1 files changed, 483 insertions, 117 deletions

diff --git a/refs.c b/refs.c
index be095cb07d..e3c05110e5 100644
--- a/refs.c
+++ b/refs.c
@@ -6,6 +6,7 @@
 
 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
 #define REF_KNOWS_PEELED 04
+#define REF_BROKEN 010
 
 struct ref_list {
 	struct ref_list *next;
@@ -156,7 +157,7 @@ static struct cached_refs {
 	char did_packed;
 	struct ref_list *loose;
 	struct ref_list *packed;
-} cached_refs;
+} cached_refs, submodule_refs;
 static struct ref_list *current_ref;
 
 static struct ref_list *extra_refs;
@@ -228,23 +229,45 @@ void clear_extra_refs(void)
 	extra_refs = NULL;
 }
 
-static struct ref_list *get_packed_refs(void)
+static struct ref_list *get_packed_refs(const char *submodule)
 {
-	if (!cached_refs.did_packed) {
-		FILE *f = fopen(git_path("packed-refs"), "r");
-		cached_refs.packed = NULL;
+	const char *packed_refs_file;
+	struct cached_refs *refs;
+
+	if (submodule) {
+		packed_refs_file = git_path_submodule(submodule, "packed-refs");
+		refs = &submodule_refs;
+		free_ref_list(refs->packed);
+	} else {
+		packed_refs_file = git_path("packed-refs");
+		refs = &cached_refs;
+	}
+
+	if (!refs->did_packed || submodule) {
+		FILE *f = fopen(packed_refs_file, "r");
+		refs->packed = NULL;
 		if (f) {
-			read_packed_refs(f, &cached_refs);
+			read_packed_refs(f, refs);
 			fclose(f);
 		}
-		cached_refs.did_packed = 1;
+		refs->did_packed = 1;
 	}
-	return cached_refs.packed;
+	return refs->packed;
 }
 
-static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
+static struct ref_list *get_ref_dir(const char *submodule, const char *base,
+				    struct ref_list *list)
 {
-	DIR *dir = opendir(git_path("%s", base));
+	DIR *dir;
+	const char *path;
+
+	if (submodule)
+		path = git_path_submodule(submodule, "%s", base);
+	else
+		path = git_path("%s", base);
+
+
+	dir = opendir(path);
 
 	if (dir) {
 		struct dirent *de;
@@ -260,6 +283,7 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 			struct stat st;
 			int flag;
 			int namelen;
+			const char *refdir;
 
 			if (de->d_name[0] == '.')
 				continue;
@@ -269,16 +293,27 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 			if (has_extension(de->d_name, ".lock"))
 				continue;
 			memcpy(ref + baselen, de->d_name, namelen+1);
-			if (stat(git_path("%s", ref), &st) < 0)
+			refdir = submodule
+				? git_path_submodule(submodule, "%s", ref)
+				: git_path("%s", ref);
+			if (stat(refdir, &st) < 0)
 				continue;
 			if (S_ISDIR(st.st_mode)) {
-				list = get_ref_dir(ref, list);
-				continue;
-			}
-			if (!resolve_ref(ref, sha1, 1, &flag)) {
-				error("%s points nowhere!", ref);
+				list = get_ref_dir(submodule, ref, list);
 				continue;
 			}
+			if (submodule) {
+				hashclr(sha1);
+				flag = 0;
+				if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
+					hashclr(sha1);
+					flag |= REF_BROKEN;
+				}
+			} else
+				if (!resolve_ref(ref, sha1, 1, &flag)) {
+					hashclr(sha1);
+					flag |= REF_BROKEN;
+				}
 			list = add_ref(ref, sha1, flag, list, NULL);
 		}
 		free(ref);
@@ -287,10 +322,50 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 	return sort_ref_list(list);
 }
 
