summaryrefslogtreecommitdiff
path: root/transcode.c
blob: bc1aec495c57e2fe10472e427b9a73e3a95a9f72 (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
/**********************************************************************

  transcode.c -

  $Author$
  created at: Tue Oct 30 16:10:22 JST 2007

  Copyright (C) 2007 Martin Duerst

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

#include "ruby/ruby.h"
#include "ruby/encoding.h"
#define PType (int)
#include "transcode_data.h"
#include <ctype.h>

static VALUE sym_invalid, sym_undef, sym_ignore, sym_replace;
#define INVALID_IGNORE 0x1
#define INVALID_REPLACE 0x2
#define UNDEF_IGNORE 0x10
#define UNDEF_REPLACE 0x20

/*
 *  Dispatch data and logic
 */

static st_table *transcoder_table, *transcoder_lib_table;

#define TRANSCODER_INTERNAL_SEPARATOR '\t'

static char *
transcoder_key(const char *from_e, const char *to_e)
{
    int to_len = strlen(to_e);
    int from_len = strlen(from_e);
    char *const key = xmalloc(to_len + from_len + 2);

    memcpy(key, to_e, to_len);
    memcpy(key + to_len + 1, from_e, from_len + 1);
    key[to_len] = TRANSCODER_INTERNAL_SEPARATOR;
    return key;
}

void
rb_register_transcoder(const rb_transcoder *tr)
{
    st_data_t k, val = 0;
    const char *const from_e = tr->from_encoding;
    const char *const to_e = tr->to_encoding;
    char *const key = transcoder_key(from_e, to_e);

    if (st_lookup(transcoder_table, (st_data_t)key, &val)) {
	xfree(key);
	rb_raise(rb_eArgError, "transcoder from %s to %s has been already registered",
		 from_e, to_e);
    }
    k = (st_data_t)key;
    if (st_delete(transcoder_lib_table, &k, &val)) {
	xfree((char *)k);
    }
    st_insert(transcoder_table, (st_data_t)key, (st_data_t)tr);
}

static void
declare_transcoder(const char *to, const char *from, const char *lib)
{
    const char *const key = transcoder_key(to, from);
    st_data_t k = (st_data_t)key, val;

    if (st_delete(transcoder_lib_table, &k, &val)) {
	xfree((char *)k);
    }
    st_insert(transcoder_lib_table, (st_data_t)key, (st_data_t)lib);
}

#define MAX_TRANSCODER_LIBNAME_LEN 64
static const char transcoder_lib_prefix[] = "enc/trans/";

void
rb_declare_transcoder(const char *enc1, const char *enc2, const char *lib)
{
    if (!lib || strlen(lib) > MAX_TRANSCODER_LIBNAME_LEN) {
	rb_raise(rb_eArgError, "invalid library name - %s",
		 lib ? lib : "(null)");
    }
    declare_transcoder(enc1, enc2, lib);
    declare_transcoder(enc2, enc1, lib);
}

#define encoding_equal(enc1, enc2) (STRCASECMP(enc1, enc2) == 0)

static const rb_transcoder *
transcode_dispatch(const char* from_encoding, const char* to_encoding)
{
    char *const key = transcoder_key(from_encoding, to_encoding);
    st_data_t k, val = 0;

    while (!st_lookup(transcoder_table, (k = (st_data_t)key), &val) &&
	   st_delete(transcoder_lib_table, &k, &val)) {
	const char *const lib = (const char *)val;
	int len = strlen(lib);
	char path[sizeof(transcoder_lib_prefix) + MAX_TRANSCODER_LIBNAME_LEN];

	xfree((char *)k);
	if (len > MAX_TRANSCODER_LIBNAME_LEN) return NULL;
	memcpy(path, transcoder_lib_prefix, sizeof(transcoder_lib_prefix) - 1);
	memcpy(path + sizeof(transcoder_lib_prefix) - 1, lib, len + 1);
	if (!rb_require(path)) return NULL;
    }
    if (!val) {
	if (!st_lookup(transcoder_table, (st_data_t)key, &val)) {
	    /* multistep logic, via UTF-8 */
	    if (!encoding_equal(from_encoding, "UTF-8") &&
		!encoding_equal(to_encoding, "UTF-8") &&
		transcode_dispatch("UTF-8", to_encoding)) {  /* check that we have a second step */
		return transcode_dispatch(from_encoding, "UTF-8"); /* return first step */
	    }
	    return NULL;
	}
    }
    return (rb_transcoder *)val;
}

