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 <fcntl.h>
  25 #include <ctype.h>
  26 #include <errno.h>
  27 #include <sys/stat.h>
  28
  29 #include "udev.h"
  30
  31 char sysfs_path[PATH_SIZE];
  32
  33 /* device cache */
  34 static LIST_HEAD(dev_list);
  35
  36 /* attribute value cache */
  37 static LIST_HEAD(attr_list);
  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         const char *env;
  48
  49         env = getenv("SYSFS_PATH");
  50         if (env) {
  51                 strlcpy(sysfs_path, env, sizeof(sysfs_path));
  52                 remove_trailing_chars(sysfs_path, '/');
  53         } else
  54                 strlcpy(sysfs_path, "/sys", sizeof(sysfs_path));
  55         dbg("sysfs_path='%s'", sysfs_path);
  56
  57         INIT_LIST_HEAD(&dev_list);
  58         INIT_LIST_HEAD(&attr_list);
  59         return 0;
  60 }
  61
  62 void sysfs_cleanup(void)
  63 {
  64         struct sysfs_attr *attr_loop;
  65         struct sysfs_attr *attr_temp;
  66         struct sysfs_device *dev_loop;
  67         struct sysfs_device *dev_temp;
  68
  69         list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) {
  70                 list_del(&attr_loop->node);
  71                 free(attr_loop);
  72         }
  73
  74         list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) {
  75                 list_del(&dev_loop->node);
  76                 free(dev_loop);
  77         }
  78 }
  79
  80 void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath,
  81                              const char *subsystem, const char *driver)
  82 {
  83         char *pos;
  84
  85         strlcpy(dev->devpath, devpath, sizeof(dev->devpath));
  86         if (subsystem != NULL)
  87                 strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem));
  88         if (driver != NULL)
  89                 strlcpy(dev->driver, driver, sizeof(dev->driver));
  90
  91         /* set kernel name */
  92         pos = strrchr(dev->devpath, '/');
  93         if (pos == NULL)
  94                 return;
  95         strlcpy(dev->kernel, &pos[1], sizeof(dev->kernel));
  96         dbg("kernel='%s'", dev->kernel);
  97
  98         /* some devices have '!' in their name, change that to '/' */
  99         pos = dev->kernel;
 100         while (pos[0] != '\0') {
 101                 if (pos[0] == '!')
 102                         pos[0] = '/';
 103                 pos++;
 104         }
 105
 106         /* get kernel number */
 107         pos = &dev->kernel[strlen(dev->kernel)];
 108         while (isdigit(pos[-1]))
 109                 pos--;
 110         strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number));
 111         dbg("kernel_number='%s'", dev->kernel_number);
 112 }
 113
 114 int sysfs_resolve_link(char *devpath, size_t size)
 115 {
 116         char link_path[PATH_SIZE];
 117         char link_target[PATH_SIZE];
 118         int len;
 119         int i;
 120         int back;
 121
 122         strlcpy(link_path, sysfs_path, sizeof(link_path));
 123         strlcat(link_path, devpath, sizeof(link_path));
 124         len = readlink(link_path, link_target, sizeof(link_target));
 125         if (len <= 0)
 126                 return -1;
 127         link_target[len] = '\0';
 128         dbg("path link '%s' points to '%s'", devpath, link_target);
 129
 130         for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
 131                 ;
 132         dbg("base '%s', tail '%s', back %i", devpath, &link_target[back * 3], back);
 133         for (i = 0; i <= back; i++) {
 134                 char *pos = strrchr(devpath, '/');
 135
 136                 if (pos == NULL)
 137                         return -1;
 138                 pos[0] = '\0';
 139         }
 140         dbg("after moving back '%s'", devpath);
 141         strlcat(devpath, "/", size);
 142         strlcat(devpath, &link_target[back * 3], size);
 143         return 0;
 144 }
 145
 146 struct sysfs_device *sysfs_device_get(const char *devpath)
 147 {
 148         char path[PATH_SIZE];
 149         char devpath_real[PATH_SIZE];
 150         struct sysfs_device *dev;
 151         struct sysfs_device *dev_loop;
 152         struct stat statbuf;
 153         char link_path[PATH_SIZE];
 154         char link_target[PATH_SIZE];
 155         int len;
 156         char *pos;
 157
 158         /* we handle only these devpathes */
 159         if (devpath != NULL &&
 160             strncmp(devpath, "/devices/", 9) != 0 &&
 161             strncmp(devpath, "/subsystem/", 11) != 0 &&
 162             strncmp(devpath, "/module/", 8) != 0 &&
 163             strncmp(devpath, "/bus/", 5) != 0 &&
 164             strncmp(devpath, "/class/", 7) != 0 &&
 165             strncmp(devpath, "/block/", 7) != 0)
 166                 return NULL;
 167
 168         dbg("open '%s'", devpath);
 169         strlcpy(devpath_real, devpath, sizeof(devpath_real));
 170         remove_trailing_chars(devpath_real, '/');
 171         if (devpath[0] == '\0' )
 172                 return NULL;
 173
 174         /* look for device already in cache (we never put an untranslated path in the cache) */
 175         list_for_each_entry(dev_loop, &dev_list, node) {
