/usr/lib/python3.5/_compression.py is in libpython3.5-stdlib 3.5.1-10.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 | """Internal classes used by the gzip, lzma and bz2 modules"""
import io
BUFFER_SIZE = io.DEFAULT_BUFFER_SIZE # Compressed data read chunk size
class BaseStream(io.BufferedIOBase):
"""Mode-checking helper functions."""
def _check_not_closed(self):
if self.closed:
raise ValueError("I/O operation on closed file")
def _check_can_read(self):
if not self.readable():
raise io.UnsupportedOperation("File not open for reading")
def _check_can_write(self):
if not self.writable():
raise io.UnsupportedOperation("File not open for writing")
def _check_can_seek(self):
if not self.readable():
raise io.UnsupportedOperation("Seeking is only supported "
"on files open for reading")
if not self.seekable():
raise io.UnsupportedOperation("The underlying file object "
"does not support seeking")
class DecompressReader(io.RawIOBase):
"""Adapts the decompressor API to a RawIOBase reader API"""
def readable(self):
return True
def __init__(self, fp, decomp_factory, trailing_error=(), **decomp_args):
self._fp = fp
self._eof = False
self._pos = 0 # Current offset in decompressed stream
# Set to size of decompressed stream once it is known, for SEEK_END
self._size = -1
# Save the decompressor factory and arguments.
# If the file contains multiple compressed streams, each
# stream will need a separate decompressor object. A new decompressor
# object is also needed when implementing a backwards seek().
self._decomp_factory = decomp_factory
self._decomp_args = decomp_args
self._decompressor = self._decomp_factory(**self._decomp_args)
# Exception class to catch from decompressor signifying invalid
# trailing data to ignore
self._trailing_error = trailing_error
def close(self):
self._decompressor = None
return super().close()
def seekable(self):
return self._fp.seekable()
def readinto(self, b):
with memoryview(b) as view, view.cast("B") as byte_view:
data = self.read(len(byte_view))
byte_view[:len(data)] = data
return len(data)
def read(self, size=-1):
if size < 0:
return self.readall()
if not size or self._eof:
return b""
data = None # Default if EOF is encountered
# Depending on the input data, our call to the decompressor may not
# return any data. In this case, try again after reading another block.
while True:
if self._decompressor.eof:
rawblock = (self._decompressor.unused_data or
self._fp.read(BUFFER_SIZE))
if not rawblock:
break
# Continue to next stream.
self._decompressor = self._decomp_factory(
**self._decomp_args)
try:
data = self._decompressor.decompress(rawblock, size)
except self._trailing_error:
# Trailing data isn't a valid compressed stream; ignore it.
break
else:
if self._decompressor.needs_input:
rawblock = self._fp.read(BUFFER_SIZE)
if not rawblock:
raise EOFError("Compressed file ended before the "
"end-of-stream marker was reached")
else:
rawblock = b""
data = self._decompressor.decompress(rawblock, size)
if data:
break
if not data:
self._eof = True
self._size = self._pos
return b""
self._pos += len(data)
return data
# Rewind the file to the beginning of the data stream.
def _rewind(self):
self._fp.seek(0)
self._eof = False
self._pos = 0
self._decompressor = self._decomp_factory(**self._decomp_args)
def seek(self, offset, whence=io.SEEK_SET):
# Recalculate offset as an absolute file position.
if whence == io.SEEK_SET:
pass
elif whence == io.SEEK_CUR:
offset = self._pos + offset
elif whence == io.SEEK_END:
# Seeking relative to EOF - we need to know the file's size.
if self._size < 0:
while self.read(io.DEFAULT_BUFFER_SIZE):
pass
offset = self._size + offset
else:
raise ValueError("Invalid value for whence: {}".format(whence))
# Make it so that offset is the number of bytes to skip forward.
if offset < self._pos:
self._rewind()
else:
offset -= self._pos
# Read and discard data until we reach the desired position.
while offset > 0:
data = self.read(min(io.DEFAULT_BUFFER_SIZE, offset))
if not data:
break
offset -= len(data)
return self._pos
def tell(self):
"""Return the current file position."""
return self._pos
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