def test_empty(self):
with self.assertRaisesRegex(
zstd.ZstdError,
"could not determine frame header size: Src size "
"is incorrect",
):
zstd.frame_header_size(b"")
def main(args):
with open(args.input_file, 'rb') as f:
if args.is_zst:
# The footer has been pre-stripped for us,
# so we only need to decompress using the standard ZST library function
decompress_stream_to_output_file(args, f)
else:
# We need to strip the footer from the rec file
# before feeding it to the ZST library function
in_memory_copy = io.BytesIO(f.read())
buffer = in_memory_copy.getbuffer()
actual_last_bytes = buffer[-len(last_bytes):]
if actual_last_bytes != last_bytes:
display_warning(
args, f"WARNING: This doesn't look like a .rec file. "
f"The last {len(last_bytes)} bytes didn't match the expected value.\n"
f"Expected Value:\t\t{bytes_to_hex_string(actual_last_bytes)}\n"
f"Actual Value:\t\t{bytes_to_hex_string(last_bytes)}")
# Find the last frame in the ZST file
last_zst_header_addr = find_last_zst_header(buffer)
if last_zst_header_addr is None:
display_warning(
args,
f"WARNING: This doesn't look like a .rec file. Couldn't find any ZST"
f" magic number bytes")
last_zst_header_bytes = bytes(
buffer[last_zst_header_addr:last_zst_header_addr + 25])
frame_header_size = zstandard.frame_header_size(
last_zst_header_bytes)
# Read through each block in this last frame to find the location of the end of the file
block_params = zst_utils.parse_block_header(
last_zst_header_bytes[frame_header_size:frame_header_size + 3])
next_block_addr = last_zst_header_addr + frame_header_size + 3 + block_params.block_size
while not block_params.last_block:
block_params = zst_utils.parse_block_header(
bytes(buffer[next_block_addr:next_block_addr + 3]))
next_block_addr += 3 + block_params.block_size
# The next byte after the last block in the last frame is outside of the ZST file, giving us the length
size_of_zst_file = next_block_addr
# Only grab the first portion of the file (which is simply a ZST file)
in_memory_copy.seek(0)
zst_file_in_memory = io.BytesIO(
in_memory_copy.read(size_of_zst_file))
# Decompress and write to output file
decompress_stream_to_output_file(args, zst_file_in_memory)
def test_basic(self):
# It doesn't matter that it isn't a valid frame.
self.assertEqual(zstd.frame_header_size(b"long enough but no magic"),
6)
def test_too_small(self):
with self.assertRaisesRegexp(
zstd.ZstdError,
'could not determine frame header size: Src size '
'is incorrect'):
zstd.frame_header_size(b'foob')
def test_basic(self):
# It doesn't matter that it isn't a valid frame.
self.assertEqual(zstd.frame_header_size(b'long enough but no magic'), 6)
def test_too_small(self):
with self.assertRaisesRegexp(
zstd.ZstdError, 'could not determine frame header size: Src size '
'is incorrect'):
zstd.frame_header_size(b'foob')