summaryrefslogtreecommitdiff
path: root/support/word2x/strip.cc
blob: 5ab4b6794ff8ae9b220723652473c0aa575a5918 (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
/* $Id: junk_filter.cc,v 1.40 1998/06/14 06:25:36 dps Exp $ */

/* This code filters out almost all the "junk" in word documents and
 * is useful for extracting the text from word documents. I think this
 * program produces better signal to noise that catdoc. */

#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
#include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif /* HAVE_STRINGS_H */
#ifdef HAVE_CTYPE_H
#include <ctype.h>
#endif /* HAVE_CTYPE_H */
#include <stream.h>
#include <iostream.h>
#include <fstream.h>
#include "strip.h"
#include "tune.h"

/* Note: This is a two stage filter that outputs 0 or 1 characters
   per input character and thus can use the same buffer safely. */

/* Read more */
int word_junk_filter::__fill(const char *b, int n, int sp, int offset)
{
    int end, nr;

    if (n>0)
	memmove(buf+offset, b, n);
    offset+=n+sp;
    if (offset>JUNK_FILT_BUFSIZE)
    {
	cerr<<"junk_filter::__fill: start offset "<<offset<<" >buffer size"
	    "(fatal)\n";
	exit(1);
    }
    if (offset<JUNK_FILT_BUFSIZE)
    {
	is->read(buf+offset, JUNK_FILT_BUFSIZE-offset);
	nr=is->gcount();
    }
    else
	nr=0;
    pos+=nr;
    end=nr+n;
    return end;
}


/* Junk filtering. Buffer size must be >=RESUME_CHARS */
int word_junk_filter::filter_junk(const char *b, int ns)
{
    int i, d, n, top_run;

    if ((n=__fill(b, ns, junk_end_usage, 1))==0)
	return 0;
    if (junk_end_usage>0)
	memcpy(buf+ns+1, junk_end_buf, junk_end_usage);
    if (init==INIT_SKIPPED)
    {
	init=INIT_DONE;		// Finished init
	ns=0;			// Process all the data
	text_size=0;		// Text size is zero
    }

#ifdef DEBUG_FILTER_FILL
    printf("\n---refill ns=%d junk_end_usage=%d\n", ns, junk_end_usage);
    printf("---end=%d mode=%d\n", n, mode);
#endif

    /* Correctness of this loop depends on d<=i at the top of the
       loop. The claims * by inductioon about the fake variable __adj__ suffice
       to prove this. All the relevant commments are prefixed by CS */

    top_run=0;
    /*** CS: __adj__=1 ****/
    for (i=ns+1, d=ns; i<=n; i++)	// Ignore already processed data pushed back
    {
	/*** CS: i==d+junk_end_usage+__adj__ and __adj__>=0 here by induction ***/
	/*** CS: if mode==SKIP_JUNK or SKIP_JUNK_WASPRN then __adj__>=1       ***/
#ifdef DEBUG_FILTER
	printf("mode %d, char[%i] (t=%d) %c, asc=%d\n", mode, i, n,
	       buf[i], junk_end_usage);
#endif
	switch(mode)
	{
	case NORMAL:
	    /* Normal mode. OK becasue change in d at most 1 and junk_end_usage=0 */
	    if (buf[i]==0)
	    {
		junk_end_usage=0;
		junk_size=0;
		mode=SKIP_JUNK;
		break;
	    }
	    if (buf[i] & 0x80)
	    {
		/*** CS: by induction junk_end_usage==top_run ***/
		junk_end_buf[junk_end_usage++]=buf[i];	// Save character
		top_run++;				// Increment top run counter
		/*** CS: __adj__++ ***/
		if (top_run==tune.max_top_run)
		{
		    junk_size=top_run;			// Top bit characters are junk
		    junk_end_usage=0;			// Throw away characters
		    mode=SKIP_JUNK;			// End junk skipping mode
		    /*** CS: __adj__ += top_run ***/
		    break;
		}
		break;					// Exit switch
	    }
	    /* Top bit not set */
	    if (top_run)
	    {
		memcpy(buf+d, junk_end_buf, junk_end_usage); // OK by ind hyp.
		d+=junk_end_usage;
		junk_end_usage=0;			// Ind. hyp now true
		top_run=0;				// Reset top_run counter.
	    }
	    /* Add character */
	    buf[d++]=buf[i];
	    text_size++;
	    if (unicode!=__UNI_NO)
		mode=UNICODE_Z;
	    break;
	 
