1/*	$NetBSD: gen_decode.c,v 1.1.1.1 2011/04/13 18:14:40 elric Exp $	*/
2
3/*
4 * Copyright (c) 1997 - 2006 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include "gen_locl.h"
37#include "lex.h"
38
39__RCSID("$NetBSD: gen_decode.c,v 1.1.1.1 2011/04/13 18:14:40 elric Exp $");
40
41static void
42decode_primitive (const char *typename, const char *name, const char *forwstr)
43{
44#if 0
45    fprintf (codefile,
46	     "e = decode_%s(p, len, %s, &l);\n"
47	     "%s;\n",
48	     typename,
49	     name,
50	     forwstr);
51#else
52    fprintf (codefile,
53	     "e = der_get_%s(p, len, %s, &l);\n"
54	     "if(e) %s;\np += l; len -= l; ret += l;\n",
55	     typename,
56	     name,
57	     forwstr);
58#endif
59}
60
61static void
62find_tag (const Type *t,
63	  Der_class *cl, Der_type *ty, unsigned *tag)
64{
65    switch (t->type) {
66    case TBitString:
67	*cl  = ASN1_C_UNIV;
68	*ty  = PRIM;
69	*tag = UT_BitString;
70	break;
71    case TBoolean:
72	*cl  = ASN1_C_UNIV;
73	*ty  = PRIM;
74	*tag = UT_Boolean;
75	break;
76    case TChoice:
77	errx(1, "Cannot have recursive CHOICE");
78    case TEnumerated:
79	*cl  = ASN1_C_UNIV;
80	*ty  = PRIM;
81	*tag = UT_Enumerated;
82	break;
83    case TGeneralString:
84	*cl  = ASN1_C_UNIV;
85	*ty  = PRIM;
86	*tag = UT_GeneralString;
87	break;
88    case TTeletexString:
89	*cl  = ASN1_C_UNIV;
90	*ty  = PRIM;
91	*tag = UT_TeletexString;
92	break;
93    case TGeneralizedTime:
94	*cl  = ASN1_C_UNIV;
95	*ty  = PRIM;
96	*tag = UT_GeneralizedTime;
97	break;
98    case TIA5String:
99	*cl  = ASN1_C_UNIV;
100	*ty  = PRIM;
101	*tag = UT_IA5String;
102	break;
103    case TInteger:
104	*cl  = ASN1_C_UNIV;
105	*ty  = PRIM;
106	*tag = UT_Integer;
107	break;
108    case TNull:
109	*cl  = ASN1_C_UNIV;
110	*ty  = PRIM;
111	*tag = UT_Null;
112	break;
113    case TOID:
114	*cl  = ASN1_C_UNIV;
115	*ty  = PRIM;
116	*tag = UT_OID;
117	break;
118    case TOctetString:
119	*cl  = ASN1_C_UNIV;
120	*ty  = PRIM;
121	*tag = UT_OctetString;
122	break;
123    case TPrintableString:
124	*cl  = ASN1_C_UNIV;
125	*ty  = PRIM;
126	*tag = UT_PrintableString;
127	break;
128    case TSequence:
129    case TSequenceOf:
130	*cl  = ASN1_C_UNIV;
131	*ty  = CONS;
132	*tag = UT_Sequence;
133	break;
134    case TSet:
135    case TSetOf:
136	*cl  = ASN1_C_UNIV;
137	*ty  = CONS;
138	*tag = UT_Set;
139	break;
140    case TTag:
141	*cl  = t->tag.tagclass;
142	*ty  = is_primitive_type(t->subtype->type) ? PRIM : CONS;
143	*tag = t->tag.tagvalue;
144	break;
145    case TType:
146	if ((t->symbol->stype == Stype && t->symbol->type == NULL)
147	    || t->symbol->stype == SUndefined) {
148	    lex_error_message("%s is imported or still undefined, "
149			      " can't generate tag checking data in CHOICE "
150			      "without this information",
151			      t->symbol->name);
152	    exit(1);
153	}
154	find_tag(t->symbol->type, cl, ty, tag);
155	return;
156    case TUTCTime:
157	*cl  = ASN1_C_UNIV;
158	*ty  = PRIM;
159	*tag = UT_UTCTime;
160	break;
161    case TUTF8String:
162	*cl  = ASN1_C_UNIV;
163	*ty  = PRIM;
164	*tag = UT_UTF8String;
165	break;
166    case TBMPString:
