1 file changed, 6 insertions, 7 deletions
diff --git a/source/cache.c b/source/cache.c
index 82b3aad..9594fd6 100644
--- a/source/cache.c
+++ b/source/cache.c
@@ -13,6 +13,7 @@
 #include "cgit.h"
 #include "html.h"
 #include "shared.h"
+#include <sys/file.h>
 #ifdef HAVE_LINUX_SENDFILE
 #include <sys/sendfile.h>
 #endif
@@ -232,18 +233,16 @@ static int close_lock(struct cache_slot *slot)
  */
 static int lock_slot(struct cache_slot *slot)
 {
-	struct flock lock = {
-		.l_type = F_WRLCK,
-		.l_whence = SEEK_SET,
-		.l_start = 0,
-		.l_len = 0,
-	};
 	struct stat held, named;
 
 	slot->lock_fd = open(slot->lock_path, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
 	if (slot->lock_fd == -1)
 		return errno;
-	if (fcntl(slot->lock_fd, F_SETLK, &lock) < 0) {
+	// An flock rather than a POSIX record lock. The descriptor is put on
+	// stdout for the fill, and a record lock is dropped as soon as any
+	// descriptor on the file closes, which an exec filter does to stdout,
+	// while an flock holds until the last descriptor closes.
+	if (flock(slot->lock_fd, LOCK_EX | LOCK_NB) < 0) {
 		int saved_errno = errno;
 		close(slot->lock_fd);
 		slot->lock_fd = -1;