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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package os
import (
"internal/syscall/windows"
"io"
"io/fs"
"runtime"
"sync"
"syscall"
"unsafe"
)
// Auxiliary information if the File describes a directory
type dirInfo struct {
// buf is a slice pointer so the slice header
// does not escape to the heap when returning
// buf to dirBufPool.
buf *[]byte // buffer for directory I/O
bufp int // location of next record in buf
vol uint32
}
const (
// dirBufSize is the size of the dirInfo buffer.
// The buffer must be big enough to hold at least a single entry.
// The filename alone can be 512 bytes (MAX_PATH*2), and the fixed part of
// the FILE_ID_BOTH_DIR_INFO structure is 105 bytes, so dirBufSize
// should not be set below 1024 bytes (512+105+safety buffer).
// Windows 8.1 and earlier only works with buffer sizes up to 64 kB.
dirBufSize = 64 * 1024 // 64kB
)
var dirBufPool = sync.Pool{
New: func() any {
// The buffer must be at least a block long.
buf := make([]byte, dirBufSize)
return &buf
},
}
func (d *dirInfo) close() {
if d.buf != nil {
dirBufPool.Put(d.buf)
d.buf = nil
}
}
func (file *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
// If this file has no dirinfo, create one.
var infoClass uint32 = windows.FileIdBothDirectoryInfo
if file.dirinfo == nil {
// vol is used by os.SameFile.
// It is safe to query it once and reuse the value.
// Hard links are not allowed to reference files in other volumes.
// Junctions and symbolic links can reference files and directories in other volumes,
// but the reparse point should still live in the parent volume.
var vol uint32
err = windows.GetVolumeInformationByHandle(file.pfd.Sysfd, nil, 0, &vol, nil, nil, nil, 0)
runtime.KeepAlive(file)
if err != nil {
err = &PathError{Op: "readdir", Path: file.name, Err: err}
return
}
infoClass = windows.FileIdBothDirectoryRestartInfo
file.dirinfo = new(dirInfo)
file.dirinfo.buf = dirBufPool.Get().(*[]byte)
file.dirinfo.vol = vol
}
d := file.dirinfo
wantAll := n <= 0
if wantAll {
n = -1
}
for n != 0 {
// Refill the buffer if necessary
if d.bufp == 0 {
err = windows.GetFileInformationByHandleEx(file.pfd.Sysfd, infoClass, (*byte)(unsafe.Pointer(&(*d.buf)[0])), uint32(len(*d.buf)))
runtime.KeepAlive(file)
if err != nil {
if err == syscall.ERROR_NO_MORE_FILES {
break
}
if s, _ := file.Stat(); s != nil && !s.IsDir() {
err = &PathError{Op: "readdir", Path: file.name, Err: syscall.ENOTDIR}
} else {
err = &PathError{Op: "GetFileInformationByHandleEx", Path: file.name, Err: err}
}
return
}
infoClass = windows.FileIdBothDirectoryInfo
}
// Drain the buffer
var islast bool
for n != 0 && !islast {
info := (*windows.FILE_ID_BOTH_DIR_INFO)(unsafe.Pointer(&(*d.buf)[d.bufp]))
d.bufp += int(info.NextEntryOffset)
islast = info.NextEntryOffset == 0
if islast {
d.bufp = 0
}
nameslice := unsafe.Slice(&info.FileName[0], info.FileNameLength/2)
name := syscall.UTF16ToString(nameslice)
if name == "." || name == ".." { // Useless names
continue
}
if mode == readdirName {
names = append(names, name)
} else {
f := newFileStatFromFileIDBothDirInfo(info)
f.name = name
f.vol = d.vol
// f.path is used by os.SameFile to decide if it needs
// to fetch vol, idxhi and idxlo. But these are already set,
// so set f.path to "" to prevent os.SameFile doing it again.
f.path = ""
if mode == readdirDirEntry {
dirents = append(dirents, dirEntry{f})
} else {
infos = append(infos, f)
}
}
n--
}
}
if !wantAll && len(names)+len(dirents)+len(infos) == 0 {
return nil, nil, nil, io.EOF
}
return names, dirents, infos, nil
}
type dirEntry struct {
fs *fileStat
}
func (de dirEntry) Name() string { return de.fs.Name() }
func (de dirEntry) IsDir() bool { return de.fs.IsDir() }
func (de dirEntry) Type() FileMode { return de.fs.Mode().Type() }
func (de dirEntry) Info() (FileInfo, error) { return de.fs, nil }
func (de dirEntry) String() string {
return fs.FormatDirEntry(de)
}
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