167	*cl  = ASN1_C_UNIV;
168	*ty  = PRIM;
169	*tag = UT_BMPString;
170	break;
171    case TUniversalString:
172	*cl  = ASN1_C_UNIV;
173	*ty  = PRIM;
174	*tag = UT_UniversalString;
175	break;
176    case TVisibleString:
177	*cl  = ASN1_C_UNIV;
178	*ty  = PRIM;
179	*tag = UT_VisibleString;
180	break;
181    default:
182	abort();
183    }
184}
185
186static void
187range_check(const char *name,
188	    const char *length,
189	    const char *forwstr,
190	    struct range *r)
191{
192    if (r->min == r->max + 2 || r->min < r->max)
193	fprintf (codefile,
194		 "if ((%s)->%s > %d) {\n"
195		 "e = ASN1_MAX_CONSTRAINT; %s;\n"
196		 "}\n",
197		 name, length, r->max, forwstr);
198    if (r->min - 1 == r->max || r->min < r->max)
199	fprintf (codefile,
200		 "if ((%s)->%s < %d) {\n"
201		 "e = ASN1_MIN_CONSTRAINT; %s;\n"
202		 "}\n",
203		 name, length, r->min, forwstr);
204    if (r->max == r->min)
205	fprintf (codefile,
206		 "if ((%s)->%s != %d) {\n"
207		 "e = ASN1_EXACT_CONSTRAINT; %s;\n"
208		 "}\n",
209		 name, length, r->min, forwstr);
210}
211
212static int
213decode_type (const char *name, const Type *t, int optional,
214	     const char *forwstr, const char *tmpstr, const char *dertype)
215{
216    switch (t->type) {
217    case TType: {
218	if (optional)
219	    fprintf(codefile,
220		    "%s = calloc(1, sizeof(*%s));\n"
221		    "if (%s == NULL) %s;\n",
222		    name, name, name, forwstr);
223	fprintf (codefile,
224		 "e = decode_%s(p, len, %s, &l);\n",
225		 t->symbol->gen_name, name);
226	if (optional) {
227	    fprintf (codefile,
228		     "if(e) {\n"
229		     "free(%s);\n"
230		     "%s = NULL;\n"
231		     "} else {\n"
232		     "p += l; len -= l; ret += l;\n"
233		     "}\n",
234		     name, name);
235	} else {
236	    fprintf (codefile,
237		     "if(e) %s;\n",
238		     forwstr);
239	    fprintf (codefile,
240		     "p += l; len -= l; ret += l;\n");
241	}
242	break;
243    }
244    case TInteger:
245	if(t->members) {
246	    fprintf(codefile,
247		    "{\n"
248		    "int enumint;\n");
249	    decode_primitive ("integer", "&enumint", forwstr);
250	    fprintf(codefile,
251		    "*%s = enumint;\n"
252		    "}\n",
253		    name);
254	} else if (t->range == NULL) {
255	    decode_primitive ("heim_integer", name, forwstr);
256	} else if (t->range->min == INT_MIN && t->range->max == INT_MAX) {
257	    decode_primitive ("integer", name, forwstr);
258	} else if (t->range->min == 0 && t->range->max == UINT_MAX) {
259	    decode_primitive ("unsigned", name, forwstr);
260	} else if (t->range->min == 0 && t->range->max == INT_MAX) {
261	    decode_primitive ("unsigned", name, forwstr);
262	} else
263	    errx(1, "%s: unsupported range %d -> %d",
264		 name, t->range->min, t->range->max);
265	break;
266    case TBoolean:
267      decode_primitive ("boolean", name, forwstr);
268      break;
269    case TEnumerated:
270	decode_primitive ("enumerated", name, forwstr);
271	break;
272    case TOctetString:
273	if (dertype) {
274	    fprintf(codefile,
275		    "if (%s == CONS) {\n",
276		    dertype);
277	    decode_primitive("octet_string_ber", name, forwstr);
278	    fprintf(codefile,
