xref: /freebsd/bin/pax/ar_subs.c (revision 8881d206f4e68b564c2c5f50fc717086fc3e827a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
37 #if 0
38 static char sccsid[] = "@(#)ar_subs.c	8.2 (Berkeley) 4/18/94";
39 #endif
40 #endif /* not lint */
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43 
44 #include <sys/types.h>
45 #include <sys/time.h>
46 #include <sys/stat.h>
47 #include <signal.h>
48 #include <string.h>
49 #include <stdio.h>
50 #include <fcntl.h>
51 #include <errno.h>
52 #include <unistd.h>
53 #include "pax.h"
54 #include "extern.h"
55 
56 static void wr_archive(ARCHD *, int is_app);
57 static int get_arc(void);
58 static int next_head(ARCHD *);
59 
60 /*
61  * Routines which control the overall operation modes of pax as specified by
62  * the user: list, append, read ...
63  */
64 
65 static char hdbuf[BLKMULT];		/* space for archive header on read */
66 u_long flcnt;				/* number of files processed */
67 
68 /*
69  * list()
70  *	list the contents of an archive which match user supplied pattern(s)
71  *	(no pattern matches all).
72  */
73 
74 void
75 list(void)
76 {
77 	ARCHD *arcn;
78 	int res;
79 	ARCHD archd;
80 	time_t now;
81 
82 	arcn = &archd;
83 	/*
84 	 * figure out archive type; pass any format specific options to the
85 	 * archive option processing routine; call the format init routine. We
86 	 * also save current time for ls_list() so we do not make a system
87 	 * call for each file we need to print. If verbose (vflag) start up
88 	 * the name and group caches.
89 	 */
90 	if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
91 	    ((*frmt->st_rd)() < 0))
92 		return;
93 
94 	if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
95 		return;
96 
97 	now = time(NULL);
98 
99 	/*
100 	 * step through the archive until the format says it is done
101 	 */
102 	while (next_head(arcn) == 0) {
103 		/*
104 		 * check for pattern, and user specified options match.
105 		 * When all patterns are matched we are done.
106 		 */
107 		if ((res = pat_match(arcn)) < 0)
108 			break;
109 
110 		if ((res == 0) && (sel_chk(arcn) == 0)) {
111 			/*
112 			 * pattern resulted in a selected file
113 			 */
114 			if (pat_sel(arcn) < 0)
115 				break;
116 
117 			/*
118 			 * modify the name as requested by the user if name
119 			 * survives modification, do a listing of the file
120 			 */
121 			if ((res = mod_name(arcn)) < 0)
122 				break;
123 			if (res == 0)
124 				ls_list(arcn, now, stdout);
125 		}
126 
127 		/*
128 		 * skip to next archive format header using values calculated
129 		 * by the format header read routine
130 		 */
131 		if (rd_skip(arcn->skip + arcn->pad) == 1)
132 			break;
133 	}
134 
135 	/*
136 	 * all done, let format have a chance to cleanup, and make sure that
137 	 * the patterns supplied by the user were all matched
138 	 */
139 	(void)(*frmt->end_rd)();
140 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
141 	ar_close();
142 	pat_chk();
143 }
144 
145 /*
146  * extract()
147  *	extract the member(s) of an archive as specified by user supplied
148  *	pattern(s) (no patterns extracts all members)
149  */
150 
151 void
152 extract(void)
153 {
154 	ARCHD *arcn;
155 	int res;
156 	off_t cnt;
157 	ARCHD archd;
158 	struct stat sb;
159 	int fd;
160 	time_t now;
161 
162 	arcn = &archd;
163 	/*
164 	 * figure out archive type; pass any format specific options to the
165 	 * archive option processing routine; call the format init routine;
166 	 * start up the directory modification time and access mode database
167 	 */
168 	if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
169 	    ((*frmt->st_rd)() < 0) || (dir_start() < 0))
170 		return;
171 
172 	/*
173 	 * When we are doing interactive rename, we store the mapping of names
174 	 * so we can fix up hard links files later in the archive.
175 	 */
176 	if (iflag && (name_start() < 0))
177 		return;
178 
179 	now = time(NULL);
180 
181 	/*
182 	 * step through each entry on the archive until the format read routine
183 	 * says it is done
184 	 */
185 	while (next_head(arcn) == 0) {
186 
187 		/*
188 		 * check for pattern, and user specified options match. When
189 		 * all the patterns are matched we are done
190 		 */
191 		if ((res = pat_match(arcn)) < 0)
192 			break;
193 
194 		if ((res > 0) || (sel_chk(arcn) != 0)) {
195 			/*
196 			 * file is not selected. skip past any file data and
197 			 * padding and go back for the next archive member
198 			 */
199 			(void)rd_skip(arcn->skip + arcn->pad);
200 			continue;
201 		}
202 
203 		/*
204 		 * with -u or -D only extract when the archive member is newer
205 		 * than the file with the same name in the file system (nos
206 		 * test of being the same type is required).
