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util-linux/libblkid/src/topology/dm.c

136 lines
2.8 KiB

/*
* device-mapper (dm) topology
* -- this is fallback for old systems where the topology information is not
* exported by sysfs
*
* Copyright (C) 2009 Karel Zak <kzak@redhat.com>
*
* This file may be redistributed under the terms of the
* GNU Lesser General Public License.
*
*/
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "topology.h"
static int is_dm_device(dev_t devno)
{
return blkid_driver_has_major("device-mapper", major(devno));
}
static int probe_dm_tp(blkid_probe pr,
const struct blkid_idmag *mag __attribute__((__unused__)))
{
const char *paths[] = {
"/usr/local/sbin/dmsetup",
"/usr/sbin/dmsetup",
"/sbin/dmsetup"
};
int dmpipe[] = { -1, -1 }, stripes, stripesize;
const char *cmd = NULL;
FILE *stream = NULL;
long long offset, size;
size_t i;
dev_t devno = blkid_probe_get_devno(pr);
if (!devno)
goto nothing; /* probably not a block device */
if (!is_dm_device(devno))
goto nothing;
for (i = 0; i < ARRAY_SIZE(paths); i++) {
struct stat sb;
if (stat(paths[i], &sb) == 0) {
cmd = paths[i];
break;
}
}
if (!cmd)
goto nothing;
if (pipe(dmpipe) < 0) {
DBG(LOWPROBE, ul_debug("Failed to open pipe: errno=%d", errno));
goto nothing;
}
switch (fork()) {
case 0:
{
const char *dmargv[7];
char maj[16], min[16];
/* Plumbing */
close(dmpipe[0]);
if (dmpipe[1] != STDOUT_FILENO)
dup2(dmpipe[1], STDOUT_FILENO);
/* The libblkid library could linked with setuid programs */
if (setgid(getgid()) < 0)
exit(1);
if (setuid(getuid()) < 0)
exit(1);
snprintf(maj, sizeof(maj), "%d", major(devno));
snprintf(min, sizeof(min), "%d", minor(devno));
dmargv[0] = cmd;
dmargv[1] = "table";
dmargv[2] = "-j";
dmargv[3] = maj;
dmargv[4] = "-m";
dmargv[5] = min;
dmargv[6] = NULL;
execv(dmargv[0], (char * const *) dmargv);
DBG(LOWPROBE, ul_debug("Failed to execute %s: errno=%d", cmd, errno));
exit(1);
}
case -1:
DBG(LOWPROBE, ul_debug("Failed to forking: errno=%d", errno));
goto nothing;
default:
break;
}
stream = fdopen(dmpipe[0], "r" UL_CLOEXECSTR);
if (!stream)
goto nothing;
if (fscanf(stream, "%lld %lld striped %d %d ",
&offset, &size, &stripes, &stripesize) != 0)
goto nothing;
blkid_topology_set_minimum_io_size(pr, stripesize << 9);
blkid_topology_set_optimal_io_size(pr, (stripes * stripesize) << 9);
fclose(stream);
close(dmpipe[1]);
return 0;
nothing:
if (stream)
fclose(stream);
else if (dmpipe[0] != -1)
close(dmpipe[0]);
if (dmpipe[1] != -1)
close(dmpipe[1]);
return 1;
}
const struct blkid_idinfo dm_tp_idinfo =
{
.name = "dm",
.probefunc = probe_dm_tp,
.magics = BLKID_NONE_MAGIC
};