fsmagic.c revision 133359 
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 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *    This product includes software developed by Ian F. Darwin and others.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
25 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33/*
34 * fsmagic - magic based on filesystem info - directory, special files, etc.
35 */
36
37#include "file.h"
38#include "magic.h"
39#include <string.h>
40#ifdef HAVE_UNISTD_H
41#include <unistd.h>
42#endif
43#include <stdlib.h>
44#include <sys/stat.h>
45/* Since major is a function on SVR4, we cannot use `ifndef major'.  */
46#ifdef MAJOR_IN_MKDEV
47# include <sys/mkdev.h>
48# define HAVE_MAJOR
49#endif
50#ifdef MAJOR_IN_SYSMACROS
51# include <sys/sysmacros.h>
52# define HAVE_MAJOR
53#endif
54#ifdef major			/* Might be defined in sys/types.h.  */
55# define HAVE_MAJOR
56#endif
57
58#ifndef HAVE_MAJOR
59# define major(dev)  (((dev) >> 8) & 0xff)
60# define minor(dev)  ((dev) & 0xff)
61#endif
62#undef HAVE_MAJOR
63
64#ifndef	lint
65FILE_RCSID("@(#)$Id: fsmagic.c,v 1.43 2003/10/14 19:29:55 christos Exp $")
66#endif	/* lint */
67
68protected int
69file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb)
70{
71	int ret = 0;
72#ifdef	S_IFLNK
73	char buf[BUFSIZ+4];
74	int nch;
75	struct stat tstatbuf;
76#endif
77
78	if (fn == NULL)
79		return 0;
80
81	/*
82	 * Fstat is cheaper but fails for files you don't have read perms on.
83	 * On 4.2BSD and similar systems, use lstat() to identify symlinks.
84	 */
85#ifdef	S_IFLNK
86	if ((ms->flags & MAGIC_SYMLINK) == 0)
87		ret = lstat(fn, sb);
88	else
89#endif
90	ret = stat(fn, sb);	/* don't merge into if; see "ret =" above */
91
92	if (ret) {
93		if (ms->flags & MAGIC_ERROR) {
94			file_error(ms, errno, "cannot stat `%s'", fn);
95			return -1;
96		}
97		if (file_printf(ms, "cannot open (%s)",
98		    fn, strerror(errno)) == -1)
99			return -1;
100		return 1;
101	}
102
103	if ((ms->flags & MAGIC_MIME) != 0) {
104		if ((sb->st_mode & S_IFMT) != S_IFREG) {
105			if (file_printf(ms, "application/x-not-regular-file")
106			    == -1)
107				return -1;
108			return 1;
109		}
110	}
111	else {
112#ifdef S_ISUID
113		if (sb->st_mode & S_ISUID)
114			if (file_printf(ms, "setuid ") == -1)
115				return -1;
116#endif
117#ifdef S_ISGID
118		if (sb->st_mode & S_ISGID)
119			if (file_printf(ms, "setgid ") == -1)
120				return -1;
121#endif
122#ifdef S_ISVTX
123		if (sb->st_mode & S_ISVTX)
124			if (file_printf(ms, "sticky ") == -1)
125				return -1;
126#endif
127	}
128
129	switch (sb->st_mode & S_IFMT) {
130	case S_IFDIR:
131		if (file_printf(ms, "directory") == -1)
132			return -1;
133		return 1;
134#ifdef S_IFCHR
135	case S_IFCHR:
136		/*
137		 * If -s has been specified, treat character special files
138		 * like ordinary files.  Otherwise, just report that they
139		 * are block special files and go on to the next file.
140		 */
141		if ((ms->flags & MAGIC_DEVICES) != 0)
142			break;
143#ifdef HAVE_ST_RDEV
144# ifdef dv_unit
145		if (file_printf(ms, "character special (%d/%d/%d)",
146		    major(sb->st_rdev), dv_unit(sb->st_rdev),
147		    dv_subunit(sb->st_rdev)) == -1)
148			return -1;
149# else
150		if (file_printf(ms, "character special (%ld/%ld)",
151		    (long) major(sb->st_rdev), (long) minor(sb->st_rdev)) == -1)
152			return -1;
153# endif
154#else
155		if (file_printf(ms, "character special") == -1)
156			return -1;
157#endif
158		return 1;
159#endif
160#ifdef S_IFBLK
161	case S_IFBLK:
162		/*
163		 * If -s has been specified, treat block special files
164		 * like ordinary files.  Otherwise, just report that they
165		 * are block special files and go on to the next file.
