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binhex.py
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"""Macintosh binhex compression/decompression. easy interface: binhex(inputfilename, outputfilename) hexbin(inputfilename, outputfilename) """ # # Jack Jansen, CWI, August 1995. # # The module is supposed to be as compatible as possible. Especially the # easy interface should work "as expected" on any platform. # XXXX Note: currently, textfiles appear in mac-form on all platforms. # We seem to lack a simple character-translate in python. # (we should probably use ISO-Latin-1 on all but the mac platform). # XXXX The simple routines are too simple: they expect to hold the complete # files in-core. Should be fixed. # XXXX It would be nice to handle AppleDouble format on unix # (for servers serving macs). # XXXX I don't understand what happens when you get 0x90 times the same byte on # input. The resulting code (xx 90 90) would appear to be interpreted as an # escaped *value* of 0x90. All coders I've seen appear to ignore this nicety... # import io import os import struct import binascii __all__ = ["binhex","hexbin","Error"] class Error(Exception): pass # States (what have we written) _DID_HEADER = 0 _DID_DATA = 1 # Various constants REASONABLY_LARGE = 32768 # Minimal amount we pass the rle-coder LINELEN = 64 RUNCHAR = b"\x90" # # This code is no longer byte-order dependent class FInfo: def __init__(self): self.Type = '????' self.Creator = '????' self.Flags = 0 def getfileinfo(name): finfo = FInfo() with io.open(name, 'rb') as fp: # Quick check for textfile data = fp.read(512) if 0 not in data: finfo.Type = 'TEXT' fp.seek(0, 2) dsize = fp.tell() dir, file = os.path.split(name) file = file.replace(':', '-', 1) return file, finfo, dsize, 0 class openrsrc: def __init__(self, *args): pass def read(self, *args): return b'' def write(self, *args): pass def close(self): pass class _Hqxcoderengine: """Write data to the coder in 3-byte chunks""" def __init__(self, ofp): self.ofp = ofp self.data = b'' self.hqxdata = b'' self.linelen = LINELEN - 1 def write(self, data): self.data = self.data + data datalen = len(self.data) todo = (datalen // 3) * 3 data = self.data[:todo] self.data = self.data[todo:] if not data: return self.hqxdata = self.hqxdata + binascii.b2a_hqx(data) self._flush(0) def _flush(self, force): first = 0 while first <= len(self.hqxdata) - self.linelen: last = first + self.linelen self.ofp.write(self.hqxdata[first:last] + b'\n') self.linelen = LINELEN first = last self.hqxdata = self.hqxdata[first:] if force: self.ofp.write(self.hqxdata + b':\n') def close(self): if self.data: self.hqxdata = self.hqxdata + binascii.b2a_hqx(self.data) self._flush(1) self.ofp.close() del self.ofp class _Rlecoderengine: """Write data to the RLE-coder in suitably large chunks""" def __init__(self, ofp): self.ofp = ofp self.data = b'' def write(self, data): self.data = self.data + data if len(self.data) < REASONABLY_LARGE: return rledata = binascii.rlecode_hqx(self.data) self.ofp.write(rledata) self.data = b'' def close(self): if self.data: rledata = binascii.rlecode_hqx(self.data) self.ofp.write(rledata) self.ofp.close() del self.ofp class BinHex: def __init__(self, name_finfo_dlen_rlen, ofp): name, finfo, dlen, rlen = name_finfo_dlen_rlen close_on_error = False if isinstance(ofp, str): ofname = ofp ofp = io.open(ofname, 'wb') close_on_error = True try: ofp.write(b'(This file must be converted with BinHex 4.0)\r\r:') hqxer = _Hqxcoderengine(ofp) self.ofp = _Rlecoderengine(hqxer) self.crc = 0 if finfo is None: