/src/util-linux/lib/sysfs.c

Source
/*
 * No copyright is claimed.  This code is in the public domain; do with
 * it what you wish.
 *
 * Written by Karel Zak <kzak@redhat.com> [2011]
 */
#include <ctype.h>
#include <inttypes.h>
#include <libgen.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>

#include "c.h"
#include "cctype.h"
#include "pathnames.h"
#include "sysfs.h"
#include "fileutils.h"
#include "all-io.h"
#include "debug.h"
#include "strutils.h"
#include "buffer.h"

static void sysfs_blkdev_deinit_path(struct path_cxt *pc);
static int  sysfs_blkdev_enoent_redirect(struct path_cxt *pc, const char *path, int *dirfd);

/*
 * Debug stuff (based on include/debug.h)
 */
static UL_DEBUG_DEFINE_MASK(ulsysfs);
UL_DEBUG_DEFINE_MASKNAMES(ulsysfs) = UL_DEBUG_EMPTY_MASKNAMES;

#define ULSYSFS_DEBUG_INIT  (1 << 1)
#define ULSYSFS_DEBUG_CXT (1 << 2)

#define DBG(m, x)   __UL_DBG(ulsysfs, ULSYSFS_DEBUG_, m, x)
#define DBG_OBJ(m, h, x)  __UL_DBG_OBJ(ulsysfs, ULSYSFS_DEBUG_, m, h, x)
#define ON_DBG(m, x)    __UL_DBG_CALL(ulsysfs, ULSYSFS_DEBUG_, m, x)

void ul_sysfs_init_debug(void)
{
  if (ulsysfs_debug_mask)
    return;
  __UL_INIT_DEBUG_FROM_ENV(ulsysfs, ULSYSFS_DEBUG_, 0, ULSYSFS_DEBUG);
}

struct path_cxt *ul_new_sysfs_path(dev_t devno, struct path_cxt *parent, const char *prefix)
{
  struct path_cxt *pc = ul_new_path(NULL);

  if (!pc)
    return NULL;
  if (prefix)
    ul_path_set_prefix(pc, prefix);

  if (sysfs_blkdev_init_path(pc, devno, parent) != 0) {
    ul_unref_path(pc);
    return NULL;
  }

  DBG_OBJ(CXT, pc, ul_debug("alloc"));
  return pc;
}

/*
 * sysfs_blkdev_* is sysfs extension to ul_path_* API for block devices.
 *
 * The function is possible to call in loop and without sysfs_blkdev_deinit_path().
 * The sysfs_blkdev_deinit_path() is automatically called by ul_unref_path().
 *
 */
int sysfs_blkdev_init_path(struct path_cxt *pc, dev_t devno, struct path_cxt *parent)
{
  struct sysfs_blkdev *blk;
  int rc;
  char buf[sizeof(_PATH_SYS_DEVBLOCK)
     + sizeof(stringify_value(UINT32_MAX)) * 2
     + 3];

  /* define path to devno stuff */
  snprintf(buf, sizeof(buf), _PATH_SYS_DEVBLOCK "/%u:%u", major(devno), minor(devno));
  rc = ul_path_set_dir(pc, buf);
  if (rc)
    return rc;

  /* make sure path exists */
  rc = ul_path_get_dirfd(pc);
  if (rc < 0)
    return rc;

  /* initialize sysfs blkdev specific stuff */
  blk = ul_path_get_dialect(pc);
  if (!blk) {
    DBG_OBJ(CXT, pc, ul_debug("alloc new sysfs handler"));
    blk = calloc(1, sizeof(struct sysfs_blkdev));
    if (!blk)
      return -ENOMEM;

    ul_path_set_dialect(pc, blk, sysfs_blkdev_deinit_path);
    ul_path_set_enoent_redirect(pc, sysfs_blkdev_enoent_redirect);
  }

  DBG_OBJ(CXT, pc, ul_debug("init sysfs stuff"));

  blk->devno = devno;
  sysfs_blkdev_set_parent(pc, parent);

  return 0;
}

static void sysfs_blkdev_deinit_path(struct path_cxt *pc)
{
  struct sysfs_blkdev *blk;

  if (!pc)
    return;

  DBG_OBJ(CXT, pc, ul_debug("deinit"));

  blk = ul_path_get_dialect(pc);
  if (!blk)
    return;

  ul_unref_path(blk->parent);
  free(blk);

  ul_path_set_dialect(pc, NULL, NULL);
}

int sysfs_blkdev_set_parent(struct path_cxt *pc, struct path_cxt *parent)
{
  struct sysfs_blkdev *blk = ul_path_get_dialect(pc);

  if (!pc || !blk)
    return -EINVAL;

  if (blk->parent) {
    ul_unref_path(blk->parent);
    blk->parent = NULL;
  }

  if (parent) {
    ul_ref_path(parent);
    blk->parent = parent;
  } else
    blk->parent = NULL;

