xref: /netbsd-src/external/bsd/file/dist/src/funcs.c (revision e7ac2a8b5bd66fa2e050809de09a075c36a7014d)
1 /*	$NetBSD: funcs.c,v 1.18 2020/06/15 00:37:24 christos Exp $	*/
2 
3 /*
4  * Copyright (c) Christos Zoulas 2003.
5  * All Rights Reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice immediately at the beginning of the file, without modification,
12  *    this list of conditions, and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
21  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 #include "file.h"
30 
31 #ifndef	lint
32 #if 0
33 FILE_RCSID("@(#)$File: funcs.c,v 1.115 2020/02/20 15:50:20 christos Exp $")
34 #else
35 __RCSID("$NetBSD: funcs.c,v 1.18 2020/06/15 00:37:24 christos Exp $");
36 #endif
37 #endif	/* lint */
38 
39 #include "magic.h"
40 #include <assert.h>
41 #include <stdarg.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <ctype.h>
45 #if defined(HAVE_WCHAR_H)
46 #include <wchar.h>
47 #endif
48 #if defined(HAVE_WCTYPE_H)
49 #include <wctype.h>
50 #endif
51 #include <limits.h>
52 
53 #ifndef SIZE_MAX
54 #define SIZE_MAX	((size_t)~0)
55 #endif
56 
57 protected char *
58 file_copystr(char *buf, size_t blen, size_t width, const char *str)
59 {
60 	if (++width > blen)
61 		width = blen;
62 	strlcpy(buf, str, width);
63 	return buf;
64 }
65 
66 private void
67 file_clearbuf(struct magic_set *ms)
68 {
69 	free(ms->o.buf);
70 	ms->o.buf = NULL;
71 	ms->o.blen = 0;
72 }
73 
74 private int
75 file_checkfield(char *msg, size_t mlen, const char *what, const char **pp)
76 {
77 	const char *p = *pp;
78 	int fw = 0;
79 
80 	while (*p && isdigit((unsigned char)*p))
81 		fw = fw * 10 + (*p++ - '0');
82 
83 	*pp = p;
84 
85 	if (fw < 1024)
86 		return 1;
87 	if (msg)
88 		snprintf(msg, mlen, "field %s too large: %d", what, fw);
89 
90 	return 0;
91 }
92 
93 protected int
94 file_checkfmt(char *msg, size_t mlen, const char *fmt)
95 {
96 	for (const char *p = fmt; *p; p++) {
97 		if (*p != '%')
98 			continue;
99 		if (*++p == '%')
100 			continue;
101 		// Skip uninteresting.
102 		while (strchr("0.'+- ", *p) != NULL)
103 			p++;
104 		if (*p == '*') {
105 			if (msg)
106 				snprintf(msg, mlen, "* not allowed in format");
107 			return -1;
108 		}
109 
110 		if (!file_checkfield(msg, mlen, "width", &p))
111 			return -1;
112 
113 		if (*p == '.') {
114 			p++;
115 			if (!file_checkfield(msg, mlen, "precision", &p))
116 				return -1;
117 		}
118 
119 		if (!isalpha((unsigned char)*p)) {
120 			if (msg)
121 				snprintf(msg, mlen, "bad format char: %c", *p);
122 			return -1;
123 		}
124 	}
125 	return 0;
126 }
127 
128 /*
129  * Like printf, only we append to a buffer.
130  */
131 protected int
132 file_vprintf(struct magic_set *ms, const char *fmt, va_list ap)
133 {
134 	int len;
135 	char *buf, *newstr;
136 	char tbuf[1024];
137 
138 	if (ms->event_flags & EVENT_HAD_ERR)
139 		return 0;
140 
141 	if (file_checkfmt(tbuf, sizeof(tbuf), fmt)) {
142 		file_clearbuf(ms);
143 		file_error(ms, 0, "Bad magic format `%s' (%s)", fmt, tbuf);
144 		return -1;
145 	}
146 
147 	len = vasprintf(&buf, fmt, ap);
148 	if (len < 0 || (size_t)len > 1024 || len + ms->o.blen > 1024 * 1024) {
149 		size_t blen = ms->o.blen;
150 		free(buf);
151 		file_clearbuf(ms);
152 		file_error(ms, 0, "Output buffer space exceeded %d+%zu", len,
153 		    blen);
154 		return -1;
155 	}
156 
157 	if (ms->o.buf != NULL) {
158 		len = asprintf(&newstr, "%s%s", ms->o.buf, buf);
159 		free(buf);
160 		if (len < 0)
161 			goto out;
162 		free(ms->o.buf);
163 		buf = newstr;
164 	}
165 	ms->o.buf = buf;
166 	ms->o.blen = len;
167 	return 0;
168 out:
169 	file_clearbuf(ms);
170 	file_error(ms, errno, "vasprintf failed");
171 	return -1;
172 }
173 
174 protected int
175 file_printf(struct magic_set *ms, const char *fmt, ...)
