systemd/udevmonitor.c

/*
 * Copyright (C) 2004-2006 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 version 2 of the License.
 * 
 *	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.,
 *	51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#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 <sys/time.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/select.h>
#include <linux/types.h>
#include <linux/netlink.h>

#include "udev.h"
#include "udevd.h"

static int uevent_netlink_sock = -1;
static int udev_monitor_sock = -1;
static volatile int udev_exit;

static int init_udev_monitor_socket(void)
{
	struct sockaddr_un saddr;
	socklen_t addrlen;
	const int feature_on = 1;
	int retval;

	memset(&saddr, 0x00, sizeof(saddr));
	saddr.sun_family = AF_LOCAL;
	/* use abstract namespace for socket path */
	strcpy(&saddr.sun_path[1], "/org/kernel/udev/monitor");
	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;

	udev_monitor_sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
	if (udev_monitor_sock == -1) {
		fprintf(stderr, "error getting socket: %s\n", strerror(errno));
		return -1;
	}

	/* the bind takes care of ensuring only one copy running */
	retval = bind(udev_monitor_sock, (struct sockaddr *) &saddr, addrlen);
	if (retval < 0) {
		fprintf(stderr, "bind failed: %s\n", strerror(errno));
		close(udev_monitor_sock);
		udev_monitor_sock = -1;
		return -1;
	}

	/* enable receiving of the sender credentials */
	setsockopt(udev_monitor_sock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));

	return 0;
}

static int init_uevent_netlink_sock(void)
{
	struct sockaddr_nl snl;
	int retval;

	memset(&snl, 0x00, sizeof(struct sockaddr_nl));
	snl.nl_family = AF_NETLINK;
	snl.nl_pid = getpid();
	snl.nl_groups = 1;

	uevent_netlink_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
	if (uevent_netlink_sock == -1) {
		fprintf(stderr, "error getting socket: %s\n", strerror(errno));
		return -1;
	}

	retval = bind(uevent_netlink_sock, (struct sockaddr *) &snl,
		      sizeof(struct sockaddr_nl));
	if (retval < 0) {
		fprintf(stderr, "bind failed: %s\n", strerror(errno));
		close(uevent_netlink_sock);
		uevent_netlink_sock = -1;
		return -1;
	}

	return 0;
}

static void asmlinkage sig_handler(int signum)
{
	if (signum == SIGINT || signum == SIGTERM)
		udev_exit = 1;
}

int main(int argc, char *argv[])
{
	struct sigaction act;
	int env = 0;
	fd_set readfds;
	int i;
	int retval = 0;

	for (i = 1 ; i < argc; i++) {
		char *arg = argv[i];
		if (strcmp(arg, "--env") == 0 || strcmp(arg, "-e") == 0)
			env = 1;
		else if (strcmp(arg, "--help") == 0  || strcmp(arg, "-h") == 0){
			printf("Usage: udevmonitor [--help] [--env]\n"
				"  --env    print the whole event environment\n"
				"  --help   print this help text\n\n");
			exit(0);
		} else {
			fprintf(stderr, "unrecognized option '%s'\n", arg);
			exit(1);
		}
	}

	if (getuid() != 0) {
		fprintf(stderr, "root privileges required\n");
		exit(2);
	}

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

	retval = init_udev_monitor_socket();
	if (retval)
		goto out;

	retval = init_uevent_netlink_sock();
	if (retval)
		goto out;

	printf("udevmonitor prints the received event from the kernel [UEVENT]\n"
	       "and the event which udev sends out after rule processing [UDEV]\n\n");

	while (!udev_exit) {
		char buf[UEVENT_BUFFER_SIZE*2];
		ssize_t buflen;
		int fdcount;
		struct timeval tv;
		struct timezone tz;
		char timestr[64];

		buflen = 0;
		FD_ZERO(&readfds);
		if (uevent_netlink_sock >= 0)
			FD_SET(uevent_netlink_sock, &readfds);
		if (udev_monitor_sock >= 0)
			FD_SET(udev_monitor_sock, &readfds);

		fdcount = select(UDEV_MAX(uevent_netlink_sock, udev_monitor_sock)+1, &readfds, NULL, NULL, NULL);
		if (fdcount < 0) {
			if (errno != EINTR)
				fprintf(stderr, "error receiving uevent message: %s\n", strerror(errno));
			continue;
		}

		if (gettimeofday(&tv, &tz) == 0) {
			snprintf(timestr, sizeof(timestr), "%llu.%06u",
				 (unsigned long long) tv.tv_sec, (unsigned int) tv.tv_usec);
		} else
			timestr[0] = '\0';

		if ((uevent_netlink_sock >= 0) && FD_ISSET(uevent_netlink_sock, &readfds)) {
			buflen = recv(uevent_netlink_sock, &buf, sizeof(buf), 0);
			if (buflen <=  0) {
				fprintf(stderr, "error receiving uevent message: %s\n", strerror(errno));
				continue;
			}
			printf("UEVENT[%s] %s\n", timestr, buf);
		}

		if ((udev_monitor_sock >= 0) && FD_ISSET(udev_monitor_sock, &readfds)) {
			buflen = recv(udev_monitor_sock, &buf, sizeof(buf), 0);
			if (buflen <=  0) {
				fprintf(stderr, "error receiving udev message: %s\n", strerror(errno));
				continue;
			}
			printf("UDEV  [%s] %s\n", timestr, buf);
		}

		if (buflen == 0)
			continue;

		/* print environment */
		if (env) {
			size_t bufpos;

			/* start of payload */
			bufpos = strlen(buf) + 1;

			while (bufpos < (size_t)buflen) {
				int keylen;
				char *key;

				key = &buf[bufpos];
				keylen = strlen(key);
				if (keylen == 0)
					break;
				printf("%s\n", key);
				bufpos += keylen + 1;
			}
			printf("\n");
		}
	}

out:
	if (uevent_netlink_sock >= 0)
		close(uevent_netlink_sock);
	if (udev_monitor_sock >= 0)
		close(udev_monitor_sock);

	if (retval)
		return 3;
	return 0;
}