Make ref resolution saner

The old code used to totally mix up the notion of a ref-name and the path
that that ref was associated with.  That was not only horribly ugly (a
number of users got the path, and then wanted to try to turn it back into
a ref-name again), but it fundamnetally doesn't work at all once we do any
setup where a ref doesn't have a 1:1 relationship with a particular
pathname.

This fixes things up so that we use the ref-name throughout, and only
turn it into a pathname once we actually look it up in the filesystem.
That makes a lot of things much clearer and more straightforward.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 37 insertions, 32 deletions

diff --git a/refs.c b/refs.c
index 72e22834fa..50c25d3d28 100644
--- a/refs.c
+++ b/refs.c
@@ -93,11 +93,11 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 	if (dir) {
 		struct dirent *de;
 		int baselen = strlen(base);
-		char *path = xmalloc(baselen + 257);
+		char *ref = xmalloc(baselen + 257);
 
-		memcpy(path, base, baselen);
+		memcpy(ref, base, baselen);
 		if (baselen && base[baselen-1] != '/')
-			path[baselen++] = '/';
+			ref[baselen++] = '/';
 
 		while ((de = readdir(dir)) != NULL) {
 			unsigned char sha1[20];
@@ -111,20 +111,20 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 				continue;
 			if (has_extension(de->d_name, ".lock"))
 				continue;
-			memcpy(path + baselen, de->d_name, namelen+1);
-			if (stat(git_path("%s", path), &st) < 0)
+			memcpy(ref + baselen, de->d_name, namelen+1);
+			if (stat(git_path("%s", ref), &st) < 0)
 				continue;
 			if (S_ISDIR(st.st_mode)) {
-				list = get_ref_dir(path, list);
+				list = get_ref_dir(ref, list);
 				continue;
 			}
-			if (read_ref(git_path("%s", path), sha1) < 0) {
-				error("%s points nowhere!", path);
+			if (read_ref(ref, sha1) < 0) {
+				error("%s points nowhere!", ref);
 				continue;
 			}
-			list = add_ref(path, sha1, list);
+			list = add_ref(ref, sha1, list);
 		}
-		free(path);
+		free(ref);
 		closedir(dir);
 	}
 	return list;
@@ -145,12 +145,14 @@ static struct ref_list *get_loose_refs(void)
 /* We allow "recursive" symbolic refs. Only within reason, though */
 #define MAXDEPTH 5
 
-const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
+const char *resolve_ref(const char *ref, unsigned char *sha1, int reading)
 {
 	int depth = MAXDEPTH, len;
 	char buffer[256];
+	static char ref_buffer[256];
 
 	for (;;) {
+		const char *path = git_path("%s", ref);
 		struct stat st;
 		char *buf;
 		int fd;
@@ -169,14 +171,16 @@ const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
 			if (reading || errno != ENOENT)
 				return NULL;
 			hashclr(sha1);
-			return path;
+			return ref;
 		}
 
 		/* Follow "normalized" - ie "refs/.." symlinks by hand */
 		if (S_ISLNK(st.st_mode)) {
 			len = readlink(path, buffer, sizeof(buffer)-1);
 			if (len >= 5 && !memcmp("refs/", buffer, 5)) {
-				path = git_path("%.*s", len, buffer);
+				buffer[len] = 0;
+				strcpy(ref_buffer, buffer);
+				ref = ref_buffer;
 				continue;
 			}
 		}
@@ -201,19 +205,22 @@ const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
 		while (len && isspace(*buf))
 			buf++, len--;
 		while (len && isspace(buf[len-1]))
-			buf[--len] = 0;
-		path = git_path("%.*s", len, buf);
+			len--;
+		buf[len] = 0;
+		memcpy(ref_buffer, buf, len + 1);
+		ref = ref_buffer;
 	}
 	if (len < 40 || get_sha1_hex(buffer, sha1))
 		return NULL;
-	return path;
+	return ref;
 }
 