 176                 if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 177                         dbg("found in cache '%s'", dev_loop->devpath);
 178                         return dev_loop;
 179                 }
 180         }
 181
 182         /* if we got a link, resolve it to the real device */
 183         strlcpy(path, sysfs_path, sizeof(path));
 184         strlcat(path, devpath_real, sizeof(path));
 185         if (lstat(path, &statbuf) != 0) {
 186                 dbg("stat '%s' failed: %s", path, strerror(errno));
 187                 return NULL;
 188         }
 189         if (S_ISLNK(statbuf.st_mode)) {
 190                 if (sysfs_resolve_link(devpath_real, sizeof(devpath_real)) != 0)
 191                         return NULL;
 192
 193                 /* now look for device in cache after path translation */
 194                 list_for_each_entry(dev_loop, &dev_list, node) {
 195                         if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 196                                 dbg("found in cache '%s'", dev_loop->devpath);
 197                                 return dev_loop;
 198                         }
 199                 }
 200         }
 201
 202         /* it is a new device */
 203         dbg("new uncached device '%s'", devpath_real);
 204         dev = malloc(sizeof(struct sysfs_device));
 205         if (dev == NULL)
 206                 return NULL;
 207         memset(dev, 0x00, sizeof(struct sysfs_device));
 208
 209         sysfs_device_set_values(dev, devpath_real, NULL, NULL);
 210
 211         /* get subsystem name */
 212         strlcpy(link_path, sysfs_path, sizeof(link_path));
 213         strlcat(link_path, dev->devpath, sizeof(link_path));
 214         strlcat(link_path, "/subsystem", sizeof(link_path));
 215         len = readlink(link_path, link_target, sizeof(link_target));
 216         if (len > 0) {
 217                 /* get subsystem from "subsystem" link */
 218                 link_target[len] = '\0';
 219                 dbg("subsystem link '%s' points to '%s'", link_path, link_target);
 220                 pos = strrchr(link_target, '/');
 221                 if (pos != NULL)
 222                         strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
 223         } else if (strncmp(dev->devpath, "/class/", 7) == 0) {
 224                 /* get subsystem from class dir */
 225                 strlcpy(dev->subsystem, &dev->devpath[7], sizeof(dev->subsystem));
 226                 pos = strchr(dev->subsystem, '/');
 227                 if (pos != NULL)
 228                         pos[0] = '\0';
 229                 else
 230                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 231         } else if (strncmp(dev->devpath, "/block/", 7) == 0) {
 232                 strlcpy(dev->subsystem, "block", sizeof(dev->subsystem));
 233         } else if (strncmp(dev->devpath, "/devices/", 9) == 0) {
 234                 /* get subsystem from "bus" link */
 235                 strlcpy(link_path, sysfs_path, sizeof(link_path));
 236                 strlcat(link_path, dev->devpath, sizeof(link_path));
 237                 strlcat(link_path, "/bus", sizeof(link_path));
 238                 len = readlink(link_path, link_target, sizeof(link_target));
 239                 if (len > 0) {
 240                         link_target[len] = '\0';
 241                         dbg("bus link '%s' points to '%s'", link_path, link_target);
 242                         pos = strrchr(link_target, '/');
 243                         if (pos != NULL)
 244                                 strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
 245                 }
 246         } else if (strstr(dev->devpath, "/drivers/") != NULL) {
 247                 strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 248         } else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 249                 strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 250         } else if (strncmp(dev->devpath, "/subsystem/", 11) == 0) {
 251                 pos = strrchr(dev->devpath, '/');
 252                 if (pos == &dev->devpath[10])
 253                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 254         } else if (strncmp(dev->devpath, "/bus/", 5) == 0) {
 255                 pos = strrchr(dev->devpath, '/');
 256                 if (pos == &dev->devpath[4])
 257                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 258         }
 259
 260         /* get driver name */
 261         strlcpy(link_path, sysfs_path, sizeof(link_path));
 262         strlcat(link_path, dev->devpath, sizeof(link_path));
 263         strlcat(link_path, "/driver", sizeof(link_path));
 264         len = readlink(link_path, link_target, sizeof(link_target));
 265         if (len > 0) {
 266                 link_target[len] = '\0';
 267                 dbg("driver link '%s' points to '%s'", link_path, link_target);
 268                 pos = strrchr(link_target, '/');
 269                 if (pos != NULL)
 270                         strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
 271         }
 272
 273         dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'", dev->devpath, dev->subsystem, dev->driver);