  DBG_OBJ(CXT, pc, ul_debug("new parent"));
  return 0;
}

struct path_cxt *sysfs_blkdev_get_parent(struct path_cxt *pc)
{
  struct sysfs_blkdev *blk = ul_path_get_dialect(pc);
  return blk ? blk->parent : NULL;
}

/*
 * Redirects ENOENT errors to the parent.
 * For example
 *
 *  /sys/dev/block/8:1/queue/logical_block_size redirects to
 *  /sys/dev/block/8:0/queue/logical_block_size
 */
static int sysfs_blkdev_enoent_redirect(struct path_cxt *pc, const char *path, int *dirfd)
{
  struct sysfs_blkdev *blk = ul_path_get_dialect(pc);

  if (blk && blk->parent && path) {
    *dirfd = ul_path_get_dirfd(blk->parent);
    if (*dirfd >= 0) {
      DBG_OBJ(CXT, pc, ul_debug("%s redirected to parent", path));
      return 0;
    }
  }
  return 1; /* no redirect */
}

char *sysfs_blkdev_get_name(struct path_cxt *pc, char *buf, size_t bufsiz)
{
  char link[PATH_MAX];
  char *name;
  ssize_t sz;

  /* read /sys/dev/block/<maj:min> link */
  sz = ul_path_readlink(pc, link, sizeof(link), NULL);
  if (sz < 0)
    return NULL;

  name = strrchr(link, '/');
  if (!name)
    return NULL;

  name++;
  sz = strlen(name);
  if ((size_t) sz + 1 > bufsiz)
    return NULL;

  memcpy(buf, name, sz + 1);
  sysfs_devname_sys_to_dev(buf);
  return buf;
}

int sysfs_blkdev_is_partition_dirent(DIR *dir, struct dirent *d, const char *parent_name)
{
  char path[NAME_MAX + 6 + 1];

#ifdef _DIRENT_HAVE_D_TYPE
  if (d->d_type != DT_DIR &&
      d->d_type != DT_LNK &&
      d->d_type != DT_UNKNOWN)
    return 0;
#endif
  size_t len = 0;

  if (parent_name) {
    const char *p = parent_name;

    /* /dev/sda --> "sda" */
    if (*parent_name == '/') {
      p = strrchr(parent_name, '/');
      if (!p)
        return 0;
      p++;
    }

    len = strlen(p);
    if ((strlen(d->d_name) <= len) || (strncmp(p, d->d_name, len) != 0))
      len = 0;
  }

  if (len > 0) {
    /* partitions subdir name is
     *  "<parent>[:digit:]" or "<parent>p[:digit:]"
     */
    return ((*(d->d_name + len) == 'p' && isdigit(*(d->d_name + len + 1)))
      || isdigit(*(d->d_name + len)));
  }

  /* Cannot use /partition file, not supported on old sysfs */
  snprintf(path, sizeof(path), "%s/start", d->d_name);

  return faccessat(dirfd(dir), path, R_OK, 0) == 0;
}

int sysfs_blkdev_count_partitions(struct path_cxt *pc, const char *devname)
{
  DIR *dir;
  struct dirent *d;
  int r = 0;

  dir = ul_path_opendir(pc, NULL);
  if (!dir)
    return 0;

  while ((d = xreaddir(dir))) {
    if (sysfs_blkdev_is_partition_dirent(dir, d, devname))
      r++;
  }

  closedir(dir);
  return r;
}

/*
 * Converts @partno (partition number) to devno of the partition.
 * The @pc handles wholedisk device.
 *
 * Note that this code does not expect any special format of the
 * partitions devnames.
 */
dev_t sysfs_blkdev_partno_to_devno(struct path_cxt *pc, int partno)
{
  DIR *dir;
  struct dirent *d;
  dev_t devno = 0;

  dir = ul_path_opendir(pc, NULL);
  if (!dir)
    return 0;

  while ((d = xreaddir(dir))) {
    int n;

    if (!sysfs_blkdev_is_partition_dirent(dir, d, NULL))
      continue;

    if (ul_path_readf_s32(pc, &n, "%s/partition", d->d_name))
      continue;

    if (n == partno) {
      if (ul_path_readf_majmin(pc, &devno, "%s/dev", d->d_name) == 0)
        break;
    }
  }

  closedir(dir);
  DBG_OBJ(CXT, pc, ul_debug("partno (%d) -> devno (%d)", (int) partno, (int) devno));
  return devno;
}


