xref: /freebsd/usr.bin/xinstall/xinstall.c (revision 952d112864d8008aa87278a30a539d888a8493cd)
1 /*
2  * Copyright (c) 1987, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR 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 #ifndef lint
35 static const char copyright[] =
36 "@(#) Copyright (c) 1987, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 /*static char sccsid[] = "From: @(#)xinstall.c	8.1 (Berkeley) 7/21/93";*/
42 static const char rcsid[] =
43 	"$Id: xinstall.c,v 1.21 1997/02/22 19:57:55 peter Exp $";
44 #endif /* not lint */
45 
46 /*-
47  * Todo:
48  * o for -C, compare original files except in -s case.
49  * o for -C, don't change anything if nothing needs be changed.  In
50  *   particular, don't toggle the immutable flags just to allow null
51  *   attribute changes and don't clear the dump flag.  (I think inode
52  *   ctimes are not updated for null attribute changes, but this is a
53  *   bug.)
54  * o independent of -C, if a copy must be made, then copy to a tmpfile,
55  *   set all attributes except the immutable flags, then rename, then
56  *   set the immutable flags.  It's annoying that the immutable flags
57  *   defeat the atomicicity of rename - it seems that there must be
58  * o a window where the target is not immutable.
59  */
60 
61 #include <sys/param.h>
62 #include <sys/wait.h>
63 #include <sys/mman.h>
64 #include <sys/stat.h>
65 #include <sys/mount.h>
66 
67 #include <ctype.h>
68 #include <err.h>
69 #include <errno.h>
70 #include <fcntl.h>
71 #include <grp.h>
72 #include <paths.h>
73 #include <pwd.h>
74 #include <stdio.h>
75 #include <stdlib.h>
76 #include <string.h>
77 #include <unistd.h>
78 #include <sysexits.h>
79 #include <utime.h>
80 
81 #include "pathnames.h"
82 
83 int debug, docompare, docopy, dodir, dopreserve, dostrip, verbose;
84 int mode = S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
85 char *group, *owner, pathbuf[MAXPATHLEN];
86 char pathbuf2[MAXPATHLEN];
87 
88 #define	DIRECTORY	0x01		/* Tell install it's a directory. */
89 #define	SETFLAGS	0x02		/* Tell install to set flags. */
90 #define	NOCHANGEBITS	(UF_IMMUTABLE | UF_APPEND | SF_IMMUTABLE | SF_APPEND)
91 
92 void	copy __P((int, char *, int, char *, off_t));
93 int	compare __P((int, const char *, int, const char *,
94 		     const struct stat *, const struct stat *));
95 void	install __P((char *, char *, u_long, u_int));
96 void	install_dir __P((char *));
97 u_long	string_to_flags __P((char **, u_long *, u_long *));
98 void	strip __P((char *));
99 void	usage __P((void));
100 int	trymmap __P((int));
101 
102 #define ALLOW_NUMERIC_IDS 1
103 #ifdef ALLOW_NUMERIC_IDS
104 
105 uid_t	uid;
106 gid_t	gid;
107 
108 uid_t	resolve_uid __P((char *));
109 gid_t	resolve_gid __P((char *));
110 u_long	numeric_id __P((char *, char *));
111 
112 #else
113 
114 struct passwd *pp;
115 struct group *gp;
116 
117 #endif /* ALLOW_NUMERIC_IDS */
118 
119 int
120 main(argc, argv)
121 	int argc;
122 	char *argv[];
123 {
124 	struct stat from_sb, to_sb;
125 	mode_t *set;
126 	u_long fset;
127 	u_int iflags;
128 	int ch, no_target;
129 	char *flags, *to_name;
130 
131 	iflags = 0;
132 	while ((ch = getopt(argc, argv, "CcdDf:g:m:o:psv")) != -1)
133 		switch((char)ch) {
134 		case 'C':