176 {
177 	int rv;
178 	va_list ap;
179 
180 	va_start(ap, fmt);
181 	rv = file_vprintf(ms, fmt, ap);
182 	va_end(ap);
183 	return rv;
184 }
185 
186 /*
187  * error - print best error message possible
188  */
189 /*VARARGS*/
190 __attribute__((__format__(__printf__, 3, 0)))
191 private void
192 file_error_core(struct magic_set *ms, int error, const char *f, va_list va,
193     size_t lineno)
194 {
195 	/* Only the first error is ok */
196 	if (ms->event_flags & EVENT_HAD_ERR)
197 		return;
198 	if (lineno != 0) {
199 		file_clearbuf(ms);
200 		(void)file_printf(ms, "line %" SIZE_T_FORMAT "u:", lineno);
201 	}
202 	if (ms->o.buf && *ms->o.buf)
203 		(void)file_printf(ms, " ");
204 	(void)file_vprintf(ms, f, va);
205 	if (error > 0)
206 		(void)file_printf(ms, " (%s)", strerror(error));
207 	ms->event_flags |= EVENT_HAD_ERR;
208 	ms->error = error;
209 }
210 
211 /*VARARGS*/
212 protected void
213 file_error(struct magic_set *ms, int error, const char *f, ...)
214 {
215 	va_list va;
216 	va_start(va, f);
217 	file_error_core(ms, error, f, va, 0);
218 	va_end(va);
219 }
220 
221 /*
222  * Print an error with magic line number.
223  */
224 /*VARARGS*/
225 protected void
226 file_magerror(struct magic_set *ms, const char *f, ...)
227 {
228 	va_list va;
229 	va_start(va, f);
230 	file_error_core(ms, 0, f, va, ms->line);
231 	va_end(va);
232 }
233 
234 protected void
235 file_oomem(struct magic_set *ms, size_t len)
236 {
237 	file_error(ms, errno, "cannot allocate %" SIZE_T_FORMAT "u bytes",
238 	    len);
239 }
240 
241 protected void
242 file_badseek(struct magic_set *ms)
243 {
244 	file_error(ms, errno, "error seeking");
245 }
246 
247 protected void
248 file_badread(struct magic_set *ms)
249 {
250 	file_error(ms, errno, "error reading");
251 }
252 
253 #ifndef COMPILE_ONLY
254 
255 protected int
256 file_separator(struct magic_set *ms)
257 {
258 	return file_printf(ms, "\n- ");
259 }
260 
261 static int
262 checkdone(struct magic_set *ms, int *rv)
263 {
264 	if ((ms->flags & MAGIC_CONTINUE) == 0)
265 		return 1;
266 	if (file_separator(ms) == -1)
267 		*rv = -1;
268 	return 0;
269 }
270 
271 protected int
272 file_default(struct magic_set *ms, size_t nb)
273 {
274 	if (ms->flags & MAGIC_MIME) {
275 		if ((ms->flags & MAGIC_MIME_TYPE) &&
276 		    file_printf(ms, "application/%s",
277 			nb ? "octet-stream" : "x-empty") == -1)
278 			return -1;
279 		return 1;
280 	}
281 	if (ms->flags & MAGIC_APPLE) {
282 		if (file_printf(ms, "UNKNUNKN") == -1)
283 			return -1;
284 		return 1;
285 	}
286 	if (ms->flags & MAGIC_EXTENSION) {
287 		if (file_printf(ms, "???") == -1)
288 			return -1;
289 		return 1;
290 	}
291 	return 0;
292 }
293 
294 /*
295  * The magic detection functions return:
296  *	 1: found
297  *	 0: not found
298  *	-1: error
299  */
300 /*ARGSUSED*/
301 protected int
302 file_buffer(struct magic_set *ms, int fd, struct stat *st,
303     const char *inname __attribute__ ((__unused__)),
304     const void *buf, size_t nb)
305 {
