Le 29/06/2017 à 15:15, Didier Kryn a écrit :
Please find it in attachment. The archive contains four files:
README
etc/init.d/mdev -- The start/stop script for Sysvinit
etc/mdev.conf -- The necessary configuration file for mdev
sbin/mdev-disk -- An experimental script to manage /dev/disk/by-label
-- and /dev/disk/by-uuid
I might restart experimenting with it some day...
Hmm, something similar could be used to create thoose /dev/disk/by-*,
for a static /dev:
find /dev -type b | xargs blkid | sort |
some_script_to_populate_by_xxx
But if that is only a transformed /sys/class/block, wouldn't it be
easier if there was a /sys/class/uuid or similar ?
Also man blkid says:
# man blkid | grep -A6 ' -L label$'
-L label
Look up the device that uses this label (equal to: -l
-o device
-t LABEL=<label>). This lookup method is able to
reliably use
/dev/disk/by-label udev symlinks (dependent on a
setting in
/etc/blkid.conf). Avoid using the symlinks directly;
it is not
reliable to use the symlinks without
verification. The -L
option works on systems with and without udev.
so if /dev/disk/by-* isn't reliable, why do we have them ?
Regards,
/Karl Hammar
Everybody is using blkid to build thiese links, my script as well
as Udev and Vdev. You probably noticed that blkid has a special option
for Udev because Udev people are too lazzy to parse the response. In
Vdev, Jude made the parsing job to be compatible with Busybox's blkid
which hasn't this special format.
So blkid authors on one hand provide a special format for Udev to
create the symlinks, and on the other hand claim that they aren't
reliable!
For people wanting to give a look at what's going through the
uevent netlink, here is a small C program to dump it:
/* Print uevents from netlink -- Author: Didier Kryn <[email protected]> */
/* With command-line argument "-noudev", skip events from libudev */
#include <asm/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#define BUFSIZE 4096
int main( int argc, char **argv )
{
char b[BUFSIZE];
struct sockaddr_nl nladdr;
int ns, len, i, noudev;
char *c, *max;
/*-------------- check option to skip libudev events --------------*/
noudev = 0;
if(argc>1)
{
if(!strcmp(argv[1], "-noudev")) noudev =1;
else fprintf(stderr, "nluevent: ignore unknown argument %s\n",
argv[1]);
}
/*---------------- create and open netlink socket -----------------*/
ns = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
if( ns == -1 ) goto error;
len = sizeof(b);
/* set socket receive buffer size to the size of our own buffer */
if(geteuid()) i = setsockopt(ns, SOL_SOCKET, SO_RCVBUF, &len,
sizeof(len));
else i = setsockopt(ns, SOL_SOCKET, SO_RCVBUFFORCE, &len, sizeof(len));
if( i< 0) goto error;
/* set socket address */
memset(&nladdr, 0, sizeof(struct sockaddr_nl));
nladdr.nl_family = AF_NETLINK;
nladdr.nl_pid = getpid();
nladdr.nl_groups = -1;
/* bind */
if ( bind(ns, (void *)&nladdr, sizeof(struct sockaddr_nl)) )
goto error;
/*------------------ receive and print forever ------------------*/
while(1)
{
len = recv ( ns, &b, sizeof(b), MSG_TRUNC );
if(len == -1) break;
else if(len > sizeof(b))
{
fprintf(stderr, "Netlink message exceeded buffer size by %d chars. "
"Message truncated.\n", len - sizeof(b) );
len = sizeof(b);
}
if(noudev && !strncmp("libudev", b,7)) continue; /* skip libudev
event */
max=b+len;
/* uevent datagrams contain several strings separated by nulls */
for( c=b; c<max; c++ ) { if(!*c) *c='\n'; } /* replace \0 with \n */
fputs(b, stdout);
}
/*------------------------- exceptions --------------------------*/
error:
perror("nluevent");
return 1;
}
_______________________________________________
Dng mailing list
[email protected]
https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
