[PATCH] Allow reading "symbolic refs" that point to other refs

[git.git] / refs.c

diff --git a/refs.c b/refs.c
index 1610180..d4f3612 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -2,17 +2,43 @@
 #include "cache.h"
 
 #include <errno.h>
+#include <ctype.h>
 
-static int read_ref(const char *refname, unsigned char *sha1)
+/* We allow "recursive" symbolic refs. Only within reason, though */
+#define MAXDEPTH 5
+
+int read_ref(const char *filename, unsigned char *sha1)
 {
-       int ret = -1;
-       int fd = open(git_path("%s", refname), O_RDONLY);
+       int depth = 0;
+       int ret = -1, fd;
+
+       while ((fd = open(filename, O_RDONLY)) >= 0) {
+               char buffer[256];
+               int len = read(fd, buffer, sizeof(buffer)-1);
 
-       if (fd >= 0) {
-               char buffer[60];
-               if (read(fd, buffer, sizeof(buffer)) >= 40)
-                       ret = get_sha1_hex(buffer, sha1);
                close(fd);
+               if (len < 0)
+                       break;
+
+               buffer[len] = 0;
+               while (len && isspace(buffer[len-1]))
+                       buffer[--len] = 0;
+
+               if (!strncmp(buffer, "ref:", 4)) {
+                       char *buf;
+                       if (depth > MAXDEPTH)
+                               break;
+                       depth++;
+                       buf = buffer + 4;
+                       len -= 4;
+                       while (len && isspace(*buf))
+                               buf++, len--;
+                       filename = git_path("%.*s", len, buf);
+                       continue;
+               }
+               if (len >= 40)
+                       ret = get_sha1_hex(buffer, sha1);
+               break;
        }
        return ret;
 }
@@ -54,7 +80,7 @@ static int do_for_each_ref(const char *base, int (*fn)(const char *path, const u
                                        break;
                                continue;
                        }
-                       if (read_ref(path, sha1) < 0)
+                       if (read_ref(git_path("%s", path), sha1) < 0)
                                continue;
                        if (!has_sha1_file(sha1))
                                continue;
@@ -71,7 +97,7 @@ 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("HEAD", sha1))
+       if (!read_ref(git_path("HEAD"), sha1))
                return fn("HEAD", sha1);
        return 0;
 }
@@ -101,33 +127,14 @@ static char *ref_lock_file_name(const char *ref)
        return ret;
 }
 
-static int read_ref_file(const char *filename, unsigned char *sha1) {
-       int fd = open(filename, O_RDONLY);
-       char hex[41];
-       if (fd < 0) {
-               return error("Couldn't open %s\n", filename);
-       }
-       if ((read(fd, hex, 41) < 41) ||
-           (hex[40] != '\n') ||
-           get_sha1_hex(hex, sha1)) {
-               error("Couldn't read a hash from %s\n", filename);
-               close(fd);
-               return -1;
-       }
-       close(fd);
-       return 0;
-}
-
 int get_ref_sha1(const char *ref, unsigned char *sha1)
 {
-       char *filename;
-       int retval;
+       const char *filename;
+
        if (check_ref_format(ref))
                return -1;
-       filename = ref_file_name(ref);
-       retval = read_ref_file(filename, sha1);
-       free(filename);
-       return retval;
+       filename = git_path("refs/%s", ref);
+       return read_ref(filename, sha1);
 }
 
 static int lock_ref_file(const char *filename, const char *lock_filename,
@@ -140,7 +147,7 @@ static int lock_ref_file(const char *filename, const char *lock_filename,
                return error("Couldn't open lock file for %s: %s",
                             filename, strerror(errno));
        }
-       retval = read_ref_file(filename, current_sha1);
+       retval = read_ref(filename, current_sha1);
        if (old_sha1) {
                if (retval) {
                        close(fd);