xref: /freebsd/contrib/file/src/fsmagic.c (revision 596596fec79f04e1f413850b44159224ff1fb8dc)
1 /*
2  * Copyright (c) Ian F. Darwin 1986-1995.
3  * Software written by Ian F. Darwin and others;
4  * maintained 1995-present by Christos Zoulas and others.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice immediately at the beginning of the file, without modification,
11  *    this list of conditions, and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 /*
29  * fsmagic - magic based on filesystem info - directory, special files, etc.
30  */
31 
32 #include "file.h"
33 
34 #ifndef	lint
35 FILE_RCSID("@(#)$File: fsmagic.c,v 1.75 2014/12/04 15:56:46 christos Exp $")
36 #endif	/* lint */
37 
38 #include "magic.h"
39 #include <string.h>
40 #ifdef HAVE_UNISTD_H
41 #include <unistd.h>
42 #endif
43 #include <stdlib.h>
44 /* Since major is a function on SVR4, we cannot use `ifndef major'.  */
45 #ifdef MAJOR_IN_MKDEV
46 # include <sys/mkdev.h>
47 # define HAVE_MAJOR
48 #endif
49 #ifdef MAJOR_IN_SYSMACROS
50 # include <sys/sysmacros.h>
51 # define HAVE_MAJOR
52 #endif
53 #ifdef major			/* Might be defined in sys/types.h.  */
54 # define HAVE_MAJOR
55 #endif
56 #ifdef WIN32
57 # define WIN32_LEAN_AND_MEAN
58 # include <windows.h>
59 #endif
60 
61 #ifndef HAVE_MAJOR
62 # define major(dev)  (((dev) >> 8) & 0xff)
63 # define minor(dev)  ((dev) & 0xff)
64 #endif
65 #undef HAVE_MAJOR
66 #ifdef	S_IFLNK
67 private int
68 bad_link(struct magic_set *ms, int err, char *buf)
69 {
70 	int mime = ms->flags & MAGIC_MIME;
71 	if ((mime & MAGIC_MIME_TYPE) &&
72 	    file_printf(ms, "inode/symlink")
73 	    == -1)
74 		return -1;
75 	else if (!mime) {
76 		if (ms->flags & MAGIC_ERROR) {
77 			file_error(ms, err,
78 				   "broken symbolic link to %s", buf);
79 			return -1;
80 		}
81 		if (file_printf(ms, "broken symbolic link to %s", buf) == -1)
82 			return -1;
83 	}
84 	return 1;
85 }
86 #endif
87 private int
88 handle_mime(struct magic_set *ms, int mime, const char *str)
89 {
90 	if ((mime & MAGIC_MIME_TYPE)) {
91 		if (file_printf(ms, "inode/%s", str) == -1)
92 			return -1;
93 		if ((mime & MAGIC_MIME_ENCODING) && file_printf(ms,
94 		    "; charset=") == -1)
95 			return -1;
96 	}
97 	if ((mime & MAGIC_MIME_ENCODING) && file_printf(ms, "binary") == -1)
98 		return -1;
99 	return 0;
100 }
101 
102 protected int
103 file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb)
104 {
105 	int ret, did = 0;
106 	int mime = ms->flags & MAGIC_MIME;
107 #ifdef	S_IFLNK
108 	char buf[BUFSIZ+4];
109 	ssize_t nch;
110 	struct stat tstatbuf;
111 #endif
112 
113 	if (ms->flags & MAGIC_APPLE)
114 		return 0;
115 	if (fn == NULL)
116 		return 0;
117 
118 #define COMMA	(did++ ? ", " : "")
119 	/*
120 	 * Fstat is cheaper but fails for files you don't have read perms on.
121 	 * On 4.2BSD and similar systems, use lstat() to identify symlinks.
122 	 */
123 #ifdef	S_IFLNK
124 	if ((ms->flags & MAGIC_SYMLINK) == 0)
125 		ret = lstat(fn, sb);
126 	else
127 #endif
128 	ret = stat(fn, sb);	/* don't merge into if; see "ret =" above */
129 
130 #ifdef WIN32
131 	{
132 		HANDLE hFile = CreateFile((LPCSTR)fn, 0, FILE_SHARE_DELETE |
133 		    FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0,
134 		    NULL);
135 		if (hFile != INVALID_HANDLE_VALUE) {
136 			/*
137 			 * Stat failed, but we can still open it - assume it's
138 			 * a block device, if nothing else.