135 			docompare = docopy = 1;
136 			break;
137 		case 'c':
138 			docopy = 1;
139 			break;
140 		case 'D':
141 			debug++;
142 			break;
143 		case 'd':
144 			dodir = 1;
145 			break;
146 		case 'f':
147 			flags = optarg;
148 			if (string_to_flags(&flags, &fset, NULL))
149 				errx(EX_USAGE, "%s: invalid flag", flags);
150 			iflags |= SETFLAGS;
151 			break;
152 		case 'g':
153 			group = optarg;
154 			break;
155 		case 'm':
156 			if (!(set = setmode(optarg)))
157 				errx(EX_USAGE, "invalid file mode: %s",
158 				     optarg);
159 			mode = getmode(set, 0);
160 			break;
161 		case 'o':
162 			owner = optarg;
163 			break;
164 		case 'p':
165 			docompare = docopy = dopreserve = 1;
166 			break;
167 		case 's':
168 			dostrip = 1;
169 			break;
170 		case 'v':
171 			verbose = 1;
172 			break;
173 		case '?':
174 		default:
175 			usage();
176 		}
177 	argc -= optind;
178 	argv += optind;
179 
180 	/* some options make no sense when creating directories */
181 	if ((docompare || dostrip) && dodir)
182 		usage();
183 
184 	/* must have at least two arguments, except when creating directories */
185 	if (argc < 2 && !dodir)
186 		usage();
187 
188 #ifdef ALLOW_NUMERIC_IDS
189 
190 	if (owner)
191 		uid = resolve_uid(owner);
192 	if (group)
193 		gid = resolve_gid(group);
194 
195 #else
196 
197 	/* get group and owner id's */
198 	if (owner && !(pp = getpwnam(owner)))
199 		errx(EX_NOUSER, "unknown user %s", owner);
200 	if (group && !(gp = getgrnam(group)))
201 		errx(EX_NOUSER, "unknown group %s", group);
202 
203 #endif /* ALLOW_NUMERIC_IDS */
204 
205 	if (dodir) {
206 		for (; *argv != NULL; ++argv)
207 			install_dir(*argv);
208 		exit(EX_OK);
209 		/* NOTREACHED */
210 	}
211 
212 	no_target = stat(to_name = argv[argc - 1], &to_sb);
213 	if (!no_target && (to_sb.st_mode & S_IFMT) == S_IFDIR) {
214 		for (; *argv != to_name; ++argv)
215 			install(*argv, to_name, fset, iflags | DIRECTORY);
216 		exit(EX_OK);
217 		/* NOTREACHED */
218 	}
219 
220 	/* can't do file1 file2 directory/file */
221 	if (argc != 2)
222 		usage();
223 
224 	if (!no_target) {
225 		if (stat(*argv, &from_sb))
226 			err(EX_OSERR, "%s", *argv);
227 		if (!S_ISREG(to_sb.st_mode)) {
228 			errno = EFTYPE;
229 			err(EX_OSERR, "%s", to_name);
230 		}
231 		if (to_sb.st_dev == from_sb.st_dev &&
232 		    to_sb.st_ino == from_sb.st_ino)
233 			errx(EX_USAGE,
234 			    "%s and %s are the same file", *argv, to_name);
235 /*
236  * XXX - It's not at all clear why this code was here, since it completely
237  * duplicates code install().  The version in install() handles the -C flag
238  * correctly, so we'll just disable this for now.
239  */
240 #if 0
241 		/*
242 		 * Unlink now... avoid ETXTBSY errors later.  Try and turn
243 		 * off the append/immutable bits -- if we fail, go ahead,
244 		 * it might work.
245 		 */
246 		if (to_sb.st_flags & NOCHANGEBITS)
247 			(void)chflags(to_name,
248 			    to_sb.st_flags & ~(NOCHANGEBITS));
249 		(void)unlink(to_name);
250 #endif
251 	}
252 	install(*argv, to_name, fset, iflags);
253 	exit(EX_OK);
254 	/* NOTREACHED */
255 }
256 
257 #ifdef ALLOW_NUMERIC_IDS
258 
259 uid_t
260 resolve_uid(s)
261 	char *s;
262 {
263 	struct passwd *pw;
264 
265 	return ((pw = getpwnam(s)) == NULL) ?
