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 char sysfs_path[PATH_SIZE];
  33
  34 /* device cache */
  35 static LIST_HEAD(dev_list);
  36
  37 /* attribute value cache */
  38 static LIST_HEAD(attr_list);
  39 struct sysfs_attr {
  40         struct list_head node;
  41         char path[PATH_SIZE];
  42         char *value;                    /* points to value_local if value is cached */
  43         char value_local[NAME_SIZE];
  44 };
  45
  46 int sysfs_init(void)
  47 {
  48         const char *env;
  49
  50         env = getenv("SYSFS_PATH");
  51         if (env) {
  52                 strlcpy(sysfs_path, env, sizeof(sysfs_path));
  53                 remove_trailing_chars(sysfs_path, '/');
  54         } else
  55                 strlcpy(sysfs_path, "/sys", sizeof(sysfs_path));
  56         dbg("sysfs_path='%s'\n", sysfs_path);
  57
  58         INIT_LIST_HEAD(&dev_list);
  59         INIT_LIST_HEAD(&attr_list);
  60         return 0;
  61 }
  62
  63 void sysfs_cleanup(void)
  64 {
  65         struct sysfs_attr *attr_loop;
  66         struct sysfs_attr *attr_temp;
  67         struct sysfs_device *dev_loop;
  68         struct sysfs_device *dev_temp;
  69
  70         list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) {
  71                 list_del(&attr_loop->node);
  72                 free(attr_loop);
  73         }
  74
  75         list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) {
  76                 list_del(&dev_loop->node);
  77                 free(dev_loop);
  78         }
  79 }
  80
  81 void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath,
  82                              const char *subsystem, const char *driver)
  83 {
  84         char *pos;
  85
  86         strlcpy(dev->devpath, devpath, sizeof(dev->devpath));
  87         if (subsystem != NULL)
  88                 strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem));
  89         if (driver != NULL)
  90                 strlcpy(dev->driver, driver, sizeof(dev->driver));
  91
  92         /* set kernel name */
  93         pos = strrchr(dev->devpath, '/');
  94         if (pos == NULL)
  95                 return;
  96         strlcpy(dev->kernel, &pos[1], sizeof(dev->kernel));
  97         dbg("kernel='%s'\n", dev->kernel);
  98
  99         /* some devices have '!' in their name, change that to '/' */
 100         pos = dev->kernel;
 101         while (pos[0] != '\0') {
 102                 if (pos[0] == '!')
 103                         pos[0] = '/';
 104                 pos++;
 105         }
 106
 107         /* get kernel number */
 108         pos = &dev->kernel[strlen(dev->kernel)];
 109         while (isdigit(pos[-1]))
 110                 pos--;
 111         strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number));
 112         dbg("kernel_number='%s'\n", dev->kernel_number);
 113 }
 114
 115 int sysfs_resolve_link(char *devpath, size_t size)
 116 {
 117         char link_path[PATH_SIZE];
 118         char link_target[PATH_SIZE];
 119         int len;
 120         int i;
 121         int back;
 122
 123         strlcpy(link_path, sysfs_path, sizeof(link_path));
 124         strlcat(link_path, devpath, sizeof(link_path));
 125         len = readlink(link_path, link_target, sizeof(link_target));
 126         if (len <= 0)
 127                 return -1;
 128         link_target[len] = '\0';
 129         dbg("path link '%s' points to '%s'\n", devpath, link_target);
 130
 131         for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
 132                 ;
 133         dbg("base '%s', tail '%s', back %i\n", devpath, &link_target[back * 3], back);
 134         for (i = 0; i <= back; i++) {
 135                 char *pos = strrchr(devpath, '/');
 136
 137                 if (pos == NULL)
 138                         return -1;
 139                 pos[0] = '\0';
 140         }
 141         dbg("after moving back '%s'\n", devpath);
 142         strlcat(devpath, "/", size);
 143         strlcat(devpath, &link_target[back * 3], size);
 144         return 0;
 145 }
 146
 147 struct sysfs_device *sysfs_device_get(const char *devpath)
 148 {
 149         char path[PATH_SIZE];
 150         char devpath_real[PATH_SIZE];
 151         struct sysfs_device *dev;
 152         struct sysfs_device *dev_loop;
 153         struct stat statbuf;
 154         char link_path[PATH_SIZE];
 155         char link_target[PATH_SIZE];
 156         int len;
 157         char *pos;
 158
 159         /* we handle only these devpathes */
 160         if (devpath != NULL &&
 161             strncmp(devpath, "/devices/", 9) != 0 &&
 162             strncmp(devpath, "/subsystem/", 11) != 0 &&
 163             strncmp(devpath, "/module/", 8) != 0 &&
 164             strncmp(devpath, "/bus/", 5) != 0 &&
 165             strncmp(devpath, "/class/", 7) != 0 &&
 166             strncmp(devpath, "/block/", 7) != 0)
 167                 return NULL;
 168
