xref: /freebsd/bin/pax/ar_io.c (revision 41466b50c1d5bfd1cf6adaae547a579a75d7c04e)
1 /*-
2  * Copyright (c) 1992 Keith Muller.
3  * Copyright (c) 1992, 1993
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * Keith Muller of the University of California, San Diego.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed by the University of
20  *	California, Berkeley and its contributors.
21  * 4. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  */
37 
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)ar_io.c	8.2 (Berkeley) 4/18/94";
41 #endif
42 static const char rcsid[] =
43   "$FreeBSD$";
44 #endif /* not lint */
45 
46 #include <sys/types.h>
47 #include <sys/ioctl.h>
48 #include <sys/mtio.h>
49 #include <sys/stat.h>
50 #include <sys/wait.h>
51 #include <err.h>
52 #include <errno.h>
53 #include <fcntl.h>
54 #include <signal.h>
55 #include <stdio.h>
56 #include <string.h>
57 #include <stdlib.h>
58 #include <unistd.h>
59 #include "pax.h"
60 #include "options.h"
61 #include "extern.h"
62 
63 /*
64  * Routines which deal directly with the archive I/O device/file.
65  */
66 
67 #define DMOD		0666		/* default mode of created archives */
68 #define EXT_MODE	O_RDONLY	/* open mode for list/extract */
69 #define AR_MODE		(O_WRONLY | O_CREAT | O_TRUNC)	/* mode for archive */
70 #define APP_MODE	O_RDWR		/* mode for append */
71 #define STDO		"<STDOUT>"	/* pseudo name for stdout */
72 #define STDN		"<STDIN>"	/* pseudo name for stdin */
73 static int arfd = -1;			/* archive file descriptor */
74 static int artyp = ISREG;		/* archive type: file/FIFO/tape */
75 static int arvol = 1;			/* archive volume number */
76 static int lstrval = -1;		/* return value from last i/o */
77 static int io_ok;			/* i/o worked on volume after resync */
78 static int did_io;			/* did i/o ever occur on volume? */
79 static int done;			/* set via tty termination */
80 static struct stat arsb;		/* stat of archive device at open */
81 static int invld_rec;			/* tape has out of spec record size */
82 static int wr_trail = 1;		/* trailer was rewritten in append */
83 static int can_unlnk = 0;		/* do we unlink null archives?  */
84 char *arcname;		  	/* printable name of archive */
85 const char *gzip_program;		/* name of gzip program */
86 static pid_t zpid = -1;			/* pid of child process */
87 
88 static int get_phys __P((void));
89 extern sigset_t s_mask;
90 static void ar_start_gzip __P((int, const char *, int));
91 
92 /*
93  * ar_open()
94  *	Opens the next archive volume. Determines the type of the device and
95  *	sets up block sizes as required by the archive device and the format.
96  *	Note: we may be called with name == NULL on the first open only.
97  * Return:
98  *	-1 on failure, 0 otherwise
99  */
100 
101 #ifdef __STDC__
102 int
103 ar_open(char *name)
104 #else
105 int
106 ar_open(name)
107 	char *name;
108 #endif
109 {
110 	struct mtget mb;
111 
112 	if (arfd != -1)
113 		(void)close(arfd);
114 	arfd = -1;
115 	can_unlnk = did_io = io_ok = invld_rec = 0;
116 	artyp = ISREG;
117 	flcnt = 0;
118 
119 	/*
120 	 * open based on overall operation mode
121 	 */
122 	switch (act) {
123 	case LIST:
124 	case EXTRACT:
125 		if (name == NULL) {
126 			arfd = STDIN_FILENO;
127 			arcname = STDN;
128 		} else if ((arfd = open(name, EXT_MODE, DMOD)) < 0)
129 			syswarn(0, errno, "Failed open to read on %s", name);
130 		if (arfd != -1 && gzip_program != NULL)
131 			ar_start_gzip(arfd, gzip_program, 0);
132 		break;
133 	case ARCHIVE:
134 		if (name == NULL) {
135 			arfd = STDOUT_FILENO;
136 			arcname = STDO;
137 		} else if ((arfd = open(name, AR_MODE, DMOD)) < 0)
138 			syswarn(0, errno, "Failed open to write on %s", name);
139 		else
140 			can_unlnk = 1;
141 		if (arfd != -1 && gzip_program != NULL)
142 			ar_start_gzip(arfd, gzip_program, 1);
143 		break;
144 	case APPND:
145 		if (name == NULL) {
146 			arfd = STDOUT_FILENO;
147 			arcname = STDO;
148 		} else if ((arfd = open(name, APP_MODE, DMOD)) < 0)
149 			syswarn(0, errno, "Failed open to read/write on %s",
150 				name);
151 		break;
152 	case COPY:
153 		/*
154 		 * arfd not used in COPY mode
155 		 */
156 		arcname = "<NONE>";
157 		lstrval = 1;
158 		return(0);
159 	}
160 	if (arfd < 0)
161 		return(-1);
162 
163 	if (chdname != NULL)
164 		if (chdir(chdname) != 0)
165 			syswarn(1, errno, "Failed chdir to %s", chdname);
166 	/*
167 	 * set up is based on device type
168 	 */
169 	if (fstat(arfd, &arsb) < 0) {
170 		syswarn(0, errno, "Failed stat on %s", arcname);
171 		(void)close(arfd);
172 		arfd = -1;
173 		can_unlnk = 0;
174 		return(-1);
175 	}
176 	if (S_ISDIR(arsb.st_mode)) {
177 		paxwarn(0, "Cannot write an archive on top of a directory %s",
178 		    arcname);
179 		(void)close(arfd);
180 		arfd = -1;
181 		can_unlnk = 0;
182 		return(-1);
183 	}
184 
185 	if (S_ISCHR(arsb.st_mode))
186 		artyp = ioctl(arfd, MTIOCGET, &mb) ? ISCHR : ISTAPE;
187 	else if (S_ISBLK(arsb.st_mode))
188 		artyp = ISBLK;
189 	else if ((lseek(arfd, (off_t)0L, SEEK_CUR) == -1) && (errno == ESPIPE))
190 		artyp = ISPIPE;
191 	else
192 		artyp = ISREG;
193 
194 	/*
195 	 * make sure we beyond any doubt that we only can unlink regular files
196 	 * we created
197 	 */
198 	if (artyp != ISREG)
199 		can_unlnk = 0;
200 	/*
201 	 * if we are writing, we are done
202 	 */
203 	if (act == ARCHIVE) {
204 		blksz = rdblksz = wrblksz;
205 		lstrval = 1;
206 		return(0);
207 	}
208 
209 	/*
210 	 * set default blksz on read. APPNDs writes rdblksz on the last volume
211 	 * On all new archive volumes, we shift to wrblksz (if the user
212 	 * specified one, otherwize we will continue to use rdblksz). We
213 	 * must to set blocksize based on what kind of device the archive is
214 	 * stored.