static const char*
get_replacement_character(rb_encoding *enc)
{
    static rb_encoding *utf16be_encoding, *utf16le_encoding;
    static rb_encoding *utf32be_encoding, *utf32le_encoding;
    if (!utf16be_encoding) {
	utf16be_encoding = rb_enc_find("UTF-16BE");
	utf16le_encoding = rb_enc_find("UTF-16LE");
	utf32be_encoding = rb_enc_find("UTF-32BE");
	utf32le_encoding = rb_enc_find("UTF-32LE");
    }
    if (rb_enc_asciicompat(enc)) {
	return "?";
    }
    else if (utf16be_encoding = enc) {
	return "\x00?";
    }
    else if (utf16le_encoding = enc) {
	return "?\x00";
    }
    else if (utf32be_encoding = enc) {
	return "\x00\x00\x00?";
    }
    else if (utf32le_encoding = enc) {
	return "?\x00\x00\x00";
    }
    else {
	return "?";
    }
}

/*
 *  Transcoding engine logic
 */
static void
transcode_loop(const unsigned char **in_pos, unsigned char **out_pos,
	       const unsigned char *in_stop, unsigned char *out_stop,
	       const rb_transcoder *my_transcoder,
	       rb_transcoding *my_transcoding,
	       const int opt)
{
    const unsigned char *in_p = *in_pos;
    unsigned char *out_p = *out_pos;
    const BYTE_LOOKUP *conv_tree_start = my_transcoder->conv_tree_start;
    const BYTE_LOOKUP *next_table;
    const unsigned char *char_start;
    unsigned int next_offset;
    VALUE next_info;
    unsigned char next_byte;
    int from_utf8 = my_transcoder->from_utf8;
    unsigned char *out_s = out_stop - my_transcoder->max_output + 1;
    rb_encoding *to_encoding = rb_enc_find(my_transcoder->to_encoding);

    while (in_p < in_stop) {
	char_start = in_p;
	next_table = conv_tree_start;
	if (out_p >= out_s) {
	    int len = (out_p - *out_pos);
	    int new_len = (len + my_transcoder->max_output) * 2;
	    *out_pos = (*my_transcoding->flush_func)(my_transcoding, len, new_len);
	    out_p = *out_pos + len;
	    out_s = *out_pos + new_len - my_transcoder->max_output;
	}
	next_byte = (unsigned char)*in_p++;
      follow_byte:
	next_offset = next_table->base[next_byte];
	next_info = (VALUE)next_table->info[next_offset];
      follow_info:
	switch (next_info & 0x1F) {
	  case NOMAP:
	    *out_p++ = next_byte;
	    continue;
	  case 0x00: case 0x04: case 0x08: case 0x0C:
	  case 0x10: case 0x14: case 0x18: case 0x1C:
	    if (in_p >= in_stop) {
		/* todo: deal with the case of backtracking */
		/* todo: deal with incomplete input (streaming) */
		goto invalid;
	    }
	    next_byte = (unsigned char)*in_p++;
	    if (from_utf8) {
		if ((next_byte&0xC0) == 0x80)
		    next_byte -= 0x80;
		else {
		    in_p--; /* may need to add more code later to revert other things */
		    goto invalid;
		}
	    }
	    next_table = (const BYTE_LOOKUP *)next_info;
	    goto follow_byte;
	    /* maybe rewrite the following cases to use fallthrough???? */
	  case ZERObt: /* drop input */
	    continue;
	  case ONEbt:
	    *out_p++ = getBT1(next_info);
	    continue;
	  case TWObt:
	    *out_p++ = getBT1(next_info);
	    *out_p++ = getBT2(next_info);
	    continue;
	  case FOURbt:
	    *out_p++ = getBT0(next_info);
	  case THREEbt: /* fall through */
	    *out_p++ = getBT1(next_info);
	    *out_p++ = getBT2(next_info);
	    *out_p++ = getBT3(next_info);
	    continue;
	  case FUNii:
	    next_info = (VALUE)(*my_transcoder->func_ii)(next_info);
	    goto follow_info;
	  case FUNsi:
	    next_info = (VALUE)(*my_transcoder->func_si)(char_start);
	    goto follow_info;
	    break;
	  case FUNio:
	    out_p += (VALUE)(*my_transcoder->func_io)(next_info, out_p);
	    break;
	  case FUNso:
	    out_p += (VALUE)(*my_transcoder->func_so)(char_start, out_p);
	    break;
	  case INVALID:
	    goto invalid;
	  case UNDEF:
	    goto undef;
	}
	continue;
      invalid:
	/* deal with invalid byte sequence */
	/* todo: add more alternative behaviors */
	if (opt&INVALID_IGNORE) {
	    continue;
	}
	else if (opt&INVALID_REPLACE) {
	    const char *rep = get_replacement_character(to_encoding);
	    do {
		*out_p++ = *rep++;
	    } while (*rep);
	    continue;
	}
	rb_raise(rb_eRuntimeError /*change exception*/, "invalid byte sequence");
	continue;
      undef:
	/* valid character in from encoding
	 * but no related character(s) in to encoding */
	/* todo: add more alternative behaviors */
	if (opt&UNDEF_IGNORE) {
	    continue;
	}
	else if (opt&UNDEF_REPLACE) {
	    const char *rep = get_replacement_character(to_encoding);
	    do {
		*out_p++ = *rep++;
	    } while (*rep);
	    continue;
	}
	rb_raise(rb_eRuntimeError /*@@@change exception*/, "conversion undefined for byte sequence (maybe invalid byte sequence)");
	continue;
    }
    /* cleanup */
    *in_pos  = in_p;
    *out_pos = out_p;
}


