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/*
* Contributed by Jacob Teplitsky <jacob.teplitsky@ericsson.com>
*
* libcbor is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
/**
* This code demonstrates how cJSON (https://github.com/DaveGamble/cJSON)
* callbacks can be used in conjuction with the streaming parser to translate
* JSON to CBOR. Please note that cbor_builder_* APIs are internal and thus
* subject to change.
*
* The example will only be compiled when cJSON is available
*/
#include <cjson/cJSON.h>
#include <float.h>
#include <math.h>
#include <string.h>
#include "cbor.h"
#include "cbor/internal/builder_callbacks.h"
#include "cbor/internal/loaders.h"
typedef void (*cbor_load_callback_t)(cJSON *, const struct cbor_callbacks *,
void *);
cbor_item_t *cjson_cbor_load(void *source,
cbor_load_callback_t cbor_load_callback) {
static struct cbor_callbacks callbacks = {
.uint64 = &cbor_builder_uint64_callback,
.negint64 = &cbor_builder_negint64_callback,
.string = &cbor_builder_string_callback,
.array_start = &cbor_builder_array_start_callback,
.map_start = &cbor_builder_map_start_callback,
.null = &cbor_builder_null_callback,
.boolean = &cbor_builder_boolean_callback,
.float4 = &cbor_builder_float4_callback,
};
/* Context stack */
struct _cbor_stack stack = _cbor_stack_init();
/* Target for callbacks */
struct _cbor_decoder_context context = (struct _cbor_decoder_context){
.stack = &stack,
};
cbor_load_callback(source, &callbacks, &context);
return context.root;
}
void cjson_cbor_stream_decode(cJSON *source,
const struct cbor_callbacks *callbacks,
void *context) {
switch (source->type) {
case cJSON_False: {
callbacks->boolean(context, false);
return;
}
case cJSON_True: {
callbacks->boolean(context, true);
return;
}
case cJSON_NULL: {
callbacks->null(context);
return;
}
case cJSON_Number: {
// This is stupid -- ints and doubles cannot are not distinguished
if (fabs(source->valuedouble - source->valueint) > DBL_EPSILON) {
callbacks->float4(context, source->valuedouble);
} else {
// XXX: This is not portable
if (source->valueint >= 0) {
callbacks->uint64(context, source->valueint);
} else {
callbacks->negint64(context, source->valueint + 1);
}
}
return;
}
case cJSON_String: {
// XXX: Assume cJSON handled unicode correctly
callbacks->string(context, (unsigned char *)source->valuestring,
strlen(source->valuestring));
return;
}
case cJSON_Array: {
callbacks->array_start(context, cJSON_GetArraySize(source));
cJSON *item = source->child;
while (item != NULL) {
cjson_cbor_stream_decode(item, callbacks, context);
item = item->next;
}
return;
}
case cJSON_Object: {
callbacks->map_start(context, cJSON_GetArraySize(source));
cJSON *item = source->child;
while (item != NULL) {
callbacks->string(context, (unsigned char *)item->string,
strlen(item->string));
cjson_cbor_stream_decode(item, callbacks, context);
item = item->next;
}
return;
}
}
}
void usage() {
printf("Usage: cjson [input JSON file]\n");
exit(1);
}
int main(int argc, char *argv[]) {
if (argc != 2) usage();
FILE *f = fopen(argv[1], "rb");
if (f == NULL) usage();
/* Read input file into a buffer (cJSON doesn't work with streams) */
fseek(f, 0, SEEK_END);
size_t length = (size_t)ftell(f);
fseek(f, 0, SEEK_SET);
char *json_buffer = malloc(length + 1);
fread(json_buffer, length, 1, f);
json_buffer[length] = '\0';
/* Convert between JSON and CBOR */
cJSON *json = cJSON_Parse(json_buffer);
cbor_item_t *cbor = cjson_cbor_load(json, cjson_cbor_stream_decode);
/* Print out CBOR bytes */
unsigned char *buffer;
size_t buffer_size,
cbor_length = cbor_serialize_alloc(cbor, &buffer, &buffer_size);
fwrite(buffer, 1, cbor_length, stdout);
free(buffer);
fflush(stdout);
cJSON_Delete(json);
cbor_decref(&cbor);
}
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