266 		(uid_t) numeric_id(s, "user") : pw->pw_uid;
267 }
268 
269 gid_t
270 resolve_gid(s)
271 	char *s;
272 {
273 	struct group *gr;
274 
275 	return ((gr = getgrnam(s)) == NULL) ?
276 		(gid_t) numeric_id(s, "group") : gr->gr_gid;
277 }
278 
279 u_long
280 numeric_id(name, type)
281 	char *name, *type;
282 {
283 	u_long val;
284 	char *ep;
285 
286 	/*
287 	 * XXX
288 	 * We know that uid_t's and gid_t's are unsigned longs.
289 	 */
290 	errno = 0;
291 	val = strtoul(name, &ep, 10);
292 	if (errno)
293 		err(EX_NOUSER, "%s", name);
294 	if (*ep != '\0')
295 		errx(EX_NOUSER, "unknown %s %s", type, name);
296 	return (val);
297 }
298 
299 #endif /* ALLOW_NUMERIC_IDS */
300 
301 /*
302  * install --
303  *	build a path name and install the file
304  */
305 void
306 install(from_name, to_name, fset, flags)
307 	char *from_name, *to_name;
308 	u_long fset;
309 	u_int flags;
310 {
311 	struct stat from_sb, to_sb;
312 	int devnull, from_fd, to_fd, serrno;
313 	char *p, *old_to_name = 0;
314 
315 	if (debug >= 2 && !docompare)
316 		fprintf(stderr, "install: invoked without -C for %s to %s\n",
317 			from_name, to_name);
318 
319 	/* If try to install NULL file to a directory, fails. */
320 	if (flags & DIRECTORY || strcmp(from_name, _PATH_DEVNULL)) {
321 		if (stat(from_name, &from_sb))
322 			err(EX_OSERR, "%s", from_name);
323 		if (!S_ISREG(from_sb.st_mode)) {
324 			errno = EFTYPE;
325 			err(EX_OSERR, "%s", from_name);
326 		}
327 		/* Build the target path. */
328 		if (flags & DIRECTORY) {
329 			(void)snprintf(pathbuf, sizeof(pathbuf), "%s/%s",
330 			    to_name,
331 			    (p = strrchr(from_name, '/')) ? ++p : from_name);
332 			to_name = pathbuf;
333 		}
334 		devnull = 0;
335 	} else {
336 		from_sb.st_flags = 0;	/* XXX */
337 		devnull = 1;
338 	}
339 
340 	if (docompare) {
341 		old_to_name = to_name;
342 		/*
343 		 * Make a new temporary file in the same file system
344 		 * (actually, in in the same directory) as the target so
345 		 * that the temporary file can be renamed to the target.
346 		 */
347 		snprintf(pathbuf2, sizeof pathbuf2, "%s", to_name);
348 		p = strrchr(pathbuf2, '/');
349 		p = (p == NULL ? pathbuf2 : p + 1);
350 		snprintf(p, &pathbuf2[sizeof pathbuf2] - p, "INS@XXXX");
351 		to_fd = mkstemp(pathbuf2);
352 		if (to_fd < 0)
353 			/* XXX should fall back to not comparing. */
354 			err(EX_OSERR, "mkstemp: %s for %s", pathbuf2, to_name);
355 		to_name = pathbuf2;
356 	} else {
357 		/*
358 		 * Unlink now... avoid errors later.  Try to turn off the
359 		 * append/immutable bits -- if we fail, go ahead, it might
360 		 * work.
