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