xref: /netbsd-src/bin/pax/ar_io.c (revision 8b0f9554ff8762542c4defc4f70e1eb76fb508fa)
1 /*	$NetBSD: ar_io.c,v 1.48 2007/04/23 18:40:22 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1992 Keith Muller.
5  * Copyright (c) 1992, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * Keith Muller of the University of California, San Diego.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #if HAVE_NBTOOL_CONFIG_H
37 #include "nbtool_config.h"
38 #endif
39 
40 #include <sys/cdefs.h>
41 #if !defined(lint)
42 #if 0
43 static char sccsid[] = "@(#)ar_io.c	8.2 (Berkeley) 4/18/94";
44 #else
45 __RCSID("$NetBSD: ar_io.c,v 1.48 2007/04/23 18:40:22 christos Exp $");
46 #endif
47 #endif /* not lint */
48 
49 #include <sys/types.h>
50 #include <sys/param.h>
51 #include <sys/time.h>
52 #include <sys/stat.h>
53 #include <sys/ioctl.h>
54 #ifdef HAVE_MTIO_H
55 #include <sys/mtio.h>
56 #endif
57 #include <sys/wait.h>
58 #include <signal.h>
59 #include <string.h>
60 #include <fcntl.h>
61 #include <unistd.h>
62 #include <stdio.h>
63 #include <ctype.h>
64 #include <errno.h>
65 #include <stdlib.h>
66 #ifdef SUPPORT_RMT
67 #define __RMTLIB_PRIVATE
68 #include <rmt.h>
69 #endif /* SUPPORT_RMT */
70 #include "pax.h"
71 #include "options.h"
72 #include "extern.h"
73 
74 /*
75  * Routines which deal directly with the archive I/O device/file.
76  */
77 
78 #define DMOD		0666		/* default mode of created archives */
79 #define EXT_MODE	O_RDONLY	/* open mode for list/extract */
80 #define AR_MODE		(O_WRONLY | O_CREAT | O_TRUNC)	/* mode for archive */
81 #define APP_MODE	O_RDWR		/* mode for append */
82 static char STDO[] =	"<STDOUT>";	/* pseudo name for stdout */
83 static char STDN[] =	"<STDIN>";	/* pseudo name for stdin */
84 static char NONE[] =	"<NONE>";	/* pseudo name for none */
85 static int arfd = -1;			/* archive file descriptor */
86 static int artyp = ISREG;		/* archive type: file/FIFO/tape */
87 static int arvol = 1;			/* archive volume number */
88 static int lstrval = -1;		/* return value from last i/o */
89 static int io_ok;			/* i/o worked on volume after resync */
90 static int did_io;			/* did i/o ever occur on volume? */
91 static int done;			/* set via tty termination */
92 static struct stat arsb;		/* stat of archive device at open */
93 static int invld_rec;			/* tape has out of spec record size */
94 static int wr_trail = 1;		/* trailer was rewritten in append */
95 static int can_unlnk = 0;		/* do we unlink null archives?  */
96 const char *arcname;			/* printable name of archive */
97 const char *gzip_program;		/* name of gzip program */
98 static pid_t zpid = -1;			/* pid of child process */
99 time_t starttime;			/* time the run started */
100 int force_one_volume;			/* 1 if we ignore volume changes */
101 
102 #ifdef HAVE_MTIO_H
103 static int get_phys(void);
104 #endif
105 extern sigset_t s_mask;
106 static void ar_start_gzip(int, const char *, int);
107 static const char *timefmt(char *, size_t, off_t, time_t, const char *);
108 static const char *sizefmt(char *, size_t, off_t);
109 
110 #ifdef SUPPORT_RMT
111 #ifdef SYS_NO_RESTART
112 static int rmtread_with_restart(int, void *, int);
113 static int rmtwrite_with_restart(int, void *, int);
114 #else
115 #define rmtread_with_restart(a, b, c) rmtread((a), (b), (c))
116 #define rmtwrite_with_restart(a, b, c) rmtwrite((a), (b), (c))
117 #endif
118 #endif /* SUPPORT_RMT */
119 
120 /*
121  * ar_open()
122  *	Opens the next archive volume. Determines the type of the device and
123  *	sets up block sizes as required by the archive device and the format.
124  *	Note: we may be called with name == NULL on the first open only.
125  * Return:
126  *	-1 on failure, 0 otherwise
127  */
128 
129 int
130 ar_open(const char *name)
131 {
132 #ifdef HAVE_MTIO_H
133 	struct mtget mb;
134 #endif
135 
136 	if (arfd != -1)
137 		(void)close(arfd);
138 	arfd = -1;
139 	can_unlnk = did_io = io_ok = invld_rec = 0;
140 	artyp = ISREG;
141 	flcnt = 0;
142 
143 #ifdef SUPPORT_RMT
144 	if (name && strchr(name, ':') != NULL && !forcelocal) {
145 		artyp = ISRMT;
146 		if ((arfd = rmtopen(name, O_RDWR, DMOD)) == -1) {
147 			syswarn(0, errno, "Failed open on %s", name);
148 			return -1;
149 		}
150 		blksz = rdblksz = 8192;
151 		lstrval = 1;
152 		return 0;
153 	}
154 #endif /* SUPPORT_RMT */
155 
156 	/*
157 	 * open based on overall operation mode
158 	 */
159 	switch (act) {
160 	case LIST:
161 	case EXTRACT:
162 		if (name == NULL) {
163 			arfd = STDIN_FILENO;
164 			arcname = STDN;
165 		} else if ((arfd = open(name, EXT_MODE, DMOD)) < 0)
166 			syswarn(0, errno, "Failed open to read on %s", name);
167 		if (arfd != -1 && gzip_program != NULL)
168 			ar_start_gzip(arfd, gzip_program, 0);
169 		break;
170 	case ARCHIVE:
171 		if (name == NULL) {
172 			arfd = STDOUT_FILENO;
173 			arcname = STDO;
174 		} else if ((arfd = open(name, AR_MODE, DMOD)) < 0)
175 			syswarn(0, errno, "Failed open to write on %s", name);
176 		else
177 			can_unlnk = 1;
178 		if (arfd != -1 && gzip_program != NULL)
179 			ar_start_gzip(arfd, gzip_program, 1);
180 		break;
181 	case APPND:
182 		if (name == NULL) {
183 			arfd = STDOUT_FILENO;
184 			arcname = STDO;
185 		} else if ((arfd = open(name, APP_MODE, DMOD)) < 0)
186 			syswarn(0, errno, "Failed open to read/write on %s",
187 				name);
188 		break;
189 	case COPY:
190 		/*
191 		 * arfd not used in COPY mode
192 		 */
193 		arcname = NONE;
194 		lstrval = 1;
195 		return 0;
196 	}
197 	if (arfd < 0)
198 		return -1;
199 
200 	if (chdname != NULL)
201 		if (dochdir(chdname) == -1)
202 			return -1;
203 	/*
204 	 * set up is based on device type
205 	 */
206 	if (fstat(arfd, &arsb) < 0) {
207 		syswarn(0, errno, "Failed stat on %s", arcname);
208 		(void)close(arfd);
209 		arfd = -1;
210 		can_unlnk = 0;
211 		return -1;
212 	}
213 	if (S_ISDIR(arsb.st_mode)) {
214 		tty_warn(0, "Cannot write an archive on top of a directory %s",
215 		    arcname);
216 		(void)close(arfd);
217 		arfd = -1;
218 		can_unlnk = 0;
219 		return -1;
220 	}
221 
222 	if (S_ISCHR(arsb.st_mode)) {
223 #ifdef HAVE_MTIO_H
224 		artyp = ioctl(arfd, MTIOCGET, &mb) ? ISCHR : ISTAPE;
225 #else
226 		tty_warn(1, "System does not have tape support");
227 		artyp = ISREG;
228 #endif
229 	} else if (S_ISBLK(arsb.st_mode))
230 		artyp = ISBLK;
231 	else if ((lseek(arfd, (off_t)0L, SEEK_CUR) == -1) && (errno == ESPIPE))
232 		artyp = ISPIPE;
233 	else
234 		artyp = ISREG;
235 
236 	/*
237 	 * Special handling for empty files.
