Simplify the code around qmp_dispatch():
- rely on qmp_dispatch/check_obj() for message checking
- have a single send_response() point
- constify send_response() argument

It changes a couple of error messages:

* When @req isn't a dictionary, from
    Invalid JSON syntax
  to
    QMP input must be a JSON object

* When @req lacks member "execute", from
    this feature or command is not currently supported
  to
    QMP input lacks member 'execute'

CC: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 qga/main.c | 47 +++++++++--------------------------------------
 1 file changed, 9 insertions(+), 38 deletions(-)

diff --git a/qga/main.c b/qga/main.c
index 87a0711c14..c0d77c79c4 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -523,15 +523,15 @@ fail:
 #endif
 }
 
-static int send_response(GAState *s, QDict *payload)
+static int send_response(GAState *s, const QDict *rsp)
 {
     const char *buf;
     QString *payload_qstr, *response_qstr;
     GIOStatus status;
 
-    g_assert(payload && s->channel);
+    g_assert(rsp && s->channel);
 
-    payload_qstr = qobject_to_json(QOBJECT(payload));
+    payload_qstr = qobject_to_json(QOBJECT(rsp));
     if (!payload_qstr) {
         return -EINVAL;
     }
@@ -557,53 +557,24 @@ static int send_response(GAState *s, QDict *payload)
     return 0;
 }
 
-static void process_command(GAState *s, QDict *req)
-{
-    QDict *rsp;
-    int ret;
-
-    g_assert(req);
-    g_debug("processing command");
-    rsp = qmp_dispatch(&ga_commands, QOBJECT(req), false);
-    if (rsp) {
-        ret = send_response(s, rsp);
-        if (ret < 0) {
-            g_warning("error sending response: %s", strerror(-ret));
-        }
-        qobject_unref(rsp);
-    }
-}
-
 /* handle requests/control events coming in over the channel */
 static void process_event(void *opaque, QObject *obj, Error *err)
 {
     GAState *s = opaque;
-    QDict *req, *rsp;
+    QDict *rsp;
     int ret;
 
     g_debug("process_event: called");
     assert(!obj != !err);
     if (err) {
-        goto err;
-    }
-    req = qobject_to(QDict, obj);
-    if (!req) {
-        error_setg(&err, "Input must be a JSON object");
-        goto err;
-    }
-    if (!qdict_haskey(req, "execute")) {
-        g_warning("unrecognized payload format");
-        error_setg(&err, QERR_UNSUPPORTED);
-        goto err;
+        rsp = qmp_error_response(err);
+        goto end;
     }
 
-    process_command(s, req);
-    qobject_unref(obj);
-    return;
+    g_debug("processing command");
+    rsp = qmp_dispatch(&ga_commands, obj, false);
 
-err:
-    g_warning("failed to parse event: %s", error_get_pretty(err));
-    rsp = qmp_error_response(err);
+end:
     ret = send_response(s, rsp);
     if (ret < 0) {
         g_warning("error sending error response: %s", strerror(-ret));
-- 
2.21.0.rc1

On 2/20/19 9:42 AM, Marc-André Lureau wrote:
> Simplify the code around qmp_dispatch():
> - rely on qmp_dispatch/check_obj() for message checking
> - have a single send_response() point
> - constify send_response() argument
> 
> It changes a couple of error messages:
> 
> * When @req isn't a dictionary, from
>     Invalid JSON syntax
>   to
>     QMP input must be a JSON object
> 
> * When @req lacks member "execute", from
>     this feature or command is not currently supported
>   to
>     QMP input lacks member 'execute'
> 
> CC: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  qga/main.c | 47 +++++++++--------------------------------------
>  1 file changed, 9 insertions(+), 38 deletions(-)

Nice simplification.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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