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