assume unchanged git: diff-index fix.

[git.git] / update-ref.c

diff --git a/update-ref.c b/update-ref.c
index 127ef99..ba4bf51 100644 (file)
--- a/update-ref.c
+++ b/update-ref.c
@@ -3,61 +3,29 @@
 
 static const char git_update_ref_usage[] = "git-update-ref <refname> <value> [<oldval>]";
 
-#define MAXDEPTH 5
-
-const char *resolve_ref(const char *path, unsigned char *sha1)
+static int re_verify(const char *path, unsigned char *oldsha1, unsigned char *currsha1)
 {
-       int depth = MAXDEPTH, len;
-       char buffer[256];
-
-       for (;;) {
-               struct stat st;
-               int fd;
-
-               if (--depth < 0)
-                       return NULL;
-
-               /* Special case: non-existing file */
-               if (lstat(path, &st) < 0) {
-                       if (errno != ENOENT)
-                               return NULL;
-                       memset(sha1, 0, 20);
-                       return path;
-               }
-
-               /* 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);
-                               continue;
-                       }
-               }
-
-               /*
-                * Anything else, just open it and try to use it as
-                * a ref
-                */
-               fd = open(path, O_RDONLY);
-               if (fd < 0)
-                       return NULL;
-               len = read(fd, buffer, sizeof(buffer)-1);
-               close(fd);
-               break;
-       }
-       if (len < 40 || get_sha1_hex(buffer, sha1))
-               return NULL;
-       return path;
+       char buf[40];
+       int fd = open(path, O_RDONLY), nr;
+       if (fd < 0)
+               return -1;
+       nr = read(fd, buf, 40);
+       close(fd);
+       if (nr != 40 || get_sha1_hex(buf, currsha1) < 0)
+               return -1;
+       return memcmp(oldsha1, currsha1, 20) ? -1 : 0;
 }
 
 int main(int argc, char **argv)
 {
        char *hex;
-       const char *refname, *value, *oldval, *path, *lockpath;
+       const char *refname, *value, *oldval, *path;
+       char *lockpath;
        unsigned char sha1[20], oldsha1[20], currsha1[20];
        int fd, written;
 
        setup_git_directory();
+       git_config(git_default_config);
        if (argc < 3 || argc > 4)
                usage(git_update_ref_usage);
 
@@ -70,19 +38,21 @@ int main(int argc, char **argv)
        if (oldval && get_sha1(oldval, oldsha1) < 0)
                die("%s: not a valid old SHA1", oldval);
 
-       path = resolve_ref(git_path("%s", refname), currsha1);
+       path = resolve_ref(git_path("%s", refname), currsha1, !!oldval);
        if (!path)
                die("No such ref: %s", refname);
 
        if (oldval) {
                if (memcmp(currsha1, oldsha1, 20))
-                       die("Ref %s changed to %s", refname, sha1_to_hex(currsha1));
+                       die("Ref %s is at %s but expected %s", refname, sha1_to_hex(currsha1), sha1_to_hex(oldsha1));
                /* Nothing to do? */
                if (!memcmp(oldsha1, sha1, 20))
                        exit(0);
        }
        path = strdup(path);
        lockpath = mkpath("%s.lock", path);
+       if (safe_create_leading_directories(lockpath) < 0)
+               die("Unable to create all of %s", lockpath);
 
        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
        if (fd < 0)
@@ -97,12 +67,16 @@ int main(int argc, char **argv)
        }
 
        /*
-        * FIXME!
-        *
-        * We should re-read the old ref here, and re-verify that it
-        * matches "oldsha1". Otherwise there's a small race.
+        * Re-read the ref after getting the lock to verify
         */
+       if (oldval && re_verify(path, oldsha1, currsha1) < 0) {
+               unlink(lockpath);
+               die("Ref lock failed");
+       }
 
+       /*
+        * Finally, replace the old ref with the new one
+        */
        if (rename(lockpath, path) < 0) {
                unlink(lockpath);
                die("Unable to create %s", path);