215 	 */
216 	switch(artyp) {
217 	case ISTAPE:
218 		/*
219 		 * Tape drives come in at least two flavors. Those that support
220 		 * variable sized records and those that have fixed sized
221 		 * records. They must be treated differently. For tape drives
222 		 * that support variable sized records, we must make large
223 		 * reads to make sure we get the entire record, otherwise we
224 		 * will just get the first part of the record (up to size we
225 		 * asked). Tapes with fixed sized records may or may not return
226 		 * multiple records in a single read. We really do not care
227 		 * what the physical record size is UNLESS we are going to
228 		 * append. (We will need the physical block size to rewrite
229 		 * the trailer). Only when we are appending do we go to the
230 		 * effort to figure out the true PHYSICAL record size.
231 		 */
232 		blksz = rdblksz = MAXBLK;
233 		break;
234 	case ISPIPE:
235 	case ISBLK:
236 	case ISCHR:
237 		/*
238 		 * Blocksize is not a major issue with these devices (but must
239 		 * be kept a multiple of 512). If the user specified a write
240 		 * block size, we use that to read. Under append, we must
241 		 * always keep blksz == rdblksz. Otherwise we go ahead and use
242 		 * the device optimal blocksize as (and if) returned by stat
243 		 * and if it is within pax specs.
244 		 */
245 		if ((act == APPND) && wrblksz) {
246 			blksz = rdblksz = wrblksz;
247 			break;
248 		}
249 
250 		if ((arsb.st_blksize > 0) && (arsb.st_blksize < MAXBLK) &&
251 		    ((arsb.st_blksize % BLKMULT) == 0))
252 			rdblksz = arsb.st_blksize;
253 		else
254 			rdblksz = DEVBLK;
255 		/*
256 		 * For performance go for large reads when we can without harm
257 		 */
258 		if ((act == APPND) || (artyp == ISCHR))
259 			blksz = rdblksz;
260 		else
261 			blksz = MAXBLK;
262 		break;
263 	case ISREG:
264 		/*
265 		 * if the user specified wrblksz works, use it. Under appends
266 		 * we must always keep blksz == rdblksz
267 		 */
268 		if ((act == APPND) && wrblksz && ((arsb.st_size%wrblksz)==0)){
269 			blksz = rdblksz = wrblksz;
270 			break;
271 		}
272 		/*
273 		 * See if we can find the blocking factor from the file size
274 		 */
275 		for (rdblksz = MAXBLK; rdblksz > 0; rdblksz -= BLKMULT)
276 			if ((arsb.st_size % rdblksz) == 0)
277 				break;
278 		/*
279 		 * When we cannot find a match, we may have a flawed archive.
280 		 */
281 		if (rdblksz <= 0)
282 			rdblksz = FILEBLK;
283 		/*
284 		 * for performance go for large reads when we can
285 		 */
286 		if (act == APPND)
287 			blksz = rdblksz;
288 		else
289 			blksz = MAXBLK;
290 		break;
291 	default:
292 		/*
293 		 * should never happen, worse case, slow...
294 		 */
295 		blksz = rdblksz = BLKMULT;
296 		break;
297 	}
298 	lstrval = 1;
299 	return(0);
300 }
301 
302 /*
303  * ar_close()
304  *	closes archive device, increments volume number, and prints i/o summary
305  */
306 #ifdef __STDC__
307 void
308 ar_close(void)
309 #else
310 void
311 ar_close()
312 #endif
313 {
314 
315 	if (arfd < 0) {
316 		did_io = io_ok = flcnt = 0;
317 		return;
318 	}
319 
320 	/*
321 	 * Close archive file. This may take a LONG while on tapes (we may be
322 	 * forced to wait for the rewind to complete) so tell the user what is
323 	 * going on (this avoids the user hitting control-c thinking pax is
324 	 * broken).
