Merge branch 'jk/push-simple' into maint
[gitweb.git] / refs.c
diff --git a/refs.c b/refs.c
index a77458f2f6eb108a90a1cf3d2cc4a771549c05f9..5ff457ebfce7aba9cd470f3e2e1f3f5dbe9d9741 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -70,16 +70,8 @@ static int check_refname_component(const char *refname, int flags)
 out:
        if (cp == refname)
                return 0; /* Component has zero length. */
-       if (refname[0] == '.') {
-               if (!(flags & REFNAME_DOT_COMPONENT))
-                       return -1; /* Component starts with '.'. */
-               /*
-                * Even if leading dots are allowed, don't allow "."
-                * as a component (".." is prevented by a rule above).
-                */
-               if (refname[1] == '\0')
-                       return -1; /* Component equals ".". */
-       }
+       if (refname[0] == '.')
+               return -1; /* Component starts with '.'. */
        if (cp - refname >= LOCK_SUFFIX_LEN &&
            !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
                return -1; /* Refname ends with ".lock". */
@@ -195,8 +187,8 @@ struct ref_dir {
 
 /*
  * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
- * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
- * refs.h.
+ * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
+ * public values; see refs.h.
  */
 
 /*
@@ -204,16 +196,16 @@ struct ref_dir {
  * the correct peeled value for the reference, which might be
  * null_sha1 if the reference is not a tag or if it is broken.
  */
-#define REF_KNOWS_PEELED 0x08
+#define REF_KNOWS_PEELED 0x10
 
 /* ref_entry represents a directory of references */
-#define REF_DIR 0x10
+#define REF_DIR 0x20
 
 /*
  * Entry has not yet been read from disk (used only for REF_DIR
  * entries representing loose references)
  */
-#define REF_INCOMPLETE 0x20
+#define REF_INCOMPLETE 0x40
 
 /*
  * A ref_entry represents either a reference or a "subdirectory" of
@@ -282,6 +274,39 @@ static struct ref_dir *get_ref_dir(struct ref_entry *entry)
        return dir;
 }
 
+/*
+ * Check if a refname is safe.
+ * For refs that start with "refs/" we consider it safe as long they do
+ * not try to resolve to outside of refs/.
+ *
+ * For all other refs we only consider them safe iff they only contain
+ * upper case characters and '_' (like "HEAD" AND "MERGE_HEAD", and not like
+ * "config").
+ */
+static int refname_is_safe(const char *refname)
+{
+       if (starts_with(refname, "refs/")) {
+               char *buf;
+               int result;
+
+               buf = xmalloc(strlen(refname) + 1);
+               /*
+                * Does the refname try to escape refs/?
+                * For example: refs/foo/../bar is safe but refs/foo/../../bar
+                * is not.
+                */
+               result = !normalize_path_copy(buf, refname + strlen("refs/"));
+               free(buf);
+               return result;
+       }
+       while (*refname) {
+               if (!isupper(*refname) && *refname != '_')
+                       return 0;
+               refname++;
+       }
+       return 1;
+}
+
 static struct ref_entry *create_ref_entry(const char *refname,
                                          const unsigned char *sha1, int flag,
                                          int check_name)
@@ -290,8 +315,10 @@ static struct ref_entry *create_ref_entry(const char *refname,
        struct ref_entry *ref;
 
        if (check_name &&
-           check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
+           check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
                die("Reference has invalid format: '%s'", refname);
+       if (!check_name && !refname_is_safe(refname))
+               die("Reference has invalid name: '%s'", refname);
        len = strlen(refname) + 1;
        ref = xmalloc(sizeof(struct ref_entry) + len);
        hashcpy(ref->u.value.sha1, sha1);
@@ -787,13 +814,13 @@ static void prime_ref_dir(struct ref_dir *dir)
        }
 }
 
-static int entry_matches(struct ref_entry *entry, const char *refname)
+static int entry_matches(struct ref_entry *entry, const struct string_list *list)
 {
-       return refname && !strcmp(entry->name, refname);
+       return list && string_list_has_string(list, entry->name);
 }
 
 struct nonmatching_ref_data {
-       const char *skip;
+       const struct string_list *skip;
        struct ref_entry *found;
 };
 