207 		 * NOTE: this test is done BEFORE name modifications as
208 		 * specified by pax. this operation can be confusing to the
209 		 * user who might expect the test to be done on an existing
210 		 * file AFTER the name mod. In honesty the pax spec is probably
211 		 * flawed in this respect.
212 		 */
213 		if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
214 			if (uflag && Dflag) {
215 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
216 				    (arcn->sb.st_ctime <= sb.st_ctime)) {
217 					(void)rd_skip(arcn->skip + arcn->pad);
218 					continue;
219 				}
220 			} else if (Dflag) {
221 				if (arcn->sb.st_ctime <= sb.st_ctime) {
222 					(void)rd_skip(arcn->skip + arcn->pad);
223 					continue;
224 				}
225 			} else if (arcn->sb.st_mtime <= sb.st_mtime) {
226 				(void)rd_skip(arcn->skip + arcn->pad);
227 				continue;
228 			}
229 		}
230 
231 		/*
232 		 * this archive member is now been selected. modify the name.
233 		 */
234 		if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
235 			break;
236 		if (res > 0) {
237 			/*
238 			 * a bad name mod, skip and purge name from link table
239 			 */
240 			purg_lnk(arcn);
241 			(void)rd_skip(arcn->skip + arcn->pad);
242 			continue;
243 		}
244 
245 		/*
246 		 * Non standard -Y and -Z flag. When the existing file is
247 		 * same age or newer skip
248 		 */
249 		if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
250 			if (Yflag && Zflag) {
251 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
252 				    (arcn->sb.st_ctime <= sb.st_ctime)) {
253 					(void)rd_skip(arcn->skip + arcn->pad);
254 					continue;
255 				}
256 			} else if (Yflag) {
257 				if (arcn->sb.st_ctime <= sb.st_ctime) {
258 					(void)rd_skip(arcn->skip + arcn->pad);
259 					continue;
260 				}
261 			} else if (arcn->sb.st_mtime <= sb.st_mtime) {
262 				(void)rd_skip(arcn->skip + arcn->pad);
263 				continue;
264 			}
265 		}
266 
267 		if (vflag) {
268 			if (vflag > 1)
269 				ls_list(arcn, now, listf);
270 			else {
271 				(void)fputs(arcn->name, listf);
272 				vfpart = 1;
273 			}
274 		}
275 
276 		/*
277 		 * if required, chdir around.
278 		 */
279 		if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
280 			if (chdir(arcn->pat->chdname) != 0)
281 				syswarn(1, errno, "Cannot chdir to %s",
282 				    arcn->pat->chdname);
283 
284 		/*
285 		 * all ok, extract this member based on type
286 		 */
287 		if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
288 			/*
289 			 * process archive members that are not regular files.
290 			 * throw out padding and any data that might follow the
291 			 * header (as determined by the format).
292 			 */
293 			if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
294 				res = lnk_creat(arcn);
295 			else
296 				res = node_creat(arcn);
297 
298 			(void)rd_skip(arcn->skip + arcn->pad);
299 			if (res < 0)
300 				purg_lnk(arcn);
301 
302 			if (vflag && vfpart) {
303 				(void)putc('\n', listf);
304 				vfpart = 0;
305 			}
306 			continue;
307 		}
308 		/*
309 		 * we have a file with data here. If we can not create it, skip
310 		 * over the data and purge the name from hard link table
311 		 */
312 		if ((fd = file_creat(arcn)) < 0) {
313 			(void)rd_skip(arcn->skip + arcn->pad);
314 			purg_lnk(arcn);
315 			continue;
316 		}
317 		/*
318 		 * extract the file from the archive and skip over padding and
319 		 * any unprocessed data
320 		 */
321 		res = (*frmt->rd_data)(arcn, fd, &cnt);
322 		file_close(arcn, fd);
323 		if (vflag && vfpart) {
324 			(void)putc('\n', listf);
325 			vfpart = 0;
326 		}
327 		if (!res)
328 			(void)rd_skip(cnt + arcn->pad);
329 
330 		/*
331 		 * if required, chdir around.
332 		 */
333 		if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
334 			if (fchdir(cwdfd) != 0)
335 				syswarn(1, errno,
336 				    "Can't fchdir to starting directory");
337 	}
338 
339 	/*
340 	 * all done, restore directory modes and times as required; make sure
341 	 * all patterns supplied by the user were matched; block off signals
342 	 * to avoid chance for multiple entry into the cleanup code.
