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
28#ifdef WIN32
29#include <windows.h>
30#include <shlwapi.h>
31#endif
32
33#include "file.h"
34
35#ifndef	lint
36FILE_RCSID("@(#)$File: magic.c,v 1.74 2011/05/26 01:27:59 christos Exp $")
37#endif	/* lint */
38
39#include "magic.h"
40
41#include <stdlib.h>
42#include <unistd.h>
43#include <string.h>
44#ifdef QUICK
45#include <sys/mman.h>
46#endif
47#ifdef HAVE_LIMITS_H
48#include <limits.h>	/* for PIPE_BUF */
49#endif
50
51#if defined(HAVE_UTIMES)
52# include <sys/time.h>
53#elif defined(HAVE_UTIME)
54# if defined(HAVE_SYS_UTIME_H)
55#  include <sys/utime.h>
56# elif defined(HAVE_UTIME_H)
57#  include <utime.h>
58# endif
59#endif
60
61#ifdef HAVE_UNISTD_H
62#include <unistd.h>	/* for read() */
63#endif
64
65#ifndef PIPE_BUF
66/* Get the PIPE_BUF from pathconf */
67#ifdef _PC_PIPE_BUF
68#define PIPE_BUF pathconf(".", _PC_PIPE_BUF)
69#else
70#define PIPE_BUF 512
71#endif
72#endif
73
74private void free_mlist(struct mlist *);
75#ifndef COMPILE_ONLY
76private void close_and_restore(const struct magic_set *, const char *, int,
77    const struct stat *);
78private int unreadable_info(struct magic_set *, mode_t, const char *);
79private const char* get_default_magic(void);
80private const char *file_or_fd(struct magic_set *, const char *, int);
81#endif
82
83#ifndef	STDIN_FILENO
84#define	STDIN_FILENO	0
85#endif
86
87private const char *
88get_default_magic(void)
89{
90	static const char hmagic[] = "/.magic/magic.mgc";
91	static char *default_magic;
92	char *home, *hmagicpath;
93
94#ifndef WIN32
95	struct stat st;
96
97	if (default_magic) {
98		free(default_magic);
99		default_magic = NULL;
100	}
101	if ((home = getenv("HOME")) == NULL)
102		return MAGIC;
103
104	if (asprintf(&hmagicpath, "%s/.magic", home) < 0)
105		return MAGIC;
106	if (stat(hmagicpath, &st) == -1)
107		goto out;
108	if (S_ISDIR(st.st_mode)) {
109		free(hmagicpath);
110		if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0)
111			return MAGIC;
112		if (access(hmagicpath, R_OK) == -1)
113			goto out;
114	}
115
116	if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0)
117		goto out;
118	free(hmagicpath);
119	return default_magic;
120out:
121	default_magic = NULL;
122	free(hmagicpath);
123	return MAGIC;
124#else
125	char *hmagicp = hmagicpath;
126	char *tmppath = NULL;
127
128#define APPENDPATH() \
129	do { \
130		if (tmppath && access(tmppath, R_OK) != -1) { \
131			if (hmagicpath == NULL) \
132				hmagicpath = tmppath; \
133			else { \
134				if (asprintf(&hmagicp, "%s%c%s", hmagicpath, \
135				    PATHSEP, tmppath) >= 0) { \
136					free(hmagicpath); \
137					hmagicpath = hmagicp; \
138				} \
139				free(tmppath); \
140			} \
141			tmppath = NULL; \
142		} \
143	} while (/*CONSTCOND*/0)
144
145	if (default_magic) {
146		free(default_magic);
147		default_magic = NULL;
148	}
149
150	/* First, try to get user-specific magic file */
151	if ((home = getenv("LOCALAPPDATA")) == NULL) {
152		if ((home = getenv("USERPROFILE")) != NULL)
153			if (asprintf(&tmppath,
154			    "%s/Local Settings/Application Data%s", home,
155			    hmagic) < 0)
156				tmppath = NULL;
157	} else {
158		if (asprintf(&tmppath, "%s%s", home, hmagic) < 0)
159			tmppath = NULL;
160	}
161
162	APPENDPATH();
163
164	/* Second, try to get a magic file from Common Files */
165	if ((home = getenv("COMMONPROGRAMFILES")) != NULL) {
166		if (asprintf(&tmppath, "%s%s", home, hmagic) >= 0)
167			APPENDPATH();
168	}
169
170	/* Third, try to get magic file relative to dll location */
171	LPTSTR dllpath = malloc(sizeof(*dllpath) * (MAX_PATH + 1));
172	dllpath[MAX_PATH] = 0;	/* just in case long path gets truncated and not null terminated */
173	if (GetModuleFileNameA(NULL, dllpath, MAX_PATH)){
174		PathRemoveFileSpecA(dllpath);
175		if (strlen(dllpath) > 3 &&