-static struct ref_list *get_loose_refs(void)
+struct warn_if_dangling_data {
+	FILE *fp;
+	const char *refname;
+	const char *msg_fmt;
+};
+
+static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
+				   int flags, void *cb_data)
+{
+	struct warn_if_dangling_data *d = cb_data;
+	const char *resolves_to;
+	unsigned char junk[20];
+
+	if (!(flags & REF_ISSYMREF))
+		return 0;
+
+	resolves_to = resolve_ref(refname, junk, 0, NULL);
+	if (!resolves_to || strcmp(resolves_to, d->refname))
+		return 0;
+
+	fprintf(d->fp, d->msg_fmt, refname);
+	return 0;
+}
+
+void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
+{
+	struct warn_if_dangling_data data;
+
+	data.fp = fp;
+	data.refname = refname;
+	data.msg_fmt = msg_fmt;
+	for_each_rawref(warn_if_dangling_symref, &data);
+}
+
+static struct ref_list *get_loose_refs(const char *submodule)
 {
+	if (submodule) {
+		free_ref_list(submodule_refs.loose);
+		submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
+		return submodule_refs.loose;
+	}
+
 	if (!cached_refs.did_loose) {
-		cached_refs.loose = get_ref_dir("refs", NULL);
+		cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
 		cached_refs.did_loose = 1;
 	}
 	return cached_refs.loose;
@@ -390,6 +465,18 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *re
 	return retval;
 }
 
+/*
+ * If the "reading" argument is set, this function finds out what _object_
+ * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
+ * has to exist, and if it is symbolic, it has to point at an existing ref,
+ * because the "read" goes through the symref to the ref it points at.
+ *
+ * The access that is not "reading" may often be "writing", but does not
+ * have to; it can be merely checking _where it leads to_. If it is a
+ * prelude to "writing" to the ref, a write to a symref that points at
+ * yet-to-be-born ref will create the real ref pointed by the symref.
+ * reading=0 allows the caller to check where such a symref leads to.
+ */
 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 {
 	int depth = MAXDEPTH;
@@ -410,15 +497,9 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
 			return NULL;
 
 		git_snpath(path, sizeof(path), "%s", ref);
-		/* Special case: non-existing file.
-		 * Not having the refs/heads/new-branch is OK
-		 * if we are writing into it, so is .git/HEAD
-		 * that points at refs/heads/master still to be
-		 * born.  It is NOT OK if we are resolving for
-		 * reading.
-		 */
+		/* Special case: non-existing file. */
 		if (lstat(path, &st) < 0) {
-			struct ref_list *list = get_packed_refs();
+			struct ref_list *list = get_packed_refs(NULL);
 			while (list) {
 				if (!strcmp(ref, list->name)) {
 					hashcpy(sha1, list->sha1);
@@ -485,6 +566,13 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
 	return ref;
 }
 
+/* The argument to filter_refs */
+struct ref_filter {
+	const char *pattern;
+	each_ref_fn *fn;
+	void *cb_data;
+};
+
 int read_ref(const char *ref, unsigned char *sha1)
 {
 	if (resolve_ref(ref, sha1, 1, NULL))
@@ -492,21 +580,34 @@ int read_ref(const char *ref, unsigned char *sha1)
 	return -1;
 }
 
+#define DO_FOR_EACH_INCLUDE_BROKEN 01
 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
-		      void *cb_data, struct ref_list *entry)
+		      int flags, void *cb_data, struct ref_list *entry)
 {
 	if (strncmp(base, entry->name, trim))
 		return 0;
-	if (is_null_sha1(entry->sha1))
-		return 0;
-	if (!has_sha1_file(entry->sha1)) {
-		error("%s does not point to a valid object!", entry->name);
-		return 0;
+
+	if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
+		if (entry->flag & REF_BROKEN)
+			return 0; /* ignore dangling symref */
+		if (!has_sha1_file(entry->sha1)) {
+			error("%s does not point to a valid object!", entry->name);
+			return 0;
+		}
 	}
 	current_ref = entry;
 	return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 }
 
+static int filter_refs(const char *ref, const unsigned char *sha, int flags,
+	void *data)
+{
+	struct ref_filter *filter = (struct ref_filter *)data;
+	if (fnmatch(filter->pattern, ref, 0))
+		return 0;
+	return filter->fn(ref, sha, flags, filter->cb_data);
+}
+
 int peel_ref(const char *ref, unsigned char *sha1)
 {
 	int flag;
@@ -527,7 +628,7 @@ int peel_ref(const char *ref, unsigned char *sha1)
 		return -1;
 
 	if ((flag & REF_ISPACKED)) {
-		struct ref_list *list = get_packed_refs();
+		struct ref_list *list = get_packed_refs(NULL);
 
 		while (list) {
 			if (!strcmp(list->name, ref)) {
@@ -554,17 +655,17 @@ fallback:
 	return -1;
 }
 