343 	 */
344 	(void)(*frmt->end_rd)();
345 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
346 	ar_close();
347 	proc_dir();
348 	pat_chk();
349 }
350 
351 /*
352  * wr_archive()
353  *	Write an archive. used in both creating a new archive and appends on
354  *	previously written archive.
355  */
356 
357 static void
358 wr_archive(ARCHD *arcn, int is_app)
359 {
360 	int res;
361 	int hlk;
362 	int wr_one;
363 	off_t cnt;
364 	int (*wrf)(ARCHD *);
365 	int fd = -1;
366 	time_t now;
367 
368 	/*
369 	 * if this format supports hard link storage, start up the database
370 	 * that detects them.
371 	 */
372 	if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
373 		return;
374 
375 	/*
376 	 * start up the file traversal code and format specific write
377 	 */
378 	if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
379 		return;
380 	wrf = frmt->wr;
381 
382 	/*
383 	 * When we are doing interactive rename, we store the mapping of names
384 	 * so we can fix up hard links files later in the archive.
385 	 */
386 	if (iflag && (name_start() < 0))
387 		return;
388 
389 	/*
390 	 * if this not append, and there are no files, we do no write a trailer
391 	 */
392 	wr_one = is_app;
393 
394 	now = time(NULL);
395 
396 	/*
397 	 * while there are files to archive, process them one at at time
398 	 */
399 	while (next_file(arcn) == 0) {
400 		/*
401 		 * check if this file meets user specified options match.
402 		 */
403 		if (sel_chk(arcn) != 0) {
404 			ftree_notsel();
405 			continue;
406 		}
407 		fd = -1;
408 		if (uflag) {
409 			/*
410 			 * only archive if this file is newer than a file with
411 			 * the same name that is already stored on the archive
412 			 */
413 			if ((res = chk_ftime(arcn)) < 0)
414 				break;
415 			if (res > 0)
416 				continue;
417 		}
418 
419 		/*
420 		 * this file is considered selected now. see if this is a hard
421 		 * link to a file already stored
422 		 */
423 		ftree_sel(arcn);
424 		if (hlk && (chk_lnk(arcn) < 0))
425 			break;
426 
427 		if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
428 		    (arcn->type == PAX_CTG)) {
429 			/*
430 			 * we will have to read this file. by opening it now we
431 			 * can avoid writing a header to the archive for a file
432 			 * we were later unable to read (we also purge it from
433 			 * the link table).
434 			 */
435 			if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
436 				syswarn(1,errno, "Unable to open %s to read",
437 					arcn->org_name);
438 				purg_lnk(arcn);
439 				continue;
440 			}
441 		}
442 
443 		/*
444 		 * Now modify the name as requested by the user
445 		 */
446 		if ((res = mod_name(arcn)) < 0) {
447 			/*
448 			 * name modification says to skip this file, close the
449 			 * file and purge link table entry
450 			 */
451 			rdfile_close(arcn, &fd);
452 			purg_lnk(arcn);
453 			break;
454 		}
455 
456 		if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
457 			/*
458 			 * unable to obtain the crc we need, close the file,
459 			 * purge link table entry
460 			 */
461 			rdfile_close(arcn, &fd);
462 			purg_lnk(arcn);
463 			continue;
464 		}
465 
466 		if (vflag) {
467 			if (vflag > 1)
468 				ls_list(arcn, now, listf);
469 			else {
470 				(void)fputs(arcn->name, listf);
471 				vfpart = 1;
472 			}
473 		}
474 		++flcnt;
475 
476 		/*
477 		 * looks safe to store the file, have the format specific
478 		 * routine write routine store the file header on the archive
479 		 */
480 		if ((res = (*wrf)(arcn)) < 0) {
481 			rdfile_close(arcn, &fd);
482 			break;
483 		}
484 		wr_one = 1;
485 		if (res > 0) {
486 			/*
487 			 * format write says no file data needs to be stored
488 			 * so we are done messing with this file
489 			 */
490 			if (vflag && vfpart) {
491 				(void)putc('\n', listf);
492 				vfpart = 0;
493 			}
494 			rdfile_close(arcn, &fd);
495 			continue;
496 		}
497 
498 		/*
499 		 * Add file data to the archive, quit on write error. if we
500 		 * cannot write the entire file contents to the archive we
501 		 * must pad the archive to replace the missing file data
502 		 * (otherwise during an extract the file header for the file
503 		 * which FOLLOWS this one will not be where we expect it to
504 		 * be).