176		    stricmp(&dllpath[strlen(dllpath) - 3], "bin") == 0) {
177			if (asprintf(&tmppath,
178			    "%s/../share/misc/magic.mgc", dllpath) >= 0)
179				APPENDPATH();
180		} else {
181			if (asprintf(&tmppath,
182			    "%s/share/misc/magic.mgc", dllpath) >= 0)
183				APPENDPATH();
184			else if (asprintf(&tmppath,
185			    "%s/magic.mgc", dllpath) >= 0)
186				APPENDPATH();
187		}
188	}
189
190	/* Don't put MAGIC constant - it likely points to a file within MSys
191	tree */
192	default_magic = hmagicpath;
193	return default_magic;
194#endif
195}
196
197public const char *
198magic_getpath(const char *magicfile, int action)
199{
200	if (magicfile != NULL)
201		return magicfile;
202
203	magicfile = getenv("MAGIC");
204	if (magicfile != NULL)
205		return magicfile;
206
207	return action == FILE_LOAD ? get_default_magic() : MAGIC;
208}
209
210public struct magic_set *
211magic_open(int flags)
212{
213	struct magic_set *ms;
214	size_t len;
215
216	if ((ms = CAST(struct magic_set *, calloc((size_t)1,
217	    sizeof(struct magic_set)))) == NULL)
218		return NULL;
219
220	if (magic_setflags(ms, flags) == -1) {
221		errno = EINVAL;
222		goto free;
223	}
224
225	ms->o.buf = ms->o.pbuf = NULL;
226	len = (ms->c.len = 10) * sizeof(*ms->c.li);
227
228	if ((ms->c.li = CAST(struct level_info *, malloc(len))) == NULL)
229		goto free;
230
231	ms->event_flags = 0;
232	ms->error = -1;
233	ms->mlist = NULL;
234	ms->file = "unknown";
235	ms->line = 0;
236	return ms;
237free:
238	free(ms);
239	return NULL;
240}
241
242private void
243free_mlist(struct mlist *mlist)
244{
245	struct mlist *ml;
246
247	if (mlist == NULL)
248		return;
249
250	for (ml = mlist->next; ml != mlist;) {
251		struct mlist *next = ml->next;
252		struct magic *mg = ml->magic;
253		file_delmagic(mg, ml->mapped, ml->nmagic);
254		free(ml);
255		ml = next;
256	}
257	free(ml);
258}
259
260#ifndef COMPILE_ONLY
261private int
262unreadable_info(struct magic_set *ms, mode_t md, const char *file)
263{
264	/* We cannot open it, but we were able to stat it. */
265	if (access(file, W_OK) == 0)
266		if (file_printf(ms, "writable, ") == -1)
267			return -1;
268	if (access(file, X_OK) == 0)
269		if (file_printf(ms, "executable, ") == -1)
270			return -1;
271	if (S_ISREG(md))
272		if (file_printf(ms, "regular file, ") == -1)
273			return -1;
274	if (file_printf(ms, "no read permission") == -1)
275		return -1;
276	return 0;
277}
278#endif
279
280public void
281magic_close(struct magic_set *ms)
282{
283	free_mlist(ms->mlist);
284	free(ms->o.pbuf);
285	free(ms->o.buf);
286	free(ms->c.li);
287	free(ms);
288}
289
290/*
291 * load a magic file
292 */
293public int
294magic_load(struct magic_set *ms, const char *magicfile)
295{
296	struct mlist *ml = file_apprentice(ms, magicfile, FILE_LOAD);
297	if (ml) {
298		free_mlist(ms->mlist);
299		ms->mlist = ml;
300		return 0;
301	}
302	return -1;
303}
304
305public int
306magic_compile(struct magic_set *ms, const char *magicfile)
307{
308	struct mlist *ml = file_apprentice(ms, magicfile, FILE_COMPILE);
309	free_mlist(ml);
310	return ml ? 0 : -1;
311}
312
313public int
314magic_check(struct magic_set *ms, const char *magicfile)
315{
316	struct mlist *ml = file_apprentice(ms, magicfile, FILE_CHECK);
317	free_mlist(ml);
318	return ml ? 0 : -1;
319}
320
321public int
322magic_list(struct magic_set *ms, const char *magicfile)
323{
324	struct mlist *ml = file_apprentice(ms, magicfile, FILE_LIST);
325	free_mlist(ml);
326	return ml ? 0 : -1;
327}
328
329#ifndef COMPILE_ONLY
330private void
331close_and_restore(const struct magic_set *ms, const char *name, int fd,
332    const struct stat *sb)
333{
334	if (fd == STDIN_FILENO)
335		return;
336	(void) close(fd);
337
338	if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) {
339		/*
340		 * Try to restore access, modification times if read it.