306 	int m = 0, rv = 0, looks_text = 0;
307 	const char *code = NULL;
308 	const char *code_mime = "binary";
309 	const char *def = "data";
310 	const char *ftype = NULL;
311 	char *rbuf = NULL;
312 	struct buffer b;
313 
314 	buffer_init(&b, fd, st, buf, nb);
315 	ms->mode = b.st.st_mode;
316 
317 	if (nb == 0) {
318 		def = "empty";
319 		goto simple;
320 	} else if (nb == 1) {
321 		def = "very short file (no magic)";
322 		goto simple;
323 	}
324 
325 	if ((ms->flags & MAGIC_NO_CHECK_ENCODING) == 0) {
326 		looks_text = file_encoding(ms, &b, NULL, 0,
327 		    &code, &code_mime, &ftype);
328 	}
329 
330 #ifdef __EMX__
331 	if ((ms->flags & MAGIC_NO_CHECK_APPTYPE) == 0 && inname) {
332 		m = file_os2_apptype(ms, inname, &b);
333 		if ((ms->flags & MAGIC_DEBUG) != 0)
334 			(void)fprintf(stderr, "[try os2_apptype %d]\n", m);
335 		switch (m) {
336 		case -1:
337 			return -1;
338 		case 0:
339 			break;
340 		default:
341 			return 1;
342 		}
343 	}
344 #endif
345 #if HAVE_FORK
346 	/* try compression stuff */
347 	if ((ms->flags & MAGIC_NO_CHECK_COMPRESS) == 0) {
348 		m = file_zmagic(ms, &b, inname);
349 		if ((ms->flags & MAGIC_DEBUG) != 0)
350 			(void)fprintf(stderr, "[try zmagic %d]\n", m);
351 		if (m) {
352 			goto done_encoding;
353 		}
354 	}
355 #endif
356 	/* Check if we have a tar file */
357 	if ((ms->flags & MAGIC_NO_CHECK_TAR) == 0) {
358 		m = file_is_tar(ms, &b);
359 		if ((ms->flags & MAGIC_DEBUG) != 0)
360 			(void)fprintf(stderr, "[try tar %d]\n", m);
361 		if (m) {
362 			if (checkdone(ms, &rv))
363 				goto done;
364 		}
365 	}
366 
367 	/* Check if we have a JSON file */
368 	if ((ms->flags & MAGIC_NO_CHECK_JSON) == 0) {
369 		m = file_is_json(ms, &b);
370 		if ((ms->flags & MAGIC_DEBUG) != 0)
371 			(void)fprintf(stderr, "[try json %d]\n", m);
372 		if (m) {
373 			if (checkdone(ms, &rv))
374 				goto done;
375 		}
376 	}
377 
378 	/* Check if we have a CSV file */
379 	if ((ms->flags & MAGIC_NO_CHECK_CSV) == 0) {
380 		m = file_is_csv(ms, &b, looks_text);
381 		if ((ms->flags & MAGIC_DEBUG) != 0)
382 			(void)fprintf(stderr, "[try csv %d]\n", m);
383 		if (m) {
384 			if (checkdone(ms, &rv))
385 				goto done;
386 		}
387 	}
388 
389 	/* Check if we have a CDF file */
390 	if ((ms->flags & MAGIC_NO_CHECK_CDF) == 0) {
391 		m = file_trycdf(ms, &b);
392 		if ((ms->flags & MAGIC_DEBUG) != 0)
393 			(void)fprintf(stderr, "[try cdf %d]\n", m);
394 		if (m) {
395 			if (checkdone(ms, &rv))
396 				goto done;
397 		}
398 	}
399 #ifdef BUILTIN_ELF
400 	if ((ms->flags & MAGIC_NO_CHECK_ELF) == 0 && nb > 5 && fd != -1) {
401 		file_pushbuf_t *pb;
402 		/*
403 		 * We matched something in the file, so this
404 		 * *might* be an ELF file, and the file is at
405 		 * least 5 bytes long, so if it's an ELF file
406 		 * it has at least one byte past the ELF magic
407 		 * number - try extracting information from the
408 		 * ELF headers that cannot easily be  extracted
409 		 * with rules in the magic file. We we don't
410 		 * print the information yet.