361 		 */
362 		if (stat(to_name, &to_sb) == 0 && to_sb.st_flags & NOCHANGEBITS)
363 			(void)chflags(to_name, to_sb.st_flags & ~NOCHANGEBITS);
364 		unlink(to_name);
365 
366 		/* Create target. */
367 		to_fd = open(to_name,
368 			     O_CREAT | O_RDWR | O_TRUNC, S_IRUSR | S_IWUSR);
369 		if (to_fd < 0)
370 			err(EX_OSERR, "%s", to_name);
371 	}
372 
373 	if (!devnull) {
374 		if ((from_fd = open(from_name, O_RDONLY, 0)) < 0) {
375 			serrno = errno;
376 			(void)unlink(to_name);
377 			errno = serrno;
378 			err(EX_OSERR, "%s", from_name);
379 		}
380 		copy(from_fd, from_name, to_fd, to_name, from_sb.st_size);
381 		(void)close(from_fd);
382 	}
383 
384 	if (dostrip)
385 		strip(to_name);
386 
387 	/*
388 	 * Unfortunately, because we strip the installed file and not the
389 	 * original one, it is impossible to do the comparison without
390 	 * first laboriously copying things over and then comparing.
391 	 * It may be possible to better optimize the !dostrip case, however.
392 	 * For further study.
393 	 */
394 	if (docompare) {
395 		struct stat old_sb, new_sb, timestamp_sb;
396 		int old_fd;
397 		struct utimbuf utb;
398 
399 		old_fd = open(old_to_name, O_RDONLY, 0);
400 		if (old_fd < 0 && errno == ENOENT)
401 			goto different;
402 		if (old_fd < 0)
403 			err(EX_OSERR, "%s", old_to_name);
404 		fstat(old_fd, &old_sb);
405 		if (old_sb.st_flags & NOCHANGEBITS)
406 			(void)fchflags(old_fd, old_sb.st_flags & ~NOCHANGEBITS);
407 		fstat(to_fd, &new_sb);
408 		if (compare(old_fd, old_to_name, to_fd, to_name, &old_sb,
409 			    &new_sb)) {
410 different:
411 			if (debug != 0)
412 				fprintf(stderr,
413 					"install: renaming for %s: %s to %s\n",
414 					from_name, to_name, old_to_name);
415 			if (dopreserve && stat(from_name, &timestamp_sb) == 0) {
416 				utb.actime = from_sb.st_atime;
417 				utb.modtime = from_sb.st_mtime;
418 				(void)utime(to_name, &utb);
419 			}
420 moveit:
421 			if (verbose) {
422 				printf("install: %s -> %s\n",
423 					from_name, old_to_name);
424 			}
425 			if (rename(to_name, old_to_name) < 0) {
426 				serrno = errno;
427 				unlink(to_name);
428 				unlink(old_to_name);
429 				errno = serrno;
430 				err(EX_OSERR, "rename: %s to %s", to_name,
431 				    old_to_name);
432 			}
433 			close(old_fd);
434 		} else {
435 			if (old_sb.st_nlink != 1) {
436 				/*
437 				 * Replace the target, although it hasn't
438 				 * changed, to snap the extra links.  But
439 				 * preserve the target file times.
440 				 */
441 				if (fstat(old_fd, &timestamp_sb) == 0) {
442 					utb.actime = timestamp_sb.st_atime;
443 					utb.modtime = timestamp_sb.st_mtime;
444 					(void)utime(to_name, &utb);
445 				}
446 				goto moveit;
447 			}
448 			if (unlink(to_name) < 0)
449 				err(EX_OSERR, "unlink: %s", to_name);
450 			close(to_fd);
451 			to_fd = old_fd;
452 		}
453 		to_name = old_to_name;
454 	}
455 
456 	/*
457 	 * Set owner, group, mode for target; do the chown first,
458 	 * chown may lose the setuid bits.
