udev/udev_sysfs.c

   1 /*
   2  * Copyright (C) 2005-2006 Kay Sievers <kay.sievers@vrfy.org>
   3  *
   4  *      This program is free software; you can redistribute it and/or modify it
   5  *      under the terms of the GNU General Public License as published by the
   6  *      Free Software Foundation version 2 of the License.
   7  *
   8  *      This program is distributed in the hope that it will be useful, but
   9  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  *      General Public License for more details.
  12  *
  13  *      You should have received a copy of the GNU General Public License along
  14  *      with this program; if not, write to the Free Software Foundation, Inc.,
  15  *      51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  16  *
  17  */
  18
  19
  20 #include <stdlib.h>
  21 #include <stdio.h>
  22 #include <stddef.h>
  23 #include <unistd.h>
  24 #include <string.h>
  25 #include <fcntl.h>
  26 #include <ctype.h>
  27 #include <errno.h>
  28 #include <sys/stat.h>
  29
  30 #include "udev.h"
  31
  32 /* device cache */
  33 static LIST_HEAD(dev_list);
  34
  35 /* attribute value cache */
  36 static LIST_HEAD(attr_list);
  37
  38 struct sysfs_attr {
  39         struct list_head node;
  40         char path[PATH_SIZE];
  41         char *value;                    /* points to value_local if value is cached */
  42         char value_local[NAME_SIZE];
  43 };
  44
  45 int sysfs_init(void)
  46 {
  47         INIT_LIST_HEAD(&dev_list);
  48         INIT_LIST_HEAD(&attr_list);
  49         return 0;
  50 }
  51
  52 void sysfs_cleanup(void)
  53 {
  54         struct sysfs_attr *attr_loop;
  55         struct sysfs_attr *attr_temp;
  56         struct sysfs_device *dev_loop;
  57         struct sysfs_device *dev_temp;
  58
  59         list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) {
  60                 list_del(&attr_loop->node);
  61                 free(attr_loop);
  62         }
  63
  64         list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) {
  65                 list_del(&dev_loop->node);
  66                 free(dev_loop);
  67         }
  68 }
  69
  70 void sysfs_device_set_values(struct udev *udev,
  71                              struct sysfs_device *dev, const char *devpath,
  72                              const char *subsystem, const char *driver)
  73 {
  74         char *pos;
  75
  76         strlcpy(dev->devpath, devpath, sizeof(dev->devpath));
  77         if (subsystem != NULL)
  78                 strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem));
  79         if (driver != NULL)
  80                 strlcpy(dev->driver, driver, sizeof(dev->driver));
  81
  82         /* set kernel name */
  83         pos = strrchr(dev->devpath, '/');
  84         if (pos == NULL)
  85                 return;
  86         strlcpy(dev->kernel, &pos[1], sizeof(dev->kernel));
  87         dbg(udev, "kernel='%s'\n", dev->kernel);
  88
  89         /* some devices have '!' in their name, change that to '/' */
  90         pos = dev->kernel;
  91         while (pos[0] != '\0') {
  92                 if (pos[0] == '!')
  93                         pos[0] = '/';
  94                 pos++;
  95         }
  96
  97         /* get kernel number */
  98         pos = &dev->kernel[strlen(dev->kernel)];
  99         while (isdigit(pos[-1]))
 100                 pos--;
 101         strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number));
 102         dbg(udev, "kernel_number='%s'\n", dev->kernel_number);
 103 }
 104
 105 int sysfs_resolve_link(struct udev *udev, char *devpath, size_t size)
 106 {
 107         char link_path[PATH_SIZE];
 108         char link_target[PATH_SIZE];
 109         int len;
 110         int i;
 111         int back;
 112
 113         strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
 114         strlcat(link_path, devpath, sizeof(link_path));
 115         len = readlink(link_path, link_target, sizeof(link_target));
 116         if (len <= 0)
 117                 return -1;
 118         link_target[len] = '\0';
 119         dbg(udev, "path link '%s' points to '%s'\n", devpath, link_target);
 120
 121         for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
 122                 ;
 123         dbg(udev, "base '%s', tail '%s', back %i\n", devpath, &link_target[back * 3], back);
 124         for (i = 0; i <= back; i++) {
 125                 char *pos = strrchr(devpath, '/');
 126
 127                 if (pos == NULL)
 128                         return -1;
 129                 pos[0] = '\0';
 130         }
 131         dbg(udev, "after moving back '%s'\n", devpath);
 132         strlcat(devpath, "/", size);
 133         strlcat(devpath, &link_target[back * 3], size);
 134         return 0;
 135 }
 136
 137 struct sysfs_device *sysfs_device_get(struct udev *udev, const char *devpath)
 138 {
 139         char path[PATH_SIZE];
 140         char devpath_real[PATH_SIZE];
 141         struct sysfs_device *dev;
 142         struct sysfs_device *dev_loop;
 143         struct stat statbuf;
 144         char link_path[PATH_SIZE];
 145         char link_target[PATH_SIZE];
 146         int len;
 147         char *pos;
 148
 149         /* we handle only these devpathes */