finfo = FInfo() self.dlen = dlen self.rlen = rlen self._writeinfo(name, finfo) self.state = _DID_HEADER except: if close_on_error: ofp.close() raise def _writeinfo(self, name, finfo): nl = len(name) if nl > 63: raise Error('Filename too long') d = bytes([nl]) + name.encode("latin-1") + b'\0' tp, cr = finfo.Type, finfo.Creator if isinstance(tp, str): tp = tp.encode("latin-1") if isinstance(cr, str): cr = cr.encode("latin-1") d2 = tp + cr # Force all structs to be packed with big-endian d3 = struct.pack('>h', finfo.Flags) d4 = struct.pack('>ii', self.dlen, self.rlen) info = d + d2 + d3 + d4 self._write(info) self._writecrc() def _write(self, data): self.crc = binascii.crc_hqx(data, self.crc) self.ofp.write(data) def _writecrc(self): # XXXX Should this be here?? # self.crc = binascii.crc_hqx('\0\0', self.crc) if self.crc < 0: fmt = '>h' else: fmt = '>H' self.ofp.write(struct.pack(fmt, self.crc)) self.crc = 0 def write(self, data): if self.state != _DID_HEADER: raise Error('Writing data at the wrong time') self.dlen = self.dlen - len(data) self._write(data) def close_data(self): if self.dlen != 0: raise Error('Incorrect data size, diff=%r' % (self.rlen,)) self._writecrc() self.state = _DID_DATA def write_rsrc(self, data): if self.state < _DID_DATA: self.close_data() if self.state != _DID_DATA: raise Error('Writing resource data at the wrong time') self.rlen = self.rlen - len(data) self._write(data) def close(self): if self.state is None: return try: if self.state < _DID_DATA: self.close_data() if self.state != _DID_DATA: raise Error('Close at the wrong time') if self.rlen != 0: raise Error("Incorrect resource-datasize, diff=%r" % (self.rlen,)) self._writecrc() finally: self.state = None ofp = self.ofp del self.ofp ofp.close() def binhex(inp, out): """binhex(infilename, outfilename): create binhex-encoded copy of a file""" finfo = getfileinfo(inp) ofp = BinHex(finfo, out) with io.open(inp, 'rb') as ifp: # XXXX Do textfile translation on non-mac systems while True: d = ifp.read(128000) if not d: break ofp.write(d) ofp.close_data() ifp = openrsrc(inp, 'rb') while True: d = ifp.read(128000) if not d: break ofp.write_rsrc(d) ofp.close() ifp.close() class _Hqxdecoderengine: """Read data via the decoder in 4-byte chunks""" def __init__(self, ifp): self.ifp = ifp self.eof = 0 def read(self, totalwtd): """Read at least wtd bytes (or until EOF)""" decdata = b'' wtd = totalwtd # # The loop here is convoluted, since we don't really now how # much to decode: there may be newlines in the incoming data. while wtd > 0: if self.eof: return decdata wtd = ((wtd + 2) // 3) * 4 data = self.ifp.read(wtd) # # Next problem: there may not be a complete number of # bytes in what we pass to a2b. Solve by yet another # loop. # while True: try: decdatacur, self.eof = binascii.a2b_hqx(data) break except binascii.Incomplete: pass newdata = self.ifp.read(1) if not newdata: raise Error('Premature EOF on binhex file') data = data + newdata decdata = decdata + decdatacur wtd = totalwtd - len(decdata) if not decdata and not self.eof: raise Error('Premature EOF on binhex file') return decdata def close(self): self.ifp.close() class _Rledecoderengine: """Read data via the RLE-coder""" def __init__(self, ifp): self.ifp = ifp self.pre_buffer = b'' self.post_buffer = b'' self.eof = 0 def read(self, wtd): if wtd > len(self.post_buffer): self._fill(wtd - len(self.post_buffer)) rv = self.post_buffer[:wtd] self.post_buffer = self.post_buffer[wtd:] return rv def _fill(self, wtd): self.pre_buffer = self.pre_buffer + self.ifp.read(wtd + 4) if self.ifp.eof: self.post_buffer = self.post_buffer + \ binascii.rledecode_hqx(self.pre_buffer) self.pre_buffer = b'' return # # Obfuscated code ahead. We have to take care that we don't # end up with an orphaned RUNCHAR later on. So, we keep a couple # of bytes in the buffer, depending on what the end of # the buffer looks like: # '\220\0\220' - Keep 3 bytes: repeated \220 (escaped as \220\0) # '?