 169         dbg("open '%s'\n", devpath);
 170         strlcpy(devpath_real, devpath, sizeof(devpath_real));
 171         remove_trailing_chars(devpath_real, '/');
 172         if (devpath[0] == '\0' )
 173                 return NULL;
 174
 175         /* look for device already in cache (we never put an untranslated path in the cache) */
 176         list_for_each_entry(dev_loop, &dev_list, node) {
 177                 if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 178                         dbg("found in cache '%s'\n", dev_loop->devpath);
 179                         return dev_loop;
 180                 }
 181         }
 182
 183         /* if we got a link, resolve it to the real device */
 184         strlcpy(path, sysfs_path, sizeof(path));
 185         strlcat(path, devpath_real, sizeof(path));
 186         if (lstat(path, &statbuf) != 0) {
 187                 dbg("stat '%s' failed: %s\n", path, strerror(errno));
 188                 return NULL;
 189         }
 190         if (S_ISLNK(statbuf.st_mode)) {
 191                 if (sysfs_resolve_link(devpath_real, sizeof(devpath_real)) != 0)
 192                         return NULL;
 193
 194                 /* now look for device in cache after path translation */
 195                 list_for_each_entry(dev_loop, &dev_list, node) {
 196                         if (strcmp(dev_loop->devpath, devpath_real) == 0) {
 197                                 dbg("found in cache '%s'\n", dev_loop->devpath);
 198                                 return dev_loop;
 199                         }
 200                 }
 201         }
 202
 203         /* it is a new device */
 204         dbg("new uncached device '%s'\n", devpath_real);
 205         dev = malloc(sizeof(struct sysfs_device));
 206         if (dev == NULL)
 207                 return NULL;
 208         memset(dev, 0x00, sizeof(struct sysfs_device));
 209
 210         sysfs_device_set_values(dev, devpath_real, NULL, NULL);
 211
 212         /* get subsystem name */
 213         strlcpy(link_path, sysfs_path, sizeof(link_path));
 214         strlcat(link_path, dev->devpath, sizeof(link_path));
 215         strlcat(link_path, "/subsystem", sizeof(link_path));
 216         len = readlink(link_path, link_target, sizeof(link_target));
 217         if (len > 0) {
 218                 /* get subsystem from "subsystem" link */
 219                 link_target[len] = '\0';
 220                 dbg("subsystem link '%s' points to '%s'\n", link_path, link_target);
 221                 pos = strrchr(link_target, '/');
 222                 if (pos != NULL)
 223                         strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
 224         } else if (strstr(dev->devpath, "/drivers/") != NULL) {
 225                 strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 226         } else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 227                 strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 228         } else if (strncmp(dev->devpath, "/subsystem/", 11) == 0) {
 229                 pos = strrchr(dev->devpath, '/');
 230                 if (pos == &dev->devpath[10])
 231                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 232         } else if (strncmp(dev->devpath, "/class/", 7) == 0) {
 233                 pos = strrchr(dev->devpath, '/');
 234                 if (pos == &dev->devpath[6])
 235                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 236         } else if (strncmp(dev->devpath, "/bus/", 5) == 0) {
 237                 pos = strrchr(dev->devpath, '/');
 238                 if (pos == &dev->devpath[4])
 239                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 240         }
 241
 242         /* get driver name */
 243         strlcpy(link_path, sysfs_path, sizeof(link_path));
 244         strlcat(link_path, dev->devpath, sizeof(link_path));
 245         strlcat(link_path, "/driver", sizeof(link_path));
 246         len = readlink(link_path, link_target, sizeof(link_target));
 247         if (len > 0) {
 248                 link_target[len] = '\0';
 249                 dbg("driver link '%s' points to '%s'\n", link_path, link_target);
 250                 pos = strrchr(link_target, '/');
 251                 if (pos != NULL)
 252                         strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
 253         }
 254
 255         dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'\n", dev->devpath, dev->subsystem, dev->driver);
 256         list_add(&dev->node, &dev_list);
 257
 258         return dev;
 259 }
 260
 261 struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 262 {
 263         char parent_devpath[PATH_SIZE];
 264         char *pos;
 265
 266         dbg("open '%s'\n", dev->devpath);
 267
 268         /* look if we already know the parent */
 269         if (dev->parent != NULL)
 270                 return dev->parent;
 271
