Be more careful about updating refs

[thirdparty/git.git] / refs.c

diff --git a/refs.c b/refs.c
index 58f6d173970bcd3c1e540b7cff04d1613fce3692..c3ffe0393b3c5b884422d3f9389b6c89ab6fd0df 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1119,10 +1119,16 @@ static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
        return 0;
 }
 
+static int is_branch(const char *refname)
+{
+       return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
+}
+
 int write_ref_sha1(struct ref_lock *lock,
        const unsigned char *sha1, const char *logmsg)
 {
        static char term = '\n';
+       struct object *o;
 
        if (!lock)
                return -1;
@@ -1130,6 +1136,19 @@ int write_ref_sha1(struct ref_lock *lock,
                unlock_ref(lock);
                return 0;
        }
+       o = parse_object(sha1);
+       if (!o) {
+               error("Trying to write ref %s with nonexistant object %s",
+                       lock->ref_name, sha1_to_hex(sha1));
+               unlock_ref(lock);
+               return -1;
+       }
+       if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
+               error("Trying to write non-commit object %s to branch %s",
+                       sha1_to_hex(sha1), lock->ref_name);
+               unlock_ref(lock);
+               return -1;
+       }
        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
            write_in_full(lock->lock_fd, &term, 1) != 1
                || close(lock->lock_fd) < 0) {