summaryrefslogtreecommitdiffstats
path: root/Modules/binascii.c
blob: cd806723d4978f1b898a4bceb73aa652be1394f7 (plain)
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
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
/***********************************************************
Copyright 1991, 1992, 1993, 1994 by Stichting Mathematisch Centrum,
Amsterdam, The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior permission.

STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

/*
** Routines to represent binary data in ASCII and vice-versa
**
** This module currently supports the following encodings:
** uuencode:
**     	each line encodes 45 bytes (except possibly the last)
**	First char encodes (binary) length, rest data
**	each char encodes 6 bits, as follows:
**	binary: 01234567 abcdefgh ijklmnop
**	ascii:  012345 67abcd efghij klmnop
**	ASCII encoding method is "excess-space": 000000 is encoded as ' ', etc.
**	short binary data is zero-extended (so the bits are always in the
**	right place), this does *not* reflect in the length.
** base64:
**      Line breaks are insignificant, but lines are at most 76 chars
**      each char encodes 6 bits, in similar order as uucode/hqx. Encoding
**      is done via a table.
**      Short binary data is filled (in ASCII) with '='.
** hqx:
**	File starts with introductory text, real data starts and ends
**	with colons.
**	Data consists of three similar parts: info, datafork, resourcefork.
**	Each part is protected (at the end) with a 16-bit crc
**	The binary data is run-length encoded, and then ascii-fied:
**	binary: 01234567 abcdefgh ijklmnop
**	ascii:  012345 67abcd efghij klmnop
**	ASCII encoding is table-driven, see the code.
**	Short binary data results in the runt ascii-byte being output with
**	the bits in the right place.
**
** While I was reading dozens of programs that encode or decode the formats
** here (documentation? hihi:-) I have formulated Jansen's Observation:
**
**	Programs that encode binary data in ASCII are written in
**	such a style that they are as unreadable as possible. Devices used
**	include unnecessary global variables, burying important tables
**	in unrelated sourcefiles, putting functions in include files,
**	using seemingly-descriptive variable names for different purposes,
**	calls to empty subroutines and a host of others.
**
** I have attempted to break with this tradition, but I guess that that
** does make the performance sub-optimal. Oh well, too bad...
**
** Jack Jansen, CWI, July 1995.
*/


#include "Python.h"

static PyObject *Error;
static PyObject *Incomplete;

/*
** hqx lookup table, ascii->binary.
*/

#define RUNCHAR 0x90

#define DONE 0x7F
#define SKIP 0x7E
#define FAIL 0x7D

static unsigned char table_a2b_hqx[256] = {
/*       ^@    ^A    ^B    ^C    ^D    ^E    ^F    ^G   */
/* 0*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
/*       \b    \t    \n    ^K    ^L    \r    ^N    ^O   */
/* 1*/	FAIL, FAIL, SKIP, FAIL, FAIL, SKIP, FAIL, FAIL,
/*       ^P    ^Q    ^R    ^S    ^T    ^U    ^V    ^W   */
/* 2*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
/*       ^X    ^Y    ^Z    ^[    ^\    ^]    ^^    ^_   */
/* 3*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
/*              !     "     #     $     %     &     '   */
/* 4*/	FAIL, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
/*        (     )     *     +     ,     -     .     /   */
/* 5*/	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, FAIL, FAIL,
/*        0     1     2     3     4     5     6     7   */
/* 6*/	0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, FAIL,
/*        8     9     :     ;     <     =     >     ?   */
/* 7*/	0x14, 0x15, DONE, FAIL, FAIL, FAIL, FAIL, FAIL,
/*        @     A     B     C     D     E     F     G   */
/* 8*/	0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,
/*        H     I     J     K     L     M     N     O   */
/* 9*/	0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, FAIL,
/*        P     Q     R     S     T     U     V     W   */
/*10*/	0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, FAIL,
/*        X     Y     Z     [     \     ]     ^     _   */
/*11*/	0x2C, 0x2D, 0x2E, 0x2F, FAIL, FAIL, FAIL, FAIL,
/*        `     a     b     c     d     e     f     g   */
/*12*/	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, FAIL,
/*        h     i     j     k     l     m     n     o   */
/*13*/	0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, FAIL, FAIL,
/*        p     q     r     s     t     u     v     w   */
/*14*/	0x3D, 0x3E, 0x3F, FAIL, FAIL, FAIL, FAIL, FAIL,
/*        x     y     z     {     |     }     ~    ^?   */
/*15*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
/*16*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,
};

static unsigned char table_b2a_hqx[] =
    "!\"#$%&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ[`abcdefhijklmpqr";

static char table_a2b_base64[] = {
	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
	52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-1,-1, /* Note PAD->0 */
	-1, 0, 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,-1, -1,-1,-1,-1,
	-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
	41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};

