(packed_ref_cache->lock);
+       packed_ref_cache->lock = NULL;
+       release_packed_ref_cache(packed_ref_cache);
+       clear_packed_ref_cache(&ref_cache);
+}
+
 struct ref_to_prune {
        struct ref_to_prune *next;
        unsigned char sha1[20];
@@ -2000,35 +2228,50 @@ struct ref_to_prune {
 
 struct pack_refs_cb_data {
        unsigned int flags;
+       struct ref_dir *packed_refs;
        struct ref_to_prune *ref_to_prune;
-       int fd;
 };
 
-static int pack_one_ref(struct ref_entry *entry, void *cb_data)
+/*
+ * An each_ref_entry_fn that is run over loose references only.  If
+ * the loose reference can be packed, add an entry in the packed ref
+ * cache.  If the reference should be pruned, also add it to
+ * ref_to_prune in the pack_refs_cb_data.
+ */
+static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
 {
        struct pack_refs_cb_data *cb = cb_data;
        enum peel_status peel_status;
+       struct ref_entry *packed_entry;
        int is_tag_ref = !prefixcmp(entry->name, "refs/tags/");
 
-       /* ALWAYS pack refs that were already packed or are tags */
-       if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref &&
-           !(entry->flag & REF_ISPACKED))
+       /* ALWAYS pack tags */
+       if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
                return 0;
 
        /* Do not pack symbolic or broken refs: */
        if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
                return 0;
 
+       /* Add a packed ref cache entry equivalent to the loose entry. */
        peel_status = peel_entry(entry, 1);
        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
                die("internal error peeling reference %s (%s)",
                    entry->name, sha1_to_hex(entry->u.value.sha1));
-       write_packed_entry(cb->fd, entry->name, entry->u.value.sha1,
-                          peel_status == PEEL_PEELED ?
-                          entry->u.value.peeled : NULL);
+       packed_entry = find_ref(cb->packed_refs, entry->name);
+       if (packed_entry) {
+               /* Overwrite existing packed entry with info from loose entry */
+               packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
+               hashcpy(packed_entry->u.value.sha1, entry->u.value.sha1);
+       } else {
+               packed_entry = create_ref_entry(entry->name, entry->u.value.sha1,
+                                               REF_ISPACKED | REF_KNOWS_PEELED, 0);
+               add_ref(cb->packed_refs, packed_entry);
+       }
+       hashcpy(packed_entry->u.value.peeled, entry->u.value.peeled);
 
-       /* If the ref was already packed, there is no need to prune it. */
-       if ((cb->flags & PACK_REFS_PRUNE) && !(entry->flag & REF_ISPACKED)) {
+       /* Schedule the loose reference for pruning if requested. */
+       if ((cb->flags & PACK_REFS_PRUNE)) {
                int namelen = strlen(entry->name) + 1;
                struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
                hashcpy(n->sha1, entry->u.value.sha1);
@@ -2090,8 +2333,6 @@ static void prune_refs(struct ref_to_prune *r)
        }
 }
 
-static struct lock_file packlock;
-
 int pack_refs(unsigned int flags)
 {
        struct pack_refs_cb_data cbdata;
@@ -2099,26 +2340,38 @@ int pack_refs(unsigned int flags)
        memset(&cbdata, 0, sizeof(cbdata));
        cbdata.flags = flags;
 
-       cbdata.fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"),
-                                             LOCK_DIE_ON_ERROR);
+       lock_packed_refs(LOCK_DIE_ON_ERROR);
+       cbdata.packed_refs = get_packed_refs(&ref_cache);
 
-       write_or_die(cbdata.fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
+       do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
+                                pack_if_possible_fn, &cbdata);
 
-       do_for_each_entry(NULL, "", pack_one_ref, &cbdata);
-       if (commit_lock_file(&packlock) < 0)
+       if (commit_packed_refs())
                die_errno("unable to overwrite old ref-pack file");
+
        prune_refs(cbdata.ref_to_prune);
        return 0;
 }
 
