Re: [PATCH] use uevents in udevd

[Hannes Reinecke <hare@suse.de>]

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Marco d'Itri wrote:
> On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> 
> 
>>Comments welcome.
> 
> Nice work.
> How can the init scripts determine if support for uevents is available?
> 
Good question. Asked myself the same one just now.
I couldn't figure out whether this information is exported from the 
kernel directly, so that leaves two possibilities:

- check /proc/config.gz for CONFIG_KOBJECT_UEVENT
   (if /proc/config.gz is available)
- use a program to check for it (like the attached one).

HTH,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

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/*
 * uevent_check.c - check for uevent socket
 *
 * based on uevent_listen.c
 *
 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
 * Copyright (C) 2004 Hannes Reinecke <hare@suse.de>
 *
 *	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.,
 *	675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/socket.h>
#include <sys/user.h>
#include <asm/types.h>
#include <linux/netlink.h>

int main(int argc, char *argv[])
{
	int sock;
	struct sockaddr_nl snl;
	int retval;

	if (getuid() != 0) {
		fprintf(stderr,"need to be root, exit\n");
		exit(0);
	}

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

	sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
	if (sock == -1) {
		fprintf(stderr,"error getting socket, exit\n");
		exit(1);
	}

	retval = bind(sock, (struct sockaddr *) &snl,
		      sizeof(struct sockaddr_nl));
	if (retval < 0) {
		fprintf("bind failed, exit\n");
		exit(1);
	}
	fprintf(stderr,"uevent socket available");
	exit(0);
}