411 		 */
412 		if ((pb = file_push_buffer(ms)) == NULL)
413 			return -1;
414 
415 		rv = file_tryelf(ms, &b);
416 		rbuf = file_pop_buffer(ms, pb);
417 		if (rv == -1) {
418 			free(rbuf);
419 			rbuf = NULL;
420 		}
421 		if ((ms->flags & MAGIC_DEBUG) != 0)
422 			(void)fprintf(stderr, "[try elf %d]\n", m);
423 	}
424 #endif
425 
426 	/* try soft magic tests */
427 	if ((ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
428 		m = file_softmagic(ms, &b, NULL, NULL, BINTEST, looks_text);
429 		if ((ms->flags & MAGIC_DEBUG) != 0)
430 			(void)fprintf(stderr, "[try softmagic %d]\n", m);
431 		if (m == 1 && rbuf) {
432 			if (file_printf(ms, "%s", rbuf) == -1)
433 				goto done;
434 		}
435 		if (m) {
436 			if (checkdone(ms, &rv))
437 				goto done;
438 		}
439 	}
440 
441 	/* try text properties */
442 	if ((ms->flags & MAGIC_NO_CHECK_TEXT) == 0) {
443 
444 		m = file_ascmagic(ms, &b, looks_text);
445 		if ((ms->flags & MAGIC_DEBUG) != 0)
446 			(void)fprintf(stderr, "[try ascmagic %d]\n", m);
447 		if (m) {
448 			goto done;
449 		}
450 	}
451 
452 simple:
453 	/* give up */
454 	if (m == 0) {
455 		m = 1;
456 		rv = file_default(ms, nb);
457 		if (rv == 0)
458 			if (file_printf(ms, "%s", def) == -1)
459 				rv = -1;
460 	}
461  done:
462 	if ((ms->flags & MAGIC_MIME_ENCODING) != 0) {
463 		if (ms->flags & MAGIC_MIME_TYPE)
464 			if (file_printf(ms, "; charset=") == -1)
465 				rv = -1;
466 		if (file_printf(ms, "%s", code_mime) == -1)
467 			rv = -1;
468 	}
469 #if HAVE_FORK
470  done_encoding:
471 #endif
472 	free(rbuf);
473 	buffer_fini(&b);
474 	if (rv)
475 		return rv;
476 
477 	return m;
478 }
479 #endif
480 
481 protected int
482 file_reset(struct magic_set *ms, int checkloaded)
483 {
484 	if (checkloaded && ms->mlist[0] == NULL) {
485 		file_error(ms, 0, "no magic files loaded");
486 		return -1;
487 	}
488 	file_clearbuf(ms);
489 	if (ms->o.pbuf) {
490 		free(ms->o.pbuf);
491 		ms->o.pbuf = NULL;
492 	}
493 	ms->event_flags &= ~EVENT_HAD_ERR;
494 	ms->error = -1;
495 	return 0;
496 }
497 
498 #define OCTALIFY(n, o)	\
499 	/*LINTED*/ \
500 	(void)(*(n)++ = '\\', \
501 	*(n)++ = ((CAST(uint32_t, *(o)) >> 6) & 3) + '0', \
502 	*(n)++ = ((CAST(uint32_t, *(o)) >> 3) & 7) + '0', \
503 	*(n)++ = ((CAST(uint32_t, *(o)) >> 0) & 7) + '0', \
504 	(o)++)
505 
506 protected const char *
507 file_getbuffer(struct magic_set *ms)
508 {
509 	char *pbuf, *op, *np;
510 	size_t psize, len;
511 
512 	if (ms->event_flags & EVENT_HAD_ERR)
513 		return NULL;
514 
515 	if (ms->flags & MAGIC_RAW)
516 		return ms->o.buf;
517 
518 	if (ms->o.buf == NULL)
519 		return NULL;
520 
521 	/* * 4 is for octal representation, + 1 is for NUL */
522 	len = strlen(ms->o.buf);
523 	if (len > (SIZE_MAX - 1) / 4) {
524 		file_oomem(ms, len);
525 		return NULL;
526 	}
527 	psize = len * 4 + 1;
528 	if ((pbuf = CAST(char *, realloc(ms->o.pbuf, psize))) == NULL) {
529 		file_oomem(ms, psize);
530 		return NULL;
531 	}
532 	ms->o.pbuf = pbuf;
533 
534 #if defined(HAVE_WCHAR_H) && defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)
535 	{
536 		mbstate_t state;
537 		wchar_t nextchar;
538 		int mb_conv = 1;
539 		size_t bytesconsumed;
540 		char *eop;
541 		(void)memset(&state, 0, sizeof(mbstate_t));
542 