-static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
+/*
+ * If entry is no longer needed in packed-refs, add it to the string
+ * list pointed to by cb_data.  Reasons for deleting entries:
+ *
+ * - Entry is broken.
+ * - Entry is overridden by a loose ref.
+ * - Entry does not point at a valid object.
+ *
+ * In the first and third cases, also emit an error message because these
+ * are indications of repository corruption.
+ */
+static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
 {
-       int *fd = cb_data;
-       enum peel_status peel_status;
+       struct string_list *refs_to_delete = cb_data;
 
        if (entry->flag & REF_ISBROKEN) {
                /* This shouldn't happen to packed refs. */
                error("%s is broken!", entry->name);
+               string_list_append(refs_to_delete, entry->name);
                return 0;
        }
        if (!has_sha1_file(entry->u.value.sha1)) {
@@ -2128,7 +2381,7 @@ static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
                if (read_ref_full(entry->name, sha1, 0, &flags))
                        /* We should at least have found the packed ref. */
                        die("Internal error");
-               if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED))
+               if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
                        /*
                         * This packed reference is overridden by a
                         * loose reference, so it is OK that its value
@@ -2137,9 +2390,11 @@ static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
                         * collected.  For this purpose we don't even
                         * care whether the loose reference itself is
                         * invalid, broken, symbolic, etc.  Silently
-                        * omit the packed reference from the output.
+                        * remove the packed reference.
                         */
+                       string_list_append(refs_to_delete, entry->name);
                        return 0;
+               }
                /*
                 * There is no overriding loose reference, so the fact
                 * that this reference doesn't refer to a valid object
@@ -2148,45 +2403,47 @@ static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
                 * the output.
                 */
                error("%s does not point to a valid object!", entry->name);
+               string_list_append(refs_to_delete, entry->name);
                return 0;
        }
 
-       peel_status = peel_entry(entry, 0);
-       write_packed_entry(*fd, entry->name, entry->u.value.sha1,
-                          peel_status == PEEL_PEELED ?
-                          entry->u.value.peeled : NULL);
-
        return 0;
 }
 
 static int repack_without_ref(const char *refname)
 {
-       int fd;
-       struct ref_cache *refs = get_ref_cache(NULL);
        struct ref_dir *packed;
+       struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
+       struct string_list_item *ref_to_delete;
 
        if (!get_packed_ref(refname))
                return 0; /* refname does not exist in packed refs */
 
-       fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
-       if (fd < 0) {
+       if (lock_packed_refs(0)) {
                unable_to_lock_error(git_path("packed-refs"), errno);
                return error("cannot delete '%s' from packed refs", refname);
        }
-       clear_packed_ref_cache(refs);
-       packed = get_packed_refs(refs);
-       /* Remove refname from the cache. */
+       packed = get_packed_refs(&ref_cache);
+
+       /* Remove refname from the cache: */
        if (remove_entry(packed, refname) == -1) {
                /*
                 * The packed entry disappeared while we were
                 * acquiring the lock.
                 */
-               rollback_lock_file(&packlock);
+               rollback_packed_refs();
                return 0;
        }
-       write_or_die(fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
-       do_for_each_entry_in_dir(packed, 0, repack_ref_fn, &fd);
-       return commit_lock_file(&packlock);
+
+       /* Remove any other accumulated cruft: */
+       do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
+       for_each_string_list_item(ref_to_delete, &refs_to_delete) {
+               if (remove_entry(packed, ref_to_delete->string) == -1)
+                       die("internal error");
+       }
+
+       /* Write what remains: */
+       return commit_packed_refs();
 }
 
 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
@@ -2214,7 +2471,7 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
        ret |= repack_without_ref(lock->ref_name);
 
        unlink_or_warn(git_path("logs/%s", lock->ref_name));
-       clear_loose_ref_cache(get_ref_cache(NULL));
+       clear_loose_ref_cache(&ref_cache);
        unlock_ref(lock);
        return ret;
 }
@@ -2236,7 +2493,6 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        struct stat loginfo;
        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
        const char *symref = NULL;
-       struct ref_cache *refs = get_ref_cache(NULL);
 
        if (log && S_ISLNK(loginfo.st_mode))
                return error("reflog for %s is a symlink", oldrefname);
@@ -2248,10 +2504,10 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        if (!symref)
                return error("refname %s not found", oldrefname);
 