/*
 * Returns slave name if there is only one slave, otherwise returns NULL.
 * The result should be deallocated by free().
 */
char *sysfs_blkdev_get_slave(struct path_cxt *pc)
{
  DIR *dir;
  struct dirent *d;
  char *name = NULL;

  dir = ul_path_opendir(pc, "slaves");
  if (!dir)
    return NULL;

  while ((d = xreaddir(dir))) {
    if (name)
      goto err; /* more slaves */
    name = strdup(d->d_name);
  }

  closedir(dir);
  return name;
err:
  free(name);
  closedir(dir);
  return NULL;
}


#define SUBSYSTEM_LINKNAME  "/subsystem"

/*
 * For example:
 *
 * chain: /sys/dev/block/../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/ \
 *                           1-1.2:1.0/host65/target65:0:0/65:0:0:0/block/sdb
 *
 * The function check if <chain>/subsystem symlink exists, if yes then returns
 * basename of the readlink result, and remove the last subdirectory from the
 * <chain> path.
 */
static char *get_subsystem(char *chain, char *buf, size_t bufsz)
{
  size_t len;
  char *p;

  if (!chain || !*chain)
    return NULL;

  len = strlen(chain);
  if (len + sizeof(SUBSYSTEM_LINKNAME) > PATH_MAX)
    return NULL;

  do {
    ssize_t sz;

    /* append "/subsystem" to the path */
    memcpy(chain + len, SUBSYSTEM_LINKNAME, sizeof(SUBSYSTEM_LINKNAME));

    /* try if subsystem symlink exists */
    sz = readlink(chain, buf, bufsz - 1);

    /* remove last subsystem from chain */
    chain[len] = '\0';
    p = strrchr(chain, '/');
    if (p) {
      *p = '\0';
      len = p - chain;
    }

    if (sz > 0) {
      /* we found symlink to subsystem, return basename */
      buf[sz] = '\0';
      return basename(buf);
    }

  } while (p);

  return NULL;
}

/*
 * Returns complete path to the device, the path contains all subsystems
 * used for the device.
 */
char *sysfs_blkdev_get_devchain(struct path_cxt *pc, char *buf, size_t bufsz)
{
  /* read /sys/dev/block/<maj>:<min> symlink */
  ssize_t ssz;
  size_t sz = 0;
  struct ul_buffer tmp = UL_INIT_BUFFER;
  const char *p;
  char *res = NULL;

  ssz = ul_path_readlink(pc, buf, bufsz, NULL);
  if (ssz <= 0)
    return NULL;

  if ((p = ul_path_get_prefix(pc)))
    ul_buffer_append_string(&tmp, p);

  ul_buffer_append_string(&tmp, _PATH_SYS_DEVBLOCK "/");
  ul_buffer_append_data(&tmp, buf, ssz);

  p = ul_buffer_get_string(&tmp, &sz, NULL);
  if (p && sz <= bufsz) {
    memcpy(buf, p, sz);
    res = buf;
  }
  ul_buffer_free_data(&tmp);
  return res;
}

/*
 * The @subsys returns the next subsystem in the chain. Function modifies
 * @devchain string.
 *
 * Returns: 0 in success, <0 on error, 1 on end of chain
 */
int sysfs_blkdev_next_subsystem(struct path_cxt *pc __attribute__((unused)),
       char *devchain, char **subsys)
{
  char subbuf[PATH_MAX];
  char *sub;

  if (!subsys || !devchain)
    return -EINVAL;

  *subsys = NULL;

  while ((sub = get_subsystem(devchain, subbuf, sizeof(subbuf)))) {
    *subsys = strdup(sub);
    if (!*subsys)
      return -ENOMEM;
    return 0;
  }

  return 1;
}

#define REMOVABLE_FILENAME  "/removable"

/*
 * For example:
 *
 * chain: /sys/dev/block/../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/ \
 *                           1-1.2:1.0/host65/target65:0:0/65:0:0:0/block/sdb
 */
static int sysfs_devchain_is_removable(char *chain)
{
  size_t len;
  char buf[20];
  char *p;

  if (!chain || !*chain)
    return 0;

  len = strlen(chain);
  if (len + sizeof(REMOVABLE_FILENAME) > PATH_MAX)
    return 0;

  do {
    int fd, rc;

    /* append "/removable" to the path */
    memcpy(chain + len, REMOVABLE_FILENAME, sizeof(REMOVABLE_FILENAME));

    /* root of device hierarchy */
    if (strcmp(chain, "/sys/dev/block" REMOVABLE_FILENAME) == 0)
      break;

    /* try to read it */
    fd = open(chain, O_RDONLY);
    if (fd != -1) {
      rc = ul_read_all(fd, buf, sizeof(buf));
      close(fd);

      if (rc > 0) {
        if (strncmp(buf, "fixed", min(rc, 5)) == 0) {
          return 0;
        } else if (strncmp(buf, "removable", min(rc, 9)) == 0) {
          return 1;
        }
      }
    }

    /* remove last subsystem from chain */
    chain[len] = '\0';
    p = strrchr(chain, '/');
    if (p) {
      *p = '\0';
      len = p - chain;
    }