 150         if (devpath != NULL &&
 151             strncmp(devpath, "/devices/", 9) != 0 &&
 152             strncmp(devpath, "/subsystem/", 11) != 0 &&
 153             strncmp(devpath, "/module/", 8) != 0 &&
 154             strncmp(devpath, "/bus/", 5) != 0 &&
 155             strncmp(devpath, "/class/", 7) != 0 &&
 156             strncmp(devpath, "/block/", 7) != 0)
 157                 return NULL;
 158
 159         dbg(udev, "open '%s'\n", devpath);
 160         strlcpy(devpath_real, devpath, sizeof(devpath_real));
 161         remove_trailing_chars(devpath_real, '/');
 162         if (devpath[0] == '\0' )
 163                 return NULL;
 164
 165         /* look for device already in cache (we never put an untranslated path in the cache) */
 166         list_for_each_entry(dev_loop, &dev_list, node) {
 167                 if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 168                         dbg(udev, "found in cache '%s'\n", dev_loop->devpath);
 169                         return dev_loop;
 170                 }
 171         }
 172
 173         /* if we got a link, resolve it to the real device */
 174         strlcpy(path, udev_get_sys_path(udev), sizeof(path));
 175         strlcat(path, devpath_real, sizeof(path));
 176         if (lstat(path, &statbuf) != 0) {
 177                 dbg(udev, "stat '%s' failed: %s\n", path, strerror(errno));
 178                 return NULL;
 179         }
 180         if (S_ISLNK(statbuf.st_mode)) {
 181                 if (sysfs_resolve_link(udev, devpath_real, sizeof(devpath_real)) != 0)
 182                         return NULL;
 183
 184                 /* now look for device in cache after path translation */
 185                 list_for_each_entry(dev_loop, &dev_list, node) {
 186                         if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 187                                 dbg(udev, "found in cache '%s'\n", dev_loop->devpath);
 188                                 return dev_loop;
 189                         }
 190                 }
 191         }
 192
 193         /* it is a new device */
 194         dbg(udev, "new uncached device '%s'\n", devpath_real);
 195         dev = malloc(sizeof(struct sysfs_device));
 196         if (dev == NULL)
 197                 return NULL;
 198         memset(dev, 0x00, sizeof(struct sysfs_device));
 199
 200         sysfs_device_set_values(udev, dev, devpath_real, NULL, NULL);
 201
 202         /* get subsystem name */
 203         strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
 204         strlcat(link_path, dev->devpath, sizeof(link_path));
 205         strlcat(link_path, "/subsystem", sizeof(link_path));
 206         len = readlink(link_path, link_target, sizeof(link_target));
 207         if (len > 0) {
 208                 /* get subsystem from "subsystem" link */
 209                 link_target[len] = '\0';
 210                 dbg(udev, "subsystem link '%s' points to '%s'\n", link_path, link_target);
 211                 pos = strrchr(link_target, '/');
 212                 if (pos != NULL)
 213                         strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
 214         } else if (strstr(dev->devpath, "/drivers/") != NULL) {
 215                 strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 216         } else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 217                 strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 218         } else if (strncmp(dev->devpath, "/subsystem/", 11) == 0) {
 219                 pos = strrchr(dev->devpath, '/');
 220                 if (pos == &dev->devpath[10])
 221                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 222         } else if (strncmp(dev->devpath, "/class/", 7) == 0) {
 223                 pos = strrchr(dev->devpath, '/');
 224                 if (pos == &dev->devpath[6])
 225                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 226         } else if (strncmp(dev->devpath, "/bus/", 5) == 0) {
 227                 pos = strrchr(dev->devpath, '/');
 228                 if (pos == &dev->devpath[4])
 229                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 230         }
 231
 232         /* get driver name */
 233         strlcpy(link_path, udev_get_sys_path(udev), sizeof(link_path));
 234         strlcat(link_path, dev->devpath, sizeof(link_path));
 235         strlcat(link_path, "/driver", sizeof(link_path));
 236         len = readlink(link_path, link_target, sizeof(link_target));
 237         if (len > 0) {
 238                 link_target[len] = '\0';
 239                 dbg(udev, "driver link '%s' points to '%s'\n", link_path, link_target);
 240                 pos = strrchr(link_target, '/');
 241                 if (pos != NULL)
 242                         strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
 243         }
 244
 245         dbg(udev, "add to cache 'devpath=%s', subsystem='%s', driver='%s'\n", dev->devpath, dev->subsystem, dev->driver);
 246         list_add(&dev->node, &dev_list);
 247
 248         return dev;
 249 }
 250
 251 struct sysfs_device *sysfs_device_get_parent(struct udev *udev, struct sysfs_device *dev)
 252 {
 253         char parent_devpath[PATH_SIZE];