-       if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
+       if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
                return 1;
 
-       if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
+       if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
                return 1;
 
        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
@@ -2507,7 +2763,7 @@ int write_ref_sha1(struct ref_lock *lock,
                unlock_ref(lock);
                return -1;
        }
-       clear_loose_ref_cache(get_ref_cache(NULL));
+       clear_loose_ref_cache(&ref_cache);
        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
            (strcmp(lock->ref_name, lock->orig_ref_name) &&
             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
@@ -2723,59 +2979,117 @@ int read_ref_at(const char *refname, unsigned long at_time, int cnt,
        return 1;
 }
 
-int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
+static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
+{
+       unsigned char osha1[20], nsha1[20];
+       char *email_end, *message;
+       unsigned long timestamp;
+       int tz;
+
+       /* old SP new SP name <email> SP time TAB msg LF */
+       if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
+           get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
+           get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
+           !(email_end = strchr(sb->buf + 82, '>')) ||
+           email_end[1] != ' ' ||
+           !(timestamp = strtoul(email_end + 2, &message, 10)) ||
+           !message || message[0] != ' ' ||
+           (message[1] != '+' && message[1] != '-') ||
+           !isdigit(message[2]) || !isdigit(message[3]) ||
+           !isdigit(message[4]) || !isdigit(message[5]))
+               return 0; /* corrupt? */
+       email_end[1] = '\0';
+       tz = strtol(message + 1, NULL, 10);
+       if (message[6] != '\t')
+               message += 6;
+       else
+               message += 7;
+       return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
+}
+
+static char *find_beginning_of_line(char *bob, char *scan)
+{
+       while (bob < scan && *(--scan) != '\n')
+               ; /* keep scanning backwards */
+       /*
+        * Return either beginning of the buffer, or LF at the end of
+        * the previous line.
+        */
+       return scan;
+}
+
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
 {
-       const char *logfile;
-       FILE *logfp;
        struct strbuf sb = STRBUF_INIT;
-       int ret = 0;
+       FILE *logfp;
+       long pos;
+       int ret = 0, at_tail = 1;
 
-       logfile = git_path("logs/%s", refname);
-       logfp = fopen(logfile, "r");
+       logfp = fopen(git_path("logs/%s", refname), "r");
        if (!logfp)
                return -1;
 
-       if (ofs) {
-               struct stat statbuf;
-               if (fstat(fileno(logfp), &statbuf) ||
-                   statbuf.st_size < ofs ||
-                   fseek(logfp, -ofs, SEEK_END) ||
-                   strbuf_getwholeline(&sb, logfp, '\n')) {
-                       fclose(logfp);
-                       strbuf_release(&sb);
-                       return -1;
+       /* Jump to the end */
+       if (fseek(logfp, 0, SEEK_END) < 0)
+               return error("cannot seek back reflog for %s: %s",
+                            refname, strerror(errno));
+       pos = ftell(logfp);
+       while (!ret && 0 < pos) {
+               int cnt;
+               size_t nread;
+               char buf[BUFSIZ];
+               char *endp, *scanp;
+
+               /* Fill next block from the end */
+               cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
+               if (fseek(logfp, pos - cnt, SEEK_SET))
+                       return error("cannot seek back reflog for %s: %s",
+                                    refname, strerror(errno));
+               nread = fread(buf, cnt, 1, logfp);
+               if (nread != 1)
+                       return error("cannot read %d bytes from reflog for %s: %s",
+                                    cnt, refname, strerror(errno));
+               pos -= cnt;
+
+               scanp = endp = buf + cnt;
+               if (at_tail && scanp[-1] == '\n')
+                       /* Looking at the final LF at the end of the file */
+                       scanp--;
+               at_tail = 0;
+
+               while (buf < scanp) {
+                       /*
+                        * terminating LF of the previous line, or the beginning
+                        * of the buffer.
+                        */
+                       char *bp;
+
+                       bp = find_beginning_of_line(buf, scanp);
+
+                       if (*bp != '\n') {
+                               strbuf_splice(&sb, 0, 0, buf, endp - buf);
+                               if (pos)
+                                       break; /* need to fill another block */
+                               scanp = buf - 1; /* leave loop */
+                       } else {
+                               /*
+                                * (bp + 1) thru endp is the beginning of the
+                                * current line we have in sb
+                                */
+                               strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
+                               scanp = bp;
+                               endp = bp + 1;
+                       }
+                       ret = show_one_reflog_ent(&sb, fn, cb_data);
+                       strbuf_reset(&sb);
+                       if (ret)
+                               break;
                }
-       }
 
