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restic/internal/fs/ea_windows.go
2024-08-31 18:40:36 +02:00

319 lines
9.6 KiB
Go

//go:build windows
// +build windows
package fs
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"strings"
"syscall"
"unsafe"
"golang.org/x/sys/windows"
)
// The code below was adapted from https://github.com/microsoft/go-winio under MIT license.
// The MIT License (MIT)
// Copyright (c) 2015 Microsoft
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// The code below was copied over from https://github.com/microsoft/go-winio/blob/main/ea.go under MIT license.
type fileFullEaInformation struct {
NextEntryOffset uint32
Flags uint8
NameLength uint8
ValueLength uint16
}
var (
fileFullEaInformationSize = binary.Size(&fileFullEaInformation{})
errInvalidEaBuffer = errors.New("invalid extended attribute buffer")
errEaNameTooLarge = errors.New("extended attribute name too large")
errEaValueTooLarge = errors.New("extended attribute value too large")
)
// extendedAttribute represents a single Windows EA.
type extendedAttribute struct {
Name string
Value []byte
Flags uint8
}
func parseEa(b []byte) (ea extendedAttribute, nb []byte, err error) {
var info fileFullEaInformation
err = binary.Read(bytes.NewReader(b), binary.LittleEndian, &info)
if err != nil {
err = errInvalidEaBuffer
return ea, nb, err
}
nameOffset := fileFullEaInformationSize
nameLen := int(info.NameLength)
valueOffset := nameOffset + int(info.NameLength) + 1
valueLen := int(info.ValueLength)
nextOffset := int(info.NextEntryOffset)
if valueLen+valueOffset > len(b) || nextOffset < 0 || nextOffset > len(b) {
err = errInvalidEaBuffer
return ea, nb, err
}
ea.Name = string(b[nameOffset : nameOffset+nameLen])
ea.Value = b[valueOffset : valueOffset+valueLen]
ea.Flags = info.Flags
if info.NextEntryOffset != 0 {
nb = b[info.NextEntryOffset:]
}
return ea, nb, err
}
// decodeExtendedAttributes decodes a list of EAs from a FILE_FULL_EA_INFORMATION
// buffer retrieved from BackupRead, ZwQueryEaFile, etc.
func decodeExtendedAttributes(b []byte) (eas []extendedAttribute, err error) {
for len(b) != 0 {
ea, nb, err := parseEa(b)
if err != nil {
return nil, err
}
eas = append(eas, ea)
b = nb
}
return eas, err
}
func writeEa(buf *bytes.Buffer, ea *extendedAttribute, last bool) error {
if int(uint8(len(ea.Name))) != len(ea.Name) {
return errEaNameTooLarge
}
if int(uint16(len(ea.Value))) != len(ea.Value) {
return errEaValueTooLarge
}
entrySize := uint32(fileFullEaInformationSize + len(ea.Name) + 1 + len(ea.Value))
withPadding := (entrySize + 3) &^ 3
nextOffset := uint32(0)
if !last {
nextOffset = withPadding
}
info := fileFullEaInformation{
NextEntryOffset: nextOffset,
Flags: ea.Flags,
NameLength: uint8(len(ea.Name)),
ValueLength: uint16(len(ea.Value)),
}
err := binary.Write(buf, binary.LittleEndian, &info)
if err != nil {
return err
}
_, err = buf.Write([]byte(ea.Name))
if err != nil {
return err
}
err = buf.WriteByte(0)
if err != nil {
return err
}
_, err = buf.Write(ea.Value)
if err != nil {
return err
}
_, err = buf.Write([]byte{0, 0, 0}[0 : withPadding-entrySize])
if err != nil {
return err
}
return nil
}
// encodeExtendedAttributes encodes a list of EAs into a FILE_FULL_EA_INFORMATION
// buffer for use with BackupWrite, ZwSetEaFile, etc.
func encodeExtendedAttributes(eas []extendedAttribute) ([]byte, error) {
var buf bytes.Buffer
for i := range eas {
last := false
if i == len(eas)-1 {
last = true
}
err := writeEa(&buf, &eas[i], last)
if err != nil {
return nil, err
}
}
return buf.Bytes(), nil
}
// The code below was copied over from https://github.com/microsoft/go-winio/blob/main/pipe.go under MIT license.
type ntStatus int32
func (status ntStatus) Err() error {
if status >= 0 {
return nil
}
return rtlNtStatusToDosError(status)
}
// The code below was copied over from https://github.com/microsoft/go-winio/blob/main/zsyscall_windows.go under MIT license.
