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xen/tools/libxl/libxl_json.c
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Anthony PERARD 5265647e9a libxl: Introduce JSON parser 
We use the yajl parser, but we need to make a tree from the parse result
to use it outside the parser.

So this patch include json_object struct that is used to hold the JSON
data.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2011-09-29 16:28:24 +01:00

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/*
* Copyright (C) 2011 Citrix Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; version 2.1 only. with the special
* exception on linking described in file LICENSE.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*/
#include <assert.h>
#include <string.h>
#include <yajl/yajl_parse.h>
#include <yajl/yajl_gen.h>
#include "libxl_internal.h"
/* #define DEBUG_ANSWER */
struct libxl__yajl_ctx {
libxl__gc *gc;
yajl_handle hand;
libxl__json_object *head;
libxl__json_object *current;
#ifdef DEBUG_ANSWER
yajl_gen g;
#endif
};
#ifdef DEBUG_ANSWER
# define DEBUG_GEN_ALLOC(ctx) \
if ((ctx)->g == NULL) { \
yajl_gen_config conf = { 1, " " }; \
(ctx)->g = yajl_gen_alloc(&conf, NULL); \
}
# define DEBUG_GEN_FREE(ctx) \
if ((ctx)->g) yajl_gen_free((ctx)->g)
# define DEBUG_GEN(ctx, type) yajl_gen_##type(ctx->g)
# define DEBUG_GEN_VALUE(ctx, type, value) yajl_gen_##type(ctx->g, value)
# define DEBUG_GEN_STRING(ctx, str, n) yajl_gen_string(ctx->g, str, n)
# define DEBUG_GEN_REPORT(yajl_ctx) \
do { \
const unsigned char *buf = NULL; \
unsigned int len = 0; \
yajl_gen_get_buf((yajl_ctx)->g, &buf, &len); \
LIBXL__LOG(libxl__gc_owner((yajl_ctx)->gc), \
LIBXL__LOG_DEBUG, "response:\n%s", buf); \
yajl_gen_free((yajl_ctx)->g); \
(yajl_ctx)->g = NULL; \
} while (0)
#else
# define DEBUG_GEN_ALLOC(ctx) ((void)0)
# define DEBUG_GEN_FREE(ctx) ((void)0)
# define DEBUG_GEN(ctx, type) ((void)0)
# define DEBUG_GEN_VALUE(ctx, type, value) ((void)0)
# define DEBUG_GEN_STRING(ctx, value, lenght) ((void)0)
# define DEBUG_GEN_REPORT(ctx) ((void)0)
#endif
/*
* YAJL Helper
*/
yajl_gen_status libxl__yajl_gen_asciiz(yajl_gen hand, const char *str)
{
return yajl_gen_string(hand, (const unsigned char *)str, strlen(str));
}
/*
* libxl__json_object helper functions
*/
static libxl__json_object *json_object_alloc(libxl__gc *gc,
libxl__json_node_type type)
{
libxl__json_object *obj;
obj = calloc(1, sizeof (libxl__json_object));
if (obj == NULL) {
LIBXL__LOG_ERRNO(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"Failed to allocate a libxl__json_object");
return NULL;
}
obj->type = type;
if (type == JSON_MAP || type == JSON_ARRAY) {
flexarray_t *array = flexarray_make(1, 1);
if (array == NULL) {
LIBXL__LOG_ERRNO(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"Failed to allocate a flexarray");
free(obj);
return NULL;
}
if (type == JSON_MAP)
obj->u.map = array;
else
obj->u.array = array;
}
return obj;
}
static int json_object_append_to(libxl__gc *gc,
libxl__json_object *obj,
libxl__json_object *dst)
{
assert(dst != NULL);
switch (dst->type) {
case JSON_MAP: {
libxl__json_map_node *last;
if (dst->u.map->count == 0) {
LIBXL__LOG(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"Try to add a value to an empty map (with no key)");
return -1;
}
flexarray_get(dst->u.map, dst->u.map->count - 1, (void**)&last);
last->obj = obj;
break;
}
case JSON_ARRAY:
if (flexarray_append(dst->u.array, obj) == 2) {
LIBXL__LOG_ERRNO(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"Failed to grow a flexarray");
return -1;
}
break;
default:
LIBXL__LOG(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"Try append an object is not a map/array (%i)\n",
dst->type);
return -1;
}
obj->parent = dst;
return 0;
}
void libxl__json_object_free(libxl__gc *gc, libxl__json_object *obj)
