return ignoringEINTR(func() error {
		return syscall.Fchown(fd.Sysfd, uid, gid)
	})
}

// Ftruncate wraps syscall.Ftruncate.
func (fd *FD) Ftruncate(size int64) error {
	if err := fd.incref(); err != nil {
		return err
	}
	defer fd.decref()
	return ignoringEINTR(func() error {
		return syscall.Ftruncate(fd.Sysfd, size)
	})
}

// RawControl invokes the user-defined function f for a non-IO
// operation.

//go:cgo_import_dynamic execve execve ""
//go:cgo_import_dynamic exit exit ""
//go:cgo_import_dynamic fstat$INODE64 fstat$INODE64 ""
//go:cgo_import_dynamic ftruncate ftruncate ""
//go:cgo_import_dynamic getpid getpid ""
//go:cgo_import_dynamic getrlimit getrlimit ""
//go:cgo_import_dynamic gettimeofday gettimeofday ""
//go:cgo_import_dynamic getuid getuid ""

//go:cgo_import_dynamic dyld_shared_cache_iterate_text dyld_shared_cache_iterate_text ""
//go:cgo_import_dynamic execve execve ""
//go:cgo_import_dynamic exit exit ""
//go:cgo_import_dynamic fstat fstat ""
//go:cgo_import_dynamic ftruncate ftruncate ""
//go:cgo_import_dynamic getpid getpid ""
//go:cgo_import_dynamic getrlimit getrlimit ""
//go:cgo_import_dynamic gettimeofday gettimeofday ""
//go:cgo_import_dynamic getuid getuid ""

// do not require flushing because they are not necessary for a subsequent data
// read to be handled correctly. On the other hand, a change to the file size
// (st_size, as made by say ftruncate(2)), would require a metadata flush.
//
// The aim of fdatasync() is to reduce disk activity for applications that
// do not require all metadata to be synchronized with the disk.
func Fdatasync(f *os.File) error {

		// while we use its fd, preventing its finalizer from
		// executing.
		f := os.NewFile(uintptr(fd), name)
		defer f.Close()

		if err := syscall.Ftruncate(int(f.Fd()), 1<<20); err != nil {
			t.Fatalf("Ftruncate(1<<20) failed: %v", err)
		}
		if err := syscall.FcntlFlock(f.Fd(), syscall.F_SETLK, &flock); err != nil {
			t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
		}

//sys	Fstat(fd int, stat *Stat_t) (err error)
//sys	Fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_NEWFSTATAT
//sys	Fstatfs(fd int, buf *Statfs_t) (err error)
//sys	Ftruncate(fd int, length int64) (err error)
//sysnb	Getegid() (egid int)
//sysnb	Geteuid() (euid int)
//sysnb	Getgid() (gid int)
//sysnb	Getrlimit(resource int, rlim *Rlimit) (err error) = SYS_UGETRLIMIT
//sysnb	Getuid() (uid int)

//sys	Fstat(fd int, stat *Stat_t) (err error)
//sys	Fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_FSTATAT64
//sys	Fstatfs(fd int, buf *Statfs_t) (err error)
//sys	Ftruncate(fd int, length int64) (err error)
//sysnb	Getegid() (egid int)
//sysnb	Geteuid() (euid int)
//sysnb	Getgid() (gid int)
//sysnb	Getrlimit(resource int, rlim *Rlimit) (err error)
//sysnb	Getuid() (uid int)

//sys	Fstat(fd int, stat *Stat_t) (err error)
//sys	fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_NEWFSTATAT
//sys	Fstatfs(fd int, buf *Statfs_t) (err error)
//sys	Ftruncate(fd int, length int64) (err error)
//sysnb	Getegid() (egid int)
//sysnb	Geteuid() (euid int)
//sysnb	Getgid() (gid int)
//sysnb	Getrlimit(resource int, rlim *Rlimit) (err error) = SYS_UGETRLIMIT
//sysnb	Getuid() (uid int)

		return err
	}
	_, err := fsCall("rename", from, to)
	return err
}

func Truncate(path string, length int64) error {
	if err := checkPath(path); err != nil {
		return err
	}
	_, err := fsCall("truncate", path, length)
	return err
}

func Ftruncate(fd int, length int64) error {
	_, err := fsCall("ftruncate", fd, length)
	return err
}

func Getcwd(buf []byte) (n int, err error) {

//sys	Fstat(fd int, stat *Stat_t) (err error)
//sys	Fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_NEWFSTATAT
//sys	Fstatfs(fd int, buf *Statfs_t) (err error)
//sys	Ftruncate(fd int, length int64) (err error)
//sysnb	Getegid() (egid int)
//sysnb	Geteuid() (euid int)
//sysnb	Getgid() (gid int)
//sysnb	Getrlimit(resource int, rlim *Rlimit) (err error)
//sysnb	Getuid() (uid int)