@@ -817,16 +844,19 @@ static void report_refname_conflict(struct ref_entry *entry,
 /*
  * Return true iff a reference named refname could be created without
  * conflicting with the name of an existing reference in dir.  If
- * oldrefname is non-NULL, ignore potential conflicts with oldrefname
- * (e.g., because oldrefname is scheduled for deletion in the same
+ * skip is non-NULL, ignore potential conflicts with refs in skip
+ * (e.g., because they are scheduled for deletion in the same
  * operation).
  *
  * Two reference names conflict if one of them exactly matches the
  * leading components of the other; e.g., "foo/bar" conflicts with
  * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
  * "foo/barbados".
+ *
+ * skip must be sorted.
  */
-static int is_refname_available(const char *refname, const char *oldrefname,
+static int is_refname_available(const char *refname,
+                               const struct string_list *skip,
                                struct ref_dir *dir)
 {
        const char *slash;
@@ -840,12 +870,12 @@ static int is_refname_available(const char *refname, const char *oldrefname,
                 * looking for a conflict with a leaf entry.
                 *
                 * If we find one, we still must make sure it is
-                * not "oldrefname".
+                * not in "skip".
                 */
                pos = search_ref_dir(dir, refname, slash - refname);
                if (pos >= 0) {
                        struct ref_entry *entry = dir->entries[pos];
-                       if (entry_matches(entry, oldrefname))
+                       if (entry_matches(entry, skip))
                                return 1;
                        report_refname_conflict(entry, refname);
                        return 0;
@@ -878,13 +908,13 @@ static int is_refname_available(const char *refname, const char *oldrefname,
                /*
                 * We found a directory named "refname". It is a
                 * problem iff it contains any ref that is not
-                * "oldrefname".
+                * in "skip".
                 */
                struct ref_entry *entry = dir->entries[pos];
                struct ref_dir *dir = get_ref_dir(entry);
                struct nonmatching_ref_data data;
 
-               data.skip = oldrefname;
+               data.skip = skip;
                sort_ref_dir(dir);
                if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data))
                        return 1;
@@ -1116,7 +1146,13 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
 
                refname = parse_ref_line(refline, sha1);
                if (refname) {
-                       last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
+                       int flag = REF_ISPACKED;
+
+                       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+                               hashclr(sha1);
+                               flag |= REF_BAD_NAME | REF_ISBROKEN;
+                       }
+                       last = create_ref_entry(refname, sha1, flag, 0);
                        if (peeled == PEELED_FULLY ||
                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
                                last->flag |= REF_KNOWS_PEELED;
@@ -1248,12 +1284,19 @@ static void read_loose_refs(const char *dirname, struct ref_dir *dir)
                                        hashclr(sha1);
                                        flag |= REF_ISBROKEN;
                                }
-                       } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
+                       } else if (read_ref_full(refname.buf,
+                                                RESOLVE_REF_READING,
+                                                sha1, &flag)) {
                                hashclr(sha1);
                                flag |= REF_ISBROKEN;
                        }
+                       if (check_refname_format(refname.buf,
+                                                REFNAME_ALLOW_ONELEVEL)) {
+                               hashclr(sha1);
+                               flag |= REF_BAD_NAME | REF_ISBROKEN;
+                       }
                        add_entry_to_dir(dir,
-                                        create_ref_entry(refname.buf, sha1, flag, 1));
+                                        create_ref_entry(refname.buf, sha1, flag, 0));
                }
                strbuf_setlen(&refname, dirnamelen);
        }
@@ -1372,10 +1415,10 @@ static struct ref_entry *get_packed_ref(const char *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)
+static int resolve_missing_loose_ref(const char *refname,
+                                    int resolve_flags,
+                                    unsigned char *sha1,
+                                    int *flags)
 {
        struct ref_entry *entry;
 
