qmp: switch to the new error format on the wire

IMPORTANT: this BREAKS QMP's compatibility for the error response.

This commit changes QMP's wire protocol to make use of the simpler
error format introduced by previous commits.

There are two important (and mostly incompatible) changes:

 1. Almost all error classes have been replaced by GenericError. The
    only classes that are still supported for compatibility with
    libvirt are: CommandNotFound, DeviceNotActive, KVMMissingCap,
    DeviceNotFound and MigrationExpected

 2. The 'data' field of the error dictionary is gone

As an example, an error response like:

  { "error": { "class": "DeviceNotRemovable",
               "data": { "device": "virtio0" },
               "desc": "Device 'virtio0' is not removable" } }

Will now be emitted as:

  { "error": { "class": "GenericError",
               "desc": "Device 'virtio0' is not removable" } }

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 3 insertions, 7 deletions

diff --git a/QMP/qmp-spec.txt b/QMP/qmp-spec.txt
index 1ba916c..a277896 100644
--- a/QMP/qmp-spec.txt
+++ b/QMP/qmp-spec.txt
@@ -106,14 +106,11 @@ completed because of an error condition.
 
 The format is:
 
-{ "error": { "class": json-string, "data": json-object, "desc": json-string },
-  "id": json-value }
+{ "error": { "class": json-string, "desc": json-string }, "id": json-value }
 
  Where,
 
-- The "class" member contains the error class name (eg. "ServiceUnavailable")
-- The "data" member contains specific error data and is defined in a
-  per-command basis, it will be an empty json-object if the error has no data
+- The "class" member contains the error class name (eg. "GenericError")
 - The "desc" member is a human-readable error message. Clients should
   not attempt to parse this message.
 - The "id" member contains the transaction identification associated with
@@ -173,8 +170,7 @@ S: {"return": {"enabled": true, "present": true}, "id": "example"}
 ------------------
 
 C: { "execute": }
-S: {"error": {"class": "JSONParsing", "desc": "Invalid JSON syntax", "data":
-{}}}
+S: {"error": {"class": "GenericError", "desc": "Invalid JSON syntax" } }
 
 3.5 Powerdown event
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