238 	 */
239 	if (artyp == ISREG && arsb.st_size == 0) {
240 		switch (act) {
241 		case LIST:
242 		case EXTRACT:
243 			return -1;
244 		case APPND:
245 			act = -ARCHIVE;
246 			return -1;
247 		case ARCHIVE:
248 			break;
249 		}
250 	}
251 
252 	/*
253 	 * make sure we beyond any doubt that we only can unlink regular files
254 	 * we created
255 	 */
256 	if (artyp != ISREG)
257 		can_unlnk = 0;
258 
259 	/*
260 	 * if we are writing, we are done
261 	 */
262 	if (act == ARCHIVE) {
263 		blksz = rdblksz = wrblksz;
264 		lstrval = 1;
265 		return 0;
266 	}
267 
268 	/*
269 	 * set default blksz on read. APPNDs writes rdblksz on the last volume
270 	 * On all new archive volumes, we shift to wrblksz (if the user
271 	 * specified one, otherwize we will continue to use rdblksz). We
272 	 * must set blocksize based on what kind of device the archive is
273 	 * stored.
274 	 */
275 	switch(artyp) {
276 	case ISTAPE:
277 		/*
278 		 * Tape drives come in at least two flavors. Those that support
279 		 * variable sized records and those that have fixed sized
280 		 * records. They must be treated differently. For tape drives
281 		 * that support variable sized records, we must make large
282 		 * reads to make sure we get the entire record, otherwise we
283 		 * will just get the first part of the record (up to size we
284 		 * asked). Tapes with fixed sized records may or may not return
285 		 * multiple records in a single read. We really do not care
286 		 * what the physical record size is UNLESS we are going to
287 		 * append. (We will need the physical block size to rewrite
288 		 * the trailer). Only when we are appending do we go to the
289 		 * effort to figure out the true PHYSICAL record size.
290 		 */
291 		blksz = rdblksz = MAXBLK;
292 		break;
293 	case ISPIPE:
294 	case ISBLK:
295 	case ISCHR:
296 		/*
297 		 * Blocksize is not a major issue with these devices (but must
298 		 * be kept a multiple of 512). If the user specified a write
299 		 * block size, we use that to read. Under append, we must
300 		 * always keep blksz == rdblksz. Otherwise we go ahead and use
301 		 * the device optimal blocksize as (and if) returned by stat
302 		 * and if it is within pax specs.
303 		 */
304 		if ((act == APPND) && wrblksz) {
305 			blksz = rdblksz = wrblksz;
306 			break;
307 		}
308 
309 		if ((arsb.st_blksize > 0) && (arsb.st_blksize < MAXBLK) &&
310 		    ((arsb.st_blksize % BLKMULT) == 0))
311 			rdblksz = arsb.st_blksize;
312 		else
313 			rdblksz = DEVBLK;
314 		/*
315 		 * For performance go for large reads when we can without harm
316 		 */
317 		if ((act == APPND) || (artyp == ISCHR))
318 			blksz = rdblksz;
319 		else
320 			blksz = MAXBLK;
321 		break;
322 	case ISREG:
323 		/*
324 		 * if the user specified wrblksz works, use it. Under appends
325 		 * we must always keep blksz == rdblksz
326 		 */
327 		if ((act == APPND) && wrblksz && ((arsb.st_size%wrblksz)==0)){
328 			blksz = rdblksz = wrblksz;
329 			break;
330 		}
331 		/*
332 		 * See if we can find the blocking factor from the file size
333 		 */
334 		for (rdblksz = MAXBLK; rdblksz > 0; rdblksz -= BLKMULT)
335 			if ((arsb.st_size % rdblksz) == 0)
336 				break;
337 		/*
338 		 * When we cannot find a match, we may have a flawed archive.
339 		 */
340 		if (rdblksz <= 0)
341 			rdblksz = FILEBLK;
342 		/*
343 		 * for performance go for large reads when we can
344 		 */
345 		if (act == APPND)
346 			blksz = rdblksz;
347 		else
348 			blksz = MAXBLK;
349 		break;
350 	default:
351 		/*
352 		 * should never happen, worst case, slow...
353 		 */
354 		blksz = rdblksz = BLKMULT;
355 		break;
356 	}
357 	lstrval = 1;
358 	return 0;
359 }
360 
361 /*
362  * ar_close()
363  *	closes archive device, increments volume number, and prints i/o summary
364  */
365 void
366 ar_close(void)
367 {
368 	int status;
369 
370 	if (arfd < 0) {
371 		did_io = io_ok = flcnt = 0;
372 		return;
373 	}
374 
375 
376 	/*
377 	 * Close archive file. This may take a LONG while on tapes (we may be
378 	 * forced to wait for the rewind to complete) so tell the user what is
379 	 * going on (this avoids the user hitting control-c thinking pax is
380 	 * broken).
381 	 */
382 	if ((vflag || Vflag) && (artyp == ISTAPE)) {
383 		if (vfpart)
384 			(void)putc('\n', listf);
385 		(void)fprintf(listf,
386 			"%s: Waiting for tape drive close to complete...",
387 			argv0);
388 		(void)fflush(listf);
389 	}
390 
391 	/*
392 	 * if nothing was written to the archive (and we created it), we remove
393 	 * it
394 	 */
395 	if (can_unlnk && (fstat(arfd, &arsb) == 0) && (S_ISREG(arsb.st_mode)) &&
396 	    (arsb.st_size == 0)) {
397 		(void)unlink(arcname);
398 		can_unlnk = 0;
399 	}
400 
401 	/*
402 	 * for a quick extract/list, pax frequently exits before the child
403 	 * process is done
404 	 */
405 	if ((act == LIST || act == EXTRACT) && nflag && zpid > 0)
406 		kill(zpid, SIGINT);
407 
408 #ifdef SUPPORT_RMT
409 	if (artyp == ISRMT)
410 		(void)rmtclose(arfd);
411 	else
412 #endif /* SUPPORT_RMT */
413 		(void)close(arfd);
414 
415 	/* Do not exit before child to ensure data integrity */
416 	if (zpid > 0)
417 		waitpid(zpid, &status, 0);
418 
419 	if ((vflag || Vflag) && (artyp == ISTAPE)) {
420 		(void)fputs("done.\n", listf);
421 		vfpart = 0;
422 		(void)fflush(listf);
423 	}
424 	arfd = -1;
425 
426 	if (!io_ok && !did_io) {
427 		flcnt = 0;
428 		return;
429 	}
430 	did_io = io_ok = 0;
431 
432 	/*
433 	 * The volume number is only increased when the last device has data
434 	 * and we have already determined the archive format.
