src/libudev/libudev-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <stddef.h>
  23 #include <unistd.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include <dirent.h>
  27 #include <ctype.h>
  28 #include <fcntl.h>
  29 #include <time.h>
  30 #include <pwd.h>
  31 #include <grp.h>
  32 #include <sys/stat.h>
  33 #include <sys/param.h>
  34
  35 #include "device-nodes.h"
  36 #include "libudev.h"
  37 #include "libudev-private.h"
  38 #include "utf8.h"
  39 #include "MurmurHash2.h"
  40
  41 /**
  42  * SECTION:libudev-util
  43  * @short_description: utils
  44  *
  45  * Utilities useful when dealing with devices and device node names.
  46  */
  47
  48 /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
  49 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
  50                                char *result, size_t maxsize, int read_value)
  51 {
  52         char temp[UTIL_PATH_SIZE];
  53         char *subsys;
  54         char *sysname;
  55         struct udev_device *dev;
  56         char *attr;
  57
  58         if (string[0] != '[')
  59                 return -1;
  60
  61         strscpy(temp, sizeof(temp), string);
  62
  63         subsys = &temp[1];
  64
  65         sysname = strchr(subsys, '/');
  66         if (sysname == NULL)
  67                 return -1;
  68         sysname[0] = '\0';
  69         sysname = &sysname[1];
  70
  71         attr = strchr(sysname, ']');
  72         if (attr == NULL)
  73                 return -1;
  74         attr[0] = '\0';
  75         attr = &attr[1];
  76         if (attr[0] == '/')
  77                 attr = &attr[1];
  78         if (attr[0] == '\0')
  79                 attr = NULL;
  80
  81         if (read_value && attr == NULL)
  82                 return -1;
  83
  84         dev = udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
  85         if (dev == NULL)
  86                 return -1;
  87
  88         if (read_value) {
  89                 const char *val;
  90
  91                 val = udev_device_get_sysattr_value(dev, attr);
  92                 if (val != NULL)
  93                         strscpy(result, maxsize, val);
  94                 else
  95                         result[0] = '\0';
  96                 udev_dbg(udev, "value '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
  97         } else {
  98                 size_t l;
  99                 char *s;
 100
 101                 s = result;
 102                 l = strpcpyl(&s, maxsize, udev_device_get_syspath(dev), NULL);
 103                 if (attr != NULL)
 104                         strpcpyl(&s, l, "/", attr, NULL);
 105                 udev_dbg(udev, "path '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
 106         }
 107         udev_device_unref(dev);
 108         return 0;
 109 }
 110
 111 ssize_t util_get_sys_core_link_value(struct udev *udev, const char *slink, const char *syspath, char *value, size_t size)
 112 {
 113         char path[UTIL_PATH_SIZE];
 114         char target[UTIL_PATH_SIZE];
 115         ssize_t len;
 116         const char *pos;
 117
 118         strscpyl(path, sizeof(path), syspath, "/", slink, NULL);
 119         len = readlink(path, target, sizeof(target));
 120         if (len <= 0 || len == (ssize_t)sizeof(target))
 121                 return -1;
 122         target[len] = '\0';
 123         pos = strrchr(target, '/');
 124         if (pos == NULL)
 125                 return -1;
 126         pos = &pos[1];
 127         return strscpy(value, size, pos);
 128 }
 129
 130 int util_resolve_sys_link(struct udev *udev, char *syspath, size_t size)
 131 {
 132         char link_target[UTIL_PATH_SIZE];
 133
 134         ssize_t len;
 135         int i;
 136         int back;
 137         char *base = NULL;
 138
 139         len = readlink(syspath, link_target, sizeof(link_target));
 140         if (len <= 0 || len == (ssize_t)sizeof(link_target))
 141                 return -1;
 142         link_target[len] = '\0';
 143
 144         for (back = 0; startswith(&link_target[back * 3], "../"); back++)
 145                 ;
 146         for (i = 0; i <= back; i++) {
 147                 base = strrchr(syspath, '/');
 148                 if (base == NULL)
 149                         return -EINVAL;
 150                 base[0] = '\0';
 151         }
 152
 153         strscpyl(base, size - (base - syspath), "/", &link_target[back * 3], NULL);
 154         return 0;
 155 }
 156
 157 int util_log_priority(const char *priority)
 158 {
 159         char *endptr;
 160         int prio;
 161
 162         prio = strtoul(priority, &endptr, 10);
 163         if (endptr[0] == '\0' || isspace(endptr[0])) {
 164                 if (prio >= 0 && prio <= 7)
 165                         return prio;
 166                 else
 167                         return -ERANGE;
 168         }
 169
 170         return log_level_from_string(priority);
 171 }
 172
 173 size_t util_path_encode(const char *src, char *dest, size_t size)