543 		np = ms->o.pbuf;
544 		op = ms->o.buf;
545 		eop = op + len;
546 
547 		while (op < eop) {
548 			bytesconsumed = mbrtowc(&nextchar, op,
549 			    CAST(size_t, eop - op), &state);
550 			if (bytesconsumed == CAST(size_t, -1) ||
551 			    bytesconsumed == CAST(size_t, -2)) {
552 				mb_conv = 0;
553 				break;
554 			}
555 
556 			if (iswprint(nextchar)) {
557 				(void)memcpy(np, op, bytesconsumed);
558 				op += bytesconsumed;
559 				np += bytesconsumed;
560 			} else {
561 				while (bytesconsumed-- > 0)
562 					OCTALIFY(np, op);
563 			}
564 		}
565 		*np = '\0';
566 
567 		/* Parsing succeeded as a multi-byte sequence */
568 		if (mb_conv != 0)
569 			return ms->o.pbuf;
570 	}
571 #endif
572 
573 	for (np = ms->o.pbuf, op = ms->o.buf; *op;) {
574 		if (isprint(CAST(unsigned char, *op))) {
575 			*np++ = *op++;
576 		} else {
577 			OCTALIFY(np, op);
578 		}
579 	}
580 	*np = '\0';
581 	return ms->o.pbuf;
582 }
583 
584 protected int
585 file_check_mem(struct magic_set *ms, unsigned int level)
586 {
587 	size_t len;
588 
589 	if (level >= ms->c.len) {
590 		len = (ms->c.len = 20 + level) * sizeof(*ms->c.li);
591 		ms->c.li = CAST(struct level_info *, (ms->c.li == NULL) ?
592 		    malloc(len) :
593 		    realloc(ms->c.li, len));
594 		if (ms->c.li == NULL) {
595 			file_oomem(ms, len);
596 			return -1;
597 		}
598 	}
599 	ms->c.li[level].got_match = 0;
600 #ifdef ENABLE_CONDITIONALS
601 	ms->c.li[level].last_match = 0;
602 	ms->c.li[level].last_cond = COND_NONE;
603 #endif /* ENABLE_CONDITIONALS */
604 	return 0;
605 }
606 
607 protected size_t
608 file_printedlen(const struct magic_set *ms)
609 {
610 	return ms->o.blen;
611 }
612 
613 protected int
614 file_replace(struct magic_set *ms, const char *pat, const char *rep)
615 {
616 	file_regex_t rx;
617 	int rc, rv = -1;
618 
619 	rc = file_regcomp(&rx, pat, REG_EXTENDED);
620 	if (rc) {
621 		file_regerror(&rx, rc, ms);
622 	} else {
623 		regmatch_t rm;
624 		int nm = 0;
625 		while (file_regexec(&rx, ms->o.buf, 1, &rm, 0) == 0) {
626 			ms->o.buf[rm.rm_so] = '\0';
627 			if (file_printf(ms, "%s%s", rep,
628 			    rm.rm_eo != 0 ? ms->o.buf + rm.rm_eo : "") == -1)
629 				goto out;
630 			nm++;
631 		}
632 		rv = nm;
633 	}
634 out:
635 	file_regfree(&rx);
636 	return rv;
637 }
638 
639 protected int
640 file_regcomp(file_regex_t *rx, const char *pat, int flags)
641 {
642 #ifdef USE_C_LOCALE
643 	rx->c_lc_ctype = newlocale(LC_CTYPE_MASK, "C", 0);
644 	assert(rx->c_lc_ctype != NULL);
645 	rx->old_lc_ctype = uselocale(rx->c_lc_ctype);
646 	assert(rx->old_lc_ctype != NULL);
647 #else
648 	rx->old_lc_ctype = setlocale(LC_CTYPE, NULL);
649 	assert(rx->old_lc_ctype != NULL);
650 	rx->old_lc_ctype = strdup(rx->old_lc_ctype);
651 	assert(rx->old_lc_ctype != NULL);
652 	(void)setlocale(LC_CTYPE, "C");
653 #endif
654 	rx->pat = pat;
655 
656 	return rx->rc = regcomp(&rx->rx, pat, flags);
657 }
658 
659 protected int
660 file_regexec(file_regex_t *rx, const char *str, size_t nmatch,
661     regmatch_t* pmatch, int eflags)
662 {
663 	assert(rx->rc == 0);
664 	/* XXX: force initialization because glibc does not always do this */
665 	if (nmatch != 0)
666 		memset(pmatch, 0, nmatch * sizeof(*pmatch));
667 	return regexec(&rx->rx, str, nmatch, pmatch, eflags);
