import win32file, win32api, winerror
import os

def ReadCallback(input_buffer, data, buflen):
    fnamein, fnameout, f = data
    ## print fnamein, fnameout, buflen
    f.write(input_buffer)
    ## python 2.3 throws an error if return value is a plain int
    return winerror.ERROR_SUCCESS

def WriteCallback(output_buffer, data, buflen):
    fnamebackup, fnameout, f = data
    file_data=f.read(buflen)
    ## returning 0 as len terminates WriteEncryptedFileRaw
    output_len=len(file_data)
    output_buffer[:output_len]=file_data
    return winerror.ERROR_SUCCESS, output_len


tmp_dir=win32api.GetTempPath()
dst_dir=win32api.GetTempFileName(tmp_dir,'oef')[0]
os.remove(dst_dir)
os.mkdir(dst_dir)
print('Destination dir:', dst_dir)

## create an encrypted file
fname=win32api.GetTempFileName(dst_dir,'ref')[0]
print('orig file:',fname)
f=open(fname,'w')
f.write('xxxxxxxxxxxxxxxx\n'*32768)
f.close()
## add a couple of extra data streams
f=open(fname+':stream_y','w')
f.write('yyyyyyyyyyyyyyyy\n'*32768)
f.close()
f=open(fname+':stream_z','w')
f.write('zzzzzzzzzzzzzzzz\n'*32768)
f.close()
win32file.EncryptFile(fname)

## backup raw data of encrypted file
bkup_fname=win32api.GetTempFileName(dst_dir,'bef')[0]
print('backup file:', bkup_fname)
f=open(bkup_fname,'wb')
ctxt=win32file.OpenEncryptedFileRaw(fname,0)
try:
    win32file.ReadEncryptedFileRaw(ReadCallback, (fname,bkup_fname,f), ctxt)
finally:
    ## if context is not closed, file remains locked even if calling process is killed
    win32file.CloseEncryptedFileRaw(ctxt)
    f.close()

## restore data from backup to new encrypted file
dst_fname=win32api.GetTempFileName(dst_dir,'wef')[0]
print('restored file:', dst_fname)
f=open(bkup_fname,'rb')
ctxtout=win32file.OpenEncryptedFileRaw(dst_fname, win32file.CREATE_FOR_IMPORT)
try:
    win32file.WriteEncryptedFileRaw(WriteCallback, (bkup_fname,dst_fname,f), ctxtout)
finally:
    win32file.CloseEncryptedFileRaw(ctxtout)
    f.close()