-static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
-			   void *cb_data)
+static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
+			   int trim, int flags, void *cb_data)
 {
 	int retval = 0;
-	struct ref_list *packed = get_packed_refs();
-	struct ref_list *loose = get_loose_refs();
+	struct ref_list *packed = get_packed_refs(submodule);
+	struct ref_list *loose = get_loose_refs(submodule);
 
 	struct ref_list *extra;
 
 	for (extra = extra_refs; extra; extra = extra->next)
-		retval = do_one_ref(base, fn, trim, cb_data, extra);
+		retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 
 	while (packed && loose) {
 		struct ref_list *entry;
@@ -580,13 +681,13 @@ static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 			entry = packed;
 			packed = packed->next;
 		}
-		retval = do_one_ref(base, fn, trim, cb_data, entry);
+		retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 		if (retval)
 			goto end_each;
 	}
 
 	for (packed = packed ? packed : loose; packed; packed = packed->next) {
-		retval = do_one_ref(base, fn, trim, cb_data, packed);
+		retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 		if (retval)
 			goto end_each;
 	}
@@ -596,34 +697,130 @@ end_each:
 	return retval;
 }
 
-int head_ref(each_ref_fn fn, void *cb_data)
+
+static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 {
 	unsigned char sha1[20];
 	int flag;
 
+	if (submodule) {
+		if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
+			return fn("HEAD", sha1, 0, cb_data);
+
+		return 0;
+	}
+
 	if (resolve_ref("HEAD", sha1, 1, &flag))
 		return fn("HEAD", sha1, flag, cb_data);
+
 	return 0;
 }
 
+int head_ref(each_ref_fn fn, void *cb_data)
+{
+	return do_head_ref(NULL, fn, cb_data);
+}
+
+int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return do_head_ref(submodule, fn, cb_data);
+}
+
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref("refs/", fn, 0, cb_data);
+	return do_for_each_ref(NULL, "refs/", 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, "refs/", 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);
+}
+
+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);
 }
 
 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref("refs/tags/", fn, 10, cb_data);
+	return for_each_ref_in("refs/tags/", fn, cb_data);
+}
+
+int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 }
 
 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref("refs/heads/", fn, 11, cb_data);
+	return for_each_ref_in("refs/heads/", fn, cb_data);
+}
+
+int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 }
 
 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
+	return for_each_ref_in("refs/remotes/", fn, cb_data);
+}
+
+int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
+}
+
+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);
+}
+
+int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
+	const char *prefix, void *cb_data)
+{
+	struct strbuf real_pattern = STRBUF_INIT;
+	struct ref_filter filter;
+	int ret;
+
+	if (!prefix && prefixcmp(pattern, "refs/"))
+		strbuf_addstr(&real_pattern, "refs/");
+	else if (prefix)
+		strbuf_addstr(&real_pattern, prefix);
+	strbuf_addstr(&real_pattern, pattern);
+
+	if (!has_glob_specials(pattern)) {
+		/* Append implied '/' '*' if not present. */
+		if (real_pattern.buf[real_pattern.len - 1] != '/')
+			strbuf_addch(&real_pattern, '/');
+		/* No need to check for '*', there is none. */
+		strbuf_addch(&real_pattern, '*');
+	}
+
+	filter.pattern = real_pattern.buf;
+	filter.fn = fn;
+	filter.cb_data = cb_data;
+	ret = for_each_ref(filter_refs, &filter);
+
+	strbuf_release(&real_pattern);
+	return ret;
+}
+
+int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
+{
+	return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
+}
+
+int for_each_rawref(each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(NULL, "refs/", fn, 0,
+			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 
 /*
@@ -634,12 +831,14 @@ int for_each_remote_ref(each_ref_fn fn, void *cb_data)
  * - it has double dots "..", or
  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  * - it ends with a "/".
+ * - it ends with ".lock"
+ * - it contains a "\" (backslash)
  */
 