505 		 */
506 		res = (*frmt->wr_data)(arcn, fd, &cnt);
507 		rdfile_close(arcn, &fd);
508 		if (vflag && vfpart) {
509 			(void)putc('\n', listf);
510 			vfpart = 0;
511 		}
512 		if (res < 0)
513 			break;
514 
515 		/*
516 		 * pad as required, cnt is number of bytes not written
517 		 */
518 		if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
519 		    ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
520 			break;
521 	}
522 
523 	/*
524 	 * tell format to write trailer; pad to block boundary; reset directory
525 	 * mode/access times, and check if all patterns supplied by the user
526 	 * were matched. block off signals to avoid chance for multiple entry
527 	 * into the cleanup code
528 	 */
529 	if (wr_one) {
530 		(*frmt->end_wr)();
531 		wr_fin();
532 	}
533 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
534 	ar_close();
535 	if (tflag)
536 		proc_dir();
537 	ftree_chk();
538 }
539 
540 /*
541  * append()
542  *	Add file to previously written archive. Archive format specified by the
543  *	user must agree with archive. The archive is read first to collect
544  *	modification times (if -u) and locate the archive trailer. The archive
545  *	is positioned in front of the record with the trailer and wr_archive()
546  *	is called to add the new members.
547  *	PAX IMPLEMENTATION DETAIL NOTE:
548  *	-u is implemented by adding the new members to the end of the archive.
549  *	Care is taken so that these do not end up as links to the older
550  *	version of the same file already stored in the archive. It is expected
551  *	when extraction occurs these newer versions will over-write the older
552  *	ones stored "earlier" in the archive (this may be a bad assumption as
553  *	it depends on the implementation of the program doing the extraction).
554  *	It is really difficult to splice in members without either re-writing
555  *	the entire archive (from the point were the old version was), or having
556  *	assistance of the format specification in terms of a special update
557  *	header that invalidates a previous archive record. The POSIX spec left
558  *	the method used to implement -u unspecified. This pax is able to
559  *	over write existing files that it creates.
560  */
561 
562 void
563 append(void)
564 {
565 	ARCHD *arcn;
566 	int res;
567 	ARCHD archd;
568 	FSUB *orgfrmt;
569 	int udev;
570 	off_t tlen;
571 
572 	arcn = &archd;
573 	orgfrmt = frmt;
574 
575 	/*
576 	 * Do not allow an append operation if the actual archive is of a
577 	 * different format than the user specified format.
578 	 */
579 	if (get_arc() < 0)
580 		return;
581 	if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
582 		paxwarn(1, "Cannot mix current archive format %s with %s",
583 		    frmt->name, orgfrmt->name);
584 		return;
585 	}
586 
587 	/*
588 	 * pass the format any options and start up format
589 	 */
590 	if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
591 		return;
592 
593 	/*
594 	 * if we only are adding members that are newer, we need to save the
595 	 * mod times for all files we see.
596 	 */
597 	if (uflag && (ftime_start() < 0))
598 		return;
599 
600 	/*
601 	 * some archive formats encode hard links by recording the device and
602 	 * file serial number (inode) but copy the file anyway (multiple times)
603 	 * to the archive. When we append, we run the risk that newly added
604 	 * files may have the same device and inode numbers as those recorded
605 	 * on the archive but during a previous run. If this happens, when the
606 	 * archive is extracted we get INCORRECT hard links. We avoid this by
607 	 * remapping the device numbers so that newly added files will never
608 	 * use the same device number as one found on the archive. remapping
609 	 * allows new members to safely have links among themselves. remapping
610 	 * also avoids problems with file inode (serial number) truncations
611 	 * when the inode number is larger than storage space in the archive
612 	 * header. See the remap routines for more details.
613 	 */
614 	if ((udev = frmt->udev) && (dev_start() < 0))
615 		return;
616 
617 	/*
618 	 * reading the archive may take a long time. If verbose tell the user
619 	 */
620 	if (vflag) {
621 		(void)fprintf(listf,
622 			"%s: Reading archive to position at the end...", argv0);
623 		vfpart = 1;
624 	}
625 
626 	/*
627 	 * step through the archive until the format says it is done
628 	 */
629 	while (next_head(arcn) == 0) {
630 		/*
631 		 * check if this file meets user specified options.
632 		 */
633 		if (sel_chk(arcn) != 0) {
634 			if (rd_skip(arcn->skip + arcn->pad) == 1)
635 				break;
636 			continue;
637 		}
638 
639 		if (uflag) {
640 			/*
641 			 * see if this is the newest version of this file has
642 			 * already been seen, if so skip.
643 			 */
644 			if ((res = chk_ftime(arcn)) < 0)
645 				break;
646 			if (res > 0) {
647 				if (rd_skip(arcn->skip + arcn->pad) == 1)
648 					break;
649 				continue;
650 			}
651 		}
652 
653 		/*
654 		 * Store this device number. Device numbers seen during the
655 		 * read phase of append will cause newly appended files with a
656 		 * device number seen in the old part of the archive to be
657 		 * remapped to an unused device number.
