udev/udev_sysfs.c

   1 /*
   2  * Copyright (C) 2005-2008 Kay Sievers <kay.sievers@vrfy.org>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   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  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <stdlib.h>
  19 #include <stdio.h>
  20 #include <stddef.h>
  21 #include <unistd.h>
  22 #include <string.h>
  23 #include <fcntl.h>
  24 #include <ctype.h>
  25 #include <errno.h>
  26 #include <sys/stat.h>
  27
  28 #include "udev.h"
  29
  30 /* device cache */
  31 static LIST_HEAD(dev_list);
  32
  33 /* attribute value cache */
  34 static LIST_HEAD(attr_list);
  35
  36 struct sysfs_attr {
  37         struct list_head node;
  38         char path[UTIL_PATH_SIZE];
  39         char *value;                    /* points to value_local if value is cached */
  40         char value_local[UTIL_NAME_SIZE];
  41 };
  42
  43 static int resolve_sys_link(struct udev *udev, char *path, size_t size)
  44 {
  45         char link_path[UTIL_PATH_SIZE];
  46         char link_target[UTIL_PATH_SIZE];
  47
  48         int len;
  49         int i;
  50         int back;
  51
  52         util_strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
  53         util_strlcat(link_path, path, sizeof(link_path));
  54         len = readlink(link_path, link_target, sizeof(link_target));
  55         if (len <= 0)
  56                 return -1;
  57         link_target[len] = '\0';
  58         dbg(udev, "path link '%s' points to '%s'\n", path, link_target);
  59
  60         for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
  61                 ;
  62         dbg(udev, "base '%s', tail '%s', back %i\n", path, &link_target[back * 3], back);
  63         for (i = 0; i <= back; i++) {
  64                 char *pos = strrchr(path, '/');
  65
  66                 if (pos == NULL)
  67                         return -1;
  68                 pos[0] = '\0';
  69         }
  70         dbg(udev, "after moving back '%s'\n", path);
  71         util_strlcat(path, "/", size);
  72         util_strlcat(path, &link_target[back * 3], size);
  73         return 0;
  74 }
  75
  76 int sysfs_init(void)
  77 {
  78         INIT_LIST_HEAD(&dev_list);
  79         INIT_LIST_HEAD(&attr_list);
  80         return 0;
  81 }
  82
  83 void sysfs_cleanup(void)
  84 {
  85         struct sysfs_attr *attr_loop;
  86         struct sysfs_attr *attr_temp;
  87         struct sysfs_device *dev_loop;
  88         struct sysfs_device *dev_temp;
  89
  90         list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) {
  91                 list_del(&attr_loop->node);
  92                 free(attr_loop);
  93         }
  94
  95         list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) {
  96                 list_del(&dev_loop->node);
  97                 free(dev_loop);
  98         }
  99 }
 100
 101 void sysfs_device_set_values(struct udev *udev,
 102                              struct sysfs_device *dev, const char *devpath,
 103                              const char *subsystem, const char *driver)
 104 {
 105         char *pos;
 106
 107         util_strlcpy(dev->devpath, devpath, sizeof(dev->devpath));
 108         if (subsystem != NULL)
 109                 util_strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem));
 110         if (driver != NULL)
 111                 util_strlcpy(dev->driver, driver, sizeof(dev->driver));
 112
 113         /* set kernel name */
 114         pos = strrchr(dev->devpath, '/');
 115         if (pos == NULL)
 116                 return;
 117         util_strlcpy(dev->kernel, &pos[1], sizeof(dev->kernel));
 118         dbg(udev, "kernel='%s'\n", dev->kernel);
 119
 120         /* some devices have '!' in their name, change that to '/' */
 121         pos = dev->kernel;
 122         while (pos[0] != '\0') {
 123                 if (pos[0] == '!')
