/src/lvm2/libdm/libdm-common.c

Source
/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2025 Red Hat, Inc. All rights reserved.
 *
 * This file is part of the device-mapper userspace tools.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libdm/misc/dmlib.h"
#include "libdm/ioctl/libdm-targets.h"
#include "libdm-common.h"
#include "libdm/misc/kdev_t.h"
#include "libdm/misc/dm-ioctl.h"

#include <stdarg.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <dirent.h>

#ifdef UDEV_SYNC_SUPPORT
#  include <sys/types.h>
#  include <sys/ipc.h>
#  include <sys/sem.h>
#  include <libudev.h>
#endif

#ifdef __linux__
#  include <linux/fs.h>
#endif

#ifdef HAVE_SELINUX
#  include <selinux/selinux.h>
#endif
#ifdef HAVE_SELINUX_LABEL_H
#  include <selinux/label.h>
#endif

#define DM_DEFAULT_NAME_MANGLING_MODE_ENV_VAR_NAME "DM_DEFAULT_NAME_MANGLING_MODE"

#define DEV_DIR "/dev/"

#ifdef UDEV_SYNC_SUPPORT
#ifdef _SEM_SEMUN_UNDEFINED
union semun
{
  int val;      /* value for SETVAL */
  struct semid_ds *buf;   /* buffer for IPC_STAT & IPC_SET */
  unsigned short int *array;  /* array for GETALL & SETALL */
  struct seminfo *__buf;    /* buffer for IPC_INFO */
};
#endif
#endif

static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR;
static char _sysfs_dir[PATH_MAX] = "/sys/";
static char _path0[PATH_MAX];           /* path buffer, safe 4kB on stack */
static const char _mountinfo[] = "/proc/self/mountinfo";

#define DM_MAX_UUID_PREFIX_LEN  15
static char _default_uuid_prefix[DM_MAX_UUID_PREFIX_LEN + 1] = "LVM-";

static int _verbose = 0;
static int _suspended_dev_counter = 0;
static dm_string_mangling_t _name_mangling_mode = DEFAULT_DM_NAME_MANGLING;

#ifdef HAVE_SELINUX_LABEL_H
static struct selabel_handle *_selabel_handle = NULL;
#endif

static int _udev_disabled = 0;

#ifdef UDEV_SYNC_SUPPORT
static int _semaphore_supported = -1;
static int _udev_running = -1;
static int _sync_with_udev = 1;
static int _udev_checking = 1;
#endif

void dm_lib_init(void)
{
  const char *env;

  if (getenv("DM_DISABLE_UDEV"))
    _udev_disabled = 1;

  _name_mangling_mode = DEFAULT_DM_NAME_MANGLING;
  if ((env = getenv(DM_DEFAULT_NAME_MANGLING_MODE_ENV_VAR_NAME))) {
    if (!strcasecmp(env, "none"))
      _name_mangling_mode = DM_STRING_MANGLING_NONE;
    else if (!strcasecmp(env, "auto"))
      _name_mangling_mode = DM_STRING_MANGLING_AUTO;
    else if (!strcasecmp(env, "hex"))
      _name_mangling_mode = DM_STRING_MANGLING_HEX;
  }
}

/*
 * Library users can provide their own logging
 * function.
 */

__attribute__((format(printf, 5, 0)))
static void _default_log_line(int level, const char *file,
            int line, int dm_errno_or_class,
            const char *f, va_list ap)
{
  static int _abort_on_internal_errors = -1;
  static int _debug_with_line_numbers = -1;
  FILE *out = log_stderr(level) ? stderr : stdout;

  level = log_level(level);

  if (level <= _LOG_WARN || _verbose) {
    if (level < _LOG_WARN)
      out = stderr;

    if (_debug_with_line_numbers < 0)
      /* Set when env DM_DEBUG_WITH_LINE_NUMBERS is not "0" */
      _debug_with_line_numbers =
        strcmp(getenv("DM_DEBUG_WITH_LINE_NUMBERS") ? : "0", "0");

    if (_debug_with_line_numbers)
      fprintf(out, "%s:%d     ", file, line);

    vfprintf(out, f, ap);
    fputc('\n', out);
  }

  if (_abort_on_internal_errors < 0)
    /* Set when env DM_ABORT_ON_INTERNAL_ERRORS is not "0" */
    _abort_on_internal_errors =
      strcmp(getenv("DM_ABORT_ON_INTERNAL_ERRORS") ? : "0", "0");

  if (_abort_on_internal_errors &&
      !strncmp(f, INTERNAL_ERROR, sizeof(INTERNAL_ERROR) - 1))
    abort();
}

__attribute__((format(printf, 5, 6)))
static void _default_log_with_errno(int level,
      const char *file, int line, int dm_errno_or_class,
      const char *f, ...)
{
  va_list ap;

  va_start(ap, f);
  _default_log_line(level, file, line, dm_errno_or_class, f, ap);
  va_end(ap);
}

__attribute__((format(printf, 4, 5)))
static void _default_log(int level, const char *file,
       int line, const char *f, ...)
{
  va_list ap;

  va_start(ap, f);
  _default_log_line(level, file, line, 0, f, ap);
  va_end(ap);
}

dm_log_fn dm_log = _default_log;
dm_log_with_errno_fn dm_log_with_errno = _default_log_with_errno;

/*
 * Wrapper function to reformat new messages to and
 * old style logging which had not used errno parameter
 *
 * As we cannot simply pass '...' to old function we
 * need to process arg list locally and just pass '%s' + buffer
 */
__attribute__((format(printf, 5, 6)))
static void _log_to_default_log(int level,
      const char *file, int line, int dm_errno_or_class,
      const char *f, ...)
{
  int n;
  va_list ap;
  char buf[2 * PATH_MAX + 256]; /* big enough for most messages */

  va_start(ap, f);
  n = vsnprintf(buf, sizeof(buf), f, ap);
  va_end(ap);

  if (n > 0) /* Could be truncated */
    dm_log(level, file, line, "%s", buf);
}

/*
 * Wrapper function take 'old' style message without errno
 * and log it via new logging function with errno arg
 *
 * This minor case may happen if new libdm is used with old
 * recompiled tool that would decided to use new logging,
 * but still would like to use old binary plugins.
 */
__attribute__((format(printf, 4, 5)))
static void _log_to_default_log_with_errno(int level,
      const char *file, int line, const char *f, ...)
{
  int n;
  va_list ap;
  char buf[2 * PATH_MAX + 256]; /* big enough for most messages */

  va_start(ap, f);
  n = vsnprintf(buf, sizeof(buf), f, ap);
  va_end(ap);

  if (n > 0) /* Could be truncated */
    dm_log_with_errno(level, file, line, 0, "%s", buf);
}

void dm_log_init(dm_log_fn fn)
{
  if (fn)  {
    dm_log = fn;
    dm_log_with_errno = _log_to_default_log;
  } else {
    dm_log = _default_log;
    dm_log_with_errno = _default_log_with_errno;
  }
}

int dm_log_is_non_default(void)
{
  return (dm_log == _default_log && dm_log_with_errno == _default_log_with_errno) ? 0 : 1;
}

void dm_log_with_errno_init(dm_log_with_errno_fn fn)
{
  if (fn) {
    dm_log = _log_to_default_log_with_errno;
    dm_log_with_errno = fn;
  } else {
    dm_log = _default_log;
    dm_log_with_errno = _default_log_with_errno;
  }
}

void dm_log_init_verbose(int level)
{
  _verbose = level;
}

static int _build_dev_path(char *buffer, size_t len, const char *dev_name)
{
  int r;

  /* If there's a /, assume caller knows what they're doing */
  if (strchr(dev_name, '/'))
    r = dm_strncpy(buffer, dev_name, len);
  else
    r = (dm_snprintf(buffer, len, "%s/%s",
         _dm_dir, dev_name) < 0) ? 0 : 1;
  if (!r)
    log_error("Failed to build dev path for \"%s\".", dev_name);

  return r;
}

int dm_get_library_version(char *version, size_t size)
{
  return dm_strncpy(version, DM_LIB_VERSION, size);
}

void inc_suspended(void)
{
  _suspended_dev_counter++;
  log_debug_activation("Suspended device counter increased to %d", _suspended_dev_counter);
}

void dec_suspended(void)
{
  if (!_suspended_dev_counter) {
    log_error("Attempted to decrement suspended device counter below zero.");
    return;
  }

  _suspended_dev_counter--;
  log_debug_activation("Suspended device counter reduced to %d", _suspended_dev_counter);
}

int dm_get_suspended_counter(void)
{
  return _suspended_dev_counter;
}

int dm_set_name_mangling_mode(dm_string_mangling_t name_mangling_mode)
{
  _name_mangling_mode = name_mangling_mode;

  return 1;
}

dm_string_mangling_t dm_get_name_mangling_mode(void)
{
  return _name_mangling_mode;
}

struct dm_task *dm_task_create(int type)
{
  struct dm_task *dmt = dm_zalloc(sizeof(*dmt));

  if (!dmt) {
    log_error("dm_task_create: malloc(%" PRIsize_t ") failed",
        sizeof(*dmt));
    return NULL;
  }

  if (!dm_check_version()) {
    dm_free(dmt);
    return_NULL;
  }

  dmt->type = type;
  dmt->minor = -1;
  dmt->major = -1;
  dmt->allow_default_major_fallback = 1;
  dmt->uid = DM_DEVICE_UID;
  dmt->gid = DM_DEVICE_GID;
  dmt->mode = DM_DEVICE_MODE;
  dmt->no_open_count = 0;
  dmt->read_ahead = DM_READ_AHEAD_AUTO;
  dmt->read_ahead_flags = 0;
  dmt->event_nr = 0;
  dmt->cookie_set = 0;
  dmt->query_inactive_table = 0;
  dmt->new_uuid = 0;
  dmt->secure_data = 0;
  dmt->record_timestamp = 0;
  dmt->ima_measurement = 0;

  return dmt;
}

/*
 * Find the name associated with a given device number by scanning _dm_dir.
 */
static int _find_dm_name_of_device(dev_t st_rdev, char *buf, size_t buf_len)
{
  const char *name;
  char path[PATH_MAX];
  struct dirent *dirent;
  DIR *d;
  struct stat st;
  int r = 0;

  if (!(d = opendir(_dm_dir))) {
    log_sys_error("opendir", _dm_dir);
    return 0;
  }

  while ((dirent = readdir(d))) {
    name = dirent->d_name;

    if (!strcmp(name, ".") || !strcmp(name, ".."))
      continue;

    if (dm_snprintf(path, sizeof(path), "%s/%s", _dm_dir,
        name) == -1) {
      log_error("Couldn't create path for %s", name);
      continue;
    }

    if (stat(path, &st))
      continue;

    if (st.st_rdev == st_rdev) {
      strncpy(buf, name, buf_len);
      r = 1;
      break;
    }
  }

  if (closedir(d))
    log_sys_debug("closedir", _dm_dir);

  return r;
}

static int _is_whitelisted_char(char c)
{
  /*
   * Actually, DM supports any character in a device name.
   * This whitelist is just for proper integration with udev.
   */
        if ((c >= '0' && c <= '9') ||
            (c >= 'A' && c <= 'Z') ||
            (c >= 'a' && c <= 'z') ||
            strchr("#+-.:=@_", c) != NULL)
                return 1;

        return 0;
}

int check_multiple_mangled_string_allowed(const char *str, const char *str_name,
           dm_string_mangling_t mode)
{
  if (mode == DM_STRING_MANGLING_AUTO && strstr(str, "\\x5cx")) {
    log_error("The %s \"%s\" seems to be mangled more than once. "
        "This is not allowed in auto mode.", str_name, str);
    return 0;
  }

  return 1;
}

/*
 * Mangle all characters in the input string which are not on a whitelist
 * with '\xNN' format where NN is the hex value of the character.
 */
int mangle_string(const char *str, const char *str_name, size_t len,
      char *buf, size_t buf_len, dm_string_mangling_t mode)
{
  int need_mangling = -1; /* -1 don't know yet, 0 no, 1 yes */
  size_t i, j;

  if (!str || !buf)
    return -1;

