# Demonstrates problem with gzip.GzipFile.flush()
#
# flush() is expected to output all pending data stored
# in internal buffers.
# gzip.GzipFile.flush() does perform a flush on its
# fileobj, but does not flush the state of its compressobj
# prior to the IO flush.
#
# 26 Jan 2005 - david.schnepper@verity.com

import cStringIO
import gzip
import sys

print "Python %s\n"%sys.version

uncompressed_data = "abc" * 1000
restored_data = ""

stringbuffer = cStringIO.StringIO()
gzip_file = gzip.GzipFile(mode="wb", fileobj = stringbuffer)

initial_output = stringbuffer.getvalue()[:]
gzip_file.write( uncompressed_data )
gzip_file.flush()

after_flush = stringbuffer.getvalue()[:]

if len(initial_output) >= len(after_flush):
    print "FAIL: Data has been written to GzipFile, and flush() has been invoked."
    print "      But no additional bytes are in the output stream."
    print "      This indicates that flush() did not flush the state of all internal buffers"
    print " len(original) = %d"%len(initial_output)
    print " len(after)    = %d"%len(after_flush)
    
    
gzip_file.close()
# It is OK for close() to write additional data

# Ensure the data can be restored.
after_close = stringbuffer.getvalue()[:]
in_file = cStringIO.StringIO(after_close)
restored_data = gzip.GzipFile(mode="rb", fileobj = in_file).read()

if restored_data != uncompressed_data:
    print "FAIL: uncompressed data does not match restored data"