 274         list_add(&dev->node, &dev_list);
 275
 276         return dev;
 277 }
 278
 279 struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 280 {
 281         char parent_devpath[PATH_SIZE];
 282         char *pos;
 283
 284         dbg("open '%s'", dev->devpath);
 285
 286         /* look if we already know the parent */
 287         if (dev->parent != NULL)
 288                 return dev->parent;
 289
 290         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 291         dbg("'%s'", parent_devpath);
 292
 293         /* strip last element */
 294         pos = strrchr(parent_devpath, '/');
 295         if (pos == NULL || pos == parent_devpath)
 296                 return NULL;
 297         pos[0] = '\0';
 298
 299         if (strncmp(parent_devpath, "/class", 6) == 0) {
 300                 pos = strrchr(parent_devpath, '/');
 301                 if (pos == &parent_devpath[6] || pos == parent_devpath) {
 302                         dbg("/class top level, look for device link");
 303                         goto device_link;
 304                 }
 305         }
 306         if (strcmp(parent_devpath, "/block") == 0) {
 307                 dbg("/block top level, look for device link");
 308                 goto device_link;
 309         }
 310
 311         /* are we at the top level? */
 312         pos = strrchr(parent_devpath, '/');
 313         if (pos == NULL || pos == parent_devpath)
 314                 return NULL;
 315
 316         /* get parent and remember it */
 317         dev->parent = sysfs_device_get(parent_devpath);
 318         return dev->parent;
 319
 320 device_link:
 321         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 322         strlcat(parent_devpath, "/device", sizeof(parent_devpath));
 323         if (sysfs_resolve_link(parent_devpath, sizeof(parent_devpath)) != 0)
 324                 return NULL;
 325
 326         /* get parent and remember it */
 327         dev->parent = sysfs_device_get(parent_devpath);
 328         return dev->parent;
 329 }
 330
 331 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct sysfs_device *dev, const char *subsystem)
 332 {
 333         struct sysfs_device *dev_parent;
 334
 335         dev_parent = sysfs_device_get_parent(dev);
 336         while (dev_parent != NULL) {
 337                 if (strcmp(dev_parent->subsystem, subsystem) == 0)
 338                         return dev_parent;
 339                 dev_parent = sysfs_device_get_parent(dev_parent);
 340         }
 341         return NULL;
 342 }
 343
 344 char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 345 {
 346         char path_full[PATH_SIZE];
 347         const char *path;
 348         char value[NAME_SIZE];
 349         struct sysfs_attr *attr_loop;
 350         struct sysfs_attr *attr;
 351         struct stat statbuf;
 352         int fd;
 353         ssize_t size;
 354         size_t sysfs_len;
 355
 356         dbg("open '%s'/'%s'", devpath, attr_name);
 357         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 358         if(sysfs_len >= sizeof(path_full))
 359                 sysfs_len = sizeof(path_full) - 1;
 360         path = &path_full[sysfs_len];
 361         strlcat(path_full, devpath, sizeof(path_full));
 362         strlcat(path_full, "/", sizeof(path_full));
 363         strlcat(path_full, attr_name, sizeof(path_full));
 364
 365         /* look for attribute in cache */
 366         list_for_each_entry(attr_loop, &attr_list, node) {
 367                 if (strcmp(attr_loop->path, path) == 0) {
 368                         dbg("found in cache '%s'", attr_loop->path);
 369                         return attr_loop->value;
 370                 }
 371         }
 372
 373         /* store attribute in cache (also negatives are kept in cache) */
 374         dbg("new uncached attribute '%s'", path_full);
 375         attr = malloc(sizeof(struct sysfs_attr));
 376         if (attr == NULL)
 377                 return NULL;
 378         memset(attr, 0x00, sizeof(struct sysfs_attr));
 379         strlcpy(attr->path, path, sizeof(attr->path));
 380         dbg("add to cache '%s'", path_full);
 381         list_add(&attr->node, &attr_list);
 382
 383         if (lstat(path_full, &statbuf) != 0) {
 384                 dbg("stat '%s' failed: %s", path_full, strerror(errno));
 385                 goto out;
 386         }
 387
 388         if (S_ISLNK(statbuf.st_mode)) {
 389                 /* links return the last element of the target path */
 390                 char link_target[PATH_SIZE];
 391                 int len;
 392                 const char *pos;
 393
 394                 len = readlink(path_full, link_target, sizeof(link_target));
 395                 if (len > 0) {
 396                         link_target[len] = '\0';
 397                         pos = strrchr(link_target, '/');
 398                         if (pos != NULL) {
 399                                 dbg("cache '%s' with link value '%s'", path_full, value);
 400                                 strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
 401                                 attr->value = attr->value_local;
 402                         }
 403                 }
 404                 goto out;
