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
mapfile(const char * fn,size_t * size)46 static 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;
70 out:
71 close(fd);
72 return map;
73 }
74
unmapfile(char * map,size_t size)75 static 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 */
parse_json(const char * fn,char ** map,size_t * size,int * len)85 jsmntok_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;
110 error_free:
111 free(tokens);
112 error:
113 unmapfile(*map, *size);
114 return NULL;
115 }
116
free_json(char * map,size_t size,jsmntok_t * tokens)117 void free_json(char *map, size_t size, jsmntok_t *tokens)
118 {
119 free(tokens);
120 unmapfile(map, size);
121 }
122
countchar(char * map,char c,int end)123 static 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 */
json_line(char * map,jsmntok_t * t)134 int json_line(char *map, jsmntok_t *t)
135 {
136 return countchar(map, '\n', t->start) + 1;
137 }
138
139 static 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 */
json_name(jsmntok_t * t)149 const char *json_name(jsmntok_t *t)
150 {
151 return LOOKUP(jsmn_types, t->type);
152 }
153
json_len(jsmntok_t * t)154 int json_len(jsmntok_t *t)
155 {
156 return t->end - t->start;
157 }
158
159 /* Is string t equal to s? */
json_streq(char * map,jsmntok_t * t,const char * s)160 int 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