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1"""Macintosh binhex compression/decompression.
2
3easy interface:
4binhex(inputfilename, outputfilename)
5hexbin(inputfilename, outputfilename)
6"""
7
8#
9# Jack Jansen, CWI, August 1995.
10#
11# The module is supposed to be as compatible as possible. Especially the
12# easy interface should work "as expected" on any platform.
13# XXXX Note: currently, textfiles appear in mac-form on all platforms.
14# We seem to lack a simple character-translate in python.
15# (we should probably use ISO-Latin-1 on all but the mac platform).
16# XXXX The simple routines are too simple: they expect to hold the complete
17# files in-core. Should be fixed.
18# XXXX It would be nice to handle AppleDouble format on unix
19# (for servers serving macs).
20# XXXX I don't understand what happens when you get 0x90 times the same byte on
21# input. The resulting code (xx 90 90) would appear to be interpreted as an
22# escaped *value* of 0x90. All coders I've seen appear to ignore this nicety...
23#
24import io
25import os
26import struct
27import binascii
28
29__all__ = ["binhex","hexbin","Error"]
30
31class Error(Exception):
32    pass
33
34# States (what have we written)
35_DID_HEADER = 0
36_DID_DATA = 1
37
38# Various constants
39REASONABLY_LARGE = 32768  # Minimal amount we pass the rle-coder
40LINELEN = 64
41RUNCHAR = b"\x90"
42
43#
44# This code is no longer byte-order dependent
45
46
47class FInfo:
48    def __init__(self):
49        self.Type = '????'
50        self.Creator = '????'
51        self.Flags = 0
52
53def getfileinfo(name):
54    finfo = FInfo()
55    with io.open(name, 'rb') as fp:
56        # Quick check for textfile
57        data = fp.read(512)
58        if 0 not in data:
59            finfo.Type = 'TEXT'
60        fp.seek(0, 2)
61        dsize = fp.tell()
62    dir, file = os.path.split(name)
63    file = file.replace(':', '-', 1)
64    return file, finfo, dsize, 0
65
66class openrsrc:
67    def __init__(self, *args):
68        pass
69
70    def read(self, *args):
71        return b''
72
73    def write(self, *args):
74        pass
75
76    def close(self):
77        pass
78
79class _Hqxcoderengine:
80    """Write data to the coder in 3-byte chunks"""
81
82    def __init__(self, ofp):
83        self.ofp = ofp
84        self.data = b''
85        self.hqxdata = b''
86        self.linelen = LINELEN - 1
87
88    def write(self, data):
89        self.data = self.data + data
90        datalen = len(self.data)
91        todo = (datalen // 3) * 3
92        data = self.data[:todo]
93        self.data = self.data[todo:]
94        if not data:
95            return
96        self.hqxdata = self.hqxdata + binascii.b2a_hqx(data)
97        self._flush(0)
98
99    def _flush(self, force):
100        first = 0
101        while first <= len(self.hqxdata) - self.linelen:
102            last = first + self.linelen
103            self.ofp.write(self.hqxdata[first:last] + b'\n')
104            self.linelen = LINELEN
105            first = last
106        self.hqxdata = self.hqxdata[first:]
107        if force:
108            self.ofp.write(self.hqxdata + b':\n')
109
110    def close(self):
111        if self.data:
112            self.hqxdata = self.hqxdata + binascii.b2a_hqx(self.data)
113        self._flush(1)
114        self.ofp.close()
115        del self.ofp
116
117class _Rlecoderengine:
118    """Write data to the RLE-coder in suitably large chunks"""
119
120    def __init__(self, ofp):
121        self.ofp = ofp
122        self.data = b''
123
124    def write(self, data):
125        self.data = self.data + data
126        if len(self.data) < REASONABLY_LARGE:
127            return
128        rledata = binascii.rlecode_hqx(self.data)
129        self.ofp.write(rledata)
130        self.data = b''
131
132    def close(self):
133        if self.data:
134            rledata = binascii.rlecode_hqx(self.data)
135            self.ofp.write(rledata)
136        self.ofp.close()
137        del self.ofp
138
139class BinHex:
140    def __init__(self, name_finfo_dlen_rlen, ofp):
141        name, finfo, dlen, rlen = name_finfo_dlen_rlen
142        close_on_error = False
143        if isinstance(ofp, str):
144            ofname = ofp
145            ofp = io.open(ofname, 'wb')
146            close_on_error = True
147        try:
148            ofp.write(b'(This file must be converted with BinHex 4.0)\r\r:')
149            hqxer = _Hqxcoderengine(ofp)
150            self.ofp = _Rlecoderengine(hqxer)
151            self.crc = 0
152            if finfo is None:
153                finfo = FInfo()
154            self.dlen = dlen
155            self.rlen = rlen
156            self._writeinfo(name, finfo)
157            self.state = _DID_HEADER
158        except:
159            if close_on_error:
160                ofp.close()
161            raise
162
163    def _writeinfo(self, name, finfo):
164        nl = len(name)
165        if nl > 63:
166            raise Error('Filename too long')
167        d = bytes([nl]) + name.encode("latin-1") + b'\0'
168        tp, cr = finfo.Type, finfo.Creator
169        if isinstance(tp, str):
170            tp = tp.encode("latin-1")
171        if isinstance(cr, str):
172            cr = cr.encode("latin-1")
173        d2 = tp + cr
174
175        # Force all structs to be packed with big-endian
176        d3 = struct.pack('>h', finfo.Flags)
177        d4 = struct.pack('>ii', self.dlen, self.rlen)
178        info = d + d2 + d3 + d4
179        self._write(info)
180        self._writecrc()
181
182    def _write(self, data):
183        self.crc = binascii.crc_hqx(data, self.crc)
184        self.ofp.write(data)
185
186    def _writecrc(self):
187        # XXXX Should this be here??