279		    "} else {\n");
280	}
281	decode_primitive ("octet_string", name, forwstr);
282	if (dertype)
283	    fprintf(codefile, "}\n");
284	if (t->range)
285	    range_check(name, "length", forwstr, t->range);
286	break;
287    case TBitString: {
288	Member *m;
289	int pos = 0;
290
291	if (ASN1_TAILQ_EMPTY(t->members)) {
292	    decode_primitive ("bit_string", name, forwstr);
293	    break;
294	}
295	fprintf(codefile,
296		"if (len < 1) return ASN1_OVERRUN;\n"
297		"p++; len--; ret++;\n");
298	fprintf(codefile,
299		"do {\n"
300		"if (len < 1) break;\n");
301	ASN1_TAILQ_FOREACH(m, t->members, members) {
302	    while (m->val / 8 > pos / 8) {
303		fprintf (codefile,
304			 "p++; len--; ret++;\n"
305			 "if (len < 1) break;\n");
306		pos += 8;
307	    }
308	    fprintf (codefile,
309		     "(%s)->%s = (*p >> %d) & 1;\n",
310		     name, m->gen_name, 7 - m->val % 8);
311	}
312	fprintf(codefile,
313		"} while(0);\n");
314	fprintf (codefile,
315		 "p += len; ret += len;\n");
316	break;
317    }
318    case TSequence: {
319	Member *m;
320
321	if (t->members == NULL)
322	    break;
323
324	ASN1_TAILQ_FOREACH(m, t->members, members) {
325	    char *s = NULL;
326
327	    if (m->ellipsis)
328		continue;
329
330	    if (asprintf (&s, "%s(%s)->%s", m->optional ? "" : "&",
331			  name, m->gen_name) < 0 || s == NULL)
332		errx(1, "malloc");
333	    decode_type (s, m->type, m->optional, forwstr, m->gen_name, NULL);
334	    free (s);
335	}
336
337	break;
338    }
339    case TSet: {
340	Member *m;
341	unsigned int memno;
342
343	if(t->members == NULL)
344	    break;
345
346	fprintf(codefile, "{\n");
347	fprintf(codefile, "unsigned int members = 0;\n");
348	fprintf(codefile, "while(len > 0) {\n");
349	fprintf(codefile,
350		"Der_class class;\n"
351		"Der_type type;\n"
352		"int tag;\n"
353		"e = der_get_tag (p, len, &class, &type, &tag, NULL);\n"
354		"if(e) %s;\n", forwstr);
355	fprintf(codefile, "switch (MAKE_TAG(class, type, tag)) {\n");
356	memno = 0;
357	ASN1_TAILQ_FOREACH(m, t->members, members) {
358	    char *s;
359
360	    assert(m->type->type == TTag);
361
362	    fprintf(codefile, "case MAKE_TAG(%s, %s, %s):\n",
363		    classname(m->type->tag.tagclass),
364		    is_primitive_type(m->type->subtype->type) ? "PRIM" : "CONS",
365		    valuename(m->type->tag.tagclass, m->type->tag.tagvalue));
366
367	    if (asprintf (&s, "%s(%s)->%s", m->optional ? "" : "&", name, m->gen_name) < 0 || s == NULL)
368		errx(1, "malloc");
369	    if(m->optional)
370		fprintf(codefile,
371			"%s = calloc(1, sizeof(*%s));\n"
372			"if (%s == NULL) { e = ENOMEM; %s; }\n",
373			s, s, s, forwstr);
374	    decode_type (s, m->type, 0, forwstr, m->gen_name, NULL);
375	    free (s);
376
377	    fprintf(codefile, "members |= (1 << %d);\n", memno);
378	    memno++;
379	    fprintf(codefile, "break;\n");
380	}
381	fprintf(codefile,
382		"default:\n"
383		"return ASN1_MISPLACED_FIELD;\n"
384		"break;\n");
385	fprintf(codefile, "}\n");
386	fprintf(codefile, "}\n");
387	memno = 0;
388	ASN1_TAILQ_FOREACH(m, t->members, members) {
389	    char *s;
390
391	    if (asprintf (&s, "%s->%s", name, m->gen_name) < 0 || s == NULL)