459 	 */
460 	if ((group || owner) &&
461 #ifdef ALLOW_NUMERIC_IDS
462 	    fchown(to_fd, owner ? uid : -1, group ? gid : -1)) {
463 #else
464 	    fchown(to_fd, owner ? pp->pw_uid : -1, group ? gp->gr_gid : -1)) {
465 #endif
466 		serrno = errno;
467 		(void)unlink(to_name);
468 		errno = serrno;
469 		err(EX_OSERR,"%s: chown/chgrp", to_name);
470 	}
471 	if (fchmod(to_fd, mode)) {
472 		serrno = errno;
473 		(void)unlink(to_name);
474 		errno = serrno;
475 		err(EX_OSERR, "%s: chmod", to_name);
476 	}
477 
478 	/*
479 	 * If provided a set of flags, set them, otherwise, preserve the
480 	 * flags, except for the dump flag.
481 	 */
482 	if (fchflags(to_fd,
483 	    flags & SETFLAGS ? fset : from_sb.st_flags & ~UF_NODUMP)) {
484 		serrno = errno;
485 		(void)unlink(to_name);
486 		errno = serrno;
487 		err(EX_OSERR, "%s: chflags", to_name);
488 	}
489 
490 	(void)close(to_fd);
491 	if (!docopy && !devnull && unlink(from_name))
492 		err(EX_OSERR, "%s", from_name);
493 }
494 
495 /*
496  * compare --
497  *	compare two files; non-zero means files differ
498  */
499 int
500 compare(int from_fd, const char *from_name, int to_fd, const char *to_name,
501 	const struct stat *from_sb, const struct stat *to_sb)
502 {
503 	char *p, *q;
504 	int rv;
505 	size_t tsize;
506 	int done_compare;
507 
508 	if (from_sb->st_size != to_sb->st_size)
509 		return 1;
510 
511 	tsize = (size_t)from_sb->st_size;
512 
513 	if (tsize <= 8 * 1024 * 1024) {
514 		done_compare = 0;
515 		if (trymmap(from_fd) && trymmap(to_fd)) {
516 			p = mmap(NULL, tsize, PROT_READ, MAP_SHARED, from_fd, (off_t)0);
517 			if (p == (char *)MAP_FAILED)
518 				goto out;
519 			q = mmap(NULL, tsize, PROT_READ, MAP_SHARED, to_fd, (off_t)0);
520 			if (q == (char *)MAP_FAILED) {
521 				munmap(p, tsize);
522 				goto out;
523 			}
524 
525 			rv = memcmp(p, q, tsize);
526 			munmap(p, tsize);
527 			munmap(q, tsize);
528 			done_compare = 1;
529 		}
530 	out:
531 		if (!done_compare) {
532 			char buf1[MAXBSIZE];
533 			char buf2[MAXBSIZE];
534 			int n1, n2;
535 
536 			rv = 0;
537 			lseek(from_fd, 0, SEEK_SET);
538 			lseek(to_fd, 0, SEEK_SET);
539 			while (rv == 0) {
540 				n1 = read(from_fd, buf1, sizeof(buf1));
541 				if (n1 == 0)
542 					break;		/* EOF */
543 				else if (n1 > 0) {
544 					n2 = read(to_fd, buf2, n1);
545 					if (n2 == n1)
546 						rv = memcmp(buf1, buf2, n1);
547 					else
548 						rv = 1;	/* out of sync */
549 				} else
550 					rv = 1;		/* read failure */
551 			}
552 			lseek(from_fd, 0, SEEK_SET);
553 			lseek(to_fd, 0, SEEK_SET);
554 		}
555 	} else
556 		rv = 1;	/* don't bother in this case */
557 
558 	return rv;
559 }
560 
561 /*
562  * copy --
563  *	copy from one file to another
564  */
565 void
566 copy(from_fd, from_name, to_fd, to_name, size)
567 	register int from_fd, to_fd;
568 	char *from_name, *to_name;
569 	off_t size;
570 {
571 	register int nr, nw;
572 	int serrno;
573 	char *p, buf[MAXBSIZE];
574 	int done_copy;
575 
576 	/*
577 	 * Mmap and write if less than 8M (the limit is so we don't totally
578 	 * trash memory on big files.  This is really a minor hack, but it
579 	 * wins some CPU back.
