nbd: Add some error case testing to iotests 223

Testing success paths is important, but it's also nice to highlight
expected failure handling, to show that we don't crash, and so that
upcoming tests that change behavior can demonstrate the resulting
effects on error paths.

Add the following errors:
Attempting to export without a running server
Attempting to start a second server
Attempting to export a bad node name
Attempting to export a name that is already exported
Attempting to export an enabled bitmap
Attempting to remove an already removed export
Attempting to quit server a second time

All of these properly complain except for a second server-stop,
which will be fixed next.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-2-eblake@redhat.com>
Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

tests/qemu-iotests/223

@@ -107,6 +107,7 @@ echo
 
 _launch_qemu 2> >(_filter_nbd)
 
+# Intentionally provoke some errors as well, to check error handling
 silent=
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"qmp_capabilities"}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"blockdev-add",
@@ -114,17 +115,28 @@ _send_qemu_cmd $QEMU_HANDLE '{"execute":"blockdev-add",
     "file":{"driver":"file", "filename":"'"$TEST_IMG"'"}}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"block-dirty-bitmap-disable",
   "arguments":{"node":"n", "name":"b"}}' "return"
-_send_qemu_cmd $QEMU_HANDLE '{"execute":"block-dirty-bitmap-disable",
-  "arguments":{"node":"n", "name":"b2"}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
+  "arguments":{"device":"n"}}' "error" # Attempt add without server
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-start",
   "arguments":{"addr":{"type":"unix",
     "data":{"path":"'"$TEST_DIR/nbd"'"}}}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-start",
+  "arguments":{"addr":{"type":"unix",
+    "data":{"path":"'"$TEST_DIR/nbd"1'"}}}}' "error" # Attempt second server
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
   "arguments":{"device":"n"}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
+  "arguments":{"device":"nosuch"}}' "error" # Attempt to export missing node
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
+  "arguments":{"device":"n"}}' "error" # Attempt to export same name twice
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"x-nbd-server-add-bitmap",
   "arguments":{"name":"n", "bitmap":"b"}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
   "arguments":{"device":"n", "name":"n2"}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"x-nbd-server-add-bitmap",
+  "arguments":{"name":"n2", "bitmap":"b2"}}' "error" # Attempt enabled bitmap
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"block-dirty-bitmap-disable",
+  "arguments":{"node":"n", "name":"b2"}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"x-nbd-server-add-bitmap",
   "arguments":{"name":"n2", "bitmap":"b2"}}' "return"
 
@@ -157,7 +169,10 @@ _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-remove",
   "arguments":{"name":"n"}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-remove",
   "arguments":{"name":"n2"}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-remove",
+  "arguments":{"name":"n2"}}' "error" # Attempt duplicate clean
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-stop"}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-stop"}' "return" # Oops
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"quit"}' "return"
 
 # success, all done

tests/qemu-iotests/223.out

@@ -27,10 +27,15 @@ wrote 2097152/2097152 bytes at offset 2097152
 {"return": {}}
 {"return": {}}
 {"return": {}}
+{"error": {"class": "GenericError", "desc": "NBD server not running"}}
 {"return": {}}
+{"error": {"class": "GenericError", "desc": "NBD server already running"}}
 {"return": {}}
+{"error": {"class": "GenericError", "desc": "Cannot find device=nosuch nor node_name=nosuch"}}
+{"error": {"class": "GenericError", "desc": "NBD server already has export named 'n'"}}
 {"return": {}}
 {"return": {}}
+{"error": {"class": "GenericError", "desc": "Bitmap 'b2' is enabled"}}
 {"return": {}}
 {"return": {}}
 
@@ -62,6 +67,8 @@ read 2097152/2097152 bytes at offset 2097152
 
 {"return": {}}
 {"return": {}}
+{"error": {"class": "GenericError", "desc": "Export 'n2' is not found"}}
+{"return": {}}
 {"return": {}}
 {"return": {}}
 *** done