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##=============================================================================
#
# Copyright (C) 2003, 2011 Alessandro Duca <alessandro.duca@gmail.com>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#=============================================================================
#
##=============================================================================
import sys
from io import BytesIO
import _yenc
from contextlib import contextmanager
E_ERROR = 64
E_CRC32 = 65
E_PARMS = 66
BIN_MASK = 0xffffffff
class Error(Exception):
""" Class for specific yenc errors
"""
def __init__(self, value="", code=E_ERROR):
self.value = value
def __str__(self):
return "yenc.Error: %s\n" % self.value
@contextmanager
def _checkArgsType(file_in, file_out, bytez):
""" Internal checkings, not to be used from outside this module.
"""
if bytez < 0:
raise Error("No. of bytes can't be negative", E_PARMS)
opened_in = None
opened_out = None
try:
if type(file_in) == str:
if file_in == "-":
if bytez == 0: raise Error("No. of bytes is 0 or not "
"specified while reading from stdin", E_PARMS)
try: # Python 3
file_in = sys.stdin.buffer
except AttributeError: # Python < 3
file_in = sys.stdin
else:
opened_in = open(file_in,"rb")
file_in = opened_in
if type(file_out) == str:
if file_out == "-":
try: # Python 3
file_out = sys.stdout.buffer
except AttributeError: # Python < 3
file_out = sys.stdout
else:
opened_out = open(file_out,"wb")
file_out = opened_out
yield file_in, file_out, bytez
finally:
if opened_out:
opened_out.close()
if opened_in:
opened_in.close()
def encode(file_in, file_out, bytez=0):
""" encode(file_in, file_out, bytez=0): write "bytez" encoded bytes from
file_in to file_out, if "bytez" is 0 encodes bytes until EOF.
The input file object must implement a read() method, which will be
passed a "size" parameter, and should always return a bytes() object,
even at EOF. The output file object must implement write() and
flush() methods. The write() method is passed a byte string and
should write all the data it is passed; no return value is required.
The flush() method need not accept any parameters or return a value.
Both io.BufferedIOBase objects and Python 2's file objects are
compatible.
"""
with _checkArgsType(file_in, file_out, bytez) as [file_in, file_out, bytez]:
encoded, crc32 = _yenc.encode(file_in, file_out, bytez)
return encoded, "%08x" % (crc32 ^ BIN_MASK)
def decode(file_in, file_out, bytez=0, crc_in=""):
""" decode(file_in, file_out, bytez=0): write "bytez" decoded bytes from
file_in to file_out, if "bytez" is 0 decodes bytes until EOF. Input
and output file objects must implement same interfaces as for
encode().
"""
with _checkArgsType(file_in, file_out, bytez) as [file_in, file_out, bytez]:
decoded, crc32 = _yenc.decode(file_in, file_out, bytez)
crc_hex = "%08x" % (crc32 ^ BIN_MASK)
if crc_in and crc_hex != crc_in.lower():
raise Error("crc32 error", E_CRC32)
else:
return decoded, crc_hex
class Encoder:
""" class Encoder: facility class for encoding one string at time
Constructor accepts an optional "output_file" argument, file must be opened in write mode.
When output_file is specified flush() will write the buffer content onto the
and close() will flush and close the file. After close() further calls to feed() will fail.
"""
def __init__(self, output_file = None):
self._buffer = BytesIO()
self._column = 0
self._output_file = output_file
self._crc = BIN_MASK
self._encoded = 0
self._feedable = True
def __del__(self):
if self._output_file is not None:
self.flush()
self.close()
def feed(self, data):
""" Encode some data and write the encoded data
into the internal buffer.
"""
if not self._feedable:
raise IOError("Encoding already terminated")
encoded, self._crc, self._column = _yenc.encode_string(data, self._crc, self._column)
self._encoded = self._encoded + len(encoded)
self._buffer.write(encoded)
return len(encoded)
def terminate(self):
""" Appends the terminal CRLF sequence to the encoded data.
Further calls to feed() will fail.
"""
self._buffer.write(b"\r\n")
self._feedable = False
def flush(self):
""" Writes the content of the internal buffer on output_file.
"""
if self._output_file is None:
raise ValueError("Output file is 'None'")
self._output_file.write(self._buffer.getvalue())
self._buffer = BytesIO()
def close(self):
""" Flushes and closes output_file.
The output buffer IS NOT automatically written to the file.
"""
if self._output_file is None:
raise ValueError("Output file is 'None'")
self._output_file.close()
self._output_file = None
self._feedable = False
def getEncoded(self):
""" Returns the data in the internal buffer.
"""
if self._output_file is not None:
raise ValueError("Output file is not 'None'")
return self._buffer.getvalue()
def getSize(self):
""" Returns the total number of encoded bytes (not the size of
the buffer).
"""
return self._encoded
def getCrc32(self):
""" Returns the calculated crc32 string for the clear data.
"""
return "%08x" % (self._crc ^ BIN_MASK)
class Decoder:
""" class Decoder: facility class for decoding one string at time
Constructor accepts an optional "output_file" argument, file must be opened in write mode.
When output_file is specified flush() will write the buffer content onto the
and close() will flush and close the file. After close() further calls to feed() will fail.
"""
def __init__(self, output_file = None):
self._buffer = BytesIO()
self._escape = 0
self._output_file = output_file
self._crc = BIN_MASK
self._decoded = 0
self._feedable = True
def __del__(self):
if self._output_file is not None:
self.flush()
self.close()
def feed(self, data):
""" Decode some data and write the decoded data
into the internal buffer.
"""
if not self._feedable:
raise IOError("Decoding already terminated")
decoded, self._crc, self._escape = _yenc.decode_string(data, self._crc, self._escape)
self._decoded = self._decoded + len(decoded)
self._buffer.write(decoded)
return len(decoded)
def flush(self):
""" Writes the content of the internal buffer on the file
passed as argument to the constructor.
"""
if self._output_file is None:
raise ValueError("Output file is 'None'")
self._output_file.write(self._buffer.getvalue())
self._buffer = BytesIO()
def close(self):
""" Flushes and closes output_file.
The output file is flushed before closing, further calls to feed() will fail.
"""
if self._output_file is None:
raise ValueError("Output file is 'None'")
self._output_file.close()
self._output_file = None
self._feedable = False
def getDecoded(self):
""" Returns the decoded data from the internal buffer.
If output_file is not None this is going to raise a ValueError.
"""
if self._output_file is not None:
raise ValueError("Output file is not 'None'")
return self._buffer.getvalue()
def getSize(self):
""" Returns the total number of decoded bytes (not the size of
the buffer).
"""
return self._decoded
def getCrc32(self):
""" Returns the calculated crc32 string for the decoded data.
"""
return "%08x" % (self._crc ^ BIN_MASK)
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