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/*
* sysfs based topology -- gathers topology information from Linux sysfs
*
* Copyright (C) 2009 Karel Zak <kzak@redhat.com>
*
* This file may be redistributed under the terms of the
* GNU Lesser General Public License.
*
* For more information see Linux kernel Documentation/ABI/testing/sysfs-block.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include "sysfs.h"
#include "topology.h"
/*
* Sysfs topology values (since 2.6.31, May 2009).
*/
static struct topology_val {
/* /sys/dev/block/<maj>:<min>/<ATTR> */
const char *attr;
/* functions to set probing result */
int (*set_ulong)(blkid_probe, unsigned long);
int (*set_int)(blkid_probe, int);
} topology_vals[] = {
{ "alignment_offset", NULL, blkid_topology_set_alignment_offset },
{ "queue/minimum_io_size", blkid_topology_set_minimum_io_size },
{ "queue/optimal_io_size", blkid_topology_set_optimal_io_size },
{ "queue/physical_block_size", blkid_topology_set_physical_sector_size },
};
static int probe_sysfs_tp(blkid_probe pr,
const struct blkid_idmag *mag __attribute__((__unused__)))
{
dev_t dev;
int rc, set_parent = 1;
struct path_cxt *pc;
size_t i, count = 0;
dev = blkid_probe_get_devno(pr);
if (!dev)
return 1;
pc = ul_new_sysfs_path(dev, NULL, NULL);
if (!pc)
return 1;
rc = 1; /* nothing (default) */
for (i = 0; i < ARRAY_SIZE(topology_vals); i++) {
struct topology_val *val = &topology_vals[i];
int ok = ul_path_access(pc, F_OK, val->attr) == 0;
rc = 1; /* nothing */
if (!ok && set_parent) {
dev_t disk = blkid_probe_get_wholedisk_devno(pr);
set_parent = 0;
/*
* Read attributes from "disk" if the current device is
* a partition. Note that sysfs ul_path_* API is able
* to redirect requests to attributes if parent is set.
*/
if (disk && disk != dev) {
struct path_cxt *parent = ul_new_sysfs_path(disk, NULL, NULL);
if (!parent)
goto done;
sysfs_blkdev_set_parent(pc, parent);
ul_unref_path(parent);
/* try it again */
ok = ul_path_access(pc, F_OK, val->attr) == 0;
}
}
if (!ok)
continue; /* attribute does not exist */
if (val->set_ulong) {
uint64_t data;
if (ul_path_read_u64(pc, &data, val->attr) != 0)
continue;
rc = val->set_ulong(pr, (unsigned long) data);
} else if (val->set_int) {
int64_t data;
if (ul_path_read_s64(pc, &data, val->attr) != 0)
continue;
rc = val->set_int(pr, (int) data);
}
if (rc < 0)
goto done; /* error */
if (rc == 0)
count++;
}
done:
ul_unref_path(pc); /* unref pc and parent */
if (count)
return 0; /* success */
return rc; /* error or nothing */
}
const struct blkid_idinfo sysfs_tp_idinfo =
{
.name = "sysfs",
.probefunc = probe_sysfs_tp,
.magics = BLKID_NONE_MAGIC
};
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