// 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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"syscall"
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"unsafe"
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)
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// isNulName reports whether name is NUL file name.
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// For example, it returns true for both "NUL" and "nul".
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func isNulName(name string) bool {
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if len(name) != 3 {
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return false
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}
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if name[0] != 'n' && name[0] != 'N' {
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return false
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}
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if name[1] != 'u' && name[1] != 'U' {
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return false
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}
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if name[2] != 'l' && name[2] != 'L' {
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return false
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}
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return true
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}
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// Stat returns the FileInfo structure describing file.
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// If there is an error, it will be of type *PathError.
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func (file *File) Stat() (FileInfo, error) {
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if file == nil {
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return nil, ErrInvalid
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}
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if file.isdir() {
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// I don't know any better way to do that for directory
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return Stat(file.dirinfo.path)
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}
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if isNulName(file.name) {
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return &devNullStat, nil
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}
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ft, err := file.pfd.GetFileType()
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if err != nil {
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return nil, &PathError{"GetFileType", file.name, err}
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}
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switch ft {
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case syscall.FILE_TYPE_PIPE, syscall.FILE_TYPE_CHAR:
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return &fileStat{name: basename(file.name), filetype: ft}, nil
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}
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fs, err := newFileStatFromGetFileInformationByHandle(file.name, file.pfd.Sysfd)
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if err != nil {
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return nil, err
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}
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fs.filetype = ft
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return fs, err
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}
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// stat implements both Stat and Lstat of a file.
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func stat(funcname, name string, createFileAttrs uint32) (FileInfo, error) {
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if len(name) == 0 {
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return nil, &PathError{funcname, name, syscall.Errno(syscall.ERROR_PATH_NOT_FOUND)}
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}
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if isNulName(name) {
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return &devNullStat, nil
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}
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namep, err := syscall.UTF16PtrFromString(fixLongPath(name))
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if err != nil {
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return nil, &PathError{funcname, name, err}
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}
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// Try GetFileAttributesEx first, because it is faster than CreateFile.
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// See https://golang.org/issues/19922#issuecomment-300031421 for details.
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var fa syscall.Win32FileAttributeData
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err = syscall.GetFileAttributesEx(namep, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
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if err == nil && fa.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
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// Not a symlink.
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fs := &fileStat{
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path: name,
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FileAttributes: fa.FileAttributes,
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CreationTime: fa.CreationTime,
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LastAccessTime: fa.LastAccessTime,
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LastWriteTime: fa.LastWriteTime,
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FileSizeHigh: fa.FileSizeHigh,
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FileSizeLow: fa.FileSizeLow,
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}
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// Gather full path to be used by os.SameFile later.
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if !isAbs(fs.path) {
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fs.path, err = syscall.FullPath(fs.path)
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if err != nil {
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return nil, &PathError{"FullPath", name, err}
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}
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}
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fs.name = basename(name)
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return fs, nil
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}
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// GetFileAttributesEx fails with ERROR_SHARING_VIOLATION error for
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// files, like c:\pagefile.sys. Use FindFirstFile for such files.
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if err == windows.ERROR_SHARING_VIOLATION {
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var fd syscall.Win32finddata
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sh, err := syscall.FindFirstFile(namep, &fd)
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if err != nil {
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return nil, &PathError{"FindFirstFile", name, err}
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}
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syscall.FindClose(sh)
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return newFileStatFromWin32finddata(&fd), nil
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}
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// Finally use CreateFile.
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h, err := syscall.CreateFile(namep, 0, 0, nil,
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syscall.OPEN_EXISTING, createFileAttrs, 0)
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if err != nil {
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return nil, &PathError{"CreateFile", name, err}
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}
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defer syscall.CloseHandle(h)
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return newFileStatFromGetFileInformationByHandle(name, h)
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}
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// statNolog implements Stat for Windows.
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func statNolog(name string) (FileInfo, error) {
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return stat("Stat", name, syscall.FILE_FLAG_BACKUP_SEMANTICS)
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}
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// lstatNolog implements Lstat for Windows.
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func lstatNolog(name string) (FileInfo, error) {
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attrs := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
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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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return stat("Lstat", name, attrs)
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}
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