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