 124                         pos[0] = '/';
 125                 pos++;
 126         }
 127
 128         /* get kernel number */
 129         pos = &dev->kernel[strlen(dev->kernel)];
 130         while (isdigit(pos[-1]))
 131                 pos--;
 132         util_strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number));
 133         dbg(udev, "kernel_number='%s'\n", dev->kernel_number);
 134 }
 135
 136 struct sysfs_device *sysfs_device_get(struct udev *udev, const char *devpath)
 137 {
 138         char path[UTIL_PATH_SIZE];
 139         char devpath_real[UTIL_PATH_SIZE];
 140         struct sysfs_device *dev;
 141         struct sysfs_device *dev_loop;
 142         struct stat statbuf;
 143         char link_path[UTIL_PATH_SIZE];
 144         char link_target[UTIL_PATH_SIZE];
 145         int len;
 146         char *pos;
 147
 148         /* we handle only these devpathes */
 149         if (devpath != NULL &&
 150             strncmp(devpath, "/devices/", 9) != 0 &&
 151             strncmp(devpath, "/subsystem/", 11) != 0 &&
 152             strncmp(devpath, "/module/", 8) != 0 &&
 153             strncmp(devpath, "/bus/", 5) != 0 &&
 154             strncmp(devpath, "/class/", 7) != 0 &&
 155             strncmp(devpath, "/block/", 7) != 0)
 156                 return NULL;
 157
 158         dbg(udev, "open '%s'\n", devpath);
 159         util_strlcpy(devpath_real, devpath, sizeof(devpath_real));
 160         util_remove_trailing_chars(devpath_real, '/');
 161         if (devpath[0] == '\0' )
 162                 return NULL;
 163
 164         /* look for device already in cache (we never put an untranslated path in the cache) */
 165         list_for_each_entry(dev_loop, &dev_list, node) {
 166                 if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 167                         dbg(udev, "found in cache '%s'\n", dev_loop->devpath);
 168                         return dev_loop;
 169                 }
 170         }
 171
 172         /* if we got a link, resolve it to the real device */
 173         util_strlcpy(path, udev_get_sys_path(udev), sizeof(path));
 174         util_strlcat(path, devpath_real, sizeof(path));
 175         if (lstat(path, &statbuf) != 0) {
 176                 dbg(udev, "stat '%s' failed: %m\n", path);
 177                 return NULL;
 178         }
 179         if (S_ISLNK(statbuf.st_mode)) {
 180                 if (resolve_sys_link(udev, devpath_real, sizeof(devpath_real)) != 0)
 181                         return NULL;
 182
 183                 /* now look for device in cache after path translation */
 184                 list_for_each_entry(dev_loop, &dev_list, node) {
 185                         if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 186                                 dbg(udev, "found in cache '%s'\n", dev_loop->devpath);
 187                                 return dev_loop;
 188                         }
 189                 }
 190         }
 191
 192         /* it is a new device */
 193         dbg(udev, "new uncached device '%s'\n", devpath_real);
 194         dev = malloc(sizeof(struct sysfs_device));
 195         if (dev == NULL)
 196                 return NULL;
 197         memset(dev, 0x00, sizeof(struct sysfs_device));
 198
 199         sysfs_device_set_values(udev, dev, devpath_real, NULL, NULL);
 200
 201         /* get subsystem name */
 202         util_strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
 203         util_strlcat(link_path, dev->devpath, sizeof(link_path));
 204         util_strlcat(link_path, "/subsystem", sizeof(link_path));
 205         len = readlink(link_path, link_target, sizeof(link_target));
 206         if (len > 0) {
 207                 /* get subsystem from "subsystem" link */
 208                 link_target[len] = '\0';
 209                 dbg(udev, "subsystem link '%s' points to '%s'\n", link_path, link_target);
 210                 pos = strrchr(link_target, '/');
 211                 if (pos != NULL)
 212                         util_strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
 213         } else if (strstr(dev->devpath, "/drivers/") != NULL) {
 214                 util_strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 215         } else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 216                 util_strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 217         } else if (strncmp(dev->devpath, "/subsystem/", 11) == 0) {
 218                 pos = strrchr(dev->devpath, '/');
 219                 if (pos == &dev->devpath[10])
 220                         util_strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 221         } else if (strncmp(dev->devpath, "/class/", 7) == 0) {
 222                 pos = strrchr(dev->devpath, '/');
 223                 if (pos == &dev->devpath[6])
 224                         util_strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 225         } else if (strncmp(dev->devpath, "/bus/", 5) == 0) {
 226                 pos = strrchr(dev->devpath, '/');
 227                 if (pos == &dev->devpath[4])
 228                         util_strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 229         }
 230
 231         /* get driver name */
 232         util_strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
 233         util_strlcat(link_path, dev->devpath, sizeof(link_path));
 234         util_strlcat(link_path, "/driver", sizeof(link_path));
 235         len = readlink(link_path, link_target, sizeof(link_target));
 236         if (len > 0) {
 237                 link_target[len] = '\0';
 238                 dbg(udev, "driver link '%s' points to '%s'\n", link_path, link_target);