658 		 */
659 		if ((udev && (add_dev(arcn) < 0)) ||
660 		    (rd_skip(arcn->skip + arcn->pad) == 1))
661 			break;
662 	}
663 
664 	/*
665 	 * done, finish up read and get the number of bytes to back up so we
666 	 * can add new members. The format might have used the hard link table,
667 	 * purge it.
668 	 */
669 	tlen = (*frmt->end_rd)();
670 	lnk_end();
671 
672 	/*
673 	 * try to position for write, if this fails quit. if any error occurs,
674 	 * we will refuse to write
675 	 */
676 	if (appnd_start(tlen) < 0)
677 		return;
678 
679 	/*
680 	 * tell the user we are done reading.
681 	 */
682 	if (vflag && vfpart) {
683 		(void)fputs("done.\n", listf);
684 		vfpart = 0;
685 	}
686 
687 	/*
688 	 * go to the writing phase to add the new members
689 	 */
690 	wr_archive(arcn, 1);
691 }
692 
693 /*
694  * archive()
695  *	write a new archive
696  */
697 
698 void
699 archive(void)
700 {
701 	ARCHD archd;
702 
703 	/*
704 	 * if we only are adding members that are newer, we need to save the
705 	 * mod times for all files; set up for writing; pass the format any
706 	 * options write the archive
707 	 */
708 	if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
709 		return;
710 	if ((*frmt->options)() < 0)
711 		return;
712 
713 	wr_archive(&archd, 0);
714 }
715 
716 /*
717  * copy()
718  *	copy files from one part of the file system to another. this does not
719  *	use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
720  *	archive was written and then extracted in the destination directory
721  *	(except the files are forced to be under the destination directory).
722  */
723 
724 void
725 copy(void)
726 {
727 	ARCHD *arcn;
728 	int res;
729 	int fddest;
730 	char *dest_pt;
731 	int dlen;
732 	int drem;
733 	int fdsrc = -1;
734 	struct stat sb;
735 	ARCHD archd;
736 	char dirbuf[PAXPATHLEN+1];
737 
738 	arcn = &archd;
739 	/*
740 	 * set up the destination dir path and make sure it is a directory. We
741 	 * make sure we have a trailing / on the destination
742 	 */
743 	dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
744 	dest_pt = dirbuf + dlen;
745 	if (*(dest_pt-1) != '/') {
746 		*dest_pt++ = '/';
747 		++dlen;
748 	}
749 	*dest_pt = '\0';
750 	drem = PAXPATHLEN - dlen;
751 
752 	if (stat(dirptr, &sb) < 0) {
753 		syswarn(1, errno, "Cannot access destination directory %s",
754 			dirptr);
755 		return;
756 	}
757 	if (!S_ISDIR(sb.st_mode)) {
758 		paxwarn(1, "Destination is not a directory %s", dirptr);
759 		return;
760 	}
761 
762 	/*
763 	 * start up the hard link table; file traversal routines and the
764 	 * modification time and access mode database
765 	 */
766 	if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
767 		return;
768 
769 	/*
770 	 * When we are doing interactive rename, we store the mapping of names
771 	 * so we can fix up hard links files later in the archive.
772 	 */
773 	if (iflag && (name_start() < 0))
774 		return;
775 
776 	/*
777 	 * set up to cp file trees
778 	 */
779 	cp_start();
780 
781 	/*
782 	 * while there are files to archive, process them
783 	 */
784 	while (next_file(arcn) == 0) {
785 		fdsrc = -1;
786 
787 		/*
788 		 * check if this file meets user specified options
789 		 */
790 		if (sel_chk(arcn) != 0) {
791 			ftree_notsel();
792 			continue;
793 		}
794 
795 		/*
796 		 * if there is already a file in the destination directory with
797 		 * the same name and it is newer, skip the one stored on the
798 		 * archive.