@@ -1386,35 +1429,51 @@ static const char *handle_missing_loose_ref(const char *refname,
        entry = get_packed_ref(refname);
        if (entry) {
                hashcpy(sha1, entry->u.value.sha1);
-               if (flag)
-                       *flag |= REF_ISPACKED;
-               return refname;
+               if (flags)
+                       *flags |= REF_ISPACKED;
+               return 0;
        }
        /* The reference is not a packed reference, either. */
-       if (reading) {
-               return NULL;
+       if (resolve_flags & RESOLVE_REF_READING) {
+               errno = ENOENT;
+               return -1;
        } else {
                hashclr(sha1);
-               return refname;
+               return 0;
        }
 }
 
 /* This function needs to return a meaningful errno on failure */
-const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
+const char *resolve_ref_unsafe(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 {
        int depth = MAXDEPTH;
        ssize_t len;
        char buffer[256];
        static char refname_buffer[256];
+       int bad_name = 0;
 
-       if (flag)
-               *flag = 0;
+       if (flags)
+               *flags = 0;
 
        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-               errno = EINVAL;
-               return NULL;
-       }
+               if (flags)
+                       *flags |= REF_BAD_NAME;
 
+               if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+                   !refname_is_safe(refname)) {
+                       errno = EINVAL;
+                       return NULL;
+               }
+               /*
+                * dwim_ref() uses REF_ISBROKEN to distinguish between
+                * missing refs and refs that were present but invalid,
+                * to complain about the latter to stderr.
+                *
+                * We don't know whether the ref exists, so don't set
+                * REF_ISBROKEN yet.
+                */
+               bad_name = 1;
+       }
        for (;;) {
                char path[PATH_MAX];
                struct stat st;
@@ -1439,11 +1498,17 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                 */
        stat_ref:
                if (lstat(path, &st) < 0) {
-                       if (errno == ENOENT)
-                               return handle_missing_loose_ref(refname, sha1,
-                                                               reading, flag);
-                       else
+                       if (errno != ENOENT)
+                               return NULL;
+                       if (resolve_missing_loose_ref(refname, resolve_flags,
+                                                     sha1, flags))
                                return NULL;
+                       if (bad_name) {
+                               hashclr(sha1);
+                               if (flags)
+                                       *flags |= REF_ISBROKEN;
+                       }
+                       return refname;
                }
 
                /* Follow "normalized" - ie "refs/.." symlinks by hand */
@@ -1461,8 +1526,12 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                                        !check_refname_format(buffer, 0)) {
                                strcpy(refname_buffer, buffer);
                                refname = refname_buffer;
-                               if (flag)
-                                       *flag |= REF_ISSYMREF;
+                               if (flags)
+                                       *flags |= REF_ISSYMREF;
+                               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+                                       hashclr(sha1);
+                                       return refname;
+                               }
                                continue;
                        }
                }
@@ -1507,31 +1576,45 @@ const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int rea
                         */
                        if (get_sha1_hex(buffer, sha1) ||
                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
-                               if (flag)
-                                       *flag |= REF_ISBROKEN;
+                               if (flags)
+                                       *flags |= REF_ISBROKEN;
                                errno = EINVAL;
                                return NULL;
                        }
+                       if (bad_name) {
+                               hashclr(sha1);
+                               if (flags)
+                                       *flags |= REF_ISBROKEN;
+                       }
                        return refname;
                }
-               if (flag)
-                       *flag |= REF_ISSYMREF;
+               if (flags)
+                       *flags |= REF_ISSYMREF;
                buf = buffer + 4;
                while (isspace(*buf))
                        buf++;
+               refname = strcpy(refname_buffer, buf);
+               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+                       hashclr(sha1);
+                       return refname;
+               }
                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
-                       if (flag)
-                               *flag |= REF_ISBROKEN;
-                       errno = EINVAL;
-                       return NULL;
+                       if (flags)
+                               *flags |= REF_ISBROKEN;
+
+                       if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+                           !refname_is_safe(buf)) {
+                               errno = EINVAL;
+                               return NULL;
+                       }
+                       bad_name = 1;
                }
-               refname = strcpy(refname_buffer, buf);
        }
 }
 
