lib/sysfs.c

   1 /*
   2  * No copyright is claimed.  This code is in the public domain; do with
   3  * it what you wish.
   4  *
   5  * Written by Karel Zak <kzak@redhat.com>
   6  */
   7 #include <ctype.h>
   8
   9 #include "c.h"
  10 #include "at.h"
  11 #include "pathnames.h"
  12 #include "sysfs.h"
  13 #include "fileutils.h"
  14
  15 char *sysfs_devno_attribute_path(dev_t devno, char *buf,
  16                                  size_t bufsiz, const char *attr)
  17 {
  18         int len;
  19
  20         if (attr)
  21                 len = snprintf(buf, bufsiz, _PATH_SYS_DEVBLOCK "/%d:%d/%s",
  22                         major(devno), minor(devno), attr);
  23         else
  24                 len = snprintf(buf, bufsiz, _PATH_SYS_DEVBLOCK "/%d:%d",
  25                         major(devno), minor(devno));
  26
  27         return (len < 0 || (size_t) len + 1 > bufsiz) ? NULL : buf;
  28 }
  29
  30 int sysfs_devno_has_attribute(dev_t devno, const char *attr)
  31 {
  32         char path[PATH_MAX];
  33         struct stat info;
  34
  35         if (!sysfs_devno_attribute_path(devno, path, sizeof(path), attr))
  36                 return 0;
  37         if (stat(path, &info) == 0)
  38                 return 1;
  39         return 0;
  40 }
  41
  42 char *sysfs_devno_path(dev_t devno, char *buf, size_t bufsiz)
  43 {
  44         return sysfs_devno_attribute_path(devno, buf, bufsiz, NULL);
  45 }
  46
  47 dev_t sysfs_devname_to_devno(const char *name, const char *parent)
  48 {
  49         char buf[PATH_MAX], *path = NULL;
  50         dev_t dev = 0;
  51
  52         if (strncmp("/dev/", name, 5) == 0) {
  53                 /*
  54                  * Read from /dev
  55                  */
  56                 struct stat st;
  57
  58                 if (stat(name, &st) == 0)
  59                         dev = st.st_rdev;
  60                 else
  61                         name += 5;      /* unaccesible, or not node in /dev */
  62         }
  63
  64         if (!dev && parent && strncmp("dm-", name, 3)) {
  65                 /*
  66                  * Create path to /sys/block/<parent>/<name>/dev
  67                  */
  68                 int len = snprintf(buf, sizeof(buf),
  69                                 _PATH_SYS_BLOCK "/%s/%s/dev", parent, name);
  70                 if (len < 0 || (size_t) len + 1 > sizeof(buf))
  71                         return 0;
  72                 path = buf;
  73
  74         } else if (!dev) {
  75                 /*
  76                  * Create path to /sys/block/<name>/dev
  77                  */
  78                 int len = snprintf(buf, sizeof(buf),
  79                                 _PATH_SYS_BLOCK "/%s/dev", name);
  80                 if (len < 0 || (size_t) len + 1 > sizeof(buf))
  81                         return 0;
  82                 path = buf;
  83         }
  84
  85         if (path) {
  86                 /*
  87                  * read devno from sysfs
  88                  */
  89                 FILE *f;
  90                 int maj = 0, min = 0;
  91
  92                 f = fopen(path, "r" UL_CLOEXECSTR);
  93                 if (!f)
  94                         return 0;
  95
  96                 if (fscanf(f, "%d:%d", &maj, &min) == 2)
  97                         dev = makedev(maj, min);
  98                 fclose(f);
  99         }
 100         return dev;
 101 }
 102
 103 /*
 104  * Returns devname (e.g. "/dev/sda1") for the given devno.
 105  *
 106  * Note that the @buf has to be large enough to store /sys/dev/block/<maj:min>
 107  * symlinks.
 108  *
 109  * Please, use more robust blkid_devno_to_devname() in your applications.