-int create_symref(const char *git_HEAD, const char *refs_heads_master)
+int create_symref(const char *ref_target, const char *refs_heads_master)
 {
 	const char *lockpath;
 	char ref[1000];
 	int fd, len, written;
+	const char *git_HEAD = git_path("%s", ref_target);
 
 #ifndef NO_SYMLINK_HEAD
 	if (prefer_symlink_refs) {
@@ -251,9 +258,9 @@ int create_symref(const char *git_HEAD, const char *refs_heads_master)
 	return 0;
 }
 
-int read_ref(const char *filename, unsigned char *sha1)
+int read_ref(const char *ref, unsigned char *sha1)
 {
-	if (resolve_ref(filename, sha1, 1))
+	if (resolve_ref(ref, sha1, 1))
 		return 0;
 	return -1;
 }
@@ -306,7 +313,7 @@ static int do_for_each_ref(const char *base, int (*fn)(const char *path, const u
 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 {
 	unsigned char sha1[20];
-	if (!read_ref(git_path("HEAD"), sha1))
+	if (!read_ref("HEAD", sha1))
 		return fn("HEAD", sha1);
 	return 0;
 }
@@ -335,7 +342,7 @@ int get_ref_sha1(const char *ref, unsigned char *sha1)
 {
 	if (check_ref_format(ref))
 		return -1;
-	return read_ref(git_path("refs/%s", ref), sha1);
+	return read_ref(mkpath("refs/%s", ref), sha1);
 }
 
 /*
@@ -416,31 +423,30 @@ static struct ref_lock *verify_lock(struct ref_lock *lock,
 	return lock;
 }
 
-static struct ref_lock *lock_ref_sha1_basic(const char *path,
+static struct ref_lock *lock_ref_sha1_basic(const char *ref,
 	int plen,
 	const unsigned char *old_sha1, int mustexist)
 {
-	const char *orig_path = path;
+	const char *orig_ref = ref;
 	struct ref_lock *lock;
 	struct stat st;
 
 	lock = xcalloc(1, sizeof(struct ref_lock));
 	lock->lock_fd = -1;
 
-	plen = strlen(path) - plen;
-	path = resolve_ref(path, lock->old_sha1, mustexist);
-	if (!path) {
+	ref = resolve_ref(ref, lock->old_sha1, mustexist);
+	if (!ref) {
 		int last_errno = errno;
 		error("unable to resolve reference %s: %s",
-			orig_path, strerror(errno));
+			orig_ref, strerror(errno));
 		unlock_ref(lock);
 		errno = last_errno;
 		return NULL;
 	}
 	lock->lk = xcalloc(1, sizeof(struct lock_file));
 
-	lock->ref_file = xstrdup(path);
-	lock->log_file = xstrdup(git_path("logs/%s", lock->ref_file + plen));
+	lock->ref_file = xstrdup(git_path("%s", ref));
+	lock->log_file = xstrdup(git_path("logs/%s", ref));
 	lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 
 	if (safe_create_leading_directories(lock->ref_file))
@@ -455,15 +461,14 @@ struct ref_lock *lock_ref_sha1(const char *ref,
 {
 	if (check_ref_format(ref))
 		return NULL;
-	return lock_ref_sha1_basic(git_path("refs/%s", ref),
+	return lock_ref_sha1_basic(mkpath("refs/%s", ref),
 		5 + strlen(ref), old_sha1, mustexist);
 }
 
 struct ref_lock *lock_any_ref_for_update(const char *ref,
 	const unsigned char *old_sha1, int mustexist)
 {
-	return lock_ref_sha1_basic(git_path("%s", ref),
-		strlen(ref), old_sha1, mustexist);
+	return lock_ref_sha1_basic(ref, strlen(ref), old_sha1, mustexist);
 }
 
 void unlock_ref(struct ref_lock *lock)