 static inline int bad_ref_char(int ch)
 {
 	if (((unsigned) ch) <= ' ' ||
-	    ch == '~' || ch == '^' || ch == ':')
+	    ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 		return 1;
 	/* 2.13 Pattern Matching Notation */
 	if (ch == '?' || ch == '[') /* Unsupported */
@@ -651,7 +850,8 @@ static inline int bad_ref_char(int ch)
 
 int check_ref_format(const char *ref)
 {
-	int ch, level, bad_type;
+	int ch, level, bad_type, last;
+	int ret = CHECK_REF_FORMAT_OK;
 	const char *cp = ref;
 
 	level = 0;
@@ -667,33 +867,49 @@ int check_ref_format(const char *ref)
 			return CHECK_REF_FORMAT_ERROR;
 		bad_type = bad_ref_char(ch);
 		if (bad_type) {
-			return (bad_type == 2 && !*cp)
-				? CHECK_REF_FORMAT_WILDCARD
-				: CHECK_REF_FORMAT_ERROR;
+			if (bad_type == 2 && (!*cp || *cp == '/') &&
+			    ret == CHECK_REF_FORMAT_OK)
+				ret = CHECK_REF_FORMAT_WILDCARD;
+			else
+				return CHECK_REF_FORMAT_ERROR;
 		}
 
+		last = ch;
 		/* scan the rest of the path component */
 		while ((ch = *cp++) != 0) {
 			bad_type = bad_ref_char(ch);
-			if (bad_type) {
-				return (bad_type == 2 && !*cp)
-					? CHECK_REF_FORMAT_WILDCARD
-					: CHECK_REF_FORMAT_ERROR;
-			}
+			if (bad_type)
+				return CHECK_REF_FORMAT_ERROR;
 			if (ch == '/')
 				break;
-			if (ch == '.' && *cp == '.')
+			if (last == '.' && ch == '.')
 				return CHECK_REF_FORMAT_ERROR;
+			if (last == '@' && ch == '{')
+				return CHECK_REF_FORMAT_ERROR;
+			last = ch;
 		}
 		level++;
 		if (!ch) {
+			if (ref <= cp - 2 && cp[-2] == '.')
+				return CHECK_REF_FORMAT_ERROR;
 			if (level < 2)
 				return CHECK_REF_FORMAT_ONELEVEL;
-			return CHECK_REF_FORMAT_OK;
+			if (has_extension(ref, ".lock"))
+				return CHECK_REF_FORMAT_ERROR;
+			return ret;
 		}
 	}
 }
 
+const char *prettify_refname(const char *name)
+{
+	return name + (
+		!prefixcmp(name, "refs/heads/") ? 11 :
+		!prefixcmp(name, "refs/tags/") ? 10 :
+		!prefixcmp(name, "refs/remotes/") ? 13 :
+		0);
+}
+
 const char *ref_rev_parse_rules[] = {
 	"%.*s",
 	"refs/%.*s",
@@ -754,7 +970,7 @@ static int remove_empty_directories(const char *file)
 	strbuf_init(&path, 20);
 	strbuf_addstr(&path, file);
 
-	result = remove_dir_recursively(&path, 1);
+	result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 
 	strbuf_release(&path);
 
@@ -827,8 +1043,10 @@ static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char
 	 * name is a proper prefix of our refname.
 	 */
 	if (missing &&
-            !is_refname_available(ref, NULL, get_packed_refs(), 0))
+	     !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
+		last_errno = ENOTDIR;
 		goto error_return;
+	}
 
 	lock->lk = xcalloc(1, sizeof(struct lock_file));
 
@@ -888,7 +1106,7 @@ static int repack_without_ref(const char *refname)
 	int fd;
 	int found = 0;
 