325 	 */
326 	if (vflag && (artyp == ISTAPE)) {
327 		if (vfpart)
328 			(void)putc('\n', listf);
329 		(void)fprintf(listf,
330 			"%s: Waiting for tape drive close to complete...",
331 			argv0);
332 		(void)fflush(listf);
333 	}
334 
335 	/*
336 	 * if nothing was written to the archive (and we created it), we remove
337 	 * it
338 	 */
339 	if (can_unlnk && (fstat(arfd, &arsb) == 0) && (S_ISREG(arsb.st_mode)) &&
340 	    (arsb.st_size == 0)) {
341 		(void)unlink(arcname);
342 		can_unlnk = 0;
343 	}
344 
345 	/*
346 	 * for a quick extract/list, pax frequently exits before the child
347 	 * process is done
348 	 */
349 	if ((act == LIST || act == EXTRACT) && nflag && zpid > 0) {
350 		int status;
351 		kill(zpid, SIGINT);
352 		waitpid(zpid, &status, 0);
353 	}
354 
355 	(void)close(arfd);
356 
357 	if (vflag && (artyp == ISTAPE)) {
358 		(void)fputs("done.\n", listf);
359 		vfpart = 0;
360 		(void)fflush(listf);
361 	}
362 	arfd = -1;
363 
364 	if (!io_ok && !did_io) {
365 		flcnt = 0;
366 		return;
367 	}
368 	did_io = io_ok = 0;
369 
370 	/*
371 	 * The volume number is only increased when the last device has data
372 	 * and we have already determined the archive format.
373 	 */
374 	if (frmt != NULL)
375 		++arvol;
376 
377 	if (!vflag) {
378 		flcnt = 0;
379 		return;
380 	}
381 
382 	/*
383 	 * Print out a summary of I/O for this archive volume.
384 	 */
385 	if (vfpart) {
386 		(void)putc('\n', listf);
387 		vfpart = 0;
388 	}
389 
390 	/*
391 	 * If we have not determined the format yet, we just say how many bytes
392 	 * we have skipped over looking for a header to id. there is no way we
393 	 * could have written anything yet.
394 	 */
395 	if (frmt == NULL) {
396 #	ifdef NET2_STAT
397 		(void)fprintf(listf, "%s: unknown format, %lu bytes skipped.\n",
398 #	else
399 		(void)fprintf(listf, "%s: unknown format, %qu bytes skipped.\n",
400 #	endif
401 		    argv0, rdcnt);
402 		(void)fflush(listf);
403 		flcnt = 0;
404 		return;
405 	}
406 
407 	if (strcmp(NM_CPIO, argv0) == 0)
408 		(void)fprintf(listf, "%qu blocks\n", (rdcnt ? rdcnt : wrcnt) / 5120);
409 	else if (strcmp(NM_TAR, argv0) != 0)
410 		(void)fprintf(listf,
411 #	ifdef NET2_STAT
412 		    "%s: %s vol %d, %lu files, %lu bytes read, %lu bytes written.\n",
413 #	else
414 		    "%s: %s vol %d, %lu files, %qu bytes read, %qu bytes written.\n",
415 #	endif
416 		    argv0, frmt->name, arvol-1, flcnt, rdcnt, wrcnt);
417 	(void)fflush(listf);
418 	flcnt = 0;
419 }
420 
421 /*
422  * ar_drain()
423  *	drain any archive format independent padding from an archive read
424  *	from a socket or a pipe. This is to prevent the process on the
425  *	other side of the pipe from getting a SIGPIPE (pax will stop
426  *	reading an archive once a format dependent trailer is detected).
427  */
428 #ifdef __STDC__
429 void
430 ar_drain(void)
431 #else
432 void
433 ar_drain()
434 #endif
435 {
436 	register int res;
437 	char drbuf[MAXBLK];
438 
439 	/*
440 	 * we only drain from a pipe/socket. Other devices can be closed
441 	 * without reading up to end of file. We sure hope that pipe is closed
442 	 * on the other side so we will get an EOF.
443 	 */
444 	if ((artyp != ISPIPE) || (lstrval <= 0))
445 		return;
446 
447 	/*
448 	 * keep reading until pipe is drained
449 	 */
450 	while ((res = read(arfd, drbuf, sizeof(drbuf))) > 0)
451 		;
452 	lstrval = res;
453 }
454 
455 /*
456  * ar_set_wr()
457  *	Set up device right before switching from read to write in an append.
458  *	device dependent code (if required) to do this should be added here.
459  *	For all archive devices we are already positioned at the place we want
460  *	to start writing when this routine is called.
461  * Return:
462  *	0 if all ready to write, -1 otherwise
463  */
464 
465 #ifdef __STDC__
466 int
467 ar_set_wr(void)
468 #else
469 int
470 ar_set_wr()
471 #endif
472 {
473 	off_t cpos;
474 
475 	/*
476 	 * we must make sure the trailer is rewritten on append, ar_next()
477 	 * will stop us if the archive containing the trailer was not written
478 	 */
479 	wr_trail = 0;
480 
481 	/*
482 	 * Add any device dependent code as required here
483 	 */
484 	if (artyp != ISREG)
485 		return(0);
486 	/*
487 	 * Ok we have an archive in a regular file. If we were rewriting a
488 	 * file, we must get rid of all the stuff after the current offset
489 	 * (it was not written by pax).
490 	 */
491 	if (((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0) ||
492 	    (ftruncate(arfd, cpos) < 0)) {
493 		syswarn(1, errno, "Unable to truncate archive file");
494 		return(-1);
495 	}
496 	return(0);
497 }
498 
499 /*
500  * ar_app_ok()
501  *	check if the last volume in the archive allows appends. We cannot check
502  *	this until we are ready to write since there is no spec that says all
503  *	volumes in a single archive have to be of the same type...
504  * Return:
505  *	0 if we can append, -1 otherwise.