  /* Is there anything to do at all? */
  if (!*str || !len)
    return 0;

  if (buf_len < DM_NAME_LEN) {
    log_error(INTERNAL_ERROR "mangle_string: supplied buffer too small");
    return -1;
  }

  if (mode == DM_STRING_MANGLING_NONE)
    mode = DM_STRING_MANGLING_AUTO;

  for (i = 0, j = 0; str[i]; i++) {
    if (mode == DM_STRING_MANGLING_AUTO) {
      /*
       * Detect already mangled part of the string and keep it.
       * Return error on mixture of mangled/not mangled!
       */
      if (str[i] == '\\' && str[i+1] == 'x') {
        if ((len - i < 4) || (need_mangling == 1))
          goto bad1;
        if (buf_len - j < 4)
          goto bad2;

        memcpy(&buf[j], &str[i], 4);
        i+=3; j+=4;

        need_mangling = 0;
        continue;
      }
    }

    if (_is_whitelisted_char(str[i])) {
      /* whitelisted, keep it. */
      if (buf_len - j < 1)
        goto bad2;
      buf[j] = str[i];
      j++;
    } else {
      /*
       * Not on a whitelist, mangle it.
       * Return error on mixture of mangled/not mangled
       * unless a DM_STRING_MANGLING_HEX is used!.
       */
      if ((mode != DM_STRING_MANGLING_HEX) && (need_mangling == 0))
        goto bad1;
      if (buf_len - j < 4)
        goto bad2;

      sprintf(&buf[j], "\\x%02x", (unsigned char) str[i]);
      j+=4;

      need_mangling = 1;
    }
  }

  if (buf_len - j < 1)
    goto bad2;
  buf[j] = '\0';

  /* All chars in the string whitelisted? */
  if (need_mangling == -1)
    need_mangling = 0;

  return need_mangling;

bad1:
  log_error("The %s \"%s\" contains mixed mangled and unmangled "
      "characters or it's already mangled improperly.", str_name, str);
  return -1;
bad2:
  log_error("Mangled form of the %s too long for \"%s\".", str_name, str);
  return -1;
}

/*
 * Try to unmangle supplied string.
 * Return value: -1 on error, 0 when no unmangling needed, 1 when unmangling applied
 */
int unmangle_string(const char *str, const char *str_name, size_t len,
        char *buf, size_t buf_len, dm_string_mangling_t mode)
{
  int strict = mode != DM_STRING_MANGLING_NONE;
  char str_rest[DM_NAME_LEN + 1];
  size_t i, j;
  unsigned int code;
  int r = 0;

  if (!str || !buf)
    return -1;

  /* Is there anything to do at all? */
  if (!*str || !len)
    return 0;

  if (buf_len < DM_NAME_LEN) {
    log_error(INTERNAL_ERROR "unmangle_string: supplied buffer too small");
    return -1;
  }

  for (i = 0, j = 0; str[i]; i++, j++) {
    if (strict && !(_is_whitelisted_char(str[i]) || str[i]=='\\')) {
      log_error("The %s \"%s\" should be mangled but "
          "it contains blacklisted characters.", str_name, str);
      j=0; r=-1;
      goto out;
    }

    if (str[i] == '\\' && str[i+1] == 'x') {
      if (!sscanf(&str[i+2], "%2x%" DM_TO_STRING(DM_NAME_LEN) "s",
            &code, str_rest)) {
        log_debug_activation("Hex encoding mismatch detected in %s \"%s\" "
                 "while trying to unmangle it.", str_name, str);
        goto out;
      }
      buf[j] = (unsigned char) code;

      /* skip the encoded part we've just decoded! */
      i+= 3;

      /* unmangling applied */
      r = 1;
    } else
      buf[j] = str[i];
  }

out:
  buf[j] = '\0';
  return r;
}

static int _dm_task_set_name(struct dm_task *dmt, const char *name,
           dm_string_mangling_t mangling_mode)
{
  char mangled_name[DM_NAME_LEN];
  int r = 0;

  dm_free(dmt->dev_name);
  dmt->dev_name = NULL;
  dm_free(dmt->mangled_dev_name);
  dmt->mangled_dev_name = NULL;

  if (strlen(name) >= DM_NAME_LEN) {
    log_error("Name \"%s\" too long.", name);
    return 0;
  }

  if (!check_multiple_mangled_string_allowed(name, "name", mangling_mode))
    return_0;

  if (mangling_mode != DM_STRING_MANGLING_NONE &&
      (r = mangle_string(name, "name", strlen(name), mangled_name,
             sizeof(mangled_name), mangling_mode)) < 0) {
    log_error("Failed to mangle device name \"%s\".", name);
    return 0;
  }

  /* Store mangled_dev_name only if it differs from dev_name! */
  if (r) {
    log_debug_activation("Device name mangled [%s]: %s --> %s",
             mangling_mode == DM_STRING_MANGLING_AUTO ? "auto" : "hex",
             name, mangled_name);
    if (!(dmt->mangled_dev_name = dm_strdup(mangled_name))) {
      log_error("_dm_task_set_name: dm_strdup(%s) failed", mangled_name);
      return 0;
    }
  }

  if (!(dmt->dev_name = dm_strdup(name))) {
    log_error("_dm_task_set_name: strdup(%s) failed", name);
    return 0;
  }

  return 1;
}

static int _dm_task_set_name_from_path(struct dm_task *dmt, const char *path,
               const char *name)
{
  char buf[PATH_MAX];
  struct stat st1, st2;
  const char *final_name = NULL;
  size_t len;

  if (dmt->type == DM_DEVICE_CREATE) {
    log_error("Name \"%s\" invalid. It contains \"/\".", path);
    return 0;
  }

  if (!stat(path, &st1)) {
    /*
     * Found directly.
     * If supplied path points to same device as last component
     * under /dev/mapper, use that name directly.  
     */
    if (dm_snprintf(buf, sizeof(buf), "%s/%s", _dm_dir, name) == -1) {
      log_error("Couldn't create path for %s", name);
      return 0;
    }

    if (!stat(buf, &st2) && (st1.st_rdev == st2.st_rdev))
      final_name = name;
  } else {
    /* Not found. */
    /* If there is exactly one '/' try a prefix of /dev */
    if ((len = strlen(path)) < 3 || path[0] == '/' ||
        dm_count_chars(path, len, '/') != 1) {
      log_error("Device %s not found", path);
      return 0;
    }
    if (dm_snprintf(buf, sizeof(buf), "%s/../%s", _dm_dir, path) == -1) {
      log_error("Couldn't create /dev path for %s", path);
      return 0;
    }
    if (stat(buf, &st1)) {
      log_error("Device %s not found", path);
      return 0;
    }
    /* Found */
  }

  /*
   * If we don't have the dm name yet, Call _find_dm_name_of_device() to
   * scan _dm_dir for a match.
   */
  if (!final_name) {
    if (_find_dm_name_of_device(st1.st_rdev, buf, sizeof(buf)))
      final_name = buf;
    else {
      log_error("Device %s not found", name);
      return 0;
    }
  }

  /* This is an already existing path - do not mangle! */
  return _dm_task_set_name(dmt, final_name, DM_STRING_MANGLING_NONE);
}

int dm_task_set_name(struct dm_task *dmt, const char *name)
{
  const char *pos;

  /* Path supplied for existing device? */
  if ((pos = strrchr(name, '/')))
    return _dm_task_set_name_from_path(dmt, name, pos + 1);

  return _dm_task_set_name(dmt, name, dm_get_name_mangling_mode());
}

const char *dm_task_get_name(const struct dm_task *dmt)
{
  return (dmt->dmi.v4->name);
}

static char *_task_get_string_mangled(const char *str, const char *str_name,
              char *buf, size_t buf_size,
              dm_string_mangling_t mode)
{
  char *rs;
  int r;

  if ((r = mangle_string(str, str_name, strlen(str), buf, buf_size, mode)) < 0)
    return NULL;

  if (!(rs = r ? dm_strdup(buf) : dm_strdup(str)))
    log_error("_task_get_string_mangled: dm_strdup failed");

  return rs;
}

static char *_task_get_string_unmangled(const char *str, const char *str_name,
          char *buf, size_t buf_size,
          dm_string_mangling_t mode)
{
  char *rs;
  int r = 0;