188        # self.crc = binascii.crc_hqx('\0\0', self.crc)
189        if self.crc < 0:
190            fmt = '>h'
191        else:
192            fmt = '>H'
193        self.ofp.write(struct.pack(fmt, self.crc))
194        self.crc = 0
195
196    def write(self, data):
197        if self.state != _DID_HEADER:
198            raise Error('Writing data at the wrong time')
199        self.dlen = self.dlen - len(data)
200        self._write(data)
201
202    def close_data(self):
203        if self.dlen != 0:
204            raise Error('Incorrect data size, diff=%r' % (self.rlen,))
205        self._writecrc()
206        self.state = _DID_DATA
207
208    def write_rsrc(self, data):
209        if self.state < _DID_DATA:
210            self.close_data()
211        if self.state != _DID_DATA:
212            raise Error('Writing resource data at the wrong time')
213        self.rlen = self.rlen - len(data)
214        self._write(data)
215
216    def close(self):
217        if self.state is None:
218            return
219        try:
220            if self.state < _DID_DATA:
221                self.close_data()
222            if self.state != _DID_DATA:
223                raise Error('Close at the wrong time')
224            if self.rlen != 0:
225                raise Error("Incorrect resource-datasize, diff=%r" % (self.rlen,))
226            self._writecrc()
227        finally:
228            self.state = None
229            ofp = self.ofp
230            del self.ofp
231            ofp.close()
232
233def binhex(inp, out):
234    """binhex(infilename, outfilename): create binhex-encoded copy of a file"""
235    finfo = getfileinfo(inp)
236    ofp = BinHex(finfo, out)
237
238    with io.open(inp, 'rb') as ifp:
239        # XXXX Do textfile translation on non-mac systems
240        while True:
241            d = ifp.read(128000)
242            if not d: break
243            ofp.write(d)
244        ofp.close_data()
245
246    ifp = openrsrc(inp, 'rb')
247    while True:
248        d = ifp.read(128000)
249        if not d: break
250        ofp.write_rsrc(d)
251    ofp.close()
252    ifp.close()
253
254class _Hqxdecoderengine:
255    """Read data via the decoder in 4-byte chunks"""
256
257    def __init__(self, ifp):
258        self.ifp = ifp
259        self.eof = 0
260
261    def read(self, totalwtd):
262        """Read at least wtd bytes (or until EOF)"""
263        decdata = b''
264        wtd = totalwtd
265        #
266        # The loop here is convoluted, since we don't really now how
267        # much to decode: there may be newlines in the incoming data.
268        while wtd > 0:
269            if self.eof: return decdata
270            wtd = ((wtd + 2) // 3) * 4
271            data = self.ifp.read(wtd)
272            #
273            # Next problem: there may not be a complete number of
274            # bytes in what we pass to a2b. Solve by yet another
275            # loop.
276            #
277            while True:
278                try:
279                    decdatacur, self.eof = binascii.a2b_hqx(data)
280                    break
281                except binascii.Incomplete:
282                    pass
283                newdata = self.ifp.read(1)
284                if not newdata:
285                    raise Error('Premature EOF on binhex file')
286                data = data + newdata
287            decdata = decdata + decdatacur
288            wtd = totalwtd - len(decdata)
289            if not decdata and not self.eof:
290                raise Error('Premature EOF on binhex file')
291        return decdata
292
293    def close(self):
294        self.ifp.close()
295
296class _Rledecoderengine:
297    """Read data via the RLE-coder"""
298
299    def __init__(self, ifp):
300        self.ifp = ifp
301        self.pre_buffer = b''
302        self.post_buffer = b''
303        self.eof = 0
304
305    def read(self, wtd):
306        if wtd > len(self.post_buffer):
307            self._fill(wtd - len(self.post_buffer))
308        rv = self.post_buffer[:wtd]
309        self.post_buffer = self.post_buffer[wtd:]
310        return rv
311
312    def _fill(self, wtd):
313        self.pre_buffer = self.pre_buffer + self.ifp.read(wtd + 4)
314        if self.ifp.eof:
315            self.post_buffer = self.post_buffer + \
316                binascii.rledecode_hqx(self.pre_buffer)
317            self.pre_buffer = b''
318            return
319
320        #
321        # Obfuscated code ahead. We have to take care that we don't
322        # end up with an orphaned RUNCHAR later on. So, we keep a couple
323        # of bytes in the buffer, depending on what the end of
324        # the buffer looks like:
325        # '\220\0\220' - Keep 3 bytes: repeated \220 (escaped as \220\0)
326        # '?\220' - Keep 2 bytes: repeated something-else
327        # '\220\0' - Escaped \220: Keep 2 bytes.
