gzip.py

import sys
import shutil
import struct
import random
import time
import datetime
 
import zlib
from io import BytesIO
import io

def randomstring(length=0):
    return "test".encode("utf-8")

def write32u(output, value):
    # The L format writes the bit pattern correctly whether signed
    # or unsigned.
    output.write(struct.pack("<L", value))

crc = zlib.crc32(b"")
size = 0
f = io.BytesIO()
f.seek(0)

f.write(b'\037\213') #header
f.write(b'\010')                 # compression method
f.write(chr(8).encode('latin-1'))
write32u(f, int(time.time()))
f.write(b'\002')
f.write(b'\377')
f.write("filename.json".encode('latin-1') + b'\000')

compress = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS, zlib.DEF_MEM_LEVEL, 0)
data = b''

for i in range(1000):
    rs = randomstring(20)
    data += compress.compress(rs)
    crc = zlib.crc32(rs, crc)
    size += len(rs)

flu = compress.flush()
data += flu

f.write(data)
write32u(f, crc)
write32u(f, size & 0xffffffff)

length = f.tell()
f.seek(0)
with open("some111.txt.gz", "wb") as fle:
    shutil.copyfileobj(f, fle, length)

f.close()