 239                 pos = strrchr(link_target, '/');
 240                 if (pos != NULL)
 241                         util_strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
 242         }
 243
 244         dbg(udev, "add to cache 'devpath=%s', subsystem='%s', driver='%s'\n", dev->devpath, dev->subsystem, dev->driver);
 245         list_add(&dev->node, &dev_list);
 246
 247         return dev;
 248 }
 249
 250 struct sysfs_device *sysfs_device_get_parent(struct udev *udev, struct sysfs_device *dev)
 251 {
 252         char parent_devpath[UTIL_PATH_SIZE];
 253         char *pos;
 254
 255         dbg(udev, "open '%s'\n", dev->devpath);
 256
 257         /* look if we already know the parent */
 258         if (dev->parent != NULL)
 259                 return dev->parent;
 260
 261         util_strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 262         dbg(udev, "'%s'\n", parent_devpath);
 263
 264         /* strip last element */
 265         pos = strrchr(parent_devpath, '/');
 266         if (pos == NULL || pos == parent_devpath)
 267                 return NULL;
 268         pos[0] = '\0';
 269
 270         if (strncmp(parent_devpath, "/class", 6) == 0) {
 271                 pos = strrchr(parent_devpath, '/');
 272                 if (pos == &parent_devpath[6] || pos == parent_devpath) {
 273                         dbg(udev, "/class top level, look for device link\n");
 274                         goto device_link;
 275                 }
 276         }
 277         if (strcmp(parent_devpath, "/block") == 0) {
 278                 dbg(udev, "/block top level, look for device link\n");
 279                 goto device_link;
 280         }
 281
 282         /* are we at the top level? */
 283         pos = strrchr(parent_devpath, '/');
 284         if (pos == NULL || pos == parent_devpath)
 285                 return NULL;
 286
 287         /* get parent and remember it */
 288         dev->parent = sysfs_device_get(udev, parent_devpath);
 289         return dev->parent;
 290
 291 device_link:
 292         util_strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 293         util_strlcat(parent_devpath, "/device", sizeof(parent_devpath));
 294         if (resolve_sys_link(udev, parent_devpath, sizeof(parent_devpath)) != 0)
 295                 return NULL;
 296
 297         /* get parent and remember it */
 298         dev->parent = sysfs_device_get(udev, parent_devpath);
 299         return dev->parent;
 300 }
 301
 302 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct udev *udev, struct sysfs_device *dev, const char *subsystem)
 303 {
 304         struct sysfs_device *dev_parent;
 305
 306         dev_parent = sysfs_device_get_parent(udev, dev);
 307         while (dev_parent != NULL) {
 308                 if (strcmp(dev_parent->subsystem, subsystem) == 0)
 309                         return dev_parent;
 310                 dev_parent = sysfs_device_get_parent(udev, dev_parent);
 311         }
 312         return NULL;
 313 }
 314
 315 char *sysfs_attr_get_value(struct udev *udev, const char *devpath, const char *attr_name)
 316 {
 317         char path_full[UTIL_PATH_SIZE];
 318         const char *path;
 319         char value[UTIL_NAME_SIZE];
 320         struct sysfs_attr *attr_loop;
 321         struct sysfs_attr *attr;
 322         struct stat statbuf;
 323         int fd;
 324         ssize_t size;
 325         size_t sysfs_len;
 326
 327         dbg(udev, "open '%s'/'%s'\n", devpath, attr_name);
 328         sysfs_len = util_strlcpy(path_full, udev_get_sys_path(udev), sizeof(path_full));
 329         if(sysfs_len >= sizeof(path_full))
 330                 sysfs_len = sizeof(path_full) - 1;
 331         path = &path_full[sysfs_len];
 332         util_strlcat(path_full, devpath, sizeof(path_full));
 333         util_strlcat(path_full, "/", sizeof(path_full));
 334         util_strlcat(path_full, attr_name, sizeof(path_full));
 335
 336         /* look for attribute in cache */
 337         list_for_each_entry(attr_loop, &attr_list, node) {
 338                 if (strcmp(attr_loop->path, path) == 0) {
 339                         dbg(udev, "found in cache '%s'\n", attr_loop->path);
 340                         return attr_loop->value;
 341                 }
 342         }
 343
 344         /* store attribute in cache (also negatives are kept in cache) */
 345         dbg(udev, "new uncached attribute '%s'\n", path_full);
 346         attr = malloc(sizeof(struct sysfs_attr));
 347         if (attr == NULL)
 348                 return NULL;
 349         memset(attr, 0x00, sizeof(struct sysfs_attr));
 350         util_strlcpy(attr->path, path, sizeof(attr->path));
 351         dbg(udev, "add to cache '%s'\n", path_full);
 352         list_add(&attr->node, &attr_list);
 353
 354         if (lstat(path_full, &statbuf) != 0) {
 355                 dbg(udev, "stat '%s' failed: %m\n", path_full);
 356                 goto out;
 357         }
 358
 359         if (S_ISLNK(statbuf.st_mode)) {
 360                 /* links return the last element of the target path */
 361                 char link_target[UTIL_PATH_SIZE];
 362                 int len;
 363                 const char *pos;
 364
 365                 len = readlink(path_full, link_target, sizeof(link_target));
 366                 if (len > 0) {
 367                         link_target[len] = '\0';
 368                         pos = strrchr(link_target, '/');
 369                         if (pos != NULL) {
 370                                 dbg(udev, "cache '%s' with link value '%s'\n", path_full, value);
 371                                 util_strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
 372                                 attr->value = attr->value_local;