392		errx(1, "malloc");
393	    fprintf(codefile, "if((members & (1 << %d)) == 0)\n", memno);
394	    if(m->optional)
395		fprintf(codefile, "%s = NULL;\n", s);
396	    else if(m->defval)
397		gen_assign_defval(s, m->defval);
398	    else
399		fprintf(codefile, "return ASN1_MISSING_FIELD;\n");
400	    free(s);
401	    memno++;
402	}
403	fprintf(codefile, "}\n");
404	break;
405    }
406    case TSetOf:
407    case TSequenceOf: {
408	char *n = NULL;
409	char *sname = NULL;
410
411	fprintf (codefile,
412		 "{\n"
413		 "size_t %s_origlen = len;\n"
414		 "size_t %s_oldret = ret;\n"
415		 "size_t %s_olen = 0;\n"
416		 "void *%s_tmp;\n"
417		 "ret = 0;\n"
418		 "(%s)->len = 0;\n"
419		 "(%s)->val = NULL;\n",
420		 tmpstr,
421		 tmpstr,
422		 tmpstr,
423		 tmpstr,
424		 name,
425		 name);
426
427	fprintf (codefile,
428		 "while(ret < %s_origlen) {\n"
429		 "size_t %s_nlen = %s_olen + sizeof(*((%s)->val));\n"
430		 "if (%s_olen > %s_nlen) { e = ASN1_OVERFLOW; %s; }\n"
431		 "%s_olen = %s_nlen;\n"
432		 "%s_tmp = realloc((%s)->val, %s_olen);\n"
433		 "if (%s_tmp == NULL) { e = ENOMEM; %s; }\n"
434		 "(%s)->val = %s_tmp;\n",
435		 tmpstr,
436		 tmpstr, tmpstr, name,
437		 tmpstr, tmpstr, forwstr,
438		 tmpstr, tmpstr,
439		 tmpstr, name, tmpstr,
440		 tmpstr, forwstr,
441		 name, tmpstr);
442
443	if (asprintf (&n, "&(%s)->val[(%s)->len]", name, name) < 0 || n == NULL)
444	    errx(1, "malloc");
445	if (asprintf (&sname, "%s_s_of", tmpstr) < 0 || sname == NULL)
446	    errx(1, "malloc");
447	decode_type (n, t->subtype, 0, forwstr, sname, NULL);
448	fprintf (codefile,
449		 "(%s)->len++;\n"
450		 "len = %s_origlen - ret;\n"
451		 "}\n"
452		 "ret += %s_oldret;\n"
453		 "}\n",
454		 name,
455		 tmpstr, tmpstr);
456	if (t->range)
457	    range_check(name, "len", forwstr, t->range);
458	free (n);
459	free (sname);
460	break;
461    }
462    case TGeneralizedTime:
463	decode_primitive ("generalized_time", name, forwstr);
464	break;
465    case TGeneralString:
466	decode_primitive ("general_string", name, forwstr);
467	break;
468    case TTeletexString:
469	decode_primitive ("general_string", name, forwstr);
470	break;
471    case TTag:{
472    	char *tname = NULL, *typestring = NULL;
473	char *ide = NULL;
474
475	if (asprintf(&typestring, "%s_type", tmpstr) < 0 || typestring == NULL)
476	    errx(1, "malloc");
477
478	fprintf(codefile,
479		"{\n"
480		"size_t %s_datalen, %s_oldlen;\n"
481		"Der_type %s;\n",
482		tmpstr, tmpstr, typestring);
483	if(support_ber)
484	    fprintf(codefile,
485		    "int is_indefinite;\n");
486
487	fprintf(codefile, "e = der_match_tag_and_length(p, len, %s, &%s, %s, "
488		"&%s_datalen, &l);\n",
489		classname(t->tag.tagclass),
490		typestring,
491		valuename(t->tag.tagclass, t->tag.tagvalue),
492		tmpstr);
493
494	/* XXX hardcode for now */
495	if (support_ber && t->subtype->type == TOctetString) {
496	    ide = typestring;
497	} else {
498	    fprintf(codefile,
499		    "if (e == 0 && %s != %s) { e = ASN1_BAD_ID; }\n",
500		    typestring,
501		    is_primitive_type(t->subtype->type) ? "PRIM" : "CONS");
502	}
503
