funcs.c revision 169962 
1/*
2 * Copyright (c) Christos Zoulas 2003.
3 * All Rights Reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice immediately at the beginning of the file, without modification,
10 *    this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
19 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27#include "file.h"
28#include "magic.h"
29#include <stdarg.h>
30#include <stdlib.h>
31#include <string.h>
32#include <ctype.h>
33#if defined(HAVE_WCHAR_H)
34#include <wchar.h>
35#endif
36#if defined(HAVE_WCTYPE_H)
37#include <wctype.h>
38#endif
39#if defined(HAVE_LIMITS_H)
40#include <limits.h>
41#endif
42#ifndef SIZE_T_MAX
43#ifdef __LP64__
44#define SIZE_T_MAX (size_t)0xfffffffffffffffffU
45#else
46#define SIZE_T_MAX (size_t)0xffffffffU
47#endif
48#endif
49
50#ifndef	lint
51FILE_RCSID("@(#)$File: funcs.c,v 1.32 2007/05/24 17:22:27 christos Exp $")
52#endif	/* lint */
53
54#ifndef HAVE_VSNPRINTF
55int vsnprintf(char *, size_t, const char *, va_list);
56#endif
57
58/*
59 * Like printf, only we print to a buffer and advance it.
60 */
61protected int
62file_printf(struct magic_set *ms, const char *fmt, ...)
63{
64	va_list ap;
65	size_t len, size;
66	char *buf;
67
68	va_start(ap, fmt);
69
70	if ((len = vsnprintf(ms->o.ptr, ms->o.left, fmt, ap)) >= ms->o.left) {
71		long diff;	/* XXX: really ptrdiff_t */
72
73		va_end(ap);
74		size = (ms->o.size - ms->o.left) + len + 1024;
75		if ((buf = realloc(ms->o.buf, size)) == NULL) {
76			file_oomem(ms, size);
77			return -1;
78		}
79		diff = ms->o.ptr - ms->o.buf;
80		ms->o.ptr = buf + diff;
81		ms->o.buf = buf;
82		ms->o.left = size - diff;
83		ms->o.size = size;
84
85		va_start(ap, fmt);
86		len = vsnprintf(ms->o.ptr, ms->o.left, fmt, ap);
87	}
88	va_end(ap);
89	ms->o.ptr += len;
90	ms->o.left -= len;
91	return 0;
92}
93
94/*
95 * error - print best error message possible
96 */
97/*VARARGS*/
98private void
99file_error_core(struct magic_set *ms, int error, const char *f, va_list va,
100    uint32_t lineno)
101{
102	size_t len;
103	/* Only the first error is ok */
104	if (ms->haderr)
105		return;
106	len = 0;
107	if (lineno != 0) {
108		(void)snprintf(ms->o.buf, ms->o.size, "line %u: ", lineno);
109		len = strlen(ms->o.buf);
110	}
111	(void)vsnprintf(ms->o.buf + len, ms->o.size - len, f, va);
112	if (error > 0) {
113		len = strlen(ms->o.buf);
114		(void)snprintf(ms->o.buf + len, ms->o.size - len, " (%s)",
115		    strerror(error));
116	}
117	ms->haderr++;
118	ms->error = error;
119}
120
121/*VARARGS*/
122protected void
123file_error(struct magic_set *ms, int error, const char *f, ...)
124{
125	va_list va;
126	va_start(va, f);
127	file_error_core(ms, error, f, va, 0);
128	va_end(va);
129}
130
131/*
132 * Print an error with magic line number.
133 */
134/*VARARGS*/
135protected void
136file_magerror(struct magic_set *ms, const char *f, ...)
137{
138	va_list va;
139	va_start(va, f);
140	file_error_core(ms, 0, f, va, ms->line);
141	va_end(va);
142}
143
144protected void
145file_oomem(struct magic_set *ms, size_t len)
146{
147	file_error(ms, errno, "cannot allocate %zu bytes", len);
148}
149
150protected void
151file_badseek(struct magic_set *ms)
152{
153	file_error(ms, errno, "error seeking");
154}
155
156protected void
157file_badread(struct magic_set *ms)
158{
159	file_error(ms, errno, "error reading");
160}
161
162#ifndef COMPILE_ONLY
163protected int
164file_buffer(struct magic_set *ms, int fd, const char *inname, const void *buf,
165    size_t nb)
166{
167    int m;
168
169#ifdef __EMX__
170    if ((ms->flags & MAGIC_NO_CHECK_APPTYPE) == 0 && inname) {
171	switch (file_os2_apptype(ms, inname, buf, nb)) {
172	case -1:
173	    return -1;
174	case 0:
175	    break;
176	default:
177	    return 1;
178	}
179    }
180#endif
181
182    /* try compression stuff */
183    if ((ms->flags & MAGIC_NO_CHECK_COMPRESS) != 0 ||
184        (m = file_zmagic(ms, fd, inname, buf, nb)) == 0) {
185	/* Check if we have a tar file */
186	if ((ms->flags & MAGIC_NO_CHECK_TAR) != 0 ||
187	    (m = file_is_tar(ms, buf, nb)) == 0) {
188	    /* try tests in /etc/magic (or surrogate magic file) */
189	    if ((ms->flags & MAGIC_NO_CHECK_SOFT) != 0 ||
190		(m = file_softmagic(ms, buf, nb)) == 0) {
191		/* try known keywords, check whether it is ASCII */
192		if ((ms->flags & MAGIC_NO_CHECK_ASCII) != 0 ||
193		    (m = file_ascmagic(ms, buf, nb)) == 0) {
194		    /* abandon hope, all ye who remain here */
195		    if (file_printf(ms, ms->flags & MAGIC_MIME ?
