package cmd

import (
	"bytes"
	"fmt"
	"syscall"
	"unsafe"
)

func direntNamlen(dirent *syscall.Dirent) (uint64, error) {
	const fixedHdr = uint16(unsafe.Offsetof(syscall.Dirent{}.Name))
	nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))
	const nameBufLen = uint16(len(nameBuf))
	limit := dirent.Reclen - fixedHdr
	if limit > nameBufLen {
		limit = nameBufLen
	}
	// Avoid bugs in long file names

func parseDirEnt(buf []byte) (consumed int, name []byte, typ os.FileMode, err error) {
	// golang.org/issue/15653
	dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[0]))
	if v := unsafe.Offsetof(dirent.Reclen) + unsafe.Sizeof(dirent.Reclen); uintptr(len(buf)) < v {
		return consumed, nil, typ, fmt.Errorf("buf size of %d smaller than dirent header size %d", len(buf), v)
	}
	if len(buf) < int(dirent.Reclen) {