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'\n", 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'\n", 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'\n", 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'\n", 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\n", 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'\n", 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'\n", 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'\n", 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\n", 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'\n", dev_loop->devpath);
 197                                 return dev_loop;
 198                         }
 199                 }
 200         }
 201
 202         /* it is a new device */
 203         dbg("new uncached device '%s'\n", 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'\n", 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 (strstr(dev->devpath, "/drivers/") != NULL) {
 224                 strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 225         } else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 226                 strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 227         } else if (strncmp(dev->devpath, "/subsystem/", 11) == 0) {
 228                 pos = strrchr(dev->devpath, '/');
 229                 if (pos == &dev->devpath[10])
 230                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 231         } else if (strncmp(dev->devpath, "/class/", 7) == 0) {
 232                 pos = strrchr(dev->devpath, '/');
 233                 if (pos == &dev->devpath[6])
 234                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 235         } else if (strncmp(dev->devpath, "/bus/", 5) == 0) {
 236                 pos = strrchr(dev->devpath, '/');
 237                 if (pos == &dev->devpath[4])
 238                         strlcpy(dev->subsystem, "subsystem", sizeof(dev->subsystem));
 239         }
 240
 241         /* get driver name */
 242         strlcpy(link_path, sysfs_path, sizeof(link_path));
 243         strlcat(link_path, dev->devpath, sizeof(link_path));
 244         strlcat(link_path, "/driver", sizeof(link_path));
 245         len = readlink(link_path, link_target, sizeof(link_target));
 246         if (len > 0) {
 247                 link_target[len] = '\0';
 248                 dbg("driver link '%s' points to '%s'\n", link_path, link_target);
 249                 pos = strrchr(link_target, '/');
 250                 if (pos != NULL)
 251                         strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
 252         }
 253
 254         dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'\n", dev->devpath, dev->subsystem, dev->driver);
 255         list_add(&dev->node, &dev_list);
 256
 257         return dev;
 258 }
 259
 260 struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 261 {
 262         char parent_devpath[PATH_SIZE];
 263         char *pos;
 264
 265         dbg("open '%s'\n", dev->devpath);
 266
 267         /* look if we already know the parent */
 268         if (dev->parent != NULL)
 269                 return dev->parent;
 270
 271         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 272         dbg("'%s'\n", parent_devpath);
 273
 274         /* strip last element */
 275         pos = strrchr(parent_devpath, '/');
 276         if (pos == NULL || pos == parent_devpath)
 277                 return NULL;
 278         pos[0] = '\0';
 279
 280         if (strncmp(parent_devpath, "/class", 6) == 0) {
 281                 pos = strrchr(parent_devpath, '/');
 282                 if (pos == &parent_devpath[6] || pos == parent_devpath) {
 283                         dbg("/class top level, look for device link\n");
 284                         goto device_link;
 285                 }
 286         }
 287         if (strcmp(parent_devpath, "/block") == 0) {
 288                 dbg("/block top level, look for device link\n");
 289                 goto device_link;
 290         }
 291
 292         /* are we at the top level? */
 293         pos = strrchr(parent_devpath, '/');
 294         if (pos == NULL || pos == parent_devpath)
 295                 return NULL;
 296
 297         /* get parent and remember it */
 298         dev->parent = sysfs_device_get(parent_devpath);
 299         return dev->parent;
 300
 301 device_link:
 302         strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
 303         strlcat(parent_devpath, "/device", sizeof(parent_devpath));
 304         if (sysfs_resolve_link(parent_devpath, sizeof(parent_devpath)) != 0)
 305                 return NULL;
 306
 307         /* get parent and remember it */
 308         dev->parent = sysfs_device_get(parent_devpath);
 309         return dev->parent;
 310 }
 311
 312 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct sysfs_device *dev, const char *subsystem)
 313 {
 314         struct sysfs_device *dev_parent;
 315
 316         dev_parent = sysfs_device_get_parent(dev);
 317         while (dev_parent != NULL) {
 318                 if (strcmp(dev_parent->subsystem, subsystem) == 0)
 319                         return dev_parent;
 320                 dev_parent = sysfs_device_get_parent(dev_parent);
 321         }
 322         return NULL;
 323 }
 324
 325 char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 326 {
 327         char path_full[PATH_SIZE];
 328         const char *path;
 329         char value[NAME_SIZE];
 330         struct sysfs_attr *attr_loop;
 331         struct sysfs_attr *attr;
 332         struct stat statbuf;
 333         int fd;
 334         ssize_t size;
 335         size_t sysfs_len;
 336
 337         dbg("open '%s'/'%s'\n", devpath, attr_name);
 338         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 339         if(sysfs_len >= sizeof(path_full))
 340                 sysfs_len = sizeof(path_full) - 1;
 341         path = &path_full[sysfs_len];
 342         strlcat(path_full, devpath, sizeof(path_full));
 343         strlcat(path_full, "/", sizeof(path_full));
 344         strlcat(path_full, attr_name, sizeof(path_full));
 345
 346         /* look for attribute in cache */
 347         list_for_each_entry(attr_loop, &attr_list, node) {
 348                 if (strcmp(attr_loop->path, path) == 0) {
 349                         dbg("found in cache '%s'\n", attr_loop->path);
 350                         return attr_loop->value;
 351                 }
 352         }
 353
 354         /* store attribute in cache (also negatives are kept in cache) */