/*
 *  String-specific code
 */

static unsigned char *
str_transcoding_resize(rb_transcoding *my_transcoding, int len, int new_len)
{
    VALUE dest_string = my_transcoding->ruby_string_dest;
    rb_str_resize(dest_string, new_len);
    return (unsigned char *)RSTRING_PTR(dest_string);
}

static int
str_transcode(int argc, VALUE *argv, VALUE *self)
{
    VALUE dest;
    VALUE str = *self;
    long blen, slen;
    unsigned char *buf, *bp, *sp;
    const unsigned char *fromp;
    rb_encoding *from_enc, *to_enc;
    const char *from_e, *to_e;
    int from_encidx, to_encidx;
    VALUE from_encval, to_encval;
    const rb_transcoder *my_transcoder;
    rb_transcoding my_transcoding;
    int final_encoding = 0;
    VALUE opt;
    int options = 0;

    opt = rb_check_convert_type(argv[argc-1], T_HASH, "Hash", "to_hash");
    if (!NIL_P(opt)) {
	VALUE v;

	argc--;
	v = rb_hash_aref(opt, sym_invalid);
	if (NIL_P(v)) {
	}
	else if (v==sym_ignore) {
	    options |= INVALID_IGNORE;
	}
	else if (v==sym_replace) {
	    options |= INVALID_REPLACE;
	    v = rb_hash_aref(opt, sym_replace);
	}
	else {
	    rb_raise(rb_eArgError, "unknown value for invalid: setting");
	}
	v = rb_hash_aref(opt, sym_undef);
	if (NIL_P(v)) {
	}
	else if (v==sym_ignore) {
	    options |= UNDEF_IGNORE;
	}
	else if (v==sym_replace) {
	    options |= UNDEF_REPLACE;
	}
	else {
	    rb_raise(rb_eArgError, "unknown value for undef: setting");
	}
    }
    if (argc < 1 || argc > 2) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 1..2)", argc);
    }
    if ((to_encidx = rb_to_encoding_index(to_encval = argv[0])) < 0) {
	to_enc = 0;
	to_encidx = 0;
	to_e = StringValueCStr(to_encval);
    }
    else {
	to_enc = rb_enc_from_index(to_encidx);
	to_e = rb_enc_name(to_enc);
    }
    if (argc==1) {
	from_encidx = rb_enc_get_index(str);
	from_enc = rb_enc_from_index(from_encidx);
	from_e = rb_enc_name(from_enc);
    }
    else if ((from_encidx = rb_to_encoding_index(from_encval = argv[1])) < 0) {
	from_enc = 0;
	from_e = StringValueCStr(from_encval);
    }
    else {
	from_enc = rb_enc_from_index(from_encidx);
	from_e = rb_enc_name(from_enc);
    }

    if (from_enc && from_enc == to_enc) {
	return -1;
    }
    if (from_enc && to_enc && rb_enc_asciicompat(from_enc) && rb_enc_asciicompat(to_enc)) {
	if (ENC_CODERANGE(str) == ENC_CODERANGE_7BIT) {
	    return to_encidx;
	}
    }
    if (encoding_equal(from_e, to_e)) {
	return -1;
    }

    do { /* loop for multistep transcoding */
	/* later, maybe use smaller intermediate strings for very long strings */
	if (!(my_transcoder = transcode_dispatch(from_e, to_e))) {
	    rb_raise(rb_eArgError, "transcoding not supported (from %s to %s)", from_e, to_e);
	}

	my_transcoding.transcoder = my_transcoder;

