util.c

   1 /*
   2  * libuci - Library for the Unified Configuration Interface
   3  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 /*
  16  * This file contains wrappers to standard functions, which
  17  * throw exceptions upon failure.
  18  */
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21 #include <sys/file.h>
  22 #include <stdbool.h>
  23 #include <unistd.h>
  24 #include <ctype.h>
  25 #include <fcntl.h>
  26
  27 #define LINEBUF 32
  28 #define LINEBUF_MAX     4096
  29
  30 static void *uci_malloc(struct uci_context *ctx, size_t size)
  31 {
  32         void *ptr;
  33
  34         ptr = malloc(size);
  35         if (!ptr)
  36                 UCI_THROW(ctx, UCI_ERR_MEM);
  37         memset(ptr, 0, size);
  38
  39         return ptr;
  40 }
  41
  42 static void *uci_realloc(struct uci_context *ctx, void *ptr, size_t size)
  43 {
  44         ptr = realloc(ptr, size);
  45         if (!ptr)
  46                 UCI_THROW(ctx, UCI_ERR_MEM);
  47
  48         return ptr;
  49 }
  50
  51 static char *uci_strdup(struct uci_context *ctx, const char *str)
  52 {
  53         char *ptr;
  54
  55         ptr = strdup(str);
  56         if (!ptr)
  57                 UCI_THROW(ctx, UCI_ERR_MEM);
  58
  59         return ptr;
  60 }
  61
  62 /*
  63  * validate strings for names and types, reject special characters
  64  * for names, only alphanum and _ is allowed (shell compatibility)
  65  * for types, we allow more characters
  66  */
  67 static bool uci_validate_str(const char *str, bool name)
  68 {
  69         if (!*str)
  70                 return false;
  71
  72         while (*str) {
  73                 char c = *str;
  74                 if (!isalnum(c) && c != '_') {
  75                         if (name || (c < 33) || (c > 126))
  76                                 return false;
  77                 }
  78                 str++;
  79         }
  80         return true;
  81 }
  82
  83 static inline bool uci_validate_name(const char *str)
  84 {
  85         return uci_validate_str(str, true);
  86 }
  87
  88 static void uci_alloc_parse_context(struct uci_context *ctx)
  89 {
  90         ctx->pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
  91 }
  92
  93 int uci_parse_tuple(struct uci_context *ctx, char *str, char **package, char **section, char **option, char **value)
  94 {
  95         char *last = NULL;
  96
  97         UCI_HANDLE_ERR(ctx);
  98         UCI_ASSERT(ctx, str && package && section && option);
  99
 100         *package = strtok(str, ".");
 101         if (!*package || !uci_validate_name(*package))
 102                 goto error;
 103
 104         last = *package;
 105         *section = strtok(NULL, ".");
 106         if (!*section)
 107                 goto lastval;
 108
 109         last = *section;
 110         *option = strtok(NULL, ".");
 111         if (!*option)
 112                 goto lastval;
 113
 114         last = *option;
 115
 116 lastval:
 117         last = strchr(last, '=');
 118         if (last) {
 119                 if (!value)
 120                         goto error;
 121
 122                 *last = 0;
 123                 last++;
 124                 if (!*last)
 125                         goto error;
 126                 *value = last;
 127         }
 128
 129         if (*section && !uci_validate_name(*section))
 130                 goto error;
 131         if (*option && !uci_validate_name(*option))
 132                 goto error;
 133
 134         goto done;
 135
 136 error:
 137         UCI_THROW(ctx, UCI_ERR_PARSE);
 138
 139 done:
 140         return 0;
 141 }
 142
 143
 144 static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
 145 {
 146         struct uci_parse_context *pctx = ctx->pctx;
 147
 148         pctx->reason = reason;
 149         pctx->byte = pos - pctx->buf;
 150         UCI_THROW(ctx, UCI_ERR_PARSE);
 151 }
 152
 153
 154 /*
 155  * Fetch a new line from the input stream and resize buffer if necessary
 156  */
 157 static void uci_getln(struct uci_context *ctx, int offset)
 158 {
 159         struct uci_parse_context *pctx = ctx->pctx;
 160         char *p;
 161         int ofs;
 162
 163         if (pctx->buf == NULL) {
 164                 pctx->buf = uci_malloc(ctx, LINEBUF);
 165                 pctx->bufsz = LINEBUF;
 166         }
 167
 168         ofs = offset;
 169         do {
 170                 p = &pctx->buf[ofs];
 171                 p[ofs] = 0;
 172
 173                 p = fgets(p, pctx->bufsz - ofs, pctx->file);
 174                 if (!p || !*p)
 175                         return;
 176
 177                 ofs += strlen(p);
 178                 if (pctx->buf[ofs - 1] == '\n') {
 179                         pctx->line++;
 180                         pctx->buf[ofs - 1] = 0;
 181                         return;
 182                 }
 183
 184                 if (pctx->bufsz > LINEBUF_MAX/2)
 185                         uci_parse_error(ctx, p, "line too long");
 186
 187                 pctx->bufsz *= 2;
 188                 pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
 189         } while (1);
 190 }
 191
 192 /*
 193  * open a stream and go to the right position
 194  *
 195  * note: when opening for write and seeking to the beginning of
 196  * the stream, truncate the file
 197  */
 198 static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
 199 {
 200         struct stat statbuf;
 201         FILE *file = NULL;
 202         int fd, ret;
 203         int mode = (write ? O_RDWR : O_RDONLY);
 204
 205         if (create)
 206                 mode |= O_CREAT;
 207
 208         if (!write && ((stat(filename, &statbuf) < 0) ||
 209                 ((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
 210                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 211         }
 212
 213         fd = open(filename, mode, UCI_FILEMODE);
 214         if (fd <= 0)
 215                 goto error;
 216
 217         if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
 218                 goto error;
 219
 220         ret = lseek(fd, 0, pos);
 221
 222         if (ret < 0)
 223                 goto error;
 224
 225         file = fdopen(fd, (write ? "w+" : "r"));
 226         if (file)
 227                 goto done;
 228
 229 error:
 230         UCI_THROW(ctx, UCI_ERR_IO);
 231 done:
 232         return file;
 233 }
 234
 235 static void uci_close_stream(FILE *stream)
 236 {
 237         int fd;
 238
 239         if (!stream)
 240                 return;
 241
 242         fd = fileno(stream);
 243         flock(fd, LOCK_UN);
 244         fclose(stream);
 245 }
 246
 247