diff options
Diffstat (limited to 'utils.c')
| -rw-r--r-- | utils.c | 31 |
1 files changed, 30 insertions, 1 deletions
@@ -1172,6 +1172,28 @@ static int is_loop_device (const char* device) { MAJOR(statbuf.st_rdev) == LOOP_MAJOR); } +/* + * Takes a loop device path (e.g. /dev/loop0) and returns + * the associated file (e.g. /images/my_btrfs.img) using + * loopdev API + */ +static int resolve_loop_device_with_loopdev(const char* loop_dev, char* loop_file) +{ + int fd; + struct loop_info64 lo64; + + fd = open(loop_dev, O_RDONLY | O_NONBLOCK); + if (fd < 0) + return -errno; + if (ioctl(fd, LOOP_GET_STATUS64, &lo64) < 0) + return -errno; + + memcpy(loop_file, lo64.lo_file_name, strlen(lo64.lo_file_name) + 1); + if (close(fd) < 0) + return -errno; + + return 0; +} /* Takes a loop device path (e.g. /dev/loop0) and returns * the associated file (e.g. /images/my_btrfs.img) */ @@ -1187,8 +1209,15 @@ static int resolve_loop_device(const char* loop_dev, char* loop_file, if (!realpath(loop_dev, real_loop_dev)) return -errno; snprintf(p, PATH_MAX, "/sys/block/%s/loop/backing_file", strrchr(real_loop_dev, '/')); - if (!(f = fopen(p, "r"))) + if (!(f = fopen(p, "r"))) { + if (errno == ENOENT) + /* + * It's possibly a partitioned loop device, which is + * resolvable with loopdev API. + */ + return resolve_loop_device_with_loopdev(loop_dev, loop_file); return -errno; + } snprintf(fmt, 20, "%%%i[^\n]", max_len-1); ret = fscanf(f, fmt, loop_file); |