boff := 0 // starting read position in buf
	nbuf := 0 // end valid data in buf

	for {
		if boff >= nbuf {
			boff = 0
			stop := globalOSMetrics.time(osMetricReadDirent)
			nbuf, err = syscall.ReadDirent(fd, buf)
			stop()
			if err != nil {
				if isSysErrNotDir(err) {
					return nil
				}
				err = osErrToFileErr(err)
				if err == errFileNotFound {
					return nil
				}
				return err

pkg syscall (freebsd-arm64), func RawSyscall6(uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr) (uintptr, uintptr, Errno)
pkg syscall (freebsd-arm64), func Read(int, []uint8) (int, error)
pkg syscall (freebsd-arm64), func ReadDirent(int, []uint8) (int, error)
pkg syscall (freebsd-arm64), func Recvfrom(int, []uint8, int) (int, Sockaddr, error)
pkg syscall (freebsd-arm64), func Recvmsg(int, []uint8, []uint8, int) (int, int, int, Sockaddr, error)

pkg syscall (darwin-arm64), func RawSyscall6(uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr) (uintptr, uintptr, Errno)
pkg syscall (darwin-arm64), func Read(int, []uint8) (int, error)
pkg syscall (darwin-arm64), func ReadDirent(int, []uint8) (int, error)
pkg syscall (darwin-arm64), func Recvfrom(int, []uint8, int) (int, Sockaddr, error)
pkg syscall (darwin-arm64), func Recvmsg(int, []uint8, []uint8, int) (int, int, int, Sockaddr, error)

pkg syscall (freebsd-riscv64), func Read(int, []uint8) (int, error) #53466
pkg syscall (freebsd-riscv64), func ReadDirent(int, []uint8) (int, error) #53466
pkg syscall (freebsd-riscv64), func Recvfrom(int, []uint8, int) (int, Sockaddr, error) #53466