#define BASE64_PAD '='
#define BASE64_MAXBIN 57	/* Max binary chunk size (76 char line) */

static unsigned char table_b2a_base64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";



static unsigned short crctab_hqx[256] = {
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
    0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
    0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
    0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
    0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
    0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
    0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
    0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
    0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
    0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
    0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
    0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
    0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
    0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
    0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
    0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
    0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
};

static char doc_a2b_uu[] = "(ascii) -> bin. Decode a line of uuencoded data";

static PyObject *
binascii_a2b_uu(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	PyObject *rv;
	int ascii_len, bin_len;
	
	if ( !PyArg_ParseTuple(args, "s#", &ascii_data, &ascii_len) )
		return NULL;

	/* First byte: binary data length (in bytes) */
	bin_len = (*ascii_data++ - ' ') & 077;
	ascii_len--;

	/* Allocate the buffer */
	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )
		return NULL;
	bin_data = (unsigned char *)PyString_AsString(rv);
	
	for( ; bin_len > 0 ; ascii_len--, ascii_data++ ) {
		this_ch = *ascii_data;
		if ( this_ch == '\n' || this_ch == '\r' || ascii_len <= 0) {
			/*
			** Whitespace. Assume some spaces got eaten at
			** end-of-line. (We check this later)
			*/
			this_ch = 0;
	        } else {
			/* Check the character for legality */
			if ( this_ch < ' ' || this_ch > (' ' + 63)) {
				PyErr_SetString(Error, "Illegal char");
				Py_DECREF(rv);
				return NULL;
			}
			this_ch = (this_ch - ' ') & 077;
		}
		/*
		** Shift it in on the low end, and see if there's
		** a byte ready for output.
		*/
		leftchar = (leftchar << 6) | (this_ch);
		leftbits += 6;
		if ( leftbits >= 8 ) {
			leftbits -= 8;
			*bin_data++ = (leftchar >> leftbits) & 0xff;
			leftchar &= ((1 << leftbits) - 1);
			bin_len--;
		}
	}
	/*
	** Finally, check that if there's anything left on the line
	** that it's whitespace only.
	*/
	while( ascii_len-- > 0 ) {
		this_ch = *ascii_data++;
		if ( this_ch != ' ' && this_ch != '\n' && this_ch != '\r' ) {
			PyErr_SetString(Error, "Trailing garbage");
			Py_DECREF(rv);
			return NULL;
		}
	}
	return rv;
}

static char doc_b2a_uu[] = "(bin) -> ascii. Uuencode line of data";
	
static PyObject *
binascii_b2a_uu(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	PyObject *rv;
	int bin_len;
	
	if ( !PyArg_ParseTuple(args, "s#", &bin_data, &bin_len) )
		return NULL;
	if ( bin_len > 45 ) {
		/* The 45 is a limit that appears in all uuencode's */
		PyErr_SetString(Error, "At most 45 bytes at once");
		return NULL;
	}

	/* We're lazy and allocate to much (fixed up later) */
	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2)) == NULL )
		return NULL;
	ascii_data = (unsigned char *)PyString_AsString(rv);

	/* Store the length */
	*ascii_data++ = ' ' + (bin_len & 077);
	
	for( ; bin_len > 0 || leftbits != 0 ; bin_len--, bin_data++ ) {
		/* Shift the data (or padding) into our buffer */
		if ( bin_len > 0 )	/* Data */
			leftchar = (leftchar << 8) | *bin_data;
		else			/* Padding */
			leftchar <<= 8;
		leftbits += 8;

		/* See if there are 6-bit groups ready */
		while ( leftbits >= 6 ) {
			this_ch = (leftchar >> (leftbits-6)) & 0x3f;
			leftbits -= 6;
			*ascii_data++ = this_ch + ' ';
		}
	}
	*ascii_data++ = '\n';	/* Append a courtesy newline */
	