{
int index = 0;
if (obj == NULL)
return;
switch (obj->type) {
case JSON_STRING:
free(obj->u.string);
break;
case JSON_MAP: {
libxl__json_map_node *node = NULL;
for (index = 0; index < obj->u.map->count; index++) {
if (flexarray_get(obj->u.map, index, (void**)&node) != 0)
break;
libxl__json_object_free(gc, node->obj);
free(node->map_key);
free(node);
node = NULL;
}
flexarray_free(obj->u.map);
break;
}
case JSON_ARRAY: {
libxl__json_object *node = NULL;
break;
for (index = 0; index < obj->u.array->count; index++) {
if (flexarray_get(obj->u.array, index, (void**)&node) != 0)
break;
libxl__json_object_free(gc, node);
node = NULL;
}
flexarray_free(obj->u.array);
break;
}
default:
break;
}
free(obj);
}
libxl__json_object *libxl__json_array_get(const libxl__json_object *o, int i)
{
flexarray_t *array = NULL;
libxl__json_object *obj = NULL;
if ((array = libxl__json_object_get_array(o)) == NULL) {
return NULL;
}
if (i >= array->count)
return NULL;
if (flexarray_get(array, i, (void**)&obj) != 0)
return NULL;
return obj;
}
libxl__json_map_node *libxl__json_map_node_get(const libxl__json_object *o,
int i)
{
flexarray_t *array = NULL;
libxl__json_map_node *obj = NULL;
if ((array = libxl__json_object_get_map(o)) == NULL) {
return NULL;
}
if (i >= array->count)
return NULL;
if (flexarray_get(array, i, (void**)&obj) != 0)
return NULL;
return obj;
}
const libxl__json_object *libxl__json_map_get(const char *key,
const libxl__json_object *o,
libxl__json_node_type expected_type)
{
flexarray_t *maps = NULL;
int index = 0;
if (libxl__json_object_is_map(o)) {
libxl__json_map_node *node = NULL;
maps = o->u.map;
for (index = 0; index < maps->count; index++) {
if (flexarray_get(maps, index, (void**)&node) != 0)
return NULL;
if (strcmp(key, node->map_key) == 0) {
if (expected_type == JSON_ANY
|| (node->obj && node->obj->type == expected_type)) {
return node->obj;
} else {
return NULL;
}
}
}
}
return NULL;
}
/*
* JSON callbacks
*/
static int json_callback_null(void *opaque)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj;
DEBUG_GEN(ctx, null);
if ((obj = json_object_alloc(ctx->gc, JSON_NULL)) == NULL)
return 0;
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
return 1;
}
static int json_callback_boolean(void *opaque, int boolean)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj;
DEBUG_GEN_VALUE(ctx, bool, boolean);
if ((obj = json_object_alloc(ctx->gc,
boolean ? JSON_TRUE : JSON_FALSE)) == NULL)
return 0;
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
return 1;
}
static int json_callback_integer(void *opaque, long value)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj;
DEBUG_GEN_VALUE(ctx, integer, value);
if ((obj = json_object_alloc(ctx->gc, JSON_INTEGER)) == NULL)
return 0;
obj->u.i = value;
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
return 1;
}
static int json_callback_double(void *opaque, double value)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj;
DEBUG_GEN_VALUE(ctx, double, value);
if ((obj = json_object_alloc(ctx->gc, JSON_DOUBLE)) == NULL)
return 0;
obj->u.d = value;
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
return 1;
}
static int json_callback_string(void *opaque, const unsigned char *str,
unsigned int len)
{
libxl__yajl_ctx *ctx = opaque;
char *t = NULL;
libxl__json_object *obj = NULL;
t = malloc(len + 1);
if (t == NULL) {
LIBXL__LOG_ERRNO(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"Failed to allocate");
return 0;
}
DEBUG_GEN_STRING(ctx, str, len);
strncpy(t, (const char *) str, len);
t[len] = 0;
if ((obj = json_object_alloc(ctx->gc, JSON_STRING)) == NULL) {
free(t);
return 0;
}
obj->u.string = t;
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
return 1;
}
static int json_callback_map_key(void *opaque, const unsigned char *str,