435 	 */
436 	if (frmt != NULL)
437 		++arvol;
438 
439 	if (!vflag && !Vflag) {
440 		flcnt = 0;
441 		return;
442 	}
443 
444 	/*
445 	 * Print out a summary of I/O for this archive volume.
446 	 */
447 	if (vfpart) {
448 		(void)putc('\n', listf);
449 		vfpart = 0;
450 	}
451 
452 	/* mimic cpio's block count first */
453 	if (frmt && strcmp(NM_CPIO, argv0) == 0) {
454 		(void)fprintf(listf, OFFT_F " blocks\n",
455 		    (rdcnt ? rdcnt : wrcnt) / 5120);
456 	}
457 
458 	ar_summary(0);
459 
460 	(void)fflush(listf);
461 	flcnt = 0;
462 }
463 
464 /*
465  * ar_drain()
466  *	drain any archive format independent padding from an archive read
467  *	from a socket or a pipe. This is to prevent the process on the
468  *	other side of the pipe from getting a SIGPIPE (pax will stop
469  *	reading an archive once a format dependent trailer is detected).
470  */
471 void
472 ar_drain(void)
473 {
474 	int res;
475 	char drbuf[MAXBLK];
476 
477 	/*
478 	 * we only drain from a pipe/socket. Other devices can be closed
479 	 * without reading up to end of file. We sure hope that pipe is closed
480 	 * on the other side so we will get an EOF.
481 	 */
482 	if ((artyp != ISPIPE) || (lstrval <= 0))
483 		return;
484 
485 	/*
486 	 * keep reading until pipe is drained
487 	 */
488 #ifdef SUPPORT_RMT
489 	if (artyp == ISRMT) {
490 		while ((res = rmtread_with_restart(arfd,
491 						   drbuf, sizeof(drbuf))) > 0)
492 			continue;
493 	} else {
494 #endif /* SUPPORT_RMT */
495 		while ((res = read_with_restart(arfd,
496 						drbuf, sizeof(drbuf))) > 0)
497 			continue;
498 #ifdef SUPPORT_RMT
499 	}
500 #endif /* SUPPORT_RMT */
501 	lstrval = res;
502 }
503 
504 /*
505  * ar_set_wr()
506  *	Set up device right before switching from read to write in an append.
507  *	device dependent code (if required) to do this should be added here.
508  *	For all archive devices we are already positioned at the place we want
509  *	to start writing when this routine is called.
510  * Return:
511  *	0 if all ready to write, -1 otherwise
512  */
513 
514 int
515 ar_set_wr(void)
516 {
517 	off_t cpos;
518 
519 	/*
520 	 * we must make sure the trailer is rewritten on append, ar_next()
521 	 * will stop us if the archive containing the trailer was not written
522 	 */
523 	wr_trail = 0;
524 
525 	/*
526 	 * Add any device dependent code as required here
527 	 */
528 	if (artyp != ISREG)
529 		return 0;
530 	/*
531 	 * Ok we have an archive in a regular file. If we were rewriting a
532 	 * file, we must get rid of all the stuff after the current offset
533 	 * (it was not written by pax).
534 	 */
535 	if (((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0) ||
536 	    (ftruncate(arfd, cpos) < 0)) {
537 		syswarn(1, errno, "Unable to truncate archive file");
538 		return -1;
539 	}
540 	return 0;
541 }
542 
543 /*
544  * ar_app_ok()
545  *	check if the last volume in the archive allows appends. We cannot check
546  *	this until we are ready to write since there is no spec that says all
547  *	volumes in a single archive have to be of the same type...
548  * Return:
549  *	0 if we can append, -1 otherwise.
550  */
551 
552 int
553 ar_app_ok(void)
554 {
555 	if (artyp == ISPIPE) {
556 		tty_warn(1,
557 		    "Cannot append to an archive obtained from a pipe.");
558 		return -1;
559 	}
560 
561 	if (!invld_rec)
562 		return 0;
563 	tty_warn(1,
564 	    "Cannot append, device record size %d does not support %s spec",
565 	    rdblksz, argv0);
566 	return -1;
567 }
568 
569 #ifdef SYS_NO_RESTART
570 /*
571  * read_with_restart()
572  *	Equivalent to read() but does retry on signals.
573  *	This function is not needed on 4.2BSD and later.
574  * Return:
575  *	Number of bytes written.  -1 indicates an error.
576  */
577 
578 int
579 read_with_restart(int fd, void *buf, int bsz)
580 {
581 	int r;
582 
583 	while (((r = read(fd, buf, bsz)) < 0) && errno == EINTR)
584 		continue;
585 
586 	return r;
587 }
588 
589 /*
590  * rmtread_with_restart()
591  *	Equivalent to rmtread() but does retry on signals.
592  *	This function is not needed on 4.2BSD and later.
593  * Return:
594  *	Number of bytes written.  -1 indicates an error.
595  */
596 static int
597 rmtread_with_restart(int fd, void *buf, int bsz)
598 {
599 	int r;
600 
601 	while (((r = rmtread(fd, buf, bsz)) < 0) && errno == EINTR)
602 		continue;
603 
604 	return r;
605 }
606 #endif
607 
608 /*
609  * xread()
610  *	Equivalent to read() but does retry on partial read, which may occur
611  *	on signals.
612  * Return:
613  *	Number of bytes read.  0 for end of file, -1 for an error.
614  */
615 
616 int
617 xread(int fd, void *buf, int bsz)
618 {
619 	char *b = buf;
620 	int nread = 0;
621 	int r;
622 
623 	do {
624 #ifdef SUPPORT_RMT
625 		if ((r = rmtread_with_restart(fd, b, bsz)) <= 0)
626 			break;
627 #else
628 		if ((r = read_with_restart(fd, b, bsz)) <= 0)
629 			break;
630 #endif /* SUPPORT_RMT */
631 		b += r;
632 		bsz -= r;
633 		nread += r;
634 	} while (bsz > 0);
635 
636 	return nread ? nread : r;
637 }
638 
639 #ifdef SYS_NO_RESTART
640 /*
641  * write_with_restart()
642  *	Equivalent to write() but does retry on signals.
643  *	This function is not needed on 4.2BSD and later.
644  * Return:
645  *	Number of bytes written.  -1 indicates an error.
646  */
647 
648 int
649 write_with_restart(int fd, void *buf, int bsz)
650 {
651 	int r;
652 
653 	while (((r = write(fd, buf, bsz)) < 0) && errno == EINTR)
654 		;
655 
656 	return r;
657 }
658 
659 /*
660  * rmtwrite_with_restart()
661  *	Equivalent to write() but does retry on signals.
662  *	This function is not needed on 4.2BSD and later.
663  * Return:
664  *	Number of bytes written.  -1 indicates an error.
665  */
666 
667 static int
668 rmtwrite_with_restart(int fd, void *buf, int bsz)
669 {
670 	int r;
671 
672 	while (((r = rmtwrite(fd, buf, bsz)) < 0) && errno == EINTR)
673 		;
674 
675 	return r;
676 }
677 #endif
678 
679 /*
680  * xwrite()
681  *	Equivalent to write() but does retry on partial write, which may occur
682  *	on signals.
683  * Return:
684  *	Number of bytes written.  -1 indicates an error.