196			(nb ? "application/octet-stream" :
197			    "application/empty") :
198			(nb ? "data" :
199			    "empty")) == -1)
200			    return -1;
201		    m = 1;
202		}
203	    }
204	}
205    }
206#ifdef BUILTIN_ELF
207    if ((ms->flags & MAGIC_NO_CHECK_ELF) == 0 && m == 1 && nb > 5 && fd != -1) {
208	/*
209	 * We matched something in the file, so this *might*
210	 * be an ELF file, and the file is at least 5 bytes
211	 * long, so if it's an ELF file it has at least one
212	 * byte past the ELF magic number - try extracting
213	 * information from the ELF headers that cannot easily
214	 * be extracted with rules in the magic file.
215	 */
216	(void)file_tryelf(ms, fd, buf, nb);
217    }
218#endif
219    return m;
220}
221#endif
222
223protected int
224file_reset(struct magic_set *ms)
225{
226	if (ms->mlist == NULL) {
227		file_error(ms, 0, "no magic files loaded");
228		return -1;
229	}
230	ms->o.ptr = ms->o.buf;
231	ms->o.left = ms->o.size;
232	ms->haderr = 0;
233	ms->error = -1;
234	return 0;
235}
236
237#define OCTALIFY(n, o)	\
238	/*LINTED*/ \
239	(void)(*(n)++ = '\\', \
240	*(n)++ = (((uint32_t)*(o) >> 6) & 3) + '0', \
241	*(n)++ = (((uint32_t)*(o) >> 3) & 7) + '0', \
242	*(n)++ = (((uint32_t)*(o) >> 0) & 7) + '0', \
243	(o)++)
244
245protected const char *
246file_getbuffer(struct magic_set *ms)
247{
248	char *pbuf, *op, *np;
249	size_t psize, len;
250
251	if (ms->haderr)
252		return NULL;
253
254	if (ms->flags & MAGIC_RAW)
255		return ms->o.buf;
256
257	len = ms->o.size - ms->o.left;
258	/* * 4 is for octal representation, + 1 is for NUL */
259	if (len > (SIZE_T_MAX - 1) / 4) {
260		file_oomem(ms, len);
261		return NULL;
262	}
263	psize = len * 4 + 1;
264	if (ms->o.psize < psize) {
265		if ((pbuf = realloc(ms->o.pbuf, psize)) == NULL) {
266			file_oomem(ms, psize);
267			return NULL;
268		}
269		ms->o.psize = psize;
270		ms->o.pbuf = pbuf;
271	}
272
273#if defined(HAVE_WCHAR_H) && defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)
274	{
275		mbstate_t state;
276		wchar_t nextchar;
277		int mb_conv = 1;
278		size_t bytesconsumed;
279		char *eop;
280		(void)memset(&state, 0, sizeof(mbstate_t));
281
282		np = ms->o.pbuf;
283		op = ms->o.buf;
284		eop = op + strlen(ms->o.buf);
285
286		while (op < eop) {
287			bytesconsumed = mbrtowc(&nextchar, op,
288			    (size_t)(eop - op), &state);
289			if (bytesconsumed == (size_t)(-1) ||
290			    bytesconsumed == (size_t)(-2)) {
291				mb_conv = 0;
292				break;
293			}
294
295			if (iswprint(nextchar)) {
296				(void)memcpy(np, op, bytesconsumed);
297				op += bytesconsumed;
298				np += bytesconsumed;
299			} else {
300				while (bytesconsumed-- > 0)
301					OCTALIFY(np, op);
302			}
303		}
304		*np = '\0';
305
306		/* Parsing succeeded as a multi-byte sequence */
307		if (mb_conv != 0)
308			return ms->o.pbuf;
309	}
310#endif
311
312	for (np = ms->o.pbuf, op = ms->o.buf; *op; op++) {
313		if (isprint((unsigned char)*op)) {
314			*np++ = *op;
315		} else {
316			OCTALIFY(np, op);
317		}
318	}
319	*np = '\0';
320	return ms->o.pbuf;
321}
322
323protected int
324file_check_mem(struct magic_set *ms, unsigned int level)
325{
326	size_t len;
327
328	if (level >= ms->c.len) {
329		len = (ms->c.len += 20) * sizeof(*ms->c.li);
330		ms->c.li = (ms->c.li == NULL) ? malloc(len) :
331		    realloc(ms->c.li, len);
332		if (ms->c.li == NULL) {
333			file_oomem(ms, len);
334			return -1;
335		}
336	}
337	ms->c.li[level].got_match = 0;
338#ifdef ENABLE_CONDITIONALS
339	ms->c.li[level].last_match = 0;
340	ms->c.li[level].last_cond = COND_NONE;
341#endif /* ENABLE_CONDITIONALS */
342	return 0;
343}
344/*
345 * Yes these wrappers suffer from buffer overflows, but if your OS does not
346 * have the real functions, maybe you should consider replacing your OS?
347 */
348#ifndef HAVE_VSNPRINTF
349int
350vsnprintf(char *buf, size_t len, const char *fmt, va_list ap)
351{
352	return vsprintf(buf, fmt, ap);
353}
354#endif
355
356#ifndef HAVE_SNPRINTF
357/*ARGSUSED*/
358int
359snprintf(char *buf, size_t len, const char *fmt, ...)
360{
361	int rv;
362	va_list ap;
363	va_start(ap, fmt);
364	rv = vsprintf(buf, fmt, ap);
365	va_end(ap);
366	return rv;
367}
368#endif
369