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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/file.h>
#include <unistd.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_magic.h"
#include "parse-util.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;
dev_t devt;
int r;
assert(ret);
if (major(d) == 0)
return -ENODEV;
/* 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 (errno != ENOENT)
return -errno;
/* If it is a partition find the originating device */
xsprintf_sys_block_path(p, "/partition", d);
if (access(p, F_OK) < 0)
return -errno;
/* Get parent dev_t */
xsprintf_sys_block_path(p, "/../dev", d);
r = read_one_line_file(p, &s);
if (r < 0)
return r;
r = parse_dev(s, &devt);
if (r < 0)
return r;
/* Only return this if it is really good enough for us. */
xsprintf_sys_block_path(p, "/queue", devt);
if (access(p, F_OK) < 0)
return -errno;
*ret = devt;
return 1;
}
int get_block_device(const char *path, dev_t *ret) {
_cleanup_close_ int fd = -1;
struct stat st;
int r;
assert(path);
assert(ret);
/* Gets the block device directly backing a file system. If the block device is encrypted, returns
* the device mapper block device. */
fd = open(path, O_NOFOLLOW|O_CLOEXEC);
if (fd < 0)
return -errno;
if (fstat(fd, &st))
return -errno;
if (major(st.st_dev) != 0) {
*ret = st.st_dev;
return 1;
}
r = btrfs_get_block_device_fd(fd, ret);
if (r > 0)
return 1;
if (r != -ENOTTY) /* not btrfs */
return r;
*ret = 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;
const char *q;
dev_t devt;
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 = path_join(p, de->d_name, "../dev");
if (!u)
return -ENOMEM;
v = path_join(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;
r = parse_dev(t, &devt);
if (r < 0)
return -EINVAL;
if (major(devt) == 0)
return -ENOENT;
*ret = devt;
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;
}
int lock_whole_block_device(dev_t devt, int operation) {
_cleanup_free_ char *whole_node = NULL;
_cleanup_close_ int lock_fd = -1;
dev_t whole_devt;
int r;
/* Let's get a BSD file lock on the whole block device, as per: https://systemd.io/BLOCK_DEVICE_LOCKING */
r = block_get_whole_disk(devt, &whole_devt);
if (r < 0)
return r;
r = device_path_make_major_minor(S_IFBLK, whole_devt, &whole_node);
if (r < 0)
return r;
lock_fd = open(whole_node, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
if (lock_fd < 0)
return -errno;
if (flock(lock_fd, operation) < 0)
return -errno;
return TAKE_FD(lock_fd);
}
int blockdev_partscan_enabled(int fd) {
_cleanup_free_ char *p = NULL, *buf = NULL;
unsigned long long ull;
struct stat st;
int r;
/* Checks if partition scanning is correctly enabled on the block device */
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
return -ENOMEM;
r = read_one_line_file(p, &buf);
if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
* partition block device, not the whole block device. And that means we have no
* partition scanning on for it (we do for its parent, but not for the partition
* itself). */
return false;
if (r < 0)
return r;
r = safe_atollu_full(buf, 16, &ull);
if (r < 0)
return r;
#ifndef GENHD_FL_NO_PART_SCAN
#define GENHD_FL_NO_PART_SCAN (0x0200)
#endif
return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
}
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