summaryrefslogtreecommitdiffstats
path: root/src/basic/blockdev-util.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--src/basic/blockdev-util.c181
1 files changed, 181 insertions, 0 deletions
diff --git a/src/basic/blockdev-util.c b/src/basic/blockdev-util.c
new file mode 100644
index 0000000..3017ecd
--- /dev/null
+++ b/src/basic/blockdev-util.c
@@ -0,0 +1,181 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#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 "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 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 = 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 -ENOENT;
+
+ *ret = devt;
+ 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;
+ 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 = 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;
+
+ 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;
+}