 272         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 273         dbg("'%s'\n", parent_devpath);
 274
 275         /* strip last element */
 276         pos = strrchr(parent_devpath, '/');
 277         if (pos == NULL || pos == parent_devpath)
 278                 return NULL;
 279         pos[0] = '\0';
 280
 281         if (strncmp(parent_devpath, "/class", 6) == 0) {
 282                 pos = strrchr(parent_devpath, '/');
 283                 if (pos == &parent_devpath[6] || pos == parent_devpath) {
 284                         dbg("/class top level, look for device link\n");
 285                         goto device_link;
 286                 }
 287         }
 288         if (strcmp(parent_devpath, "/block") == 0) {
 289                 dbg("/block top level, look for device link\n");
 290                 goto device_link;
 291         }
 292
 293         /* are we at the top level? */
 294         pos = strrchr(parent_devpath, '/');
 295         if (pos == NULL || pos == parent_devpath)
 296                 return NULL;
 297
 298         /* get parent and remember it */
 299         dev->parent = sysfs_device_get(parent_devpath);
 300         return dev->parent;
 301
 302 device_link:
 303         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 304         strlcat(parent_devpath, "/device", sizeof(parent_devpath));
 305         if (sysfs_resolve_link(parent_devpath, sizeof(parent_devpath)) != 0)
 306                 return NULL;
 307
 308         /* get parent and remember it */
 309         dev->parent = sysfs_device_get(parent_devpath);
 310         return dev->parent;
 311 }
 312
 313 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct sysfs_device *dev, const char *subsystem)
 314 {
 315         struct sysfs_device *dev_parent;
 316
 317         dev_parent = sysfs_device_get_parent(dev);
 318         while (dev_parent != NULL) {
 319                 if (strcmp(dev_parent->subsystem, subsystem) == 0)
 320                         return dev_parent;
 321                 dev_parent = sysfs_device_get_parent(dev_parent);
 322         }
 323         return NULL;
 324 }
 325
 326 char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 327 {
 328         char path_full[PATH_SIZE];
 329         const char *path;
 330         char value[NAME_SIZE];
 331         struct sysfs_attr *attr_loop;
 332         struct sysfs_attr *attr;
 333         struct stat statbuf;
 334         int fd;
 335         ssize_t size;
 336         size_t sysfs_len;
 337
 338         dbg("open '%s'/'%s'\n", devpath, attr_name);
 339         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 340         if(sysfs_len >= sizeof(path_full))
 341                 sysfs_len = sizeof(path_full) - 1;
 342         path = &path_full[sysfs_len];
 343         strlcat(path_full, devpath, sizeof(path_full));
 344         strlcat(path_full, "/", sizeof(path_full));
 345         strlcat(path_full, attr_name, sizeof(path_full));
 346
 347         /* look for attribute in cache */
 348         list_for_each_entry(attr_loop, &attr_list, node) {
 349                 if (strcmp(attr_loop->path, path) == 0) {
 350                         dbg("found in cache '%s'\n", attr_loop->path);
 351                         return attr_loop->value;
 352                 }
 353         }
 354
 355         /* store attribute in cache (also negatives are kept in cache) */
 356         dbg("new uncached attribute '%s'\n", path_full);
 357         attr = malloc(sizeof(struct sysfs_attr));
 358         if (attr == NULL)
 359                 return NULL;
 360         memset(attr, 0x00, sizeof(struct sysfs_attr));
 361         strlcpy(attr->path, path, sizeof(attr->path));
 362         dbg("add to cache '%s'\n", path_full);
 363         list_add(&attr->node, &attr_list);
 364
 365         if (lstat(path_full, &statbuf) != 0) {
 366                 dbg("stat '%s' failed: %s\n", path_full, strerror(errno));
 367                 goto out;
 368         }
 369
 370         if (S_ISLNK(statbuf.st_mode)) {
 371                 /* links return the last element of the target path */
 372                 char link_target[PATH_SIZE];
 373                 int len;
 374                 const char *pos;
 375
 376                 len = readlink(path_full, link_target, sizeof(link_target));
 377                 if (len > 0) {
 378                         link_target[len] = '\0';
 379                         pos = strrchr(link_target, '/');
 380                         if (pos != NULL) {
 381                                 dbg("cache '%s' with link value '%s'\n", path_full, value);
 382                                 strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
 383                                 attr->value = attr->value_local;
 384                         }
 385                 }
 386                 goto out;
 387         }
 388
 389         /* skip directories */
 390         if (S_ISDIR(statbuf.st_mode))
 391                 goto out;
 392
