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/*
* 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;
}
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