json.cpp

//#include <curl/curl.h>
#include <stdlib.h>

#include "json.h"
#include "log.h"
#include "buf.h"

#define BUFFER_SIZE 32768
#define JSON_TOKENS 256

static size_t fetch_data(void *buffer, size_t size, size_t nmemb, void *userp)
{
	buf_t *buf = (buf_t *)userp;
	size_t total = size * nmemb;

	if (buf->limit - buf->len < total)
	{
		buf = buf_size(buf, buf->limit + total);
		log_null(buf);
	}

	buf_concat(buf, buffer, total);

	return total;
}

char * json_fetch(char *url)
{
	CURL *curl = curl_easy_init();
	log_null(curl);

	curl_easy_setopt(curl, CURLOPT_URL, url);

	buf_t *buf = buf_size(NULL, BUFFER_SIZE);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fetch_data);
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, buf);
	curl_easy_setopt(curl, CURLOPT_USERAGENT, "jsmn-example (https://github.com/alisdair/jsmn-example, alisdair@mcdiarmid.org)");

	struct curl_slist *hs = curl_slist_append(NULL, "Accept: application/json");
	curl_easy_setopt(curl, CURLOPT_HTTPHEADER, hs);

	CURLcode res = curl_easy_perform(curl);
	if (res != CURLE_OK)
		log_die("curl_easy_perform failed: %s", curl_easy_strerror(res));

	curl_easy_cleanup(curl);
	curl_slist_free_all(hs);

	char *js = buf_tostr(buf);
	free(buf->data);
	free(buf);

	return js;
}

jsmntok_t * json_tokenise(char *js)
{
	jsmn_parser parser;
	jsmn_init(&parser);

	unsigned int n = JSON_TOKENS;
	jsmntok_t *tokens = malloc(sizeof(jsmntok_t)* n);
	log_null(tokens);

	int ret = jsmn_parse(&parser, js, tokens, n);

	while (ret == JSMN_ERROR_NOMEM)
	{
		n = n * 2 + 1;
		tokens = realloc(tokens, sizeof(jsmntok_t)* n);
		log_null(tokens);
		ret = jsmn_parse(&parser, js, tokens, n);
	}

	if (ret == JSMN_ERROR_INVAL)
		log_die("jsmn_parse: invalid JSON string");
	if (ret == JSMN_ERROR_PART)
		log_die("jsmn_parse: truncated JSON string");

	return tokens;
}

bool json_token_streq(char *js, jsmntok_t *t, char *s)
{
	return (strncmp(js + t->start, s, t->end - t->start) == 0
		&& strlen(s) == (size_t)(t->end - t->start));
}

char * json_token_tostr(char *js, jsmntok_t *t)
{
	js[t->end] = '\0';
	return js + t->start;
}