-       while (!strbuf_getwholeline(&sb, logfp, '\n')) {
-               unsigned char osha1[20], nsha1[20];
-               char *email_end, *message;
-               unsigned long timestamp;
-               int tz;
-
-               /* old SP new SP name <email> SP time TAB msg LF */
-               if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
-                   get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
-                   get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
-                   !(email_end = strchr(sb.buf + 82, '>')) ||
-                   email_end[1] != ' ' ||
-                   !(timestamp = strtoul(email_end + 2, &message, 10)) ||
-                   !message || message[0] != ' ' ||
-                   (message[1] != '+' && message[1] != '-') ||
-                   !isdigit(message[2]) || !isdigit(message[3]) ||
-                   !isdigit(message[4]) || !isdigit(message[5]))
-                       continue; /* corrupt? */
-               email_end[1] = '\0';
-               tz = strtol(message + 1, NULL, 10);
-               if (message[6] != '\t')
-                       message += 6;
-               else
-                       message += 7;
-               ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
-                        cb_data);
-               if (ret)
-                       break;
        }
+       if (!ret && sb.len)
+               ret = show_one_reflog_ent(&sb, fn, cb_data);
+
        fclose(logfp);
        strbuf_release(&sb);
        return ret;
@@ -2783,9 +3097,20 @@ int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long
 
 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
 {
-       return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
-}
+       FILE *logfp;
+       struct strbuf sb = STRBUF_INIT;
+       int ret = 0;
 
+       logfp = fopen(git_path("logs/%s", refname), "r");
+       if (!logfp)
+               return -1;
+
+       while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
+               ret = show_one_reflog_ent(&sb, fn, cb_data);
+       fclose(logfp);
+       strbuf_release(&sb);
+       return ret;
+}
 /*
  * 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
@@ -2985,3 +3310,46 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
        free(short_name);
        return xstrdup(refname);
 }
+
+static struct string_list *hide_refs;
+
+int parse_hide_refs_config(const char *var, const char *value, const char *section)
+{
+       if (!strcmp("transfer.hiderefs", var) ||
+           /* NEEDSWORK: use parse_config_key() once both are merged */
+           (!prefixcmp(var, section) && var[strlen(section)] == '.' &&
+            !strcmp(var + strlen(section), ".hiderefs"))) {
+               char *ref;
+               int len;
+
+               if (!value)
+                       return config_error_nonbool(var);
+               ref = xstrdup(value);
+               len = strlen(ref);
+               while (len && ref[len - 1] == '/')
+                       ref[--len] = '\0';
+               if (!hide_refs) {
+                       hide_refs = xcalloc(1, sizeof(*hide_refs));
+                       hide_refs->strdup_strings = 1;
+               }
+               string_list_append(hide_refs, ref);
+       }
+       return 0;
+}
+
+int ref_is_hidden(const char *refname)
+{
+       struct string_list_item *item;
+
+       if (!hide_refs)
+               return 0;
+       for_each_string_list_item(item, hide_refs) {
+               int len;
+               if (prefixcmp(refname, item->string))
+                       continue;
+               len = strlen(item->string);
+               if (!refname[len] || refname[len] == '/')
+                       return 1;
+       }
+       return 0;
+}