When external_snapshot_abort() rejects a BlockDriverState without a
medium, it creates an error like this:
error_setg(errp, "Device '%s' has no medium", device);
Trouble is @device can be null. My system formats null as "(null)",
but other systems might crash. Reproducer:
1. Create a block device without a medium
-> {"execute": "blockdev-add", "arguments": {"driver": "host_cdrom",
"node-name": "blk0", "filename": "/dev/sr0"}}
<- {"return": {}}
3. Attempt to snapshot it
-> {"execute":"blockdev-snapshot-sync", "arguments": { "node-name": "blk0",
"snapshot-file":"/tmp/foo.qcow2","format":"qcow2"}}
<- {"error": {"class": "GenericError", "desc": "Device '(null)' has no
medium"}}
Broken when commit 0901f67ecdb made @device optional.
Use bdrv_get_device_or_node_name() instead. Now it fails as it
should:
<- {"error": {"class": "GenericError", "desc": "Device 'blk0' has no
medium"}}
Fixes: 0901f67ecdb7 (qmp: Allow to take external snapshots on bs graphs node.)
Signed-off-by: Markus Armbruster
---
blockdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/blockdev.c b/blockdev.c
index d8fb3399f5..057601dcf0 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1395,7 +1395,8 @@ static void external_snapshot_action(TransactionAction
*action,
bdrv_drained_begin(state->old_bs);
if (!bdrv_is_inserted(state->old_bs)) {
-error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
+error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM,
+ bdrv_get_device_or_node_name(state->old_bs));
return;
}
--
2.44.0