	_PyString_Resize(&rv, (ascii_data - (unsigned char *)PyString_AsString(rv)));
	return rv;
}

static char doc_a2b_base64[] = "(ascii) -> bin. Decode a line of base64 data";

static PyObject *
binascii_a2b_base64(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	int npad = 0;
	PyObject *rv;
	int ascii_len, bin_len;
	
	if ( !PyArg_ParseTuple(args, "s#", &ascii_data, &ascii_len) )
		return NULL;

	bin_len = ((ascii_len+3)/4)*3; /* Upper bound, corrected later */

	/* Allocate the buffer */
	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )
		return NULL;
	bin_data = (unsigned char *)PyString_AsString(rv);
	bin_len = 0;
	for( ; ascii_len > 0 ; ascii_len--, ascii_data++ ) {
		/*
		** XXXX I don't do any checks on the chars, ignoring
		** any illegal chars. Hope this is correct...
		*/
		this_ch = (*ascii_data & 0x7f);
		if ( this_ch == BASE64_PAD )
			npad++;
		this_ch = table_a2b_base64[(*ascii_data) & 0x7f];
		if ( this_ch == -1 ) continue;
		/*
		** Shift it in on the low end, and see if there's
		** a byte ready for output.
		*/
		leftchar = (leftchar << 6) | (this_ch);
		leftbits += 6;
		if ( leftbits >= 8 ) {
			leftbits -= 8;
			*bin_data++ = (leftchar >> leftbits) & 0xff;
			leftchar &= ((1 << leftbits) - 1);
			bin_len++;
		}
	}
	/* Check that no bits are left */
	if ( leftbits ) {
		PyErr_SetString(Error, "Incorrect padding");
		Py_DECREF(rv);
		return NULL;
	}
	/* and remove any padding */
	bin_len -= npad;
	/* and set string size correctly */
	_PyString_Resize(&rv, bin_len);
	return rv;
}

static char doc_b2a_base64[] = "(bin) -> ascii. Base64-code line of data";
	
static PyObject *
binascii_b2a_base64(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	PyObject *rv;
	int bin_len;
	
	if ( !PyArg_ParseTuple(args, "s#", &bin_data, &bin_len) )
		return NULL;
	if ( bin_len > BASE64_MAXBIN ) {
		PyErr_SetString(Error, "Too much data for base64 line");
		return NULL;
	}
	
	/* We're lazy and allocate to much (fixed up later) */
	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2)) == NULL )
		return NULL;
	ascii_data = (unsigned char *)PyString_AsString(rv);

	for( ; bin_len > 0 ; bin_len--, bin_data++ ) {
		/* Shift the data into our buffer */
		leftchar = (leftchar << 8) | *bin_data;
		leftbits += 8;

		/* See if there are 6-bit groups ready */
		while ( leftbits >= 6 ) {
			this_ch = (leftchar >> (leftbits-6)) & 0x3f;
			leftbits -= 6;
			*ascii_data++ = table_b2a_base64[this_ch];
		}
	}
	if ( leftbits == 2 ) {
		*ascii_data++ = table_b2a_base64[(leftchar&3) << 4];
		*ascii_data++ = BASE64_PAD;
		*ascii_data++ = BASE64_PAD;
	} else if ( leftbits == 4 ) {
		*ascii_data++ = table_b2a_base64[(leftchar&0xf) << 2];
		*ascii_data++ = BASE64_PAD;
	} 
	*ascii_data++ = '\n';	/* Append a courtesy newline */
	
	_PyString_Resize(&rv, (ascii_data - (unsigned char *)PyString_AsString(rv)));
	return rv;
}

static char doc_a2b_hqx[] = "ascii -> bin, done. Decode .hqx coding";

static PyObject *
binascii_a2b_hqx(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	PyObject *rv;
	int len;
	int done = 0;
	
	if ( !PyArg_ParseTuple(args, "s#", &ascii_data, &len) )
		return NULL;

	/* Allocate a string that is too big (fixed later) */
	if ( (rv=PyString_FromStringAndSize(NULL, len)) == NULL )
		return NULL;
	bin_data = (unsigned char *)PyString_AsString(rv);

	for( ; len > 0 ; len--, ascii_data++ ) {
		/* Get the byte and look it up */
		this_ch = table_a2b_hqx[*ascii_data];
		if ( this_ch == SKIP )
			continue;
		if ( this_ch == FAIL ) {
			PyErr_SetString(Error, "Illegal char");
			Py_DECREF(rv);
			return NULL;
		}
		if ( this_ch == DONE ) {
			/* The terminating colon */
			done = 1;
			break;
		}