341		 * This is really *bad* because it will modify the status
342		 * time of the file... And of course this will affect
343		 * backup programs
344		 */
345#ifdef HAVE_UTIMES
346		struct timeval  utsbuf[2];
347		(void)memset(utsbuf, 0, sizeof(utsbuf));
348		utsbuf[0].tv_sec = sb->st_atime;
349		utsbuf[1].tv_sec = sb->st_mtime;
350
351		(void) utimes(name, utsbuf); /* don't care if loses */
352#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H)
353		struct utimbuf  utbuf;
354
355		(void)memset(&utbuf, 0, sizeof(utbuf));
356		utbuf.actime = sb->st_atime;
357		utbuf.modtime = sb->st_mtime;
358		(void) utime(name, &utbuf); /* don't care if loses */
359#endif
360	}
361}
362
363
364/*
365 * find type of descriptor
366 */
367public const char *
368magic_descriptor(struct magic_set *ms, int fd)
369{
370	return file_or_fd(ms, NULL, fd);
371}
372
373/*
374 * find type of named file
375 */
376public const char *
377magic_file(struct magic_set *ms, const char *inname)
378{
379	return file_or_fd(ms, inname, STDIN_FILENO);
380}
381
382private const char *
383file_or_fd(struct magic_set *ms, const char *inname, int fd)
384{
385	int	rv = -1;
386	unsigned char *buf;
387	struct stat	sb;
388	ssize_t nbytes = 0;	/* number of bytes read from a datafile */
389	int	ispipe = 0;
390
391	/*
392	 * one extra for terminating '\0', and
393	 * some overlapping space for matches near EOF
394	 */
395#define SLOP (1 + sizeof(union VALUETYPE))
396	if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL)
397		return NULL;
398
399	if (file_reset(ms) == -1)
400		goto done;
401
402	switch (file_fsmagic(ms, inname, &sb)) {
403	case -1:		/* error */
404		goto done;
405	case 0:			/* nothing found */
406		break;
407	default:		/* matched it and printed type */
408		rv = 0;
409		goto done;
410	}
411
412	if (inname == NULL) {
413		if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode))
414			ispipe = 1;
415	} else {
416		int flags = O_RDONLY|O_BINARY;
417
418		if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) {
419#ifdef O_NONBLOCK
420			flags |= O_NONBLOCK;
421#endif
422			ispipe = 1;
423		}
424
425		errno = 0;
426		if ((fd = open(inname, flags)) < 0) {
427			if (unreadable_info(ms, sb.st_mode, inname) == -1)
428				goto done;
429			rv = 0;
430			goto done;
431		}
432#ifdef O_NONBLOCK
433		if ((flags = fcntl(fd, F_GETFL)) != -1) {
434			flags &= ~O_NONBLOCK;
435			(void)fcntl(fd, F_SETFL, flags);
436		}
437#endif
438	}
439
440	/*
441	 * try looking at the first HOWMANY bytes
442	 */
443	if (ispipe) {
444		ssize_t r = 0;
445
446		while ((r = sread(fd, (void *)&buf[nbytes],
447		    (size_t)(HOWMANY - nbytes), 1)) > 0) {
448			nbytes += r;
449			if (r < PIPE_BUF) break;
450		}
451
452		if (nbytes == 0) {
453			/* We can not read it, but we were able to stat it. */
454			if (unreadable_info(ms, sb.st_mode, inname) == -1)
455				goto done;
456			rv = 0;
457			goto done;
458		}
459
460	} else {
461		if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) {
462			file_error(ms, errno, "cannot read `%s'", inname);
463			goto done;
464		}
465	}
466
467	(void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */
468	if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1)
469		goto done;
470	rv = 0;
471done:
472	free(buf);
473	close_and_restore(ms, inname, fd, &sb);
474	return rv == 0 ? file_getbuffer(ms) : NULL;
475}
476
477
478public const char *
479magic_buffer(struct magic_set *ms, const void *buf, size_t nb)
480{
481	if (file_reset(ms) == -1)
482		return NULL;
483	/*
484	 * The main work is done here!
485	 * We have the file name and/or the data buffer to be identified.
486	 */
487	if (file_buffer(ms, -1, NULL, buf, nb) == -1) {
488		return NULL;
489	}
490	return file_getbuffer(ms);
491}
492#endif /* COMPILE_ONLY */
493
494public const char *
495magic_error(struct magic_set *ms)
496{
497	return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL;
498}
499
500public int
501magic_errno(struct magic_set *ms)
502{
503	return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0;
504}
505
506public int
507magic_setflags(struct magic_set *ms, int flags)
508{
509#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES)
510	if (flags & MAGIC_PRESERVE_ATIME)
511		return -1;
512#endif
513	ms->flags = flags;
514	return 0;
515}
516