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/*
* mdadm - manage Linux "md" devices aka RAID arrays.
*
* Copyright (C) 2022 Mateusz Grzonka <mateusz.grzonka@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "mdadm.h"
#include "udev.h"
#include "md_p.h"
#include "md_u.h"
#include <sys/wait.h>
#include <signal.h>
#include <limits.h>
#include <syslog.h>
#include <libudev.h>
/*
* udev_is_available() - Checks for udev in the system.
*
* Function looks whether udev directories are available and MDADM_NO_UDEV env defined.
*
* Return:
* true if udev is available,
* false if not
*/
bool udev_is_available(void)
{
struct stat stb;
if (stat("/dev/.udev", &stb) != 0 &&
stat("/run/udev", &stb) != 0)
return false;
if (check_env("MDADM_NO_UDEV") == 1)
return false;
return true;
}
#ifndef NO_LIBUDEV
static struct udev *udev;
static struct udev_monitor *udev_monitor;
/*
* udev_release() - Drops references of udev and udev_monitor.
*/
static void udev_release(void)
{
udev_monitor_unref(udev_monitor);
udev_unref(udev);
}
/*
* udev_initialize() - Initializes udev and udev_monitor structures.
*
* Function initializes udev, udev_monitor, and sets udev_monitor filter for block devices.
*
* Return:
* UDEV_STATUS_SUCCESS on success
* UDEV_STATUS_ERROR on error
* UDEV_STATUS_ERROR_NO_UDEV when udev not available
*/
static enum udev_status udev_initialize(void)
{
if (!udev_is_available()) {
pr_err("No udev.\n");
return UDEV_STATUS_ERROR_NO_UDEV;
}
udev = udev_new();
if (!udev) {
pr_err("Cannot initialize udev.\n");
return UDEV_STATUS_ERROR;
}
udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
if (!udev_monitor) {
pr_err("Cannot initialize udev monitor.\n");
udev = udev_unref(udev);
return UDEV_STATUS_ERROR;
}
if (udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "block", 0) < 0) {
pr_err("Cannot add udev monitor event filter for md devices.\n");
udev_release();
return UDEV_STATUS_ERROR;
}
if (udev_monitor_enable_receiving(udev_monitor) < 0) {
pr_err("Cannot enable receiving udev events through udev monitor.\n");
udev_release();
return UDEV_STATUS_ERROR;
}
atexit(udev_release);
return UDEV_STATUS_SUCCESS;
}
/*
* udev_wait_for_events() - Waits for events from udev.
* @seconds: Timeout in seconds.
*
* Function waits udev events, wakes up on event or timeout.
*
* Return:
* UDEV_STATUS_SUCCESS on detected event
* UDEV_STATUS_TIMEOUT on timeout
* UDEV_STATUS_ERROR on error
*/
enum udev_status udev_wait_for_events(int seconds)
{
int fd;
fd_set readfds;
struct timeval tv;
int ret;
if (!udev || !udev_monitor) {
ret = udev_initialize();
if (ret != UDEV_STATUS_SUCCESS)
return ret;
}
fd = udev_monitor_get_fd(udev_monitor);
if (fd < 0) {
pr_err("Cannot access file descriptor associated with udev monitor.\n");
return UDEV_STATUS_ERROR;
}
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
tv.tv_sec = seconds;
tv.tv_usec = 0;
if (select(fd + 1, &readfds, NULL, NULL, &tv) > 0 && FD_ISSET(fd, &readfds))
if (udev_monitor_receive_device(udev_monitor))
return UDEV_STATUS_SUCCESS; /* event detected */
return UDEV_STATUS_TIMEOUT;
}
#endif
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