lockfile: fix buffer overflow in path handling
[git/git.git] / lockfile.c
index c6fb77b..8fbcb6a 100644 (file)
@@ -124,15 +124,17 @@ static char *resolve_symlink(char *p, size_t s)
 
 static int lock_file(struct lock_file *lk, const char *path, int flags)
 {
-       if (strlen(path) >= sizeof(lk->filename))
-               return -1;
-       strcpy(lk->filename, path);
        /*
         * subtract 5 from size to make sure there's room for adding
         * ".lock" for the lock file name
         */
+       static const size_t max_path_len = sizeof(lk->filename) - 5;
+
+       if (strlen(path) >= max_path_len)
+               return -1;
+       strcpy(lk->filename, path);
        if (!(flags & LOCK_NODEREF))
-               resolve_symlink(lk->filename, sizeof(lk->filename)-5);
+               resolve_symlink(lk->filename, max_path_len);
        strcat(lk->filename, ".lock");
        lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
        if (0 <= lk->fd) {