  } while (p);

  return 0;
}

int sysfs_blkdev_is_hotpluggable(struct path_cxt *pc)
{
  char buf[PATH_MAX], *chain;

  chain = sysfs_blkdev_get_devchain(pc, buf, sizeof(buf));
  return sysfs_devchain_is_removable(chain);
}

int sysfs_blkdev_is_removable(struct path_cxt *pc)
{
  int rc = 0;

  // FIXME usb is not actually removable

  /* check /sys/dev/block/<maj>:<min>/removable attribute */
  if (ul_path_read_s32(pc, &rc, "removable") == 0)
    return rc;

  return 0;
}

static int get_dm_wholedisk(struct path_cxt *pc, char *diskname,
                            size_t len, dev_t *diskdevno)
{
  int rc = 0;
  char *name;

  /* Note: sysfs_blkdev_get_slave() returns the first slave only;
   * if there are more slaves, it returns NULL.
   */
  name = sysfs_blkdev_get_slave(pc);
  if (!name)
    return -1;

  if (diskname && len)
    xstrncpy(diskname, name, len);

  if (diskdevno) {
    *diskdevno = __sysfs_devname_to_devno(ul_path_get_prefix(pc), name, NULL);
    if (!*diskdevno)
      rc = -1;
  }

  free(name);
  return rc;
}

/*
 * Returns by @diskdevno whole disk device devno and (optionally) by
 * @diskname the whole disk device name.
 */
int sysfs_blkdev_get_wholedisk( struct path_cxt *pc,
        char *diskname,
        size_t len,
        dev_t *diskdevno)
{
  int is_part = 0;

  if (!pc)
    return -1;

  is_part = ul_path_access(pc, F_OK, "partition") == 0;
  if (!is_part) {
    /*
     * Extra case for partitions mapped by device-mapper.
     *
     * All regular partitions (added by BLKPG ioctl or kernel PT
     * parser) have the /sys/.../partition file. The partitions
     * mapped by DM don't have such file, but they have "part"
     * prefix in DM UUID.
     */
    char *uuid = NULL, *tmp, *prefix;

    ul_path_read_string(pc, &uuid, "dm/uuid");
    tmp = uuid;
    prefix = uuid ? strsep(&tmp, "-") : NULL;

    if (prefix && c_strncasecmp(prefix, "part", 4) == 0)
      is_part = 1;
    free(uuid);

    if (is_part &&
      get_dm_wholedisk(pc, diskname, len, diskdevno) == 0)
      /*
       * partitioned device, mapped by DM
       */
      goto done;

    is_part = 0;
  }

  if (!is_part) {
    /*
     * unpartitioned device
     */
    if (diskname && !sysfs_blkdev_get_name(pc, diskname, len))
      goto err;
    if (diskdevno)
      *diskdevno = sysfs_blkdev_get_devno(pc);
  } else {
    /*
     * partitioned device
     *  - readlink /sys/dev/block/8:1   = ../../block/sda/sda1
     *  - dirname  ../../block/sda/sda1 = ../../block/sda
     *  - basename ../../block/sda    = sda
     */
    char linkpath[PATH_MAX];
    char *name;
    ssize_t linklen;

    linklen = ul_path_readlink(pc, linkpath, sizeof(linkpath), NULL);
    if (linklen < 0)
      goto err;

    stripoff_last_component(linkpath);    /* dirname */
    name = stripoff_last_component(linkpath);   /* basename */
    if (!name)
      goto err;

    sysfs_devname_sys_to_dev(name);
    if (diskname && len)
      xstrncpy(diskname, name, len);

    if (diskdevno) {
      *diskdevno = __sysfs_devname_to_devno(ul_path_get_prefix(pc), name, NULL);
      if (!*diskdevno)
        goto err;
    }
  }

done:
  return 0;
err:
  return -1;
}

int sysfs_devno_to_wholedisk(dev_t devno, char *diskname,
                 size_t len, dev_t *diskdevno)
{
  struct path_cxt *pc;
  int rc = 0;

  if (!devno)
    return -EINVAL;
  pc = ul_new_sysfs_path(devno, NULL, NULL);
  if (!pc)
    return -ENOMEM;

  rc = sysfs_blkdev_get_wholedisk(pc, diskname, len, diskdevno);
  ul_unref_path(pc);
  return rc;
}