  /*
   * Unless the mode used is 'none', the string
   * is *already* unmangled on ioctl return!
   */
  if (mode == DM_STRING_MANGLING_NONE &&
      (r = unmangle_string(str, str_name, strlen(str), buf, buf_size, mode)) < 0)
    return NULL;

  if (!(rs = r ? dm_strdup(buf) : dm_strdup(str)))
    log_error("_task_get_string_unmangled: dm_strdup failed");

  return rs;
}

char *dm_task_get_name_mangled(const struct dm_task *dmt)
{
  const char *s = dm_task_get_name(dmt);
  char buf[DM_NAME_LEN];
  char *rs;

  if (!(rs = _task_get_string_mangled(s, "name", buf, sizeof(buf), dm_get_name_mangling_mode())))
    log_error("Failed to mangle device name \"%s\".", s);

  return rs;
}

char *dm_task_get_name_unmangled(const struct dm_task *dmt)
{
  const char *s = dm_task_get_name(dmt);
  char buf[DM_NAME_LEN];
  char *rs;

  if (!(rs = _task_get_string_unmangled(s, "name", buf, sizeof(buf), dm_get_name_mangling_mode())))
    log_error("Failed to unmangle device name \"%s\".", s);

  return rs;
}

const char *dm_task_get_uuid(const struct dm_task *dmt)
{
  return (dmt->dmi.v4->uuid);
}

char *dm_task_get_uuid_mangled(const struct dm_task *dmt)
{
  const char *s = dm_task_get_uuid(dmt);
  char buf[DM_UUID_LEN];
  char *rs;

  if (!(rs = _task_get_string_mangled(s, "UUID", buf, sizeof(buf), dm_get_name_mangling_mode())))
    log_error("Failed to mangle device uuid \"%s\".", s);

  return rs;
}

char *dm_task_get_uuid_unmangled(const struct dm_task *dmt)
{
  const char *s = dm_task_get_uuid(dmt);
  char buf[DM_UUID_LEN];
  char *rs;

  if (!(rs = _task_get_string_unmangled(s, "UUID", buf, sizeof(buf), dm_get_name_mangling_mode())))
    log_error("Failed to unmangle device uuid \"%s\".", s);

  return rs;
}

int dm_task_set_newname(struct dm_task *dmt, const char *newname)
{
  dm_string_mangling_t mangling_mode = dm_get_name_mangling_mode();
  char mangled_name[DM_NAME_LEN];
  int r = 0;

  if (strchr(newname, '/')) {
    log_error("Name \"%s\" invalid. It contains \"/\".", newname);
    return 0;
  }

  if (strlen(newname) >= DM_NAME_LEN) {
    log_error("Name \"%s\" too long", newname);
    return 0;
  }

  if (!*newname) {
    log_error("Non empty new name is required.");
    return 0;
  }

  if (!check_multiple_mangled_string_allowed(newname, "new name", mangling_mode))
    return_0;

  if (mangling_mode != DM_STRING_MANGLING_NONE &&
      (r = mangle_string(newname, "new name", strlen(newname), mangled_name,
             sizeof(mangled_name), mangling_mode)) < 0) {
    log_error("Failed to mangle new device name \"%s\"", newname);
    return 0;
  }

  if (r) {
    log_debug_activation("New device name mangled [%s]: %s --> %s",
             mangling_mode == DM_STRING_MANGLING_AUTO ? "auto" : "hex",
             newname, mangled_name);
    newname = mangled_name;
  }

  dm_free(dmt->newname);
  if (!(dmt->newname = dm_strdup(newname))) {
    log_error("dm_task_set_newname: strdup(%s) failed", newname);
    return 0;
  }

  dmt->new_uuid = 0;

  return 1;
}

int dm_task_set_uuid(struct dm_task *dmt, const char *uuid)
{
  char mangled_uuid[DM_UUID_LEN];
  dm_string_mangling_t mangling_mode = dm_get_name_mangling_mode();
  int r = 0;

  dm_free(dmt->uuid);
  dmt->uuid = NULL;
  dm_free(dmt->mangled_uuid);
  dmt->mangled_uuid = NULL;

  if (!check_multiple_mangled_string_allowed(uuid, "UUID", mangling_mode))
    return_0;

  if (mangling_mode != DM_STRING_MANGLING_NONE &&
      (r = mangle_string(uuid, "UUID", strlen(uuid), mangled_uuid,
             sizeof(mangled_uuid), mangling_mode)) < 0) {
    log_error("Failed to mangle device uuid \"%s\".", uuid);
    return 0;
  }

  if (r) {
    log_debug_activation("Device uuid mangled [%s]: %s --> %s",
             mangling_mode == DM_STRING_MANGLING_AUTO ? "auto" : "hex",
             uuid, mangled_uuid);

    if (!(dmt->mangled_uuid = dm_strdup(mangled_uuid))) {
      log_error("dm_task_set_uuid: dm_strdup(%s) failed", mangled_uuid);
      return 0;
    }
  }

  if (!(dmt->uuid = dm_strdup(uuid))) {
    log_error("dm_task_set_uuid: strdup(%s) failed", uuid);
    return 0;
  }

  return 1;
}

int dm_task_set_major(struct dm_task *dmt, int major)
{
  dmt->major = major;
  dmt->allow_default_major_fallback = 0;

  return 1;
}

int dm_task_set_minor(struct dm_task *dmt, int minor)
{
  dmt->minor = minor;

  return 1;
}

int dm_task_set_major_minor(struct dm_task *dmt, int major, int minor,
          int allow_default_major_fallback)
{
  dmt->major = major;
  dmt->minor = minor;
  dmt->allow_default_major_fallback = allow_default_major_fallback;

  return 1;
}

int dm_task_set_uid(struct dm_task *dmt, uid_t uid)
{
  dmt->uid = uid;

  return 1;
}

int dm_task_set_gid(struct dm_task *dmt, gid_t gid)
{
  dmt->gid = gid;

  return 1;
}

int dm_task_set_mode(struct dm_task *dmt, mode_t mode)
{
  dmt->mode = mode;

  return 1;
}

int dm_task_enable_checks(struct dm_task *dmt)
{
  dmt->enable_checks = 1;

  return 1;
}

int dm_task_add_target(struct dm_task *dmt, uint64_t start, uint64_t size,
           const char *ttype, const char *params)
{
  struct target *t = create_target(start, size, ttype, params);
  if (!t)
    return_0;

  if (!dmt->head)
    dmt->head = dmt->tail = t;
  else {
    dmt->tail->next = t;
    dmt->tail = t;
  }

  return 1;
}

#ifdef HAVE_SELINUX
static int _selabel_lookup(const char *path, mode_t mode,
         char **scontext)
{
#ifdef HAVE_SELINUX_LABEL_H
  if (!_selabel_handle &&
      !(_selabel_handle = selabel_open(SELABEL_CTX_FILE, NULL, 0))) {
    log_error("selabel_open failed: %s", strerror(errno));
    return 0;
  }

  if (selabel_lookup(_selabel_handle, scontext, path, mode)) {
    log_debug_activation("selabel_lookup failed for %s: %s",
             path, strerror(errno));
    return 0;
  }
#else
  if (matchpathcon(path, mode, scontext)) {
    log_debug_activation("matchpathcon failed for %s: %s",
             path, strerror(errno));
    return 0;
  }
#endif
  return 1;
}
#endif

#ifdef HAVE_SELINUX
static int _is_selinux_enabled(void)
{
  static int _tested = 0;
  static int _enabled;

  if (!_tested) {
    _tested = 1;
    _enabled = is_selinux_enabled();
  }

  return _enabled;
}
#endif

int dm_prepare_selinux_context(const char *path, mode_t mode)
{
#ifdef HAVE_SELINUX
  char *scontext = NULL;

  if (_is_selinux_enabled() <= 0)
    return 1;

  if (path) {
    if (!_selabel_lookup(path, mode, &scontext))
      return_0;

    log_debug_activation("Preparing SELinux context for %s to %s.", path, scontext);
  }
  else
    log_debug_activation("Resetting SELinux context to default value.");

  if (setfscreatecon(scontext) < 0) {
    log_sys_error("setfscreatecon", (path ? : "SELinux context reset"));
    freecon(scontext);
    return 0;
  }

  freecon(scontext);
#endif
  return 1;
}

int dm_set_selinux_context(const char *path, mode_t mode)
{
#ifdef HAVE_SELINUX
  char *scontext = NULL;

  if (_is_selinux_enabled() <= 0)
    return 1;

  if (!_selabel_lookup(path, mode, &scontext))
    return_0;

  log_debug_activation("Setting SELinux context for %s to %s.", path, scontext);

  if ((lsetfilecon(path, scontext) < 0) && (errno != ENOTSUP)) {
    log_sys_error("lsetfilecon", path);
    freecon(scontext);
    return 0;
  }

  freecon(scontext);
#endif
  return 1;
}

void selinux_release(void)
{
#ifdef HAVE_SELINUX_LABEL_H
  if (_selabel_handle)
    selabel_close(_selabel_handle);
  _selabel_handle = NULL;
#endif
}

static int _warn_if_op_needed(int warn_if_udev_failed)
{
    return warn_if_udev_failed && dm_udev_get_sync_support() && dm_udev_get_checking();
}

static int _add_dev_node(const char *dev_name, uint32_t major, uint32_t minor,
       uid_t uid, gid_t gid, mode_t mode, int warn_if_udev_failed)
{
  char path[PATH_MAX];
  struct stat info;
  struct stat linfo;
  dev_t dev = MKDEV(major, minor);
  mode_t old_mask;

  if (!_build_dev_path(path, sizeof(path), dev_name))
    return_0;

  /*
   * Check if the device node already exists.
   * Note: stat() follows symlinks, so this checks the target device,
   * not the symlink itself. This works correctly for both real nodes
   * and symlinks pointing to the right device.
   */
  if (stat(path, &info) >= 0) {
    if (!S_ISBLK(info.st_mode)) {
      log_error("A non-block device file at '%s' "
          "is already present", path);
      return 0;
    }

    /* If right inode already exists we don't touch uid etc. */
    if (info.st_rdev == dev) {
      /*
       * Correct device exists (either as real node or symlink).
       * Use lstat() to distinguish between them for logging.
       */
      if (lstat(path, &linfo) >= 0 && S_ISLNK(linfo.st_mode))
        log_debug_activation("Symlink %s to correct device already exists", path);
      return 1;
    }

    if (unlink(path) && (errno != ENOENT)) {
      log_sys_error("unlink", path);
      return 0;
    }
  } else {
    /*
     * stat() failed. Check for dangling symlinks (where lstat succeeds
     * but stat fails with ENOENT because the symlink target doesn't exist).
     * Remove the dangling symlink before attempting to create a new node.
     */
    if (errno == ENOENT && lstat(path, &linfo) >= 0 && S_ISLNK(linfo.st_mode)) {
      log_debug_activation("Removing dangling symlink %s", path);
      if (unlink(path) && (errno != ENOENT)) {
        log_sys_error("unlink", path);
        return 0;
      }
    }
    if (_warn_if_op_needed(warn_if_udev_failed))
      log_warn("%s not set up by udev: Falling back to direct "
         "node creation.", path);
  }

  /*
   * Test environment optimization: If using alternative dev dir (e.g., /tmp/LVMTEST/dev)
   * and the real /dev node already exists, create a symlink instead of a duplicate node.
   * This ensures operations trigger udev events which only monitors /dev.
   */
  if (strcmp(_dm_dir, DEV_DIR) != 0) {
    char real_path[PATH_MAX];
    struct stat real_stat;

