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Diffstat (limited to 'cvs2svn_lib/apple_single_filter.py')
| -rw-r--r-- | cvs2svn_lib/apple_single_filter.py | 292 |
1 files changed, 0 insertions, 292 deletions
diff --git a/cvs2svn_lib/apple_single_filter.py b/cvs2svn_lib/apple_single_filter.py deleted file mode 100644 index 95fa9cb..0000000 --- a/cvs2svn_lib/apple_single_filter.py +++ /dev/null @@ -1,292 +0,0 @@ -# (Be in -*- python -*- mode.) -# -# ==================================================================== -# Copyright (c) 2007-2008 CollabNet. All rights reserved. -# -# This software is licensed as described in the file COPYING, which -# you should have received as part of this distribution. The terms -# are also available at http://subversion.tigris.org/license-1.html. -# If newer versions of this license are posted there, you may use a -# newer version instead, at your option. -# -# This software consists of voluntary contributions made by many -# individuals. For exact contribution history, see the revision -# history and logs, available at http://cvs2svn.tigris.org/. -# ==================================================================== - -"""A stream filter for extracting the data fork from AppleSingle data. - -Some Macintosh CVS clients store resource fork data along with the -contents of the file (called the data fork) by encoding both in an -'AppleSingle' data stream before storing them to CVS. This file -contains a stream filter for extracting the data fork from such data -streams. (Any other forks are discarded.) - -See the following for some random information about this format and -how it is used by Macintosh CVS clients: - - http://users.phg-online.de/tk/netatalk/doc/Apple/v1/ - http://rfc.net/rfc1740.html - http://ximbiot.com/cvs/cvshome/cyclic/cvs/dev-mac.html - http://www.maccvs.org/faq.html#resfiles - http://www.heilancoo.net/MacCVSClient/MacCVSClientDoc/storage-formats.html - -""" - - -import struct -from cStringIO import StringIO - - -class AppleSingleFormatError(IOError): - """The stream was not in correct AppleSingle format.""" - - pass - - -class AppleSingleIncorrectMagicError(AppleSingleFormatError): - """The file didn't start with the correct magic number.""" - - def __init__(self, data_read, eof): - AppleSingleFormatError.__init__(self) - self.data_read = data_read - self.eof = eof - - -class AppleSingleEOFError(AppleSingleFormatError): - """EOF was reached where AppleSingle doesn't allow it.""" - - pass - - -class AppleSingleFilter(object): - """A stream that reads the data fork from an AppleSingle stream. - - If the constructor discovers that the file is not a legitimate - AppleSingle stream, then it raises an AppleSingleFormatError. In - the special case that the magic number is incorrect, it raises - AppleSingleIncorrectMagicError with data_read set to the data that - have been read so far from the input stream. (This allows the - caller the option to fallback to treating the input stream as a - normal binary data stream.)""" - - # The header is: - # - # Magic number 4 bytes - # Version number 4 bytes - # File system or filler 16 bytes - # Number of entries 2 bytes - magic_struct = '>i' - magic_len = struct.calcsize(magic_struct) - - # The part of the header after the magic number: - rest_of_header_struct = '>i16sH' - rest_of_header_len = struct.calcsize(rest_of_header_struct) - - # Each entry is: - # - # Entry ID 4 bytes - # Offset 4 bytes - # Length 4 bytes - entry_struct = '>iii' - entry_len = struct.calcsize(entry_struct) - - apple_single_magic = 0x00051600 - apple_single_version_1 = 0x00010000 - apple_single_version_2 = 0x00020000 - apple_single_filler = '\0' * 16 - - apple_single_data_fork_entry_id = 1 - - def __init__(self, stream): - self.stream = stream - - # Check for the AppleSingle magic number: - s = self._read_exactly(self.magic_len) - if len(s) < self.magic_len: - raise AppleSingleIncorrectMagicError(s, True) - - (magic,) = struct.unpack(self.magic_struct, s) - if magic != self.apple_single_magic: - raise AppleSingleIncorrectMagicError(s, False) - - # Read the rest of the header: - s = self._read_exactly(self.rest_of_header_len) - if len(s) < self.rest_of_header_len: - raise AppleSingleEOFError('AppleSingle header incomplete') - - (version, filler, num_entries) = \ - struct.unpack(self.rest_of_header_struct, s) - - if version == self.apple_single_version_1: - self._prepare_apple_single_v1_file(num_entries) - elif version == self.apple_single_version_2: - if filler != self.apple_single_filler: - raise AppleSingleFormatError('Incorrect filler') - self._prepare_apple_single_v2_file(num_entries) - else: - raise AppleSingleFormatError('Unknown AppleSingle