580 	 */
581 	done_copy = 0;
582 	if (size <= 8 * 1048576 && trymmap(from_fd)) {
583 		if ((p = mmap(NULL, (size_t)size, PROT_READ,
584 				MAP_SHARED, from_fd, (off_t)0)) == (char *)MAP_FAILED)
585 			goto out;
586 		if ((nw = write(to_fd, p, size)) != size) {
587 			serrno = errno;
588 			(void)unlink(to_name);
589 			errno = nw > 0 ? EIO : serrno;
590 			err(EX_OSERR, "%s", to_name);
591 		}
592 		done_copy = 1;
593 	out:
594 	}
595 	if (!done_copy) {
596 		while ((nr = read(from_fd, buf, sizeof(buf))) > 0)
597 			if ((nw = write(to_fd, buf, nr)) != nr) {
598 				serrno = errno;
599 				(void)unlink(to_name);
600 				errno = nw > 0 ? EIO : serrno;
601 				err(EX_OSERR, "%s", to_name);
602 			}
603 		if (nr != 0) {
604 			serrno = errno;
605 			(void)unlink(to_name);
606 			errno = serrno;
607 			err(EX_OSERR, "%s", from_name);
608 		}
609 	}
610 }
611 
612 /*
613  * strip --
614  *	use strip(1) to strip the target file
615  */
616 void
617 strip(to_name)
618 	char *to_name;
619 {
620 	int serrno, status;
621 
622 	switch (vfork()) {
623 	case -1:
624 		serrno = errno;
625 		(void)unlink(to_name);
626 		errno = serrno;
627 		err(EX_TEMPFAIL, "fork");
628 	case 0:
629 		execlp("strip", "strip", to_name, NULL);
630 		err(EX_OSERR, "exec(strip)");
631 	default:
632 		if (wait(&status) == -1 || status) {
633 			(void)unlink(to_name);
634 			exit(EX_SOFTWARE);
635 			/* NOTREACHED */
636 		}
637 	}
638 }
639 
640 /*
641  * install_dir --
642  *	build directory heirarchy
643  */
644 void
645 install_dir(path)
646         char *path;
647 {
648 	register char *p;
649 	struct stat sb;
650 	int ch;
651 
652 	for (p = path;; ++p)
653 		if (!*p || (p != path && *p  == '/')) {
654 			ch = *p;
655 			*p = '\0';
656 			if (stat(path, &sb)) {
657 				if (errno != ENOENT || mkdir(path, 0777) < 0) {
658 					err(EX_OSERR, "%s", path);
659 					/* NOTREACHED */
660 				}
661 			}
662 			if (!(*p = ch))
663 				break;
664  		}
665 
666 	if (((gid != (gid_t)-1 || uid != (uid_t)-1) && chown(path, uid, gid)) ||
667 	    chmod(path, mode)) {
668 		warn("%s", path);
669 	}
670 }
671 
672 /*
673  * usage --
674  *	print a usage message and die
675  */
676 void
677 usage()
678 {
679 	(void)fprintf(stderr,"\
680 usage: install [-CcDps] [-f flags] [-g group] [-m mode] [-o owner] file1 file2\n\
681        install [-CcDps] [-f flags] [-g group] [-m mode] [-o owner] file1 ...\n\
682              fileN directory\n\
683        install -d [-g group] [-m mode] [-o owner] directory ...\n");
684 	exit(EX_USAGE);
685 	/* NOTREACHED */
686 }
687 
688 /*
689  * trymmap --
690  *	return true (1) if mmap should be tried, false (0) if not.
691  */
692 int
693 trymmap(fd)
694 	int fd;
695 {
696 	struct statfs stfs;
697 
698 	if (fstatfs(fd, &stfs) < 0)
699 		return 0;
700 	switch(stfs.f_type) {
701 	case MOUNT_UFS:		/* should be safe.. */
702 	case MOUNT_CD9660:	/* should be safe.. */
703 		return 1;
704 	}
705 	return 0;
706 }
707