506  */
507 
508 #ifdef __STDC__
509 int
510 ar_app_ok(void)
511 #else
512 int
513 ar_app_ok()
514 #endif
515 {
516 	if (artyp == ISPIPE) {
517 		paxwarn(1, "Cannot append to an archive obtained from a pipe.");
518 		return(-1);
519 	}
520 
521 	if (!invld_rec)
522 		return(0);
523 	paxwarn(1,"Cannot append, device record size %d does not support %s spec",
524 		rdblksz, argv0);
525 	return(-1);
526 }
527 
528 /*
529  * ar_read()
530  *	read up to a specified number of bytes from the archive into the
531  *	supplied buffer. When dealing with tapes we may not always be able to
532  *	read what we want.
533  * Return:
534  *	Number of bytes in buffer. 0 for end of file, -1 for a read error.
535  */
536 
537 #ifdef __STDC__
538 int
539 ar_read(register char *buf, register int cnt)
540 #else
541 int
542 ar_read(buf, cnt)
543 	register char *buf;
544 	register int cnt;
545 #endif
546 {
547 	register int res = 0;
548 
549 	/*
550 	 * if last i/o was in error, no more reads until reset or new volume
551 	 */
552 	if (lstrval <= 0)
553 		return(lstrval);
554 
555 	/*
556 	 * how we read must be based on device type
557 	 */
558 	switch (artyp) {
559 	case ISTAPE:
560 		if ((res = read(arfd, buf, cnt)) > 0) {
561 			/*
562 			 * CAUTION: tape systems may not always return the same
563 			 * sized records so we leave blksz == MAXBLK. The
564 			 * physical record size that a tape drive supports is
565 			 * very hard to determine in a uniform and portable
566 			 * manner.
567 			 */
568 			io_ok = 1;
569 			if (res != rdblksz) {
570 				/*
571 				 * Record size changed. If this is happens on
572 				 * any record after the first, we probably have
573 				 * a tape drive which has a fixed record size
574 				 * we are getting multiple records in a single
575 				 * read). Watch out for record blocking that
576 				 * violates pax spec (must be a multiple of
577 				 * BLKMULT).
578 				 */
579 				rdblksz = res;
580 				if (rdblksz % BLKMULT)
581 					invld_rec = 1;
582 			}
583 			return(res);
584 		}
585 		break;
586 	case ISREG:
587 	case ISBLK:
588 	case ISCHR:
589 	case ISPIPE:
590 	default:
591 		/*
592 		 * Files are so easy to deal with. These other things cannot
593 		 * be trusted at all. So when we are dealing with character
594 		 * devices and pipes we just take what they have ready for us
595 		 * and return. Trying to do anything else with them runs the
596 		 * risk of failure.
597 		 */
598 		if ((res = read(arfd, buf, cnt)) > 0) {
599 			io_ok = 1;
600 			return(res);
601 		}
602 		break;
603 	}
604 
605 	/*
606 	 * We are in trouble at this point, something is broken...
607 	 */
608 	lstrval = res;
609 	if (res < 0)
610 		syswarn(1, errno, "Failed read on archive volume %d", arvol);
611 	else
612 		paxwarn(0, "End of archive volume %d reached", arvol);
613 	return(res);
614 }
615 
616 /*
617  * ar_write()
618  *	Write a specified number of bytes in supplied buffer to the archive
619  *	device so it appears as a single "block". Deals with errors and tries
620  *	to recover when faced with short writes.
621  * Return:
622  *	Number of bytes written. 0 indicates end of volume reached and with no
623  *	flaws (as best that can be detected). A -1 indicates an unrecoverable
624  *	error in the archive occured.
625  */
626 
627 #ifdef __STDC__
628 int
629 ar_write(register char *buf, register int bsz)
630 #else
631 int
632 ar_write(buf, bsz)
633 	register char *buf;
634 	register int bsz;
635 #endif
636 {
637 	register int res;
638 	off_t cpos;
639 
640 	/*
641 	 * do not allow pax to create a "bad" archive. Once a write fails on
642 	 * an archive volume prevent further writes to it.
643 	 */
644 	if (lstrval <= 0)
645 		return(lstrval);
646 
647 	if ((res = write(arfd, buf, bsz)) == bsz) {
648 		wr_trail = 1;
649 		io_ok = 1;
650 		return(bsz);
651 	}
652 	/*
653 	 * write broke, see what we can do with it. We try to send any partial
654 	 * writes that may violate pax spec to the next archive volume.
655 	 */
656 	if (res < 0)
657 		lstrval = res;
658 	else
659 		lstrval = 0;
660 
661 	switch (artyp) {
662 	case ISREG:
663 		if ((res > 0) && (res % BLKMULT)) {
664 			/*
665 		 	 * try to fix up partial writes which are not BLKMULT
666 			 * in size by forcing the runt record to next archive
667 			 * volume
668 		 	 */
669 			if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0)
670 				break;
671 			cpos -= (off_t)res;
672 			if (ftruncate(arfd, cpos) < 0)
673 				break;
674 			res = lstrval = 0;
675 			break;
676 		}
677 		if (res >= 0)
678 			break;
679 		/*
680 		 * if file is out of space, handle it like a return of 0
681 		 */
682 		if ((errno == ENOSPC) || (errno == EFBIG) || (errno == EDQUOT))
683 			res = lstrval = 0;
684 		break;
685 	case ISTAPE:
686 	case ISCHR:
687 	case ISBLK:
688 		if (res >= 0)
689 			break;
690 		if (errno == EACCES) {
691 			paxwarn(0, "Write failed, archive is write protected.");
692 			res = lstrval = 0;
693 			return(0);
694 		}
695 		/*
696 		 * see if we reached the end of media, if so force a change to
697 		 * the next volume
698 		 */
699 		if ((errno == ENOSPC) || (errno == EIO) || (errno == ENXIO))
700 			res = lstrval = 0;
701 		break;
702 	case ISPIPE:
703 	default:
704 		/*
705 		 * we cannot fix errors to these devices
706 		 */
707 		break;
708 	}
709 
710 	/*
711 	 * Better tell the user the bad news...