-	packed_ref_list = get_packed_refs();
+	packed_ref_list = get_packed_refs(NULL);
 	for (list = packed_ref_list; list; list = list->next) {
 		if (!strcmp(refname, list->name)) {
 			found = 1;
@@ -898,8 +1116,10 @@ static int repack_without_ref(const char *refname)
 	if (!found)
 		return 0;
 	fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
-	if (fd < 0)
+	if (fd < 0) {
+		unable_to_lock_error(git_path("packed-refs"), errno);
 		return error("cannot delete '%s' from packed refs", refname);
+	}
 
 	for (list = packed_ref_list; list; list = list->next) {
 		char line[PATH_MAX + 100];
@@ -936,12 +1156,10 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 		} else {
 			path = git_path("%s", refname);
 		}
-		err = unlink(path);
-		if (err && errno != ENOENT) {
+		err = unlink_or_warn(path);
+		if (err && errno != ENOENT)
 			ret = 1;
-			error("unlink(%s) failed: %s",
-			      path, strerror(errno));
-		}
+
 		if (!(delopt & REF_NODEREF))
 			lock->lk->filename[i] = '.';
 	}
@@ -951,15 +1169,21 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 	 */
 	ret |= repack_without_ref(refname);
 
-	err = unlink(git_path("logs/%s", lock->ref_name));
-	if (err && errno != ENOENT)
-		fprintf(stderr, "warning: unlink(%s) failed: %s",
-			git_path("logs/%s", lock->ref_name), strerror(errno));
+	unlink_or_warn(git_path("logs/%s", lock->ref_name));
 	invalidate_cached_refs();
 	unlock_ref(lock);
 	return ret;
 }
 
+/*
+ * People using contrib's git-new-workdir have .git/logs/refs ->
+ * /some/other/path/.git/logs/refs, and that may live on another device.
+ *
+ * IOW, to avoid cross device rename errors, the temporary renamed log must
+ * live into logs/refs.
+ */
+#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
+
 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 {
 	static const char renamed_ref[] = "RENAMED-REF";
@@ -980,10 +1204,10 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 	if (!symref)
 		return error("refname %s not found", oldref);
 
-	if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
+	if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
 		return 1;
 
-	if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
+	if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
 		return 1;
 
 	lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
@@ -993,8 +1217,8 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 	if (write_ref_sha1(lock, orig_sha1, logmsg))
 		return error("unable to save current sha1 in %s", renamed_ref);
 
-	if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
-		return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
+	if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
+		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
 			oldref, strerror(errno));
 
 	if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
@@ -1020,7 +1244,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 	}
 
  retry:
-	if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
+	if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
 		if (errno==EISDIR || errno==ENOTDIR) {
 			/*
 			 * rename(a, b) when b is an existing
@@ -1033,7 +1257,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 			}
 			goto retry;
 		} else {
-			error("unable to move logfile tmp-renamed-log to logs/%s: %s",
+			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
 				newref, strerror(errno));
 			goto rollback;
 		}
@@ -1073,8 +1297,8 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 		error("unable to restore logfile %s from %s: %s",
 			oldref, newref, strerror(errno));
 	if (!logmoved && log &&
-	    rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
-		error("unable to restore logfile %s from tmp-renamed-log: %s",
+	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
+		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
 			oldref, strerror(errno));
 
 	return 1;
@@ -1132,51 +1356,65 @@ static int copy_msg(char *buf, const char *msg)
 	return cp - buf;
 }
 
-static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
-			 const unsigned char *new_sha1, const char *msg)
+int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
 {
-	int logfd, written, oflags = O_APPEND | O_WRONLY;
-	unsigned maxlen, len;
-	int msglen;
-	char log_file[PATH_MAX];
-	char *logrec;
-	const char *committer;
-
-	if (log_all_ref_updates < 0)
-		log_all_ref_updates = !is_bare_repository();
-
-	git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
+	int logfd, oflags = O_APPEND | O_WRONLY;
 
+	git_snpath(logfile, bufsize, "logs/%s", ref_name);
 	if (log_all_ref_updates &&
 	    (!prefixcmp(ref_name, "refs/heads/") ||
 	     !prefixcmp(ref_name, "refs/remotes/") ||
+	     !prefixcmp(ref_name, "refs/notes/") ||
 	     !strcmp(ref_name, "HEAD"))) {
-		if (safe_create_leading_directories(log_file) < 0)
+		if (safe_create_leading_directories(logfile) < 0)
 			return error("unable to create directory for %s",
-				     log_file);
+				     logfile);
 		oflags |= O_CREAT;
 	}
 