 393         /* skip non-readable files */
 394         if ((statbuf.st_mode & S_IRUSR) == 0)
 395                 goto out;
 396
 397         /* read attribute value */
 398         fd = open(path_full, O_RDONLY);
 399         if (fd < 0) {
 400                 dbg("attribute '%s' can not be opened\n", path_full);
 401                 goto out;
 402         }
 403         size = read(fd, value, sizeof(value));
 404         close(fd);
 405         if (size < 0)
 406                 goto out;
 407         if (size == sizeof(value))
 408                 goto out;
 409
 410         /* got a valid value, store and return it */
 411         value[size] = '\0';
 412         remove_trailing_chars(value, '\n');
 413         dbg("cache '%s' with attribute value '%s'\n", path_full, value);
 414         strlcpy(attr->value_local, value, sizeof(attr->value_local));
 415         attr->value = attr->value_local;
 416
 417 out:
 418         return attr->value;
 419 }
 420
 421 int sysfs_lookup_devpath_by_subsys_id(char *devpath_full, size_t len, const char *subsystem, const char *id)
 422 {
 423         size_t sysfs_len;
 424         char path_full[PATH_SIZE];
 425         char *path;
 426         struct stat statbuf;
 427
 428         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 429         path = &path_full[sysfs_len];
 430
 431         if (strcmp(subsystem, "subsystem") == 0) {
 432                 strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 433                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 434                 if (stat(path_full, &statbuf) == 0)
 435                         goto found;
 436
 437                 strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 438                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 439                 if (stat(path_full, &statbuf) == 0)
 440                         goto found;
 441                 goto out;
 442
 443                 strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 444                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 445                 if (stat(path_full, &statbuf) == 0)
 446                         goto found;
 447         }
 448
 449         if (strcmp(subsystem, "module") == 0) {
 450                 strlcpy(path, "/module/", 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                 goto out;
 455         }
 456
 457         if (strcmp(subsystem, "drivers") == 0) {
 458                 char subsys[NAME_SIZE];
 459                 char *driver;
 460
 461                 strlcpy(subsys, id, sizeof(subsys));
 462                 driver = strchr(subsys, ':');
 463                 if (driver != NULL) {
 464                         driver[0] = '\0';
 465                         driver = &driver[1];
 466                         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 467                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 468                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 469                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 470                         if (stat(path_full, &statbuf) == 0)
 471                                 goto found;
 472
 473                         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 474                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 475                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 476                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 477                         if (stat(path_full, &statbuf) == 0)
 478                                 goto found;
 479                 }
 480                 goto out;
 481         }
 482
 483         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 484         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 485         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 486         strlcat(path, id, sizeof(path_full) - sysfs_len);
 487         if (stat(path_full, &statbuf) == 0)
 488                 goto found;
 489
 490         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 491         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 492         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 493         strlcat(path, id, sizeof(path_full) - sysfs_len);
 494         if (stat(path_full, &statbuf) == 0)
 495                 goto found;
 496
 497         strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 498         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 499         strlcat(path, "/", sizeof(path_full) - sysfs_len);
 500         strlcat(path, id, sizeof(path_full) - sysfs_len);
 501         if (stat(path_full, &statbuf) == 0)
 502                 goto found;
 503 out:
 504         return 0;
 505 found:
 506         if (S_ISLNK(statbuf.st_mode))
 507                 sysfs_resolve_link(path, sizeof(path_full) - sysfs_len);
 508         strlcpy(devpath_full, path, len);
 509         return 1;
 510 }