685  */
686 
687 int
688 xwrite(int fd, void *buf, int bsz)
689 {
690 	char *b = buf;
691 	int written = 0;
692 	int r;
693 
694 	do {
695 #ifdef SUPPORT_RMT
696 		if ((r = rmtwrite_with_restart(fd, b, bsz)) <= 0)
697 			break;
698 #else
699 		if ((r = write_with_restart(fd, b, bsz)) <= 0)
700 			break;
701 #endif /* SUPPORT_RMT */
702 		b += r;
703 		bsz -= r;
704 		written += r;
705 	} while (bsz > 0);
706 
707 	return written ? written : r;
708 }
709 
710 /*
711  * ar_read()
712  *	read up to a specified number of bytes from the archive into the
713  *	supplied buffer. When dealing with tapes we may not always be able to
714  *	read what we want.
715  * Return:
716  *	Number of bytes in buffer. 0 for end of file, -1 for a read error.
717  */
718 
719 int
720 ar_read(char *buf, int cnt)
721 {
722 	int res = 0;
723 
724 	/*
725 	 * if last i/o was in error, no more reads until reset or new volume
726 	 */
727 	if (lstrval <= 0)
728 		return lstrval;
729 
730 	/*
731 	 * how we read must be based on device type
732 	 */
733 	switch (artyp) {
734 #ifdef SUPPORT_RMT
735 	case ISRMT:
736 		if ((res = rmtread_with_restart(arfd, buf, cnt)) > 0) {
737 			io_ok = 1;
738 			return res;
739 		}
740 		break;
741 #endif /* SUPPORT_RMT */
742 	case ISTAPE:
743 		if ((res = read_with_restart(arfd, buf, cnt)) > 0) {
744 			/*
745 			 * CAUTION: tape systems may not always return the same
746 			 * sized records so we leave blksz == MAXBLK. The
747 			 * physical record size that a tape drive supports is
748 			 * very hard to determine in a uniform and portable
749 			 * manner.
750 			 */
751 			io_ok = 1;
752 			if (res != rdblksz) {
753 				/*
754 				 * Record size changed. If this happens on
755 				 * any record after the first, we probably have
756 				 * a tape drive which has a fixed record size
757 				 * (we are getting multiple records in a single
758 				 * read). Watch out for record blocking that
759 				 * violates pax spec (must be a multiple of
760 				 * BLKMULT).
761 				 */
762 				rdblksz = res;
763 				if (rdblksz % BLKMULT)
764 					invld_rec = 1;
765 			}
766 			return res;
767 		}
768 		break;
769 	case ISREG:
770 	case ISBLK:
771 	case ISCHR:
772 	case ISPIPE:
773 	default:
774 		/*
775 		 * Files are so easy to deal with. These other things cannot
776 		 * be trusted at all. So when we are dealing with character
777 		 * devices and pipes we just take what they have ready for us
778 		 * and return. Trying to do anything else with them runs the
779 		 * risk of failure.
780 		 */
781 		if ((res = read_with_restart(arfd, buf, cnt)) > 0) {
782 			io_ok = 1;
783 			return res;
784 		}
785 		break;
786 	}
787 
788 	/*
789 	 * We are in trouble at this point, something is broken...
790 	 */
791 	lstrval = res;
792 	if (res < 0)
793 		syswarn(1, errno, "Failed read on archive volume %d", arvol);
794 	else
795 		tty_warn(0, "End of archive volume %d reached", arvol);
796 	return res;
797 }
798 
799 /*
800  * ar_write()
801  *	Write a specified number of bytes in supplied buffer to the archive
802  *	device so it appears as a single "block". Deals with errors and tries
803  *	to recover when faced with short writes.
804  * Return:
805  *	Number of bytes written. 0 indicates end of volume reached and with no
806  *	flaws (as best that can be detected). A -1 indicates an unrecoverable
807  *	error in the archive occurred.
808  */
809 
810 int
811 ar_write(char *buf, int bsz)
812 {
813 	int res;
814 	off_t cpos;
815 
816 	/*
817 	 * do not allow pax to create a "bad" archive. Once a write fails on
818 	 * an archive volume prevent further writes to it.
819 	 */
820 	if (lstrval <= 0)
821 		return lstrval;
822 
823 	if ((res = xwrite(arfd, buf, bsz)) == bsz) {
824 		wr_trail = 1;
825 		io_ok = 1;
826 		return bsz;
827 	}
828 	/*
829 	 * write broke, see what we can do with it. We try to send any partial
830 	 * writes that may violate pax spec to the next archive volume.
831 	 */
832 	if (res < 0)
833 		lstrval = res;
834 	else
835 		lstrval = 0;
836 
837 	switch (artyp) {
838 	case ISREG:
839 		if ((res > 0) && (res % BLKMULT)) {
840 			/*
841 			 * try to fix up partial writes which are not BLKMULT
842 			 * in size by forcing the runt record to next archive
843 			 * volume
844 			 */
845 			if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0)
846 				break;
847 			cpos -= (off_t)res;
848 			if (ftruncate(arfd, cpos) < 0)
849 				break;
850 			res = lstrval = 0;
851 			break;
852 		}
853 		if (res >= 0)
854 			break;
855 		/*
856 		 * if file is out of space, handle it like a return of 0
857 		 */
858 		if ((errno == ENOSPC) || (errno == EFBIG))
859 			res = lstrval = 0;
860 #ifdef EDQUOT
861 		if (errno == EDQUOT)
862 			res = lstrval = 0;
863 #endif
864 		break;
865 	case ISTAPE:
866 	case ISCHR:
867 	case ISBLK:
868 #ifdef SUPPORT_RMT
869 	case ISRMT:
870 #endif /* SUPPORT_RMT */
871 		if (res >= 0)
872 			break;
873 		if (errno == EACCES) {
874 			tty_warn(0,
875 			    "Write failed, archive is write protected.");
876 			res = lstrval = 0;
877 			return 0;
878 		}
879 		/*
880 		 * see if we reached the end of media, if so force a change to
881 		 * the next volume
882 		 */
883 		if ((errno == ENOSPC) || (errno == EIO) || (errno == ENXIO))
884 			res = lstrval = 0;
885 		break;
886 	case ISPIPE:
887 	default:
888 		/*
889 		 * we cannot fix errors to these devices
890 		 */
891 		break;
892 	}
893 
894 	/*
895 	 * Better tell the user the bad news...
896 	 * if this is a block aligned archive format, we may have a bad archive
897 	 * if the format wants the header to start at a BLKMULT boundary. While
898 	 * we can deal with the mis-aligned data, it violates spec and other
899 	 * archive readers will likely fail. if the format is not block
900 	 * aligned, the user may be lucky (and the archive is ok).
901 	 */
902 	if (res >= 0) {
903 		if (res > 0)
904 			wr_trail = 1;
905 		io_ok = 1;
906 	}
907 
908 	/*
909 	 * If we were trying to rewrite the trailer and it didn't work, we
910 	 * must quit right away.