    /* Build path to real /dev node (kernel always creates /dev/dm-N) */
    if (dm_snprintf(real_path, sizeof(real_path), DEV_DIR "dm-%u", minor) >= 0) {
      /* Check if real node exists with matching dev */
      if (stat(real_path, &real_stat) >= 0 &&
          S_ISBLK(real_stat.st_mode) &&
          real_stat.st_rdev == dev) {
        /*
         * Real /dev/dm-N exists. Create symlink from alternative location.
         * This allows operations to work through the symlink and trigger
         * udev events on the real device.
         */
        log_debug_activation("Creating symlink %s -> %s", path, real_path);
        (void) dm_prepare_selinux_context(path, S_IFLNK);
        if (symlink(real_path, path) < 0) {
          log_sys_error("symlink", path);
          (void) dm_prepare_selinux_context(NULL, 0);
          return 0;
        }
        (void) dm_prepare_selinux_context(NULL, 0);
        log_debug_activation("Created symlink %s -> %s", path, real_path);
        return 1;
      }
    }
  }

  (void) dm_prepare_selinux_context(path, S_IFBLK);
  old_mask = umask(0);

  /* The node may already have been created by udev. So ignore EEXIST. */
  if (mknod(path, S_IFBLK | mode, dev) < 0 && errno != EEXIST) {
    log_error("%s: mknod for %s failed: %s", path, dev_name, strerror(errno));
    umask(old_mask);
    (void) dm_prepare_selinux_context(NULL, 0);
    return 0;
  }
  umask(old_mask);
  (void) dm_prepare_selinux_context(NULL, 0);

  if (chown(path, uid, gid) < 0) {
    log_sys_error("chown", path);
    return 0;
  }

  log_debug_activation("Created %s", path);

  return 1;
}

static int _rm_dev_node(const char *dev_name, int warn_if_udev_failed)
{
  char path[PATH_MAX];
  struct stat info;

  if (!_build_dev_path(path, sizeof(path), dev_name))
    return_0;
  if (lstat(path, &info) < 0)
    return 1;
  else if (_warn_if_op_needed(warn_if_udev_failed))
    log_warn("Node %s was not removed by udev. "
       "Falling back to direct node removal.", path);

  /* udev may already have deleted the node. Ignore ENOENT. */
  if (unlink(path) && (errno != ENOENT)) {
    log_sys_error("unlink", path);
    return 0;
  }

  log_debug_activation("Removed %s", path);

  return 1;
}

static int _rename_dev_node(const char *old_name, const char *new_name,
          int warn_if_udev_failed)
{
  char oldpath[PATH_MAX];
  char newpath[PATH_MAX];
  struct stat info, info2;
  struct stat *info_block_dev;

  if (!_build_dev_path(oldpath, sizeof(oldpath), old_name) ||
      !_build_dev_path(newpath, sizeof(newpath), new_name))
    return_0;

  if (lstat(newpath, &info) == 0) {
    if (S_ISLNK(info.st_mode)) {
      if (stat(newpath, &info2) == 0)
        info_block_dev = &info2;
      else {
        log_sys_error("stat", newpath);
        return 0;
      }
    } else
      info_block_dev = &info;

    if (!S_ISBLK(info_block_dev->st_mode)) {
      log_error("A non-block device file at '%s' "
          "is already present", newpath);
      return 0;
    }
    else if (_warn_if_op_needed(warn_if_udev_failed)) {
      if (lstat(oldpath, &info) < 0 &&
         errno == ENOENT)
        /* assume udev already deleted this */
        return 1;

      log_warn("The node %s should have been renamed to %s "
         "by udev but old node is still present. "
         "Falling back to direct old node removal.",
         oldpath, newpath);
      return _rm_dev_node(old_name, 0);
    }

    if (unlink(newpath) < 0) {
      if (errno == EPERM) {
        /* devfs, entry has already been renamed */
        return 1;
      }
      log_error("Unable to unlink device node for '%s'",
          new_name);
      return 0;
    }
  }
  else if (_warn_if_op_needed(warn_if_udev_failed))
    log_warn("The node %s should have been renamed to %s "
       "by udev but new node is not present. "
       "Falling back to direct node rename.",
       oldpath, newpath);

  /* udev may already have renamed the node. Ignore ENOENT. */
  /* FIXME: when renaming to target mangling mode "none" with udev
   * while there are some blacklisted characters in the node name,
   * udev will remove the old_node, but fails to properly rename
   * to new_node. The libdevmapper code tries to call
   * rename(old_node,new_node), but that won't do anything
   * since the old node is already removed by udev.
   * For example renaming 'a\x20b' to 'a b':
   *   - udev removes 'a\x20b'
   *   - udev creates 'a' and 'b' (since it considers the ' ' as a delimiter
   *   - libdevmapper checks udev has done the rename properly
   *   - libdevmapper calls stat(new_node) and it does not see it
   *   - libdevmapper calls rename(old_node,new_node)
   *   - the rename is a NOP since the old_node does not exist anymore
   *
   * However, this situation is very rare - why would anyone need
   * to rename to an unsupported mode??? So a fix for this would be
   * just for completeness.
   */
  if (rename(oldpath, newpath) < 0 && errno != ENOENT) {
    log_error("Unable to rename device node from '%s' to '%s'",
        old_name, new_name);
    return 0;
  }

  log_debug_activation("Renamed %s to %s", oldpath, newpath);

  return 1;
}

#ifdef __linux__
static int _open_dev_node(const char *dev_name)
{
  int fd = -1;
  char path[PATH_MAX];

  if (!_build_dev_path(path, sizeof(path), dev_name))
    return fd;

  if ((fd = open(path, O_RDONLY, 0)) < 0)
    log_sys_error("open", path);

  return fd;
}

int get_dev_node_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
          uint32_t *read_ahead)
{
  char buf[24];
  int len;
  int r = 1;
  int fd;
  long read_ahead_long = 0;

  /*
   * If we know the device number, use sysfs if we can.
   * Otherwise use BLKRAGET ioctl.
   */
  if (*_sysfs_dir && major != 0) {
    if (dm_snprintf(_path0, sizeof(_path0), "%sdev/block/%" PRIu32
        ":%" PRIu32 "/bdi/read_ahead_kb", _sysfs_dir,
        major, minor) < 0) {
      log_error("Failed to build sysfs_path.");
      return 0;
    }

    if ((fd = open(_path0, O_RDONLY, 0)) != -1) {
      /* Reading from sysfs, expecting number\n */
      if ((len = read(fd, buf, sizeof(buf) - 1)) < 1) {
        log_sys_error("read", _path0);
        r = 0;
      } else {
        buf[len] = 0; /* kill \n and ensure \0 */
        *read_ahead = atoi(buf) * 2;
        log_debug_activation("%s (%d:%d): read ahead is %" PRIu32,
                 dev_name, major, minor, *read_ahead);
      }

      if (close(fd))
        log_sys_debug("close", _path0);

      return r;
    }

    log_sys_debug("open", _path0);
    /* Fall back to use dev_name */
  }

  /*
   * Open/close dev_name may block the process
   * (i.e. overfilled thin pool volume)
   */
  if (!*dev_name) {
    log_error("Empty device name passed to BLKRAGET");
    return 0;
  }

  if ((fd = _open_dev_node(dev_name)) < 0)
    return_0;

  if (ioctl(fd, BLKRAGET, &read_ahead_long)) {
    log_sys_error("BLKRAGET", dev_name);
    *read_ahead = 0;
    r = 0;
  } else {
    *read_ahead = (uint32_t) read_ahead_long;
    log_debug_activation("%s: read ahead is %" PRIu32, dev_name, *read_ahead);
  }

  if (close(fd))
    log_sys_debug("close", dev_name);

  return r;
}

static int _set_read_ahead(const char *dev_name, uint32_t major, uint32_t minor,
         uint32_t read_ahead)
{
  char buf[24];
  int len;
  int r = 1;
  int fd;
  long read_ahead_long = (long) read_ahead;

  log_debug_activation("%s (%d:%d): Setting read ahead to %" PRIu32, dev_name,
           major, minor, read_ahead);

  /*
   * If we know the device number, use sysfs if we can.
   * Otherwise use BLKRASET ioctl. RA is set after resume.
   */
  if (*_sysfs_dir && major != 0) {
    if (dm_snprintf(_path0, sizeof(_path0), "%sdev/block/%" PRIu32
        ":%" PRIu32 "/bdi/read_ahead_kb",
        _sysfs_dir, major, minor) < 0) {
      log_error("Failed to build sysfs_path.");
      return 0;
    }

    /* Sysfs is kB based, round up to kB */
    if ((len = dm_snprintf(buf, sizeof(buf), FMTu32,
               (read_ahead + 1) / 2)) < 0) {
      log_error("Failed to build size in kB.");
      return 0;
    }

    if ((fd = open(_path0, O_WRONLY, 0)) != -1) {
      if (write(fd, buf, len) < len) {
        log_sys_error("write", _path0);
        r = 0;
      }

      if (close(fd))
        log_sys_debug("close", _path0);

      return r;
    }

    log_sys_debug("open", _path0);
    /* Fall back to use dev_name */
  }

  if (!*dev_name) {
    log_error("Empty device name passed to BLKRAGET");
    return 0;
  }

  if ((fd = _open_dev_node(dev_name)) < 0)
    return_0;

  if (ioctl(fd, BLKRASET, read_ahead_long)) {
    log_sys_error("BLKRASET", dev_name);
    r = 0;
  }

  if (close(fd))
    log_sys_debug("close", dev_name);

  return r;
}

static int _set_dev_node_read_ahead(const char *dev_name,
            uint32_t major, uint32_t minor,
            uint32_t read_ahead, uint32_t read_ahead_flags)
{
  uint32_t current_read_ahead;

  if (read_ahead == DM_READ_AHEAD_AUTO)
    return 1;

  if (read_ahead == DM_READ_AHEAD_NONE)
    read_ahead = 0;

  if (read_ahead_flags & DM_READ_AHEAD_MINIMUM_FLAG) {
    if (!get_dev_node_read_ahead(dev_name, major, minor, &current_read_ahead))
      return_0;

    if (current_read_ahead >= read_ahead) {
      log_debug_activation("%s: retaining kernel read ahead of %" PRIu32
          " (requested %" PRIu32 ")",           
          dev_name, current_read_ahead, read_ahead);
      return 1;
    }
  }

  return _set_read_ahead(dev_name, major, minor, read_ahead);
}

#else

int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead)
{
  *read_ahead = 0;

