fsmagic.c revision 191736 
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
35FILE_RCSID("@(#)$File: fsmagic.c,v 1.59 2009/02/03 20:27:51 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
57#ifndef HAVE_MAJOR
58# define major(dev)  (((dev) >> 8) & 0xff)
59# define minor(dev)  ((dev) & 0xff)
60#endif
61#undef HAVE_MAJOR
62
63private int
64bad_link(struct magic_set *ms, int err, char *buf)
65{
66	const char *errfmt;
67	int mime = ms->flags & MAGIC_MIME;
68	if ((mime & MAGIC_MIME_TYPE) &&
69	    file_printf(ms, "application/x-symlink")
70	    == -1)
71		return -1;
72	else if (!mime) {
73		if (err == ELOOP)
74			errfmt = "symbolic link in a loop";
75		else
76			errfmt = "broken symbolic link to `%s'";
77		if (ms->flags & MAGIC_ERROR) {
78			file_error(ms, err, errfmt, buf);
79			return -1;
80		}
81		if (file_printf(ms, errfmt, buf) == -1)
82			return -1;
83	}
84	return 1;
85}
86
87private int
88handle_mime(struct magic_set *ms, int mime, const char *str)
89{
90	if ((mime & MAGIC_MIME_TYPE)) {
91		if (file_printf(ms, "application/%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
102protected int
103file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb)
104{
105	int ret = 0;
106	int mime = ms->flags & MAGIC_MIME;
107#ifdef	S_IFLNK
108	char buf[BUFSIZ+4];
109	int 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	/*
119	 * Fstat is cheaper but fails for files you don't have read perms on.
120	 * On 4.2BSD and similar systems, use lstat() to identify symlinks.
121	 */
122#ifdef	S_IFLNK
123	if ((ms->flags & MAGIC_SYMLINK) == 0)
124		ret = lstat(fn, sb);
125	else
126#endif
127	ret = stat(fn, sb);	/* don't merge into if; see "ret =" above */
128
129	if (ret) {
130		if (ms->flags & MAGIC_ERROR) {
131			file_error(ms, errno, "cannot stat `%s'", fn);
132			return -1;
133		}
134		if (file_printf(ms, "cannot open `%s' (%s)",
135		    fn, strerror(errno)) == -1)
136			return -1;
137		return 1;
138	}
139
140	if (!mime) {
141#ifdef S_ISUID
142		if (sb->st_mode & S_ISUID)
143			if (file_printf(ms, "setuid ") == -1)
144				return -1;
145#endif
146#ifdef S_ISGID
147		if (sb->st_mode & S_ISGID)
148			if (file_printf(ms, "setgid ") == -1)
149				return -1;
150#endif
151#ifdef S_ISVTX
152		if (sb->st_mode & S_ISVTX)
153			if (file_printf(ms, "sticky ") == -1)
154				return -1;
155#endif
156	}
157
158	switch (sb->st_mode & S_IFMT) {
159	case S_IFDIR:
160		if (mime) {
161			if (handle_mime(ms, mime, "x-directory") == -1)
162				return -1;
163		} else if (file_printf(ms, "directory") == -1)
164			return -1;
165		return 1;
166#ifdef S_IFCHR
167	case S_IFCHR:
168		/*
169		 * If -s has been specified, treat character special files
170		 * like ordinary files.  Otherwise, just report that they
171		 * are block special files and go on to the next file.
172		 */
173		if ((ms->flags & MAGIC_DEVICES) != 0)
174			break;
175		if (mime) {
176			if (handle_mime(ms, mime, "x-character-device") == -1)
177				return -1;
178		} else {
179#ifdef HAVE_STAT_ST_RDEV
180# ifdef dv_unit
181			if (file_printf(ms, "character special (%d/%d/%d)",
182			    major(sb->st_rdev), dv_unit(sb->st_rdev),
183					dv_subunit(sb->st_rdev)) == -1)
184				return -1;
185# else
186			if (file_printf(ms, "character special (%ld/%ld)",
187			    (long)major(sb->st_rdev), (long)minor(sb->st_rdev))
188			    == -1)
189				return -1;
190# endif
191#else
192			if (file_printf(ms, "character special") == -1)
193				return -1;
194#endif
195		}
196		return 1;
197#endif
198#ifdef S_IFBLK
199	case S_IFBLK:
200		/*
201		 * If -s has been specified, treat block special files
202		 * like ordinary files.  Otherwise, just report that they
203		 * are block special files and go on to the next file.