/*
 * Returns 1 if the device is a hidden device-mapper device -- i.e. a device
 * that exists only as a building block for another DM target and should not
 * be opened by user-space tools (blkid, mkfs, etc.) during udev processing.
 *
 * Unlike sysfs_devno_is_dm_private(), this does NOT flag Stratis devices.
 * Stratis places its own UUID ("stratis-1-private*") in the DM uuid field,
 * but its devices are legitimately opened by tools such as mkfs.xfs to
 * obtain device geometry.
 *
 * The @uuid (if not NULL) returns DM device UUID, use free() to deallocate.
 */
int sysfs_devno_is_dm_hidden(dev_t devno, char **uuid,
           const struct ul_vfs_ops *vfs)
{
  struct path_cxt *pc = NULL;
  char *id = NULL;
  int rc = 0;

  pc = ul_new_sysfs_path(devno, NULL, NULL);
  if (!pc)
    goto done;
  ul_path_refer_vfs(pc, vfs);
  if (ul_path_read_string(pc, &id, "dm/uuid") <= 0 || !id)
    goto done;

  /* Private LVM devices use "LVM-<uuid>-<name>" uuid format (important
   * is the "LVM" prefix and "-<name>" postfix).
   */
  if (strncmp(id, "LVM-", 4) == 0) {
    char *p = strrchr(id + 4, '-');

    if (p && *(p + 1))
      rc = 1;
  }
done:
  ul_unref_path(pc);
  if (uuid)
    *uuid = id;
  else
    free(id);
  return rc;
}

/*
 * Returns 1 if the device is private device mapper device. The @uuid
 * (if not NULL) returns DM device UUID, use free() to deallocate.
 */
int sysfs_devno_is_dm_private(dev_t devno, char **uuid,
            const struct ul_vfs_ops *vfs)
{
  struct path_cxt *pc = NULL;
  char *id = NULL;
  int rc = 0;

  pc = ul_new_sysfs_path(devno, NULL, NULL);
  if (!pc)
    goto done;
  ul_path_refer_vfs(pc, vfs);
  if (ul_path_read_string(pc, &id, "dm/uuid") <= 0 || !id)
    goto done;

  /* Private LVM devices use "LVM-<uuid>-<name>" uuid format (important
   * is the "LVM" prefix and "-<name>" postfix).
   */
  if (strncmp(id, "LVM-", 4) == 0) {
    char *p = strrchr(id + 4, '-');

    if (p && *(p + 1))
      rc = 1;

  /* Private Stratis devices prefix the UUID with "stratis-1-private"
   */
  } else if (strncmp(id, "stratis-1-private", 17) == 0) {
    rc = 1;
  }
done:
  ul_unref_path(pc);
  if (uuid)
    *uuid = id;
  else
    free(id);
  return rc;
}

/*
 * Return 0 or 1, or < 0 in case of error
 */
int sysfs_devno_is_wholedisk(dev_t devno)
{
  dev_t disk;

  if (sysfs_devno_to_wholedisk(devno, NULL, 0, &disk) != 0)
    return -1;

  return devno == disk;
}


int sysfs_blkdev_scsi_get_hctl(struct path_cxt *pc, int *h, int *c, int *t, int *l)
{
  char buf[PATH_MAX], *hctl;
  struct sysfs_blkdev *blk;
  ssize_t len;

  blk = ul_path_get_dialect(pc);

  if (!blk || blk->hctl_error)
    return -EINVAL;
  if (blk->has_hctl)
    goto done;

  blk->hctl_error = 1;
  len = ul_path_readlink(pc, buf, sizeof(buf), "device");
  if (len < 0)
    return len;

  hctl = strrchr(buf, '/');
  if (!hctl)
    return -1;
  hctl++;

  if (sscanf(hctl, "%u:%u:%u:%u", &blk->scsi_host, &blk->scsi_channel,
        &blk->scsi_target, &blk->scsi_lun) != 4)
    return -1;

  blk->has_hctl = 1;
done:
  if (h)
    *h = blk->scsi_host;
  if (c)
    *c = blk->scsi_channel;
  if (t)
    *t = blk->scsi_target;
  if (l)
    *l = blk->scsi_lun;

  blk->hctl_error = 0;
  return 0;
}


static char *scsi_host_attribute_path(
      struct path_cxt *pc,
      const char *type,
      char *buf,
      size_t bufsz,
      const char *attr)
{
  int len;
  int host;
  const char *prefix;

  if (sysfs_blkdev_scsi_get_hctl(pc, &host, NULL, NULL, NULL))
    return NULL;

  prefix = ul_path_get_prefix(pc);
  if (!prefix)
    prefix = "";

  if (attr)
    len = snprintf(buf, bufsz, "%s%s/%s_host/host%d/%s",
        prefix, _PATH_SYS_CLASS, type, host, attr);
  else
    len = snprintf(buf, bufsz, "%s%s/%s_host/host%d",
        prefix, _PATH_SYS_CLASS, type, host);

  return (len < 0 || (size_t) len >= bufsz) ? NULL : buf;
}

char *sysfs_blkdev_scsi_host_strdup_attribute(struct path_cxt *pc,
      const char *type, const char *attr)
{
  char buf[1024];
  int rc;
  FILE *f;