799 		 * NOTE: this test is done BEFORE name modifications as
800 		 * specified by pax. this can be confusing to the user who
801 		 * might expect the test to be done on an existing file AFTER
802 		 * the name mod. In honesty the pax spec is probably flawed in
803 		 * this respect
804 		 */
805 		if (uflag || Dflag) {
806 			/*
807 			 * create the destination name
808 			 */
809 			if (*(arcn->name) == '/')
810 				res = 1;
811 			else
812 				res = 0;
813 			if ((arcn->nlen - res) > drem) {
814 				paxwarn(1, "Destination pathname too long %s",
815 					arcn->name);
816 				continue;
817 			}
818 			(void)strncpy(dest_pt, arcn->name + res, drem);
819 			dirbuf[PAXPATHLEN] = '\0';
820 
821 			/*
822 			 * if existing file is same age or newer skip
823 			 */
824 			res = lstat(dirbuf, &sb);
825 			*dest_pt = '\0';
826 
827 		    	if (res == 0) {
828 				if (uflag && Dflag) {
829 					if ((arcn->sb.st_mtime<=sb.st_mtime) &&
830 			    		    (arcn->sb.st_ctime<=sb.st_ctime))
831 						continue;
832 				} else if (Dflag) {
833 					if (arcn->sb.st_ctime <= sb.st_ctime)
834 						continue;
835 				} else if (arcn->sb.st_mtime <= sb.st_mtime)
836 					continue;
837 			}
838 		}
839 
840 		/*
841 		 * this file is considered selected. See if this is a hard link
842 		 * to a previous file; modify the name as requested by the
843 		 * user; set the final destination.
844 		 */
845 		ftree_sel(arcn);
846 		if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
847 			break;
848 		if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
849 			/*
850 			 * skip file, purge from link table
851 			 */
852 			purg_lnk(arcn);
853 			continue;
854 		}
855 
856 		/*
857 		 * Non standard -Y and -Z flag. When the existing file is
858 		 * same age or newer skip
859 		 */
860 		if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
861 			if (Yflag && Zflag) {
862 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
863 				    (arcn->sb.st_ctime <= sb.st_ctime))
864 					continue;
865 			} else if (Yflag) {
866 				if (arcn->sb.st_ctime <= sb.st_ctime)
867 					continue;
868 			} else if (arcn->sb.st_mtime <= sb.st_mtime)
869 				continue;
870 		}
871 
872 		if (vflag) {
873 			(void)fputs(arcn->name, listf);
874 			vfpart = 1;
875 		}
876 		++flcnt;
877 
878 		/*
879 		 * try to create a hard link to the src file if requested
880 		 * but make sure we are not trying to overwrite ourselves.
881 		 */
882 		if (lflag)
883 			res = cross_lnk(arcn);
884 		else
885 			res = chk_same(arcn);
886 		if (res <= 0) {
887 			if (vflag && vfpart) {
888 				(void)putc('\n', listf);
889 				vfpart = 0;
890 			}
891 			continue;
892 		}
893 
894 		/*
895 		 * have to create a new file
896 		 */
897 		if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
898 			/*
899 			 * create a link or special file
900 			 */
901 			if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
902 				res = lnk_creat(arcn);
903 			else
904 				res = node_creat(arcn);
905 			if (res < 0)
906 				purg_lnk(arcn);
907 			if (vflag && vfpart) {
908 				(void)putc('\n', listf);
909 				vfpart = 0;
910 			}
911 			continue;
912 		}
913 
914 		/*
915 		 * have to copy a regular file to the destination directory.
916 		 * first open source file and then create the destination file
917 		 */
918 		if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
919 			syswarn(1, errno, "Unable to open %s to read",
920 			    arcn->org_name);
921 			purg_lnk(arcn);
922 			continue;
923 		}
924 		if ((fddest = file_creat(arcn)) < 0) {
925 			rdfile_close(arcn, &fdsrc);
926 			purg_lnk(arcn);
927 			continue;
928 		}
929 
930 		/*
931 		 * copy source file data to the destination file
932 		 */
933 		cp_file(arcn, fdsrc, fddest);
934 		file_close(arcn, fddest);
935 		rdfile_close(arcn, &fdsrc);
936 
937 		if (vflag && vfpart) {
938 			(void)putc('\n', listf);
939 			vfpart = 0;
940 		}
941 	}
942 
943 	/*
944 	 * restore directory modes and times as required; make sure all
945 	 * patterns were selected block off signals to avoid chance for
946 	 * multiple entry into the cleanup code.
947 	 */
948 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
949 	ar_close();
950 	proc_dir();
951 	ftree_chk();
952 }
953 
954 /*
955  * next_head()
956  *	try to find a valid header in the archive. Uses format specific
957  *	routines to extract the header and id the trailer. Trailers may be
958  *	located within a valid header or in an invalid header (the location
959  *	is format specific. The inhead field from the option table tells us
960  *	where to look for the trailer).
961  *	We keep reading (and resyncing) until we get enough contiguous data
962  *	to check for a header. If we cannot find one, we shift by a byte
963  *	add a new byte from the archive to the end of the buffer and try again.
964  *	If we get a read error, we throw out what we have (as we must have
965  *	contiguous data) and start over again.
966  *	ASSUMED: headers fit within a BLKMULT header.