unsigned int len)
{
libxl__yajl_ctx *ctx = opaque;
char *t = NULL;
libxl__json_object *obj = ctx->current;
t = malloc(len + 1);
if (t == NULL) {
LIBXL__LOG_ERRNO(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"Failed to allocate");
return 0;
}
DEBUG_GEN_STRING(ctx, str, len);
strncpy(t, (const char *) str, len);
t[len] = 0;
if (libxl__json_object_is_map(obj)) {
libxl__json_map_node *node = malloc(sizeof (libxl__json_map_node));
if (node == NULL) {
LIBXL__LOG_ERRNO(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"Failed to allocate");
return 0;
}
node->map_key = t;
node->obj = NULL;
if (flexarray_append(obj->u.map, node) == 2) {
LIBXL__LOG_ERRNO(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"Failed to grow a flexarray");
return 0;
}
} else {
LIBXL__LOG(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"Current json object is not a map");
return 0;
}
return 1;
}
static int json_callback_start_map(void *opaque)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj = NULL;
DEBUG_GEN(ctx, map_open);
if ((obj = json_object_alloc(ctx->gc, JSON_MAP)) == NULL)
return 0;
if (ctx->current) {
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
}
ctx->current = obj;
if (ctx->head == NULL) {
ctx->head = obj;
}
return 1;
}
static int json_callback_end_map(void *opaque)
{
libxl__yajl_ctx *ctx = opaque;
DEBUG_GEN(ctx, map_close);
if (ctx->current) {
ctx->current = ctx->current->parent;
} else {
LIBXL__LOG(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"No current libxl__json_object, cannot use his parent.");
return 0;
}
return 1;
}
static int json_callback_start_array(void *opaque)
{
libxl__yajl_ctx *ctx = opaque;
libxl__json_object *obj = NULL;
DEBUG_GEN(ctx, array_open);
if ((obj = json_object_alloc(ctx->gc, JSON_ARRAY)) == NULL)
return 0;
if (ctx->current) {
if (json_object_append_to(ctx->gc, obj, ctx->current) == -1) {
libxl__json_object_free(ctx->gc, obj);
return 0;
}
}
ctx->current = obj;
if (ctx->head == NULL) {
ctx->head = obj;
}
return 1;
}
static int json_callback_end_array(void *opaque)
{
libxl__yajl_ctx *ctx = opaque;
DEBUG_GEN(ctx, array_close);
if (ctx->current) {
ctx->current = ctx->current->parent;
} else {
LIBXL__LOG(libxl__gc_owner(ctx->gc), LIBXL__LOG_ERROR,
"No current libxl__json_object, cannot use his parent.");
return 0;
}
return 1;
}
static yajl_callbacks callbacks = {
json_callback_null,
json_callback_boolean,
json_callback_integer,
json_callback_double,
NULL,
json_callback_string,
json_callback_start_map,
json_callback_map_key,
json_callback_end_map,
json_callback_start_array,
json_callback_end_array
};
static void yajl_ctx_free(libxl__yajl_ctx *yajl_ctx)
{
if (yajl_ctx->hand) {
yajl_free(yajl_ctx->hand);
yajl_ctx->hand = NULL;
}
DEBUG_GEN_FREE(yajl_ctx);
}
libxl__json_object *libxl__json_parse(libxl__gc *gc, const char *s)
{
yajl_status status;
libxl__yajl_ctx yajl_ctx;
memset(&yajl_ctx, 0, sizeof (yajl_ctx));
yajl_ctx.gc = gc;
DEBUG_GEN_ALLOC(&yajl_ctx);
if (yajl_ctx.hand == NULL) {
yajl_parser_config cfg = {
.allowComments = 1,
.checkUTF8 = 1,
};
yajl_ctx.hand = yajl_alloc(&callbacks, &cfg, NULL, &yajl_ctx);
}
status = yajl_parse(yajl_ctx.hand, (const unsigned char *)s, strlen(s));
status = yajl_parse_complete(yajl_ctx.hand);
if (status == yajl_status_ok) {
libxl__json_object *o = yajl_ctx.head;
DEBUG_GEN_REPORT(&yajl_ctx);
yajl_ctx.head = NULL;
yajl_ctx_free(&yajl_ctx);
return o;
} else {
unsigned char *str = yajl_get_error(yajl_ctx.hand, 1,
(const unsigned char *)s,
strlen(s));
LIBXL__LOG(libxl__gc_owner(gc), LIBXL__LOG_ERROR,
"yajl error: %s", str);
yajl_free_error(yajl_ctx.hand, str);
libxl__json_object_free(gc, yajl_ctx.head);
yajl_ctx_free(&yajl_ctx);
return NULL;
}
}
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