328        # '?\220?' - Complete repeat sequence: decode all
329        # otherwise: keep 1 byte.
330        #
331        mark = len(self.pre_buffer)
332        if self.pre_buffer[-3:] == RUNCHAR + b'\0' + RUNCHAR:
333            mark = mark - 3
334        elif self.pre_buffer[-1:] == RUNCHAR:
335            mark = mark - 2
336        elif self.pre_buffer[-2:] == RUNCHAR + b'\0':
337            mark = mark - 2
338        elif self.pre_buffer[-2:-1] == RUNCHAR:
339            pass # Decode all
340        else:
341            mark = mark - 1
342
343        self.post_buffer = self.post_buffer + \
344            binascii.rledecode_hqx(self.pre_buffer[:mark])
345        self.pre_buffer = self.pre_buffer[mark:]
346
347    def close(self):
348        self.ifp.close()
349
350class HexBin:
351    def __init__(self, ifp):
352        if isinstance(ifp, str):
353            ifp = io.open(ifp, 'rb')
354        #
355        # Find initial colon.
356        #
357        while True:
358            ch = ifp.read(1)
359            if not ch:
360                raise Error("No binhex data found")
361            # Cater for \r\n terminated lines (which show up as \n\r, hence
362            # all lines start with \r)
363            if ch == b'\r':
364                continue
365            if ch == b':':
366                break
367
368        hqxifp = _Hqxdecoderengine(ifp)
369        self.ifp = _Rledecoderengine(hqxifp)
370        self.crc = 0
371        self._readheader()
372
373    def _read(self, len):
374        data = self.ifp.read(len)
375        self.crc = binascii.crc_hqx(data, self.crc)
376        return data
377
378    def _checkcrc(self):
379        filecrc = struct.unpack('>h', self.ifp.read(2))[0] & 0xffff
380        #self.crc = binascii.crc_hqx('\0\0', self.crc)
381        # XXXX Is this needed??
382        self.crc = self.crc & 0xffff
383        if filecrc != self.crc:
384            raise Error('CRC error, computed %x, read %x'
385                        % (self.crc, filecrc))
386        self.crc = 0
387
388    def _readheader(self):
389        len = self._read(1)
390        fname = self._read(ord(len))
391        rest = self._read(1 + 4 + 4 + 2 + 4 + 4)
392        self._checkcrc()
393
394        type = rest[1:5]
395        creator = rest[5:9]
396        flags = struct.unpack('>h', rest[9:11])[0]
397        self.dlen = struct.unpack('>l', rest[11:15])[0]
398        self.rlen = struct.unpack('>l', rest[15:19])[0]
399
400        self.FName = fname
401        self.FInfo = FInfo()
402        self.FInfo.Creator = creator
403        self.FInfo.Type = type
404        self.FInfo.Flags = flags
405
406        self.state = _DID_HEADER
407
408    def read(self, *n):
409        if self.state != _DID_HEADER:
410            raise Error('Read data at wrong time')
411        if n:
412            n = n[0]
413            n = min(n, self.dlen)
414        else:
415            n = self.dlen
416        rv = b''
417        while len(rv) < n:
418            rv = rv + self._read(n-len(rv))
419        self.dlen = self.dlen - n
420        return rv
421
422    def close_data(self):
423        if self.state != _DID_HEADER:
424            raise Error('close_data at wrong time')
425        if self.dlen:
426            dummy = self._read(self.dlen)
427        self._checkcrc()
428        self.state = _DID_DATA
429
430    def read_rsrc(self, *n):
431        if self.state == _DID_HEADER:
432            self.close_data()
433        if self.state != _DID_DATA:
434            raise Error('Read resource data at wrong time')
435        if n:
436            n = n[0]
437            n = min(n, self.rlen)
438        else:
439            n = self.rlen
440        self.rlen = self.rlen - n
441        return self._read(n)
442
443    def close(self):
444        if self.state is None:
445            return
446        try:
447            if self.rlen:
448                dummy = self.read_rsrc(self.rlen)
449            self._checkcrc()
450        finally:
451            self.state = None
452            self.ifp.close()
453
454def hexbin(inp, out):
455    """hexbin(infilename, outfilename) - Decode binhexed file"""
456    ifp = HexBin(inp)
457    finfo = ifp.FInfo
458    if not out:
459        out = ifp.FName
460
461    with io.open(out, 'wb') as ofp:
462        # XXXX Do translation on non-mac systems
463        while True:
464            d = ifp.read(128000)
465            if not d: break
466            ofp.write(d)
467    ifp.close_data()
468
469    d = ifp.read_rsrc(128000)
470    if d:
471        ofp = openrsrc(out, 'wb')
472        ofp.write(d)
473        while True:
474            d = ifp.read_rsrc(128000)
475            if not d: break
476            ofp.write(d)
477        ofp.close()
478
479    ifp.close()
480