 110  */
 111 char *sysfs_devno_to_devpath(dev_t devno, char *buf, size_t bufsiz)
 112 {
 113         struct sysfs_cxt cxt;
 114         char *name;
 115         size_t sz;
 116         struct stat st;
 117
 118         if (sysfs_init(&cxt, devno, NULL))
 119                 return NULL;
 120
 121         name = sysfs_get_devname(&cxt, buf, bufsiz);
 122         sysfs_deinit(&cxt);
 123
 124         if (!name)
 125                 return NULL;
 126
 127         sz = strlen(name);
 128
 129         if (sz + sizeof("/dev/") > bufsiz)
 130                 return NULL;
 131
 132         /* create the final "/dev/<name>" string */
 133         memmove(buf + 5, name, sz + 1);
 134         memcpy(buf, "/dev/", 5);
 135
 136         if (!stat(buf, &st) && S_ISBLK(st.st_mode) && st.st_rdev == devno)
 137                 return buf;
 138
 139         return NULL;
 140 }
 141
 142 int sysfs_init(struct sysfs_cxt *cxt, dev_t devno, struct sysfs_cxt *parent)
 143 {
 144         char path[PATH_MAX];
 145         int fd, rc;
 146
 147         memset(cxt, 0, sizeof(*cxt));
 148         cxt->dir_fd = -1;
 149
 150         if (!sysfs_devno_path(devno, path, sizeof(path)))
 151                 goto err;
 152
 153         fd = open(path, O_RDONLY|O_CLOEXEC);
 154         if (fd < 0)
 155                 goto err;
 156         cxt->dir_fd = fd;
 157
 158         cxt->dir_path = strdup(path);
 159         if (!cxt->dir_path)
 160                 goto err;
 161         cxt->devno = devno;
 162         cxt->parent = parent;
 163         return 0;
 164 err:
 165         rc = errno > 0 ? -errno : -1;
 166         sysfs_deinit(cxt);
 167         return rc;
 168 }
 169
 170 void sysfs_deinit(struct sysfs_cxt *cxt)
 171 {
 172         if (!cxt)
 173                 return;
 174
 175         if (cxt->dir_fd >= 0)
 176                close(cxt->dir_fd);
 177         free(cxt->dir_path);
 178
 179         memset(cxt, 0, sizeof(*cxt));
 180
 181         cxt->dir_fd = -1;
 182 }
 183
 184 int sysfs_stat(struct sysfs_cxt *cxt, const char *attr, struct stat *st)
 185 {
 186         int rc = fstat_at(cxt->dir_fd, cxt->dir_path, attr, st, 0);
 187
 188         if (rc != 0 && errno == ENOENT &&
 189             strncmp(attr, "queue/", 6) == 0 && cxt->parent) {
 190
 191                 /* Exception for "queue/<attr>". These attributes are available
 192                  * for parental devices only
 193                  */
 194                 return fstat_at(cxt->parent->dir_fd,
 195                                 cxt->parent->dir_path, attr, st, 0);
 196         }
 197         return rc;
 198 }
 199
 200 int sysfs_has_attribute(struct sysfs_cxt *cxt, const char *attr)
 201 {
 202         struct stat st;
 203
 204         return sysfs_stat(cxt, attr, &st) == 0;
 205 }
 206
 207 static int sysfs_open(struct sysfs_cxt *cxt, const char *attr)
 208 {
 209         int fd = open_at(cxt->dir_fd, cxt->dir_path, attr, O_RDONLY|O_CLOEXEC);
 210
 211         if (fd == -1 && errno == ENOENT &&
 212             strncmp(attr, "queue/", 6) == 0 && cxt->parent) {
 213
 214                 /* Exception for "queue/<attr>". These attributes are available
 215                  * for parental devices only
 216                  */
 217                 fd = open_at(cxt->parent->dir_fd, cxt->dir_path, attr,
 218                                 O_RDONLY|O_CLOEXEC);
 219         }
 220         return fd;
 221 }
 222
 223 ssize_t sysfs_readlink(struct sysfs_cxt *cxt, const char *attr,
 224                    char *buf, size_t bufsiz)
 225 {
 226         if (!cxt->dir_path)
 227                 return -1;
 228
 229         if (attr)
 230                 return readlink_at(cxt->dir_fd, cxt->dir_path, attr, buf, bufsiz);
 231
 232         /* read /sys/dev/block/<maj:min> link */
 233         return readlink(cxt->dir_path, buf, bufsiz);
 234 }
 235
 236 DIR *sysfs_opendir(struct sysfs_cxt *cxt, const char *attr)
 237 {
 238         DIR *dir;
 239         int fd = -1;
 240
 241         if (attr)
 242                 fd = sysfs_open(cxt, attr);
 243
 244         else if (cxt->dir_fd >= 0)
 245                 /* request to open root of device in sysfs (/sys/block/<dev>)
 246                  * -- we cannot use cxt->sysfs_fd directly, because closedir()
 247                  * will close this our persistent file descriptor.