911 	 */
912 	if (!wr_trail && (res <= 0)) {
913 		tty_warn(1,
914 		    "Unable to append, trailer re-write failed. Quitting.");
915 		return res;
916 	}
917 
918 	if (res == 0)
919 		tty_warn(0, "End of archive volume %d reached", arvol);
920 	else if (res < 0)
921 		syswarn(1, errno, "Failed write to archive volume: %d", arvol);
922 	else if (!frmt->blkalgn || ((res % frmt->blkalgn) == 0))
923 		tty_warn(0,
924 		    "WARNING: partial archive write. Archive MAY BE FLAWED");
925 	else
926 		tty_warn(1,"WARNING: partial archive write. Archive IS FLAWED");
927 	return res;
928 }
929 
930 /*
931  * ar_rdsync()
932  *	Try to move past a bad spot on a flawed archive as needed to continue
933  *	I/O. Clears error flags to allow I/O to continue.
934  * Return:
935  *	0 when ok to try i/o again, -1 otherwise.
936  */
937 
938 int
939 ar_rdsync(void)
940 {
941 	long fsbz;
942 	off_t cpos;
943 	off_t mpos;
944 #ifdef HAVE_MTIO_H
945 	struct mtop mb;
946 #endif
947 
948 	/*
949 	 * Fail resync attempts at user request (done) or if this is going to be
950 	 * an update/append to a existing archive. if last i/o hit media end,
951 	 * we need to go to the next volume not try a resync
952 	 */
953 	if ((done > 0) || (lstrval == 0))
954 		return -1;
955 
956 	if ((act == APPND) || (act == ARCHIVE)) {
957 		tty_warn(1, "Cannot allow updates to an archive with flaws.");
958 		return -1;
959 	}
960 	if (io_ok)
961 		did_io = 1;
962 
963 	switch(artyp) {
964 #ifdef SUPPORT_RMT
965 	case ISRMT:
966 #endif /* SUPPORT_RMT */
967 	case ISTAPE:
968 #ifdef HAVE_MTIO_H
969 		/*
970 		 * if the last i/o was a successful data transfer, we assume
971 		 * the fault is just a bad record on the tape that we are now
972 		 * past. If we did not get any data since the last resync try
973 		 * to move the tape forward one PHYSICAL record past any
974 		 * damaged tape section. Some tape drives are stubborn and need
975 		 * to be pushed.
976 		 */
977 		if (io_ok) {
978 			io_ok = 0;
979 			lstrval = 1;
980 			break;
981 		}
982 		mb.mt_op = MTFSR;
983 		mb.mt_count = 1;
984 #ifdef SUPPORT_RMT
985 		if (artyp == ISRMT) {
986 			if (rmtioctl(arfd, MTIOCTOP, &mb) < 0)
987 				break;
988 		} else {
989 #endif /* SUPPORT_RMT */
990 			if (ioctl(arfd, MTIOCTOP, &mb) < 0)
991 				break;
992 #ifdef SUPPORT_RMT
993 		}
994 #endif /* SUPPORT_RMT */
995 		lstrval = 1;
996 #else
997 		tty_warn(1, "System does not have tape support");
998 #endif
999 		break;
1000 	case ISREG:
1001 	case ISCHR:
1002 	case ISBLK:
1003 		/*
1004 		 * try to step over the bad part of the device.
1005 		 */
1006 		io_ok = 0;
1007 		if (((fsbz = arsb.st_blksize) <= 0) || (artyp != ISREG))
1008 			fsbz = BLKMULT;
1009 		if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0)
1010 			break;
1011 		mpos = fsbz - (cpos % (off_t)fsbz);
1012 		if (lseek(arfd, mpos, SEEK_CUR) < 0)
1013 			break;
1014 		lstrval = 1;
1015 		break;
1016 	case ISPIPE:
1017 	default:
1018 		/*
1019 		 * cannot recover on these archive device types
1020 		 */
1021 		io_ok = 0;
1022 		break;
1023 	}
1024 	if (lstrval <= 0) {
1025 		tty_warn(1, "Unable to recover from an archive read failure.");
1026 		return -1;
1027 	}
1028 	tty_warn(0, "Attempting to recover from an archive read failure.");
1029 	return 0;
1030 }
1031 
1032 /*
1033  * ar_fow()
1034  *	Move the I/O position within the archive forward the specified number of
1035  *	bytes as supported by the device. If we cannot move the requested
1036  *	number of bytes, return the actual number of bytes moved in skipped.
1037  * Return:
1038  *	0 if moved the requested distance, -1 on complete failure, 1 on
1039  *	partial move (the amount moved is in skipped)
1040  */
1041 
1042 int
1043 ar_fow(off_t sksz, off_t *skipped)
1044 {
1045 	off_t cpos;
1046 	off_t mpos;
1047 
1048 	*skipped = 0;
1049 	if (sksz <= 0)
1050 		return 0;
1051 
1052 	/*
1053 	 * we cannot move forward at EOF or error
1054 	 */
1055 	if (lstrval <= 0)
1056 		return lstrval;
1057 
1058 	/*
1059 	 * Safer to read forward on devices where it is hard to find the end of
1060 	 * the media without reading to it. With tapes we cannot be sure of the
1061 	 * number of physical blocks to skip (we do not know physical block
1062 	 * size at this point), so we must only read forward on tapes!
1063 	 */
1064 	if (artyp == ISTAPE || artyp == ISPIPE
1065 #ifdef SUPPORT_RMT
1066 	    || artyp == ISRMT
1067 #endif /* SUPPORT_RMT */
1068 	    )
1069 		return 0;
1070 
1071 	/*
1072 	 * figure out where we are in the archive
1073 	 */
1074 	if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) >= 0) {
1075 		/*
1076 		 * we can be asked to move farther than there are bytes in this
1077 		 * volume, if so, just go to file end and let normal buf_fill()
1078 		 * deal with the end of file (it will go to next volume by
1079 		 * itself)
1080 		 */
1081 		mpos = cpos + sksz;
1082 		if (artyp == ISREG && mpos > arsb.st_size)
1083 			mpos = arsb.st_size;
1084 		if ((mpos = lseek(arfd, mpos, SEEK_SET)) >= 0) {
1085 			*skipped = mpos - cpos;
1086 			return 0;
1087 		}
1088 	} else {
1089 		if (artyp != ISREG)
1090 			return 0;		/* non-seekable device */
1091 	}
1092 	syswarn(1, errno, "Forward positioning operation on archive failed");
1093 	lstrval = -1;
1094 	return -1;
1095 }
1096 
1097 /*
1098  * ar_rev()
1099  *	move the i/o position within the archive backwards the specified byte
1100  *	count as supported by the device. With tapes drives we RESET rdblksz to
1101  *	the PHYSICAL blocksize.
1102  *	NOTE: We should only be called to move backwards so we can rewrite the
1103  *	last records (the trailer) of an archive (APPEND).
1104  * Return:
1105  *	0 if moved the requested distance, -1 on complete failure
1106  */
1107 
1108 int
1109 ar_rev(off_t sksz)
1110 {
1111 	off_t cpos;
1112 #ifdef HAVE_MTIO_H
1113 	int phyblk;
1114 	struct mtop mb;
1115 #endif
1116 
1117 	/*
1118 	 * make sure we do not have try to reverse on a flawed archive
1119 	 */
1120 	if (lstrval < 0)
1121 		return lstrval;
1122 
1123 	switch(artyp) {
1124 	case ISPIPE:
1125 		if (sksz <= 0)
1126 			break;
1127 		/*
1128 		 * cannot go backwards on these critters
1129 		 */
1130 		tty_warn(1, "Reverse positioning on pipes is not supported.");
1131 		lstrval = -1;
1132 		return -1;
1133 	case ISREG:
1134 	case ISBLK:
1135 	case ISCHR:
1136 	default:
1137 		if (sksz <= 0)
1138 			break;
1139 
1140 		/*
1141 		 * For things other than files, backwards movement has a very
1142 		 * high probability of failure as we really do not know the
1143 		 * true attributes of the device we are talking to (the device
1144 		 * may not even have the ability to lseek() in any direction).
