// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package os
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import (
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"internal/syscall/windows"
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"sync"
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"syscall"
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"time"
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"unsafe"
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)
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// A fileStat is the implementation of FileInfo returned by Stat and Lstat.
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type fileStat struct {
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name string
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// from ByHandleFileInformation, Win32FileAttributeData and Win32finddata
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FileAttributes uint32
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CreationTime syscall.Filetime
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LastAccessTime syscall.Filetime
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LastWriteTime syscall.Filetime
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FileSizeHigh uint32
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FileSizeLow uint32
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// from Win32finddata
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Reserved0 uint32
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// what syscall.GetFileType returns
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filetype uint32
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// used to implement SameFile
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sync.Mutex
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path string
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vol uint32
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idxhi uint32
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idxlo uint32
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appendNameToPath bool
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}
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// newFileStatFromGetFileInformationByHandle calls GetFileInformationByHandle
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// to gather all required information about the file handle h.
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func newFileStatFromGetFileInformationByHandle(path string, h syscall.Handle) (fs *fileStat, err error) {
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var d syscall.ByHandleFileInformation
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err = syscall.GetFileInformationByHandle(h, &d)
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if err != nil {
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return nil, &PathError{"GetFileInformationByHandle", path, err}
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}
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var ti windows.FILE_ATTRIBUTE_TAG_INFO
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err = windows.GetFileInformationByHandleEx(h, windows.FileAttributeTagInfo, (*byte)(unsafe.Pointer(&ti)), uint32(unsafe.Sizeof(ti)))
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if err != nil {
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if errno, ok := err.(syscall.Errno); ok && errno == windows.ERROR_INVALID_PARAMETER {
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// It appears calling GetFileInformationByHandleEx with
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// FILE_ATTRIBUTE_TAG_INFO fails on FAT file system with
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// ERROR_INVALID_PARAMETER. Clear ti.ReparseTag in that
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// instance to indicate no symlinks are possible.
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ti.ReparseTag = 0
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} else {
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return nil, &PathError{"GetFileInformationByHandleEx", path, err}
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}
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}
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return &fileStat{
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name: basename(path),
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FileAttributes: d.FileAttributes,
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CreationTime: d.CreationTime,
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LastAccessTime: d.LastAccessTime,
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LastWriteTime: d.LastWriteTime,
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FileSizeHigh: d.FileSizeHigh,
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FileSizeLow: d.FileSizeLow,
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vol: d.VolumeSerialNumber,
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idxhi: d.FileIndexHigh,
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idxlo: d.FileIndexLow,
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Reserved0: ti.ReparseTag,
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// fileStat.path is used by os.SameFile to decide if it needs
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// to fetch vol, idxhi and idxlo. But these are already set,
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// so set fileStat.path to "" to prevent os.SameFile doing it again.
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}, nil
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}
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// newFileStatFromWin32finddata copies all required information
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// from syscall.Win32finddata d into the newly created fileStat.
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func newFileStatFromWin32finddata(d *syscall.Win32finddata) *fileStat {
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return &fileStat{
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FileAttributes: d.FileAttributes,
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CreationTime: d.CreationTime,
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LastAccessTime: d.LastAccessTime,
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LastWriteTime: d.LastWriteTime,
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FileSizeHigh: d.FileSizeHigh,
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FileSizeLow: d.FileSizeLow,
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Reserved0: d.Reserved0,
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}
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}
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func (fs *fileStat) isSymlink() bool {
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// Use instructions described at
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// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
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// to recognize whether it's a symlink.
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
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return false
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}
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return fs.Reserved0 == syscall.IO_REPARSE_TAG_SYMLINK ||
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fs.Reserved0 == windows.IO_REPARSE_TAG_MOUNT_POINT
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}
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func (fs *fileStat) Size() int64 {
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return int64(fs.FileSizeHigh)<<32 + int64(fs.FileSizeLow)
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}
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func (fs *fileStat) Mode() (m FileMode) {
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if fs == &devNullStat {
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return ModeDevice | ModeCharDevice | 0666
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}
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_READONLY != 0 {
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m |= 0444
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} else {
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m |= 0666
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}
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if fs.isSymlink() {
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return m | ModeSymlink
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}
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
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m |= ModeDir | 0111
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}
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switch fs.filetype {
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case syscall.FILE_TYPE_PIPE:
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m |= ModeNamedPipe
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case syscall.FILE_TYPE_CHAR:
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m |= ModeDevice | ModeCharDevice
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}
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return m
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}
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func (fs *fileStat) ModTime() time.Time {
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return time.Unix(0, fs.LastWriteTime.Nanoseconds())
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}
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// Sys returns syscall.Win32FileAttributeData for file fs.
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func (fs *fileStat) Sys() interface{} {
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return &syscall.Win32FileAttributeData{
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FileAttributes: fs.FileAttributes,
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CreationTime: fs.CreationTime,
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LastAccessTime: fs.LastAccessTime,
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LastWriteTime: fs.LastWriteTime,
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FileSizeHigh: fs.FileSizeHigh,
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FileSizeLow: fs.FileSizeLow,
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}
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}
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func (fs *fileStat) loadFileId() error {
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fs.Lock()
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defer fs.Unlock()
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if fs.path == "" {
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// already done
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return nil
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}
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var path string
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if fs.appendNameToPath {
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path = fs.path + `\` + fs.name
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} else {
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path = fs.path
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}
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pathp, err := syscall.UTF16PtrFromString(path)
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if err != nil {
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return err
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}
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attrs := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
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if fs.isSymlink() {
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// Use FILE_FLAG_OPEN_REPARSE_POINT, otherwise CreateFile will follow symlink.
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// See https://docs.microsoft.com/en-us/windows/desktop/FileIO/symbolic-link-effects-on-file-systems-functions#createfile-and-createfiletransacted
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attrs |= syscall.FILE_FLAG_OPEN_REPARSE_POINT
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}
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h, err := syscall.CreateFile(pathp, 0, 0, nil, syscall.OPEN_EXISTING, attrs, 0)
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if err != nil {
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return err
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}
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defer syscall.CloseHandle(h)
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var i syscall.ByHandleFileInformation
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err = syscall.GetFileInformationByHandle(h, &i)
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if err != nil {
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return err
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}
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fs.path = ""
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fs.vol = i.VolumeSerialNumber
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fs.idxhi = i.FileIndexHigh
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fs.idxlo = i.FileIndexLow
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return nil
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}
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// devNullStat is fileStat structure describing DevNull file ("NUL").
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var devNullStat = fileStat{
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name: DevNull,
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// hopefully this will work for SameFile
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vol: 0,
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idxhi: 0,
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idxlo: 0,
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}
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func sameFile(fs1, fs2 *fileStat) bool {
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e := fs1.loadFileId()
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if e != nil {
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return false
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}
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e = fs2.loadFileId()
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if e != nil {
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return false
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}
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return fs1.vol == fs2.vol && fs1.idxhi == fs2.idxhi && fs1.idxlo == fs2.idxlo
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}
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// For testing.
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func atime(fi FileInfo) time.Time {
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return time.Unix(0, fi.Sys().(*syscall.Win32FileAttributeData).LastAccessTime.Nanoseconds())
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}
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