\220' - Keep 2 bytes: repeated something-else # '\220\0' - Escaped \220: Keep 2 bytes. # '?\220?' - Complete repeat sequence: decode all # otherwise: keep 1 byte. # mark = len(self.pre_buffer) if self.pre_buffer[-3:] == RUNCHAR + b'\0' + RUNCHAR: mark = mark - 3 elif self.pre_buffer[-1:] == RUNCHAR: mark = mark - 2 elif self.pre_buffer[-2:] == RUNCHAR + b'\0': mark = mark - 2 elif self.pre_buffer[-2:-1] == RUNCHAR: pass # Decode all else: mark = mark - 1 self.post_buffer = self.post_buffer + \ binascii.rledecode_hqx(self.pre_buffer[:mark]) self.pre_buffer = self.pre_buffer[mark:] def close(self): self.ifp.close() class HexBin: def __init__(self, ifp): if isinstance(ifp, str): ifp = io.open(ifp, 'rb') # # Find initial colon. # while True: ch = ifp.read(1) if not ch: raise Error("No binhex data found") # Cater for \r\n terminated lines (which show up as \n\r, hence # all lines start with \r) if ch == b'\r': continue if ch == b':': break hqxifp = _Hqxdecoderengine(ifp) self.ifp = _Rledecoderengine(hqxifp) self.crc = 0 self._readheader() def _read(self, len): data = self.ifp.read(len) self.crc = binascii.crc_hqx(data, self.crc) return data def _checkcrc(self): filecrc = struct.unpack('>h', self.ifp.read(2))[0] & 0xffff #self.crc = binascii.crc_hqx('\0\0', self.crc) # XXXX Is this needed?? self.crc = self.crc & 0xffff if filecrc != self.crc: raise Error('CRC error, computed %x, read %x' % (self.crc, filecrc)) self.crc = 0 def _readheader(self): len = self._read(1) fname = self._read(ord(len)) rest = self._read(1 + 4 + 4 + 2 + 4 + 4) self._checkcrc() type = rest[1:5] creator = rest[5:9] flags = struct.unpack('>h', rest[9:11])[0] self.dlen = struct.unpack('>l', rest[11:15])[0] self.rlen = struct.unpack('>l', rest[15:19])[0] self.FName = fname self.FInfo = FInfo() self.FInfo.Creator = creator self.FInfo.Type = type self.FInfo.Flags = flags self.state = _DID_HEADER def read(self, *n): if self.state != _DID_HEADER: raise Error('Read data at wrong time') if n: n = n[0] n = min(n, self.dlen) else: n = self.dlen rv = b'' while len(rv) < n: rv = rv + self._read(n-len(rv)) self.dlen = self.dlen - n return rv def close_data(self): if self.state != _DID_HEADER: raise Error('close_data at wrong time') if self.dlen: dummy = self._read(self.dlen) self._checkcrc() self.state = _DID_DATA def read_rsrc(self, *n): if self.state == _DID_HEADER: self.close_data() if self.state != _DID_DATA: raise Error('Read resource data at wrong time') if n: n = n[0] n = min(n, self.rlen) else: n = self.rlen self.rlen = self.rlen - n return self._read(n) def close(self): if self.state is None: return try: if self.rlen: dummy = self.read_rsrc(self.rlen) self._checkcrc() finally: self.state = None self.ifp.close() def hexbin(inp, out): """hexbin(infilename, outfilename) - Decode binhexed file""" ifp = HexBin(inp) finfo = ifp.FInfo if not out: out = ifp.FName with io.open(out, 'wb') as ofp: # XXXX Do translation on non-mac systems while True: d = ifp.read(128000) if not d: break ofp.write(d) ifp.close_data() d = ifp.read_rsrc(128000) if d: ofp = openrsrc(out, 'wb') ofp.write(d) while True: d = ifp.read_rsrc(128000) if not d: break ofp.write(d) ofp.close() ifp.close()