712 	 * if this is a block aligned archive format, we may have a bad archive
713 	 * if the format wants the header to start at a BLKMULT boundary. While
714 	 * we can deal with the mis-aligned data, it violates spec and other
715 	 * archive readers will likely fail. if the format is not block
716 	 * aligned, the user may be lucky (and the archive is ok).
717 	 */
718 	if (res >= 0) {
719 		if (res > 0)
720 			wr_trail = 1;
721 		io_ok = 1;
722 	}
723 
724 	/*
725 	 * If we were trying to rewrite the trailer and it didn't work, we
726 	 * must quit right away.
727 	 */
728 	if (!wr_trail && (res <= 0)) {
729 		paxwarn(1,"Unable to append, trailer re-write failed. Quitting.");
730 		return(res);
731 	}
732 
733 	if (res == 0)
734 		paxwarn(0, "End of archive volume %d reached", arvol);
735 	else if (res < 0)
736 		syswarn(1, errno, "Failed write to archive volume: %d", arvol);
737 	else if (!frmt->blkalgn || ((res % frmt->blkalgn) == 0))
738 		paxwarn(0,"WARNING: partial archive write. Archive MAY BE FLAWED");
739 	else
740 		paxwarn(1,"WARNING: partial archive write. Archive IS FLAWED");
741 	return(res);
742 }
743 
744 /*
745  * ar_rdsync()
746  *	Try to move past a bad spot on a flawed archive as needed to continue
747  *	I/O. Clears error flags to allow I/O to continue.
748  * Return:
749  *	0 when ok to try i/o again, -1 otherwise.
750  */
751 
752 #ifdef __STDC__
753 int
754 ar_rdsync(void)
755 #else
756 int
757 ar_rdsync()
758 #endif
759 {
760 	long fsbz;
761 	off_t cpos;
762 	off_t mpos;
763 	struct mtop mb;
764 
765 	/*
766 	 * Fail resync attempts at user request (done) or this is going to be
767 	 * an update/append to a existing archive. if last i/o hit media end,
768 	 * we need to go to the next volume not try a resync
769 	 */
770 	if ((done > 0) || (lstrval == 0))
771 		return(-1);
772 
773 	if ((act == APPND) || (act == ARCHIVE)) {
774 		paxwarn(1, "Cannot allow updates to an archive with flaws.");
775 		return(-1);
776 	}
777 	if (io_ok)
778 		did_io = 1;
779 
780 	switch(artyp) {
781 	case ISTAPE:
782 		/*
783 		 * if the last i/o was a successful data transfer, we assume
784 		 * the fault is just a bad record on the tape that we are now
785 		 * past. If we did not get any data since the last resync try
786 		 * to move the tape forward one PHYSICAL record past any
787 		 * damaged tape section. Some tape drives are stubborn and need
788 		 * to be pushed.
789 		 */
790 		if (io_ok) {
791 			io_ok = 0;
792 			lstrval = 1;
793 			break;
794 		}
795 		mb.mt_op = MTFSR;
796 		mb.mt_count = 1;
797 		if (ioctl(arfd, MTIOCTOP, &mb) < 0)
798 			break;
799 		lstrval = 1;
800 		break;
801 	case ISREG:
802 	case ISCHR:
803 	case ISBLK:
804 		/*
805 		 * try to step over the bad part of the device.
806 		 */
807 		io_ok = 0;
808 		if (((fsbz = arsb.st_blksize) <= 0) || (artyp != ISREG))
809 			fsbz = BLKMULT;
810 		if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0)
811 			break;
812 		mpos = fsbz - (cpos % (off_t)fsbz);
813 		if (lseek(arfd, mpos, SEEK_CUR) < 0)
814 			break;
815 		lstrval = 1;
816 		break;
817 	case ISPIPE:
818 	default:
819 		/*
820 		 * cannot recover on these archive device types
821 		 */
822 		io_ok = 0;
823 		break;
824 	}
825 	if (lstrval <= 0) {
826 		paxwarn(1, "Unable to recover from an archive read failure.");
827 		return(-1);
828 	}
829 	paxwarn(0, "Attempting to recover from an archive read failure.");
830 	return(0);
831 }
832 
833 /*
834  * ar_fow()
835  *	Move the I/O position within the archive foward the specified number of
836  *	bytes as supported by the device. If we cannot move the requested
837  *	number of bytes, return the actual number of bytes moved in skipped.
838  * Return:
839  *	0 if moved the requested distance, -1 on complete failure, 1 on
840  *	partial move (the amount moved is in skipped)
841  */
842 
843 #ifdef __STDC__
844 int
845 ar_fow(off_t sksz, off_t *skipped)
846 #else
847 int
848 ar_fow(sksz, skipped)
849 	off_t sksz;
850 	off_t *skipped;
851 #endif
852 {
853 	off_t cpos;
854 	off_t mpos;
855 
856 	*skipped = 0;
857 	if (sksz <= 0)
858 		return(0);
859 
860 	/*
861 	 * we cannot move foward at EOF or error
862 	 */
863 	if (lstrval <= 0)
864 		return(lstrval);
865 
866 	/*
867 	 * Safer to read forward on devices where it is hard to find the end of
868 	 * the media without reading to it. With tapes we cannot be sure of the
869 	 * number of physical blocks to skip (we do not know physical block
870 	 * size at this point), so we must only read foward on tapes!
