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
31 #include <stdlib.h>
32 #include <string.h>
33 #include <sys/mman.h>
34 #include <sys/stat.h>
35 #include <fcntl.h>
36 #include <stdio.h>
37 #include <errno.h>
38 #include <unistd.h>
39 #include "jsmn.h"
40 #include "json.h"
41 #include <linux/kernel.h>
42
43
mapfile(const char * fn,size_t * size)44 static char *mapfile(const char *fn, size_t *size)
45 {
46 unsigned ps = sysconf(_SC_PAGESIZE);
47 struct stat st;
48 char *map = NULL;
49 int err;
50 int fd = open(fn, O_RDONLY);
51
52 if (fd < 0 && verbose > 0 && fn) {
53 pr_err("Error opening events file '%s': %s\n", fn,
54 strerror(errno));
55 }
56
57 if (fd < 0)
58 return NULL;
59 err = fstat(fd, &st);
60 if (err < 0)
61 goto out;
62 *size = st.st_size;
63 map = mmap(NULL,
64 (st.st_size + ps - 1) & ~(ps - 1),
65 PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
66 if (map == MAP_FAILED)
67 map = NULL;
68 out:
69 close(fd);
70 return map;
71 }
72
unmapfile(char * map,size_t size)73 static void unmapfile(char *map, size_t size)
74 {
75 unsigned ps = sysconf(_SC_PAGESIZE);
76 munmap(map, roundup(size, ps));
77 }
78
79 /*
80 * Parse json file using jsmn. Return array of tokens,
81 * and mapped file. Caller needs to free array.
82 */
parse_json(const char * fn,char ** map,size_t * size,int * len)83 jsmntok_t *parse_json(const char *fn, char **map, size_t *size, int *len)
84 {
85 jsmn_parser parser;
86 jsmntok_t *tokens;
87 jsmnerr_t res;
88 unsigned sz;
89
90 *map = mapfile(fn, size);
91 if (!*map)
92 return NULL;
93 /* Heuristic */
94 sz = *size * 16;
95 tokens = malloc(sz);
96 if (!tokens)
97 goto error;
98 jsmn_init(&parser);
99 res = jsmn_parse(&parser, *map, *size, tokens,
100 sz / sizeof(jsmntok_t));
101 if (res != JSMN_SUCCESS) {
102 pr_err("%s: json error %s\n", fn, jsmn_strerror(res));
103 goto error_free;
104 }
105 if (len)
106 *len = parser.toknext;
107 return tokens;
108 error_free:
109 free(tokens);
110 error:
111 unmapfile(*map, *size);
112 return NULL;
113 }
114
free_json(char * map,size_t size,jsmntok_t * tokens)115 void free_json(char *map, size_t size, jsmntok_t *tokens)
116 {
117 free(tokens);
118 unmapfile(map, size);
119 }
120
countchar(char * map,char c,int end)121 static int countchar(char *map, char c, int end)
122 {
123 int i;
124 int count = 0;
125 for (i = 0; i < end; i++)
126 if (map[i] == c)
127 count++;
128 return count;
129 }
130
131 /* Return line number of a jsmn token */
json_line(char * map,jsmntok_t * t)132 int json_line(char *map, jsmntok_t *t)
133 {
134 return countchar(map, '\n', t->start) + 1;
135 }
136
137 static const char * const jsmn_types[] = {
138 [JSMN_PRIMITIVE] = "primitive",
139 [JSMN_ARRAY] = "array",
140 [JSMN_OBJECT] = "object",
141 [JSMN_STRING] = "string"
142 };
143
144 #define LOOKUP(a, i) ((i) < (sizeof(a)/sizeof(*(a))) ? ((a)[i]) : "?")
145
146 /* Return type name of a jsmn token */
json_name(jsmntok_t * t)147 const char *json_name(jsmntok_t *t)
148 {
149 return LOOKUP(jsmn_types, t->type);
150 }
151
json_len(jsmntok_t * t)152 int json_len(jsmntok_t *t)
153 {
154 return t->end - t->start;
155 }
156
157 /* Is string t equal to s? */
json_streq(char * map,jsmntok_t * t,const char * s)158 int json_streq(char *map, jsmntok_t *t, const char *s)
159 {
160 unsigned len = json_len(t);
161 return len == strlen(s) && !strncasecmp(map + t->start, s, len);
162 }
163