139 			 */
140 			if (ret) {
141 				sb->st_mode = S_IFBLK;
142 				ret = 0;
143 			}
144 			switch (GetFileType(hFile)) {
145 			case FILE_TYPE_CHAR:
146 				sb->st_mode |= S_IFCHR;
147 				sb->st_mode &= ~S_IFREG;
148 				break;
149 			case FILE_TYPE_PIPE:
150 				sb->st_mode |= S_IFIFO;
151 				sb->st_mode &= ~S_IFREG;
152 				break;
153 			}
154 			CloseHandle(hFile);
155 		}
156 	}
157 #endif
158 
159 	if (ret) {
160 		if (ms->flags & MAGIC_ERROR) {
161 			file_error(ms, errno, "cannot stat `%s'", fn);
162 			return -1;
163 		}
164 		if (file_printf(ms, "cannot open `%s' (%s)",
165 		    fn, strerror(errno)) == -1)
166 			return -1;
167 		return 0;
168 	}
169 
170 	ret = 1;
171 	if (!mime) {
172 #ifdef S_ISUID
173 		if (sb->st_mode & S_ISUID)
174 			if (file_printf(ms, "%ssetuid", COMMA) == -1)
175 				return -1;
176 #endif
177 #ifdef S_ISGID
178 		if (sb->st_mode & S_ISGID)
179 			if (file_printf(ms, "%ssetgid", COMMA) == -1)
180 				return -1;
181 #endif
182 #ifdef S_ISVTX
183 		if (sb->st_mode & S_ISVTX)
184 			if (file_printf(ms, "%ssticky", COMMA) == -1)
185 				return -1;
186 #endif
187 	}
188 
189 	switch (sb->st_mode & S_IFMT) {
190 	case S_IFDIR:
191 		if (mime) {
192 			if (handle_mime(ms, mime, "directory") == -1)
193 				return -1;
194 		} else if (file_printf(ms, "%sdirectory", COMMA) == -1)
195 			return -1;
196 		break;
197 #ifdef S_IFCHR
198 	case S_IFCHR:
199 		/*
200 		 * If -s has been specified, treat character special files
201 		 * like ordinary files.  Otherwise, just report that they
202 		 * are block special files and go on to the next file.
203 		 */
204 		if ((ms->flags & MAGIC_DEVICES) != 0) {
205 			ret = 0;
206 			break;
207 		}
208 		if (mime) {
209 			if (handle_mime(ms, mime, "chardevice") == -1)
210 				return -1;
211 		} else {
212 #ifdef HAVE_STRUCT_STAT_ST_RDEV
213 # ifdef dv_unit
214 			if (file_printf(ms, "%scharacter special (%d/%d/%d)",
215 			    COMMA, major(sb->st_rdev), dv_unit(sb->st_rdev),
216 					dv_subunit(sb->st_rdev)) == -1)
217 				return -1;
218 # else
219 			if (file_printf(ms, "%scharacter special (%ld/%ld)",
220 			    COMMA, (long)major(sb->st_rdev),
221 			    (long)minor(sb->st_rdev)) == -1)
222 				return -1;
223 # endif
224 #else
225 			if (file_printf(ms, "%scharacter special", COMMA) == -1)
226 				return -1;
227 #endif
228 		}
229 		break;
230 #endif
231 #ifdef S_IFBLK
232 	case S_IFBLK:
233 		/*
234 		 * If -s has been specified, treat block special files
235 		 * like ordinary files.  Otherwise, just report that they
236 		 * are block special files and go on to the next file.
237 		 */
238 		if ((ms->flags & MAGIC_DEVICES) != 0) {
239 			ret = 0;
240 			break;
241 		}
242 		if (mime) {
243 			if (handle_mime(ms, mime, "blockdevice") == -1)
244 				return -1;
245 		} else {
246 #ifdef HAVE_STRUCT_STAT_ST_RDEV
247 # ifdef dv_unit
248 			if (file_printf(ms, "%sblock special (%d/%d/%d)",
249 			    COMMA, major(sb->st_rdev), dv_unit(sb->st_rdev),
250 			    dv_subunit(sb->st_rdev)) == -1)
251 				return -1;
252 # else
253 			if (file_printf(ms, "%sblock special (%ld/%ld)",
254 			    COMMA, (long)major(sb->st_rdev),
255 			    (long)minor(sb->st_rdev)) == -1)
256 				return -1;
257 # endif
258 #else
259 			if (file_printf(ms, "%sblock special", COMMA) == -1)
260 				return -1;
261 #endif
262 		}
263 		break;
264 #endif
265 	/* TODO add code to handle V7 MUX and Blit MUX files */
266 #ifdef	S_IFIFO
267 	case S_IFIFO:
268 		if((ms->flags & MAGIC_DEVICES) != 0)
269 			break;
270 		if (mime) {
271 			if (handle_mime(ms, mime, "fifo") == -1)
272 				return -1;
273 		} else if (file_printf(ms, "%sfifo (named pipe)", COMMA) == -1)
274 			return -1;
275 		break;
276 #endif
277 #ifdef	S_IFDOOR
278 	case S_IFDOOR:
279 		if (mime) {