871 	 */
872 	if (artyp != ISREG)
873 		return(0);
874 
875 	/*
876 	 * figure out where we are in the archive
877 	 */
878 	if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) >= 0) {
879 		/*
880 	 	 * we can be asked to move farther than there are bytes in this
881 		 * volume, if so, just go to file end and let normal buf_fill()
882 		 * deal with the end of file (it will go to next volume by
883 		 * itself)
884 	 	 */
885 		if ((mpos = cpos + sksz) > arsb.st_size) {
886 			*skipped = arsb.st_size - cpos;
887 			mpos = arsb.st_size;
888 		} else
889 			*skipped = sksz;
890 		if (lseek(arfd, mpos, SEEK_SET) >= 0)
891 			return(0);
892 	}
893 	syswarn(1, errno, "Forward positioning operation on archive failed");
894 	lstrval = -1;
895 	return(-1);
896 }
897 
898 /*
899  * ar_rev()
900  *	move the i/o position within the archive backwards the specified byte
901  *	count as supported by the device. With tapes drives we RESET rdblksz to
902  *	the PHYSICAL blocksize.
903  *	NOTE: We should only be called to move backwards so we can rewrite the
904  *	last records (the trailer) of an archive (APPEND).
905  * Return:
906  *	0 if moved the requested distance, -1 on complete failure
907  */
908 
909 #ifdef __STDC__
910 int
911 ar_rev(off_t sksz)
912 #else
913 int
914 ar_rev(sksz)
915 	off_t sksz;
916 #endif
917 {
918 	off_t cpos;
919 	struct mtop mb;
920 	register int phyblk;
921 
922 	/*
923 	 * make sure we do not have try to reverse on a flawed archive
924 	 */
925 	if (lstrval < 0)
926 		return(lstrval);
927 
928 	switch(artyp) {
929 	case ISPIPE:
930 		if (sksz <= 0)
931 			break;
932 		/*
933 		 * cannot go backwards on these critters
934 		 */
935 		paxwarn(1, "Reverse positioning on pipes is not supported.");
936 		lstrval = -1;
937 		return(-1);
938 	case ISREG:
939 	case ISBLK:
940 	case ISCHR:
941 	default:
942 		if (sksz <= 0)
943 			break;
944 
945 		/*
946 		 * For things other than files, backwards movement has a very
947 		 * high probability of failure as we really do not know the
948 		 * true attributes of the device we are talking to (the device
949 		 * may not even have the ability to lseek() in any direction).
950 		 * First we figure out where we are in the archive.
951 		 */
952 		if ((cpos = lseek(arfd, (off_t)0L, SEEK_CUR)) < 0) {
953 			syswarn(1, errno,
954 			   "Unable to obtain current archive byte offset");
955 			lstrval = -1;
956 			return(-1);
957 		}
958 
959 		/*
960 		 * we may try to go backwards past the start when the archive
961 		 * is only a single record. If this hapens and we are on a
962 		 * multi volume archive, we need to go to the end of the
963 		 * previous volume and continue our movement backwards from
964 		 * there.
965 		 */
966 		if ((cpos -= sksz) < (off_t)0L) {
967 			if (arvol > 1) {
968 				/*
969 				 * this should never happen
970 				 */
971 				paxwarn(1,"Reverse position on previous volume.");
972 				lstrval = -1;
973 				return(-1);
974 			}
975 			cpos = (off_t)0L;
976 		}
977 		if (lseek(arfd, cpos, SEEK_SET) < 0) {
978 			syswarn(1, errno, "Unable to seek archive backwards");
979 			lstrval = -1;
980 			return(-1);
981 		}
982 		break;
983 	case ISTAPE:
984 		/*
985 	 	 * Calculate and move the proper number of PHYSICAL tape
986 		 * blocks. If the sksz is not an even multiple of the physical
987 		 * tape size, we cannot do the move (this should never happen).
988 		 * (We also cannot handler trailers spread over two vols).
989 		 * get_phys() also makes sure we are in front of the filemark.
990 	 	 */
991 		if ((phyblk = get_phys()) <= 0) {
992 			lstrval = -1;
993 			return(-1);
994 		}
995 
996 		/*
997 		 * make sure future tape reads only go by physical tape block
998 		 * size (set rdblksz to the real size).
999 		 */
1000 		rdblksz = phyblk;
1001 
1002 		/*
1003 		 * if no movement is required, just return (we must be after
1004 		 * get_phys() so the physical blocksize is properly set)
1005 		 */
1006 		if (sksz <= 0)
1007 			break;
1008 
1009 		/*
1010 		 * ok we have to move. Make sure the tape drive can do it.
1011 		 */
1012 		if (sksz % phyblk) {
1013 			paxwarn(1,
1014 			    "Tape drive unable to backspace requested amount");
1015 			lstrval = -1;
1016 			return(-1);
1017 		}
1018 
1019 		/*
1020 		 * move backwards the requested number of bytes
1021 		 */
1022 		mb.mt_op = MTBSR;
1023 		mb.mt_count = sksz/phyblk;
1024 		if (ioctl(arfd, MTIOCTOP, &mb) < 0) {
1025 			syswarn(1,errno, "Unable to backspace tape %d blocks.",
1026 			    mb.mt_count);
1027 			lstrval = -1;
1028 			return(-1);
1029 		}
1030 		break;
1031 	}
1032 	lstrval = 1;
1033 	return(0);
1034 }
1035 
1036 /*
1037  * get_phys()
1038  *	Determine the physical block size on a tape drive. We need the physical
1039  *	block size so we know how many bytes we skip over when we move with
1040  *	mtio commands. We also make sure we are BEFORE THE TAPE FILEMARK when
1041  *	return.
1042  *	This is one really SLOW routine...
