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 int util_delete_path(struct udev *udev, const char *path)
  49 {
  50         char p[UTIL_PATH_SIZE];
  51         char *pos;
  52         int err = 0;
  53
  54         if (path[0] == '/')
  55                 while(path[1] == '/')
  56                         path++;
  57         strscpy(p, sizeof(p), path);
  58         pos = strrchr(p, '/');
  59         if (pos == p || pos == NULL)
  60                 return 0;
  61
  62         for (;;) {
  63                 *pos = '\0';
  64                 pos = strrchr(p, '/');
  65
  66                 /* don't remove the last one */
  67                 if ((pos == p) || (pos == NULL))
  68                         break;
  69
  70                 err = rmdir(p);
  71                 if (err < 0) {
  72                         if (errno == ENOENT)
  73                                 err = 0;
  74                         break;
  75                 }
  76         }
  77         return err;
  78 }
  79
  80 uid_t util_lookup_user(struct udev *udev, const char *user)
  81 {
  82         char *endptr;
  83         struct passwd pwbuf;
  84         struct passwd *pw;
  85         uid_t uid;
  86         size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
  87         char *buf = alloca(buflen);
  88
  89         if (streq(user, "root"))
  90                 return 0;
  91         uid = strtoul(user, &endptr, 10);
  92         if (endptr[0] == '\0')
  93                 return uid;
  94
  95         errno = getpwnam_r(user, &pwbuf, buf, buflen, &pw);
  96         if (pw != NULL)
  97                 return pw->pw_uid;
  98         if (errno == 0 || errno == ENOENT || errno == ESRCH)
  99                 udev_err(udev, "specified user '%s' unknown\n", user);
 100         else
 101                 udev_err(udev, "error resolving user '%s': %m\n", user);
 102         return 0;
 103 }
 104
 105 gid_t util_lookup_group(struct udev *udev, const char *group)
 106 {
 107         char *endptr;
 108         struct group grbuf;
 109         struct group *gr;
 110         gid_t gid = 0;
 111         size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
 112         char *buf = NULL;
 113
 114         if (streq(group, "root"))
 115                 return 0;
 116         gid = strtoul(group, &endptr, 10);
 117         if (endptr[0] == '\0')
 118                 return gid;
 119         gid = 0;
 120         for (;;) {
 121                 char *newbuf;
 122
 123                 newbuf = realloc(buf, buflen);
 124                 if (!newbuf)
 125                         break;
 126                 buf = newbuf;
 127                 errno = getgrnam_r(group, &grbuf, buf, buflen, &gr);
 128                 if (gr != NULL) {
 129                         gid = gr->gr_gid;
 130                 } else if (errno == ERANGE) {
 131                         buflen *= 2;
 132                         continue;
 133                 } else if (errno == 0 || errno == ENOENT || errno == ESRCH) {
 134                         udev_err(udev, "specified group '%s' unknown\n", group);
 135                 } else {
 136                         udev_err(udev, "error resolving group '%s': %m\n", group);
 137                 }
 138                 break;
 139         }
 140         free(buf);
 141         return gid;
 142 }
 143
 144 /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
 145 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
 146                                char *result, size_t maxsize, int read_value)
 147 {
 148         char temp[UTIL_PATH_SIZE];
 149         char *subsys;
 150         char *sysname;
 151         struct udev_device *dev;
 152         char *attr;
 153
 154         if (string[0] != '[')
 155                 return -1;
 156
 157         strscpy(temp, sizeof(temp), string);
 158
 159         subsys = &temp[1];
 160
 161         sysname = strchr(subsys, '/');
 162         if (sysname == NULL)
 163                 return -1;
 164         sysname[0] = '\0';
 165         sysname = &sysname[1];
 166
 167         attr = strchr(sysname, ']');
 168         if (attr == NULL)
 169                 return -1;
 170         attr[0] = '\0';
 171         attr = &attr[1];
