[Qemu-devel] [PATCH] qapi: Reintroduce CommandDisabled error class

[Michal Privoznik]

If there was a disabled command, then qemu-ga used to report
CommandDisabled error class (among with human readable
description). This changed in v1.2.0-rc0~28^2~16 in favor of
GenericError class. While the change might work for other
classes, this one should not have been dropped because it helps
callers distinguish the root cause of the error.

A bit of background: up until very recently libvirt used qemu-ga
in all or nothing way. It didn't care why a qemu-ga command
failed. But very recently a new API was introduced which
implements 'best effort' approach (in some cases) and thus
libvirt must differentiate between: {CommandNotFound,
CommandDisabled} and some generic error. While the former classes
mean the API can issue some other commands the latter raises a
red flag causing the API to fail.

This reverts df1e608a01 partially.

Signed-off-by: Michal Privoznik <address@hidden>
---
 include/qapi/error.h | 1 +
 qapi/error.json      | 4 +++-
 qapi/qmp-dispatch.c  | 5 +++--
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/qapi/error.h b/include/qapi/error.h
index 3f95141a01..7116b86a92 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -129,6 +129,7 @@
 typedef enum ErrorClass {
     ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERICERROR,
     ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMANDNOTFOUND,
+    ERROR_CLASS_COMMAND_DISABLED = QAPI_ERROR_CLASS_COMMANDDISABLED,
     ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICENOTACTIVE,
     ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICENOTFOUND,
     ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVMMISSINGCAP,
diff --git a/qapi/error.json b/qapi/error.json
index 3fad08f506..334d481399 100644
--- a/qapi/error.json
+++ b/qapi/error.json
@@ -14,6 +14,8 @@
 #
 # @CommandNotFound: the requested command has not been found
 #
+# @CommandDisabled: the requested command has been disabled
+#
 # @DeviceNotActive: a device has failed to be become active
 #
 # @DeviceNotFound: the requested device has not been found
@@ -25,5 +27,5 @@
 ##
 { 'enum': 'QapiErrorClass',
   # Keep this in sync with ErrorClass in error.h
-  'data': [ 'GenericError', 'CommandNotFound',
+  'data': [ 'GenericError', 'CommandNotFound', 'CommandDisabled',
             'DeviceNotActive', 'DeviceNotFound', 'KVMMissingCap' ] }
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 3037d353a4..913b3363cb 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -104,8 +104,9 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, 
QObject *request,
         return NULL;
     }
     if (!cmd->enabled) {
-        error_setg(errp, "The command %s has been disabled for this instance",
-                   command);
+        error_set(errp, ERROR_CLASS_COMMAND_DISABLED,
+                  "The command %s has been disabled for this instance",
+                  command);
         return NULL;
     }
     if (oob && !(cmd->options & QCO_ALLOW_OOB)) {
-- 
2.21.0