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 <stdlib.h>
  21 #include <stddef.h>
  22 #include <unistd.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <ctype.h>
  26
  27 #include "device-nodes.h"
  28 #include "libudev.h"
  29 #include "libudev-private.h"
  30 #include "utf8.h"
  31 #include "MurmurHash2.h"
  32
  33 /**
  34  * SECTION:libudev-util
  35  * @short_description: utils
  36  *
  37  * Utilities useful when dealing with devices and device node names.
  38  */
  39
  40 /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
  41 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
  42                                char *result, size_t maxsize, int read_value)
  43 {
  44         char temp[UTIL_PATH_SIZE];
  45         char *subsys;
  46         char *sysname;
  47         struct udev_device *dev;
  48         char *attr;
  49
  50         if (string[0] != '[')
  51                 return -1;
  52
  53         strscpy(temp, sizeof(temp), string);
  54
  55         subsys = &temp[1];
  56
  57         sysname = strchr(subsys, '/');
  58         if (sysname == NULL)
  59                 return -1;
  60         sysname[0] = '\0';
  61         sysname = &sysname[1];
  62
  63         attr = strchr(sysname, ']');
  64         if (attr == NULL)
  65                 return -1;
  66         attr[0] = '\0';
  67         attr = &attr[1];
  68         if (attr[0] == '/')
  69                 attr = &attr[1];
  70         if (attr[0] == '\0')
  71                 attr = NULL;
  72
  73         if (read_value && attr == NULL)
  74                 return -1;
  75
  76         dev = udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
  77         if (dev == NULL)
  78                 return -1;
  79
  80         if (read_value) {
  81                 const char *val;
  82
  83                 val = udev_device_get_sysattr_value(dev, attr);
  84                 if (val != NULL)
  85                         strscpy(result, maxsize, val);
  86                 else
  87                         result[0] = '\0';
  88                 log_debug("value '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
  89         } else {
  90                 size_t l;
  91                 char *s;
  92
  93                 s = result;
  94                 l = strpcpyl(&s, maxsize, udev_device_get_syspath(dev), NULL);
  95                 if (attr != NULL)
  96                         strpcpyl(&s, l, "/", attr, NULL);
  97                 log_debug("path '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
  98         }
  99         udev_device_unref(dev);
 100         return 0;
 101 }
 102
 103 ssize_t util_get_sys_core_link_value(struct udev *udev, const char *slink, const char *syspath, char *value, size_t size)
 104 {
 105         char path[UTIL_PATH_SIZE];
 106         char target[UTIL_PATH_SIZE];
 107         ssize_t len;
 108         const char *pos;
 109
 110         strscpyl(path, sizeof(path), syspath, "/", slink, NULL);
 111         len = readlink(path, target, sizeof(target));
 112         if (len <= 0 || len == (ssize_t)sizeof(target))
 113                 return -1;
 114         target[len] = '\0';
 115         pos = strrchr(target, '/');
 116         if (pos == NULL)
 117                 return -1;
 118         pos = &pos[1];
 119         return strscpy(value, size, pos);
 120 }
 121
 122 int util_resolve_sys_link(struct udev *udev, char *syspath, size_t size)
 123 {
 124         char link_target[UTIL_PATH_SIZE];
 125
 126         ssize_t len;
 127         int i;
 128         int back;
 129         char *base = NULL;
 130
 131         len = readlink(syspath, link_target, sizeof(link_target));
 132         if (len <= 0 || len == (ssize_t)sizeof(link_target))
 133                 return -1;
 134         link_target[len] = '\0';
 135
 136         for (back = 0; startswith(&link_target[back * 3], "../"); back++)
 137                 ;
 138         for (i = 0; i <= back; i++) {
 139                 base = strrchr(syspath, '/');
 140                 if (base == NULL)
 141                         return -EINVAL;
 142                 base[0] = '\0';
 143         }
 144
 145         strscpyl(base, size - (base - syspath), "/", &link_target[back * 3], NULL);
 146         return 0;
 147 }
 148
 149 int util_log_priority(const char *priority)
 150 {
 151         char *endptr;
 152         int prio;
 153
 154         prio = strtoul(priority, &endptr, 10);
 155         if (endptr[0] == '\0' || isspace(endptr[0])) {
 156                 if (prio >= 0 && prio <= 7)
 157                         return prio;
 158                 else
 159                         return -ERANGE;
 160         }
 161
 162         return log_level_from_string(priority);
 163 }
 164
 165 size_t util_path_encode(const char *src, char *dest, size_t size)
 166 {
 167         size_t i, j;
 168
 169         for (i = 0, j = 0; src[i] != '\0'; i++) {
