1 /* $OpenBSD: magic.c,v 1.3 2007/07/09 16:39:48 dim Exp $ */
2 /*
3 * Copyright © 2013
4 * Thorsten “mirabilos” Glaser <tg@mirbsd.org>
5 * Copyright (c) Christos Zoulas 2003.
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 * 1. Redistributions of source code must retain the above copyright
12 * notice immediately at the beginning of the file, without modification,
13 * this list of conditions, and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote products
18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
24 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include "file.h"
34 #include "magic.h"
35
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <unistd.h>
39 #include <string.h>
40 #include <sys/types.h>
41 #include <sys/param.h> /* for MAXPATHLEN */
42 #include <sys/stat.h>
43 #include <fcntl.h> /* for open() */
44 #ifdef QUICK
45 #include <sys/mman.h>
46 #endif
47
48 #if defined(HAVE_UTIME)
49 # if defined(HAVE_SYS_UTIME_H)
50 # include <sys/utime.h>
51 # elif defined(HAVE_UTIME_H)
52 # include <utime.h>
53 # endif
54 #elif defined(HAVE_UTIMES)
55 # include <sys/time.h>
56 #endif
57
58 #ifdef HAVE_UNISTD_H
59 #include <unistd.h> /* for read() */
60 #endif
61
62 #ifdef HAVE_LOCALE_H
63 #include <locale.h>
64 #endif
65
66 #include <netinet/in.h> /* for byte swapping */
67
68 #include "patchlevel.h"
69
70 __RCSID("$MirOS: src/usr.bin/file/magic.c,v 1.3 2013/10/31 20:07:02 tg Exp $");
71
72 #ifdef __EMX__
73 private char *apptypeName = NULL;
74 protected int file_os2_apptype(struct magic_set *ms, const char *fn,
75 const void *buf, size_t nb);
76 #endif /* __EMX__ */
77
78 private void free_mlist(struct mlist *);
79 private void close_and_restore(const struct magic_set *, const char *, int,
80 const struct stat *);
81
82 public struct magic_set *
magic_open(int flags)83 magic_open(int flags)
84 {
85 struct magic_set *ms;
86
87 if ((ms = malloc(sizeof(struct magic_set))) == NULL)
88 return NULL;
89
90 if (magic_setflags(ms, flags) == -1) {
91 free(ms);
92 errno = EINVAL;
93 return NULL;
94 }
95
96 ms->o.ptr = ms->o.buf = malloc(ms->o.left = ms->o.size = 1024);
97 if (ms->o.buf == NULL) {
98 free(ms);
99 return NULL;
100 }
101 ms->o.pbuf = malloc(ms->o.psize = 1024);
102 if (ms->o.pbuf == NULL) {
103 free(ms->o.buf);
104 free(ms);
105 return NULL;
106 }
107 ms->c.off = malloc((ms->c.len = 10) * sizeof(*ms->c.off));
108 if (ms->c.off == NULL) {
109 free(ms->o.pbuf);
110 free(ms->o.buf);
111 free(ms);
112 return NULL;
113 }
114 ms->haderr = 0;
115 ms->error = -1;
116 ms->mlist = NULL;
117 return ms;
118 }
119
120 private void
free_mlist(struct mlist * mlist)121 free_mlist(struct mlist *mlist)
122 {
123 struct mlist *ml;
124
125 if (mlist == NULL)
126 return;
127
128 for (ml = mlist->next; ml != mlist;) {
129 struct mlist *next = ml->next;
130 struct magic *mg = ml->magic;
131 file_delmagic(mg, ml->mapped, ml->nmagic);
132 free(ml);
133 ml = next;
134 }
135 free(ml);
136 }
137
138 public void
magic_close(struct magic_set * ms)139 magic_close(struct magic_set *ms)
140 {
141 free_mlist(ms->mlist);
142 free(ms->o.buf);
143 free(ms->c.off);
144 free(ms);
145 }
146
147 /*
148 * load a magic file
149 */
150 public int
magic_load(struct magic_set * ms,const char * magicfile)151 magic_load(struct magic_set *ms, const char *magicfile)
152 {
153 struct mlist *ml = file_apprentice(ms, magicfile, FILE_LOAD);
154 if (ml) {
155 free_mlist(ms->mlist);
156 ms->mlist = ml;
157 return 0;
158 }
159 return -1;
160 }
161
162 public int
magic_compile(struct magic_set * ms,const char * magicfile)163 magic_compile(struct magic_set *ms, const char *magicfile)
164 {
165 struct mlist *ml = file_apprentice(ms, magicfile, FILE_COMPILE);
166 free_mlist(ml);
167 return ml ? 0 : -1;
168 }
169
170 public int
magic_check(struct magic_set * ms,const char * magicfile)171 magic_check(struct magic_set *ms, const char *magicfile)
172 {
173 struct mlist *ml = file_apprentice(ms, magicfile, FILE_CHECK);
174 free_mlist(ml);
175 return ml ? 0 : -1;
176 }
177
178 private void
close_and_restore(const struct magic_set * ms,const char * name,int fd,const struct stat * sb)179 close_and_restore(const struct magic_set *ms,
180 const char *name __attribute__((__unused__)), int fd,
181 const struct stat *sb __attribute__((__unused__)))
182 {
183 (void) close(fd);
184 if (fd != STDIN_FILENO && (ms->flags & MAGIC_PRESERVE_ATIME) != 0) {
185 /*
186 * Try to restore access, modification times if read it.
