circuitpython/tests/extmod/deflate_decompress.py

try:
    # Check if deflate is available.
    import deflate
    import io
except ImportError:
    print("SKIP")
    raise SystemExit

# zlib.compress(b'micropython hello world hello world micropython', wbits=-9)
data_raw = b'\xcb\xcdL.\xca/\xa8,\xc9\xc8\xcfS\xc8H\xcd\xc9\xc9W(\xcf/\xcaIAa\xe7"\xd4\x00\x00'
# zlib.compress(b'micropython hello world hello world micropython', wbits=9)
data_zlib = b'\x18\x95\xcb\xcdL.\xca/\xa8,\xc9\xc8\xcfS\xc8H\xcd\xc9\xc9W(\xcf/\xcaIAa\xe7"\xd4\x00\x00\xbc\xfa\x12\x91'
# zlib.compress(b'micropython hello world hello world micropython', wbits=25)
data_gzip = b'\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x03\xcb\xcdL.\xca/\xa8,\xc9\xc8\xcfS\xc8H\xcd\xc9\xc9W(\xcf/\xcaIAa\xe7"\xd4\x00\x00"\xeb\xc4\x98/\x00\x00\x00'

# compress(b'hello' + bytearray(300) + b'hello', format=deflate.RAW, 5)
data_wbits_5 = b"\xcbH\xcd\xc9\xc9g\x18\xe9\x00\x08\x88\x95\xcfH\xcd\xc9\xc9\x07\x00"
# compress(b'hello' + bytearray(300) + b'hello', format=deflate.RAW, 6)
data_wbits_6 = b"\xcbH\xcd\xc9\xc9g\x18\xe9\x00\x08\x88\xd5\x9f\x91\x9a\x93\x93\x0f\x00"
# compress(b'hello' + bytearray(300) + b'hello', format=deflate.RAW, 8)
data_wbits_8 = b"\xcbH\xcd\xc9\xc9g\x18\xe9\x00\x08\x88\xf5\x7fFjNN>\x00"
# compress(b'hello' + bytearray(2000) + b'hello', format=deflate.RAW, 10)
data_wbits_10 = b"\xcbH\xcd\xc9\xc9g\x18\xe9\x00\x08Fz\x18\x00\xc3`\xa4'\x03`2\x18\xe99\x01\x98\x13Fz\xfe\x07\xe6\xff\x91\x9e\xff\x81\xf9\x7f\xa4\xe7\x7f`\xfe\x1f\xba\xf9?#5''\x1f\x00"


def decompress(data, *args):
    buf = io.BytesIO(data)
    with deflate.DeflateIO(buf, *args) as g:
        return g.read()


def decompress_error(data, *args):
    try:
        decompress(data, *args)
    except OSError:
        print("OSError")
    except EOFError:
        print("EOFError")
    except ValueError:
        print("ValueError")


# Basic handling of format and detection.
print(decompress(data_raw, deflate.RAW))
print(decompress(data_zlib, deflate.ZLIB))
print(decompress(data_gzip, deflate.GZIP))
print(decompress(data_zlib))  # detect zlib/gzip.
print(decompress(data_gzip))  # detect zlib/gzip.

decompress_error(data_raw)  # cannot detect zlib/gzip from raw stream
decompress_error(data_raw, deflate.ZLIB)
decompress_error(data_raw, deflate.GZIP)
decompress_error(data_zlib, deflate.RAW)
decompress_error(data_zlib, deflate.GZIP)
decompress_error(data_gzip, deflate.RAW)
decompress_error(data_gzip, deflate.ZLIB)

# Invalid data stream.
decompress_error(b"abcef", deflate.RAW)

# Invalid block type. final-block, block-type=3.
decompress_error(b"\x07", deflate.RAW)

# Truncated stream.
decompress_error(data_raw[:10], deflate.RAW)

# Partial reads.
buf = io.BytesIO(data_zlib)
with deflate.DeflateIO(buf) as g:
    print(buf.seek(0, 1))  # verify stream is not read until first read of the DeflateIO stream.
    print(g.read(1))
    print(buf.seek(0, 1))  # verify that only the minimal amount is read from the source
    print(g.read(1))
    print(buf.seek(0, 1))
    print(g.read(2))
    print(buf.seek(0, 1))
    print(g.read())
    print(buf.seek(0, 1))
    print(g.read(1))
    print(buf.seek(0, 1))
    print(g.read())

# Invalid zlib checksum (+ length for gzip). Note: only checksum errors are
# currently detected, see the end of uzlib_uncompress_chksum().
decompress_error(data_zlib[:-4] + b"\x00\x00\x00\x00")
decompress_error(data_gzip[:-8] + b"\x00\x00\x00\x00\x00\x00\x00\x00")
decompress_error(data_zlib[:-4] + b"\x00\x00\x00\x00", deflate.ZLIB)
decompress_error(data_gzip[:-8] + b"\x00\x00\x00\x00\x00\x00\x00\x00", deflate.GZIP)

# Reading from a closed underlying stream.
b = io.BytesIO(data_raw)
g = deflate.DeflateIO(b, deflate.RAW)
g.read(4)
b.close()
try:
    g.read(4)
except ValueError:
    print("ValueError")