1043  * Return:
1044  *	physical block size if ok (ok > 0), -1 otherwise
1045  */
1046 
1047 #ifdef __STDC__
1048 static int
1049 get_phys(void)
1050 #else
1051 static int
1052 get_phys()
1053 #endif
1054 {
1055 	register int padsz = 0;
1056 	register int res;
1057 	register int phyblk;
1058 	struct mtop mb;
1059 	char scbuf[MAXBLK];
1060 
1061 	/*
1062 	 * move to the file mark, and then back up one record and read it.
1063 	 * this should tell us the physical record size the tape is using.
1064 	 */
1065 	if (lstrval == 1) {
1066 		/*
1067 		 * we know we are at file mark when we get back a 0 from
1068 		 * read()
1069 		 */
1070 		while ((res = read(arfd, scbuf, sizeof(scbuf))) > 0)
1071 			padsz += res;
1072 		if (res < 0) {
1073 			syswarn(1, errno, "Unable to locate tape filemark.");
1074 			return(-1);
1075 		}
1076 	}
1077 
1078 	/*
1079 	 * move backwards over the file mark so we are at the end of the
1080 	 * last record.
1081 	 */
1082 	mb.mt_op = MTBSF;
1083 	mb.mt_count = 1;
1084 	if (ioctl(arfd, MTIOCTOP, &mb) < 0) {
1085 		syswarn(1, errno, "Unable to backspace over tape filemark.");
1086 		return(-1);
1087 	}
1088 
1089 	/*
1090 	 * move backwards so we are in front of the last record and read it to
1091 	 * get physical tape blocksize.
1092 	 */
1093 	mb.mt_op = MTBSR;
1094 	mb.mt_count = 1;
1095 	if (ioctl(arfd, MTIOCTOP, &mb) < 0) {
1096 		syswarn(1, errno, "Unable to backspace over last tape block.");
1097 		return(-1);
1098 	}
1099 	if ((phyblk = read(arfd, scbuf, sizeof(scbuf))) <= 0) {
1100 		syswarn(1, errno, "Cannot determine archive tape blocksize.");
1101 		return(-1);
1102 	}
1103 
1104 	/*
1105 	 * read foward to the file mark, then back up in front of the filemark
1106 	 * (this is a bit paranoid, but should be safe to do).
1107 	 */
1108 	while ((res = read(arfd, scbuf, sizeof(scbuf))) > 0)
1109 		;
1110 	if (res < 0) {
1111 		syswarn(1, errno, "Unable to locate tape filemark.");
1112 		return(-1);
1113 	}
1114 	mb.mt_op = MTBSF;
1115 	mb.mt_count = 1;
1116 	if (ioctl(arfd, MTIOCTOP, &mb) < 0) {
1117 		syswarn(1, errno, "Unable to backspace over tape filemark.");
1118 		return(-1);
1119 	}
1120 
1121 	/*
1122 	 * set lstrval so we know that the filemark has not been seen
1123 	 */
1124 	lstrval = 1;
1125 
1126 	/*
1127 	 * return if there was no padding
1128 	 */
1129 	if (padsz == 0)
1130 		return(phyblk);
1131 
1132 	/*
1133 	 * make sure we can move backwards over the padding. (this should
1134 	 * never fail).
1135 	 */
1136 	if (padsz % phyblk) {
1137 		paxwarn(1, "Tape drive unable to backspace requested amount");
1138 		return(-1);
1139 	}
1140 
1141 	/*
1142 	 * move backwards over the padding so the head is where it was when
1143 	 * we were first called (if required).
1144 	 */
1145 	mb.mt_op = MTBSR;
1146 	mb.mt_count = padsz/phyblk;
1147 	if (ioctl(arfd, MTIOCTOP, &mb) < 0) {
1148 		syswarn(1,errno,"Unable to backspace tape over %d pad blocks",
1149 		    mb.mt_count);
1150 		return(-1);
1151 	}
1152 	return(phyblk);
1153 }
1154 
1155 /*
1156  * ar_next()
1157  *	prompts the user for the next volume in this archive. For some devices
1158  *	we may allow the media to be changed. Otherwise a new archive is
1159  *	prompted for. By pax spec, if there is no controlling tty or an eof is
1160  *	read on tty input, we must quit pax.
1161  * Return:
1162  *	0 when ready to continue, -1 when all done
1163  */
1164 
1165 #ifdef __STDC__
1166 int
1167 ar_next(void)
1168 #else
1169 int
1170 ar_next()
1171 #endif
1172 {
1173 	char buf[PAXPATHLEN+2];
1174 	static int freeit = 0;
1175 	sigset_t o_mask;
1176 
1177 	/*
1178 	 * WE MUST CLOSE THE DEVICE. A lot of devices must see last close, (so
1179 	 * things like writing EOF etc will be done) (Watch out ar_close() can
1180 	 * also be called via a signal handler, so we must prevent a race.
1181 	 */
1182 	if (sigprocmask(SIG_BLOCK, &s_mask, &o_mask) < 0)
1183 		syswarn(0, errno, "Unable to set signal mask");
1184 	ar_close();
1185 	if (sigprocmask(SIG_SETMASK, &o_mask, NULL) < 0)
1186 		syswarn(0, errno, "Unable to restore signal mask");
1187 
1188 	if (done || !wr_trail || strcmp(NM_TAR, argv0) == 0)
1189 		return(-1);
1190 
1191 	tty_prnt("\nATTENTION! %s archive volume change required.\n", argv0);
1192 
1193 	/*
1194 	 * if i/o is on stdin or stdout, we cannot reopen it (we do not know
1195 	 * the name), the user will be forced to type it in.