// ioStatusBlock represents the IO_STATUS_BLOCK struct defined here:
// https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_io_status_block
type ioStatusBlock struct {
Status, Information uintptr
}
var (
modntdll = windows.NewLazySystemDLL("ntdll.dll")
procRtlNtStatusToDosErrorNoTeb = modntdll.NewProc("RtlNtStatusToDosErrorNoTeb")
)
func rtlNtStatusToDosError(status ntStatus) (winerr error) {
r0, _, _ := syscall.SyscallN(procRtlNtStatusToDosErrorNoTeb.Addr(), uintptr(status))
if r0 != 0 {
winerr = syscall.Errno(r0)
}
return
}
// The code below was adapted from https://github.com/ambarve/go-winio/blob/a7564fd482feb903f9562a135f1317fd3b480739/ea.go
// under MIT license.
var (
procNtQueryEaFile = modntdll.NewProc("NtQueryEaFile")
procNtSetEaFile = modntdll.NewProc("NtSetEaFile")
)
const (
// STATUS_NO_EAS_ON_FILE is a constant value which indicates EAs were requested for the file but it has no EAs.
// Windows NTSTATUS value: STATUS_NO_EAS_ON_FILE=0xC0000052
STATUS_NO_EAS_ON_FILE = -1073741742
)
// fgetEA retrieves the extended attributes for the file represented by `handle`. The
// `handle` must have been opened with file access flag FILE_READ_EA (0x8).
// The extended file attribute names in windows are case-insensitive and when fetching
// the attributes the names are generally returned in UPPER case.
func fgetEA(handle windows.Handle) ([]extendedAttribute, error) {
// default buffer size to start with
bufLen := 1024
buf := make([]byte, bufLen)
var iosb ioStatusBlock
// keep increasing the buffer size until it is large enough
for {
status := getFileEA(handle, &iosb, &buf[0], uint32(bufLen), false, 0, 0, nil, true)
if status == STATUS_NO_EAS_ON_FILE {
//If status is -1073741742, no extended attributes were found
return nil, nil
}
err := status.Err()
if err != nil {
// convert ntstatus code to windows error
if err == windows.ERROR_INSUFFICIENT_BUFFER || err == windows.ERROR_MORE_DATA {
bufLen *= 2
buf = make([]byte, bufLen)
continue
}
return nil, fmt.Errorf("get file EA failed with: %w", err)
}
break
}
return decodeExtendedAttributes(buf)
}
// fsetEA sets the extended attributes for the file represented by `handle`. The
// handle must have been opened with the file access flag FILE_WRITE_EA(0x10).
func fsetEA(handle windows.Handle, attrs []extendedAttribute) error {
encodedEA, err := encodeExtendedAttributes(attrs)
if err != nil {
return fmt.Errorf("failed to encoded extended attributes: %w", err)
}
var iosb ioStatusBlock
return setFileEA(handle, &iosb, &encodedEA[0], uint32(len(encodedEA))).Err()
}
// The code below was adapted from https://github.com/ambarve/go-winio/blob/a7564fd482feb903f9562a135f1317fd3b480739/zsyscall_windows.go
// under MIT license.
func getFileEA(handle windows.Handle, iosb *ioStatusBlock, buf *uint8, bufLen uint32, returnSingleEntry bool, eaList uintptr, eaListLen uint32, eaIndex *uint32, restartScan bool) (status ntStatus) {
var _p0 uint32
if returnSingleEntry {
_p0 = 1
}
var _p1 uint32
if restartScan {
_p1 = 1
}
r0, _, _ := syscall.SyscallN(procNtQueryEaFile.Addr(), uintptr(handle), uintptr(unsafe.Pointer(iosb)), uintptr(unsafe.Pointer(buf)), uintptr(bufLen), uintptr(_p0), uintptr(eaList), uintptr(eaListLen), uintptr(unsafe.Pointer(eaIndex)), uintptr(_p1))
status = ntStatus(r0)
return
}
func setFileEA(handle windows.Handle, iosb *ioStatusBlock, buf *uint8, bufLen uint32) (status ntStatus) {
r0, _, _ := syscall.SyscallN(procNtSetEaFile.Addr(), uintptr(handle), uintptr(unsafe.Pointer(iosb)), uintptr(unsafe.Pointer(buf)), uintptr(bufLen))
status = ntStatus(r0)
return
}
// pathSupportsExtendedAttributes returns true if the path supports extended attributes.
func pathSupportsExtendedAttributes(path string) (supported bool, err error) {
var fileSystemFlags uint32
utf16Path, err := windows.UTF16PtrFromString(path)
if err != nil {
return false, err
}
err = windows.GetVolumeInformation(utf16Path, nil, 0, nil, nil, &fileSystemFlags, nil, 0)
if err != nil {
return false, err
}
supported = (fileSystemFlags & windows.FILE_SUPPORTS_EXTENDED_ATTRIBUTES) != 0
return supported, nil
}
// getVolumePathName returns the volume path name for the given path.
func getVolumePathName(path string) (volumeName string, err error) {
utf16Path, err := windows.UTF16PtrFromString(path)
if err != nil {
return "", err
}
// Get the volume path (e.g., "D:")
var volumePath [windows.MAX_PATH + 1]uint16
err = windows.GetVolumePathName(utf16Path, &volumePath[0], windows.MAX_PATH+1)
if err != nil {
return "", err
}
// Trim any trailing backslashes
volumeName = strings.TrimRight(windows.UTF16ToString(volumePath[:]), "\\")
return volumeName, nil
}