668 }
669 
670 protected void
671 file_regfree(file_regex_t *rx)
672 {
673 	if (rx->rc == 0)
674 		regfree(&rx->rx);
675 #ifdef USE_C_LOCALE
676 	(void)uselocale(rx->old_lc_ctype);
677 	freelocale(rx->c_lc_ctype);
678 #else
679 	(void)setlocale(LC_CTYPE, rx->old_lc_ctype);
680 	free(rx->old_lc_ctype);
681 #endif
682 }
683 
684 protected void
685 file_regerror(file_regex_t *rx, int rc, struct magic_set *ms)
686 {
687 	char errmsg[512];
688 
689 	(void)regerror(rc, &rx->rx, errmsg, sizeof(errmsg));
690 	file_magerror(ms, "regex error %d for `%s', (%s)", rc, rx->pat,
691 	    errmsg);
692 }
693 
694 protected file_pushbuf_t *
695 file_push_buffer(struct magic_set *ms)
696 {
697 	file_pushbuf_t *pb;
698 
699 	if (ms->event_flags & EVENT_HAD_ERR)
700 		return NULL;
701 
702 	if ((pb = (CAST(file_pushbuf_t *, malloc(sizeof(*pb))))) == NULL)
703 		return NULL;
704 
705 	pb->buf = ms->o.buf;
706 	pb->blen = ms->o.blen;
707 	pb->offset = ms->offset;
708 
709 	ms->o.buf = NULL;
710 	ms->o.blen = 0;
711 	ms->offset = 0;
712 
713 	return pb;
714 }
715 
716 protected char *
717 file_pop_buffer(struct magic_set *ms, file_pushbuf_t *pb)
718 {
719 	char *rbuf;
720 
721 	if (ms->event_flags & EVENT_HAD_ERR) {
722 		free(pb->buf);
723 		free(pb);
724 		return NULL;
725 	}
726 
727 	rbuf = ms->o.buf;
728 
729 	ms->o.buf = pb->buf;
730 	ms->o.blen = pb->blen;
731 	ms->offset = pb->offset;
732 
733 	free(pb);
734 	return rbuf;
735 }
736 
737 /*
738  * convert string to ascii printable format.
739  */
740 protected char *
741 file_printable(char *buf, size_t bufsiz, const char *str, size_t slen)
742 {
743 	char *ptr, *eptr = buf + bufsiz - 1;
744 	const unsigned char *s = RCAST(const unsigned char *, str);
745 	const unsigned char *es = s + slen;
746 
747 	for (ptr = buf;  ptr < eptr && s < es && *s; s++) {
748 		if (isprint(*s)) {
749 			*ptr++ = *s;
750 			continue;
751 		}
752 		if (ptr >= eptr - 3)
753 			break;
754 		*ptr++ = '\\';
755 		*ptr++ = ((CAST(unsigned int, *s) >> 6) & 7) + '0';
756 		*ptr++ = ((CAST(unsigned int, *s) >> 3) & 7) + '0';
757 		*ptr++ = ((CAST(unsigned int, *s) >> 0) & 7) + '0';
758 	}
759 	*ptr = '\0';
760 	return buf;
761 }
762 
763 struct guid {
764 	uint32_t data1;
765 	uint16_t data2;
766 	uint16_t data3;
767 	uint8_t data4[8];
768 };
769 
770 protected int
771 file_parse_guid(const char *s, uint64_t *guid)
772 {
773 	struct guid *g = CAST(struct guid *, CAST(void *, guid));
774 	return sscanf(s,
775 	    "%8x-%4hx-%4hx-%2hhx%2hhx-%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx",
776 	    &g->data1, &g->data2, &g->data3, &g->data4[0], &g->data4[1],
777 	    &g->data4[2], &g->data4[3], &g->data4[4], &g->data4[5],
778 	    &g->data4[6], &g->data4[7]) == 11 ? 0 : -1;
779 }
780 
781 protected int
782 file_print_guid(char *str, size_t len, const uint64_t *guid)
783 {
784 	const struct guid *g = CAST(const struct guid *,
785 	    CAST(const void *, guid));
786 
787 	return snprintf(str, len, "%.8X-%.4hX-%.4hX-%.2hhX%.2hhX-"
788 	    "%.2hhX%.2hhX%.2hhX%.2hhX%.2hhX%.2hhX",
789 	    g->data1, g->data2, g->data3, g->data4[0], g->data4[1],
790 	    g->data4[2], g->data4[3], g->data4[4], g->data4[5],
791 	    g->data4[6], g->data4[7]);
792 }
793