1145 		 * First we figure out where we are in the archive.
1146 		 */
1147 		if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0) {
1148 			syswarn(1, errno,
1149 			   "Unable to obtain current archive byte offset");
1150 			lstrval = -1;
1151 			return -1;
1152 		}
1153 
1154 		/*
1155 		 * we may try to go backwards past the start when the archive
1156 		 * is only a single record. If this happens and we are on a
1157 		 * multi-volume archive, we need to go to the end of the
1158 		 * previous volume and continue our movement backwards from
1159 		 * there.
1160 		 */
1161 		if ((cpos -= sksz) < (off_t)0L) {
1162 			if (arvol > 1) {
1163 				/*
1164 				 * this should never happen
1165 				 */
1166 				tty_warn(1,
1167 				    "Reverse position on previous volume.");
1168 				lstrval = -1;
1169 				return -1;
1170 			}
1171 			cpos = (off_t)0L;
1172 		}
1173 		if (lseek(arfd, cpos, SEEK_SET) < 0) {
1174 			syswarn(1, errno, "Unable to seek archive backwards");
1175 			lstrval = -1;
1176 			return -1;
1177 		}
1178 		break;
1179 	case ISTAPE:
1180 #ifdef SUPPORT_RMT
1181 	case ISRMT:
1182 #endif /* SUPPORT_RMT */
1183 #ifdef HAVE_MTIO_H
1184 		/*
1185 		 * Calculate and move the proper number of PHYSICAL tape
1186 		 * blocks. If the sksz is not an even multiple of the physical
1187 		 * tape size, we cannot do the move (this should never happen).
1188 		 * (We also cannot handle trailers spread over two vols).
1189 		 * get_phys() also makes sure we are in front of the filemark.
1190 		 */
1191 		if ((phyblk = get_phys()) <= 0) {
1192 			lstrval = -1;
1193 			return -1;
1194 		}
1195 
1196 		/*
1197 		 * make sure future tape reads only go by physical tape block
1198 		 * size (set rdblksz to the real size).
1199 		 */
1200 		rdblksz = phyblk;
1201 
1202 		/*
1203 		 * if no movement is required, just return (we must be after
1204 		 * get_phys() so the physical blocksize is properly set)
1205 		 */
1206 		if (sksz <= 0)
1207 			break;
1208 
1209 		/*
1210 		 * ok we have to move. Make sure the tape drive can do it.
1211 		 */
1212 		if (sksz % phyblk) {
1213 			tty_warn(1,
1214 			    "Tape drive unable to backspace requested amount");
1215 			lstrval = -1;
1216 			return -1;
1217 		}
1218 
1219 		/*
1220 		 * move backwards the requested number of bytes
1221 		 */
1222 		mb.mt_op = MTBSR;
1223 		mb.mt_count = sksz/phyblk;
1224 		if (
1225 #ifdef SUPPORT_RMT
1226 		    rmtioctl(arfd, MTIOCTOP, &mb)
1227 #else
1228 		    ioctl(arfd, MTIOCTOP, &mb)
1229 #endif /* SUPPORT_RMT */
1230 		    < 0) {
1231 			syswarn(1, errno, "Unable to backspace tape %ld blocks.",
1232 			    (long) mb.mt_count);
1233 			lstrval = -1;
1234 			return -1;
1235 		}
1236 #else
1237 		tty_warn(1, "System does not have tape support");
1238 #endif
1239 		break;
1240 	}
1241 	lstrval = 1;
1242 	return 0;
1243 }
1244 
1245 #ifdef HAVE_MTIO_H
1246 /*
1247  * get_phys()
1248  *	Determine the physical block size on a tape drive. We need the physical
1249  *	block size so we know how many bytes we skip over when we move with
1250  *	mtio commands. We also make sure we are BEFORE THE TAPE FILEMARK when
1251  *	return.
1252  *	This is one really SLOW routine...
1253  * Return:
1254  *	physical block size if ok (ok > 0), -1 otherwise
1255  */
1256 
1257 static int
1258 get_phys(void)
1259 {
1260 	int padsz = 0;
1261 	int res;
1262 	int phyblk;
1263 	struct mtop mb;
1264 	char scbuf[MAXBLK];
1265 
1266 	/*
1267 	 * move to the file mark, and then back up one record and read it.
1268 	 * this should tell us the physical record size the tape is using.
1269 	 */
1270 	if (lstrval == 1) {
1271 		/*
1272 		 * we know we are at file mark when we get back a 0 from
1273 		 * read()
1274 		 */
1275 #ifdef SUPPORT_RMT
1276 		while ((res = rmtread_with_restart(arfd,
1277 						   scbuf, sizeof(scbuf))) > 0)
1278 #else
1279 		while ((res = read_with_restart(arfd,
1280 						scbuf, sizeof(scbuf))) > 0)
1281 #endif /* SUPPORT_RMT */
1282 			padsz += res;
1283 		if (res < 0) {
1284 			syswarn(1, errno, "Unable to locate tape filemark.");
1285 			return -1;
1286 		}
1287 	}
1288 
1289 	/*
1290 	 * move backwards over the file mark so we are at the end of the
1291 	 * last record.
1292 	 */
1293 	mb.mt_op = MTBSF;
1294 	mb.mt_count = 1;
1295 	if (
1296 #ifdef SUPPORT_RMT
1297 	    rmtioctl(arfd, MTIOCTOP, &mb)
1298 #else
1299 	    ioctl(arfd, MTIOCTOP, &mb)
1300 #endif /* SUPPORT_RMT */
1301 	    < 0) {
1302 		syswarn(1, errno, "Unable to backspace over tape filemark.");
1303 		return -1;
1304 	}
1305 
1306 	/*
1307 	 * move backwards so we are in front of the last record and read it to
1308 	 * get physical tape blocksize.
1309 	 */
1310 	mb.mt_op = MTBSR;
1311 	mb.mt_count = 1;
1312 	if (
1313 #ifdef SUPPORT_RMT
1314 	    rmtioctl(arfd, MTIOCTOP, &mb)
1315 #else
1316 	    ioctl(arfd, MTIOCTOP, &mb)
1317 #endif /* SUPPORT_RMT */
1318 	    < 0) {
1319 		syswarn(1, errno, "Unable to backspace over last tape block.");
1320 		return -1;
1321 	}
1322 	if ((phyblk =
1323 #ifdef SUPPORT_RMT
1324 	     rmtread_with_restart(arfd, scbuf, sizeof(scbuf))
1325 #else
1326 	     read_with_restart(arfd, scbuf, sizeof(scbuf))
1327 #endif /* SUPPORT_RMT */
1328 	    ) <= 0) {
1329 		syswarn(1, errno, "Cannot determine archive tape blocksize.");
1330 		return -1;
1331 	}
1332 
1333 	/*
1334 	 * read forward to the file mark, then back up in front of the filemark
1335 	 * (this is a bit paranoid, but should be safe to do).
