diff options
Diffstat (limited to 'libbtrfsutil/subvolume.c')
-rw-r--r-- | libbtrfsutil/subvolume.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/libbtrfsutil/subvolume.c b/libbtrfsutil/subvolume.c new file mode 100644 index 00000000..7ae8142c --- /dev/null +++ b/libbtrfsutil/subvolume.c @@ -0,0 +1,125 @@ +/* + * Copyright (C) 2018 Facebook + * + * This file is part of libbtrfsutil. + * + * libbtrfsutil is free software: you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * libbtrfsutil is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with libbtrfsutil. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/vfs.h> +#include <linux/magic.h> + +#include "btrfsutil_internal.h" + +/* + * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening + * a file descriptor and calling it, because fstat() and fstatfs() don't accept + * file descriptors opened with O_PATH on old kernels (before v3.6 and before + * v3.12, respectively), but stat() and statfs() can be called on a path that + * the user doesn't have read or write permissions to. + */ +PUBLIC enum btrfs_util_error btrfs_util_is_subvolume(const char *path) +{ + struct statfs sfs; + struct stat st; + int ret; + + ret = statfs(path, &sfs); + if (ret == -1) + return BTRFS_UTIL_ERROR_STATFS_FAILED; + + if (sfs.f_type != BTRFS_SUPER_MAGIC) { + errno = EINVAL; + return BTRFS_UTIL_ERROR_NOT_BTRFS; + } + + ret = stat(path, &st); + if (ret == -1) + return BTRFS_UTIL_ERROR_STAT_FAILED; + + if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode)) { + errno = EINVAL; + return BTRFS_UTIL_ERROR_NOT_SUBVOLUME; + } + + return BTRFS_UTIL_OK; +} + +PUBLIC enum btrfs_util_error btrfs_util_is_subvolume_fd(int fd) +{ + struct statfs sfs; + struct stat st; + int ret; + + ret = fstatfs(fd, &sfs); + if (ret == -1) + return BTRFS_UTIL_ERROR_STATFS_FAILED; + + if (sfs.f_type != BTRFS_SUPER_MAGIC) { + errno = EINVAL; + return BTRFS_UTIL_ERROR_NOT_BTRFS; + } + + ret = fstat(fd, &st); + if (ret == -1) + return BTRFS_UTIL_ERROR_STAT_FAILED; + + if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode)) { + errno = EINVAL; + return BTRFS_UTIL_ERROR_NOT_SUBVOLUME; + } + + return BTRFS_UTIL_OK; +} + +PUBLIC enum btrfs_util_error btrfs_util_subvolume_id(const char *path, + uint64_t *id_ret) +{ + enum btrfs_util_error err; + int fd; + + fd = open(path, O_RDONLY); + if (fd == -1) + return BTRFS_UTIL_ERROR_OPEN_FAILED; + + err = btrfs_util_subvolume_id_fd(fd, id_ret); + SAVE_ERRNO_AND_CLOSE(fd); + return err; +} + +PUBLIC enum btrfs_util_error btrfs_util_subvolume_id_fd(int fd, + uint64_t *id_ret) +{ + struct btrfs_ioctl_ino_lookup_args args = { + .treeid = 0, + .objectid = BTRFS_FIRST_FREE_OBJECTID, + }; + int ret; + + ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args); + if (ret == -1) { + close(fd); + return BTRFS_UTIL_ERROR_INO_LOOKUP_FAILED; + } + + *id_ret = args.treeid; + + return BTRFS_UTIL_OK; +} |