  if (!attr || !type ||
      !scsi_host_attribute_path(pc, type, buf, sizeof(buf), attr))
    return NULL;

  if (!(f = fopen(buf, "r" UL_CLOEXECSTR)))
    return NULL;

  rc = fscanf(f, "%1023[^\n]", buf);
  fclose(f);

  return rc == 1 ? strdup(buf) : NULL;
}

int sysfs_blkdev_scsi_host_is(struct path_cxt *pc, const char *type)
{
  char buf[PATH_MAX];
  struct stat st;

  if (!type || !scsi_host_attribute_path(pc, type,
        buf, sizeof(buf), NULL))
    return 0;

  return stat(buf, &st) == 0 && S_ISDIR(st.st_mode);
}

static char *scsi_attribute_path(struct path_cxt *pc,
    char *buf, size_t bufsz, const char *attr)
{
  int len, h, c, t, l;
  const char *prefix;

  if (sysfs_blkdev_scsi_get_hctl(pc, &h, &c, &t, &l) != 0)
    return NULL;

  prefix = ul_path_get_prefix(pc);
  if (!prefix)
    prefix = "";

  if (attr)
    len = snprintf(buf, bufsz, "%s%s/devices/%d:%d:%d:%d/%s",
        prefix, _PATH_SYS_SCSI,
        h,c,t,l, attr);
  else
    len = snprintf(buf, bufsz, "%s%s/devices/%d:%d:%d:%d",
        prefix, _PATH_SYS_SCSI,
        h,c,t,l);
  return (len < 0 || (size_t) len >= bufsz) ? NULL : buf;
}

int sysfs_blkdev_scsi_has_attribute(struct path_cxt *pc, const char *attr)
{
  char path[PATH_MAX];
  struct stat st;

  if (!scsi_attribute_path(pc, path, sizeof(path), attr))
    return 0;

  return stat(path, &st) == 0;
}

int sysfs_blkdev_scsi_path_contains(struct path_cxt *pc, const char *pattern)
{
  char path[PATH_MAX], linkc[PATH_MAX];
  struct stat st;
  ssize_t len;

  if (!scsi_attribute_path(pc, path, sizeof(path), NULL))
    return 0;

  if (stat(path, &st) != 0)
    return 0;

  len = readlink(path, linkc, sizeof(linkc) - 1);
  if (len < 0)
    return 0;

  linkc[len] = '\0';
  return strstr(linkc, pattern) != NULL;
}

static dev_t read_devno(const char *path)
{
  FILE *f;
  int maj = 0, min = 0;
  dev_t dev = 0;

  f = fopen(path, "r" UL_CLOEXECSTR);
  if (!f)
    return 0;

  if (fscanf(f, "%d:%d", &maj, &min) == 2)
    dev = makedev(maj, min);
  fclose(f);
  return dev;
}

int sysfs_devname_is_hidden(const char *prefix, const char *name)
{
  char buf[PATH_MAX];
  int rc = 0, hidden = 0, len;
  FILE *f;

  if (strncmp("/dev/", name, 5) == 0)
    return 0;

  if (!prefix)
    prefix = "";
  /*
   * Create path to /sys/block/<name>/hidden
   */
  len = snprintf(buf, sizeof(buf),
      "%s" _PATH_SYS_BLOCK "/%s/hidden",
      prefix, name);

  if (len < 0 || (size_t) len + 1 > sizeof(buf))
    return 0;

  f = fopen(buf, "r" UL_CLOEXECSTR);
  if (!f)
    return 0;

  rc = fscanf(f, "%d", &hidden);
  fclose(f);

  return rc == 1 ? hidden : 0;
}


dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char *parent)
{
  char buf[PATH_MAX];
  char *_name = NULL, *_parent = NULL; /* name as encoded in sysfs */
  dev_t dev = 0;
  int len;

  if (!prefix)
    prefix = "";

  assert(name);

  if (strncmp("/dev/", name, 5) == 0) {
    /*
     * Read from /dev
     */
    struct stat st;

    if (stat(name, &st) == 0) {
      dev = st.st_rdev;
      goto done;
    }
    name += 5;  /* unaccessible, or not node in /dev */
  }

  _name = strdup(name);
  if (!_name)
    goto done;
  sysfs_devname_dev_to_sys(_name);

  if (parent) {
    _parent = strdup(parent);
    if (!_parent)
      goto done;
  }

  if (parent && strncmp("dm-", name, 3) != 0) {
    /*
     * Create path to /sys/block/<parent>/<name>/dev
     */
    sysfs_devname_dev_to_sys(_parent);
    len = snprintf(buf, sizeof(buf),
        "%s" _PATH_SYS_BLOCK "/%s/%s/dev",
        prefix, _parent, _name);
    if (len < 0 || (size_t) len >= sizeof(buf))
      goto done;

