Andi Kleen | 867a979 | 2016-09-15 15:24:38 -0700 | [diff] [blame] | 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 | |
| 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 | |
Namhyung Kim | bb963e1 | 2017-02-17 17:17:38 +0900 | [diff] [blame] | 52 | if (fd < 0 && verbose > 0 && fn) { |
Andi Kleen | 867a979 | 2016-09-15 15:24:38 -0700 | [diff] [blame] | 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 | |
| 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 | */ |
| 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 | |
| 115 | void free_json(char *map, size_t size, jsmntok_t *tokens) |
| 116 | { |
| 117 | free(tokens); |
| 118 | unmapfile(map, size); |
| 119 | } |
| 120 | |
| 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 */ |
| 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 */ |
| 147 | const char *json_name(jsmntok_t *t) |
| 148 | { |
| 149 | return LOOKUP(jsmn_types, t->type); |
| 150 | } |
| 151 | |
| 152 | int json_len(jsmntok_t *t) |
| 153 | { |
| 154 | return t->end - t->start; |
| 155 | } |
| 156 | |
| 157 | /* Is string t equal to 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 | } |