  return 1;
}

static int _set_dev_node_read_ahead(const char *dev_name,
            uint32_t major, uint32_t minor,
            uint32_t read_ahead, uint32_t read_ahead_flags)
{
  return 1;
}
#endif

typedef enum {
  NODE_ADD,
  NODE_DEL,
  NODE_RENAME,
  NODE_READ_AHEAD,
  NUM_NODES
} node_op_t;

static int _do_node_op(node_op_t type, const char *dev_name, uint32_t major,
           uint32_t minor, uid_t uid, gid_t gid, mode_t mode,
           const char *old_name, uint32_t read_ahead,
           uint32_t read_ahead_flags, int warn_if_udev_failed)
{
  switch (type) {
  case NODE_ADD:
    return _add_dev_node(dev_name, major, minor, uid, gid,
             mode, warn_if_udev_failed);
  case NODE_DEL:
    return _rm_dev_node(dev_name, warn_if_udev_failed);
  case NODE_RENAME:
    return _rename_dev_node(old_name, dev_name, warn_if_udev_failed);
  case NODE_READ_AHEAD:
    return _set_dev_node_read_ahead(dev_name, major, minor,
            read_ahead, read_ahead_flags);
  default:
    ; /* NOTREACHED */
  }

  return 1;
}

static DM_LIST_INIT(_node_ops);
static int _count_node_ops[NUM_NODES];

struct node_op_parms {
  struct dm_list list;
  node_op_t type;
  char *dev_name;
  uint32_t major;
  uint32_t minor;
  uid_t uid;
  gid_t gid;
  mode_t mode;
  uint32_t read_ahead;
  uint32_t read_ahead_flags;
  char *old_name;
  int warn_if_udev_failed;
  unsigned rely_on_udev;
  char names[0];
};

static void _store_str(char **pos, char **ptr, const char *str)
{
  size_t len = strlen(str) + 1;
  memcpy(*pos, str, len);
  *ptr = *pos;
  *pos += len;
}

static void _del_node_op(struct node_op_parms *nop)
{
  _count_node_ops[nop->type]--;
  dm_list_del(&nop->list);
  dm_free(nop);

}

/* Check if there is other the type of node operation stacked */
static int _other_node_ops(node_op_t type)
{
  unsigned i;

  for (i = 0; i < NUM_NODES; i++)
    if (type != i && _count_node_ops[i])
      return 1;
  return 0;
}

static void _log_node_op(const char *action_str, struct node_op_parms *nop)
{
  const char *rely = nop->rely_on_udev ? " [trust_udev]" : "" ;
  const char *verify = nop->warn_if_udev_failed ? " [verify_udev]" : "";

  switch (nop->type) {
  case NODE_ADD:
    log_debug_activation("%s: %s NODE_ADD (%" PRIu32 ",%" PRIu32 ") %u:%u 0%o%s%s",
             nop->dev_name, action_str, nop->major, nop->minor, nop->uid, nop->gid, nop->mode,
             rely, verify);
    break;
  case NODE_DEL:
    log_debug_activation("%s: %s NODE_DEL%s%s", nop->dev_name, action_str, rely, verify);
    break;
  case NODE_RENAME:
    log_debug_activation("%s: %s NODE_RENAME to %s%s%s", nop->old_name, action_str, nop->dev_name, rely, verify);
    break;
  case NODE_READ_AHEAD:
    log_debug_activation("%s: %s NODE_READ_AHEAD %" PRIu32 " (flags=%" PRIu32 ")%s%s",
             nop->dev_name, action_str, nop->read_ahead, nop->read_ahead_flags, rely, verify);
    break;
  default:
    ; /* NOTREACHED */
  }
}

static int _stack_node_op(node_op_t type, const char *dev_name, uint32_t major,
        uint32_t minor, uid_t uid, gid_t gid, mode_t mode,
        const char *old_name, uint32_t read_ahead,
        uint32_t read_ahead_flags, int warn_if_udev_failed,
        unsigned rely_on_udev)
{
  struct node_op_parms *nop;
  struct dm_list *noph, *nopht;
  size_t len = strlen(dev_name) + strlen(old_name) + 2;
  char *pos;

  /*
   * Note: warn_if_udev_failed must have valid content
   */
  if ((type == NODE_DEL) && _other_node_ops(type))
    /*
     * Ignore any outstanding operations on the node if deleting it.
     */
    dm_list_iterate_safe(noph, nopht, &_node_ops) {
      nop = dm_list_item(noph, struct node_op_parms);
      if (!strcmp(dev_name, nop->dev_name)) {
        _log_node_op("Unstacking", nop);
        _del_node_op(nop);
        if (!_other_node_ops(type))
          break; /* no other non DEL ops */
      }
    }
  else if ((type == NODE_ADD) && _count_node_ops[NODE_DEL])
    /*
     * Ignore previous DEL operation on added node.
     * (No other operations for this device then DEL could be stacked here).
     */
    dm_list_iterate_safe(noph, nopht, &_node_ops) {
      nop = dm_list_item(noph, struct node_op_parms);
      if ((nop->type == NODE_DEL) &&
          !strcmp(dev_name, nop->dev_name)) {
        _log_node_op("Unstacking", nop);
        _del_node_op(nop);
        break; /* no other DEL ops */
      }
    }
  else if (type == NODE_RENAME)
    /*
     * Ignore any outstanding operations if renaming it.
     *
     * Currently  RENAME operation happens through 'suspend -> resume'.
     * On 'resume' device is added with read_ahead settings, so it is
     * safe to remove any stacked ADD, RENAME, READ_AHEAD operation
     * There cannot be any DEL operation on the renamed device.
     */
    dm_list_iterate_safe(noph, nopht, &_node_ops) {
      nop = dm_list_item(noph, struct node_op_parms);
      if (!strcmp(old_name, nop->dev_name)) {
        _log_node_op("Unstacking", nop);
        _del_node_op(nop);
      }
    }
  else if (type == NODE_READ_AHEAD) {
    /* udev doesn't process readahead */
    rely_on_udev = 0;
    warn_if_udev_failed = 0;
  }

  if (!(nop = dm_malloc(sizeof(*nop) + len))) {
    log_error("Insufficient memory to stack mknod operation");
    return 0;
  }

  pos = nop->names;
  nop->type = type;
  nop->major = major;
  nop->minor = minor;
  nop->uid = uid;
  nop->gid = gid;
  nop->mode = mode;
  nop->read_ahead = read_ahead;
  nop->read_ahead_flags = read_ahead_flags;
  nop->rely_on_udev = rely_on_udev;

  /*
   * Clear warn_if_udev_failed if rely_on_udev is set.  It doesn't get
   * checked in this case - this just removes the flag from log messages.
   */
  nop->warn_if_udev_failed = rely_on_udev ? 0 : warn_if_udev_failed;

  _store_str(&pos, &nop->dev_name, dev_name);
  _store_str(&pos, &nop->old_name, old_name);

  _count_node_ops[type]++;
  dm_list_add(&_node_ops, &nop->list);

  _log_node_op("Stacking", nop);

  return 1;
}

static void _pop_node_ops(void)
{
  struct dm_list *noph, *nopht;
  struct node_op_parms *nop;

  dm_list_iterate_safe(noph, nopht, &_node_ops) {
    nop = dm_list_item(noph, struct node_op_parms);
    if (!nop->rely_on_udev) {
      _log_node_op("Processing", nop);
      _do_node_op(nop->type, nop->dev_name, nop->major, nop->minor,
            nop->uid, nop->gid, nop->mode, nop->old_name,
            nop->read_ahead, nop->read_ahead_flags,
            nop->warn_if_udev_failed);
    } else
      _log_node_op("Skipping", nop);
    _del_node_op(nop);
  }
}

int add_dev_node(const char *dev_name, uint32_t major, uint32_t minor,
     uid_t uid, gid_t gid, mode_t mode, int check_udev, unsigned rely_on_udev)
{
  return _stack_node_op(NODE_ADD, dev_name, major, minor, uid,
            gid, mode, "", 0, 0, check_udev, rely_on_udev);
}

int rename_dev_node(const char *old_name, const char *new_name, int check_udev, unsigned rely_on_udev)
{
  return _stack_node_op(NODE_RENAME, new_name, 0, 0, 0,
            0, 0, old_name, 0, 0, check_udev, rely_on_udev);
}

int rm_dev_node(const char *dev_name, int check_udev, unsigned rely_on_udev)
{
  return _stack_node_op(NODE_DEL, dev_name, 0, 0, 0,
            0, 0, "", 0, 0, check_udev, rely_on_udev);
}

int set_dev_node_read_ahead(const char *dev_name,
                            uint32_t major, uint32_t minor,
          uint32_t read_ahead, uint32_t read_ahead_flags)
{
  if (read_ahead == DM_READ_AHEAD_AUTO)
    return 1;

  return _stack_node_op(NODE_READ_AHEAD, dev_name, major, minor, 0, 0,
                              0, "", read_ahead, read_ahead_flags, 0, 0);
}

void update_devs(void)
{
  _pop_node_ops();
}

static int _canonicalize_and_set_dir(const char *src, const char *suffix, size_t max_len, char *dir)
{
  size_t len;
  const char *slash;

  if (*src != '/') {
    log_debug_activation("Invalid directory value, %s: "
             "not an absolute name.", src);
    return 0;
  }

  len = strlen(src);
  slash = src[len-1] == '/' ? "" : "/";

  if (dm_snprintf(dir, max_len, "%s%s%s", src, slash, suffix ? suffix : "") < 0) {
    log_debug_activation("Invalid directory value, %s: name too long.", src);
    return 0;
  }

  return 1;
}

int dm_set_dev_dir(const char *dev_dir)
{
  return _canonicalize_and_set_dir(dev_dir, DM_DIR, sizeof _dm_dir, _dm_dir);
}

const char *dm_dir(void)
{
  return _dm_dir;
}

int dm_set_sysfs_dir(const char *sysfs_dir)
{
  if (!sysfs_dir || !*sysfs_dir) {
    _sysfs_dir[0] = '\0';
    return 1;
  }

  return _canonicalize_and_set_dir(sysfs_dir, NULL, sizeof _sysfs_dir, _sysfs_dir);
}

const char *dm_sysfs_dir(void)
{
  return _sysfs_dir;
}

/*
 * Replace existing uuid_prefix provided it isn't too long.
 */
int dm_set_uuid_prefix(const char *uuid_prefix)
{
  size_t len;

  if (!uuid_prefix)
    return_0;

  if ((len = strlen(uuid_prefix)) > DM_MAX_UUID_PREFIX_LEN) {
    log_error("New uuid prefix %s too long.", uuid_prefix);
    return 0;
  }

  memcpy(_default_uuid_prefix, uuid_prefix, len + 1);

  return 1;
}

const char *dm_uuid_prefix(void)
{
  return _default_uuid_prefix;
}

static int _is_octal(int a)
{
  return (((a) & ~7) == '0');
}

/* Convert mangled mountinfo into normal ASCII string */
static void _unmangle_mountinfo_string(const char *src, char *buf)
{
  while (*src) {
    if ((*src == '\\') &&
        _is_octal(src[1]) && _is_octal(src[2]) && _is_octal(src[3])) {
      *buf++ = 64 * (src[1] & 7) + 8 * (src[2] & 7) + (src[3] & 7);
      src += 4;
    } else
      *buf++ = *src++;
  }
  *buf = '\0';
}

