all: Convert folders to use filesystem abstraction

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4228

lib/fs/basicfs_windows.go

@@ -0,0 +1,165 @@
+// 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"
+	"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(path, target string) error {
+	return errNotSupported
+}
+
+// MkdirAll creates a directory named path, along with any necessary parents,
+// and returns nil, or else returns an error.
+// The permission bits perm are used for all directories that MkdirAll creates.
+// If path is already a directory, MkdirAll does nothing and returns nil.
+func (f *BasicFilesystem) MkdirAll(path string, perm FileMode) error {
+	path, err := f.rooted(path)
+	if err != nil {
+		return err
+	}
+
+	return f.mkdirAll(path, os.FileMode(perm))
+}
+
+// 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 = os.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
+}