	case UNICODE_Z:
	    /* unicode zero mode. OK because change in d is 0 and junk_end_usage=0 */
	    if (buf[i]==0)
	    {
		mode=NORMAL; // 0 => Back to printable character mode
		/*** CS: __adj__++ ***/
	    }
	    else
	    {
#ifdef UNICODE_MARKERS
		printf("\n*** Mode %d: %d Got %d expected 0\n", mode,
		       UNICODE_Z, buf[i]);
#endif
		junk_end_usage=0;
		junk_size=0;
		mode=SKIP_JUNK;
		/*** CS: __adj__++ ***/
	    }
	    break;

	case SKIP_JUNK_WASPRN:
	    /* Skip junk was printable, added for unicode documents */
	    /* OK because junk_end_usage chages by at most 1 and d stays fixed */
	    if ((++junk_size)==tune.max_junk && text_size>tune.min_text)
	    {
#ifdef DEBUG_SINK_START
		cerr<<"Enter sink mode\n";
#endif /* DEBUG_SINK_START */
		/*** CS: __adj__++ ***/
		mode=SINK_JUNK;	// Sink junk
		break;
	    }
	    if  (tune.options.unicode_aggresive)
	    {
		/* Agresive unicode mode: insist on the MSBs appearing */
		if (unicode!=__UNI_NO)
		{
		    if (buf[i]!=0)
		    {
			/*** CS: __adj__+=junk_end_usage ***/
			junk_end_usage=0;
		    }
		    mode=SKIP_JUNK;
		    /*** CS: __adj__++ ***/
		    break;
		}
	    }
	    else
	    {
		/* Non-aggersive unicode mode: simply skip the MSB */
		if (buf[i]==0 && unicode!=__UNI_NO)
		{
		    /*** CS: __adj__++ ***/
		    break;	// Accept zeros
		}
	    }
	    /* Fall thru */
	    
	case SKIP_JUNK:
	    /* Junk skipping mode */
	    if ((++junk_size)==tune.max_junk && text_size>tune.min_text)
	    {
#ifdef DEBUG_SINK_START
		cerr<<"Enter sink mode\n";
#endif /* DEBUG_SINK_START */
		mode=SINK_JUNK;	// Sink junk
		/*** CS: __adj__++ ***/
		break;
	    }
	    if (isprint(buf[i]) || buf[i]=='\r' || buf[i]=='\n'
		|| buf[i]=='\t')
	    {
#ifdef DEBUG_RESTART
		printf("---Accepted *%c*, usage=%d\n", buf[i], junk_end_usage);
#endif
		junk_end_buf[junk_end_usage++]=buf[i]; // Save character
		if (unicode!=__UNI_NO)
		    mode=SKIP_JUNK_WASPRN; // For unicode documents
	    }
	    else
	    {
		/* Reset junk buffer usage counter */
		/*** CS: __adj__+=junk_end_usage+1 ***/
#ifdef DEBUG_RESTART
		if (junk_end_usage!=0)
		printf("---Rejected %d, usage=%d\n", buf[i], junk_end_usage);
#endif
		junk_end_usage=0;
		break;
	    }
	    if (junk_end_usage<tune.resume_chars)
		break;
	    /* Turn nomral mode back on */
#ifdef DEBUG_RESTART
	    printf("---back normal mode count=%d\n", junk_size);
#endif
	    /* The __adj__ analysis is *vital* here; if __Adj__=0 then d>i occurs */
	    /* however forutnately this is impossible by the claims that __adj__  */
	    /* and indcution proves.                                              */

	    /**** CS: __adj__>=1 here by indcution. Thus i>=d+junk_end_usage+1 ****/
	    mode=(unicode==__UNI_NO) ? NORMAL : UNICODE_Z;
	    buf[d]=0x7f;				// Mark suspect position
	    memcpy(buf+d+1, junk_end_buf, junk_end_usage); // Nothing clobbered by [1]
	    d+=junk_end_usage+1;			// Advance d
	    junk_end_usage=0;				// Clear junk end buffer
	    /*** CS: __adj__-- ***/
	    break;

	case SINK_JUNK:
	    /*** CS: __adj__++ ***/
	    break;

	default:
	    cerr<<"word_junk_filter::filter_junk: Invalid mode "<<mode
		<<" (fatal)\n";
	    exit(1);
	}
    }
    return d;
}

int word_junk_filter::underflow(void)
{
    int s,d,last;
    int end;

    do				// While no characters
    {
	/* Fill the buffer */
	if (init==INIT_NONE)
	{
	    if (is!=NULL)
	    {
		init=INIT_SKIPPED;
		ns=this->skip_to_start();
		end=this->filter_junk(buf, ns);
	    }
	    else
		return EOF;	// If no input stream return EOF
	}
	else
	{
	    end=this->filter_junk(&save, ns);
	    ns=0;
	}
	