-char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
+char *resolve_refdup(const char *ref, int resolve_flags, unsigned char *sha1, int *flags)
 {
-       const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
+       const char *ret = resolve_ref_unsafe(ref, resolve_flags, sha1, flags);
        return ret ? xstrdup(ret) : NULL;
 }
 
@@ -1542,22 +1625,22 @@ struct ref_filter {
        void *cb_data;
 };
 
-int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
+int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 {
-       if (resolve_ref_unsafe(refname, sha1, reading, flags))
+       if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
                return 0;
        return -1;
 }
 
 int read_ref(const char *refname, unsigned char *sha1)
 {
-       return read_ref_full(refname, sha1, 1, NULL);
+       return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 }
 
 int ref_exists(const char *refname)
 {
        unsigned char sha1[20];
-       return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
+       return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 }
 
 static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
@@ -1670,7 +1753,7 @@ int peel_ref(const char *refname, unsigned char *sha1)
                return 0;
        }
 
-       if (read_ref_full(refname, base, 1, &flag))
+       if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
                return -1;
 
        /*
@@ -1711,7 +1794,7 @@ static int warn_if_dangling_symref(const char *refname, const unsigned char *sha
        if (!(flags & REF_ISSYMREF))
                return 0;
 
-       resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
+       resolves_to = resolve_ref_unsafe(refname, 0, junk, NULL);
        if (!resolves_to
            || (d->refname
                ? strcmp(resolves_to, d->refname)
@@ -1836,7 +1919,7 @@ static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
                return 0;
        }
 
-       if (!read_ref_full("HEAD", sha1, 1, &flag))
+       if (!read_ref_full("HEAD", RESOLVE_REF_READING, sha1, &flag))
                return fn("HEAD", sha1, flag, cb_data);
 
        return 0;
@@ -1916,7 +1999,7 @@ int head_ref_namespaced(each_ref_fn fn, void *cb_data)
        int flag;
 
        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
-       if (!read_ref_full(buf.buf, sha1, 1, &flag))
+       if (!read_ref_full(buf.buf, RESOLVE_REF_READING, sha1, &flag))
                ret = fn(buf.buf, sha1, flag, cb_data);
        strbuf_release(&buf);
 
@@ -2011,7 +2094,9 @@ int refname_match(const char *abbrev_name, const char *full_name)
 static struct ref_lock *verify_lock(struct ref_lock *lock,
        const unsigned char *old_sha1, int mustexist)
 {
-       if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
+       if (read_ref_full(lock->ref_name,
+                         mustexist ? RESOLVE_REF_READING : 0,
+                         lock->old_sha1, NULL)) {
                int save_errno = errno;
                error("Can't verify ref %s", lock->ref_name);
                unlock_ref(lock);
@@ -2084,7 +2169,8 @@ int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 
                this_result = refs_found ? sha1_from_ref : sha1;
                mksnpath(fullref, sizeof(fullref), *p, len, str);
-               r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
+               r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
+                                      this_result, &flag);
                if (r) {
                        if (!refs_found++)
                                *ref = xstrdup(r);
@@ -2113,7 +2199,8 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
                const char *ref, *it;
 
                mksnpath(path, sizeof(path), *p, len, str);
-               ref = resolve_ref_unsafe(path, hash, 1, NULL);
+               ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
+                                        hash, NULL);
                if (!ref)
                        continue;
                if (reflog_exists(path))
@@ -2134,11 +2221,12 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 }
 
 /*
- * Locks a "refs/" ref returning the lock on success and NULL on failure.
+ * 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(const char *refname,
                                            const unsigned char *old_sha1,
+                                           const struct string_list *skip,
                                            int flags, int *type_p)
 {
        char *ref_file;
@@ -2147,13 +2235,23 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        int last_errno = 0;
        int type, lflags;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
+       int resolve_flags = 0;
        int missing = 0;
        int attempts_remaining = 3;
 
        lock = xcalloc(1, sizeof(struct ref_lock));
        lock->lock_fd = -1;
 