 174 {
 175         size_t i, j;
 176
 177         for (i = 0, j = 0; src[i] != '\0'; i++) {
 178                 if (src[i] == '/') {
 179                         if (j+4 >= size) {
 180                                 j = 0;
 181                                 break;
 182                         }
 183                         memcpy(&dest[j], "\\x2f", 4);
 184                         j += 4;
 185                 } else if (src[i] == '\\') {
 186                         if (j+4 >= size) {
 187                                 j = 0;
 188                                 break;
 189                         }
 190                         memcpy(&dest[j], "\\x5c", 4);
 191                         j += 4;
 192                 } else {
 193                         if (j+1 >= size) {
 194                                 j = 0;
 195                                 break;
 196                         }
 197                         dest[j] = src[i];
 198                         j++;
 199                 }
 200         }
 201         dest[j] = '\0';
 202         return j;
 203 }
 204
 205 void util_remove_trailing_chars(char *path, char c)
 206 {
 207         size_t len;
 208
 209         if (path == NULL)
 210                 return;
 211         len = strlen(path);
 212         while (len > 0 && path[len-1] == c)
 213                 path[--len] = '\0';
 214 }
 215
 216 int util_replace_whitespace(const char *str, char *to, size_t len)
 217 {
 218         size_t i, j;
 219
 220         /* strip trailing whitespace */
 221         len = strnlen(str, len);
 222         while (len && isspace(str[len-1]))
 223                 len--;
 224
 225         /* strip leading whitespace */
 226         i = 0;
 227         while (isspace(str[i]) && (i < len))
 228                 i++;
 229
 230         j = 0;
 231         while (i < len) {
 232                 /* substitute multiple whitespace with a single '_' */
 233                 if (isspace(str[i])) {
 234                         while (isspace(str[i]))
 235                                 i++;
 236                         to[j++] = '_';
 237                 }
 238                 to[j++] = str[i++];
 239         }
 240         to[j] = '\0';
 241         return 0;
 242 }
 243
 244 /* allow chars in whitelist, plain ascii, hex-escaping and valid utf8 */
 245 int util_replace_chars(char *str, const char *white)
 246 {
 247         size_t i = 0;
 248         int replaced = 0;
 249
 250         while (str[i] != '\0') {
 251                 int len;
 252
 253                 if (whitelisted_char_for_devnode(str[i], white)) {
 254                         i++;
 255                         continue;
 256                 }
 257
 258                 /* accept hex encoding */
 259                 if (str[i] == '\\' && str[i+1] == 'x') {
 260                         i += 2;
 261                         continue;
 262                 }
 263
 264                 /* accept valid utf8 */
 265                 len = utf8_encoded_valid_unichar(&str[i]);
 266                 if (len > 1) {
 267                         i += len;
 268                         continue;
 269                 }
 270
 271                 /* if space is allowed, replace whitespace with ordinary space */
 272                 if (isspace(str[i]) && white != NULL && strchr(white, ' ') != NULL) {
 273                         str[i] = ' ';
 274                         i++;
 275                         replaced++;
 276                         continue;
 277                 }
 278
 279                 /* everything else is replaced with '_' */
 280                 str[i] = '_';
 281                 i++;
 282                 replaced++;
 283         }
 284         return replaced;
 285 }
 286
 287 /**
 288  * udev_util_encode_string:
 289  * @str: input string to be encoded
 290  * @str_enc: output string to store the encoded input string
 291  * @len: maximum size of the output string, which may be
 292  *       four times as long as the input string
 293  *
 294  * Encode all potentially unsafe characters of a string to the
 295  * corresponding 2 char hex value prefixed by '\x'.
 296  *
 297  * Returns: 0 if the entire string was copied, non-zero otherwise.
 298  **/
 299 _public_ int udev_util_encode_string(const char *str, char *str_enc, size_t len)
 300 {
 301         return encode_devnode_name(str, str_enc, len);
 302 }
 303
 304 unsigned int util_string_hash32(const char *str)
 305 {
 306         return MurmurHash2(str, strlen(str), 0);
 307 }
 308
 309 /* get a bunch of bit numbers out of the hash, and set the bits in our bit field */
 310 uint64_t util_string_bloom64(const char *str)
 311 {
 312         uint64_t bits = 0;
 313         unsigned int hash = util_string_hash32(str);
 314
 315         bits |= 1LLU << (hash & 63);
 316         bits |= 1LLU << ((hash >> 6) & 63);
 317         bits |= 1LLU << ((hash >> 12) & 63);
 318         bits |= 1LLU << ((hash >> 18) & 63);
 319         return bits;
 320 }