 254         char *pos;
 255
 256         dbg(udev, "open '%s'\n", dev->devpath);
 257
 258         /* look if we already know the parent */
 259         if (dev->parent != NULL)
 260                 return dev->parent;
 261
 262         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 263         dbg(udev, "'%s'\n", parent_devpath);
 264
 265         /* strip last element */
 266         pos = strrchr(parent_devpath, '/');
 267         if (pos == NULL || pos == parent_devpath)
 268                 return NULL;
 269         pos[0] = '\0';
 270
 271         if (strncmp(parent_devpath, "/class", 6) == 0) {
 272                 pos = strrchr(parent_devpath, '/');
 273                 if (pos == &parent_devpath[6] || pos == parent_devpath) {
 274                         dbg(udev, "/class top level, look for device link\n");
 275                         goto device_link;
 276                 }
 277         }
 278         if (strcmp(parent_devpath, "/block") == 0) {
 279                 dbg(udev, "/block top level, look for device link\n");
 280                 goto device_link;
 281         }
 282
 283         /* are we at the top level? */
 284         pos = strrchr(parent_devpath, '/');
 285         if (pos == NULL || pos == parent_devpath)
 286                 return NULL;
 287
 288         /* get parent and remember it */
 289         dev->parent = sysfs_device_get(udev, parent_devpath);
 290         return dev->parent;
 291
 292 device_link:
 293         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 294         strlcat(parent_devpath, "/device", sizeof(parent_devpath));
 295         if (sysfs_resolve_link(udev, parent_devpath, sizeof(parent_devpath)) != 0)
 296                 return NULL;
 297
 298         /* get parent and remember it */
 299         dev->parent = sysfs_device_get(udev, parent_devpath);
 300         return dev->parent;
 301 }
 302
 303 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct udev *udev, struct sysfs_device *dev, const char *subsystem)
 304 {
 305         struct sysfs_device *dev_parent;
 306
 307         dev_parent = sysfs_device_get_parent(udev, dev);
 308         while (dev_parent != NULL) {
 309                 if (strcmp(dev_parent->subsystem, subsystem) == 0)
 310                         return dev_parent;
 311                 dev_parent = sysfs_device_get_parent(udev, dev_parent);
 312         }
 313         return NULL;
 314 }
 315
 316 char *sysfs_attr_get_value(struct udev *udev, const char *devpath, const char *attr_name)
 317 {
 318         char path_full[PATH_SIZE];
 319         const char *path;
 320         char value[NAME_SIZE];
 321         struct sysfs_attr *attr_loop;
 322         struct sysfs_attr *attr;
 323         struct stat statbuf;
 324         int fd;
 325         ssize_t size;
 326         size_t sysfs_len;
 327
 328         dbg(udev, "open '%s'/'%s'\n", devpath, attr_name);
 329         sysfs_len = strlcpy(path_full, udev_get_sys_path(udev), sizeof(path_full));
 330         if(sysfs_len >= sizeof(path_full))
 331                 sysfs_len = sizeof(path_full) - 1;
 332         path = &path_full[sysfs_len];
 333         strlcat(path_full, devpath, sizeof(path_full));
 334         strlcat(path_full, "/", sizeof(path_full));
 335         strlcat(path_full, attr_name, sizeof(path_full));
 336
 337         /* look for attribute in cache */
 338         list_for_each_entry(attr_loop, &attr_list, node) {
 339                 if (strcmp(attr_loop->path, path) == 0) {
 340                         dbg(udev, "found in cache '%s'\n", attr_loop->path);
 341                         return attr_loop->value;
 342                 }
 343         }
 344
 345         /* store attribute in cache (also negatives are kept in cache) */
 346         dbg(udev, "new uncached attribute '%s'\n", path_full);
 347         attr = malloc(sizeof(struct sysfs_attr));
 348         if (attr == NULL)
 349                 return NULL;
 350         memset(attr, 0x00, sizeof(struct sysfs_attr));
 351         strlcpy(attr->path, path, sizeof(attr->path));
 352         dbg(udev, "add to cache '%s'\n", path_full);
 353         list_add(&attr->node, &attr_list);
 354
 355         if (lstat(path_full, &statbuf) != 0) {
 356                 dbg(udev, "stat '%s' failed: %s\n", path_full, strerror(errno));
 357                 goto out;
 358         }
 359
 360         if (S_ISLNK(statbuf.st_mode)) {
 361                 /* links return the last element of the target path */
 362                 char link_target[PATH_SIZE];
 363                 int len;
 364                 const char *pos;
 365
 366                 len = readlink(path_full, link_target, sizeof(link_target));
 367                 if (len > 0) {
 368                         link_target[len] = '\0';
 369                         pos = strrchr(link_target, '/');
 370                         if (pos != NULL) {
 371                                 dbg(udev, "cache '%s' with link value '%s'\n", path_full, value);
 372                                 strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
 373                                 attr->value = attr->value_local;
 374                         }
 375                 }
 376                 goto out;
 377         }
 378
 379         /* skip directories */