-       refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
+       if (mustexist)
+               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;
+       }
+
+       refname = resolve_ref_unsafe(refname, resolve_flags,
+                                    lock->old_sha1, &type);
        if (!refname && errno == EISDIR) {
                /* we are trying to lock foo but we used to
                 * have foo/bar which now does not exist;
@@ -2166,7 +2264,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                        error("there are still refs under '%s'", orig_refname);
                        goto error_return;
                }
-               refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
+               refname = resolve_ref_unsafe(orig_refname, resolve_flags,
+                                            lock->old_sha1, &type);
        }
        if (type_p)
            *type_p = type;
@@ -2183,7 +2282,7 @@ 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(&ref_cache))) {
+            !is_refname_available(refname, skip, get_packed_refs(&ref_cache))) {
                last_errno = ENOTDIR;
                goto error_return;
        }
@@ -2241,9 +2340,7 @@ struct ref_lock *lock_any_ref_for_update(const char *refname,
                                         const unsigned char *old_sha1,
                                         int flags, int *type_p)
 {
-       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
-               return NULL;
-       return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
+       return lock_ref_sha1_basic(refname, old_sha1, NULL, flags, type_p);
 }
 
 /*
@@ -2445,8 +2542,8 @@ static void prune_ref(struct ref_to_prune *r)
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_delete(transaction, r->name, r->sha1,
-                                  REF_ISPRUNING, 1, &err) ||
-           ref_transaction_commit(transaction, NULL, &err)) {
+                                  REF_ISPRUNING, 1, NULL, &err) ||
+           ref_transaction_commit(transaction, &err)) {
                ref_transaction_free(transaction);
                error("%s", err.buf);
                strbuf_release(&err);
@@ -2510,7 +2607,7 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
                unsigned char sha1[20];
                int flags;
 
-               if (read_ref_full(entry->name, sha1, 0, &flags))
+               if (read_ref_full(entry->name, 0, sha1, &flags))
                        /* We should at least have found the packed ref. */
                        die("Internal error");
                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
@@ -2549,6 +2646,8 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
        struct string_list_item *ref_to_delete;
        int i, ret, removed = 0;
 
+       assert(err);
+
        /* Look for a packed ref */
        for (i = 0; i < n; i++)
                if (get_packed_ref(refnames[i]))
@@ -2559,13 +2658,8 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
                return 0; /* no refname exists in packed refs */
 
        if (lock_packed_refs(0)) {
-               if (err) {
-                       unable_to_lock_message(git_path("packed-refs"), errno,
-                                              err);
-                       return -1;
-               }
-               unable_to_lock_error(git_path("packed-refs"), errno);
-               return error("cannot delete '%s' from packed refs", refnames[i]);
+               unable_to_lock_message(git_path("packed-refs"), errno, err);
+               return -1;
        }
        packed = get_packed_refs(&ref_cache);
 
@@ -2591,23 +2685,25 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 
        /* Write what remains */
        ret = commit_packed_refs();
-       if (ret && err)
+       if (ret)
                strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
                            strerror(errno));
        return ret;
 }
 
-static int delete_ref_loose(struct ref_lock *lock, int flag)
+static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
 {
+       assert(err);
+
        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
                /*
                 * loose.  The loose file name is the same as the
                 * lockfile name, minus ".lock":
                 */
                char *loose_filename = get_locked_file_path(lock->lk);
-               int err = unlink_or_warn(loose_filename);
+               int res = unlink_or_msg(loose_filename, err);
                free(loose_filename);
-               if (err && errno != ENOENT)
+               if (res)
                        return 1;
        }
        return 0;
@@ -2621,8 +2717,8 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_delete(transaction, refname, sha1, delopt,
-                                  sha1 && !is_null_sha1(sha1), &err) ||
-           ref_transaction_commit(transaction, NULL, &err)) {
+                                  sha1 && !is_null_sha1(sha1), NULL, &err) ||
+           ref_transaction_commit(transaction, &err)) {
                error("%s", err.buf);
                ref_transaction_free(transaction);
                strbuf_release(&err);
@@ -2687,6 +2783,21 @@ static int rename_tmp_log(const char *newrefname)
        return 0;
 }
 