 248                  */
 249                 fd = dup(cxt->dir_fd);
 250
 251         if (fd < 0)
 252                 return NULL;
 253
 254         dir = fdopendir(fd);
 255         if (!dir) {
 256                 close(fd);
 257                 return NULL;
 258         }
 259         if (!attr)
 260                  rewinddir(dir);
 261         return dir;
 262 }
 263
 264
 265 static FILE *sysfs_fopen(struct sysfs_cxt *cxt, const char *attr)
 266 {
 267         int fd = sysfs_open(cxt, attr);
 268
 269         return fd < 0 ? NULL : fdopen(fd, "r" UL_CLOEXECSTR);
 270 }
 271
 272
 273 static struct dirent *xreaddir(DIR *dp)
 274 {
 275         struct dirent *d;
 276
 277         while ((d = readdir(dp))) {
 278                 if (!strcmp(d->d_name, ".") ||
 279                     !strcmp(d->d_name, ".."))
 280                         continue;
 281
 282                 /* blacklist here? */
 283                 break;
 284         }
 285         return d;
 286 }
 287
 288 int sysfs_is_partition_dirent(DIR *dir, struct dirent *d, const char *parent_name)
 289 {
 290         char path[256];
 291
 292 #ifdef _DIRENT_HAVE_D_TYPE
 293         if (d->d_type != DT_DIR &&
 294             d->d_type != DT_LNK &&
 295             d->d_type != DT_UNKNOWN)
 296                 return 0;
 297 #endif
 298         if (parent_name) {
 299                 const char *p = parent_name;
 300                 size_t len;
 301
 302                 /* /dev/sda --> "sda" */
 303                 if (*parent_name == '/') {
 304                         p = strrchr(parent_name, '/');
 305                         if (!p)
 306                                 return 0;
 307                         p++;
 308                 }
 309
 310                 len = strlen(p);
 311                 if (strlen(d->d_name) <= len)
 312                         return 0;
 313
 314                 /* partitions subdir name is
 315                  *      "<parent>[:digit:]" or "<parent>p[:digit:]"
 316                  */
 317                 return strncmp(p, d->d_name, len) == 0 &&
 318                        ((*(d->d_name + len) == 'p' && isdigit(*(d->d_name + len + 1)))
 319                         || isdigit(*(d->d_name + len)));
 320         }
 321
 322         /* Cannot use /partition file, not supported on old sysfs */
 323         snprintf(path, sizeof(path), "%s/start", d->d_name);
 324
 325         return faccessat(dirfd(dir), path, R_OK, 0) == 0;
 326 }
 327
 328 /*
 329  * Converts @partno (partition number) to devno of the partition.
 330  * The @cxt handles wholedisk device.
 331  *
 332  * Note that this code does not expect any special format of the
 333  * partitions devnames.
 334  */
 335 dev_t sysfs_partno_to_devno(struct sysfs_cxt *cxt, int partno)
 336 {
 337         DIR *dir;
 338         struct dirent *d;
 339         char path[256];
 340         dev_t devno = 0;
 341
 342         dir = sysfs_opendir(cxt, NULL);
 343         if (!dir)
 344                 return 0;
 345
 346         while ((d = xreaddir(dir))) {
 347                 int n, maj, min;
 348
 349                 if (!sysfs_is_partition_dirent(dir, d, NULL))
 350                         continue;
 351
 352                 snprintf(path, sizeof(path), "%s/partition", d->d_name);
 353                 if (sysfs_read_int(cxt, path, &n))
 354                         continue;
 355
 356                 if (n == partno) {
 357                         snprintf(path, sizeof(path), "%s/dev", d->d_name);
 358                         if (sysfs_scanf(cxt, path, "%d:%d", &maj, &min) == 2)
 359                                 devno = makedev(maj, min);
 360                         break;
 361                 }
 362         }
 363
 364         closedir(dir);
 365         return devno;
 366 }
 367
 368
 369 int sysfs_scanf(struct sysfs_cxt *cxt,  const char *attr, const char *fmt, ...)