		/* Shift it into the buffer and see if any bytes are ready */
		leftchar = (leftchar << 6) | (this_ch);
		leftbits += 6;
		if ( leftbits >= 8 ) {
			leftbits -= 8;
			*bin_data++ = (leftchar >> leftbits) & 0xff;
			leftchar &= ((1 << leftbits) - 1);
		}
	}
	
	if ( leftbits && !done ) {
		PyErr_SetString(Incomplete,
				"String has incomplete number of bytes");
		Py_DECREF(rv);
		return NULL;
	}
	_PyString_Resize(&rv, (bin_data - (unsigned char *)PyString_AsString(rv)));
	if ( rv )
		return Py_BuildValue("Oi", rv, done);
	return NULL;
}

static char doc_rlecode_hqx[] = "Binhex RLE-code binary data";

static PyObject *
binascii_rlecode_hqx(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *in_data, *out_data;
	PyObject *rv;
	unsigned char ch;
	int in, inend, len;
	
	if ( !PyArg_ParseTuple(args, "s#", &in_data, &len) )
		return NULL;

	/* Worst case: output is twice as big as input (fixed later) */
	if ( (rv=PyString_FromStringAndSize(NULL, len*2)) == NULL )
		return NULL;
	out_data = (unsigned char *)PyString_AsString(rv);
	
	for( in=0; in<len; in++) {
		ch = in_data[in];
		if ( ch == RUNCHAR ) {
			/* RUNCHAR. Escape it. */
			*out_data++ = RUNCHAR;
			*out_data++ = 0;
		} else {
			/* Check how many following are the same */
			for(inend=in+1;
			    inend<len && in_data[inend] == ch &&
			        inend < in+255;
			    inend++) ;
			if ( inend - in > 3 ) {
				/* More than 3 in a row. Output RLE. */
				*out_data++ = ch;
				*out_data++ = RUNCHAR;
				*out_data++ = inend-in;
				in = inend-1;
			} else {
				/* Less than 3. Output the byte itself */
				*out_data++ = ch;
			}
		}
	}
	_PyString_Resize(&rv, (out_data - (unsigned char *)PyString_AsString(rv)));
	return rv;
}

static char doc_b2a_hqx[] = "Encode .hqx data";
	
static PyObject *
binascii_b2a_hqx(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *ascii_data, *bin_data;
	int leftbits = 0;
	unsigned char this_ch;
	unsigned int leftchar = 0;
	PyObject *rv;
	int len;
	
	if ( !PyArg_ParseTuple(args, "s#", &bin_data, &len) )
		return NULL;

	/* Allocate a buffer that is at least large enough */
	if ( (rv=PyString_FromStringAndSize(NULL, len*2)) == NULL )
		return NULL;
	ascii_data = (unsigned char *)PyString_AsString(rv);
	
	for( ; len > 0 ; len--, bin_data++ ) {
		/* Shift into our buffer, and output any 6bits ready */
		leftchar = (leftchar << 8) | *bin_data;
		leftbits += 8;
		while ( leftbits >= 6 ) {
			this_ch = (leftchar >> (leftbits-6)) & 0x3f;
			leftbits -= 6;
			*ascii_data++ = table_b2a_hqx[this_ch];
		}
	}
	/* Output a possible runt byte */
	if ( leftbits ) {
		leftchar <<= (6-leftbits);
		*ascii_data++ = table_b2a_hqx[leftchar & 0x3f];
	}
	_PyString_Resize(&rv, (ascii_data - (unsigned char *)PyString_AsString(rv)));
	return rv;
}

static char doc_rledecode_hqx[] = "Decode hexbin RLE-coded string";
	
static PyObject *
binascii_rledecode_hqx(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *in_data, *out_data;
	unsigned char in_byte, in_repeat;
	PyObject *rv;
	int in_len, out_len, out_len_left;

	if ( !PyArg_ParseTuple(args, "s#", &in_data, &in_len) )
		return NULL;

	/* Empty string is a special case */
	if ( in_len == 0 )
		return Py_BuildValue("s", "");

	/* Allocate a buffer of reasonable size. Resized when needed */
	out_len = in_len*2;
	if ( (rv=PyString_FromStringAndSize(NULL, out_len)) == NULL )
		return NULL;
	out_len_left = out_len;
	out_data = (unsigned char *)PyString_AsString(rv);