+static int rename_ref_available(const char *oldname, const char *newname)
+{
+       struct string_list skip = STRING_LIST_INIT_NODUP;
+       int ret;
+
+       string_list_insert(&skip, oldname);
+       ret = is_refname_available(newname, &skip, get_packed_refs(&ref_cache))
+           && is_refname_available(newname, &skip, get_loose_refs(&ref_cache));
+       string_list_clear(&skip, 0);
+       return ret;
+}
+
+static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
+                         const char *logmsg);
+
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
        unsigned char sha1[20], orig_sha1[20];
@@ -2699,17 +2810,15 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        if (log && S_ISLNK(loginfo.st_mode))
                return error("reflog for %s is a symlink", oldrefname);
 
-       symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
+       symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
+                                   orig_sha1, &flag);
        if (flag & REF_ISSYMREF)
                return error("refname %s is a symbolic ref, renaming it is not supported",
                        oldrefname);
        if (!symref)
                return error("refname %s not found", oldrefname);
 
-       if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
-               return 1;
-
-       if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
+       if (!rename_ref_available(oldrefname, newrefname))
                return 1;
 
        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
@@ -2721,7 +2830,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
                goto rollback;
        }
 
-       if (!read_ref_full(newrefname, sha1, 1, &flag) &&
+       if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
            delete_ref(newrefname, sha1, REF_NODEREF)) {
                if (errno==EISDIR) {
                        if (remove_empty_directories(git_path("%s", newrefname))) {
@@ -2739,7 +2848,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 
        logmoved = log;
 
-       lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
+       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, 0, NULL);
        if (!lock) {
                error("unable to lock %s for update", newrefname);
                goto rollback;
@@ -2754,7 +2863,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        return 0;
 
  rollback:
-       lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
+       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, 0, NULL);
        if (!lock) {
                error("unable to lock %s for rollback", oldrefname);
                goto rollbacklog;
@@ -2853,10 +2962,10 @@ int log_ref_setup(const char *refname, char *logfile, int bufsize)
 
        logfd = open(logfile, oflags, 0666);
        if (logfd < 0) {
-               if (!(oflags & O_CREAT) && errno == ENOENT)
+               if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
                        return 0;
 
-               if ((oflags & O_CREAT) && errno == EISDIR) {
+               if (errno == EISDIR) {
                        if (remove_empty_directories(logfile)) {
                                int save_errno = errno;
                                error("There are still logs under '%s'",
@@ -2934,8 +3043,11 @@ int is_branch(const char *refname)
        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 }
 
-/* This function must return a meaningful errno */
-int write_ref_sha1(struct ref_lock *lock,
+/*
+ * Write sha1 into the ref specified by the lock. Make sure that errno
+ * is sane on error.
+ */
+static int write_ref_sha1(struct ref_lock *lock,
        const unsigned char *sha1, const char *logmsg)
 {
        static char term = '\n';
@@ -2996,7 +3108,8 @@ int write_ref_sha1(struct ref_lock *lock,
                unsigned char head_sha1[20];
                int head_flag;
                const char *head_ref;
-               head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
+               head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
+                                             head_sha1, &head_flag);
                if (head_ref && (head_flag & REF_ISSYMREF) &&
                    !strcmp(head_ref, lock->ref_name))
                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
@@ -3367,7 +3480,7 @@ static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data
                                retval = do_for_each_reflog(name, fn, cb_data);
                        } else {
                                unsigned char sha1[20];
-                               if (read_ref_full(name->buf, sha1, 0, NULL))
+                               if (read_ref_full(name->buf, 0, sha1, NULL))
                                        retval = error("bad ref for %s", name->buf);
                                else
                                        retval = fn(name->buf, sha1, 0, cb_data);
@@ -3404,6 +3517,7 @@ struct ref_update {
        int have_old; /* 1 if old_sha1 is valid, 0 otherwise */
        struct ref_lock *lock;
        int type;
+       char *msg;
        const char refname[FLEX_ARRAY];
 };
 