 373                         }
 374                 }
 375                 goto out;
 376         }
 377
 378         /* skip directories */
 379         if (S_ISDIR(statbuf.st_mode))
 380                 goto out;
 381
 382         /* skip non-readable files */
 383         if ((statbuf.st_mode & S_IRUSR) == 0)
 384                 goto out;
 385
 386         /* read attribute value */
 387         fd = open(path_full, O_RDONLY);
 388         if (fd < 0) {
 389                 dbg(udev, "attribute '%s' can not be opened\n", path_full);
 390                 goto out;
 391         }
 392         size = read(fd, value, sizeof(value));
 393         close(fd);
 394         if (size < 0)
 395                 goto out;
 396         if (size == sizeof(value))
 397                 goto out;
 398
 399         /* got a valid value, store and return it */
 400         value[size] = '\0';
 401         util_remove_trailing_chars(value, '\n');
 402         dbg(udev, "cache '%s' with attribute value '%s'\n", path_full, value);
 403         util_strlcpy(attr->value_local, value, sizeof(attr->value_local));
 404         attr->value = attr->value_local;
 405
 406 out:
 407         return attr->value;
 408 }
 409
 410 int sysfs_lookup_devpath_by_subsys_id(struct udev *udev, char *devpath_full, size_t len, const char *subsystem, const char *id)
 411 {
 412         size_t sysfs_len;
 413         char path_full[UTIL_PATH_SIZE];
 414         char *path;
 415         struct stat statbuf;
 416
 417         sysfs_len = util_strlcpy(path_full, udev_get_sys_path(udev), sizeof(path_full));
 418         path = &path_full[sysfs_len];
 419
 420         if (strcmp(subsystem, "subsystem") == 0) {
 421                 util_strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 422                 util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 423                 if (stat(path_full, &statbuf) == 0)
 424                         goto found;
 425
 426                 util_strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 427                 util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 428                 if (stat(path_full, &statbuf) == 0)
 429                         goto found;
 430                 goto out;
 431
 432                 util_strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 433                 util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 434                 if (stat(path_full, &statbuf) == 0)
 435                         goto found;
 436         }
 437
 438         if (strcmp(subsystem, "module") == 0) {
 439                 util_strlcpy(path, "/module/", sizeof(path_full) - sysfs_len);
 440                 util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 441                 if (stat(path_full, &statbuf) == 0)
 442                         goto found;
 443                 goto out;
 444         }
 445
 446         if (strcmp(subsystem, "drivers") == 0) {
 447                 char subsys[UTIL_NAME_SIZE];
 448                 char *driver;
 449
 450                 util_strlcpy(subsys, id, sizeof(subsys));
 451                 driver = strchr(subsys, ':');
 452                 if (driver != NULL) {
 453                         driver[0] = '\0';
 454                         driver = &driver[1];
 455                         util_strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 456                         util_strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 457                         util_strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 458                         util_strlcat(path, driver, sizeof(path_full) - sysfs_len);
 459                         if (stat(path_full, &statbuf) == 0)
 460                                 goto found;
 461
 462                         util_strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 463                         util_strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 464                         util_strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 465                         util_strlcat(path, driver, sizeof(path_full) - sysfs_len);
 466                         if (stat(path_full, &statbuf) == 0)
 467                                 goto found;
 468                 }
 469                 goto out;
 470         }
 471
 472         util_strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 473         util_strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 474         util_strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 475         util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 476         if (stat(path_full, &statbuf) == 0)
 477                 goto found;
 478
 479         util_strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 480         util_strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 481         util_strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 482         util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 483         if (stat(path_full, &statbuf) == 0)
 484                 goto found;
 485
 486         util_strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 487         util_strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 488         util_strlcat(path, "/", sizeof(path_full) - sysfs_len);
 489         util_strlcat(path, id, sizeof(path_full) - sysfs_len);
 490         if (stat(path_full, &statbuf) == 0)
 491                 goto found;
 492 out:
 493         return 0;
 494 found:
 495         if (S_ISLNK(statbuf.st_mode))
 496                 resolve_sys_link(udev, path, sizeof(path_full) - sysfs_len);
 497         util_strlcpy(devpath_full, path, len);
 498         return 1;
 499 }