diff options
author | Franck Bui <fbui@suse.com> | 2017-09-13 11:47:15 +0200 |
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committer | Franck Bui <fbui@suse.com> | 2017-09-13 11:49:43 +0200 |
commit | c43b2b9c71e6e5f9af90ca178674d248acb0b9fc (patch) | |
tree | a0e4227505723c25b291598692cce32399cfe98c /src/basic/util.c | |
parent | 3d4ec01269244c2d35a781abf748ea9ba57666e2 (diff) | |
download | systemd-c43b2b9c71e6e5f9af90ca178674d248acb0b9fc.tar.gz |
util: make get_block_device() available
Diffstat (limited to 'src/basic/util.c')
-rw-r--r-- | src/basic/util.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/src/basic/util.c b/src/basic/util.c index 2f45128ed4..daaee99284 100644 --- a/src/basic/util.c +++ b/src/basic/util.c @@ -34,6 +34,7 @@ #include <unistd.h> #include "alloc-util.h" +#include "btrfs-util.h" #include "build.h" #include "cgroup-util.h" #include "def.h" @@ -719,3 +720,133 @@ int version(void) { SYSTEMD_FEATURES); 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); + + return 0; +} + +int get_block_device_harder(const char *path, dev_t *dev) { + _cleanup_closedir_ DIR *d = NULL; + _cleanup_free_ char *p = NULL, *t = NULL; + struct dirent *de, *found = NULL; + const char *q; + unsigned maj, min; + dev_t dt; + int r; + + assert(path); + assert(dev); + + /* 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, &dt); + if (r <= 0) + return r; + + if (asprintf(&p, "/sys/dev/block/%u:%u/slaves", major(dt), minor(dt)) < 0) + return -ENOMEM; + + d = opendir(p); + if (!d) { + if (errno == ENOENT) + goto fallback; + + 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) { + log_debug_errno(r, "Failed to read %s: %m", u); + goto fallback; + } + + r = read_one_line_file(v, &b); + if (r < 0) { + log_debug_errno(r, "Failed to read %s: %m", v); + goto fallback; + } + + /* 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)) + goto fallback; + } + + found = de; + } + + if (!found) + goto fallback; + + q = strjoina(p, "/", found->d_name, "/dev"); + + r = read_one_line_file(q, &t); + if (r == -ENOENT) + goto fallback; + if (r < 0) + return r; + + if (sscanf(t, "%u:%u", &maj, &min) != 2) + return -EINVAL; + + if (maj == 0) + goto fallback; + + *dev = makedev(maj, min); + return 1; + +fallback: + *dev = dt; + return 1; +} |