version') - - def _read_exactly(self, size): - """Read and return exactly SIZE characters from the stream. - - This method is to deal with the fact that stream.read(size) is - allowed to return less than size characters. If EOF is reached - before SIZE characters have been read, return the characters that - have been read so far.""" - - retval = [] - length_remaining = size - while length_remaining > 0: - s = self.stream.read(length_remaining) - if not s: - break - retval.append(s) - length_remaining -= len(s) - - return ''.join(retval) - - def _prepare_apple_single_file(self, num_entries): - entries = self._read_exactly(num_entries * self.entry_len) - if len(entries) < num_entries * self.entry_len: - raise AppleSingleEOFError('Incomplete entries list') - - for i in range(num_entries): - entry = entries[i * self.entry_len : (i + 1) * self.entry_len] - (entry_id, offset, length) = struct.unpack(self.entry_struct, entry) - if entry_id == self.apple_single_data_fork_entry_id: - break - else: - raise AppleSingleFormatError('No data fork found') - - # The data fork is located at [offset : offset + length]. Read up - # to the start of the data: - n = offset - self.magic_len - self.rest_of_header_len - len(entries) - if n < 0: - raise AppleSingleFormatError('Invalid offset to AppleSingle data fork') - - max_chunk_size = 65536 - while n > 0: - s = self.stream.read(min(n, max_chunk_size)) - if not s: - raise AppleSingleEOFError( - 'Offset to AppleSingle data fork past end of file' - ) - n -= len(s) - - self.length_remaining = length - - def _prepare_apple_single_v1_file(self, num_entries): - self._prepare_apple_single_file(num_entries) - - def _prepare_apple_single_v2_file(self, num_entries): - self._prepare_apple_single_file(num_entries) - - def read(self, size=-1): - if size == 0 or self.length_remaining == 0: - return '' - elif size < 0: - s = self._read_exactly(self.length_remaining) - if len(s) < self.length_remaining: - raise AppleSingleEOFError('AppleSingle data fork truncated') - self.length_remaining = 0 - return s - else: - # The length of this read is allowed to be shorter than the - # requested size: - s = self.stream.read(min(size, self.length_remaining)) - if not s: - raise AppleSingleEOFError() - self.length_remaining -= len(s) - return s - - def close(self): - self.stream.close() - self.stream = None - - -class CompoundStream(object): - """A stream that reads from a series of streams, one after the other.""" - - def __init__(self, *streams): - self.streams = list(streams) - self.stream_index = 0 - - def read(self, size=-1): - if size < 0: - retval = [] - while self.stream_index < len(self.streams): - retval.append(self.streams[self.stream_index].read()) - self.stream_index += 1 - return ''.join(retval) - else: - while self.stream_index < len(self.streams): - s = self.streams[self.stream_index].read(size) - if s: - # This may not be the full size requested, but that is OK: - return s - else: - # That stream was empty; proceed to the next stream: - self.stream_index += 1 - - # No streams are left: - return '' - - def close(self): - for stream in self.streams: - stream.close() - self.streams = None - - -def get_maybe_apple_single_stream(stream): - """Treat STREAM as AppleSingle if possible; otherwise treat it literally. - - If STREAM is in AppleSingle format, then return a stream that will - output the data fork of the original stream. Otherwise, return a - stream that will output the original file contents literally. - - Be careful not to read from STREAM after it has already hit EOF.""" - - try: - return AppleSingleFilter(stream) - except AppleSingleIncorrectMagicError, e: - # This is OK; the file is not AppleSingle, so we read it normally: - string_io = StringIO(e.data_read) - if e.eof: - # The original stream already reached EOF, so the part already - # read contains the complete file contents: - return string_io - else: - # The stream needs to output the part already read followed by - # whatever hasn't been read of the original stream: - return CompoundStream(string_io, stream) - - -if __name__ == '__main__': - # For fun and testing, allow use of this file as a pipe if it is - # invoked as a script. Specifically, if stdin is in AppleSingle - # format, then output only its data fork; otherwise, output it - # unchanged. - # - # This might not work on systems where sys.stdin is opened in text - # mode. - # - # Remember to set PYTHONPATH to point to the main cvs2svn directory. - - import sys - - #CHUNK_SIZE = -1 - CHUNK_SIZE = 100 - - f = get_maybe_apple_single_stream(sys.stdin) - - if CHUNK_SIZE < 0: - sys.stdout.write(f.read()) - else: - while True: - s = f.read(CHUNK_SIZE) - if not s: - break - sys.stdout.write(s) - - |