187 * This is really *bad* because it will modify the status
188 * time of the file... And of course this will affect
189 * backup programs
190 */
191 #ifdef HAVE_UTIMES
192 struct timeval utsbuf[2];
193 utsbuf[0].tv_sec = sb->st_atime;
194 utsbuf[1].tv_sec = sb->st_mtime;
195
196 (void) utimes(name, utsbuf); /* don't care if loses */
197 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H)
198 struct utimbuf utbuf;
199
200 utbuf.actime = sb->st_atime;
201 utbuf.modtime = sb->st_mtime;
202 (void) utime(name, &utbuf); /* don't care if loses */
203 #endif
204 }
205 }
206
207 /*
208 * find type of named file
209 */
210 public const char *
magic_file(struct magic_set * ms,const char * inname)211 magic_file(struct magic_set *ms, const char *inname)
212 {
213 int fd = 0;
214 unsigned char buf[HOWMANY+1]; /* one extra for terminating '\0' */
215 struct stat sb;
216 ssize_t nbytes = 0; /* number of bytes read from a datafile */
217
218 if (file_reset(ms) == -1)
219 return NULL;
220
221 switch (file_fsmagic(ms, inname, &sb)) {
222 case -1:
223 return NULL;
224 case 0:
225 break;
226 default:
227 return file_getbuffer(ms);
228 }
229
230 #ifndef STDIN_FILENO
231 #define STDIN_FILENO 0
232 #endif
233 if (inname == NULL)
234 fd = STDIN_FILENO;
235 else if ((fd = open(inname, O_RDONLY)) < 0) {
236 /* We cannot open it, but we were able to stat it. */
237 if (sb.st_mode & 0222)
238 if (file_printf(ms, "writable, ") == -1)
239 return NULL;
240 if (sb.st_mode & 0111)
241 if (file_printf(ms, "executable, ") == -1)
242 return NULL;
243 if (S_ISREG(sb.st_mode))
244 if (file_printf(ms, "regular file, ") == -1)
245 return NULL;
246 if (file_printf(ms, "no read permission") == -1)
247 return NULL;
248 return file_getbuffer(ms);
249 }
250
251 /*
252 * try looking at the first HOWMANY bytes
253 */
254 if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) {
255 file_error(ms, errno, "cannot read `%s'", inname);
256 goto done;
257 }
258
259 if (nbytes == 0) {
260 if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
261 "application/x-empty" : "empty") == -1)
262 goto done;
263 goto gotit;
264 } else if (nbytes == 1) {
265 if (file_printf(ms, "very short file (no magic)") == -1)
266 goto done;
267 goto gotit;
268 } else {
269 buf[nbytes] = '\0'; /* null-terminate it */
270 #ifdef __EMX__
271 switch (file_os2_apptype(ms, inname, buf, nbytes)) {
272 case -1:
273 goto done;
274 case 0:
275 break;
276 default:
277 goto gotit;
278 }
279 #endif
280 if (file_buffer(ms, buf, (size_t)nbytes) == -1)
281 goto done;
282 #ifdef BUILTIN_ELF
283 if (nbytes > 5) {
284 /*
285 * We matched something in the file, so this *might*
286 * be an ELF file, and the file is at least 5 bytes
287 * long, so if it's an ELF file it has at least one
288 * byte past the ELF magic number - try extracting
289 * information from the ELF headers that cannot easily
290 * be extracted with rules in the magic file.
291 */
292 file_tryelf(ms, fd, buf, (size_t)nbytes);
293 }
294 #endif
295 }
296 gotit:
297 close_and_restore(ms, inname, fd, &sb);
298 return file_getbuffer(ms);
299 done:
300 close_and_restore(ms, inname, fd, &sb);
301 return NULL;
302 }
303
304
305 public const char *
magic_buffer(struct magic_set * ms,const void * buf,size_t nb)306 magic_buffer(struct magic_set *ms, const void *buf, size_t nb)
307 {
308 if (file_reset(ms) == -1)
309 return NULL;
310 /*
311 * The main work is done here!
312 * We have the file name and/or the data buffer to be identified.
313 */
314 if (file_buffer(ms, buf, nb) == -1) {
315 return NULL;
316 }
317 return file_getbuffer(ms);
318 }
319
320 public const char *
magic_error(struct magic_set * ms)321 magic_error(struct magic_set *ms)
322 {
323 return ms->haderr ? ms->o.buf : NULL;
324 }
325
326 public int
magic_errno(struct magic_set * ms)327 magic_errno(struct magic_set *ms)
328 {
329 return ms->haderr ? ms->error : 0;
330 }
331
332 public int
magic_setflags(struct magic_set * ms,int flags)333 magic_setflags(struct magic_set *ms, int flags)
334 {
335 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES)
336 if (flags & MAGIC_PRESERVE_ATIME)
337 return -1;
338 #endif
339 ms->flags = flags;
340 return 0;
341 }
342