qapi: Generalize command policy checking

The code to check command policy can see special feature flag
'deprecated' as command flag QCO_DEPRECATED.  I want to make feature
flag 'unstable' visible there as well, so I can add policy for it.

To let me make it visible, add member @special_features (a bitset of
QapiSpecialFeature) to QmpCommand, and adjust the generator to pass it
through qmp_register_command().  Then replace "QCO_DEPRECATED in
@flags" by QAPI_DEPRECATED in @special_features", and drop
QCO_DEPRECATED.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Message-Id: <20211028102520.747396-7-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

include/qapi/qmp/dispatch.h

@@ -25,7 +25,6 @@ typedef enum QmpCommandOptions
     QCO_ALLOW_OOB             =  (1U << 1),
     QCO_ALLOW_PRECONFIG       =  (1U << 2),
     QCO_COROUTINE             =  (1U << 3),
-    QCO_DEPRECATED            =  (1U << 4),
 } QmpCommandOptions;
 
 typedef struct QmpCommand
@@ -34,6 +33,7 @@ typedef struct QmpCommand
     /* Runs in coroutine context if QCO_COROUTINE is set */
     QmpCommandFunc *fn;
     QmpCommandOptions options;
+    unsigned special_features;
     QTAILQ_ENTRY(QmpCommand) node;
     bool enabled;
     const char *disable_reason;
@@ -42,7 +42,8 @@ typedef struct QmpCommand
 typedef QTAILQ_HEAD(QmpCommandList, QmpCommand) QmpCommandList;
 
 void qmp_register_command(QmpCommandList *cmds, const char *name,
-                          QmpCommandFunc *fn, QmpCommandOptions options);
+                          QmpCommandFunc *fn, QmpCommandOptions options,
+                          unsigned special_features);
 const QmpCommand *qmp_find_command(const QmpCommandList *cmds,
                                    const char *name);
 void qmp_disable_command(QmpCommandList *cmds, const char *name,

monitor/misc.c

@@ -230,11 +230,13 @@ static void monitor_init_qmp_commands(void)
 
     qmp_init_marshal(&qmp_commands);
 
-    qmp_register_command(&qmp_commands, "device_add", qmp_device_add, 0);
+    qmp_register_command(&qmp_commands, "device_add",
+                         qmp_device_add, 0, 0);
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
+                         qmp_marshal_qmp_capabilities,
+                         QCO_ALLOW_PRECONFIG, 0);
 }
 
 /* Set the current CPU defined by the user. Callers must hold BQL. */

qapi/qmp-dispatch.c

@@ -176,7 +176,7 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
                   "The command %s has not been found", command);
         goto out;
     }
-    if (cmd->options & QCO_DEPRECATED) {
+    if (cmd->special_features & 1u << QAPI_DEPRECATED) {
         switch (compat_policy.deprecated_input) {
         case COMPAT_POLICY_INPUT_ACCEPT:
             break;

qapi/qmp-registry.c

@@ -16,7 +16,8 @@
 #include "qapi/qmp/dispatch.h"
 
 void qmp_register_command(QmpCommandList *cmds, const char *name,
-                          QmpCommandFunc *fn, QmpCommandOptions options)
+                          QmpCommandFunc *fn, QmpCommandOptions options,
+                          unsigned special_features)
 {
     QmpCommand *cmd = g_malloc0(sizeof(*cmd));
 
@@ -27,6 +28,7 @@ void qmp_register_command(QmpCommandList *cmds, const char *name,
     cmd->fn = fn;
     cmd->enabled = true;
     cmd->options = options;
+    cmd->special_features = special_features;
     QTAILQ_INSERT_TAIL(cmds, cmd, node);
 }
 

scripts/qapi/commands.py

@@ -26,6 +26,7 @@ from .gen import (
     QAPISchemaModularCVisitor,
     build_params,
     ifcontext,
+    gen_special_features,
 )
 from .schema import (
     QAPISchema,
@@ -217,9 +218,6 @@ def gen_register_command(name: str,
                          coroutine: bool) -> str:
     options = []
 
-    if 'deprecated' in [f.name for f in features]:
-        options += ['QCO_DEPRECATED']
-
     if not success_response:
         options += ['QCO_NO_SUCCESS_RESP']
     if allow_oob:
@@ -231,10 +229,11 @@ def gen_register_command(name: str,
 
     ret = mcgen('''
     qmp_register_command(cmds, "%(name)s",
-                         qmp_marshal_%(c_name)s, %(opts)s);
+                         qmp_marshal_%(c_name)s, %(opts)s, %(feats)s);
 ''',
                 name=name, c_name=c_name(name),
-                opts=' | '.join(options) or 0)
+                opts=' | '.join(options) or 0,
+                feats=gen_special_features(features))
     return ret
 
 

storage-daemon/qemu-storage-daemon.c

@@ -146,7 +146,8 @@ static void init_qmp_commands(void)
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
+                         qmp_marshal_qmp_capabilities,
+                         QCO_ALLOW_PRECONFIG, 0);
 }
 
 static int getopt_set_loc(int argc, char **argv, const char *optstring,