commit 29a242e165610df9b158bdb8d6b84e83d8733fc4
author Sam Li <faithilikerun@gmail.com> Thu Jul 27 19:58:44 2023 +0800
committer Stefan Hajnoczi <stefanha@redhat.com> Thu Jul 27 09:46:09 2023 -0400
tree 1dd81f35bad280d11b7f43445919343c21b8ea79
parent a5942c177b7bcc1357e496b7d68668befcfc2bb9

block/file-posix: fix g_file_get_contents return path

The g_file_get_contents() function returns a g_boolean. If it fails, the
returned value will be 0 instead of -1. Solve the issue by skipping
assigning ret value.

This issue was found by Matthew Rosato using virtio-blk-{pci,ccw} backed
by an NVMe partition e.g. /dev/nvme0n1p1 on s390x.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20230727115844.8480-1-faithilikerun@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/file-posix.c

diff --git a/block/file-posix.c b/block/file-posix.c
index 9e8e3d8..b16e9c2 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1232,7 +1232,6 @@
 static int get_sysfs_str_val(struct stat *st, const char *attribute,
                              char **val) {
     g_autofree char *sysfspath = NULL;
-    int ret;
     size_t len;
 
     if (!S_ISBLK(st->st_mode)) {
@@ -1242,8 +1241,7 @@
     sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/%s",
                                 major(st->st_rdev), minor(st->st_rdev),
                                 attribute);
-    ret = g_file_get_contents(sysfspath, val, &len, NULL);
-    if (ret == -1) {
+    if (!g_file_get_contents(sysfspath, val, &len, NULL)) {
         return -ENOENT;
     }
 
@@ -1253,7 +1251,7 @@
     if (*(p + len - 1) == '\n') {
         *(p + len - 1) = '\0';
     }
-    return ret;
+    return 0;
 }
 #endif