qapi: Factor out compat_policy_input_ok()

The code to check policy for handling deprecated input is triplicated.
Factor it out into compat_policy_input_ok() before I mess with it in
the next commit.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211028102520.747396-9-armbru@redhat.com>
[Policy code moved from qmp-dispatch.c to qapi-util.c to make visitors
link without qmp-dispatch.o]

include/qapi/compat-policy.h

@@ -13,10 +13,17 @@
 #ifndef QAPI_COMPAT_POLICY_H
 #define QAPI_COMPAT_POLICY_H
 
+#include "qapi/error.h"
 #include "qapi/qapi-types-compat.h"
 
 extern CompatPolicy compat_policy;
 
+bool compat_policy_input_ok(unsigned special_features,
+                            const CompatPolicy *policy,
+                            ErrorClass error_class,
+                            const char *kind, const char *name,
+                            Error **errp);
+
 /*
  * Create a QObject input visitor for @obj for use with QMP
  *

qapi/qapi-util.c

@@ -11,10 +11,47 @@
  */
 
 #include "qemu/osdep.h"
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qemu/ctype.h"
 #include "qapi/qmp/qerror.h"
 
+CompatPolicy compat_policy;
+
+static bool compat_policy_input_ok1(const char *adjective,
+                                    CompatPolicyInput policy,
+                                    ErrorClass error_class,
+                                    const char *kind, const char *name,
+                                    Error **errp)
+{
+    switch (policy) {
+    case COMPAT_POLICY_INPUT_ACCEPT:
+        return true;
+    case COMPAT_POLICY_INPUT_REJECT:
+        error_set(errp, error_class, "%s %s %s disabled by policy",
+                  adjective, kind, name);
+        return false;
+    case COMPAT_POLICY_INPUT_CRASH:
+    default:
+        abort();
+    }
+}
+
+bool compat_policy_input_ok(unsigned special_features,
+                            const CompatPolicy *policy,
+                            ErrorClass error_class,
+                            const char *kind, const char *name,
+                            Error **errp)
+{
+    if ((special_features & 1u << QAPI_DEPRECATED)
+        && !compat_policy_input_ok1("Deprecated",
+                                    policy->deprecated_input,
+                                    error_class, kind, name, errp)) {
+        return false;
+    }
+    return true;
+}
+
 const char *qapi_enum_lookup(const QEnumLookup *lookup, int val)
 {
     assert(val >= 0 && val < lookup->size);

qapi/qapi-visit-core.c

@@ -13,6 +13,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/visitor.h"
@@ -409,18 +410,11 @@ static bool input_type_enum(Visitor *v, const char *name, int *obj,
     }
 
     if (lookup->special_features
-        && (lookup->special_features[value] & QAPI_DEPRECATED)) {
+        && !compat_policy_input_ok(lookup->special_features[value],
-        switch (v->compat_policy.deprecated_input) {
+                                   &v->compat_policy,
-        case COMPAT_POLICY_INPUT_ACCEPT:
+                                   ERROR_CLASS_GENERIC_ERROR,
-            break;
+                                   "value", enum_str, errp)) {
-        case COMPAT_POLICY_INPUT_REJECT:
-            error_setg(errp, "Deprecated value '%s' disabled by policy",
-                       enum_str);
         return false;
-        case COMPAT_POLICY_INPUT_CRASH:
-        default:
-            abort();
-        }
     }
 
     *obj = value;

qapi/qmp-dispatch.c

@@ -26,8 +26,6 @@
 #include "qemu/coroutine.h"
 #include "qemu/main-loop.h"
 
-CompatPolicy compat_policy;
-
 Visitor *qobject_input_visitor_new_qmp(QObject *obj)
 {
     Visitor *v = qobject_input_visitor_new(obj);
@@ -176,19 +174,10 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
                   "The command %s has not been found", command);
         goto out;
     }
-    if (cmd->special_features & 1u << QAPI_DEPRECATED) {
+    if (!compat_policy_input_ok(cmd->special_features, &compat_policy,
-        switch (compat_policy.deprecated_input) {
+                                ERROR_CLASS_COMMAND_NOT_FOUND,
-        case COMPAT_POLICY_INPUT_ACCEPT:
+                                "command", command, &err)) {
-            break;
-        case COMPAT_POLICY_INPUT_REJECT:
-            error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
-                      "Deprecated command %s disabled by policy",
-                      command);
         goto out;
-        case COMPAT_POLICY_INPUT_CRASH:
-        default:
-            abort();
-        }
     }
     if (!cmd->enabled) {
         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,

qapi/qobject-input-visitor.c

@@ -14,6 +14,7 @@
 
 #include "qemu/osdep.h"
 #include <math.h>
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qapi/qobject-input-visitor.h"
 #include "qapi/visitor-impl.h"
@@ -666,21 +667,9 @@ static bool qobject_input_policy_reject(Visitor *v, const char *name,
                                         unsigned special_features,
                                         Error **errp)
 {
-    if (!(special_features & 1u << QAPI_DEPRECATED)) {
+    return !compat_policy_input_ok(special_features, &v->compat_policy,
-        return false;
+                                   ERROR_CLASS_GENERIC_ERROR,
-    }
+                                   "parameter", name, errp);
-
-    switch (v->compat_policy.deprecated_input) {
-    case COMPAT_POLICY_INPUT_ACCEPT:
-        return false;
-    case COMPAT_POLICY_INPUT_REJECT:
-        error_setg(errp, "Deprecated parameter '%s' disabled by policy",
-                   name);
-        return true;
-    case COMPAT_POLICY_INPUT_CRASH:
-    default:
-        abort();
-    }
 }
 
 static void qobject_input_free(Visitor *v)