mirror of
https://github.com/morgan9e/systemd
synced 2026-04-14 16:37:19 +09:00
7176f06c9e
No actual code changes, just splitting out of some dev_t handling related calls from stat-util.[ch], they are quite a number already, and deserve their own module now I think. Also, try to settle on the name "devnum" as the name for the concept, instead of "devno" or "dev" or "devid". "devnum" is the name exported in udev APIs, hence probably best to stick to that. (this just renames a few symbols to "devum", local variables are left untouched, to make the patch not too invasive) No actual code changes.
380 lines
11 KiB
C
380 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <sys/file.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "blockdev-util.h"
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#include "btrfs-util.h"
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#include "devnum-util.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "missing_magic.h"
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#include "parse-util.h"
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int block_get_whole_disk(dev_t d, dev_t *ret) {
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char p[SYS_BLOCK_PATH_MAX("/partition")];
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_cleanup_free_ char *s = NULL;
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dev_t devt;
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int r;
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assert(ret);
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if (major(d) == 0)
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return -ENODEV;
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/* If it has a queue this is good enough for us */
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xsprintf_sys_block_path(p, "/queue", d);
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if (access(p, F_OK) >= 0) {
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*ret = d;
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return 0;
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}
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if (errno != ENOENT)
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return -errno;
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/* If it is a partition find the originating device */
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xsprintf_sys_block_path(p, "/partition", d);
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if (access(p, F_OK) < 0)
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return -errno;
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/* Get parent dev_t */
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xsprintf_sys_block_path(p, "/../dev", d);
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r = read_one_line_file(p, &s);
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if (r < 0)
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return r;
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r = parse_devnum(s, &devt);
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if (r < 0)
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return r;
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/* Only return this if it is really good enough for us. */
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xsprintf_sys_block_path(p, "/queue", devt);
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if (access(p, F_OK) < 0)
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return -errno;
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*ret = devt;
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return 1;
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}
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int get_block_device_fd(int fd, dev_t *ret) {
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struct stat st;
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int r;
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assert(fd >= 0);
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assert(ret);
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/* Gets the block device directly backing a file system. If the block device is encrypted, returns
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* the device mapper block device. */
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if (fstat(fd, &st))
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return -errno;
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if (major(st.st_dev) != 0) {
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*ret = st.st_dev;
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return 1;
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}
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r = btrfs_get_block_device_fd(fd, ret);
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if (r > 0)
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return 1;
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if (r != -ENOTTY) /* not btrfs */
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return r;
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*ret = 0;
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return 0;
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}
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int get_block_device(const char *path, dev_t *ret) {
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_cleanup_close_ int fd = -1;
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assert(path);
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assert(ret);
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fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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return get_block_device_fd(fd, ret);
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}
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int block_get_originating(dev_t dt, dev_t *ret) {
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_cleanup_closedir_ DIR *d = NULL;
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_cleanup_free_ char *t = NULL;
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char p[SYS_BLOCK_PATH_MAX("/slaves")];
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_cleanup_free_ char *first_found = NULL;
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const char *q;
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dev_t devt;
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int r;
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/* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
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* trying to find the next underlying layer. */
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xsprintf_sys_block_path(p, "/slaves", dt);
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d = opendir(p);
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if (!d)
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return -errno;
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FOREACH_DIRENT_ALL(de, d, return -errno) {
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if (dot_or_dot_dot(de->d_name))
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continue;
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if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
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continue;
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if (first_found) {
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_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
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/* We found a device backed by multiple other devices. We don't really support
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* automatic discovery on such setups, with the exception of dm-verity partitions. In
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* this case there are two backing devices: the data partition and the hash
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* partition. We are fine with such setups, however, only if both partitions are on
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* the same physical device. Hence, let's verify this by iterating over every node
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* in the 'slaves/' directory and comparing them with the first that gets returned by
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* readdir(), to ensure they all point to the same device. */
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u = path_join(p, de->d_name, "../dev");
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if (!u)
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return -ENOMEM;
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v = path_join(p, first_found, "../dev");
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if (!v)
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return -ENOMEM;
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r = read_one_line_file(u, &a);
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if (r < 0)
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return log_debug_errno(r, "Failed to read %s: %m", u);
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r = read_one_line_file(v, &b);
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if (r < 0)
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return log_debug_errno(r, "Failed to read %s: %m", v);
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/* Check if the parent device is the same. If not, then the two backing devices are on
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* different physical devices, and we don't support that. */
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if (!streq(a, b))
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return -ENOTUNIQ;
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} else {
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first_found = strdup(de->d_name);
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if (!first_found)
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return -ENOMEM;
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}
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}
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if (!first_found)
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return -ENOENT;
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q = strjoina(p, "/", first_found, "/dev");
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r = read_one_line_file(q, &t);
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if (r < 0)
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return r;
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r = parse_devnum(t, &devt);
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if (r < 0)
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return -EINVAL;
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if (major(devt) == 0)
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return -ENOENT;
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*ret = devt;
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return 1;
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}
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int get_block_device_harder_fd(int fd, dev_t *ret) {
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int r;