 370 {
 371         FILE *f = sysfs_fopen(cxt, attr);
 372         va_list ap;
 373         int rc;
 374
 375         if (!f)
 376                 return -EINVAL;
 377         va_start(ap, fmt);
 378         rc = vfscanf(f, fmt, ap);
 379         va_end(ap);
 380
 381         fclose(f);
 382         return rc;
 383 }
 384
 385
 386 int sysfs_read_s64(struct sysfs_cxt *cxt, const char *attr, int64_t *res)
 387 {
 388         int64_t x = 0;
 389
 390         if (sysfs_scanf(cxt, attr, "%"SCNd64, &x) == 1) {
 391                 if (res)
 392                         *res = x;
 393                 return 0;
 394         }
 395         return -1;
 396 }
 397
 398 int sysfs_read_u64(struct sysfs_cxt *cxt, const char *attr, uint64_t *res)
 399 {
 400         uint64_t x = 0;
 401
 402         if (sysfs_scanf(cxt, attr, "%"SCNu64, &x) == 1) {
 403                 if (res)
 404                         *res = x;
 405                 return 0;
 406         }
 407         return -1;
 408 }
 409
 410 int sysfs_read_int(struct sysfs_cxt *cxt, const char *attr, int *res)
 411 {
 412         int x = 0;
 413
 414         if (sysfs_scanf(cxt, attr, "%d", &x) == 1) {
 415                 if (res)
 416                         *res = x;
 417                 return 0;
 418         }
 419         return -1;
 420 }
 421
 422 char *sysfs_strdup(struct sysfs_cxt *cxt, const char *attr)
 423 {
 424         char buf[1024];
 425         return sysfs_scanf(cxt, attr, "%1023[^\n]", buf) == 1 ?
 426                                                 strdup(buf) : NULL;
 427 }
 428
 429 int sysfs_count_dirents(struct sysfs_cxt *cxt, const char *attr)
 430 {
 431         DIR *dir;
 432         int r = 0;
 433
 434         if (!(dir = sysfs_opendir(cxt, attr)))
 435                 return 0;
 436
 437         while (xreaddir(dir)) r++;
 438
 439         closedir(dir);
 440         return r;
 441 }
 442
 443 int sysfs_count_partitions(struct sysfs_cxt *cxt, const char *devname)
 444 {
 445         DIR *dir;
 446         struct dirent *d;
 447         int r = 0;
 448
 449         if (!(dir = sysfs_opendir(cxt, NULL)))
 450                 return 0;
 451
 452         while ((d = xreaddir(dir))) {
 453                 if (sysfs_is_partition_dirent(dir, d, devname))
 454                         r++;
 455         }
 456
 457         closedir(dir);
 458         return r;
 459 }
 460
 461 /*
 462  * Returns slave name if there is only one slave, otherwise returns NULL.
 463  * The result should be deallocated by free().
 464  */
 465 char *sysfs_get_slave(struct sysfs_cxt *cxt)
 466 {
 467         DIR *dir;
 468         struct dirent *d;
 469         char *name = NULL;
 470
 471         if (!(dir = sysfs_opendir(cxt, "slaves")))
 472                 return NULL;
 473
 474         while ((d = xreaddir(dir))) {
 475                 if (name)
 476                         goto err;       /* more slaves */
 477
 478                 name = strdup(d->d_name);
 479         }
 480
 481         closedir(dir);
 482         return name;
 483 err:
 484         free(name);
 485         closedir(dir);
 486         return NULL;
 487 }
 488
 489 /*
 490  * Note that the @buf has to be large enough to store /sys/dev/block/<maj:min>
 491  * symlinks.