 172         if (attr[0] == '/')
 173                 attr = &attr[1];
 174         if (attr[0] == '\0')
 175                 attr = NULL;
 176
 177         if (read_value && attr == NULL)
 178                 return -1;
 179
 180         dev = udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
 181         if (dev == NULL)
 182                 return -1;
 183
 184         if (read_value) {
 185                 const char *val;
 186
 187                 val = udev_device_get_sysattr_value(dev, attr);
 188                 if (val != NULL)
 189                         strscpy(result, maxsize, val);
 190                 else
 191                         result[0] = '\0';
 192                 udev_dbg(udev, "value '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
 193         } else {
 194                 size_t l;
 195                 char *s;
 196
 197                 s = result;
 198                 l = strpcpyl(&s, maxsize, udev_device_get_syspath(dev), NULL);
 199                 if (attr != NULL)
 200                         strpcpyl(&s, l, "/", attr, NULL);
 201                 udev_dbg(udev, "path '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
 202         }
 203         udev_device_unref(dev);
 204         return 0;
 205 }
 206
 207 ssize_t util_get_sys_core_link_value(struct udev *udev, const char *slink, const char *syspath, char *value, size_t size)
 208 {
 209         char path[UTIL_PATH_SIZE];
 210         char target[UTIL_PATH_SIZE];
 211         ssize_t len;
 212         const char *pos;
 213
 214         strscpyl(path, sizeof(path), syspath, "/", slink, NULL);
 215         len = readlink(path, target, sizeof(target));
 216         if (len <= 0 || len == (ssize_t)sizeof(target))
 217                 return -1;
 218         target[len] = '\0';
 219         pos = strrchr(target, '/');
 220         if (pos == NULL)
 221                 return -1;
 222         pos = &pos[1];
 223         return strscpy(value, size, pos);
 224 }
 225
 226 int util_resolve_sys_link(struct udev *udev, char *syspath, size_t size)
 227 {
 228         char link_target[UTIL_PATH_SIZE];
 229
 230         ssize_t len;
 231         int i;
 232         int back;
 233         char *base = NULL;
 234
 235         len = readlink(syspath, link_target, sizeof(link_target));
 236         if (len <= 0 || len == (ssize_t)sizeof(link_target))
 237                 return -1;
 238         link_target[len] = '\0';
 239
 240         for (back = 0; startswith(&link_target[back * 3], "../"); back++)
 241                 ;
 242         for (i = 0; i <= back; i++) {
 243                 base = strrchr(syspath, '/');
 244                 if (base == NULL)
 245                         return -EINVAL;
 246                 base[0] = '\0';
 247         }
 248
 249         strscpyl(base, size - (base - syspath), "/", &link_target[back * 3], NULL);
 250         return 0;
 251 }
 252
 253 int util_log_priority(const char *priority)
 254 {
 255         char *endptr;
 256         int prio;
 257
 258         prio = strtol(priority, &endptr, 10);
 259         if (endptr[0] == '\0' || isspace(endptr[0]))
 260                 return prio;
 261         if (startswith(priority, "err"))
 262                 return LOG_ERR;
 263         if (startswith(priority, "info"))
 264                 return LOG_INFO;
 265         if (startswith(priority, "debug"))
 266                 return LOG_DEBUG;
 267         return 0;
 268 }
 269
 270 size_t util_path_encode(const char *src, char *dest, size_t size)
 271 {
 272         size_t i, j;
 273
 274         for (i = 0, j = 0; src[i] != '\0'; i++) {
 275                 if (src[i] == '/') {
 276                         if (j+4 >= size) {
 277                                 j = 0;
 278                                 break;
 279                         }
 280                         memcpy(&dest[j], "\\x2f", 4);
 281                         j += 4;
 282                 } else if (src[i] == '\\') {
 283                         if (j+4 >= size) {
 284                                 j = 0;
 285                                 break;
 286                         }
 287                         memcpy(&dest[j], "\\x5c", 4);
 288                         j += 4;
 289                 } else {