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assert(fd >= 0);
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assert(ret);
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/* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
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* immediate parent, if there is one. */
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r = get_block_device_fd(fd, ret);
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if (r <= 0)
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return r;
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r = block_get_originating(*ret, ret);
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if (r < 0)
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log_debug_errno(r, "Failed to chase block device, ignoring: %m");
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return 1;
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}
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int get_block_device_harder(const char *path, dev_t *ret) {
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_cleanup_close_ int fd = -1;
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assert(path);
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assert(ret);
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fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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return get_block_device_harder_fd(fd, ret);
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}
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int lock_whole_block_device(dev_t devt, int operation) {
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_cleanup_free_ char *whole_node = NULL;
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_cleanup_close_ int lock_fd = -1;
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dev_t whole_devt;
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int r;
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/* Let's get a BSD file lock on the whole block device, as per: https://systemd.io/BLOCK_DEVICE_LOCKING */
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r = block_get_whole_disk(devt, &whole_devt);
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if (r < 0)
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return r;
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r = device_path_make_major_minor(S_IFBLK, whole_devt, &whole_node);
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if (r < 0)
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return r;
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lock_fd = open(whole_node, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
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if (lock_fd < 0)
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return -errno;
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if (flock(lock_fd, operation) < 0)
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return -errno;
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return TAKE_FD(lock_fd);
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}
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int blockdev_partscan_enabled(int fd) {
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_cleanup_free_ char *p = NULL, *buf = NULL;
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unsigned long long ull;
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struct stat st;
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int r;
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/* Checks if partition scanning is correctly enabled on the block device */
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if (fstat(fd, &st) < 0)
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return -errno;
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if (!S_ISBLK(st.st_mode))
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return -ENOTBLK;
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if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
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return -ENOMEM;
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r = read_one_line_file(p, &buf);
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if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
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* partition block device, not the whole block device. And that means we have no
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* partition scanning on for it (we do for its parent, but not for the partition
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* itself). */
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return false;
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if (r < 0)
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return r;
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r = safe_atollu_full(buf, 16, &ull);
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if (r < 0)
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return r;
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#ifndef GENHD_FL_NO_PART_SCAN
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#define GENHD_FL_NO_PART_SCAN (0x0200)
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#endif
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return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
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}
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static int blockdev_is_encrypted(const char *sysfs_path, unsigned depth_left) {
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_cleanup_free_ char *p = NULL, *uuids = NULL;
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_cleanup_closedir_ DIR *d = NULL;
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int r, found_encrypted = false;
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assert(sysfs_path);
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if (depth_left == 0)
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return -EINVAL;
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p = path_join(sysfs_path, "dm/uuid");
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if (!p)
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return -ENOMEM;
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r = read_one_line_file(p, &uuids);
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if (r != -ENOENT) {
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if (r < 0)
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return r;
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/* The DM device's uuid attribute is prefixed with "CRYPT-" if this is a dm-crypt device. */
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if (startswith(uuids, "CRYPT-"))
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return true;
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}
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/* Not a dm-crypt device itself. But maybe it is on top of one? Follow the links in the "slaves/"
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* subdir. */
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p = mfree(p);
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p = path_join(sysfs_path, "slaves");
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if (!p)
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return -ENOMEM;
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d = opendir(p);
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if (!d) {
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if (errno == ENOENT) /* Doesn't have underlying devices */
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return false;
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return -errno;
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}
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for (;;) {
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_cleanup_free_ char *q = NULL;
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struct dirent *de;
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errno = 0;
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de = readdir_no_dot(d);
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if (!de) {
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if (errno != 0)
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return -errno;
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break; /* No more underlying devices */
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}
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q = path_join(p, de->d_name);
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if (!q)
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return -ENOMEM;
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r = blockdev_is_encrypted(q, depth_left - 1);
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if (r < 0)
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return r;
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if (r == 0) /* we found one that is not encrypted? then propagate that immediately */
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return false;
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found_encrypted = true;
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}
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return found_encrypted;
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}
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int fd_is_encrypted(int fd) {
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char p[SYS_BLOCK_PATH_MAX(NULL)];
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dev_t devt;
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int r;
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r = get_block_device_fd(fd, &devt);
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if (r < 0)
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return r;
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if (r == 0) /* doesn't have a block device */
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return false;
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xsprintf_sys_block_path(p, NULL, devt);
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return blockdev_is_encrypted(p, 10 /* safety net: maximum recursion depth */);
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}
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int path_is_encrypted(const char *path) {
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char p[SYS_BLOCK_PATH_MAX(NULL)];
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dev_t devt;
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int r;
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r = get_block_device(path, &devt);
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if (r < 0)
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return r;
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if (r == 0) /* doesn't have a block device */
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return false;
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xsprintf_sys_block_path(p, NULL, devt);
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return blockdev_is_encrypted(p, 10 /* safety net: maximum recursion depth */);
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}
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