fsmagic.c revision 284193 
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 1.75 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
67private int
68bad_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
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, "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
102protected int
103file_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