967  * Return:
968  *	0 if we got a header, -1 if we are unable to ever find another one
969  *	(we reached the end of input, or we reached the limit on retries. see
970  *	the specs for rd_wrbuf() for more details)
971  */
972 
973 static int
974 next_head(ARCHD *arcn)
975 {
976 	int ret;
977 	char *hdend;
978 	int res;
979 	int shftsz;
980 	int hsz;
981 	int in_resync = 0; 	/* set when we are in resync mode */
982 	int cnt = 0;			/* counter for trailer function */
983 	int first = 1;			/* on 1st read, EOF isn't premature. */
984 
985 	/*
986 	 * set up initial conditions, we want a whole frmt->hsz block as we
987 	 * have no data yet.
988 	 */
989 	res = hsz = frmt->hsz;
990 	hdend = hdbuf;
991 	shftsz = hsz - 1;
992 	for(;;) {
993 		/*
994 		 * keep looping until we get a contiguous FULL buffer
995 		 * (frmt->hsz is the proper size)
996 		 */
997 		for (;;) {
998 			if ((ret = rd_wrbuf(hdend, res)) == res)
999 				break;
1000 
1001 			/*
1002 			 * If we read 0 bytes (EOF) from an archive when we
1003 			 * expect to find a header, we have stepped upon
1004 			 * an archive without the customary block of zeroes
1005 			 * end marker.  It's just stupid to error out on
1006 			 * them, so exit gracefully.
1007 			 */
1008 			if (first && ret == 0)
1009 				return(-1);
1010 			first = 0;
1011 
1012 			/*
1013 			 * some kind of archive read problem, try to resync the
1014 			 * storage device, better give the user the bad news.
1015 			 */
1016 			if ((ret == 0) || (rd_sync() < 0)) {
1017 				paxwarn(1,"Premature end of file on archive read");
1018 				return(-1);
1019 			}
1020 			if (!in_resync) {
1021 				if (act == APPND) {
1022 					paxwarn(1,
1023 					  "Archive I/O error, cannot continue");
1024 					return(-1);
1025 				}
1026 				paxwarn(1,"Archive I/O error. Trying to recover.");
1027 				++in_resync;
1028 			}
1029 
1030 			/*
1031 			 * oh well, throw it all out and start over
1032 			 */
1033 			res = hsz;
1034 			hdend = hdbuf;
1035 		}
1036 
1037 		/*
1038 		 * ok we have a contiguous buffer of the right size. Call the
1039 		 * format read routine. If this was not a valid header and this
1040 		 * format stores trailers outside of the header, call the
1041 		 * format specific trailer routine to check for a trailer. We
1042 		 * have to watch out that we do not mis-identify file data or
1043 		 * block padding as a header or trailer. Format specific
1044 		 * trailer functions must NOT check for the trailer while we
1045 		 * are running in resync mode. Some trailer functions may tell
1046 		 * us that this block cannot contain a valid header either, so
1047 		 * we then throw out the entire block and start over.
1048 		 */
1049 		if ((*frmt->rd)(arcn, hdbuf) == 0)
1050 			break;
1051 
1052 		if (!frmt->inhead) {
1053 			/*
1054 			 * this format has trailers outside of valid headers
1055 			 */
1056 			if ((ret = (*frmt->trail_tar)(hdbuf,in_resync,&cnt)) == 0){
1057 				/*
1058 				 * valid trailer found, drain input as required
1059 				 */
1060 				ar_drain();
1061 				return(-1);
1062 			}
1063 
1064 			if (ret == 1) {
1065 				/*
1066 				 * we are in resync and we were told to throw
1067 				 * the whole block out because none of the
1068 				 * bytes in this block can be used to form a
1069 				 * valid header
1070 				 */
1071 				res = hsz;
1072 				hdend = hdbuf;
1073 				continue;
1074 			}
1075 		}
1076 
1077 		/*
1078 		 * Brute force section.
1079 		 * not a valid header. We may be able to find a header yet. So
1080 		 * we shift over by one byte, and set up to read one byte at a
1081 		 * time from the archive and place it at the end of the buffer.
1082 		 * We will keep moving byte at a time until we find a header or
1083 		 * get a read error and have to start over.
1084 		 */
1085 		if (!in_resync) {
1086 			if (act == APPND) {
1087 				paxwarn(1,"Unable to append, archive header flaw");
1088 				return(-1);
1089 			}
1090 			paxwarn(1,"Invalid header, starting valid header search.");
1091 			++in_resync;
1092 		}
1093 		memmove(hdbuf, hdbuf+1, shftsz);
1094 		res = 1;
1095 		hdend = hdbuf + shftsz;
1096 	}
1097 
1098 	/*
1099 	 * ok got a valid header, check for trailer if format encodes it in
1100 	 * the header.