 405         }
 406
 407         /* skip directories */
 408         if (S_ISDIR(statbuf.st_mode))
 409                 goto out;
 410
 411         /* skip non-readable files */
 412         if ((statbuf.st_mode & S_IRUSR) == 0)
 413                 goto out;
 414
 415         /* read attribute value */
 416         fd = open(path_full, O_RDONLY);
 417         if (fd < 0) {
 418                 dbg("attribute '%s' can not be opened", path_full);
 419                 goto out;
 420         }
 421         size = read(fd, value, sizeof(value));
 422         close(fd);
 423         if (size < 0)
 424                 goto out;
 425         if (size == sizeof(value))
 426                 goto out;
 427
 428         /* got a valid value, store and return it */
 429         value[size] = '\0';
 430         remove_trailing_chars(value, '\n');
 431         dbg("cache '%s' with attribute value '%s'", path_full, value);
 432         strlcpy(attr->value_local, value, sizeof(attr->value_local));
 433         attr->value = attr->value_local;
 434
 435 out:
 436         return attr->value;
 437 }
 438
 439 int sysfs_lookup_devpath_by_subsys_id(char *devpath_full, size_t len, const char *subsystem, const char *id)
 440 {
 441         size_t sysfs_len;
 442         char path_full[PATH_SIZE];
 443         char *path;
 444         struct stat statbuf;
 445
 446         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 447         path = &path_full[sysfs_len];
 448
 449         if (strcmp(subsystem, "subsystem") == 0) {
 450                 strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 451                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 452                 if (stat(path_full, &statbuf) == 0)
 453                         goto found;
 454
 455                 strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 456                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 457                 if (stat(path_full, &statbuf) == 0)
 458                         goto found;
 459                 goto out;
 460
 461                 strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 462                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 463                 if (stat(path_full, &statbuf) == 0)
 464                         goto found;
 465         }
 466
 467         if (strcmp(subsystem, "module") == 0) {
 468                 strlcpy(path, "/module/", sizeof(path_full) - sysfs_len);
 469                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 470                 if (stat(path_full, &statbuf) == 0)
 471                         goto found;
 472                 goto out;
 473         }
 474
 475         if (strcmp(subsystem, "drivers") == 0) {
 476                 char subsys[NAME_SIZE];
 477                 char *driver;
 478
 479                 strlcpy(subsys, id, sizeof(subsys));
 480                 driver = strchr(subsys, ':');
 481                 if (driver != NULL) {
 482                         driver[0] = '\0';
 483                         driver = &driver[1];
 484                         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 485                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 486                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 487                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 488                         if (stat(path_full, &statbuf) == 0)
 489                                 goto found;
 490
 491                         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 492                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 493                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 494                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 495                         if (stat(path_full, &statbuf) == 0)
 496                                 goto found;
 497                 }
 498                 goto out;
 499         }
 500
 501         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 502         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 503         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 504         strlcat(path, id, sizeof(path_full) - sysfs_len);
 505         if (stat(path_full, &statbuf) == 0)
 506                 goto found;
 507
 508         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 509         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 510         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 511         strlcat(path, id, sizeof(path_full) - sysfs_len);
 512         if (stat(path_full, &statbuf) == 0)
 513                 goto found;
 514
 515         strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 516         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 517         strlcat(path, "/", sizeof(path_full) - sysfs_len);
 518         strlcat(path, id, sizeof(path_full) - sysfs_len);
 519         if (stat(path_full, &statbuf) == 0)
 520                 goto found;
 521 out:
 522         return 0;
 523 found:
 524         if (S_ISLNK(statbuf.st_mode))
 525                 sysfs_resolve_link(path, sizeof(path_full) - sysfs_len);
 526         strlcpy(devpath_full, path, len);
 527         return 1;
 528 }