@@ -3436,6 +3550,8 @@ struct ref_transaction {
 
 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 {
+       assert(err);
+
        return xcalloc(1, sizeof(struct ref_transaction));
 }
 
@@ -3446,9 +3562,10 @@ void ref_transaction_free(struct ref_transaction *transaction)
        if (!transaction)
                return;
 
-       for (i = 0; i < transaction->nr; i++)
+       for (i = 0; i < transaction->nr; i++) {
+               free(transaction->updates[i]->msg);
                free(transaction->updates[i]);
-
+       }
        free(transaction->updates);
        free(transaction);
 }
@@ -3469,57 +3586,80 @@ int ref_transaction_update(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *new_sha1,
                           const unsigned char *old_sha1,
-                          int flags, int have_old,
+                          int flags, int have_old, const char *msg,
                           struct strbuf *err)
 {
        struct ref_update *update;
 
+       assert(err);
+
        if (transaction->state != REF_TRANSACTION_OPEN)
                die("BUG: update called for transaction that is not open");
 
        if (have_old && !old_sha1)
                die("BUG: have_old is true but old_sha1 is NULL");
 
+       if (!is_null_sha1(new_sha1) &&
+           check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+               strbuf_addf(err, "refusing to update ref with bad name %s",
+                           refname);
+               return -1;
+       }
+
        update = add_update(transaction, refname);
        hashcpy(update->new_sha1, new_sha1);
        update->flags = flags;
        update->have_old = have_old;
        if (have_old)
                hashcpy(update->old_sha1, old_sha1);
+       if (msg)
+               update->msg = xstrdup(msg);
        return 0;
 }
 
 int ref_transaction_create(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *new_sha1,
-                          int flags,
+                          int flags, const char *msg,
                           struct strbuf *err)
 {
        struct ref_update *update;
 
+       assert(err);
+
        if (transaction->state != REF_TRANSACTION_OPEN)
                die("BUG: create called for transaction that is not open");
 
        if (!new_sha1 || is_null_sha1(new_sha1))
                die("BUG: create ref with null new_sha1");
 
+       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+               strbuf_addf(err, "refusing to create ref with bad name %s",
+                           refname);
+               return -1;
+       }
+
        update = add_update(transaction, refname);
 
        hashcpy(update->new_sha1, new_sha1);
        hashclr(update->old_sha1);
        update->flags = flags;
        update->have_old = 1;
+       if (msg)
+               update->msg = xstrdup(msg);
        return 0;
 }
 
 int ref_transaction_delete(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *old_sha1,
-                          int flags, int have_old,
+                          int flags, int have_old, const char *msg,
                           struct strbuf *err)
 {
        struct ref_update *update;
 
+       assert(err);
+
        if (transaction->state != REF_TRANSACTION_OPEN)
                die("BUG: delete called for transaction that is not open");
 
@@ -3533,6 +3673,8 @@ int ref_transaction_delete(struct ref_transaction *transaction,
                assert(!is_null_sha1(old_sha1));
                hashcpy(update->old_sha1, old_sha1);
        }
+       if (msg)
+               update->msg = xstrdup(msg);
        return 0;
 }
 
@@ -3546,8 +3688,8 @@ int update_ref(const char *action, const char *refname,
        t = ref_transaction_begin(&err);
        if (!t ||
            ref_transaction_update(t, refname, sha1, oldval, flags,
-                                  !!oldval, &err) ||
-           ref_transaction_commit(t, action, &err)) {
+                                  !!oldval, action, &err) ||
+           ref_transaction_commit(t, &err)) {
                const char *str = "update_ref failed for ref '%s': %s";
 
                ref_transaction_free(t);
@@ -3580,26 +3722,29 @@ static int ref_update_reject_duplicates(struct ref_update **updates, int n,
                                        struct strbuf *err)
 {
        int i;
+
+       assert(err);
+
        for (i = 1; i < n; i++)
                if (!strcmp(updates[i - 1]->refname, updates[i]->refname)) {
-                       const char *str =
-                               "Multiple updates for ref '%s' not allowed.";
-                       if (err)
-                               strbuf_addf(err, str, updates[i]->refname);
-
+                       strbuf_addf(err,
+                                   "Multiple updates for ref '%s' not allowed.",
+                                   updates[i]->refname);
                        return 1;
                }
        return 0;
 }
 
 int ref_transaction_commit(struct ref_transaction *transaction,
-                          const char *msg, struct strbuf *err)
+                          struct strbuf *err)
 {
        int ret = 0, delnum = 0, i;
        const char **delnames;
        int n = transaction->nr;
        struct ref_update **updates = transaction->updates;
 
