syncthing/lib/fs/basicfs_windows.go

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// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
// +build windows
package fs
import (
"bytes"
"errors"
"fmt"
"os"
"path/filepath"
"strings"
"syscall"
"unsafe"
)
var errNotSupported = errors.New("symlinks not supported")
func (BasicFilesystem) SymlinksSupported() bool {
return false
}
func (BasicFilesystem) ReadSymlink(path string) (string, error) {
return "", errNotSupported
}
func (BasicFilesystem) CreateSymlink(target, name string) error {
return errNotSupported
}
// Required due to https://github.com/golang/go/issues/10900
func (f *BasicFilesystem) mkdirAll(path string, perm os.FileMode) error {
// Fast path: if we can tell whether path is a directory or file, stop with success or error.
dir, err := os.Stat(path)
if err == nil {
if dir.IsDir() {
return nil
}
return &os.PathError{
Op: "mkdir",
Path: path,
Err: syscall.ENOTDIR,
}
}
// Slow path: make sure parent exists and then call Mkdir for path.
i := len(path)
for i > 0 && IsPathSeparator(path[i-1]) { // Skip trailing path separator.
i--
}
j := i
for j > 0 && !IsPathSeparator(path[j-1]) { // Scan backward over element.
j--
}
if j > 1 {
// Create parent
parent := path[0 : j-1]
if parent != filepath.VolumeName(parent) {
err = f.mkdirAll(parent, perm)
if err != nil {
return err
}
}
}
// Parent now exists; invoke Mkdir and use its result.
err = os.Mkdir(path, perm)
if err != nil {
// Handle arguments like "foo/." by
// double-checking that directory doesn't exist.
dir, err1 := os.Lstat(path)
if err1 == nil && dir.IsDir() {
return nil
}
return err
}
return nil
}
func (f *BasicFilesystem) Unhide(name string) error {
name, err := f.rooted(name)
if err != nil {
return err
}
p, err := syscall.UTF16PtrFromString(name)
if err != nil {
return err
}
attrs, err := syscall.GetFileAttributes(p)
if err != nil {
return err
}
attrs &^= syscall.FILE_ATTRIBUTE_HIDDEN
return syscall.SetFileAttributes(p, attrs)
}
func (f *BasicFilesystem) Hide(name string) error {
name, err := f.rooted(name)
if err != nil {
return err
}
p, err := syscall.UTF16PtrFromString(name)
if err != nil {
return err
}
attrs, err := syscall.GetFileAttributes(p)
if err != nil {
return err
}
attrs |= syscall.FILE_ATTRIBUTE_HIDDEN
return syscall.SetFileAttributes(p, attrs)
}
func (f *BasicFilesystem) Roots() ([]string, error) {
kernel32, err := syscall.LoadDLL("kernel32.dll")
if err != nil {
return nil, err
}
getLogicalDriveStringsHandle, err := kernel32.FindProc("GetLogicalDriveStringsA")
if err != nil {
return nil, err
}
buffer := [1024]byte{}
bufferSize := uint32(len(buffer))
hr, _, _ := getLogicalDriveStringsHandle.Call(uintptr(unsafe.Pointer(&bufferSize)), uintptr(unsafe.Pointer(&buffer)))
if hr == 0 {
return nil, fmt.Errorf("Syscall failed")
}
var drives []string
parts := bytes.Split(buffer[:], []byte{0})
for _, part := range parts {
if len(part) == 0 {
break
}
drives = append(drives, string(part))
}
return drives, nil
}
// unrootedChecked returns the path relative to the folder root (same as
// unrooted). It panics if the given path is not a subpath and handles the
// special case when the given path is the folder root without a trailing
// pathseparator.
func (f *BasicFilesystem) unrootedChecked(absPath, root string) string {
absPath = f.resolveWin83(absPath)
lowerAbsPath := UnicodeLowercase(absPath)
lowerRoot := UnicodeLowercase(root)
if lowerAbsPath+string(PathSeparator) == lowerRoot {
return "."
}
if !strings.HasPrefix(lowerAbsPath, lowerRoot) {
panic(fmt.Sprintf("bug: Notify backend is processing a change outside of the filesystem root: f.root==%v, root==%v (lower), path==%v (lower)", f.root, lowerRoot, lowerAbsPath))
}
return rel(absPath, root)
}
func rel(path, prefix string) string {
lowerRel := strings.TrimPrefix(strings.TrimPrefix(UnicodeLowercase(path), UnicodeLowercase(prefix)), string(PathSeparator))
return path[len(path)-len(lowerRel):]
}
func (f *BasicFilesystem) resolveWin83(absPath string) string {
if !isMaybeWin83(absPath) {
return absPath
}
if in, err := syscall.UTF16FromString(absPath); err == nil {
out := make([]uint16, 4*len(absPath)) // *2 for UTF16 and *2 to double path length
if n, err := syscall.GetLongPathName(&in[0], &out[0], uint32(len(out))); err == nil {
if n <= uint32(len(out)) {
return syscall.UTF16ToString(out[:n])
}
out = make([]uint16, n)
if _, err = syscall.GetLongPathName(&in[0], &out[0], n); err == nil {
return syscall.UTF16ToString(out)
}
}
}
// Failed getting the long path. Return the part of the path which is
// already a long path.
lowerRoot := UnicodeLowercase(f.root)
for absPath = filepath.Dir(absPath); strings.HasPrefix(UnicodeLowercase(absPath), lowerRoot); absPath = filepath.Dir(absPath) {
if !isMaybeWin83(absPath) {
return absPath
}
}
return f.root
}
func isMaybeWin83(absPath string) bool {
if !strings.Contains(absPath, "~") {
return false
}
if strings.Contains(filepath.Dir(absPath), "~") {
return true
}
return strings.Contains(strings.TrimPrefix(filepath.Base(absPath), WindowsTempPrefix), "~")
}
func evalSymlinks(in string) (string, error) {
out, err := filepath.EvalSymlinks(in)
if err != nil && strings.HasPrefix(in, `\\?\`) {
// Try again without the `\\?\` prefix
out, err = filepath.EvalSymlinks(in[4:])
}
if err != nil {
return "", err
}
return longFilenameSupport(out), nil
}