204		 */
205		if ((ms->flags & MAGIC_DEVICES) != 0)
206			break;
207		if (mime) {
208			if (handle_mime(ms, mime, "x-block-device") == -1)
209				return -1;
210		} else {
211#ifdef HAVE_STAT_ST_RDEV
212# ifdef dv_unit
213			if (file_printf(ms, "block special (%d/%d/%d)",
214					major(sb->st_rdev), dv_unit(sb->st_rdev),
215					dv_subunit(sb->st_rdev)) == -1)
216				return -1;
217# else
218			if (file_printf(ms, "block special (%ld/%ld)",
219					(long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1)
220				return -1;
221# endif
222#else
223			if (file_printf(ms, "block special") == -1)
224				return -1;
225#endif
226		}
227		return 1;
228#endif
229	/* TODO add code to handle V7 MUX and Blit MUX files */
230#ifdef	S_IFIFO
231	case S_IFIFO:
232		if((ms->flags & MAGIC_DEVICES) != 0)
233			break;
234		if (mime) {
235			if (handle_mime(ms, mime, "x-fifo") == -1)
236				return -1;
237		} else if (file_printf(ms, "fifo (named pipe)") == -1)
238			return -1;
239		return 1;
240#endif
241#ifdef	S_IFDOOR
242	case S_IFDOOR:
243		if (mime) {
244			if (handle_mime(ms, mime, "x-door") == -1)
245				return -1;
246		} else if (file_printf(ms, "door") == -1)
247			return -1;
248		return 1;
249#endif
250#ifdef	S_IFLNK
251	case S_IFLNK:
252		if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
253			if (ms->flags & MAGIC_ERROR) {
254			    file_error(ms, errno, "unreadable symlink `%s'",
255				fn);
256			    return -1;
257			}
258			if (mime) {
259				if (handle_mime(ms, mime, "x-symlink") == -1)
260					return -1;
261			} else if (file_printf(ms,
262			    "unreadable symlink `%s' (%s)", fn,
263			    strerror(errno)) == -1)
264				return -1;
265			return 1;
266		}
267		buf[nch] = '\0';	/* readlink(2) does not do this */
268
269		/* If broken symlink, say so and quit early. */
270		if (*buf == '/') {
271			if (stat(buf, &tstatbuf) < 0)
272				return bad_link(ms, errno, buf);
273		} else {
274			char *tmp;
275			char buf2[BUFSIZ+BUFSIZ+4];
276
277			if ((tmp = strrchr(fn,  '/')) == NULL) {
278				tmp = buf; /* in current directory anyway */
279			} else {
280				if (tmp - fn + 1 > BUFSIZ) {
281					if (ms->flags & MAGIC_ERROR) {
282						file_error(ms, 0,
283						    "path too long: `%s'", buf);
284						return -1;
285					}
286					if (mime) {
287						if (handle_mime(ms, mime,
288						    "x-path-too-long") == -1)
289							return -1;
290					} else if (file_printf(ms,
291					    "path too long: `%s'", fn) == -1)
292						return -1;
293					return 1;
294				}
295				/* take dir part */
296				(void)strlcpy(buf2, fn, sizeof buf2);
297				buf2[tmp - fn + 1] = '\0';
298				/* plus (rel) link */
299				(void)strlcat(buf2, buf, sizeof buf2);
300				tmp = buf2;
301			}
302			if (stat(tmp, &tstatbuf) < 0)
303				return bad_link(ms, errno, buf);
304		}
305
306		/* Otherwise, handle it. */
307		if ((ms->flags & MAGIC_SYMLINK) != 0) {
308			const char *p;
309			ms->flags &= MAGIC_SYMLINK;
310			p = magic_file(ms, buf);
311			ms->flags |= MAGIC_SYMLINK;
312			return p != NULL ? 1 : -1;
313		} else { /* just print what it points to */
314			if (mime) {
315				if (handle_mime(ms, mime, "x-symlink") == -1)
316					return -1;
317			} else if (file_printf(ms, "symbolic link to `%s'",
318			    buf) == -1)
319				return -1;
320		}
321		return 1;
322#endif
323#ifdef	S_IFSOCK
324#ifndef __COHERENT__
325	case S_IFSOCK:
326		if (mime) {
327			if (handle_mime(ms, mime, "x-socket") == -1)
328				return -1;
329		} else if (file_printf(ms, "socket") == -1)
330			return -1;
331		return 1;
332#endif
333#endif
334	case S_IFREG:
335		break;
336	default:
337		file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
338		return -1;
339		/*NOTREACHED*/
340	}
341
342	/*
343	 * regular file, check next possibility
344	 *
345	 * If stat() tells us the file has zero length, report here that
346	 * the file is empty, so we can skip all the work of opening and
347	 * reading the file.
348	 * But if the -s option has been given, we skip this optimization,
349	 * since on some systems, stat() reports zero size for raw disk
350	 * partitions.  (If the block special device really has zero length,
351	 * the fact that it is empty will be detected and reported correctly
352	 * when we read the file.)
353	 */
354	if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
355		if (mime) {
356			if (handle_mime(ms, mime, "x-empty") == -1)
357				return -1;
358		} else if (file_printf(ms, "empty") == -1)
359			return -1;
360		return 1;
361	}
362	return 0;
363}
364