 380         if (S_ISDIR(statbuf.st_mode))
 381                 goto out;
 382
 383         /* skip non-readable files */
 384         if ((statbuf.st_mode & S_IRUSR) == 0)
 385                 goto out;
 386
 387         /* read attribute value */
 388         fd = open(path_full, O_RDONLY);
 389         if (fd < 0) {
 390                 dbg(udev, "attribute '%s' can not be opened\n", path_full);
 391                 goto out;
 392         }
 393         size = read(fd, value, sizeof(value));
 394         close(fd);
 395         if (size < 0)
 396                 goto out;
 397         if (size == sizeof(value))
 398                 goto out;
 399
 400         /* got a valid value, store and return it */
 401         value[size] = '\0';
 402         remove_trailing_chars(value, '\n');
 403         dbg(udev, "cache '%s' with attribute value '%s'\n", path_full, value);
 404         strlcpy(attr->value_local, value, sizeof(attr->value_local));
 405         attr->value = attr->value_local;
 406
 407 out:
 408         return attr->value;
 409 }
 410
 411 int sysfs_lookup_devpath_by_subsys_id(struct udev *udev, char *devpath_full, size_t len, const char *subsystem, const char *id)
 412 {
 413         size_t sysfs_len;
 414         char path_full[PATH_SIZE];
 415         char *path;
 416         struct stat statbuf;
 417
 418         sysfs_len = strlcpy(path_full, udev_get_sys_path(udev), sizeof(path_full));
 419         path = &path_full[sysfs_len];
 420
 421         if (strcmp(subsystem, "subsystem") == 0) {
 422                 strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 423                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 424                 if (stat(path_full, &statbuf) == 0)
 425                         goto found;
 426
 427                 strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 428                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 429                 if (stat(path_full, &statbuf) == 0)
 430                         goto found;
 431                 goto out;
 432
 433                 strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 434                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 435                 if (stat(path_full, &statbuf) == 0)
 436                         goto found;
 437         }
 438
 439         if (strcmp(subsystem, "module") == 0) {
 440                 strlcpy(path, "/module/", sizeof(path_full) - sysfs_len);
 441                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 442                 if (stat(path_full, &statbuf) == 0)
 443                         goto found;
 444                 goto out;
 445         }
 446
 447         if (strcmp(subsystem, "drivers") == 0) {
 448                 char subsys[NAME_SIZE];
 449                 char *driver;
 450
 451                 strlcpy(subsys, id, sizeof(subsys));
 452                 driver = strchr(subsys, ':');
 453                 if (driver != NULL) {
 454                         driver[0] = '\0';
 455                         driver = &driver[1];
 456                         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 457                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 458                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 459                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 460                         if (stat(path_full, &statbuf) == 0)
 461                                 goto found;
 462
 463                         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 464                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 465                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 466                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 467                         if (stat(path_full, &statbuf) == 0)
 468                                 goto found;
 469                 }
 470                 goto out;
 471         }
 472
 473         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 474         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 475         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 476         strlcat(path, id, sizeof(path_full) - sysfs_len);
 477         if (stat(path_full, &statbuf) == 0)
 478                 goto found;
 479
 480         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 481         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 482         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 483         strlcat(path, id, sizeof(path_full) - sysfs_len);
 484         if (stat(path_full, &statbuf) == 0)
 485                 goto found;
 486
 487         strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 488         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 489         strlcat(path, "/", sizeof(path_full) - sysfs_len);
 490         strlcat(path, id, sizeof(path_full) - sysfs_len);
 491         if (stat(path_full, &statbuf) == 0)
 492                 goto found;
 493 out:
 494         return 0;
 495 found:
 496         if (S_ISLNK(statbuf.st_mode))
 497                 sysfs_resolve_link(udev, path, sizeof(path_full) - sysfs_len);
 498         strlcpy(devpath_full, path, len);
 499         return 1;
 500 }