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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
Copyright 2010 Lennart Poettering
***/
#include <sys/stat.h>
#include <sys/statfs.h>
#include "alloc-util.h"
#include "blockdev-util.h"
#include "btrfs-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "missing.h"
#include "stat-util.h"
int block_get_whole_disk(dev_t d, dev_t *ret) {
char p[SYS_BLOCK_PATH_MAX("/partition")];
_cleanup_free_ char *s = NULL;
unsigned n, m;
int r;
assert(ret);
/* If it has a queue this is good enough for us */
xsprintf_sys_block_path(p, "/queue", d);
if (access(p, F_OK) >= 0) {
*ret = d;
return 0;
}
/* If it is a partition find the originating device */
xsprintf_sys_block_path(p, "/partition", d);
if (access(p, F_OK) < 0)
return -ENOENT;
/* Get parent dev_t */
xsprintf_sys_block_path(p, "/../dev", d);
r = read_one_line_file(p, &s);
if (r < 0)
return r;
r = sscanf(s, "%u:%u", &m, &n);
if (r != 2)
return -EINVAL;
/* Only return this if it is really good enough for us. */
xsprintf_sys_block_path(p, "/queue", makedev(m, n));
if (access(p, F_OK) < 0)
return -ENOENT;
*ret = makedev(m, n);
return 0;
}
int get_block_device(const char *path, dev_t *dev) {
struct stat st;
struct statfs sfs;
assert(path);
assert(dev);
/* Get's the block device directly backing a file system. If
* the block device is encrypted, returns the device mapper
* block device. */
if (lstat(path, &st))
return -errno;
if (major(st.st_dev) != 0) {
*dev = st.st_dev;
return 1;
}
if (statfs(path, &sfs) < 0)
return -errno;
if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
return btrfs_get_block_device(path, dev);
*dev = 0;
return 0;
}
int block_get_originating(dev_t dt, dev_t *ret) {
_cleanup_closedir_ DIR *d = NULL;
_cleanup_free_ char *t = NULL;
char p[SYS_BLOCK_PATH_MAX("/slaves")];
struct dirent *de, *found = NULL;
unsigned maj, min;
const char *q;
int r;
/* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
* trying to find the next underlying layer. */
xsprintf_sys_block_path(p, "/slaves", dt);
d = opendir(p);
if (!d)
return -errno;
FOREACH_DIRENT_ALL(de, d, return -errno) {
if (dot_or_dot_dot(de->d_name))
continue;
if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
continue;
if (found) {
_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
/* We found a device backed by multiple other devices. We don't really support automatic
* discovery on such setups, with the exception of dm-verity partitions. In this case there are
* two backing devices: the data partition and the hash partition. We are fine with such
* setups, however, only if both partitions are on the same physical device. Hence, let's
* verify this. */
u = strjoin(p, "/", de->d_name, "/../dev");
if (!u)
return -ENOMEM;
v = strjoin(p, "/", found->d_name, "/../dev");
if (!v)
return -ENOMEM;
r = read_one_line_file(u, &a);
if (r < 0)
return log_debug_errno(r, "Failed to read %s: %m", u);
r = read_one_line_file(v, &b);
if (r < 0)
return log_debug_errno(r, "Failed to read %s: %m", v);
/* Check if the parent device is the same. If not, then the two backing devices are on
* different physical devices, and we don't support that. */
if (!streq(a, b))
return -ENOTUNIQ;
}
found = de;
}
if (!found)
return -ENOENT;
q = strjoina(p, "/", found->d_name, "/dev");
r = read_one_line_file(q, &t);
if (r < 0)
return r;
if (sscanf(t, "%u:%u", &maj, &min) != 2)
return -EINVAL;
if (maj == 0)
return -ENOENT;
*ret = makedev(maj, min);
return 1;
}
int get_block_device_harder(const char *path, dev_t *ret) {
int r;
assert(path);
assert(ret);
/* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
* immediate parent, if there is one. */
r = get_block_device(path, ret);
if (r <= 0)
return r;
r = block_get_originating(*ret, ret);
if (r < 0)
log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
return 1;
}
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