/* coverity[+tainted_string_sanitize_content:arg-0] */
static int _sanitize_line(const char *line) { return 1; }

/* Parse one line of mountinfo and unmangled target line */
static int _mountinfo_parse_line(const char *line, unsigned *maj, unsigned *min, char *buf)
{
  char root[PATH_MAX + 1]; /* sscanf needs extra '\0' */
  char target[PATH_MAX + 1];
  const char *devmapper;
  struct dm_task *dmt;
  struct dm_info info;
  unsigned i;

  /* TODO: maybe detect availability of  %ms  glib support ? */
  if (sscanf(line, "%*u %*u %u:%u %" DM_TO_STRING(PATH_MAX)
       "s %" DM_TO_STRING(PATH_MAX) "s",
       maj, min, root, target) < 4) {
    log_error("Failed to parse mountinfo line.");
    return 0;
  }

  /* btrfs fakes device numbers, but there is still /dev/mapper name
   * placed in mountinfo, so try to detect proper major:minor via this */
  if (*maj == 0 && (devmapper = strstr(line, "/dev/mapper/"))) {
    if (!(dmt = dm_task_create(DM_DEVICE_INFO))) {
      log_error("Mount info task creation failed.");
      return 0;
    }
    devmapper += 12; /* skip fixed prefix */
    for (i = 0; devmapper[i] && devmapper[i] != ' ' && i < sizeof(root)-1; ++i)
      root[i] = devmapper[i];
    root[i] = 0;
    _unmangle_mountinfo_string(root, buf);
    buf[DM_NAME_LEN] = 0; /* cut away */

    if (dm_task_set_name(dmt, buf) &&
        dm_task_no_open_count(dmt) &&
        dm_task_run(dmt) &&
        dm_task_get_info(dmt, &info)) {
      log_debug("Replacing mountinfo device (%u:%u) with matching DM device %s (%u:%u).",
          *maj, *min, buf, info.major, info.minor);
      *maj = info.major;
      *min = info.minor;
    }
    dm_task_destroy(dmt);
  }

  _unmangle_mountinfo_string(target, buf);

  return 1;
}

/*
 * Function to operate on individual mountinfo line,
 * minor, major and mount target are parsed and unmangled
 */
int dm_mountinfo_read(dm_mountinfo_line_callback_fn read_fn, void *cb_data)
{
  FILE *minfo;
  char buffer[2 * PATH_MAX];
  char target[PATH_MAX];
  unsigned maj, min;
  int r = 1;

  if (!(minfo = fopen(_mountinfo, "r"))) {
    if (errno != ENOENT)
      log_sys_error("fopen", _mountinfo);
    else
      log_sys_debug("fopen", _mountinfo);
    return 0;
  }

  while (!feof(minfo) && fgets(buffer, sizeof(buffer), minfo))
    if (!_sanitize_line(buffer) ||
        !_mountinfo_parse_line(buffer, &maj, &min, target) ||
        !read_fn(buffer, maj, min, target, cb_data)) {
      stack;
      r = 0;
      break;
    }

  if (fclose(minfo))
    log_sys_error("fclose", _mountinfo);

  return r;
}

static int _sysfs_get_dm_name(uint32_t major, uint32_t minor, char *buf, size_t buf_size)
{
  char sysfs_path[PATH_MAX], temp_buf[2 * DM_NAME_LEN];
  FILE *fp = NULL;
  int r = 0;
  size_t len;

  if (dm_snprintf(sysfs_path, sizeof(sysfs_path),
      "%sdev/block/%" PRIu32 ":%" PRIu32
      "/dm/name", _sysfs_dir, major, minor) < 0) {
    log_error("_sysfs_get_dm_name: dm_snprintf failed.");
    goto bad;
  }

  if (!(fp = fopen(sysfs_path, "r"))) {
    if (errno == ENOENT)
      log_sys_debug("fopen", sysfs_path);
                else
      log_sys_error("fopen", sysfs_path);
    goto bad;
  }

  if (!fgets(temp_buf, sizeof(temp_buf), fp)) {
    log_sys_error("fgets", sysfs_path);
    goto bad;
  }

  len = strlen(temp_buf);

  if (len > buf_size) {
    log_error("_sysfs_get_dm_name: supplied buffer too small.");
    goto bad;
  }

  if (len)
    --len;  /* strip \n */

  memcpy(buf, temp_buf, len);
  buf[len] = '\0';

  r = 1;
bad:
  if (fp && fclose(fp))
    log_sys_error("fclose", sysfs_path);

  return r;
}

static int _sysfs_get_dev_major_minor(const char *path, uint32_t major, uint32_t minor)
{
  FILE *fp;
  uint32_t ma, mi;
  int r;

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

  r = (fscanf(fp, "%" PRIu32 ":%" PRIu32 , &ma, &mi) == 2) &&
    (ma == major) && (mi == minor);
  // log_debug("Checking %s  %u:%u  -> %d", path, ma, mi, r);

  if (fclose(fp))
    log_sys_error("fclose", path);

  return r;
}

static int _sysfs_find_kernel_name(uint32_t major, uint32_t minor, char *buf, size_t buf_size)
{
  const char *name, *name_dev;
  char path[PATH_MAX];
  struct dirent *dirent, *dirent_dev;
  DIR *d, *d_dev;
  struct stat st;
  int r = 0, sz;

  if (!*_sysfs_dir ||
      dm_snprintf(path, sizeof(path), "%s/block/", _sysfs_dir) < 0) {
    log_error("Failed to build sysfs_path.");
    return 0;
  }

  if (!(d = opendir(path))) {
    log_sys_error("opendir", path);
    return 0;
  }

  while (!r && (dirent = readdir(d))) {
    name = dirent->d_name;

    if (!strcmp(name, ".") || !strcmp(name, ".."))
      continue;

    if ((sz = dm_snprintf(path, sizeof(path), "%sblock/%s/dev",
              _sysfs_dir, name)) < 5) {
      log_warn("Couldn't create path for %s.", name);
      continue;
    }

    if (_sysfs_get_dev_major_minor(path, major, minor)) {
      r = dm_strncpy(buf, name, buf_size);
      break; /* found */
    }

    path[sz - 4] = 0; /* strip /dev from end of path string */
    if (stat(path, &st))
      continue;

    if (S_ISDIR(st.st_mode)) {

      /* let's assume there is no tree-complex device in past systems */
      if (!(d_dev = opendir(path))) {
        log_sys_debug("opendir", path);
        continue;
      }

      while ((dirent_dev = readdir(d_dev))) {
        name_dev = dirent_dev->d_name;

        /* skip known ignorable paths */
        if (!strcmp(name_dev, ".") || !strcmp(name_dev, "..") ||
            !strcmp(name_dev, "bdi") ||
            !strcmp(name_dev, "dev") ||
            !strcmp(name_dev, "device") ||
            !strcmp(name_dev, "holders") ||
            !strcmp(name_dev, "integrity") ||
            !strcmp(name_dev, "loop") ||
            !strcmp(name_dev, "queue") ||
            !strcmp(name_dev, "md") ||
            !strcmp(name_dev, "mq") ||
            !strcmp(name_dev, "power") ||
            !strcmp(name_dev, "removable") ||
            !strcmp(name_dev, "slave") ||
            !strcmp(name_dev, "slaves") ||
            !strcmp(name_dev, "subsystem") ||
            !strcmp(name_dev, "trace") ||
            !strcmp(name_dev, "uevent"))
          continue;

        if (dm_snprintf(path, sizeof(path), "%sblock/%s/%s/dev",
            _sysfs_dir, name, name_dev) == -1) {
          log_warn("Couldn't create path for %s/%s.", name, name_dev);
          continue;
        }

        if (_sysfs_get_dev_major_minor(path, major, minor)) {
          r = dm_strncpy(buf, name_dev, buf_size);
          break; /* found */
        }
      }

      if (closedir(d_dev))
        log_sys_debug("closedir", name);
    }
  }

  if (closedir(d))
    log_sys_debug("closedir", path);

  return r;
}

static int _sysfs_get_kernel_name(uint32_t major, uint32_t minor, char *buf, size_t buf_size)
{
  char *name, *sysfs_path, *temp_buf = NULL;
  ssize_t size;
  size_t len;
  int r = 0;

  if (!(sysfs_path = malloc(PATH_MAX)) ||
      !(temp_buf = malloc(PATH_MAX))) {
    log_error("_sysfs_get_kernel_name: failed to allocate temporary buffers");
    goto bad;
  }

  if (dm_snprintf(sysfs_path, PATH_MAX, "%sdev/block/%" PRIu32 ":%" PRIu32,
      _sysfs_dir, major, minor) < 0) {
    log_error("_sysfs_get_kernel_name: dm_snprintf failed");
    goto bad;
  }

  if ((size = readlink(sysfs_path, temp_buf, PATH_MAX - 1)) < 0) {
    if (errno != ENOENT)
      log_sys_error("readlink", sysfs_path);
    else {
      log_sys_debug("readlink", sysfs_path);
      r = _sysfs_find_kernel_name(major, minor, buf, buf_size);
      goto out;
    }
    goto bad;
  }
  temp_buf[size] = '\0';

  if (!(name = strrchr(temp_buf, '/'))) {
    log_error("Could not locate device kernel name in sysfs path %s", temp_buf);
    goto bad;
  }
  name += 1;
  len = size - (name - temp_buf) + 1;

  if (len > buf_size) {
    log_error("_sysfs_get_kernel_name: output buffer too small");
    goto bad;
  }

  strcpy(buf, name);
  r = 1;
bad:
out:
  free(temp_buf);
  free(sysfs_path);

  return r;
}

int dm_device_get_name(uint32_t major, uint32_t minor, int prefer_kernel_name,
           char *buf, size_t buf_size)
{
  if (!*_sysfs_dir)
    return 0;