 290                         if (j+1 >= size) {
 291                                 j = 0;
 292                                 break;
 293                         }
 294                         dest[j] = src[i];
 295                         j++;
 296                 }
 297         }
 298         dest[j] = '\0';
 299         return j;
 300 }
 301
 302 void util_remove_trailing_chars(char *path, char c)
 303 {
 304         size_t len;
 305
 306         if (path == NULL)
 307                 return;
 308         len = strlen(path);
 309         while (len > 0 && path[len-1] == c)
 310                 path[--len] = '\0';
 311 }
 312
 313 int util_replace_whitespace(const char *str, char *to, size_t len)
 314 {
 315         size_t i, j;
 316
 317         /* strip trailing whitespace */
 318         len = strnlen(str, len);
 319         while (len && isspace(str[len-1]))
 320                 len--;
 321
 322         /* strip leading whitespace */
 323         i = 0;
 324         while (isspace(str[i]) && (i < len))
 325                 i++;
 326
 327         j = 0;
 328         while (i < len) {
 329                 /* substitute multiple whitespace with a single '_' */
 330                 if (isspace(str[i])) {
 331                         while (isspace(str[i]))
 332                                 i++;
 333                         to[j++] = '_';
 334                 }
 335                 to[j++] = str[i++];
 336         }
 337         to[j] = '\0';
 338         return 0;
 339 }
 340
 341 /* allow chars in whitelist, plain ascii, hex-escaping and valid utf8 */
 342 int util_replace_chars(char *str, const char *white)
 343 {
 344         size_t i = 0;
 345         int replaced = 0;
 346
 347         while (str[i] != '\0') {
 348                 int len;
 349
 350                 if (whitelisted_char_for_devnode(str[i], white)) {
 351                         i++;
 352                         continue;
 353                 }
 354
 355                 /* accept hex encoding */
 356                 if (str[i] == '\\' && str[i+1] == 'x') {
 357                         i += 2;
 358                         continue;
 359                 }
 360
 361                 /* accept valid utf8 */
 362                 len = utf8_encoded_valid_unichar(&str[i]);
 363                 if (len > 1) {
 364                         i += len;
 365                         continue;
 366                 }
 367
 368                 /* if space is allowed, replace whitespace with ordinary space */
 369                 if (isspace(str[i]) && white != NULL && strchr(white, ' ') != NULL) {
 370                         str[i] = ' ';
 371                         i++;
 372                         replaced++;
 373                         continue;
 374                 }
 375
 376                 /* everything else is replaced with '_' */
 377                 str[i] = '_';
 378                 i++;
 379                 replaced++;
 380         }
 381         return replaced;
 382 }
 383
 384 /**
 385  * udev_util_encode_string:
 386  * @str: input string to be encoded
 387  * @str_enc: output string to store the encoded input string
 388  * @len: maximum size of the output string, which may be
 389  *       four times as long as the input string
 390  *
 391  * Encode all potentially unsafe characters of a string to the
 392  * corresponding 2 char hex value prefixed by '\x'.
 393  *
 394  * Returns: 0 if the entire string was copied, non-zero otherwise.
 395  **/
 396 _public_ int udev_util_encode_string(const char *str, char *str_enc, size_t len)
 397 {
 398         return encode_devnode_name(str, str_enc, len);
 399 }
 400
 401 unsigned int util_string_hash32(const char *str)
 402 {
 403         return MurmurHash2(str, strlen(str), 0);
 404 }
 405
 406 /* get a bunch of bit numbers out of the hash, and set the bits in our bit field */
 407 uint64_t util_string_bloom64(const char *str)
 408 {
 409         uint64_t bits = 0;
 410         unsigned int hash = util_string_hash32(str);
 411
 412         bits |= 1LLU << (hash & 63);
 413         bits |= 1LLU << ((hash >> 6) & 63);
 414         bits |= 1LLU << ((hash >> 12) & 63);
 415         bits |= 1LLU << ((hash >> 18) & 63);
 416         return bits;
 417 }