504	if(optional) {
505	    fprintf(codefile,
506		    "if(e) {\n"
507		    "%s = NULL;\n"
508		    "} else {\n"
509		     "%s = calloc(1, sizeof(*%s));\n"
510		     "if (%s == NULL) { e = ENOMEM; %s; }\n",
511		     name, name, name, name, forwstr);
512	} else {
513	    fprintf(codefile, "if(e) %s;\n", forwstr);
514	}
515	fprintf (codefile,
516		 "p += l; len -= l; ret += l;\n"
517		 "%s_oldlen = len;\n",
518		 tmpstr);
519	if(support_ber)
520	    fprintf (codefile,
521		     "if((is_indefinite = _heim_fix_dce(%s_datalen, &len)) < 0)\n"
522		     "{ e = ASN1_BAD_FORMAT; %s; }\n"
523		     "if (is_indefinite) { if (len < 2) { e = ASN1_OVERRUN; %s; } len -= 2; }",
524		     tmpstr, forwstr, forwstr);
525	else
526	    fprintf(codefile,
527		    "if (%s_datalen > len) { e = ASN1_OVERRUN; %s; }\n"
528		    "len = %s_datalen;\n", tmpstr, forwstr, tmpstr);
529	if (asprintf (&tname, "%s_Tag", tmpstr) < 0 || tname == NULL)
530	    errx(1, "malloc");
531	decode_type (name, t->subtype, 0, forwstr, tname, ide);
532	if(support_ber)
533	    fprintf(codefile,
534		    "if(is_indefinite){\n"
535		    "len += 2;\n"
536		    "e = der_match_tag_and_length(p, len, "
537		    "(Der_class)0, &%s, UT_EndOfContent, "
538		    "&%s_datalen, &l);\n"
539		    "if(e) %s;\n"
540		    "p += l; len -= l; ret += l;\n"
541		    "if (%s != (Der_type)0) { e = ASN1_BAD_ID; %s; }\n"
542		    "} else \n",
543		    typestring,
544		    tmpstr,
545		    forwstr,
546		    typestring, forwstr);
547	fprintf(codefile,
548		"len = %s_oldlen - %s_datalen;\n",
549		tmpstr, tmpstr);
550	if(optional)
551	    fprintf(codefile,
552		    "}\n");
553	fprintf(codefile,
554		"}\n");
555	free(tname);
556	free(typestring);
557	break;
558    }
559    case TChoice: {
560	Member *m, *have_ellipsis = NULL;
561	const char *els = "";
562
563	if (t->members == NULL)
564	    break;
565
566	ASN1_TAILQ_FOREACH(m, t->members, members) {
567	    const Type *tt = m->type;
568	    char *s = NULL;
569	    Der_class cl;
570	    Der_type  ty;
571	    unsigned  tag;
572
573	    if (m->ellipsis) {
574		have_ellipsis = m;
575		continue;
576	    }
577
578	    find_tag(tt, &cl, &ty, &tag);
579
580	    fprintf(codefile,
581		    "%sif (der_match_tag(p, len, %s, %s, %s, NULL) == 0) {\n",
582		    els,
583		    classname(cl),
584		    ty ? "CONS" : "PRIM",
585		    valuename(cl, tag));
586	    if (asprintf (&s, "%s(%s)->u.%s", m->optional ? "" : "&",
587			  name, m->gen_name) < 0 || s == NULL)
588		errx(1, "malloc");
589	    decode_type (s, m->type, m->optional, forwstr, m->gen_name, NULL);
590	    fprintf(codefile,
591		    "(%s)->element = %s;\n",
592		    name, m->label);
593	    free(s);
594	    fprintf(codefile,
595		    "}\n");
596	    els = "else ";
597	}
598	if (have_ellipsis) {
599	    fprintf(codefile,
600		    "else {\n"
601		    "(%s)->u.%s.data = calloc(1, len);\n"
602		    "if ((%s)->u.%s.data == NULL) {\n"
603		    "e = ENOMEM; %s;\n"
604		    "}\n"
605		    "(%s)->u.%s.length = len;\n"
606		    "memcpy((%s)->u.%s.data, p, len);\n"
607		    "(%s)->element = %s;\n"
608		    "p += len;\n"
609		    "ret += len;\n"
610		    "len -= len;\n"