  /*
   * device-mapper devices and prefer_kernel_name = 0
   * get dm name by reading /sys/dev/block/major:minor/dm/name,
   * fallback to _sysfs_get_kernel_name if not successful
   */
  if (dm_is_dm_major(major) && !prefer_kernel_name) {
    if (_sysfs_get_dm_name(major, minor, buf, buf_size))
      return 1;
    else
      stack;
  }

  /*
   * non-device-mapper devices or prefer_kernel_name = 1
   * get kernel name using readlink /sys/dev/block/major:minor -> .../dm-X
   */
  return _sysfs_get_kernel_name(major, minor, buf, buf_size);
}

int dm_device_has_holders(uint32_t major, uint32_t minor)
{
  char sysfs_path[PATH_MAX];
  struct stat st;

  if (!*_sysfs_dir)
    return 0;

  if (dm_snprintf(sysfs_path, PATH_MAX, "%sdev/block/%" PRIu32
      ":%" PRIu32 "/holders", _sysfs_dir, major, minor) < 0) {
    log_warn("WARNING: sysfs_path dm_snprintf failed.");
    return 0;
  }

  if (stat(sysfs_path, &st)) {
    if (errno != ENOENT)
      log_sys_debug("stat", sysfs_path);
    return 0;
  }

  return !dm_is_empty_dir(sysfs_path);
}

static int _mounted_fs_on_device(const char *kernel_dev_name)
{
  char sysfs_path[PATH_MAX];
  struct dirent *dirent;
  DIR *d;
  struct stat st;
  int r = 0;

  if (dm_snprintf(sysfs_path, PATH_MAX, "%sfs", _sysfs_dir) < 0) {
    log_warn("WARNING: sysfs_path dm_snprintf failed.");
    return 0;
  }

  if (!(d = opendir(sysfs_path))) {
    if (errno != ENOENT)
      log_sys_debug("opendir", sysfs_path);
    return 0;
  }

  while ((dirent = readdir(d))) {
    if (!strcmp(dirent->d_name, ".") || !strcmp(dirent->d_name, ".."))
      continue;

    if (dm_snprintf(sysfs_path, PATH_MAX, "%sfs/%s/%s",
        _sysfs_dir, dirent->d_name, kernel_dev_name) < 0) {
      log_warn("WARNING: sysfs_path dm_snprintf failed.");
      break;
    }

    if (!stat(sysfs_path, &st)) {
      /* found! */
      r = 1;
      break;
    }
    else if (errno != ENOENT) {
      log_sys_debug("stat", sysfs_path);
      break;
    }
  }

  if (closedir(d))
    log_sys_debug("closedir", kernel_dev_name);

  return r;
}

struct mountinfo_s {
  unsigned maj;
  unsigned min;
  int mounted;
};

static int _device_has_mounted_fs(char *buffer, unsigned major, unsigned minor,
          char *target, void *cb_data)
{
  struct mountinfo_s *data = cb_data;
  char kernel_dev_name[PATH_MAX];

  if ((major == data->maj) && (minor == data->min)) {
    if (!dm_device_get_name(major, minor, 1, kernel_dev_name,
          sizeof(kernel_dev_name))) {
      stack;
      *kernel_dev_name = '\0';
    }
    log_verbose("Device %s (%u:%u) appears to be mounted on %s.",
          kernel_dev_name, major, minor, target);
    data->mounted = 1;
  }

  return 1;
}

int dm_device_has_mounted_fs(uint32_t major, uint32_t minor)
{
  char kernel_dev_name[PATH_MAX];
  struct mountinfo_s data = {
    .maj = major,
    .min = minor,
  };

  if (!dm_mountinfo_read(_device_has_mounted_fs, &data))
    stack;

  if (data.mounted)
    return 1;
  /*
   * TODO: Verify dm_mountinfo_read() is superset
   * and remove sysfs check (namespaces)
   */
  /* Get kernel device name first */
  if (!dm_device_get_name(major, minor, 1, kernel_dev_name, PATH_MAX))
    return 0;

  /* Check /sys/fs/<fs_name>/<kernel_dev_name> presence */
  return _mounted_fs_on_device(kernel_dev_name);
}

int dm_mknodes(const char *name)
{
  struct dm_task *dmt;
  int r = 0;

  if (!(dmt = dm_task_create(DM_DEVICE_MKNODES)))
    return_0;

  if (name && !dm_task_set_name(dmt, name))
    goto out;

  if (!dm_task_no_open_count(dmt))
    goto out;

  r = dm_task_run(dmt);

out:
  dm_task_destroy(dmt);
  return r;
}

int dm_driver_version(char *version, size_t size)
{
  struct dm_task *dmt;
  int r = 0;

  if (!(dmt = dm_task_create(DM_DEVICE_VERSION)))
    return_0;

  if (!dm_task_run(dmt))
    log_error("Failed to get driver version");

  if (!dm_task_get_driver_version(dmt, version, size))
    goto out;

  r = 1;

out:
  dm_task_destroy(dmt);
  return r;
}

static void _set_cookie_flags(struct dm_task *dmt, uint16_t flags)
{
  if (!dm_cookie_supported())
    return;

  if (_udev_disabled) {
    /*
     * If udev is disabled, hardcode this functionality:
     *   - we want libdm to create the nodes
     *   - we don't want the /dev/mapper and any subsystem
     *     related content to be created by udev if udev
     *     rules are installed
     */
    flags &= ~DM_UDEV_DISABLE_LIBRARY_FALLBACK;
    flags |= DM_UDEV_DISABLE_DM_RULES_FLAG | DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG;
  }

  dmt->event_nr = flags << DM_UDEV_FLAGS_SHIFT;
}

#ifndef UDEV_SYNC_SUPPORT
void dm_udev_set_sync_support(int sync_with_udev)
{
}

int dm_udev_get_sync_support(void)
{
  return 0;
}

void dm_udev_set_checking(int checking)
{
}

int dm_udev_get_checking(void)
{
  return 0;
}

int dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t flags)
{
  _set_cookie_flags(dmt, flags);

  *cookie = 0;
  dmt->cookie_set = 1;

  return 1;
}

int dm_udev_complete(uint32_t cookie)
{
  return 1;
}

int dm_udev_wait(uint32_t cookie)
{
  update_devs();

  return 1;
}

int dm_udev_wait_immediate(uint32_t cookie, int *ready)
{
  update_devs();
  *ready = 1;

  return 1;
}

#else   /* UDEV_SYNC_SUPPORT */

static int _check_semaphore_is_supported(void)
{
  int maxid;
  union semun arg;
  struct seminfo seminfo;

  arg.__buf = &seminfo;
  maxid = semctl(0, 0, SEM_INFO, arg);

  if (maxid < 0) {
    log_warn("Kernel not configured for semaphores (System V IPC). "
       "Not using udev synchronization code.");
    return 0;
  }

  return 1;
}

static int _check_udev_is_running(void)
{
  struct udev *udev;
  struct udev_queue *udev_queue;
  int r;

  if (!(udev = udev_new()))
    goto_bad;

  if (!(udev_queue = udev_queue_new(udev))) {
    udev_unref(udev);
    goto_bad;
  }

  if (!(r = udev_queue_get_udev_is_active(udev_queue)))
    log_debug_activation("Udev is not running. "
             "Not using udev synchronization code.");

  udev_queue_unref(udev_queue);
  udev_unref(udev);

  return r;

bad:
  log_error("Could not get udev state. Assuming udev is not running.");
  return 0;
}

static void _check_udev_sync_requirements_once(void)
{
  if (_semaphore_supported < 0)
    _semaphore_supported = _check_semaphore_is_supported();

  if (_udev_running < 0) {
    _udev_running = _check_udev_is_running();
    if (_udev_disabled && _udev_running)
      log_warn("Udev is running and DM_DISABLE_UDEV environment variable is set. "
         "Bypassing udev, device-mapper library will manage device "
         "nodes in device directory.");
  }
}

void dm_udev_set_sync_support(int sync_with_udev)
{
  _check_udev_sync_requirements_once();
  _sync_with_udev = sync_with_udev;
}

int dm_udev_get_sync_support(void)
{
  _check_udev_sync_requirements_once();

  return !_udev_disabled && _semaphore_supported &&
    dm_cookie_supported() &&_udev_running && _sync_with_udev;
}

void dm_udev_set_checking(int checking)
{
  if ((_udev_checking = checking))
    log_debug_activation("DM udev checking enabled");
  else
    log_debug_activation("DM udev checking disabled");
}

int dm_udev_get_checking(void)
{
  return _udev_checking;
}

static int _get_cookie_sem(uint32_t cookie, int *semid)
{
  if (cookie >> 16 != DM_COOKIE_MAGIC) {
    log_error("Could not continue to access notification "
        "semaphore identified by cookie value %"
        PRIu32 " (0x%x). Incorrect cookie prefix.",
        cookie, cookie);
    return 0;
  }

  if ((*semid = semget((key_t) cookie, 1, 0)) >= 0)
    return 1;

  switch (errno) {
    case ENOENT:
      log_error("Could not find notification "
          "semaphore identified by cookie "
          "value %" PRIu32 " (0x%x)",
          cookie, cookie);
      break;
    case EACCES:
      log_error("No permission to access "
          "notification semaphore identified "
          "by cookie value %" PRIu32 " (0x%x)",
          cookie, cookie);
      break;
    default:
      log_error("Failed to access notification "
           "semaphore identified by cookie "
           "value %" PRIu32 " (0x%x): %s",
          cookie, cookie, strerror(errno));
      break;
  }

  return 0;
}

static int _udev_notify_sem_inc(uint32_t cookie, int semid)
{
  struct sembuf sb = {0, 1, 0};
  int val;

  if (semop(semid, &sb, 1) < 0) {
    log_error("cookie inc: semid %d: semop failed for cookie 0x%" PRIx32 ": %s",
        semid, cookie, strerror(errno));
    return 0;
  }

  if ((val = semctl(semid, 0, GETVAL)) < 0) {
    log_warn("cookie inc: semid %d: sem_ctl GETVAL failed for "
        "cookie 0x%" PRIx32 ": %s",
        semid, cookie, strerror(errno));
    log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) incremented.",
              cookie, semid);
  } else
    log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) incremented to %d",
             cookie, semid, val);

  return 1;
}

static int _udev_notify_sem_dec(uint32_t cookie, int semid)
{
  struct sembuf sb = {0, -1, IPC_NOWAIT};
  int val;

  if ((val = semctl(semid, 0, GETVAL)) < 0)
    log_warn("cookie dec: semid %d: sem_ctl GETVAL failed for "
       "cookie 0x%" PRIx32 ": %s",
       semid, cookie, strerror(errno));

  if (semop(semid, &sb, 1) < 0) {
    switch (errno) {
      case EAGAIN:
        log_error("cookie dec: semid %d: semop failed for cookie "
            "0x%" PRIx32 ": "
            "incorrect semaphore state",
            semid, cookie);
        break;
      default:
        log_error("cookie dec: semid %d: semop failed for cookie "
            "0x%" PRIx32 ": %s",
            semid, cookie, strerror(errno));
        break;
    }
    return 0;
  }

  if (val < 0)
    log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) decremented.",
             cookie, semid);
  else
    log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) decremented to %d",
             cookie, semid, val - 1);
  return 1;
}

static int _udev_notify_sem_destroy(uint32_t cookie, int semid)
{
  if (semctl(semid, 0, IPC_RMID, 0) < 0) {
    log_error("Could not cleanup notification semaphore "
        "identified by cookie value %" PRIu32 " (0x%x): %s",
        cookie, cookie, strerror(errno));
    return 0;
  }

  log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) destroyed", cookie,
           semid);

  return 1;
}

static int _udev_notify_sem_create(uint32_t *cookie, int *semid)
{
  int fd;
  int gen_semid;
  int val;
  uint16_t base_cookie;
  uint32_t gen_cookie;
  union semun sem_arg;

  if ((fd = open("/dev/urandom", O_RDONLY)) < 0) {
    log_error("Failed to open /dev/urandom "
        "to create random cookie value");
    *cookie = 0;
    return 0;
  }