 492  */
 493 char *sysfs_get_devname(struct sysfs_cxt *cxt, char *buf, size_t bufsiz)
 494 {
 495         char *name = NULL;
 496         ssize_t sz;
 497
 498         sz = sysfs_readlink(cxt, NULL, buf, bufsiz - 1);
 499         if (sz < 0)
 500                 return NULL;
 501
 502         buf[sz] = '\0';
 503         name = strrchr(buf, '/');
 504         if (!name)
 505                 return NULL;
 506
 507         name++;
 508         sz = strlen(name);
 509
 510         memmove(buf, name, sz + 1);
 511         return buf;
 512 }
 513
 514 static int get_dm_wholedisk(struct sysfs_cxt *cxt, char *diskname,
 515                 size_t len, dev_t *diskdevno)
 516 {
 517     int rc = 0;
 518     char *name;
 519
 520     /* Note, sysfs_get_slave() returns the first slave only,
 521      * if there is more slaves, then return NULL
 522      */
 523     name = sysfs_get_slave(cxt);
 524     if (!name)
 525         return -1;
 526
 527     if (diskname && len) {
 528         strncpy(diskname, name, len);
 529         diskname[len - 1] = '\0';
 530     }
 531
 532     if (diskdevno) {
 533         *diskdevno = sysfs_devname_to_devno(name, NULL);
 534         if (!*diskdevno)
 535             rc = -1;
 536     }
 537
 538     free(name);
 539     return rc;
 540 }
 541
 542 int sysfs_devno_to_wholedisk(dev_t dev, char *diskname,
 543             size_t len, dev_t *diskdevno)
 544 {
 545     struct sysfs_cxt cxt;
 546     int is_part = 0;
 547
 548     if (!dev || sysfs_init(&cxt, dev, NULL) != 0)
 549         return -1;
 550
 551     is_part = sysfs_has_attribute(&cxt, "partition");
 552     if (!is_part) {
 553         /*
 554          * Extra case for partitions mapped by device-mapper.
 555          *
 556          * All regualar partitions (added by BLKPG ioctl or kernel PT
 557          * parser) have the /sys/.../partition file. The partitions
 558          * mapped by DM don't have such file, but they have "part"
 559          * prefix in DM UUID.
 560          */
 561         char *uuid = sysfs_strdup(&cxt, "dm/uuid");
 562         char *tmp = uuid;
 563         char *prefix = uuid ? strsep(&tmp, "-") : NULL;
 564
 565         if (prefix && strncasecmp(prefix, "part", 4) == 0)
 566             is_part = 1;
 567         free(uuid);
 568
 569         if (is_part &&
 570             get_dm_wholedisk(&cxt, diskname, len, diskdevno) == 0)
 571             /*
 572              * partitioned device, mapped by DM
 573              */
 574             goto done;
 575
 576         is_part = 0;
 577     }
 578
 579     if (!is_part) {
 580         /*
 581          * unpartitioned device
 582          */
 583         if (diskname && len) {
 584             if (!sysfs_get_devname(&cxt, diskname, len))
 585                 goto err;
 586         }
 587         if (diskdevno)
 588             *diskdevno = dev;
 589
 590     } else {
 591         /*
 592          * partitioned device
 593          *  - readlink /sys/dev/block/8:1   = ../../block/sda/sda1
 594          *  - dirname  ../../block/sda/sda1 = ../../block/sda
 595          *  - basename ../../block/sda      = sda
 596          */
 597         char linkpath[PATH_MAX];
 598         char *name;
 599         int linklen;
 600
 601         linklen = sysfs_readlink(&cxt, NULL,
 602                 linkpath, sizeof(linkpath) - 1);
 603         if (linklen < 0)
 604             goto err;
 605         linkpath[linklen] = '\0';
 606
 607         stripoff_last_component(linkpath);      /* dirname */
 608         name = stripoff_last_component(linkpath);   /* basename */
 609         if (!name)
 610             goto err;
 611
 612         if (diskname && len) {