280 			if (handle_mime(ms, mime, "door") == -1)
281 				return -1;
282 		} else if (file_printf(ms, "%sdoor", COMMA) == -1)
283 			return -1;
284 		break;
285 #endif
286 #ifdef	S_IFLNK
287 	case S_IFLNK:
288 		if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
289 			if (ms->flags & MAGIC_ERROR) {
290 			    file_error(ms, errno, "unreadable symlink `%s'",
291 				fn);
292 			    return -1;
293 			}
294 			if (mime) {
295 				if (handle_mime(ms, mime, "symlink") == -1)
296 					return -1;
297 			} else if (file_printf(ms,
298 			    "%sunreadable symlink `%s' (%s)", COMMA, fn,
299 			    strerror(errno)) == -1)
300 				return -1;
301 			break;
302 		}
303 		buf[nch] = '\0';	/* readlink(2) does not do this */
304 
305 		/* If broken symlink, say so and quit early. */
306 		if (*buf == '/') {
307 			if (stat(buf, &tstatbuf) < 0)
308 				return bad_link(ms, errno, buf);
309 		} else {
310 			char *tmp;
311 			char buf2[BUFSIZ+BUFSIZ+4];
312 
313 			if ((tmp = strrchr(fn,  '/')) == NULL) {
314 				tmp = buf; /* in current directory anyway */
315 			} else {
316 				if (tmp - fn + 1 > BUFSIZ) {
317 					if (ms->flags & MAGIC_ERROR) {
318 						file_error(ms, 0,
319 						    "path too long: `%s'", buf);
320 						return -1;
321 					}
322 					if (mime) {
323 						if (handle_mime(ms, mime,
324 						    "x-path-too-long") == -1)
325 							return -1;
326 					} else if (file_printf(ms,
327 					    "%spath too long: `%s'", COMMA,
328 					    fn) == -1)
329 						return -1;
330 					break;
331 				}
332 				/* take dir part */
333 				(void)strlcpy(buf2, fn, sizeof buf2);
334 				buf2[tmp - fn + 1] = '\0';
335 				/* plus (rel) link */
336 				(void)strlcat(buf2, buf, sizeof buf2);
337 				tmp = buf2;
338 			}
339 			if (stat(tmp, &tstatbuf) < 0)
340 				return bad_link(ms, errno, buf);
341 		}
342 
343 		/* Otherwise, handle it. */
344 		if ((ms->flags & MAGIC_SYMLINK) != 0) {
345 			const char *p;
346 			ms->flags &= MAGIC_SYMLINK;
347 			p = magic_file(ms, buf);
348 			ms->flags |= MAGIC_SYMLINK;
349 			if (p == NULL)
350 				return -1;
351 		} else { /* just print what it points to */
352 			if (mime) {
353 				if (handle_mime(ms, mime, "symlink") == -1)
354 					return -1;
355 			} else if (file_printf(ms, "%ssymbolic link to %s",
356 			    COMMA, buf) == -1)
357 				return -1;
358 		}
359 		break;
360 #endif
361 #ifdef	S_IFSOCK
362 #ifndef __COHERENT__
363 	case S_IFSOCK:
364 		if (mime) {
365 			if (handle_mime(ms, mime, "socket") == -1)
366 				return -1;
367 		} else if (file_printf(ms, "%ssocket", COMMA) == -1)
368 			return -1;
369 		break;
370 #endif
371 #endif
372 	case S_IFREG:
373 		/*
374 		 * regular file, check next possibility
375 		 *
376 		 * If stat() tells us the file has zero length, report here that
377 		 * the file is empty, so we can skip all the work of opening and
378 		 * reading the file.
379 		 * But if the -s option has been given, we skip this
380 		 * optimization, since on some systems, stat() reports zero
381 		 * size for raw disk partitions. (If the block special device
382 		 * really has zero length, the fact that it is empty will be
383 		 * detected and reported correctly when we read the file.)
384 		 */
385 		if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
386 			if (mime) {
387 				if (handle_mime(ms, mime, "x-empty") == -1)
388 					return -1;
389 			} else if (file_printf(ms, "%sempty", COMMA) == -1)
390 				return -1;
391 			break;
392 		}
393 		ret = 0;
394 		break;
395 
396 	default:
397 		file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
398 		return -1;
399 		/*NOTREACHED*/
400 	}
401 
402 	if (!mime && did && ret == 0) {
403 	    if (file_printf(ms, " ") == -1)
404 		    return -1;
405 	}
406 	return ret;
407 }
408