qemu/qapi/qapi-visit-core.c
Eric Blake 3bc97fd592 qapi: Add visit_type_null() visitor
Right now, qmp-output-visitor happens to produce a QNull result
if nothing is actually visited between the creation of the visitor
and the request for the resulting QObject.  A stronger protocol
would require that a QMP output visit MUST visit something.  But
to still be able to produce a JSON 'null' output, we need a new
visitor function that states our intentions.  Yes, we could say
that such a visit must go through visit_type_any(), but that
feels clunky.

So this patch introduces the new visit_type_null() interface and
its no-op interface in the dealloc visitor, and stubs in the
qmp visitors (the next patch will finish the implementation).
For the visitors that will not implement the callback, document
the situation. The code in qapi-visit-core unconditionally
dereferences the callback pointer, so that a segfault will inform
a developer if they need to implement the callback for their
choice of visitor.

Note that JSON has a primitive null type, with the single value
null; likewise with the QNull type for QObject; but for QAPI,
we just have the 'null' value without a null type.  We may
eventually want to add more support in QAPI for null (most likely,
we'd use it via an alternate type that permits 'null' or an
object); but we'll create that usage when we need it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-15-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-05-12 09:47:54 +02:00

309 lines
7.6 KiB
C

/*
* Core Definitions for QAPI Visitor Classes
*
* Copyright (C) 2012-2016 Red Hat, Inc.
* 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/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "qapi/qmp/qobject.h"
#include "qapi/qmp/qerror.h"
#include "qapi/visitor.h"
#include "qapi/visitor-impl.h"
void visit_start_struct(Visitor *v, const char *name, void **obj,
size_t size, Error **errp)
{
Error *err = NULL;
if (obj) {
assert(size);
assert(v->type != VISITOR_OUTPUT || *obj);
}
v->start_struct(v, name, obj, size, &err);
if (obj && v->type == VISITOR_INPUT) {
assert(!err != !*obj);
}
error_propagate(errp, err);
}
void visit_end_struct(Visitor *v, Error **errp)
{
v->end_struct(v, errp);
}
void visit_start_list(Visitor *v, const char *name, Error **errp)
{
v->start_list(v, name, errp);
}
GenericList *visit_next_list(Visitor *v, GenericList **list, size_t size)
{
assert(list && size >= sizeof(GenericList));
return v->next_list(v, list, size);
}
void visit_end_list(Visitor *v)
{
v->end_list(v);
}
void visit_start_alternate(Visitor *v, const char *name,
GenericAlternate **obj, size_t size,
bool promote_int, Error **errp)
{
Error *err = NULL;
assert(obj && size >= sizeof(GenericAlternate));
assert(v->type != VISITOR_OUTPUT || *obj);
if (v->start_alternate) {
v->start_alternate(v, name, obj, size, promote_int, &err);
}
if (v->type == VISITOR_INPUT) {
assert(v->start_alternate && !err != !*obj);
}
error_propagate(errp, err);
}
void visit_end_alternate(Visitor *v)
{
if (v->end_alternate) {
v->end_alternate(v);
}
}
bool visit_optional(Visitor *v, const char *name, bool *present)
{
if (v->optional) {
v->optional(v, name, present);
}
return *present;
}
void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
{
assert(obj);
v->type_int64(v, name, obj, errp);
}
static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
uint64_t max, const char *type, Error **errp)
{
Error *err = NULL;
uint64_t value = *obj;
v->type_uint64(v, name, &value, &err);
if (err) {
error_propagate(errp, err);
} else if (value > max) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
name ? name : "null", type);
} else {
*obj = value;
}
}
void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
Error **errp)
{
uint64_t value = *obj;
visit_type_uintN(v, &value, name, UINT8_MAX, "uint8_t", errp);
*obj = value;
}
void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
Error **errp)
{
uint64_t value = *obj;
visit_type_uintN(v, &value, name, UINT16_MAX, "uint16_t", errp);
*obj = value;
}
void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
Error **errp)
{
uint64_t value = *obj;
visit_type_uintN(v, &value, name, UINT32_MAX, "uint32_t", errp);
*obj = value;
}
void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
Error **errp)
{
assert(obj);
v->type_uint64(v, name, obj, errp);
}
static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
int64_t min, int64_t max, const char *type,
Error **errp)
{
Error *err = NULL;
int64_t value = *obj;
v->type_int64(v, name, &value, &err);
if (err) {
error_propagate(errp, err);
} else if (value < min || value > max) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
name ? name : "null", type);
} else {
*obj = value;
}
}
void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp)
{
int64_t value = *obj;
visit_type_intN(v, &value, name, INT8_MIN, INT8_MAX, "int8_t", errp);
*obj = value;
}
void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
Error **errp)
{
int64_t value = *obj;
visit_type_intN(v, &value, name, INT16_MIN, INT16_MAX, "int16_t", errp);
*obj = value;
}
void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
Error **errp)
{
int64_t value = *obj;
visit_type_intN(v, &value, name, INT32_MIN, INT32_MAX, "int32_t", errp);
*obj = value;
}
void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
Error **errp)
{
assert(obj);
v->type_int64(v, name, obj, errp);
}
void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
Error **errp)
{
assert(obj);
if (v->type_size) {
v->type_size(v, name, obj, errp);
} else {
v->type_uint64(v, name, obj, errp);
}
}
void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
{
assert(obj);
v->type_bool(v, name, obj, errp);
}
void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
{
Error *err = NULL;
assert(obj);
/* TODO: Fix callers to not pass NULL when they mean "", so that we
* can enable:
assert(v->type != VISITOR_OUTPUT || *obj);
*/
v->type_str(v, name, obj, &err);
if (v->type == VISITOR_INPUT) {
assert(!err != !*obj);
}
error_propagate(errp, err);
}
void visit_type_number(Visitor *v, const char *name, double *obj,
Error **errp)
{
assert(obj);
v->type_number(v, name, obj, errp);
}
void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
{
Error *err = NULL;
assert(obj);
assert(v->type != VISITOR_OUTPUT || *obj);
v->type_any(v, name, obj, &err);
if (v->type == VISITOR_INPUT) {
assert(!err != !*obj);
}
error_propagate(errp, err);
}
void visit_type_null(Visitor *v, const char *name, Error **errp)
{
v->type_null(v, name, errp);
}
static void output_type_enum(Visitor *v, const char *name, int *obj,
const char *const strings[], Error **errp)
{
int i = 0;
int value = *obj;
char *enum_str;
while (strings[i++] != NULL);
if (value < 0 || value >= i - 1) {
error_setg(errp, QERR_INVALID_PARAMETER, name ? name : "null");
return;
}
enum_str = (char *)strings[value];
visit_type_str(v, name, &enum_str, errp);
}
static void input_type_enum(Visitor *v, const char *name, int *obj,
const char *const strings[], Error **errp)
{
Error *local_err = NULL;
int64_t value = 0;
char *enum_str;
visit_type_str(v, name, &enum_str, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
while (strings[value] != NULL) {
if (strcmp(strings[value], enum_str) == 0) {
break;
}
value++;
}
if (strings[value] == NULL) {
error_setg(errp, QERR_INVALID_PARAMETER, enum_str);
g_free(enum_str);
return;
}
g_free(enum_str);
*obj = value;
}
void visit_type_enum(Visitor *v, const char *name, int *obj,
const char *const strings[], Error **errp)
{
assert(obj && strings);
if (v->type == VISITOR_INPUT) {
input_type_enum(v, name, obj, strings, errp);
} else if (v->type == VISITOR_OUTPUT) {
output_type_enum(v, name, obj, strings, errp);
}
}