-	logfd = open(log_file, oflags, 0666);
+	logfd = open(logfile, oflags, 0666);
 	if (logfd < 0) {
 		if (!(oflags & O_CREAT) && errno == ENOENT)
 			return 0;
 
 		if ((oflags & O_CREAT) && errno == EISDIR) {
-			if (remove_empty_directories(log_file)) {
+			if (remove_empty_directories(logfile)) {
 				return error("There are still logs under '%s'",
-					     log_file);
+					     logfile);
 			}
-			logfd = open(log_file, oflags, 0666);
+			logfd = open(logfile, oflags, 0666);
 		}
 
 		if (logfd < 0)
 			return error("Unable to append to %s: %s",
-				     log_file, strerror(errno));
+				     logfile, strerror(errno));
 	}
 
-	adjust_shared_perm(log_file);
+	adjust_shared_perm(logfile);
+	close(logfd);
+	return 0;
+}
 
+static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
+			 const unsigned char *new_sha1, const char *msg)
+{
+	int logfd, result, written, oflags = O_APPEND | O_WRONLY;
+	unsigned maxlen, len;
+	int msglen;
+	char log_file[PATH_MAX];
+	char *logrec;
+	const char *committer;
+
+	if (log_all_ref_updates < 0)
+		log_all_ref_updates = !is_bare_repository();
+
+	result = log_ref_setup(ref_name, log_file, sizeof(log_file));
+	if (result)
+		return result;
+
+	logfd = open(log_file, oflags);
+	if (logfd < 0)
+		return 0;
 	msglen = msg ? strlen(msg) : 0;
 	committer = git_committer_info(0);
 	maxlen = strlen(committer) + msglen + 100;
@@ -1315,7 +1553,7 @@ int create_symref(const char *ref_target, const char *refs_heads_master,
 	if (adjust_shared_perm(git_HEAD)) {
 		error("Unable to fix permissions on %s", lockpath);
 	error_unlink_return:
-		unlink(lockpath);
+		unlink_or_warn(lockpath);
 	error_free_return:
 		free(git_HEAD);
 		return -1;
@@ -1355,7 +1593,7 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 	logfile = git_path("logs/%s", ref);
 	logfd = open(logfile, O_RDONLY, 0);
 	if (logfd < 0)
-		die("Unable to read log %s: %s", logfile, strerror(errno));
+		die_errno("Unable to read log '%s'", logfile);
 	fstat(logfd, &st);
 	if (!st.st_size)
 		die("Log %s is empty.", logfile);
@@ -1395,8 +1633,7 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 				if (get_sha1_hex(rec + 41, sha1))
 					die("Log %s is corrupt.", logfile);
 				if (hashcmp(logged_sha1, sha1)) {
-					fprintf(stderr,
-						"warning: Log %s has gap after %s.\n",
+					warning("Log %s has gap after %s.",
 						logfile, show_date(date, tz, DATE_RFC2822));
 				}
 			}
@@ -1408,8 +1645,7 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 				if (get_sha1_hex(rec + 41, logged_sha1))
 					die("Log %s is corrupt.", logfile);
 				if (hashcmp(logged_sha1, sha1)) {
-					fprintf(stderr,
-						"warning: Log %s unexpectedly ended on %s.\n",
+					warning("Log %s unexpectedly ended on %s.",
 						logfile, show_date(date, tz, DATE_RFC2822));
 				}
 			}
@@ -1447,29 +1683,41 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 	return 1;
 }
 
-int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
+int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
 {
 	const char *logfile;
 	FILE *logfp;
-	char buf[1024];
+	struct strbuf sb = STRBUF_INIT;
 	int ret = 0;
 
 	logfile = git_path("logs/%s", ref);
 	logfp = fopen(logfile, "r");
 	if (!logfp)
 		return -1;
-	while (fgets(buf, sizeof(buf), logfp)) {
+
+	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;
+		}
+	}
+
+	while (!strbuf_getwholeline(&sb, logfp, '\n')) {
 		unsigned char osha1[20], nsha1[20];
 		char *email_end, *message;
 		unsigned long timestamp;
-		int len, tz;
+		int tz;
 