 170                 if (src[i] == '/') {
 171                         if (j+4 >= size) {
 172                                 j = 0;
 173                                 break;
 174                         }
 175                         memcpy(&dest[j], "\\x2f", 4);
 176                         j += 4;
 177                 } else if (src[i] == '\\') {
 178                         if (j+4 >= size) {
 179                                 j = 0;
 180                                 break;
 181                         }
 182                         memcpy(&dest[j], "\\x5c", 4);
 183                         j += 4;
 184                 } else {
 185                         if (j+1 >= size) {
 186                                 j = 0;
 187                                 break;
 188                         }
 189                         dest[j] = src[i];
 190                         j++;
 191                 }
 192         }
 193         dest[j] = '\0';
 194         return j;
 195 }
 196
 197 void util_remove_trailing_chars(char *path, char c)
 198 {
 199         size_t len;
 200
 201         if (path == NULL)
 202                 return;
 203         len = strlen(path);
 204         while (len > 0 && path[len-1] == c)
 205                 path[--len] = '\0';
 206 }
 207
 208 int util_replace_whitespace(const char *str, char *to, size_t len)
 209 {
 210         size_t i, j;
 211
 212         /* strip trailing whitespace */
 213         len = strnlen(str, len);
 214         while (len && isspace(str[len-1]))
 215                 len--;
 216
 217         /* strip leading whitespace */
 218         i = 0;
 219         while ((i < len) && isspace(str[i]))
 220                 i++;
 221
 222         j = 0;
 223         while (i < len) {
 224                 /* substitute multiple whitespace with a single '_' */
 225                 if (isspace(str[i])) {
 226                         while (isspace(str[i]))
 227                                 i++;
 228                         to[j++] = '_';
 229                 }
 230                 to[j++] = str[i++];
 231         }
 232         to[j] = '\0';
 233         return 0;
 234 }
 235
 236 /* allow chars in whitelist, plain ascii, hex-escaping and valid utf8 */
 237 int util_replace_chars(char *str, const char *white)
 238 {
 239         size_t i = 0;
 240         int replaced = 0;
 241
 242         while (str[i] != '\0') {
 243                 int len;
 244
 245                 if (whitelisted_char_for_devnode(str[i], white)) {
 246                         i++;
 247                         continue;
 248                 }
 249
 250                 /* accept hex encoding */
 251                 if (str[i] == '\\' && str[i+1] == 'x') {
 252                         i += 2;
 253                         continue;
 254                 }
 255
 256                 /* accept valid utf8 */
 257                 len = utf8_encoded_valid_unichar(&str[i]);
 258                 if (len > 1) {
 259                         i += len;
 260                         continue;
 261                 }
 262
 263                 /* if space is allowed, replace whitespace with ordinary space */
 264                 if (isspace(str[i]) && white != NULL && strchr(white, ' ') != NULL) {
 265                         str[i] = ' ';
 266                         i++;
 267                         replaced++;
 268                         continue;
 269                 }
 270
 271                 /* everything else is replaced with '_' */
 272                 str[i] = '_';
 273                 i++;
 274                 replaced++;
 275         }
 276         return replaced;
 277 }
 278
 279 /**
 280  * udev_util_encode_string:
 281  * @str: input string to be encoded
 282  * @str_enc: output string to store the encoded input string
 283  * @len: maximum size of the output string, which may be
 284  *       four times as long as the input string
 285  *
 286  * Encode all potentially unsafe characters of a string to the
 287  * corresponding 2 char hex value prefixed by '\x'.
 288  *
 289  * Returns: 0 if the entire string was copied, non-zero otherwise.
 290  **/
 291 _public_ int udev_util_encode_string(const char *str, char *str_enc, size_t len)
 292 {
 293         return encode_devnode_name(str, str_enc, len);
 294 }
 295
 296 unsigned int util_string_hash32(const char *str)
 297 {
 298         return MurmurHash2(str, strlen(str), 0);
 299 }
 300
 301 /* get a bunch of bit numbers out of the hash, and set the bits in our bit field */
 302 uint64_t util_string_bloom64(const char *str)
 303 {
 304         uint64_t bits = 0;
 305         unsigned int hash = util_string_hash32(str);
 306
 307         bits |= 1LLU << (hash & 63);
 308         bits |= 1LLU << ((hash >> 6) & 63);
 309         bits |= 1LLU << ((hash >> 12) & 63);
 310         bits |= 1LLU << ((hash >> 18) & 63);
 311         return bits;
 312 }