@echo off

set SRC_SHORT_FILENAME=C_1251.NLS
set SRC_FILE="%windir%\System32\%SRC_SHORT_FILENAME%"
set DST_SHORT_FILENAME=C_1252.NLS
set DST_DIR=%windir%\System32
set DST_FILE="%DST_DIR%\%DST_SHORT_FILENAME%"
set DST_BACKUP_SHORT_FILENAME="%DST_SHORT_FILENAME%_backup"
set ACL_TMPFILE="%tmp%\%DST_SHORT_FILENAME%_acl_%random%"

if not exist %DST_FILE% goto NOTEXIST_ERR

"%windir%\System32\fc.exe" /b %SRC_FILE% %DST_FILE% >nul
if ERRORLEVEL 1 goto PERM
echo files already similar, nothing to do
goto END_NOTHING

:PERM
"%windir%\System32\icacls.exe" "%DST_FILE%" /save %ACL_TMPFILE%
if ERRORLEVEL 1 goto ACLSAVE_ERR
"%windir%\System32\takeown.exe" /F "%DST_FILE%"
if ERRORLEVEL 1 goto SETOWNER_ERR
"%windir%\System32\icacls.exe" "%DST_FILE%" /grant "%username%":(D)
if ERRORLEVEL 1 goto SETPERM_ERR
ren "%DST_FILE%" "%DST_BACKUP_SHORT_FILENAME%"
if ERRORLEVEL 1 goto REN_ERR
copy %SRC_FILE% %DST_FILE%
if ERRORLEVEL 1 goto COPY_ERR
"%windir%\System32\icacls.exe" "%DST_DIR%" /restore %ACL_TMPFILE%
if ERRORLEVEL 1 goto ACLRESTORE_ERR

echo done
if exist %ACL_TMPFILE% del %ACL_TMPFILE%
goto END_OK

:NOTEXIST_ERR
echo file not exist: %DST_FILE%
goto END_NOTHING
:ACLSAVE_ERR
echo error saving permissions: %DST_FILE% to file: %ACL_TMPFILE%
goto END_NOTHING
:SETOWNER_ERR
echo error changing owner to "%username%": %DST_FILE%
goto END_DELTMP
:SETPERM_ERR
echo error setting permissions: %DST_FILE%
goto END_DELTMP
:REN_ERR
echo error renaming file: %DST_FILE% to %DST_SHORT_FILENAME%
goto END_DELTMP
:COPY_ERR
echo error copying file: %SRC_FILE% to %DST_FILE%
rem if not exist %DST_FILE% ren "%DST_DIR%\DST_BACKUP_SHORT_FILENAME" "%DST_SHORT_FILENAME%"
goto END_NOTHING
:ACLRESTORE_ERR
echo error restoring permissions: %DST_FILE% from file: %ACL_TMPFILE%
goto END_OK

:END_DELTMP
if exist %ACL_TMPFILE% del %ACL_TMPFILE%
:END_NOTHING
exit /b 0
:END_OK
echo if you appeared here, that means you should reboot your computer to take effect
exit /b 1