 		/* old SP new SP name <email> SP time TAB msg LF */
-		len = strlen(buf);
-		if (len < 83 || buf[len-1] != '\n' ||
-		    get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
-		    get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
-		    !(email_end = strchr(buf + 82, '>')) ||
+		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] != ' ' ||
@@ -1483,14 +1731,21 @@ int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
 			message += 6;
 		else
 			message += 7;
-		ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
+		ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
+			 cb_data);
 		if (ret)
 			break;
 	}
 	fclose(logfp);
+	strbuf_release(&sb);
 	return ret;
 }
 
+int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
+{
+	return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
+}
+
 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
 {
 	DIR *dir = opendir(git_path("logs/%s", base));
@@ -1571,10 +1826,121 @@ int update_ref(const char *action, const char *refname,
 	return 0;
 }
 
-struct ref *find_ref_by_name(struct ref *list, const char *name)
+struct ref *find_ref_by_name(const struct ref *list, const char *name)
 {
 	for ( ; list; list = list->next)
 		if (!strcmp(list->name, name))
-			return list;
+			return (struct ref *)list;
 	return NULL;
 }
+
+/*
+ * generate a format suitable for scanf from a ref_rev_parse_rules
+ * rule, that is replace the "%.*s" spec with a "%s" spec
+ */
+static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
+{
+	char *spec;
+
+	spec = strstr(rule, "%.*s");
+	if (!spec || strstr(spec + 4, "%.*s"))
+		die("invalid rule in ref_rev_parse_rules: %s", rule);
+
+	/* copy all until spec */
+	strncpy(scanf_fmt, rule, spec - rule);
+	scanf_fmt[spec - rule] = '\0';
+	/* copy new spec */
+	strcat(scanf_fmt, "%s");
+	/* copy remaining rule */
+	strcat(scanf_fmt, spec + 4);
+
+	return;
+}
+
+char *shorten_unambiguous_ref(const char *ref, int strict)
+{
+	int i;
+	static char **scanf_fmts;
+	static int nr_rules;
+	char *short_name;
+
+	/* pre generate scanf formats from ref_rev_parse_rules[] */
+	if (!nr_rules) {
+		size_t total_len = 0;
+
+		/* the rule list is NULL terminated, count them first */
+		for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
+			/* no +1 because strlen("%s") < strlen("%.*s") */
+			total_len += strlen(ref_rev_parse_rules[nr_rules]);
+
+		scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
+
+		total_len = 0;
+		for (i = 0; i < nr_rules; i++) {
+			scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
+					+ total_len;
+			gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
+			total_len += strlen(ref_rev_parse_rules[i]);
+		}
+	}
+
+	/* bail out if there are no rules */
+	if (!nr_rules)
+		return xstrdup(ref);
+
+	/* buffer for scanf result, at most ref must fit */
+	short_name = xstrdup(ref);
+
+	/* skip first rule, it will always match */
+	for (i = nr_rules - 1; i > 0 ; --i) {
+		int j;
+		int rules_to_fail = i;
+		int short_name_len;
+
+		if (1 != sscanf(ref, scanf_fmts[i], short_name))
+			continue;
+
+		short_name_len = strlen(short_name);
+
+		/*
+		 * in strict mode, all (except the matched one) rules
+		 * must fail to resolve to a valid non-ambiguous ref
+		 */
+		if (strict)
+			rules_to_fail = nr_rules;
+
+		/*
+		 * check if the short name resolves to a valid ref,
+		 * but use only rules prior to the matched one
+		 */
+		for (j = 0; j < rules_to_fail; j++) {
+			const char *rule = ref_rev_parse_rules[j];
+			unsigned char short_objectname[20];
+			char refname[PATH_MAX];
+
+			/* skip matched rule */
+			if (i == j)
+				continue;
+
+			/*
+			 * the short name is ambiguous, if it resolves
+			 * (with this previous rule) to a valid ref
+			 * read_ref() returns 0 on success
+			 */
+			mksnpath(refname, sizeof(refname),
+				 rule, short_name_len, short_name);
+			if (!read_ref(refname, short_objectname))
+				break;
+		}
+
+		/*
+		 * short name is non-ambiguous if all previous rules
+		 * haven't resolved to a valid ref
+		 */
+		if (j == rules_to_fail)
+			return short_name;
+	}
+
+	free(short_name);
+	return xstrdup(ref);
+}