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mirror of https://git.zx2c4.com/wireguard-windows synced 2024-11-10 16:59:18 +00:00
wireguard-windows/conf/filewriter_windows.go
Jason A. Donenfeld 6ed37f30f5 global: bump date
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-01-06 17:28:13 +01:00

91 lines
2.4 KiB
Go

/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019-2022 WireGuard LLC. All Rights Reserved.
*/
package conf
import (
"crypto/rand"
"encoding/hex"
"path/filepath"
"sync/atomic"
"unsafe"
"golang.org/x/sys/windows"
)
var encryptedFileSd unsafe.Pointer
func randomFileName() string {
var randBytes [32]byte
_, err := rand.Read(randBytes[:])
if err != nil {
panic(err)
}
return hex.EncodeToString(randBytes[:]) + ".tmp"
}
func writeLockedDownFile(destination string, overwrite bool, contents []byte) error {
var err error
sa := &windows.SecurityAttributes{Length: uint32(unsafe.Sizeof(windows.SecurityAttributes{}))}
sa.SecurityDescriptor = (*windows.SECURITY_DESCRIPTOR)(atomic.LoadPointer(&encryptedFileSd))
if sa.SecurityDescriptor == nil {
sa.SecurityDescriptor, err = windows.SecurityDescriptorFromString("O:SYG:SYD:PAI(A;;FA;;;SY)(A;;SD;;;BA)")
if err != nil {
return err
}
atomic.StorePointer(&encryptedFileSd, unsafe.Pointer(sa.SecurityDescriptor))
}
destination16, err := windows.UTF16FromString(destination)
if err != nil {
return err
}
tmpDestination := filepath.Join(filepath.Dir(destination), randomFileName())
tmpDestination16, err := windows.UTF16PtrFromString(tmpDestination)
if err != nil {
return err
}
handle, err := windows.CreateFile(tmpDestination16, windows.GENERIC_WRITE|windows.DELETE, windows.FILE_SHARE_READ, sa, windows.CREATE_ALWAYS, windows.FILE_ATTRIBUTE_NORMAL, 0)
if err != nil {
return err
}
defer windows.CloseHandle(handle)
deleteIt := func() {
yes := byte(1)
windows.SetFileInformationByHandle(handle, windows.FileDispositionInfo, &yes, 1)
}
n, err := windows.Write(handle, contents)
if err != nil {
deleteIt()
return err
}
if n != len(contents) {
deleteIt()
return windows.ERROR_IO_INCOMPLETE
}
fileRenameInfo := &struct {
replaceIfExists byte
rootDirectory windows.Handle
fileNameLength uint32
fileName [windows.MAX_PATH]uint16
}{replaceIfExists: func() byte {
if overwrite {
return 1
} else {
return 0
}
}(), fileNameLength: uint32(len(destination16) - 1)}
if len(destination16) > len(fileRenameInfo.fileName) {
deleteIt()
return windows.ERROR_BUFFER_OVERFLOW
}
copy(fileRenameInfo.fileName[:], destination16[:])
err = windows.SetFileInformationByHandle(handle, windows.FileRenameInfo, (*byte)(unsafe.Pointer(fileRenameInfo)), uint32(unsafe.Sizeof(*fileRenameInfo)))
if err != nil {
deleteIt()
return err
}
return nil
}