2 * Copyright (C) 2018 Facebook
4 * This file is part of libbtrfsutil.
6 * libbtrfsutil is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * libbtrfsutil is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with libbtrfsutil. If not, see <http://www.gnu.org/licenses/>.
25 #include <sys/ioctl.h>
27 #include <sys/types.h>
29 #include <linux/magic.h>
31 #include "btrfsutil_internal.h"
34 * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening
35 * a file descriptor and calling it, because fstat() and fstatfs() don't accept
36 * file descriptors opened with O_PATH on old kernels (before v3.6 and before
37 * v3.12, respectively), but stat() and statfs() can be called on a path that
38 * the user doesn't have read or write permissions to.
40 PUBLIC enum btrfs_util_error btrfs_util_is_subvolume(const char *path)
46 ret = statfs(path, &sfs);
48 return BTRFS_UTIL_ERROR_STATFS_FAILED;
50 if (sfs.f_type != BTRFS_SUPER_MAGIC) {
52 return BTRFS_UTIL_ERROR_NOT_BTRFS;
55 ret = stat(path, &st);
57 return BTRFS_UTIL_ERROR_STAT_FAILED;
59 if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode)) {
61 return BTRFS_UTIL_ERROR_NOT_SUBVOLUME;
67 PUBLIC enum btrfs_util_error btrfs_util_is_subvolume_fd(int fd)
73 ret = fstatfs(fd, &sfs);
75 return BTRFS_UTIL_ERROR_STATFS_FAILED;
77 if (sfs.f_type != BTRFS_SUPER_MAGIC) {
79 return BTRFS_UTIL_ERROR_NOT_BTRFS;
84 return BTRFS_UTIL_ERROR_STAT_FAILED;
86 if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode)) {
88 return BTRFS_UTIL_ERROR_NOT_SUBVOLUME;
94 PUBLIC enum btrfs_util_error btrfs_util_subvolume_id(const char *path,
97 enum btrfs_util_error err;
100 fd = open(path, O_RDONLY);
102 return BTRFS_UTIL_ERROR_OPEN_FAILED;
104 err = btrfs_util_subvolume_id_fd(fd, id_ret);
105 SAVE_ERRNO_AND_CLOSE(fd);
109 PUBLIC enum btrfs_util_error btrfs_util_subvolume_id_fd(int fd,
112 struct btrfs_ioctl_ino_lookup_args args = {
114 .objectid = BTRFS_FIRST_FREE_OBJECTID,
118 ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
121 return BTRFS_UTIL_ERROR_INO_LOOKUP_FAILED;
124 *id_ret = args.treeid;
126 return BTRFS_UTIL_OK;
129 static enum btrfs_util_error openat_parent_and_name(int dirfd, const char *path,
130 char *name, size_t name_len,
133 char *tmp_path, *slash, *dirname, *basename;
136 /* Ignore trailing slashes. */
138 while (len > 1 && path[len - 1] == '/')
141 tmp_path = malloc(len + 1);
143 return BTRFS_UTIL_ERROR_NO_MEMORY;
144 memcpy(tmp_path, path, len);
145 tmp_path[len] = '\0';
147 slash = memrchr(tmp_path, '/', len);
148 if (slash == tmp_path) {
150 basename = tmp_path + 1;
154 basename = slash + 1;
160 len = strlen(basename);
161 if (len >= name_len) {
163 errno = ENAMETOOLONG;
164 return BTRFS_UTIL_ERROR_INVALID_ARGUMENT;
166 memcpy(name, basename, len);
169 *fd = openat(dirfd, dirname, O_RDONLY | O_DIRECTORY);
172 return BTRFS_UTIL_ERROR_OPEN_FAILED;
176 return BTRFS_UTIL_OK;
179 PUBLIC enum btrfs_util_error btrfs_util_create_subvolume(const char *path,
181 uint64_t *async_transid,
182 struct btrfs_util_qgroup_inherit *qgroup_inherit)
184 char name[BTRFS_SUBVOL_NAME_MAX + 1];
185 enum btrfs_util_error err;
188 err = openat_parent_and_name(AT_FDCWD, path, name, sizeof(name),
193 err = btrfs_util_create_subvolume_fd(parent_fd, name, flags,
194 async_transid, qgroup_inherit);
195 SAVE_ERRNO_AND_CLOSE(parent_fd);
199 PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_fd(int parent_fd,
202 uint64_t *async_transid,
203 struct btrfs_util_qgroup_inherit *qgroup_inherit)
205 struct btrfs_ioctl_vol_args_v2 args = {};
211 return BTRFS_UTIL_ERROR_INVALID_ARGUMENT;
215 args.flags |= BTRFS_SUBVOL_CREATE_ASYNC;
216 if (qgroup_inherit) {
217 args.flags |= BTRFS_SUBVOL_QGROUP_INHERIT;
218 args.qgroup_inherit = (struct btrfs_qgroup_inherit *)qgroup_inherit;
219 args.size = (sizeof(*args.qgroup_inherit) +
220 args.qgroup_inherit->num_qgroups *
221 sizeof(args.qgroup_inherit->qgroups[0]));
225 if (len >= sizeof(args.name)) {
226 errno = ENAMETOOLONG;
227 return BTRFS_UTIL_ERROR_INVALID_ARGUMENT;
229 memcpy(args.name, name, len);
230 args.name[len] = '\0';
232 ret = ioctl(parent_fd, BTRFS_IOC_SUBVOL_CREATE_V2, &args);
234 return BTRFS_UTIL_ERROR_SUBVOL_CREATE_FAILED;
237 *async_transid = args.transid;
239 return BTRFS_UTIL_OK;