1196 	 */
1197 	if (strcmp(arcname, STDO) && strcmp(arcname, STDN) && (artyp != ISREG)
1198 	    && (artyp != ISPIPE)) {
1199 		if (artyp == ISTAPE) {
1200 			tty_prnt("%s ready for archive tape volume: %d\n",
1201 				arcname, arvol);
1202 			tty_prnt("Load the NEXT TAPE on the tape drive");
1203 		} else {
1204 			tty_prnt("%s ready for archive volume: %d\n",
1205 				arcname, arvol);
1206 			tty_prnt("Load the NEXT STORAGE MEDIA (if required)");
1207 		}
1208 
1209 		if ((act == ARCHIVE) || (act == APPND))
1210 			tty_prnt(" and make sure it is WRITE ENABLED.\n");
1211 		else
1212 			tty_prnt("\n");
1213 
1214 		for(;;) {
1215 			tty_prnt("Type \"y\" to continue, \".\" to quit %s,",
1216 				argv0);
1217 			tty_prnt(" or \"s\" to switch to new device.\nIf you");
1218 			tty_prnt(" cannot change storage media, type \"s\"\n");
1219 			tty_prnt("Is the device ready and online? > ");
1220 
1221 			if ((tty_read(buf,sizeof(buf))<0) || !strcmp(buf,".")){
1222 				done = 1;
1223 				lstrval = -1;
1224 				tty_prnt("Quitting %s!\n", argv0);
1225 				vfpart = 0;
1226 				return(-1);
1227 			}
1228 
1229 			if ((buf[0] == '\0') || (buf[1] != '\0')) {
1230 				tty_prnt("%s unknown command, try again\n",buf);
1231 				continue;
1232 			}
1233 
1234 			switch (buf[0]) {
1235 			case 'y':
1236 			case 'Y':
1237 				/*
1238 				 * we are to continue with the same device
1239 				 */
1240 				if (ar_open(arcname) >= 0)
1241 					return(0);
1242 				tty_prnt("Cannot re-open %s, try again\n",
1243 					arcname);
1244 				continue;
1245 			case 's':
1246 			case 'S':
1247 				/*
1248 				 * user wants to open a different device
1249 				 */
1250 				tty_prnt("Switching to a different archive\n");
1251 				break;
1252 			default:
1253 				tty_prnt("%s unknown command, try again\n",buf);
1254 				continue;
1255 			}
1256 			break;
1257 		}
1258 	} else
1259 		tty_prnt("Ready for archive volume: %d\n", arvol);
1260 
1261 	/*
1262 	 * have to go to a different archive
1263 	 */
1264 	for (;;) {
1265 		tty_prnt("Input archive name or \".\" to quit %s.\n", argv0);
1266 		tty_prnt("Archive name > ");
1267 
1268 		if ((tty_read(buf, sizeof(buf)) < 0) || !strcmp(buf, ".")) {
1269 			done = 1;
1270 			lstrval = -1;
1271 			tty_prnt("Quitting %s!\n", argv0);
1272 			vfpart = 0;
1273 			return(-1);
1274 		}
1275 		if (buf[0] == '\0') {
1276 			tty_prnt("Empty file name, try again\n");
1277 			continue;
1278 		}
1279 		if (!strcmp(buf, "..")) {
1280 			tty_prnt("Illegal file name: .. try again\n");
1281 			continue;
1282 		}
1283 		if (strlen(buf) > PAXPATHLEN) {
1284 			tty_prnt("File name too long, try again\n");
1285 			continue;
1286 		}
1287 
1288 		/*
1289 		 * try to open new archive
1290 		 */
1291 		if (ar_open(buf) >= 0) {
1292 			if (freeit) {
1293 				(void)free(arcname);
1294 				freeit = 0;
1295 			}
1296 			if ((arcname = strdup(buf)) == NULL) {
1297 				done = 1;
1298 				lstrval = -1;
1299 				paxwarn(0, "Cannot save archive name.");
1300 				return(-1);
1301 			}
1302 			freeit = 1;
1303 			break;
1304 		}
1305 		tty_prnt("Cannot open %s, try again\n", buf);
1306 		continue;
1307 	}
1308 	return(0);
1309 }
1310 
1311 /*
1312  * ar_start_gzip()
1313  * starts the gzip compression/decompression process as a child, using magic
1314  * to keep the fd the same in the calling function (parent).
1315  */
1316 void
1317 ar_start_gzip(int fd, const char *gzip_program, int wr)
1318 {
1319 	int fds[2];
1320 	char *gzip_flags;
1321 
1322 	if (pipe(fds) < 0)
1323 		err(1, "could not pipe");
1324 	zpid = fork();
1325 	if (zpid < 0)
1326 		err(1, "could not fork");
1327 
1328 	/* parent */
1329 	if (zpid) {
1330 		if (wr)
1331 			dup2(fds[1], fd);
1332 		else
1333 			dup2(fds[0], fd);
1334 		close(fds[0]);
1335 		close(fds[1]);
1336 	} else {
1337 		if (wr) {
1338 			dup2(fds[0], STDIN_FILENO);
1339 			dup2(fd, STDOUT_FILENO);
1340 			gzip_flags = "-c";
1341 		} else {
1342 			dup2(fds[1], STDOUT_FILENO);
1343 			dup2(fd, STDIN_FILENO);
1344 			gzip_flags = "-dc";
1345 		}
1346 		close(fds[0]);
1347 		close(fds[1]);
1348 		if (execlp(gzip_program, gzip_program, gzip_flags,
1349 		    (char *)NULL) < 0)
1350 			err(1, "could not exec");
1351 		/* NOTREACHED */
1352 	}
1353 }
1354