1336 	 */
1337 	while ((res =
1338 #ifdef SUPPORT_RMT
1339 		rmtread_with_restart(arfd, scbuf, sizeof(scbuf))
1340 #else
1341 		read_with_restart(arfd, scbuf, sizeof(scbuf))
1342 #endif /* SUPPORT_RMT */
1343 	       ) > 0)
1344 		;
1345 	if (res < 0) {
1346 		syswarn(1, errno, "Unable to locate tape filemark.");
1347 		return -1;
1348 	}
1349 	mb.mt_op = MTBSF;
1350 	mb.mt_count = 1;
1351 	if (
1352 #ifdef SUPPORT_RMT
1353 	    rmtioctl(arfd, MTIOCTOP, &mb)
1354 #else
1355 	    ioctl(arfd, MTIOCTOP, &mb)
1356 #endif /* SUPPORT_RMT */
1357 	    < 0) {
1358 		syswarn(1, errno, "Unable to backspace over tape filemark.");
1359 		return -1;
1360 	}
1361 
1362 	/*
1363 	 * set lstrval so we know that the filemark has not been seen
1364 	 */
1365 	lstrval = 1;
1366 
1367 	/*
1368 	 * return if there was no padding
1369 	 */
1370 	if (padsz == 0)
1371 		return phyblk;
1372 
1373 	/*
1374 	 * make sure we can move backwards over the padding. (this should
1375 	 * never fail).
1376 	 */
1377 	if (padsz % phyblk) {
1378 		tty_warn(1, "Tape drive unable to backspace requested amount");
1379 		return -1;
1380 	}
1381 
1382 	/*
1383 	 * move backwards over the padding so the head is where it was when
1384 	 * we were first called (if required).
1385 	 */
1386 	mb.mt_op = MTBSR;
1387 	mb.mt_count = padsz/phyblk;
1388 	if (
1389 #ifdef SUPPORT_RMT
1390 	    rmtioctl(arfd, MTIOCTOP, &mb)
1391 #else
1392 	    ioctl(arfd, MTIOCTOP, &mb)
1393 #endif /* SUPPORT_RMT */
1394 	    < 0) {
1395 		syswarn(1, errno,
1396 		    "Unable to backspace tape over %ld pad blocks",
1397 		    (long)mb.mt_count);
1398 		return -1;
1399 	}
1400 	return phyblk;
1401 }
1402 #endif
1403 
1404 /*
1405  * ar_next()
1406  *	prompts the user for the next volume in this archive. For some devices
1407  *	we may allow the media to be changed. Otherwise a new archive is
1408  *	prompted for. By pax spec, if there is no controlling tty or an eof is
1409  *	read on tty input, we must quit pax.
1410  * Return:
1411  *	0 when ready to continue, -1 when all done
1412  */
1413 
1414 int
1415 ar_next(void)
1416 {
1417 	char buf[PAXPATHLEN+2];
1418 	static char *arcfree = NULL;
1419 	sigset_t o_mask;
1420 
1421 	/*
1422 	 * WE MUST CLOSE THE DEVICE. A lot of devices must see last close, (so
1423 	 * things like writing EOF etc will be done) (Watch out ar_close() can
1424 	 * also be called via a signal handler, so we must prevent a race.
1425 	 */
1426 	if (sigprocmask(SIG_BLOCK, &s_mask, &o_mask) < 0)
1427 		syswarn(0, errno, "Unable to set signal mask");
1428 	ar_close();
1429 	if (sigprocmask(SIG_SETMASK, &o_mask, (sigset_t *)NULL) < 0)
1430 		syswarn(0, errno, "Unable to restore signal mask");
1431 
1432 	if (done || !wr_trail || force_one_volume)
1433 		return -1;
1434 
1435 	if (!is_gnutar)
1436 		tty_prnt("\nATTENTION! %s archive volume change required.\n",
1437 		    argv0);
1438 
1439 	/*
1440 	 * if i/o is on stdin or stdout, we cannot reopen it (we do not know
1441 	 * the name), the user will be forced to type it in.
1442 	 */
1443 	if (strcmp(arcname, STDO) && strcmp(arcname, STDN) && (artyp != ISREG)
1444 	    && (artyp != ISPIPE)) {
1445 		if (artyp == ISTAPE
1446 #ifdef SUPPORT_RMT
1447 		    || artyp == ISRMT
1448 #endif /* SUPPORT_RMT */
1449 		    ) {
1450 			tty_prnt("%s ready for archive tape volume: %d\n",
1451 				arcname, arvol);
1452 			tty_prnt("Load the NEXT TAPE on the tape drive");
1453 		} else {
1454 			tty_prnt("%s ready for archive volume: %d\n",
1455 				arcname, arvol);
1456 			tty_prnt("Load the NEXT STORAGE MEDIA (if required)");
1457 		}
1458 
1459 		if ((act == ARCHIVE) || (act == APPND))
1460 			tty_prnt(" and make sure it is WRITE ENABLED.\n");
1461 		else
1462 			tty_prnt("\n");
1463 
1464 		for(;;) {
1465 			tty_prnt("Type \"y\" to continue, \".\" to quit %s,",
1466 				argv0);
1467 			tty_prnt(" or \"s\" to switch to new device.\nIf you");
1468 			tty_prnt(" cannot change storage media, type \"s\"\n");
1469 			tty_prnt("Is the device ready and online? > ");
1470 
1471 			if ((tty_read(buf,sizeof(buf))<0) || !strcmp(buf,".")){
1472 				done = 1;
1473 				lstrval = -1;
1474 				tty_prnt("Quitting %s!\n", argv0);
1475 				vfpart = 0;
1476 				return -1;
1477 			}
1478 
1479 			if ((buf[0] == '\0') || (buf[1] != '\0')) {
1480 				tty_prnt("%s unknown command, try again\n",buf);
1481 				continue;
1482 			}
1483 
1484 			switch (buf[0]) {
1485 			case 'y':
1486 			case 'Y':
1487 				/*
1488 				 * we are to continue with the same device
1489 				 */
1490 				if (ar_open(arcname) >= 0)
1491 					return 0;
1492 				tty_prnt("Cannot re-open %s, try again\n",
1493 					arcname);
1494 				continue;
1495 			case 's':
1496 			case 'S':
1497 				/*
1498 				 * user wants to open a different device
1499 				 */
1500 				tty_prnt("Switching to a different archive\n");
1501 				break;
1502 			default:
1503 				tty_prnt("%s unknown command, try again\n",buf);
1504 				continue;
1505 			}
1506 			break;
1507 		}
1508 	} else {
1509 		if (is_gnutar) {
1510 			tty_warn(1, "Unexpected EOF on archive file");
1511 			return -1;
1512 		}
1513 		tty_prnt("Ready for archive volume: %d\n", arvol);
1514 	}
1515 
1516 	/*
1517 	 * have to go to a different archive
1518 	 */
1519 	for (;;) {
1520 		tty_prnt("Input archive name or \".\" to quit %s.\n", argv0);
1521 		tty_prnt("Archive name > ");
1522 
1523 		if ((tty_read(buf, sizeof(buf)) < 0) || !strcmp(buf, ".")) {
1524 			done = 1;
1525 			lstrval = -1;
1526 			tty_prnt("Quitting %s!\n", argv0);
1527 			vfpart = 0;
1528 			return -1;
1529 		}
1530 		if (buf[0] == '\0') {
1531 			tty_prnt("Empty file name, try again\n");
1532 			continue;
1533 		}
1534 		if (!strcmp(buf, "..")) {
1535 			tty_prnt("Illegal file name: .. try again\n");
1536 			continue;
1537 		}
1538 		if (strlen(buf) > PAXPATHLEN) {
1539 			tty_prnt("File name too long, try again\n");
1540 			continue;
1541 		}
1542 
1543 		/*
1544 		 * try to open new archive
1545 		 */
1546 		if (ar_open(buf) >= 0) {
1547 			if (arcfree) {
1548 				(void)free(arcfree);
1549 				arcfree = NULL;
1550 			}
1551 			if ((arcfree = strdup(buf)) == NULL) {
1552 				done = 1;
1553 				lstrval = -1;
1554 				tty_warn(0, "Cannot save archive name.");
1555 				return -1;
1556 			}
1557 			arcname = arcfree;
1558 			break;
1559 		}
1560 		tty_prnt("Cannot open %s, try again\n", buf);
1561 		continue;
1562 	}
1563 	return 0;
1564 }
1565 
1566 /*
1567  * ar_start_gzip()
1568  * starts the compression/decompression process as a child, using magic
1569  * to keep the fd the same in the calling function (parent). possible
1570  * programs are GZIP_CMD, BZIP2_CMD, and COMPRESS_CMD.
