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import io
import os
import struct
import tempfile
import unittest
import zstandard as zstd
from .common import (
NonClosingBytesIO,
CustomBytesIO,
)
def decompress_via_writer(data):
buffer = io.BytesIO()
dctx = zstd.ZstdDecompressor()
decompressor = dctx.stream_writer(buffer)
decompressor.write(data)
return buffer.getvalue()
class TestDecompressor_stream_writer(unittest.TestCase):
def test_io_api(self):
buffer = io.BytesIO()
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(buffer)
self.assertFalse(writer.closed)
self.assertFalse(writer.isatty())
self.assertFalse(writer.readable())
with self.assertRaises(io.UnsupportedOperation):
writer.__iter__()
with self.assertRaises(io.UnsupportedOperation):
writer.__next__()
with self.assertRaises(io.UnsupportedOperation):
writer.readline()
with self.assertRaises(io.UnsupportedOperation):
writer.readline(42)
with self.assertRaises(io.UnsupportedOperation):
writer.readline(size=42)
with self.assertRaises(io.UnsupportedOperation):
writer.readlines()
with self.assertRaises(io.UnsupportedOperation):
writer.readlines(42)
with self.assertRaises(io.UnsupportedOperation):
writer.readlines(hint=42)
with self.assertRaises(io.UnsupportedOperation):
writer.seek(0)
with self.assertRaises(io.UnsupportedOperation):
writer.seek(10, os.SEEK_SET)
self.assertFalse(writer.seekable())
with self.assertRaises(io.UnsupportedOperation):
writer.tell()
with self.assertRaises(io.UnsupportedOperation):
writer.truncate()
with self.assertRaises(io.UnsupportedOperation):
writer.truncate(42)
with self.assertRaises(io.UnsupportedOperation):
writer.truncate(size=42)
self.assertTrue(writer.writable())
with self.assertRaises(io.UnsupportedOperation):
writer.writelines([])
with self.assertRaises(io.UnsupportedOperation):
writer.read()
with self.assertRaises(io.UnsupportedOperation):
writer.read(42)
with self.assertRaises(io.UnsupportedOperation):
writer.read(size=42)
with self.assertRaises(io.UnsupportedOperation):
writer.readall()
with self.assertRaises(io.UnsupportedOperation):
writer.readinto(None)
with self.assertRaises(io.UnsupportedOperation):
writer.fileno()
def test_fileno_file(self):
with tempfile.TemporaryFile("wb") as tf:
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(tf)
self.assertEqual(writer.fileno(), tf.fileno())
def test_close(self):
foo = zstd.ZstdCompressor().compress(b"foo")
buffer = NonClosingBytesIO()
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(buffer)
writer.write(foo)
self.assertFalse(writer.closed)
self.assertFalse(buffer.closed)
writer.close()
self.assertTrue(writer.closed)
self.assertTrue(buffer.closed)
with self.assertRaisesRegex(ValueError, "stream is closed"):
writer.write(b"")
with self.assertRaisesRegex(ValueError, "stream is closed"):
writer.flush()
with self.assertRaisesRegex(ValueError, "stream is closed"):
with writer:
pass
self.assertEqual(buffer.getvalue(), b"foo")
# Context manager exit should close stream.
buffer = CustomBytesIO()
writer = dctx.stream_writer(buffer)
with writer:
writer.write(foo)
self.assertTrue(writer.closed)
self.assertTrue(buffer.closed)
self.assertEqual(buffer._flush_count, 0)
# Context manager exit should close stream if an exception raised.
buffer = CustomBytesIO()
writer = dctx.stream_writer(buffer)
with self.assertRaisesRegex(Exception, "ignore"):
with writer:
writer.write(foo)
raise Exception("ignore")
self.assertTrue(writer.closed)
self.assertTrue(buffer.closed)
self.assertEqual(buffer._flush_count, 0)
def test_close_closefd_false(self):
foo = zstd.ZstdCompressor().compress(b"foo")
buffer = NonClosingBytesIO()
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(buffer, closefd=False)
writer.write(foo)
self.assertFalse(writer.closed)
self.assertFalse(buffer.closed)
writer.close()
self.assertTrue(writer.closed)
self.assertFalse(buffer.closed)
with self.assertRaisesRegex(ValueError, "stream is closed"):
writer.write(b"")
with self.assertRaisesRegex(ValueError, "stream is closed"):
writer.flush()
with self.assertRaisesRegex(ValueError, "stream is closed"):
with writer:
pass
self.assertEqual(buffer.getvalue(), b"foo")
# Context manager exit should close stream.
buffer = CustomBytesIO()
writer = dctx.stream_writer(buffer, closefd=False)
with writer:
writer.write(foo)
self.assertTrue(writer.closed)
self.assertFalse(buffer.closed)
self.assertEqual(buffer._flush_count, 0)