	/*
	** We need two macros here to get/put bytes and handle
	** end-of-buffer for input and output strings.
	*/
#define INBYTE(b) \
    do { \
	if ( --in_len < 0 ) { \
		PyErr_SetString(Incomplete, ""); \
	        Py_DECREF(rv); \
		return NULL; \
	} \
	b = *in_data++; \
    } while(0)
	    
#define OUTBYTE(b) \
    do { \
	if ( --out_len_left < 0 ) { \
		_PyString_Resize(&rv, 2*out_len); \
		if ( rv == NULL ) return NULL; \
		out_data = (unsigned char *)PyString_AsString(rv) + out_len; \
		out_len_left = out_len; \
		out_len = out_len * 2; \
	} \
	*out_data++ = b; \
    } while(0)

	/*
	** Handle first byte separately (since we have to get angry
	** in case of an orphaned RLE code).
	*/
	INBYTE(in_byte);

	if (in_byte == RUNCHAR) {
		INBYTE(in_repeat);
		if (in_repeat != 0) {
			/* Note Error, not Incomplete (which is at the end
			** of the string only). This is a programmer error.
			*/
			PyErr_SetString(Error, "Orphaned RLE code at start");
			Py_DECREF(rv);
			return NULL;
		}
		OUTBYTE(RUNCHAR);
	} else {
		OUTBYTE(in_byte);
	}
	
	while( in_len > 0 ) {
		INBYTE(in_byte);

		if (in_byte == RUNCHAR) {
			INBYTE(in_repeat);
			if ( in_repeat == 0 ) {
				/* Just an escaped RUNCHAR value */
				OUTBYTE(RUNCHAR);
			} else {
				/* Pick up value and output a sequence of it */
				in_byte = out_data[-1];
				while ( --in_repeat > 0 )
					OUTBYTE(in_byte);
			}
		} else {
			/* Normal byte */
			OUTBYTE(in_byte);
		}
	}
	_PyString_Resize(&rv, (out_data - (unsigned char *)PyString_AsString(rv)));
	return rv;
}

static char doc_crc_hqx[] = "(data, oldcrc) -> newcrc. Compute hqx CRC incrementally";

static PyObject *
binascii_crc_hqx(self, args)
	PyObject *self;
	PyObject *args;
{
	unsigned char *bin_data;
	unsigned int crc;
	int len;
	
	if ( !PyArg_ParseTuple(args, "s#i", &bin_data, &len, &crc) )
		return NULL;

	while(len--) {
		crc=((crc<<8)&0xff00)^crctab_hqx[((crc>>8)&0xff)^*bin_data++];
	}

	return Py_BuildValue("i", crc);
}

/* List of functions defined in the module */

static struct PyMethodDef binascii_module_methods[] = {
	{"a2b_uu",		binascii_a2b_uu,	1,	doc_a2b_uu},
	{"b2a_uu",		binascii_b2a_uu,	1,	doc_b2a_uu},
	{"a2b_base64",		binascii_a2b_base64,	1,
		 doc_a2b_base64},
	{"b2a_base64",		binascii_b2a_base64,	1,
		 doc_b2a_base64},
	{"a2b_hqx",		binascii_a2b_hqx,	1,	doc_a2b_hqx},
	{"b2a_hqx",		binascii_b2a_hqx,	1,	doc_b2a_hqx},
	{"rlecode_hqx",		binascii_rlecode_hqx,	1,
		 doc_rlecode_hqx},
	{"rledecode_hqx",	binascii_rledecode_hqx,	1,
		 doc_rledecode_hqx},
	{"crc_hqx",		binascii_crc_hqx,	1,	doc_crc_hqx},
	{NULL,			NULL}		/* sentinel */
};


/* Initialization function for the module (*must* be called initbinascii) */
static char doc_binascii[] = "Conversion between binary data and ASCII";

void
initbinascii()
{
	PyObject *m, *d, *x;

	/* Create the module and add the functions */
	m = Py_InitModule("binascii", binascii_module_methods);

	d = PyModule_GetDict(m);
	x = PyString_FromString(doc_binascii);
	PyDict_SetItemString(d, "__doc__", x);

	Error = PyString_FromString("binascii.Error");
	PyDict_SetItemString(d, "Error", Error);
	Incomplete = PyString_FromString("binascii.Incomplete");
	PyDict_SetItemString(d, "Incomplete", Incomplete);

	/* Check for errors */
	if (PyErr_Occurred())
		Py_FatalError("can't initialize module binascii");
}