From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Tue, 30 Aug 2016 19:00:38 +0000 (+0200)
Subject: lib/loopdev: Set errno in is_loopdev on error
X-Git-Tag: v2.29-rc1~89
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=cb129d9cc4a2ae39ba2b678bc511ff81d5023850;p=thirdparty%2Futil-linux.git

lib/loopdev: Set errno in is_loopdev on error

The function is_loopdev does not set errno if the supplied string does
not reference a valid loop device. Fix this to avoid an error message
like this one:

  losetup: /: failed to use device: Success

I prefer this one:

  losetup: /: failed to use device: No such device

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
---

diff --git a/lib/loopdev.c b/lib/loopdev.c
index b3941dd142..a57e7a73b4 100644
--- a/lib/loopdev.c
+++ b/lib/loopdev.c
@@ -633,12 +633,13 @@ int is_loopdev(const char *device)
 {
 	struct stat st;
 
-	if (!device)
-		return 0;
-
-	return (stat(device, &st) == 0 &&
+	if (device && stat(device, &st) == 0 &&
 		S_ISBLK(st.st_mode) &&
-		major(st.st_rdev) == LOOPDEV_MAJOR);
+		major(st.st_rdev) == LOOPDEV_MAJOR)
+		return 1;
+
+	errno = ENODEV;
+	return 0;
 }
 
 /*