 355         dbg("new uncached attribute '%s'\n", path_full);
 356         attr = malloc(sizeof(struct sysfs_attr));
 357         if (attr == NULL)
 358                 return NULL;
 359         memset(attr, 0x00, sizeof(struct sysfs_attr));
 360         strlcpy(attr->path, path, sizeof(attr->path));
 361         dbg("add to cache '%s'\n", path_full);
 362         list_add(&attr->node, &attr_list);
 363
 364         if (lstat(path_full, &statbuf) != 0) {
 365                 dbg("stat '%s' failed: %s\n", path_full, strerror(errno));
 366                 goto out;
 367         }
 368
 369         if (S_ISLNK(statbuf.st_mode)) {
 370                 /* links return the last element of the target path */
 371                 char link_target[PATH_SIZE];
 372                 int len;
 373                 const char *pos;
 374
 375                 len = readlink(path_full, link_target, sizeof(link_target));
 376                 if (len > 0) {
 377                         link_target[len] = '\0';
 378                         pos = strrchr(link_target, '/');
 379                         if (pos != NULL) {
 380                                 dbg("cache '%s' with link value '%s'\n", path_full, value);
 381                                 strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
 382                                 attr->value = attr->value_local;
 383                         }
 384                 }
 385                 goto out;
 386         }
 387
 388         /* skip directories */
 389         if (S_ISDIR(statbuf.st_mode))
 390                 goto out;
 391
 392         /* skip non-readable files */
 393         if ((statbuf.st_mode & S_IRUSR) == 0)
 394                 goto out;
 395
 396         /* read attribute value */
 397         fd = open(path_full, O_RDONLY);
 398         if (fd < 0) {
 399                 dbg("attribute '%s' can not be opened\n", path_full);
 400                 goto out;
 401         }
 402         size = read(fd, value, sizeof(value));
 403         close(fd);
 404         if (size < 0)
 405                 goto out;
 406         if (size == sizeof(value))
 407                 goto out;
 408
 409         /* got a valid value, store and return it */
 410         value[size] = '\0';
 411         remove_trailing_chars(value, '\n');
 412         dbg("cache '%s' with attribute value '%s'\n", path_full, value);
 413         strlcpy(attr->value_local, value, sizeof(attr->value_local));
 414         attr->value = attr->value_local;
 415
 416 out:
 417         return attr->value;
 418 }
 419
 420 int sysfs_lookup_devpath_by_subsys_id(char *devpath_full, size_t len, const char *subsystem, const char *id)
 421 {
 422         size_t sysfs_len;
 423         char path_full[PATH_SIZE];
 424         char *path;
 425         struct stat statbuf;
 426
 427         sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
 428         path = &path_full[sysfs_len];
 429
 430         if (strcmp(subsystem, "subsystem") == 0) {
 431                 strlcpy(path, "/subsystem/", 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                 strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 437                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 438                 if (stat(path_full, &statbuf) == 0)
 439                         goto found;
 440                 goto out;
 441
 442                 strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 443                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 444                 if (stat(path_full, &statbuf) == 0)
 445                         goto found;
 446         }
 447
 448         if (strcmp(subsystem, "module") == 0) {
 449                 strlcpy(path, "/module/", sizeof(path_full) - sysfs_len);
 450                 strlcat(path, id, sizeof(path_full) - sysfs_len);
 451                 if (stat(path_full, &statbuf) == 0)
 452                         goto found;
 453                 goto out;
 454         }
 455
 456         if (strcmp(subsystem, "drivers") == 0) {
 457                 char subsys[NAME_SIZE];
 458                 char *driver;
 459
 460                 strlcpy(subsys, id, sizeof(subsys));
 461                 driver = strchr(subsys, ':');
 462                 if (driver != NULL) {
 463                         driver[0] = '\0';
 464                         driver = &driver[1];
 465                         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 466                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 467                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 468                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 469                         if (stat(path_full, &statbuf) == 0)
 470                                 goto found;
 471
 472                         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 473                         strlcat(path, subsys, sizeof(path_full) - sysfs_len);
 474                         strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
 475                         strlcat(path, driver, sizeof(path_full) - sysfs_len);
 476                         if (stat(path_full, &statbuf) == 0)
 477                                 goto found;
 478                 }
 479                 goto out;
 480         }
 481
 482         strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
 483         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 484         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 485         strlcat(path, id, sizeof(path_full) - sysfs_len);
 486         if (stat(path_full, &statbuf) == 0)
 487                 goto found;
 488
 489         strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
 490         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 491         strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
 492         strlcat(path, id, sizeof(path_full) - sysfs_len);
 493         if (stat(path_full, &statbuf) == 0)
 494                 goto found;
 495
 496         strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
 497         strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
 498         strlcat(path, "/", sizeof(path_full) - sysfs_len);
 499         strlcat(path, id, sizeof(path_full) - sysfs_len);
 500         if (stat(path_full, &statbuf) == 0)
 501                 goto found;
 502 out:
 503         return 0;
 504 found:
 505         if (S_ISLNK(statbuf.st_mode))
 506                 sysfs_resolve_link(path, sizeof(path_full) - sysfs_len);
 507         strlcpy(devpath_full, path, len);
 508         return 1;
 509 }