1/* Parse JSON files using the JSMN parser. */
2
3/*
4 * Copyright (c) 2014, Intel Corporation
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
21 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
22 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
28 * OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * $FreeBSD$
31 *
32*/
33
34#include <stdlib.h>
35#include <string.h>
36#include <sys/mman.h>
37#include <sys/stat.h>
38#include <fcntl.h>
39#include <stdio.h>
40#include <errno.h>
41#include <unistd.h>
42#include "jsmn.h"
43#include "json.h"
44
45
46static char *mapfile(const char *fn, size_t *size)
47{
48	unsigned ps = sysconf(_SC_PAGESIZE);
49	struct stat st;
50	char *map = NULL;
51	int err;
52	int fd = open(fn, O_RDONLY);
53
54	if (fd < 0 && verbose > 0 && fn) {
55		pr_err("Error opening events file '%s': %s\n", fn,
56				strerror(errno));
57	}
58
59	if (fd < 0)
60		return NULL;
61	err = fstat(fd, &st);
62	if (err < 0)
63		goto out;
64	*size = st.st_size;
65	map = mmap(NULL,
66		   (st.st_size + ps - 1) & ~(ps - 1),
67		   PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
68	if (map == MAP_FAILED)
69		map = NULL;
70out:
71	close(fd);
72	return map;
73}
74
75static void unmapfile(char *map, size_t size)
76{
77	unsigned ps = sysconf(_SC_PAGESIZE);
78	munmap(map, roundup(size, ps));
79}
80
81/*
82 * Parse json file using jsmn. Return array of tokens,
83 * and mapped file. Caller needs to free array.
84 */
85jsmntok_t *parse_json(const char *fn, char **map, size_t *size, int *len)
86{
87	jsmn_parser parser;
88	jsmntok_t *tokens;
89	jsmnerr_t res;
90	unsigned sz;
91
92	*map = mapfile(fn, size);
93	if (!*map)
94		return NULL;
95	/* Heuristic */
96	sz = *size * 16;
97	tokens = malloc(sz);
98	if (!tokens)
99		goto error;
100	jsmn_init(&parser);
101	res = jsmn_parse(&parser, *map, *size, tokens,
102			 sz / sizeof(jsmntok_t));
103	if (res != JSMN_SUCCESS) {
104		pr_err("%s: json error %s\n", fn, jsmn_strerror(res));
105		goto error_free;
106	}
107	if (len)
108		*len = parser.toknext;
109	return tokens;
110error_free:
111	free(tokens);
112error:
113	unmapfile(*map, *size);
114	return NULL;
115}
116
117void free_json(char *map, size_t size, jsmntok_t *tokens)
118{
119	free(tokens);
120	unmapfile(map, size);
121}
122
123static int countchar(char *map, char c, int end)
124{
125	int i;
126	int count = 0;
127	for (i = 0; i < end; i++)
128		if (map[i] == c)
129			count++;
130	return count;
131}
132
133/* Return line number of a jsmn token */
134int json_line(char *map, jsmntok_t *t)
135{
136	return countchar(map, '\n', t->start) + 1;
137}
138
139static const char * const jsmn_types[] = {
140	[JSMN_PRIMITIVE] = "primitive",
141	[JSMN_ARRAY] = "array",
142	[JSMN_OBJECT] = "object",
143	[JSMN_STRING] = "string"
144};
145
146#define LOOKUP(a, i) ((i) < (sizeof(a)/sizeof(*(a))) ? ((a)[i]) : "?")
147
148/* Return type name of a jsmn token */
149const char *json_name(jsmntok_t *t)
150{
151	return LOOKUP(jsmn_types, t->type);
152}
153
154int json_len(jsmntok_t *t)
155{
156	return t->end - t->start;
157}
158
159/* Is string t equal to s? */
160int json_streq(char *map, jsmntok_t *t, const char *s)
161{
162	unsigned len = json_len(t);
163	return len == strlen(s) && !strncasecmp(map + t->start, s, len);
164}
165