1 files changed, 14 insertions, 1 deletions

diff --git a/cache.c b/cache.c
index 801e63f..900b161 100644
--- a/cache.c
+++ b/cache.c
@@ -161,10 +161,23 @@ static int close_lock(struct cache_slot *slot)
  */
 static int lock_slot(struct cache_slot *slot)
 {
-        slot->lock_fd = open(slot->lock_name, O_RDWR | O_CREAT | O_EXCL,
+        struct flock lock = {
+                .l_type = F_WRLCK,
+                .l_whence = SEEK_SET,
+                .l_start = 0,
+                .l_len = 0,
+        };
+
+        slot->lock_fd = open(slot->lock_name, O_RDWR | O_CREAT,
                              S_IRUSR | S_IWUSR);
         if (slot->lock_fd == -1)
                 return errno;
+        if (fcntl(slot->lock_fd, F_SETLK, &lock) < 0) {
+                int saved_errno = errno;
+                close(slot->lock_fd);
+                slot->lock_fd = -1;
+                return saved_errno;
+        }
         if (xwrite(slot->lock_fd, slot->key, slot->keylen + 1) < 0)
                 return errno;
         return 0;