	if (my_transcoder->preprocessor) {
	    fromp = sp = (unsigned char *)RSTRING_PTR(str);
	    slen = RSTRING_LEN(str);
	    blen = slen + 30; /* len + margin */
	    dest = rb_str_tmp_new(blen);
	    bp = (unsigned char *)RSTRING_PTR(dest);
	    my_transcoding.ruby_string_dest = dest;
	    (*my_transcoder->preprocessor)(&fromp, &bp, (sp+slen), (bp+blen), &my_transcoding);
	    if (fromp != sp+slen) {
		rb_raise(rb_eArgError, "not fully converted, %"PRIdPTRDIFF" bytes left", sp+slen-fromp);
	    }
	    rb_str_set_len(dest, (char *)bp - RSTRING_PTR(dest));
	    str = dest;
	}
	fromp = sp = (unsigned char *)RSTRING_PTR(str);
	slen = RSTRING_LEN(str);
	blen = slen + 30; /* len + margin */
	dest = rb_str_tmp_new(blen);
	bp = (unsigned char *)RSTRING_PTR(dest);
	my_transcoding.ruby_string_dest = dest;
	my_transcoding.flush_func = str_transcoding_resize;

	transcode_loop(&fromp, &bp, (sp+slen), (bp+blen), my_transcoder, &my_transcoding, options);
	if (fromp != sp+slen) {
	    rb_raise(rb_eArgError, "not fully converted, %"PRIdPTRDIFF" bytes left", sp+slen-fromp);
	}
	buf = (unsigned char *)RSTRING_PTR(dest);
	*bp = '\0';
	rb_str_set_len(dest, bp - buf);
	if (my_transcoder->postprocessor) {
	    str = dest;
	    fromp = sp = (unsigned char *)RSTRING_PTR(str);
	    slen = RSTRING_LEN(str);
	    blen = slen + 30; /* len + margin */
	    dest = rb_str_tmp_new(blen);
	    bp = (unsigned char *)RSTRING_PTR(dest);
	    my_transcoding.ruby_string_dest = dest;
	    (*my_transcoder->postprocessor)(&fromp, &bp, (sp+slen), (bp+blen), &my_transcoding);
	    if (fromp != sp+slen) {
		rb_raise(rb_eArgError, "not fully converted, %"PRIdPTRDIFF" bytes left", sp+slen-fromp);
	    }
	    buf = (unsigned char *)RSTRING_PTR(dest);
	    rb_str_set_len(dest, bp - buf);
	}

	if (encoding_equal(my_transcoder->to_encoding, to_e)) {
	    final_encoding = 1;
	}
	else {
	    from_e = my_transcoder->to_encoding;
	    str = dest;
	}
    } while (!final_encoding);
    /* set encoding */
    if (!to_enc) {
	to_encidx = rb_define_dummy_encoding(to_e);
    }
    *self = dest;

    return to_encidx;
}

/*
 *  call-seq:
 *     str.encode!(encoding [, options] )   => str
 *     str.encode!(to_encoding, from_encoding [, options] )   => str
 *
 *  The first form transcodes the contents of <i>str</i> from
 *  str.encoding to +encoding+.
 *  The second form transcodes the contents of <i>str</i> from
 *  from_encoding to to_encoding.
 *  The options Hash gives details for conversion. See String#encode
 *  for details.
 *  Returns the string even if no changes were made.
 */

static VALUE
str_encode_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr = str;
    int encidx = str_transcode(argc, argv, &newstr);
    int cr = 0;

    if (encidx < 0) return str;
    rb_str_shared_replace(str, newstr);
    rb_enc_associate_index(str, encidx);

    /* transcoded string never be broken. */
    if (rb_enc_asciicompat(rb_enc_from_index(encidx))) {
	rb_str_coderange_scan_restartable(RSTRING_PTR(str), RSTRING_END(str), 0, &cr);
    }
    else {
	cr = ENC_CODERANGE_VALID;
    }
    ENC_CODERANGE_SET(str, cr);
    return str;
}

/*
 *  call-seq:
 *     str.encode(encoding [, options] )   => str
 *     str.encode(to_encoding, from_encoding [, options] )   => str
 *
 *  The first form returns a copy of <i>str</i> transcoded
 *  to encoding +encoding+.
 *  The second form returns a copy of <i>str</i> transcoded
 *  from from_encoding to to_encoding.
 *  The options Hash gives details for conversion. Details
 *  to be added.
 */

static VALUE
str_encode(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    return str_encode_bang(argc, argv, str);
}

VALUE
rb_str_transcode(VALUE str, VALUE to)
{
    return str_encode(1, &to, str);
}

void
Init_transcode(void)
{
    transcoder_table = st_init_strcasetable();
    transcoder_lib_table = st_init_strcasetable();

    sym_invalid = ID2SYM(rb_intern("invalid"));
    sym_undef = ID2SYM(rb_intern("undef"));
    sym_ignore = ID2SYM(rb_intern("ignore"));
    sym_replace = ID2SYM(rb_intern("replace"));

    rb_define_method(rb_cString, "encode", str_encode, -1);
    rb_define_method(rb_cString, "encode!", str_encode_bang, -1);
}