	/* Check for EOF */
	if (end==0 && is->eof())
	    return EOF;
	
	ns=0;
	/* Collapse multi-character sequeneces */
	for (s=0, d=0, last=-1; s<end; s++)
	{
	    switch(buf[s])
	    {
	    case '\n':
		if (last=='\r')
		    continue;	// \n \r to \r
		break;
		
		
	    case '\r':
		if (last=='\n')
		    d--;	// \r \n to \r
		break;
		
		
	    case 0x07:
		if (last=='\r')
		    d--;	// \n <TAB SEP> to <TAB SEP>
		break;
		
	    default:
		break;
	    }
	    last=buf[d]=buf[s];
	    d++;
	}
	
	if (end!=1 && (buf[d-1]=='\r' || buf[d-1]=='\n'))
	{
	    d--;
	    ns=1;
	    save=buf[d];
	}
    } while (d==0);
    setg(buf, buf, buf+d);
    return(buf[0] & 0xff);
}


/* Skip to start */
int word_junk_filter::skip_to_start(void)
{
    int zc,ffc,c,n,i,rej,limit=-1;
    char back[2*ST_ASC_VCHARS_UNICODE+ST_REJ_LIMIT+4];
    int bp;
    long pos=0;

    enum { FIND_BEGIN, SKIP_ONE, FIND_ASC, FIND_ASC_WASASC, DONE } mode;
    zc=0; ffc=0; i=0; n=0; bp=0; rej=-1;
    mode=FIND_BEGIN;
    while (mode!=DONE)
    {
	/* If need a refill */
	if (i==n)
	{
	    /* Fill buffer */
	    n=this->__fill(back,bp,0,1);
	    if (n==0)
		return 0;
	    pos+=n-bp;
#ifdef DEBUG_SKIP_FILL
	    printf("---skip--- refill bp=%x, pos=%x\n", bp, pos);
#endif
	    /* Ignore first saved character */
	    if (mode==FIND_ASC)
		mode=SKIP_ONE;
	    i=0;
	    bp=0;
	}

#ifdef DEBUG_SKIP
	printf("char %c mode %d, c=%d, pos=%x, i=%d l=%d, rej=%d\n", buf[i+1],
		   mode, c, pos++, i, limit, rej);
#endif
	switch(mode)
	{
	case FIND_BEGIN:
	    switch(buf[i+1])
	    {
	    case 0:
		zc++;
		ffc=0;
		break;

	    case ((char) 0xff):
		ffc++;
		zc=0;
		break;

	    default:
		if (zc>=tune.st_min_zeros ||
		    (ffc>=tune.st_min_ff && tune.options.ff_intro))
		{
		    unicode=__UNI_PROBE;
		    back[bp++]=buf[i+1];
		    c=0;
		    rej=0;
		    mode=FIND_ASC_WASASC; // Ignore this character deliberately
		}
		else
		{
		    zc=0;
		    ffc=0;
		}
		break;
	    }
	    break;

	case SKIP_ONE:
	    back[bp++]=buf[i+1];
	    c=0;
	    rej=0;
	    mode=FIND_ASC_WASASC;
	    break;