    /* don't try anything else for dm-* */
    dev = read_devno(buf);
    goto done;
  }

  /*
   * Read from /sys/block/<sysname>/dev
   */
  len = snprintf(buf, sizeof(buf),
      "%s" _PATH_SYS_BLOCK "/%s/dev",
      prefix, _name);
  if (len < 0 || (size_t) len >= sizeof(buf))
    goto done;
  dev = read_devno(buf);

  /*
   * Read from /sys/block/<parent>/<partition>/dev
   */
  if (!dev && parent && ul_startswith(name, parent)) {
    len = snprintf(buf, sizeof(buf),
        "%s" _PATH_SYS_BLOCK "/%s/%s/dev",
        prefix, _parent, _name);
    if (len < 0 || (size_t) len >= sizeof(buf))
      goto done;
    dev = read_devno(buf);
  }

  /*
   * Read from /sys/block/<sysname>/device/dev
   */
  if (!dev) {
    len = snprintf(buf, sizeof(buf),
        "%s" _PATH_SYS_BLOCK "/%s/device/dev",
        prefix, _name);
    if (len < 0 || (size_t) len >= sizeof(buf))
      goto done;
    dev = read_devno(buf);
  }
done:
  free(_name);
  free(_parent);
  return dev;
}

dev_t sysfs_devname_to_devno(const char *name)
{
  return __sysfs_devname_to_devno(NULL, name, NULL);
}

char *sysfs_blkdev_get_path(struct path_cxt *pc, char *buf, size_t bufsiz)
{
  const char *name = sysfs_blkdev_get_name(pc, buf, bufsiz);
  char *res = NULL;
  size_t sz;
  struct stat st;

  if (!name)
    goto done;

  sz = strlen(name);
  if (sz + sizeof("/dev/") > bufsiz)
    goto done;

  /* create the final "/dev/<name>" string */
  memmove(buf + 5, name, sz + 1);
  memcpy(buf, "/dev/", 5);

  if (!stat(buf, &st) && S_ISBLK(st.st_mode) && st.st_rdev == sysfs_blkdev_get_devno(pc))
    res = buf;
done:
  return res;
}

dev_t sysfs_blkdev_get_devno(struct path_cxt *pc)
{
  return ((struct sysfs_blkdev *) ul_path_get_dialect(pc))->devno;
}

/*
 * Returns devname (e.g. "/dev/sda1") for the given devno.
 *
 * Please, use more robust blkid_devno_to_devname() in your applications.
 */
char *sysfs_devno_to_devpath(dev_t devno, char *buf, size_t bufsiz)
{
  struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
  char *res = NULL;

  if (pc) {
    res = sysfs_blkdev_get_path(pc, buf, bufsiz);
    ul_unref_path(pc);
  }
  return res;
}

char *sysfs_devno_to_devname(dev_t devno, char *buf, size_t bufsiz)
{
  struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
  char *res = NULL;

  if (pc) {
    res = sysfs_blkdev_get_name(pc, buf, bufsiz);
    ul_unref_path(pc);
  }
  return res;
}

int sysfs_devno_count_partitions(dev_t devno)
{
  struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
  int n = 0;

  if (pc) {
    char buf[PATH_MAX + 1];
    char *name = sysfs_blkdev_get_name(pc, buf, sizeof(buf));

    n = sysfs_blkdev_count_partitions(pc, name);
    ul_unref_path(pc);
  }
  return n;
}

char *sysfs_chrdev_devno_to_devname(dev_t devno, char *buf, size_t bufsiz)
{
  char link[PATH_MAX];
  struct path_cxt *pc;
  char *name;
  ssize_t sz;

  pc = ul_new_path(_PATH_SYS_DEVCHAR "/%u:%u", major(devno), minor(devno));
  if (!pc)
    return NULL;

  /* read /sys/dev/char/<maj:min> link */
  sz = ul_path_readlink(pc, link, sizeof(link), NULL);
  ul_unref_path(pc);

  if (sz < 0)
    return NULL;

  name = strrchr(link, '/');
  if (!name)
    return NULL;

  name++;
  sz = strlen(name);
  if ((size_t) sz + 1 > bufsiz)
    return NULL;

  memcpy(buf, name, sz + 1);
  sysfs_devname_sys_to_dev(buf);
  return buf;

