systemd/udev/udevadm-monitor.c

/*
 * Copyright (C) 2004-2010 Kay Sievers <kay.sievers@vrfy.org>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <getopt.h>
#include <time.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/epoll.h>
#include <linux/types.h>
#include <linux/netlink.h>

#include "udev.h"

static bool udev_exit;

static void sig_handler(int signum)
{
	if (signum == SIGINT || signum == SIGTERM)
		udev_exit = true;
}

static void print_device(struct udev_device *device, const char *source, int prop)
{
	struct timespec ts;

	clock_gettime(CLOCK_MONOTONIC, &ts);
	printf("%-6s[%llu.%06u] %-8s %s (%s)\n",
	       source,
	       (unsigned long long) ts.tv_sec, (unsigned int) ts.tv_nsec/1000,
	       udev_device_get_action(device),
	       udev_device_get_devpath(device),
	       udev_device_get_subsystem(device));
	if (prop) {
		struct udev_list_entry *list_entry;

		udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(device))
			printf("%s=%s\n",
			       udev_list_entry_get_name(list_entry),
			       udev_list_entry_get_value(list_entry));
		printf("\n");
	}
}

static int adm_monitor(struct udev *udev, int argc, char *argv[])
{
	struct sigaction act;
	sigset_t mask;
	int option;
	bool prop = false;
	bool print_kernel = false;
	bool print_udev = false;
	struct udev_list subsystem_match_list;
	struct udev_list tag_match_list;
	struct udev_monitor *udev_monitor = NULL;
	struct udev_monitor *kernel_monitor = NULL;
	int fd_ep = -1;
	int fd_kernel = -1, fd_udev = -1;
	struct epoll_event ep_kernel, ep_udev;
	int rc = 0;

	static const struct option options[] = {
		{ "property", no_argument, NULL, 'p' },
		{ "environment", no_argument, NULL, 'e' },
		{ "kernel", no_argument, NULL, 'k' },
		{ "udev", no_argument, NULL, 'u' },
		{ "subsystem-match", required_argument, NULL, 's' },
		{ "tag-match", required_argument, NULL, 't' },
		{ "help", no_argument, NULL, 'h' },
		{}
	};

	udev_list_init(udev, &subsystem_match_list, true);
	udev_list_init(udev, &tag_match_list, true);

	for (;;) {
		option = getopt_long(argc, argv, "pekus:t:h", options, NULL);
		if (option == -1)
			break;

		switch (option) {
		case 'p':
		case 'e':
			prop = true;
			break;
		case 'k':
			print_kernel = true;
			break;
		case 'u':
			print_udev = true;
			break;
		case 's':
			{
				char subsys[UTIL_NAME_SIZE];
				char *devtype;

				util_strscpy(subsys, sizeof(subsys), optarg);
				devtype = strchr(subsys, '/');
				if (devtype != NULL) {
					devtype[0] = '\0';
					devtype++;
				}
				udev_list_entry_add(&subsystem_match_list, subsys, devtype);
				break;
			}
		case 't':
			udev_list_entry_add(&tag_match_list, optarg, NULL);
			break;
		case 'h':
			printf("Usage: udevadm monitor [--property] [--kernel] [--udev] [--help]\n"
			       "  --property                              print the event properties\n"
			       "  --kernel                                print kernel uevents\n"
			       "  --udev                                  print udev events\n"
			       "  --subsystem-match=<subsystem[/devtype]> filter events by subsystem\n"
			       "  --tag-match=<tag>                       filter events by tag\n"
			       "  --help\n\n");
			goto out;
		default:
			rc = 1;
			goto out;
		}
	}

	if (!print_kernel && !print_udev) {
		print_kernel = true;
		print_udev = true;
	}

	/* set signal handlers */
	memset(&act, 0x00, sizeof(struct sigaction));
	act.sa_handler = sig_handler;
	sigemptyset(&act.sa_mask);
	act.sa_flags = SA_RESTART;
	sigaction(SIGINT, &act, NULL);
	sigaction(SIGTERM, &act, NULL);
	sigemptyset(&mask);
	sigaddset(&mask, SIGINT);
	sigaddset(&mask, SIGTERM);
	sigprocmask(SIG_UNBLOCK, &mask, NULL);

	fd_ep = epoll_create1(EPOLL_CLOEXEC);
	if (fd_ep < 0) {
		err(udev, "error creating epoll fd: %m\n");
		goto out;
	}

	printf("monitor will print the received events for:\n");
	if (print_udev) {
		struct udev_list_entry *entry;

		udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
		if (udev_monitor == NULL) {
			fprintf(stderr, "error: unable to create netlink socket\n");
			rc = 1;
			goto out;
		}
		udev_monitor_set_receive_buffer_size(udev_monitor, 128*1024*1024);
		fd_udev = udev_monitor_get_fd(udev_monitor);

		udev_list_entry_foreach(entry, udev_list_get_entry(&subsystem_match_list)) {
			const char *subsys = udev_list_entry_get_name(entry);
			const char *devtype = udev_list_entry_get_value(entry);

			if (udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, subsys, devtype) < 0)
				fprintf(stderr, "error: unable to apply subsystem filter '%s'\n", subsys);
		}

		udev_list_entry_foreach(entry, udev_list_get_entry(&tag_match_list)) {
			const char *tag = udev_list_entry_get_name(entry);

			if (udev_monitor_filter_add_match_tag(udev_monitor, tag) < 0)
				fprintf(stderr, "error: unable to apply tag filter '%s'\n", tag);
		}

		if (udev_monitor_enable_receiving(udev_monitor) < 0) {
			fprintf(stderr, "error: unable to subscribe to udev events\n");
			rc = 2;
			goto out;
		}

		memset(&ep_udev, 0, sizeof(struct epoll_event));
		ep_udev.events = EPOLLIN;
		ep_udev.data.fd = fd_udev;
		if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_udev, &ep_udev) < 0) {
			err(udev, "fail to add fd to epoll: %m\n");
			goto out;
		}

		printf("UDEV - the event which udev sends out after rule processing\n");
	}

	if (print_kernel) {
		struct udev_list_entry *entry;

		kernel_monitor = udev_monitor_new_from_netlink(udev, "kernel");
		if (kernel_monitor == NULL) {
			fprintf(stderr, "error: unable to create netlink socket\n");
			rc = 3;
			goto out;
		}
		udev_monitor_set_receive_buffer_size(kernel_monitor, 128*1024*1024);
		fd_kernel = udev_monitor_get_fd(kernel_monitor);

		udev_list_entry_foreach(entry, udev_list_get_entry(&subsystem_match_list)) {
			const char *subsys = udev_list_entry_get_name(entry);

			if (udev_monitor_filter_add_match_subsystem_devtype(kernel_monitor, subsys, NULL) < 0)
				fprintf(stderr, "error: unable to apply subsystem filter '%s'\n", subsys);
		}

		if (udev_monitor_enable_receiving(kernel_monitor) < 0) {
			fprintf(stderr, "error: unable to subscribe to kernel events\n");
			rc = 4;
			goto out;
		}

		memset(&ep_kernel, 0, sizeof(struct epoll_event));
		ep_kernel.events = EPOLLIN;
		ep_kernel.data.fd = fd_kernel;
		if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_kernel, &ep_kernel) < 0) {
			err(udev, "fail to add fd to epoll: %m\n");
			goto out;
		}

		printf("KERNEL - the kernel uevent\n");
	}
	printf("\n");

	while (!udev_exit) {
		int fdcount;
		struct epoll_event ev[4];
		int i;

		fdcount = epoll_wait(fd_ep, ev, ARRAY_SIZE(ev), -1);
		if (fdcount < 0) {
			if (errno != EINTR)
				fprintf(stderr, "error receiving uevent message: %m\n");
			continue;
		}

		for (i = 0; i < fdcount; i++) {
			if (ev[i].data.fd == fd_kernel && ev[i].events & EPOLLIN) {
				struct udev_device *device;

				device = udev_monitor_receive_device(kernel_monitor);
				if (device == NULL)
					continue;
				print_device(device, "KERNEL", prop);
				udev_device_unref(device);
			} else if (ev[i].data.fd == fd_udev && ev[i].events & EPOLLIN) {
				struct udev_device *device;

				device = udev_monitor_receive_device(udev_monitor);
				if (device == NULL)
					continue;
				print_device(device, "UDEV", prop);
				udev_device_unref(device);
			}
		}
	}
out:
	if (fd_ep >= 0)
		close(fd_ep);
	udev_monitor_unref(udev_monitor);
	udev_monitor_unref(kernel_monitor);
	udev_list_cleanup(&subsystem_match_list);
	udev_list_cleanup(&tag_match_list);
	return rc;
}

const struct udevadm_cmd udevadm_monitor = {
	.name = "monitor",
	.cmd = adm_monitor,
	.help = "listen to kernel and udev events",
};