1101 	 */
1102 	if (frmt->inhead && ((*frmt->trail_cpio)(arcn) == 0)) {
1103 		/*
1104 		 * valid trailer found, drain input as required
1105 		 */
1106 		ar_drain();
1107 		return(-1);
1108 	}
1109 
1110 	++flcnt;
1111 	return(0);
1112 }
1113 
1114 /*
1115  * get_arc()
1116  *	Figure out what format an archive is. Handles archive with flaws by
1117  *	brute force searches for a legal header in any supported format. The
1118  *	format id routines have to be careful to NOT mis-identify a format.
1119  *	ASSUMED: headers fit within a BLKMULT header.
1120  * Return:
1121  *	0 if archive found -1 otherwise
1122  */
1123 
1124 static int
1125 get_arc(void)
1126 {
1127 	int i;
1128 	int hdsz = 0;
1129 	int res;
1130 	int minhd = BLKMULT;
1131 	char *hdend;
1132 	int notice = 0;
1133 
1134 	/*
1135 	 * find the smallest header size in all archive formats and then set up
1136 	 * to read the archive.
1137 	 */
1138 	for (i = 0; ford[i] >= 0; ++i) {
1139 		if (fsub[ford[i]].hsz < minhd)
1140 			minhd = fsub[ford[i]].hsz;
1141 	}
1142 	if (rd_start() < 0)
1143 		return(-1);
1144 	res = BLKMULT;
1145 	hdsz = 0;
1146 	hdend = hdbuf;
1147 	for(;;) {
1148 		for (;;) {
1149 			/*
1150 			 * fill the buffer with at least the smallest header
1151 			 */
1152 			i = rd_wrbuf(hdend, res);
1153 			if (i > 0)
1154 				hdsz += i;
1155 			if (hdsz >= minhd)
1156 				break;
1157 
1158 			/*
1159 			 * if we cannot recover from a read error quit
1160 			 */
1161 			if ((i == 0) || (rd_sync() < 0))
1162 				goto out;
1163 
1164 			/*
1165 			 * when we get an error none of the data we already
1166 			 * have can be used to create a legal header (we just
1167 			 * got an error in the middle), so we throw it all out
1168 			 * and refill the buffer with fresh data.
1169 			 */
1170 			res = BLKMULT;
1171 			hdsz = 0;
1172 			hdend = hdbuf;
1173 			if (!notice) {
1174 				if (act == APPND)
1175 					return(-1);
1176 				paxwarn(1,"Cannot identify format. Searching...");
1177 				++notice;
1178 			}
1179 		}
1180 
1181 		/*
1182 		 * we have at least the size of the smallest header in any
1183 		 * archive format. Look to see if we have a match. The array
1184 		 * ford[] is used to specify the header id order to reduce the
1185 		 * chance of incorrectly id'ing a valid header (some formats
1186 		 * may be subsets of each other and the order would then be
1187 		 * important).
1188 		 */
1189 		for (i = 0; ford[i] >= 0; ++i) {
1190 			if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
1191 				continue;
1192 			frmt = &(fsub[ford[i]]);
1193 			/*
1194 			 * yuck, to avoid slow special case code in the extract
1195 			 * routines, just push this header back as if it was
1196 			 * not seen. We have left extra space at start of the
1197 			 * buffer for this purpose. This is a bit ugly, but
1198 			 * adding all the special case code is far worse.
1199 			 */
1200 			pback(hdbuf, hdsz);
1201 			return(0);
1202 		}
1203 
1204 		/*
1205 		 * We have a flawed archive, no match. we start searching, but
1206 		 * we never allow additions to flawed archives
1207 		 */
1208 		if (!notice) {
1209 			if (act == APPND)
1210 				return(-1);
1211 			paxwarn(1, "Cannot identify format. Searching...");
1212 			++notice;
1213 		}
1214 
1215 		/*
1216 		 * brute force search for a header that we can id.
1217 		 * we shift through byte at a time. this is slow, but we cannot
1218 		 * determine the nature of the flaw in the archive in a
1219 		 * portable manner
1220 		 */
1221 		if (--hdsz > 0) {
1222 			memmove(hdbuf, hdbuf+1, hdsz);
1223 			res = BLKMULT - hdsz;
1224 			hdend = hdbuf + hdsz;
1225 		} else {
1226 			res = BLKMULT;
1227 			hdend = hdbuf;
1228 			hdsz = 0;
1229 		}
1230 	}
1231 
1232     out:
1233 	/*
1234 	 * we cannot find a header, bow, apologize and quit
1235 	 */
1236 	paxwarn(1, "Sorry, unable to determine archive format.");
1237 	return(-1);
1238 }
1239