}

enum sysfs_byteorder sysfs_get_byteorder(struct path_cxt *pc)
{
  int rc;
  char buf[BUFSIZ];
  enum sysfs_byteorder ret;

  rc = ul_path_read_buffer(pc, buf, sizeof(buf), _PATH_SYS_CPU_BYTEORDER);
  if (rc < 0)
    goto unknown;

  if (strncmp(buf, "little", sizeof(buf)) == 0) {
    ret = SYSFS_BYTEORDER_LITTLE;
    goto out;
  } else if (strncmp(buf, "big", sizeof(buf)) == 0) {
    ret = SYSFS_BYTEORDER_BIG;
    goto out;
  }

unknown:
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  ret = SYSFS_BYTEORDER_LITTLE;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  ret = SYSFS_BYTEORDER_BIG;
#else
#error Unknown byte order
#endif

out:
  return ret;
}

int sysfs_get_address_bits(struct path_cxt *pc)
{
  int rc;
  int address_bits;

  rc = ul_path_scanf(pc, _PATH_SYS_ADDRESS_BITS, "%d", &address_bits);
  if (rc < 0)
    return rc;
  if (address_bits < 0)
    return -EINVAL;
  return address_bits;
}


#ifdef TEST_PROGRAM_SYSFS
#include <errno.h>
#include <err.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
  struct path_cxt *pc;
  char *devname;
  dev_t devno, disk_devno;
  char path[PATH_MAX], *sub, *chain;
  char diskname[32];
  int i, is_part, rc = EXIT_SUCCESS;
  uint64_t u64;

  if (argc != 2)
    errx(EXIT_FAILURE, "usage: %s <devname>", argv[0]);

  ul_sysfs_init_debug();

  devname = argv[1];
  devno = sysfs_devname_to_devno(devname);

  if (!devno)
    err(EXIT_FAILURE, "failed to read devno");

  printf("non-context:\n");
  printf(" DEVNO:   %u (%u:%u)\n", (unsigned int) devno, major(devno), minor(devno));
  printf(" DEVNAME: %s\n", sysfs_devno_to_devname(devno, path, sizeof(path)));
  printf(" DEVPATH: %s\n", sysfs_devno_to_devpath(devno, path, sizeof(path)));

  sysfs_devno_to_wholedisk(devno, diskname, sizeof(diskname), &disk_devno);
  printf(" WHOLEDISK-DEVNO:   %u (%u:%u)\n", (unsigned int) disk_devno, major(disk_devno), minor(disk_devno));
  printf(" WHOLEDISK-DEVNAME: %s\n", diskname);

  pc = ul_new_sysfs_path(devno, NULL, NULL);
  if (!pc)
    goto done;

  printf("context based:\n");
  devno = sysfs_blkdev_get_devno(pc);
  printf(" DEVNO:   %u (%u:%u)\n", (unsigned int) devno, major(devno), minor(devno));
  printf(" DEVNAME: %s\n", sysfs_blkdev_get_name(pc, path, sizeof(path)));
  printf(" DEVPATH: %s\n", sysfs_blkdev_get_path(pc, path, sizeof(path)));

  sysfs_devno_to_wholedisk(devno, diskname, sizeof(diskname), &disk_devno);
  printf(" WHOLEDISK-DEVNO: %u (%u:%u)\n", (unsigned int) disk_devno, major(disk_devno), minor(disk_devno));
  printf(" WHOLEDISK-DEVNAME: %s\n", diskname);

  is_part = ul_path_access(pc, F_OK, "partition") == 0;
  printf(" PARTITION: %s\n", is_part ? "YES" : "NOT");

  if (is_part && disk_devno) {
    struct path_cxt *disk_pc =  ul_new_sysfs_path(disk_devno, NULL, NULL);
    sysfs_blkdev_set_parent(pc, disk_pc);

    ul_unref_path(disk_pc);
  }

  printf(" HOTPLUG: %s\n", sysfs_blkdev_is_hotpluggable(pc) ? "yes" : "no");
  printf(" REMOVABLE: %s\n", sysfs_blkdev_is_removable(pc) ? "yes" : "no");
  printf(" SLAVES: %d\n", ul_path_count_dirents(pc, "slaves"));

  if (!is_part) {
    printf("First 5 partitions:\n");
    for (i = 1; i <= 5; i++) {
      dev_t dev = sysfs_blkdev_partno_to_devno(pc, i);
      if (dev)
        printf("\t#%d %u:%u\n", i, major(dev), minor(dev));
    }
  }

  if (ul_path_read_u64(pc, &u64, "size") != 0)
    printf(" (!) read SIZE failed\n");
  else
    printf(" SIZE: %"PRIu64"\n", u64);

  if (ul_path_read_s32(pc, &i, "queue/hw_sector_size"))
    printf(" (!) read SECTOR failed\n");
  else
    printf(" SECTOR: %d\n", i);


  chain = sysfs_blkdev_get_devchain(pc, path, sizeof(path));
  printf(" SUBSYSTEMS:\n");

  while (chain && sysfs_blkdev_next_subsystem(pc, chain, &sub) == 0) {
    printf("\t%s\n", sub);
    free(sub);
  }

  rc = EXIT_SUCCESS;
done:
  ul_unref_path(pc);
  return rc;
}
#endif /* TEST_PROGRAM_SYSFS */

Coverage Report

Created: 2026-07-16 06:58