migration: introduce migrate_params_check()

Helper to check the parameters. Abstracted from
qmp_migrate_set_parameters().

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1500349150-13240-5-git-send-email-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/migration.c

@@ -644,64 +644,86 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 }
 
-void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
+/*
+ * Check whether the parameters are valid. Error will be put into errp
+ * (if provided). Return true if valid, otherwise false.
+ */
+static bool migrate_params_check(MigrationParameters *params, Error **errp)
 {
-    MigrationState *s = migrate_get_current();
-
     if (params->has_compress_level &&
         (params->compress_level < 0 || params->compress_level > 9)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "compress_level",
                    "is invalid, it should be in the range of 0 to 9");
-        return;
+        return false;
     }
+
     if (params->has_compress_threads &&
         (params->compress_threads < 1 || params->compress_threads > 255)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                    "compress_threads",
                    "is invalid, it should be in the range of 1 to 255");
-        return;
+        return false;
     }
+
     if (params->has_decompress_threads &&
         (params->decompress_threads < 1 || params->decompress_threads > 255)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                    "decompress_threads",
                    "is invalid, it should be in the range of 1 to 255");
-        return;
+        return false;
     }
+
     if (params->has_cpu_throttle_initial &&
         (params->cpu_throttle_initial < 1 ||
          params->cpu_throttle_initial > 99)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                    "cpu_throttle_initial",
                    "an integer in the range of 1 to 99");
-        return;
+        return false;
     }
+
     if (params->has_cpu_throttle_increment &&
         (params->cpu_throttle_increment < 1 ||
          params->cpu_throttle_increment > 99)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                    "cpu_throttle_increment",
                    "an integer in the range of 1 to 99");
-        return;
+        return false;
     }
+
     if (params->has_max_bandwidth &&
         (params->max_bandwidth < 0 || params->max_bandwidth > SIZE_MAX)) {
         error_setg(errp, "Parameter 'max_bandwidth' expects an integer in the"
                          " range of 0 to %zu bytes/second", SIZE_MAX);
-        return;
+        return false;
     }
+
     if (params->has_downtime_limit &&
         (params->downtime_limit < 0 ||
          params->downtime_limit > MAX_MIGRATE_DOWNTIME)) {
         error_setg(errp, "Parameter 'downtime_limit' expects an integer in "
                          "the range of 0 to %d milliseconds",
                          MAX_MIGRATE_DOWNTIME);
-        return;
+        return false;
     }
+
     if (params->has_x_checkpoint_delay && (params->x_checkpoint_delay < 0)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "x_checkpoint_delay",
                     "is invalid, it should be positive");
+        return false;
+    }
+
+    return true;
+}
+
+void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
+{
+    MigrationState *s = migrate_get_current();
+
+    if (!migrate_params_check(params, errp)) {
+        /* Invalid parameter */
+        return;
     }
 
     if (params->has_compress_level) {