unicorn/qemu/qapi/qapi-visit-core.c
Eric Blake 2f42c2c195
qapi: Change visit_type_FOO() to no longer return partial objects
Returning a partial object on error is an invitation for a careless
caller to leak memory. We already fixed things in an earlier
patch to guarantee NULL if visit_start fails ("qapi: Guarantee
NULL obj on input visitor callback error"), but that does not
help the case where visit_start succeeds but some other failure
happens before visit_end, such that we leak a partially constructed
object outside visit_type_FOO(). As no one outside the testsuite
was actually relying on these semantics, it is cleaner to just
document and guarantee that ALL pointer-based visit_type_FOO()
functions always leave a safe value in *obj during an input visitor
(either the new object on success, or NULL if an error is
encountered), so callers can now unconditionally use
qapi_free_FOO() to clean up regardless of whether an error occurred.

The decision is done by adding visit_is_input(), then updating the
generated code to check if additional cleanup is needed based on
the type of visitor in use.

Note that we still leave *obj unchanged after a scalar-based
visit_type_FOO(); I did not feel like auditing all uses of
visit_type_Enum() to see if the callers would tolerate a specific
sentinel value (not to mention having to decide whether it would
be better to use 0 or ENUM__MAX as that sentinel).

Backports commit 68ab47e4b4ecc1c4649362b8cc1e49794d1a6537 from qemu
2018-02-23 19:53:17 -05:00

321 lines
7.8 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_check_struct(Visitor *v, Error **errp)
{
if (v->check_struct) {
v->check_struct(v, errp);
}
}
void visit_end_struct(Visitor *v)
{
v->end_struct(v);
}
void visit_start_list(Visitor *v, const char *name, GenericList **list,
size_t size, Error **errp)
{
Error *err = NULL;
assert(!list || size >= sizeof(GenericList));
v->start_list(v, name, list, size, &err);
if (list && v->type == VISITOR_INPUT) {
assert(!(err && *list));
}
error_propagate(errp, err);
}
GenericList *visit_next_list(Visitor *v, GenericList *tail, size_t size)
{
assert(tail && size >= sizeof(GenericList));
return v->next_list(v, tail, 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)
{
assert(obj && size >= sizeof(GenericAlternate));
assert(v->type != VISITOR_OUTPUT || *obj);
if (v->start_alternate) {
v->start_alternate(v, name, obj, size, promote_int, errp);
}
}
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;
}
bool visit_is_input(Visitor *v)
{
return v->type == VISITOR_INPUT;
}
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, const char *name, uint64_t *obj,
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, name, &value, 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, name, &value, 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, name, &value, 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, const char *name, int64_t *obj,
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, name, &value, 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, name, &value, 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, name, &value, 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 = (int)value;
}
void visit_type_enum(Visitor *v, const char *name, int *obj,
const char *const strings[], Error **errp)
{
assert(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);
}
}