mirror of https://github.com/cheat/cheat.git
132 lines
3.4 KiB
Go
132 lines
3.4 KiB
Go
//go:build windows
|
|
// +build windows
|
|
|
|
package winio
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"fmt"
|
|
"strings"
|
|
"unicode/utf16"
|
|
"unsafe"
|
|
)
|
|
|
|
const (
|
|
reparseTagMountPoint = 0xA0000003
|
|
reparseTagSymlink = 0xA000000C
|
|
)
|
|
|
|
type reparseDataBuffer struct {
|
|
ReparseTag uint32
|
|
ReparseDataLength uint16
|
|
Reserved uint16
|
|
SubstituteNameOffset uint16
|
|
SubstituteNameLength uint16
|
|
PrintNameOffset uint16
|
|
PrintNameLength uint16
|
|
}
|
|
|
|
// ReparsePoint describes a Win32 symlink or mount point.
|
|
type ReparsePoint struct {
|
|
Target string
|
|
IsMountPoint bool
|
|
}
|
|
|
|
// UnsupportedReparsePointError is returned when trying to decode a non-symlink or
|
|
// mount point reparse point.
|
|
type UnsupportedReparsePointError struct {
|
|
Tag uint32
|
|
}
|
|
|
|
func (e *UnsupportedReparsePointError) Error() string {
|
|
return fmt.Sprintf("unsupported reparse point %x", e.Tag)
|
|
}
|
|
|
|
// DecodeReparsePoint decodes a Win32 REPARSE_DATA_BUFFER structure containing either a symlink
|
|
// or a mount point.
|
|
func DecodeReparsePoint(b []byte) (*ReparsePoint, error) {
|
|
tag := binary.LittleEndian.Uint32(b[0:4])
|
|
return DecodeReparsePointData(tag, b[8:])
|
|
}
|
|
|
|
func DecodeReparsePointData(tag uint32, b []byte) (*ReparsePoint, error) {
|
|
isMountPoint := false
|
|
switch tag {
|
|
case reparseTagMountPoint:
|
|
isMountPoint = true
|
|
case reparseTagSymlink:
|
|
default:
|
|
return nil, &UnsupportedReparsePointError{tag}
|
|
}
|
|
nameOffset := 8 + binary.LittleEndian.Uint16(b[4:6])
|
|
if !isMountPoint {
|
|
nameOffset += 4
|
|
}
|
|
nameLength := binary.LittleEndian.Uint16(b[6:8])
|
|
name := make([]uint16, nameLength/2)
|
|
err := binary.Read(bytes.NewReader(b[nameOffset:nameOffset+nameLength]), binary.LittleEndian, &name)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &ReparsePoint{string(utf16.Decode(name)), isMountPoint}, nil
|
|
}
|
|
|
|
func isDriveLetter(c byte) bool {
|
|
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
|
|
}
|
|
|
|
// EncodeReparsePoint encodes a Win32 REPARSE_DATA_BUFFER structure describing a symlink or
|
|
// mount point.
|
|
func EncodeReparsePoint(rp *ReparsePoint) []byte {
|
|
// Generate an NT path and determine if this is a relative path.
|
|
var ntTarget string
|
|
relative := false
|
|
if strings.HasPrefix(rp.Target, `\\?\`) {
|
|
ntTarget = `\??\` + rp.Target[4:]
|
|
} else if strings.HasPrefix(rp.Target, `\\`) {
|
|
ntTarget = `\??\UNC\` + rp.Target[2:]
|
|
} else if len(rp.Target) >= 2 && isDriveLetter(rp.Target[0]) && rp.Target[1] == ':' {
|
|
ntTarget = `\??\` + rp.Target
|
|
} else {
|
|
ntTarget = rp.Target
|
|
relative = true
|
|
}
|
|
|
|
// The paths must be NUL-terminated even though they are counted strings.
|
|
target16 := utf16.Encode([]rune(rp.Target + "\x00"))
|
|
ntTarget16 := utf16.Encode([]rune(ntTarget + "\x00"))
|
|
|
|
size := int(unsafe.Sizeof(reparseDataBuffer{})) - 8
|
|
size += len(ntTarget16)*2 + len(target16)*2
|
|
|
|
tag := uint32(reparseTagMountPoint)
|
|
if !rp.IsMountPoint {
|
|
tag = reparseTagSymlink
|
|
size += 4 // Add room for symlink flags
|
|
}
|
|
|
|
data := reparseDataBuffer{
|
|
ReparseTag: tag,
|
|
ReparseDataLength: uint16(size),
|
|
SubstituteNameOffset: 0,
|
|
SubstituteNameLength: uint16((len(ntTarget16) - 1) * 2),
|
|
PrintNameOffset: uint16(len(ntTarget16) * 2),
|
|
PrintNameLength: uint16((len(target16) - 1) * 2),
|
|
}
|
|
|
|
var b bytes.Buffer
|
|
_ = binary.Write(&b, binary.LittleEndian, &data)
|
|
if !rp.IsMountPoint {
|
|
flags := uint32(0)
|
|
if relative {
|
|
flags |= 1
|
|
}
|
|
_ = binary.Write(&b, binary.LittleEndian, flags)
|
|
}
|
|
|
|
_ = binary.Write(&b, binary.LittleEndian, ntTarget16)
|
|
_ = binary.Write(&b, binary.LittleEndian, target16)
|
|
return b.Bytes()
|
|
}
|