+       assert(err);
+
        if (transaction->state != REF_TRANSACTION_OPEN)
                die("BUG: commit called for transaction that is not open");
 
@@ -3613,25 +3758,31 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 
        /* Copy, sort, and reject duplicate refs */
        qsort(updates, n, sizeof(*updates), ref_update_compare);
-       ret = ref_update_reject_duplicates(updates, n, err);
-       if (ret)
+       if (ref_update_reject_duplicates(updates, n, err)) {
+               ret = TRANSACTION_GENERIC_ERROR;
                goto cleanup;
+       }
 
        /* Acquire all locks while verifying old values */
        for (i = 0; i < n; i++) {
                struct ref_update *update = updates[i];
-
-               update->lock = lock_any_ref_for_update(update->refname,
-                                                      (update->have_old ?
-                                                       update->old_sha1 :
-                                                       NULL),
-                                                      update->flags,
-                                                      &update->type);
+               int flags = update->flags;
+
+               if (is_null_sha1(update->new_sha1))
+                       flags |= REF_DELETING;
+               update->lock = lock_ref_sha1_basic(update->refname,
+                                                  (update->have_old ?
+                                                   update->old_sha1 :
+                                                   NULL),
+                                                  NULL,
+                                                  flags,
+                                                  &update->type);
                if (!update->lock) {
-                       if (err)
-                               strbuf_addf(err, "Cannot lock the ref '%s'.",
-                                           update->refname);
-                       ret = 1;
+                       ret = (errno == ENOTDIR)
+                               ? TRANSACTION_NAME_CONFLICT
+                               : TRANSACTION_GENERIC_ERROR;
+                       strbuf_addf(err, "Cannot lock the ref '%s'.",
+                                   update->refname);
                        goto cleanup;
                }
        }
@@ -3641,15 +3792,15 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                struct ref_update *update = updates[i];
 
                if (!is_null_sha1(update->new_sha1)) {
-                       ret = write_ref_sha1(update->lock, update->new_sha1,
-                                            msg);
-                       update->lock = NULL; /* freed by write_ref_sha1 */
-                       if (ret) {
-                               if (err)
-                                       strbuf_addf(err, "Cannot update the ref '%s'.",
-                                                   update->refname);
+                       if (write_ref_sha1(update->lock, update->new_sha1,
+                                          update->msg)) {
+                               update->lock = NULL; /* freed by write_ref_sha1 */
+                               strbuf_addf(err, "Cannot update the ref '%s'.",
+                                           update->refname);
+                               ret = TRANSACTION_GENERIC_ERROR;
                                goto cleanup;
                        }
+                       update->lock = NULL; /* freed by write_ref_sha1 */
                }
        }
 
@@ -3658,13 +3809,20 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                struct ref_update *update = updates[i];
 
                if (update->lock) {
-                       ret |= delete_ref_loose(update->lock, update->type);
+                       if (delete_ref_loose(update->lock, update->type, err)) {
+                               ret = TRANSACTION_GENERIC_ERROR;
+                               goto cleanup;
+                       }
+
                        if (!(update->flags & REF_ISPRUNING))
                                delnames[delnum++] = update->lock->ref_name;
                }
        }
 
-       ret |= repack_without_refs(delnames, delnum, err);
+       if (repack_without_refs(delnames, delnum, err)) {
+               ret = TRANSACTION_GENERIC_ERROR;
+               goto cleanup;
+       }
        for (i = 0; i < delnum; i++)
                unlink_or_warn(git_path("logs/%s", delnames[i]));
        clear_loose_ref_cache(&ref_cache);