# Context manager exit should close stream if an exception raised.
buffer = CustomBytesIO()
writer = dctx.stream_writer(buffer, closefd=False)
with self.assertRaisesRegex(Exception, "ignore"):
with writer:
writer.write(foo)
raise Exception("ignore")
self.assertTrue(writer.closed)
self.assertFalse(buffer.closed)
self.assertEqual(buffer._flush_count, 0)
def test_flush(self):
buffer = CustomBytesIO()
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(buffer)
writer.flush()
self.assertEqual(buffer._flush_count, 1)
writer.flush()
self.assertEqual(buffer._flush_count, 2)
def test_empty_roundtrip(self):
cctx = zstd.ZstdCompressor()
empty = cctx.compress(b"")
self.assertEqual(decompress_via_writer(empty), b"")
def test_input_types(self):
cctx = zstd.ZstdCompressor(level=1)
compressed = cctx.compress(b"foo")
mutable_array = bytearray(len(compressed))
mutable_array[:] = compressed
sources = [
memoryview(compressed),
bytearray(compressed),
mutable_array,
]
dctx = zstd.ZstdDecompressor()
for source in sources:
buffer = io.BytesIO()
decompressor = dctx.stream_writer(buffer)
decompressor.write(source)
self.assertEqual(buffer.getvalue(), b"foo")
buffer = io.BytesIO()
with dctx.stream_writer(buffer, closefd=False) as decompressor:
self.assertEqual(decompressor.write(source), len(source))
self.assertEqual(buffer.getvalue(), b"foo")
buffer = io.BytesIO()
writer = dctx.stream_writer(buffer, write_return_read=False)
self.assertEqual(writer.write(source), 3)
self.assertEqual(buffer.getvalue(), b"foo")
def test_large_roundtrip(self):
chunks = []
for i in range(255):
chunks.append(struct.Struct(">B").pack(i) * 16384)
orig = b"".join(chunks)
cctx = zstd.ZstdCompressor()
compressed = cctx.compress(orig)
self.assertEqual(decompress_via_writer(compressed), orig)
def test_multiple_calls(self):
chunks = []
for i in range(255):
for j in range(255):
chunks.append(struct.Struct(">B").pack(j) * i)
orig = b"".join(chunks)
cctx = zstd.ZstdCompressor()
compressed = cctx.compress(orig)
buffer = io.BytesIO()
dctx = zstd.ZstdDecompressor()
with dctx.stream_writer(buffer, closefd=False) as decompressor:
pos = 0
while pos < len(compressed):
pos2 = pos + 8192
decompressor.write(compressed[pos:pos2])
pos += 8192
self.assertEqual(buffer.getvalue(), orig)
# Again with write_return_read=False
buffer = io.BytesIO()
writer = dctx.stream_writer(buffer, write_return_read=False)
pos = 0
buffer_len = len(buffer.getvalue())
while pos < len(compressed):
pos2 = pos + 8192
chunk = compressed[pos:pos2]
self.assertEqual(
writer.write(chunk), len(buffer.getvalue()) - buffer_len
)
buffer_len = len(buffer.getvalue())
pos += 8192
self.assertEqual(buffer.getvalue(), orig)
def test_dictionary(self):
samples = []
for i in range(128):
samples.append(b"foo" * 64)
samples.append(b"bar" * 64)
samples.append(b"foobar" * 64)
d = zstd.train_dictionary(8192, samples)
orig = b"foobar" * 16384
buffer = io.BytesIO()
cctx = zstd.ZstdCompressor(dict_data=d)
with cctx.stream_writer(buffer, closefd=False) as compressor:
self.assertEqual(compressor.write(orig), len(orig))
compressed = buffer.getvalue()
buffer = io.BytesIO()
dctx = zstd.ZstdDecompressor(dict_data=d)
decompressor = dctx.stream_writer(buffer)
self.assertEqual(decompressor.write(compressed), len(compressed))
self.assertEqual(buffer.getvalue(), orig)
buffer = io.BytesIO()
with dctx.stream_writer(buffer, closefd=False) as decompressor:
self.assertEqual(decompressor.write(compressed), len(compressed))
self.assertEqual(buffer.getvalue(), orig)
def test_memory_size(self):
dctx = zstd.ZstdDecompressor()
buffer = io.BytesIO()
decompressor = dctx.stream_writer(buffer)
size = decompressor.memory_size()
self.assertGreater(size, 90000)
with dctx.stream_writer(buffer) as decompressor:
size = decompressor.memory_size()
self.assertGreater(size, 90000)
def test_write_size(self):
source = zstd.ZstdCompressor().compress(b"foobarfoobar")
dest = CustomBytesIO()
dctx = zstd.ZstdDecompressor()
with dctx.stream_writer(
dest, write_size=1, closefd=False
) as decompressor:
s = struct.Struct(">B")
for c in source:
if not isinstance(c, str):
c = s.pack(c)
decompressor.write(c)
self.assertEqual(dest.getvalue(), b"foobarfoobar")
self.assertEqual(dest._write_count, len(dest.getvalue()))
def test_write_exception(self):
frame = zstd.ZstdCompressor().compress(b"foo" * 1024)
b = CustomBytesIO()
b.write_exception = IOError("write")
dctx = zstd.ZstdDecompressor()
writer = dctx.stream_writer(b)
with self.assertRaisesRegex(IOError, "write"):
writer.write(frame)
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