611		    "}\n",
612		    name, have_ellipsis->gen_name,
613		    name, have_ellipsis->gen_name,
614		    forwstr,
615		    name, have_ellipsis->gen_name,
616		    name, have_ellipsis->gen_name,
617		    name, have_ellipsis->label);
618	} else {
619	    fprintf(codefile,
620		    "else {\n"
621		    "e = ASN1_PARSE_ERROR;\n"
622		    "%s;\n"
623		    "}\n",
624		    forwstr);
625	}
626	break;
627    }
628    case TUTCTime:
629	decode_primitive ("utctime", name, forwstr);
630	break;
631    case TUTF8String:
632	decode_primitive ("utf8string", name, forwstr);
633	break;
634    case TPrintableString:
635	decode_primitive ("printable_string", name, forwstr);
636	break;
637    case TIA5String:
638	decode_primitive ("ia5_string", name, forwstr);
639	break;
640    case TBMPString:
641	decode_primitive ("bmp_string", name, forwstr);
642	break;
643    case TUniversalString:
644	decode_primitive ("universal_string", name, forwstr);
645	break;
646    case TVisibleString:
647	decode_primitive ("visible_string", name, forwstr);
648	break;
649    case TNull:
650	fprintf (codefile, "/* NULL */\n");
651	break;
652    case TOID:
653	decode_primitive ("oid", name, forwstr);
654	break;
655    default :
656	abort ();
657    }
658    return 0;
659}
660
661void
662generate_type_decode (const Symbol *s)
663{
664    int preserve = preserve_type(s->name) ? TRUE : FALSE;
665
666    fprintf (codefile, "int ASN1CALL\n"
667	     "decode_%s(const unsigned char *p,"
668	     " size_t len, %s *data, size_t *size)\n"
669	     "{\n",
670	     s->gen_name, s->gen_name);
671
672    switch (s->type->type) {
673    case TInteger:
674    case TBoolean:
675    case TOctetString:
676    case TOID:
677    case TGeneralizedTime:
678    case TGeneralString:
679    case TTeletexString:
680    case TUTF8String:
681    case TPrintableString:
682    case TIA5String:
683    case TBMPString:
684    case TUniversalString:
685    case TVisibleString:
686    case TUTCTime:
687    case TNull:
688    case TEnumerated:
689    case TBitString:
690    case TSequence:
691    case TSequenceOf:
692    case TSet:
693    case TSetOf:
694    case TTag:
695    case TType:
696    case TChoice:
697	fprintf (codefile,
698		 "size_t ret = 0;\n"
699		 "size_t l;\n"
700		 "int e;\n");
701	if (preserve)
702	    fprintf (codefile, "const unsigned char *begin = p;\n");
703
704	fprintf (codefile, "\n");
705	fprintf (codefile, "memset(data, 0, sizeof(*data));\n"); /* hack to avoid `unused variable' */
706
707	decode_type ("data", s->type, 0, "goto fail", "Top", NULL);
708	if (preserve)
709	    fprintf (codefile,
710		     "data->_save.data = calloc(1, ret);\n"
711		     "if (data->_save.data == NULL) { \n"
712		     "e = ENOMEM; goto fail; \n"
713		     "}\n"
714		     "data->_save.length = ret;\n"
715		     "memcpy(data->_save.data, begin, ret);\n");
716	fprintf (codefile,
717		 "if(size) *size = ret;\n"
718		 "return 0;\n");
719	fprintf (codefile,
720		 "fail:\n"
721		 "free_%s(data);\n"
722		 "return e;\n",
723		 s->gen_name);
724	break;
725    default:
726	abort ();
727    }
728    fprintf (codefile, "}\n\n");
729}
730