 613             strncpy(diskname, name, len);
 614             diskname[len - 1] = '\0';
 615         }
 616
 617         if (diskdevno) {
 618             *diskdevno = sysfs_devname_to_devno(name, NULL);
 619             if (!*diskdevno)
 620                 goto err;
 621         }
 622     }
 623
 624 done:
 625     sysfs_deinit(&cxt);
 626     return 0;
 627 err:
 628     sysfs_deinit(&cxt);
 629     return -1;
 630 }
 631
 632
 633 int sysfs_scsi_get_hctl(struct sysfs_cxt *cxt, int *h, int *c, int *t, int *l)
 634 {
 635         char buf[PATH_MAX], *hctl;
 636         ssize_t len;
 637
 638         if (!cxt)
 639                 return -EINVAL;
 640         if (cxt->has_hctl)
 641                 goto done;
 642
 643         len = sysfs_readlink(cxt, "device", buf, sizeof(buf) - 1);
 644         if (len < 0)
 645                 return len;
 646
 647         buf[len] = '\0';
 648         hctl = strrchr(buf, '/');
 649         if (!hctl)
 650                 return -1;
 651         hctl++;
 652
 653         if (sscanf(hctl, "%u:%u:%u:%u", &cxt->scsi_host, &cxt->scsi_channel,
 654                                 &cxt->scsi_target, &cxt->scsi_lun) != 4)
 655                 return -1;
 656
 657         cxt->has_hctl = 1;
 658 done:
 659         if (h)
 660                 *h = cxt->scsi_host;
 661         if (c)
 662                 *c = cxt->scsi_channel;
 663         if (t)
 664                 *t = cxt->scsi_target;
 665         if (l)
 666                 *l = cxt->scsi_lun;
 667         return 0;
 668 }
 669
 670
 671 static char *sysfs_scsi_host_attribute_path(struct sysfs_cxt *cxt,
 672                 const char *type, char *buf, size_t bufsz, const char *attr)
 673 {
 674         int len;
 675         int host;
 676
 677         if (sysfs_scsi_get_hctl(cxt, &host, NULL, NULL, NULL))
 678                 return NULL;
 679
 680         if (attr)
 681                 len = snprintf(buf, bufsz, _PATH_SYS_CLASS "/%s_host/host%d/%s",
 682                                 type, host, attr);
 683         else
 684                 len = snprintf(buf, bufsz, _PATH_SYS_CLASS "/%s_host/host%d",
 685                                 type, host);
 686
 687         return (len < 0 || (size_t) len + 1 > bufsz) ? NULL : buf;
 688 }
 689
 690 char *sysfs_scsi_host_strdup_attribute(struct sysfs_cxt *cxt,
 691                 const char *type, const char *attr)
 692 {
 693         char buf[1024];
 694         int rc;
 695         FILE *f;
 696
 697         if (!attr || !type ||
 698             !sysfs_scsi_host_attribute_path(cxt, type, buf, sizeof(buf), attr))
 699                 return NULL;
 700
 701         if (!(f = fopen(buf, "r" UL_CLOEXECSTR)))
 702                 return NULL;
 703
 704         rc = fscanf(f, "%1023[^\n]", buf);
 705         fclose(f);
 706
 707         return rc == 1 ? strdup(buf) : NULL;
 708 }
 709
 710 int sysfs_scsi_host_is(struct sysfs_cxt *cxt, const char *type)
 711 {
 712         char buf[PATH_MAX];
 713         struct stat st;
 714
 715         if (!type || !sysfs_scsi_host_attribute_path(cxt, type,
 716                                 buf, sizeof(buf), NULL))
 717                 return 0;
 718
 719         return stat(buf, &st) == 0 && S_ISDIR(st.st_mode);
 720 }
 721
 722 static char *sysfs_scsi_attribute_path(struct sysfs_cxt *cxt,
 723                 char *buf, size_t bufsz, const char *attr)
 724 {
 725         int len, h, c, t, l;
 726
 727         if (sysfs_scsi_get_hctl(cxt, &h, &c, &t, &l) != 0)
 728                 return NULL;
 729
 730         if (attr)
 731                 len = snprintf(buf, bufsz, _PATH_SYS_SCSI "/devices/%d:%d:%d:%d/%s",
