/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <linux/btrfs.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include "alloc-util.h"

#include "btrfs.h"

#include "errno-util.h"

#include "fd-util.h"

#include "path-util.h"

#include "string-util.h"

int btrfs_validate_subvolume_name(const char *name) {

        if (!filename_is_valid(name))

                return -EINVAL;

        if (strlen(name) > BTRFS_SUBVOL_NAME_MAX)

                return -E2BIG;

        return 0;

}

static int extract_subvolume_name(const char *path, char **ret) {

        _cleanup_free_ char *fn = NULL;

        int r;

        assert(path);

        assert(ret);

        r = path_extract_filename(path, &fn);

        if (r < 0)

                return r;

        r = btrfs_validate_subvolume_name(fn);

        if (r < 0)

                return r;

        *ret = TAKE_PTR(fn);

        return 0;

}

int btrfs_subvol_make(int dir_fd, const char *path) {

        struct btrfs_ioctl_vol_args args = {};

        _cleanup_free_ char *subvolume = NULL, *parent = NULL;

        _cleanup_close_ int fd = -EBADF;

        int r;

        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);

        assert(!isempty(path));

        r = extract_subvolume_name(path, &subvolume);

        if (r < 0)

                return r;

        r = path_extract_directory(path, &parent);

        if (r < 0) {

                if (r != -EDESTADDRREQ) /* Propagate error, unless only a filename was specified, which is OK */

                        return r;

                dir_fd = fd_reopen_condition(dir_fd, O_CLOEXEC, O_PATH, &fd); /* drop O_PATH if it is set */

                if (dir_fd < 0)

                        return dir_fd;

        } else {

                fd = openat(dir_fd, parent, O_DIRECTORY|O_RDONLY|O_CLOEXEC, 0);

                if (fd < 0)

                        return -errno;

                dir_fd = fd;

        }

        strncpy(args.name, subvolume, sizeof(args.name)-1);

        return RET_NERRNO(ioctl(dir_fd, BTRFS_IOC_SUBVOL_CREATE, &args));

}

int btrfs_subvol_make_fallback(int dir_fd, const char *path, mode_t mode) {

        mode_t old, combined;

        int r;

        assert(path);

        /* Let's work like mkdir(), i.e. take the specified mode, and mask it with the current umask. */

        old = umask(~mode);

        combined = old | ~mode;

        if (combined != ~mode)

                umask(combined);

        r = btrfs_subvol_make(dir_fd, path);

        umask(old);

        if (r >= 0)

                return 1; /* subvol worked */

        if (!ERRNO_IS_NOT_SUPPORTED(r))

                return r;

        if (mkdirat(dir_fd, path, mode) < 0)

                return -errno;

        return 0; /* plain directory */

}