From edc7b411f0e0d7f28b226714a8bbfe10ed2bdbd0 Mon Sep 17 00:00:00 2001
From: Demi Marie Obenour <demi@invisiblethingslab.com>
Date: Wed, 22 Feb 2023 10:38:11 -0500
Subject: [PATCH] Retry LOOP_CONFIGURE as well as open

LOOP_CONFIGURE can also fail transiently and need to be retried.
---
 not-script/not-script.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/not-script/not-script.c b/not-script/not-script.c
index 7acc9d97..9138ffb1 100644
--- a/not-script/not-script.c
+++ b/not-script/not-script.c
@@ -49,7 +49,7 @@ static int setup_loop(struct loop_context *ctx,
                       uint64_t offset,
                       uint64_t sizelimit,
                       bool writable, bool autoclear) {
-    int dev_file = -1, status;
+    int dev_file = -1;
 
     struct loop_config config = {
         .fd = fd,
@@ -62,6 +62,9 @@ static int setup_loop(struct loop_context *ctx,
     };
 
     for (int retry_count = 0; retry_count < 5 /* arbitrary */; retry_count++) {
+        int old_errno;
+        int status;
+
         if ((status = ioctl(ctx->fd, LOOP_CTL_GET_FREE)) == -1)
             return -errno;
         dev_file = open_loop_dev(status, writable);
@@ -70,9 +73,11 @@ static int setup_loop(struct loop_context *ctx,
             case 0:
                 return dev_file;
             case -1:
+                old_errno = errno;
                 if (close(dev_file))
                     abort(); /* cannot happen on Linux */
-                return -1;
+                errno = old_errno;
+                break;
             default:
                 abort();
             }