 732                                 h,c,t,l, attr);
 733         else
 734                 len = snprintf(buf, bufsz, _PATH_SYS_SCSI "/devices/%d:%d:%d:%d",
 735                                 h,c,t,l);
 736         return (len < 0 || (size_t) len + 1 > bufsz) ? NULL : buf;
 737 }
 738
 739 int sysfs_scsi_has_attribute(struct sysfs_cxt *cxt, const char *attr)
 740 {
 741         char path[PATH_MAX];
 742         struct stat st;
 743
 744         if (!sysfs_scsi_attribute_path(cxt, path, sizeof(path), attr))
 745                 return 0;
 746
 747         return stat(path, &st) == 0;
 748 }
 749
 750 int sysfs_scsi_path_contains(struct sysfs_cxt *cxt, const char *pattern)
 751 {
 752         char path[PATH_MAX], linkc[PATH_MAX];
 753         struct stat st;
 754         ssize_t len;
 755
 756         if (!sysfs_scsi_attribute_path(cxt, path, sizeof(path), NULL))
 757                 return 0;
 758
 759         if (stat(path, &st) != 0)
 760                 return 0;
 761
 762         len = readlink(path, linkc, sizeof(linkc) - 1);
 763         if (len < 0)
 764                 return 0;
 765
 766         linkc[len] = '\0';
 767         return strstr(linkc, pattern) != NULL;
 768 }
 769
 770 #ifdef TEST_PROGRAM_SYSFS
 771 #include <errno.h>
 772 #include <err.h>
 773 #include <stdlib.h>
 774
 775 int main(int argc, char *argv[])
 776 {
 777         struct sysfs_cxt cxt = UL_SYSFSCXT_EMPTY;
 778         char *devname;
 779         dev_t devno;
 780         char path[PATH_MAX];
 781         int i, is_part;
 782         uint64_t u64;
 783         ssize_t len;
 784
 785         if (argc != 2)
 786                 errx(EXIT_FAILURE, "usage: %s <devname>", argv[0]);
 787
 788         devname = argv[1];
 789         devno = sysfs_devname_to_devno(devname, NULL);
 790
 791         if (!devno)
 792                 err(EXIT_FAILURE, "failed to read devno");
 793
 794         is_part = sysfs_devno_has_attribute(devno, "partition");
 795
 796         printf("NAME: %s\n", devname);
 797         printf("DEVNO: %u (%d:%d)\n", (unsigned int) devno, major(devno), minor(devno));
 798         printf("DEVNOPATH: %s\n", sysfs_devno_path(devno, path, sizeof(path)));
 799         printf("DEVPATH: %s\n", sysfs_devno_to_devpath(devno, path, sizeof(path)));
 800         printf("PARTITION: %s\n", is_part ? "YES" : "NOT");
 801
 802         if (sysfs_init(&cxt, devno, NULL))
 803                 return EXIT_FAILURE;
 804
 805         len = sysfs_readlink(&cxt, NULL, path, sizeof(path) - 1);
 806         if (len > 0) {
 807                 path[len] = '\0';
 808                 printf("DEVNOLINK: %s\n", path);
 809         }
 810
 811         if (!is_part) {
 812                 printf("First 5 partitions:\n");
 813                 for (i = 1; i <= 5; i++) {
 814                         dev_t dev = sysfs_partno_to_devno(&cxt, i);
 815                         if (dev)
 816                                 printf("\t#%d %d:%d\n", i, major(dev), minor(dev));
 817                 }
 818         }
 819
 820         printf("SLAVES: %d\n", sysfs_count_dirents(&cxt, "slaves"));
 821
 822         if (sysfs_read_u64(&cxt, "size", &u64))
 823                 printf("read SIZE failed\n");
 824         else
 825                 printf("SIZE: %jd\n", u64);
 826
 827         if (sysfs_read_int(&cxt, "queue/hw_sector_size", &i))
 828                 printf("read SECTOR failed\n");
 829         else
 830                 printf("SECTOR: %d\n", i);
 831
 832         printf("DEVNAME: %s\n", sysfs_get_devname(&cxt, path, sizeof(path)));
 833
 834         sysfs_deinit(&cxt);
 835         return EXIT_SUCCESS;
 836 }
 837 #endif