1571  */
1572 void
1573 ar_start_gzip(int fd, const char *gzp, int wr)
1574 {
1575 	int fds[2];
1576 	const char *gzip_flags;
1577 
1578 	if (pipe(fds) < 0)
1579 		err(1, "could not pipe");
1580 	zpid = fork();
1581 	if (zpid < 0)
1582 		err(1, "could not fork");
1583 
1584 	/* parent */
1585 	if (zpid) {
1586 		if (wr)
1587 			dup2(fds[1], fd);
1588 		else
1589 			dup2(fds[0], fd);
1590 		close(fds[0]);
1591 		close(fds[1]);
1592 	} else {
1593 		if (wr) {
1594 			dup2(fds[0], STDIN_FILENO);
1595 			dup2(fd, STDOUT_FILENO);
1596 			gzip_flags = "-c";
1597 		} else {
1598 			dup2(fds[1], STDOUT_FILENO);
1599 			dup2(fd, STDIN_FILENO);
1600 			gzip_flags = "-dc";
1601 		}
1602 		close(fds[0]);
1603 		close(fds[1]);
1604 		if (execlp(gzp, gzp, gzip_flags, NULL) < 0)
1605 			err(1, "could not exec");
1606 		/* NOTREACHED */
1607 	}
1608 }
1609 
1610 static const char *
1611 timefmt(buf, size, sz, tm, unitstr)
1612 	char *buf;
1613 	size_t size;
1614 	off_t sz;
1615 	time_t tm;
1616 	const char *unitstr;
1617 {
1618 	(void)snprintf(buf, size, "%lu secs (" OFFT_F " %s/sec)",
1619 	    (unsigned long)tm, (OFFT_T)(sz / tm), unitstr);
1620 	return buf;
1621 }
1622 
1623 static const char *
1624 sizefmt(buf, size, sz)
1625 	char *buf;
1626 	size_t size;
1627 	off_t sz;
1628 {
1629 	(void)snprintf(buf, size, OFFT_F " bytes", (OFFT_T)sz);
1630 	return buf;
1631 }
1632 
1633 void
1634 ar_summary(int n)
1635 {
1636 	time_t secs;
1637 	int len;
1638 	char buf[BUFSIZ];
1639 	char tbuf[MAXPATHLEN/4];	/* XXX silly size! */
1640 	char s1buf[MAXPATHLEN/8];	/* XXX very silly size! */
1641 	char s2buf[MAXPATHLEN/8];	/* XXX very silly size! */
1642 	FILE *outf;
1643 
1644 	if (act == LIST)
1645 		outf = stdout;
1646 	else
1647 		outf = stderr;
1648 
1649 	/*
1650 	 * If we are called from a signal (n != 0), use snprintf(3) so that we
1651 	 * don't reenter stdio(3).
1652 	 */
1653 	(void)time(&secs);
1654 	if ((secs -= starttime) == 0)
1655 		secs = 1;
1656 
1657 	/*
1658 	 * If we have not determined the format yet, we just say how many bytes
1659 	 * we have skipped over looking for a header to id. there is no way we
1660 	 * could have written anything yet.
1661 	 */
1662 	if (frmt == NULL && act != COPY) {
1663 		len = snprintf(buf, sizeof(buf),
1664 		    "unknown format, %s skipped in %s\n",
1665 		    sizefmt(s1buf, sizeof(s1buf), rdcnt),
1666 		    timefmt(tbuf, sizeof(tbuf), rdcnt, secs, "bytes"));
1667 		if (n == 0)
1668 			(void)fprintf(outf, "%s: %s", argv0, buf);
1669 		else
1670 			(void)write(STDERR_FILENO, buf, len);
1671 		return;
1672 	}
1673 
1674 
1675 	if (n != 0 && *archd.name) {
1676 		len = snprintf(buf, sizeof(buf), "Working on `%s' (%s)\n",
1677 		    archd.name, sizefmt(s1buf, sizeof(s1buf), archd.sb.st_size));
1678 		(void)write(STDERR_FILENO, buf, len);
1679 		len = 0;
1680 	}
1681 
1682 
1683 	if (act == COPY) {
1684 		len = snprintf(buf, sizeof(buf),
1685 		    "%lu files in %s\n",
1686 		    (unsigned long)flcnt,
1687 		    timefmt(tbuf, sizeof(tbuf), flcnt, secs, "files"));
1688 	} else {
1689 		len = snprintf(buf, sizeof(buf),
1690 		    "%s vol %d, %lu files, %s read, %s written in %s\n",
1691 		    frmt->name, arvol-1, (unsigned long)flcnt,
1692 		    sizefmt(s1buf, sizeof(s1buf), rdcnt),
1693 		    sizefmt(s2buf, sizeof(s2buf), wrcnt),
1694 		    timefmt(tbuf, sizeof(tbuf), rdcnt + wrcnt, secs, "bytes"));
1695 	}
1696 	if (n == 0)
1697 		(void)fprintf(outf, "%s: %s", argv0, buf);
1698 	else
1699 		(void)write(STDERR_FILENO, buf, strlen(buf));
1700 }
1701 
1702 /*
1703  * ar_dochdir(name)
1704  *	change directory to name, and remember where we came from and
1705  *	where we change to (for ar_open).
1706  *
1707  *	Maybe we could try to be smart and only do the actual chdir
1708  *	when necessary to write a file read from the archive, but this
1709  *	is not easy to get right given the pax code structure.
1710  *
1711  *	Be sure to not leak descriptors!
1712  *
1713  *	We are called N * M times when extracting, and N times when
1714  *	writing archives, where
1715  *	N:	number of -C options
1716  *	M:	number of files in archive
1717  *
1718  * Returns 0 if all went well, else -1.
1719  */
1720 
1721 int
1722 ar_dochdir(const char *name)
1723 {
1724 	/* First fdochdir() back... */
1725 	if (fdochdir(cwdfd) == -1)
1726 		return -1;
1727 	if (dochdir(name) == -1)
1728 		return -1;
1729 	return 0;
1730 }
1731