166		 */
167		if ((ms->flags & MAGIC_DEVICES) != 0)
168			break;
169#ifdef HAVE_ST_RDEV
170# ifdef dv_unit
171		if (file_printf(ms, "block special (%d/%d/%d)",
172		    major(sb->st_rdev), dv_unit(sb->st_rdev),
173		    dv_subunit(sb->st_rdev)) == -1)
174			return -1;
175# else
176		if (file_printf(ms, "block special (%ld/%ld)",
177		    (long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1)
178			return -1;
179# endif
180#else
181		if (file_printf(ms, "block special") == -1)
182			return -1;
183#endif
184		return 1;
185#endif
186	/* TODO add code to handle V7 MUX and Blit MUX files */
187#ifdef	S_IFIFO
188	case S_IFIFO:
189		if (file_printf(ms, "fifo (named pipe)") == -1)
190			return -1;
191		return 1;
192#endif
193#ifdef	S_IFDOOR
194	case S_IFDOOR:
195		if (file_printf(ms, "door") == -1)
196			return -1;
197		return 1;
198#endif
199#ifdef	S_IFLNK
200	case S_IFLNK:
201		if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
202			if (ms->flags & MAGIC_ERROR) {
203			    file_error(ms, errno, "unreadable symlink `%s'",
204				fn);
205			    return -1;
206			}
207			if (file_printf(ms,
208			    "unreadable symlink `%s' (%s)", fn,
209			    strerror(errno)) == -1)
210				return -1;
211			return 1;
212		}
213		buf[nch] = '\0';	/* readlink(2) forgets this */
214
215		/* If broken symlink, say so and quit early. */
216		if (*buf == '/') {
217		    if (stat(buf, &tstatbuf) < 0) {
218			    if (ms->flags & MAGIC_ERROR) {
219				    file_error(ms, errno,
220					"broken symbolic link to `%s'", buf);
221				    return -1;
222			    }
223			    if (file_printf(ms, "broken symbolic link to `%s'",
224				buf) == -1)
225				    return -1;
226			    return 1;
227		    }
228		}
229		else {
230			char *tmp;
231			char buf2[BUFSIZ+BUFSIZ+4];
232
233			if ((tmp = strrchr(fn,  '/')) == NULL) {
234				tmp = buf; /* in current directory anyway */
235			} else {
236				if (tmp - fn + 1 > BUFSIZ) {
237					if (ms->flags & MAGIC_ERROR) {
238						file_error(ms, 0,
239						    "path too long: `%s'", buf);
240						return -1;
241					}
242					if (file_printf(ms,
243					    "path too long: `%s'", fn) == -1)
244						return -1;
245					return 1;
246				}
247				(void)strcpy(buf2, fn);  /* take dir part */
248				buf2[tmp - fn + 1] = '\0';
249				(void)strcat(buf2, buf); /* plus (rel) link */
250				tmp = buf2;
251			}
252			if (stat(tmp, &tstatbuf) < 0) {
253				if (ms->flags & MAGIC_ERROR) {
254					file_error(ms, errno,
255					    "broken symbolic link to `%s'",
256					    buf);
257					return -1;
258				}
259				if (file_printf(ms,
260				    "broken symbolic link to `%s'", buf) == -1)
261					return -1;
262				return 1;
263			}
264		}
265
266		/* Otherwise, handle it. */
267		if ((ms->flags & MAGIC_SYMLINK) != 0) {
268			const char *p;
269			ms->flags &= MAGIC_SYMLINK;
270			p = magic_file(ms, buf);
271			ms->flags |= MAGIC_SYMLINK;
272			return p != NULL ? 1 : -1;
273		} else { /* just print what it points to */
274			if (file_printf(ms, "symbolic link to `%s'",
275			    buf) == -1)
276				return -1;
277		}
278	return 1;
279#endif
280#ifdef	S_IFSOCK
281#ifndef __COHERENT__
282	case S_IFSOCK:
283		if (file_printf(ms, "socket") == -1)
284			return -1;
285		return 1;
286#endif
287#endif
288	case S_IFREG:
289		break;
290	default:
291		file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
292		return -1;
293		/*NOTREACHED*/
294	}
295
296	/*
297	 * regular file, check next possibility
298	 *
299	 * If stat() tells us the file has zero length, report here that
300	 * the file is empty, so we can skip all the work of opening and
301	 * reading the file.
302	 * But if the -s option has been given, we skip this optimization,
303	 * since on some systems, stat() reports zero size for raw disk
304	 * partitions.  (If the block special device really has zero length,
305	 * the fact that it is empty will be detected and reported correctly
306	 * when we read the file.)
307	 */
308	if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
309		if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
310		    "application/x-empty" : "empty") == -1)
311			return -1;
312		return 1;
313	}
314	return 0;
315}
316