qapi: add QMP dispatch functions

Given an object recieved via QMP, this code uses the dispatch table
provided by qmp_registry.c to call the corresponding marshalling/dispatch
function and format return values/errors for delivery to the QMP.
Currently only synchronous QMP functions are supported, but this will
also be used for async QMP functions and QMP guest proxy dispatch as
well.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@gmail.com>

Makefile.objs

@@ -376,7 +376,7 @@ libcacard-y = cac.o event.o vcard.o vreader.o vcard_emul_nss.o vcard_emul_type.o
 # qapi
 
 qapi-nested-y = qapi-visit-core.o qmp-input-visitor.o qmp-output-visitor.o qapi-dealloc-visitor.o
-qapi-nested-y += qmp-registry.o
+qapi-nested-y += qmp-registry.o qmp-dispatch.o
 qapi-obj-y = $(addprefix qapi/, $(qapi-nested-y))
 
 vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)

qapi/qmp-core.h

@@ -35,5 +35,7 @@ typedef struct QmpCommand
 
 void qmp_register_command(const char *name, QmpCommandFunc *fn);
 QmpCommand *qmp_find_command(const char *name);
+QObject *qmp_dispatch(QObject *request);
 
 #endif
+

qapi/qmp-dispatch.c

@@ -0,0 +1,124 @@
+/*
+ * Core Definitions for QAPI/QMP Dispatch
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu-objects.h"
+#include "qapi/qmp-core.h"
+#include "json-parser.h"
+#include "error.h"
+#include "error_int.h"
+#include "qerror.h"
+
+static QDict *qmp_dispatch_check_obj(const QObject *request, Error **errp)
+{
+    const QDictEntry *ent;
+    const char *arg_name;
+    const QObject *arg_obj;
+    bool has_exec_key = false;
+    QDict *dict = NULL;
+
+    if (qobject_type(request) != QTYPE_QDICT) {
+        error_set(errp, QERR_QMP_BAD_INPUT_OBJECT,
+                  "request is not a dictionary");
+        return NULL;
+    }
+
+    dict = qobject_to_qdict(request);
+
+    for (ent = qdict_first(dict); ent;
+         ent = qdict_next(dict, ent)) {
+        arg_name = qdict_entry_key(ent);
+        arg_obj = qdict_entry_value(ent);
+
+        if (!strcmp(arg_name, "execute")) {
+            if (qobject_type(arg_obj) != QTYPE_QSTRING) {
+                error_set(errp, QERR_QMP_BAD_INPUT_OBJECT_MEMBER, "execute",
+                          "string");
+                return NULL;
+            }
+            has_exec_key = true;
+        } else if (strcmp(arg_name, "arguments")) {
+            error_set(errp, QERR_QMP_EXTRA_MEMBER, arg_name);
+            return NULL;
+        }
+    }
+
+    if (!has_exec_key) {
+        error_set(errp, QERR_QMP_BAD_INPUT_OBJECT, "execute");
+        return NULL;
+    }
+
+    return dict;
+}
+
+static QObject *do_qmp_dispatch(QObject *request, Error **errp)
+{
+    const char *command;
+    QDict *args, *dict;
+    QmpCommand *cmd;
+    QObject *ret = NULL;
+
+
+    dict = qmp_dispatch_check_obj(request, errp);
+    if (!dict || error_is_set(errp)) {
+        return NULL;
+    }
+
+    command = qdict_get_str(dict, "execute");
+    cmd = qmp_find_command(command);
+    if (cmd == NULL) {
+        error_set(errp, QERR_COMMAND_NOT_FOUND, command);
+        return NULL;
+    }
+
+    if (!qdict_haskey(dict, "arguments")) {
+        args = qdict_new();
+    } else {
+        args = qdict_get_qdict(dict, "arguments");
+        QINCREF(args);
+    }
+
+    switch (cmd->type) {
+    case QCT_NORMAL:
+        cmd->fn(args, &ret, errp);
+        if (!error_is_set(errp) && ret == NULL) {
+            ret = QOBJECT(qdict_new());
+        }
+        break;
+    }
+
+    QDECREF(args);
+
+    return ret;
+}
+
+QObject *qmp_dispatch(QObject *request)
+{
+    Error *err = NULL;
+    QObject *ret;
+    QDict *rsp;
+
+    ret = do_qmp_dispatch(request, &err);
+
+    rsp = qdict_new();
+    if (err) {
+        qdict_put_obj(rsp, "error", error_get_qobject(err));
+        error_free(err);
+    } else if (ret) {
+        qdict_put_obj(rsp, "return", ret);
+    } else {
+        QDECREF(rsp);
+        return NULL;
+    }
+
+    return QOBJECT(rsp);
+}