# Reading from a closed DeflateIO.
b = io.BytesIO(data_raw)
g = deflate.DeflateIO(b, deflate.RAW)
g.read(4)
g.close()
try:
    g.read(4)
except OSError:
    print("OSError")

# Gzip header with extra flags (FCOMMENT FNAME FEXTRA FHCRC) enabled.
data_gzip_header_extra = b"\x1f\x8b\x08\x1e}\x9a\x9bd\x02\x00\x00\x00\x00\x00\x00\xff\xcb\xcdL.\xca/\xa8,\xc9\xc8\xcf\x03\x00\xf2KF>\x0b\x00\x00\x00"
print(decompress(data_gzip_header_extra))

# Test patterns.
PATTERNS_ZLIB = [
    # Packed results produced by CPy's zlib.compress()
    (b"0", b"x\x9c3\x00\x00\x001\x001"),
    (b"a", b"x\x9cK\x04\x00\x00b\x00b"),
    (b"0" * 100, b"x\x9c30\xa0=\x00\x00\xb3q\x12\xc1"),
    (
        bytes(range(64)),
        b"x\x9cc`dbfaec\xe7\xe0\xe4\xe2\xe6\xe1\xe5\xe3\x17\x10\x14\x12\x16\x11\x15\x13\x97\x90\x94\x92\x96\x91\x95\x93WPTRVQUS\xd7\xd0\xd4\xd2\xd6\xd1\xd5\xd370426153\xb7\xb0\xb4\xb2\xb6\xb1\xb5\xb3\x07\x00\xaa\xe0\x07\xe1",
    ),
    (b"hello", b"x\x01\x01\x05\x00\xfa\xffhello\x06,\x02\x15"),  # compression level 0
    # adaptive/dynamic huffman tree
    (
        b"13371813150|13764518736|12345678901",
        b"x\x9c\x05\xc1\x81\x01\x000\x04\x04\xb1\x95\\\x1f\xcfn\x86o\x82d\x06Qq\xc8\x9d\xc5X}<e\xb5g\x83\x0f\x89X\x07\xab",
    ),
    # dynamic Huffman tree with "case 17" (repeat code for 3-10 times)
    (
        b">I}\x00\x951D>I}\x00\x951D>I}\x00\x951D>I}\x00\x951D",
        b"x\x9c\x05\xc11\x01\x00\x00\x00\x010\x95\x14py\x84\x12C_\x9bR\x8cV\x8a\xd1J1Z)F\x1fw`\x089",
    ),
]
for unpacked, packed in PATTERNS_ZLIB:
    print(decompress(packed) == unpacked)
    print(decompress(packed, deflate.ZLIB) == unpacked)

# Older version's of CPython's zlib module still included the checksum and length (as if it were a zlib/gzip stream).
# Make sure there're no problem decompressing this.
data_raw_with_footer = data_raw + b"\x00\x00\x00\x00\x00\x00\x00\x00"
print(decompress(data_raw_with_footer, deflate.RAW))

# Valid wbits values.
decompress_error(data_wbits_5, deflate.RAW, -1)
print(len(decompress(data_wbits_5, deflate.RAW, 0)))
decompress_error(data_wbits_5, deflate.RAW, 1)
decompress_error(data_wbits_5, deflate.RAW, 4)
for i in range(5, 16):
    print(len(decompress(data_wbits_5, deflate.RAW, i)))
decompress_error(data_wbits_5, deflate.RAW, 16)

# Invalid values for format.
decompress_error(data_raw, -1)
decompress_error(data_raw, 5)

# Data that requires a higher wbits value.
decompress_error(data_wbits_6, deflate.RAW, 5)
print(len(decompress(data_wbits_6, deflate.RAW, 6)))
print(len(decompress(data_wbits_6, deflate.RAW, 7)))
decompress_error(data_wbits_8, deflate.RAW, 7)
print(len(decompress(data_wbits_8, deflate.RAW, 8)))
print(len(decompress(data_wbits_8, deflate.RAW, 9)))
decompress_error(data_wbits_10, deflate.RAW)
decompress_error(data_wbits_10, deflate.RAW, 9)
print(len(decompress(data_wbits_10, deflate.RAW, 10)))

# zlib header sets the size, so works with wbits unset or wbits >= 10.
data_wbits_10_zlib = b"(\x91\xcbH\xcd\xc9\xc9g\x18\xe9\x00\x08Fz\x18\x00\xc3`\xa4'\x03`2\x18\xe99\x01\x98\x13Fz\xfe\x07\xe6\xff\x91\x9e\xff\x81\xf9\x7f\xa4\xe7\x7f`\xfe\x1f\xba\xf9?#5''\x1f\x00[\xbc\x04)"
print(len(decompress(data_wbits_10_zlib, deflate.ZLIB)))
decompress_error(data_wbits_10_zlib, deflate.ZLIB, 9)
print(len(decompress(data_wbits_10_zlib, deflate.ZLIB, 10)))
print(len(decompress(data_wbits_10_zlib)))