[dm-devel] [PATCH 20/21] libmultipath: dm_get_uuid(): return emtpy UUID for non-existing maps

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

libdevmapper will most probably not return a UUID for non-existing
maps anyway. But it's cheap to double-check here.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 libmultipath/devmapper.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 248c373..9be82f4 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -706,12 +706,16 @@ dm_get_prefixed_uuid(const char *name, char *uuid, int uuid_len)
 {
 	struct dm_task *dmt;
 	const char *uuidtmp;
+	struct dm_info info;
 	int r = 1;
 
 	dmt = libmp_dm_task_create(DM_DEVICE_INFO);
 	if (!dmt)
 		return 1;
 
+	if (uuid_len > 0)
+		uuid[0] = '\0';
+
 	if (!dm_task_set_name (dmt, name))
 		goto uuidout;
 
@@ -720,11 +724,13 @@ dm_get_prefixed_uuid(const char *name, char *uuid, int uuid_len)
 		goto uuidout;
 	}
 
+	if (!dm_task_get_info(dmt, &info) ||
+	    !info.exists)
+		goto uuidout;
+
 	uuidtmp = dm_task_get_uuid(dmt);
 	if (uuidtmp)
 		strlcpy(uuid, uuidtmp, uuid_len);
-	else
-		uuid[0] = '\0';
 
 	r = 0;
 uuidout:
-- 
2.41.0