	case FIND_ASC_WASASC:	// unicode support
	    if (buf[i+1]==0 && unicode!=__UNI_NO)
	    {
		if (unicode==__UNI_PROBE)
		{
		    limit=tune.unicode_st; // Start characters needed
		    /* FIXME: Anyone got a better method of doing this? */
		    if ((pos+i) % 2==0)
		    {
			unicode=__UNI_YES_BE; // 0 is first (even) bu#yte
		    }
		    else
		    {
			unicode=__UNI_YES_LE; // 0 is second (odd) byte
		    }
		    back[bp++]=buf[i+1];
		    mode=FIND_ASC;	      // Inist next character not zero
#ifdef DEBUG_SKIP_UNI
		    cerr<<"Characters are unicode "
			<<((unicode==__UNI_YES_LE) ? "litle" : "big")
			<<" endian\n";
#endif
		}
		else
		    back[bp++]=buf[i+1];
		c++;
		break;
	    }
	    else if (unicode==__UNI_PROBE)
	    {
#ifdef DEBUG_SKIP_UNI
		if (unicode==__UNI_PROBE)
		    cerr<<"Characters are not unicode\n";
#endif
		limit=tune.non_unicode_st; // Start characters needed
		unicode=__UNI_NO;	   // Non unicode
		mode=FIND_ASC;		   // Finding printable mode
	    }
	    /* fall thru */

	case FIND_ASC:
	    if (isprint(buf[i+1]) || buf[i+1]=='\r' || buf[i+1]=='\n'
		|| buf[i+1]=='\t')	      // If is printable
	    {
		back[bp++]=buf[i+1];	      // Store character
		c++;			      // Increase count
		if (unicode!=__UNI_NO)
		    mode=FIND_ASC_WASASC;     // Unicode hack...
	    }
	    else
	    {
		back[bp++]=buf[i+1];	      // Store caharcetr
		if (buf[i+1]!=0)
		    rej++;		      // Adjust reject count
		if (buf[i+1]==0 || rej>tune.st_rej_limit) // 0 or reject limit
		{
		    bp=0;		      // Reset buffer pointer
		    unicode=__UNI_PROBE;      // Set unicode status to unknonw
		    ffc=(buf[i+1]== (char) 0xff) ? 1 : 0; // reset ff count
		    zc=(buf[i+1]==0) ? 1 : 0; // reset zeros count
		    mode=FIND_BEGIN ;	      // Find leading characters mode
		}
	    }
	    if (limit==-1)		      // Bug catcher
	    {
		cerr<<"Bug: limit still -1 at point #1\n";
		exit(2);
	    }
	    if (c==limit)		      // IF found enough
	    {
#ifdef DEBUG_SKIP
		printf("***** Enter exit phase ****\n");
#endif
		mode=DONE;		      // Finished skipping
	    }
	    break;

	case DONE:
	    cerr<<"skip_to_start: loop called in done mode\n";
	    break;

	default:
	    cerr<<"skip_to_start: Mode invalid\n";
	    break;
	}
	i++;
    }
#ifdef DEBUG_SKIP_MOVE
    printf("%c%c%c\n", buf[i-bp+1], buf[i-bp+2], buf[i-bp+3]);
#endif
    memmove(buf, buf+i-bp+1, n-i+bp);	      // Move memory
    return(n-i+bp);			      // Return count
}


/* Option handling stuff for tuning this module. Note that only long options
 * are supported. If you lack long options these features are not avialable. */
/* set default tuning */
void word_junk_filter::set_dfl_tuning(void)
{
#ifdef AGGRESIVE_UNICODE
    tune.options.unicode_aggresive=AGGRESIVE_UNICODE; // Aggresive unicode mode
#else
    tune.options.unicode_aggresive=1;		      // Aggresive unicode mode
#endif /* AGGRESIVE_UNICODE */
    tune.resume_chars=RESUME_CHARS;		      // Resume characters
    tune.st_min_zeros=ST_MIN_ZEROS;		      // Minimum zeros
    tune.st_rej_limit=ST_REJ_LIMIT;		      // Reject chars tolerance
    tune.st_min_ff=ST_MIN_FF;			      // Minimum ff's (alternative to 0s)
    tune.options.ff_intro=ALLOW_FF_LEADIN;	      // Enable leading ff's
    tune.non_unicode_st=ST_ASC_VCHARS;		      // ok characters leadin
    tune.unicode_st=ST_ASC_VCHARS_UNICODE;	      // ok unicode characters
    tune.min_text=SINK_MIN_TEXT;		      // text required before sink mode
    tune.max_junk=SINK_JUNK_CNT;		      // junk required for sink mode
    tune.max_top_run=MAX_TOP_RUN;		      // Max run length of top bits set
}

int word_junk_filter::do_reset(void)
{
	pos=0;
	init=INIT_NONE;
	mode=NORMAL;
	junk_end_usage=0;
	ns=0;
	return 1;		// Success
}