  /* Generate random cookie value. Be sure it is unique and non-zero. */
  do {
    /* FIXME Handle non-error returns from read(). Move _io() into libdm? */
    if (read(fd, &base_cookie, sizeof(base_cookie)) != sizeof(base_cookie)) {
      log_error("Failed to initialize notification cookie");
      goto bad;
    }

    gen_cookie = DM_COOKIE_MAGIC << 16 | base_cookie;

    if (base_cookie && (gen_semid = semget((key_t) gen_cookie,
            1, 0600 | IPC_CREAT | IPC_EXCL)) < 0) {
      switch (errno) {
        case EEXIST:
          /* if the semaphore key exists, we
           * simply generate another random one */
          base_cookie = 0;
          break;
        case ENOMEM:
          log_error("Not enough memory to create "
              "notification semaphore");
          goto bad;
        case ENOSPC:
          log_error("Limit for the maximum number "
              "of semaphores reached. You can "
              "check and set the limits in "
              "/proc/sys/kernel/sem.");
          goto bad;
        default:
          log_error("Failed to create notification "
              "semaphore: %s", strerror(errno));
          goto bad;
      }
    }
  } while (!base_cookie);

  log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) created",
           gen_cookie, gen_semid);

  sem_arg.val = 1;

  if (semctl(gen_semid, 0, SETVAL, sem_arg) < 0) {
    log_error("cookie create: semid %d: semctl failed: %s", gen_semid, strerror(errno));
    /* We have to destroy just created semaphore
     * so it won't stay in the system. */
    (void) _udev_notify_sem_destroy(gen_cookie, gen_semid);
    goto bad;
  }

  if ((val = semctl(gen_semid, 0, GETVAL)) < 0) {
    log_error("cookie create: semid %d: sem_ctl GETVAL failed for "
        "cookie 0x%" PRIx32 ": %s",
        gen_semid, gen_cookie, strerror(errno));
    (void) _udev_notify_sem_destroy(gen_cookie, gen_semid);
    goto bad;
  }

  log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) incremented to %d",
           gen_cookie, gen_semid, val);

  if (close(fd))
    stack;

  *semid = gen_semid;
  *cookie = gen_cookie;

  return 1;

bad:
  if (close(fd))
    stack;

  *cookie = 0;

  return 0;
}

int dm_udev_create_cookie(uint32_t *cookie)
{
  int semid;

  if (!dm_udev_get_sync_support()) {
    *cookie = 0;
    return 1;
  }

  return _udev_notify_sem_create(cookie, &semid);
}

static const char *_task_type_disp(int type)
{
  switch(type) {
  case DM_DEVICE_CREATE:
    return "CREATE";
        case DM_DEVICE_RELOAD:
    return "RELOAD";
        case DM_DEVICE_REMOVE:
    return "REMOVE";
        case DM_DEVICE_REMOVE_ALL:
    return "REMOVE_ALL";
        case DM_DEVICE_SUSPEND:
    return "SUSPEND";
        case DM_DEVICE_RESUME:
    return "RESUME";
        case DM_DEVICE_INFO:
    return "INFO";
        case DM_DEVICE_DEPS:
    return "DEPS";
        case DM_DEVICE_RENAME:
    return "RENAME";
        case DM_DEVICE_VERSION:
    return "VERSION";
        case DM_DEVICE_STATUS:
    return "STATUS";
        case DM_DEVICE_TABLE:
    return "TABLE";
        case DM_DEVICE_WAITEVENT:
    return "WAITEVENT";
        case DM_DEVICE_LIST:
    return "LIST";
        case DM_DEVICE_CLEAR:
    return "CLEAR";
        case DM_DEVICE_MKNODES:
    return "MKNODES";
        case DM_DEVICE_LIST_VERSIONS:
    return "LIST_VERSIONS";
        case DM_DEVICE_TARGET_MSG:
    return "TARGET_MSG";
        case DM_DEVICE_SET_GEOMETRY:
    return "SET_GEOMETRY";
  }
  return "unknown";
}

int dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t flags)
{
  int semid;

  _set_cookie_flags(dmt, flags);

  if (!dm_udev_get_sync_support()) {
    *cookie = 0;
    dmt->cookie_set = 1;
    return 1;
  }

  if (*cookie) {
    if (!_get_cookie_sem(*cookie, &semid))
      goto_bad;
  } else if (!_udev_notify_sem_create(cookie, &semid))
    goto_bad;

  if (!_udev_notify_sem_inc(*cookie, semid)) {
    log_error("Could not set notification semaphore "
        "identified by cookie value %" PRIu32 " (0x%x)",
        *cookie, *cookie);
    goto bad;
  }

  dmt->event_nr |= ~DM_UDEV_FLAGS_MASK & *cookie;
  dmt->cookie_set = 1;

  log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) assigned to "
           "%s task(%d) with flags%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s (0x%" PRIx16 ")",
           *cookie, semid, _task_type_disp(dmt->type), dmt->type,
           (flags & DM_UDEV_DISABLE_DM_RULES_FLAG) ? " DISABLE_DM_RULES" : "",
           (flags & DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG) ? " DISABLE_SUBSYSTEM_RULES" : "",
           (flags & DM_UDEV_DISABLE_DISK_RULES_FLAG) ? " DISABLE_DISK_RULES" : "",
           (flags & DM_UDEV_DISABLE_OTHER_RULES_FLAG) ? " DISABLE_OTHER_RULES" : "",
           (flags & DM_UDEV_LOW_PRIORITY_FLAG) ? " LOW_PRIORITY" : "",
           (flags & DM_UDEV_DISABLE_LIBRARY_FALLBACK) ? " DISABLE_LIBRARY_FALLBACK" : "",
           (flags & DM_UDEV_PRIMARY_SOURCE_FLAG) ? " PRIMARY_SOURCE" : "",
           (flags & DM_SUBSYSTEM_UDEV_FLAG0) ? " SUBSYSTEM_0" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG1) ? " SUBSYSTEM_1" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG2) ? " SUBSYSTEM_2" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG3) ? " SUBSYSTEM_3" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG4) ? " SUBSYSTEM_4" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG5) ? " SUBSYSTEM_5" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG6) ? " SUBSYSTEM_6" : " ",
           (flags & DM_SUBSYSTEM_UDEV_FLAG7) ? " SUBSYSTEM_7" : " ",
           flags);

  return 1;

bad:
  dmt->event_nr = 0;
  return 0;
}

int dm_udev_complete(uint32_t cookie)
{
  int semid;

  if (!cookie || !dm_udev_get_sync_support())
    return 1;

  if (!_get_cookie_sem(cookie, &semid))
    return_0;

  if (!_udev_notify_sem_dec(cookie, semid)) {
    log_error("Could not signal waiting process using notification "
        "semaphore identified by cookie value %" PRIu32 " (0x%x)",
        cookie, cookie);
    return 0;
  }

  return 1;
}

/*
 * If *nowait is set, return immediately leaving it set if the semaphore
 * is not ready to be decremented to 0.  *nowait is cleared if the wait
 * succeeds.
 */
static int _udev_wait(uint32_t cookie, int *nowait)
{
  int semid;
  struct sembuf sb = {0, 0, 0};
  int val;

  if (!cookie || !dm_udev_get_sync_support())
    return 1;

  if (!_get_cookie_sem(cookie, &semid))
    return_0;

  /* Return immediately if the semaphore value exceeds 1? */
  if (*nowait) {
    if ((val = semctl(semid, 0, GETVAL)) < 0) {
      log_error("semid %d: sem_ctl GETVAL failed for "
          "cookie 0x%" PRIx32 ": %s",
          semid, cookie, strerror(errno));
      return 0;   
    }

    if (val > 1)
      return 1;

    *nowait = 0;
  }

  if (!_udev_notify_sem_dec(cookie, semid)) {
    log_error("Failed to set a proper state for notification "
        "semaphore identified by cookie value %" PRIu32 " (0x%x) "
        "to initialize waiting for incoming notifications.",
        cookie, cookie);
    (void) _udev_notify_sem_destroy(cookie, semid);
    return 0;
  }

  log_debug_activation("Udev cookie 0x%" PRIx32 " (semid %d) waiting for zero",
           cookie, semid);

repeat_wait:
  if (semop(semid, &sb, 1) < 0) {
    if (errno == EINTR)
      goto repeat_wait;
    else if (errno == EIDRM)
      return 1;

    log_error("Could not set wait state for notification semaphore "
        "identified by cookie value %" PRIu32 " (0x%x): %s",
        cookie, cookie, strerror(errno));
    (void) _udev_notify_sem_destroy(cookie, semid);
    return 0;
  }

  return _udev_notify_sem_destroy(cookie, semid);
}

int dm_udev_wait(uint32_t cookie)
{
  int nowait = 0;
  int r = _udev_wait(cookie, &nowait);

  update_devs();

  return r;
}

int dm_udev_wait_immediate(uint32_t cookie, int *ready)
{
  int nowait = 1;
  int r = _udev_wait(cookie, &nowait);

  if (r && nowait) {
    *ready = 0;
    return 1;
  }

  update_devs();
  *ready = 1;

  return r;
}
#endif    /* UDEV_SYNC_SUPPORT */

Coverage Report

Created: 2026-02-22 06:10