xref: /freebsd/bin/pax/ar_subs.c (revision 90aac0d83bc9645f51ef0c2aeae6f9c0540bb031)
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 #include <sys/types.h>
43 #include <sys/time.h>
44 #include <sys/stat.h>
45 #include <signal.h>
46 #include <string.h>
47 #include <stdio.h>
48 #include <fcntl.h>
49 #include <errno.h>
50 #include <unistd.h>
51 #include "pax.h"
52 #include "extern.h"
53 
54 static void wr_archive(ARCHD *, int is_app);
55 static int get_arc(void);
56 static int next_head(ARCHD *);
57 
58 /*
59  * Routines which control the overall operation modes of pax as specified by
60  * the user: list, append, read ...
61  */
62 
63 static char hdbuf[BLKMULT];		/* space for archive header on read */
64 u_long flcnt;				/* number of files processed */
65 
66 /*
67  * list()
68  *	list the contents of an archive which match user supplied pattern(s)
69  *	(no pattern matches all).
70  */
71 
72 void
73 list(void)
74 {
75 	ARCHD *arcn;
76 	int res;
77 	ARCHD archd;
78 	time_t now;
79 
80 	arcn = &archd;
81 	/*
82 	 * figure out archive type; pass any format specific options to the
83 	 * archive option processing routine; call the format init routine. We
84 	 * also save current time for ls_list() so we do not make a system
85 	 * call for each file we need to print. If verbose (vflag) start up
86 	 * the name and group caches.
87 	 */
88 	if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
89 	    ((*frmt->st_rd)() < 0))
90 		return;
91 
92 	if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
93 		return;
94 
95 	now = time(NULL);
96 
97 	/*
98 	 * step through the archive until the format says it is done
99 	 */
100 	while (next_head(arcn) == 0) {
101 		/*
102 		 * check for pattern, and user specified options match.
103 		 * When all patterns are matched we are done.
104 		 */
105 		if ((res = pat_match(arcn)) < 0)
106 			break;
107 
108 		if ((res == 0) && (sel_chk(arcn) == 0)) {
109 			/*
110 			 * pattern resulted in a selected file
111 			 */
112 			if (pat_sel(arcn) < 0)
113 				break;
114 
115 			/*
116 			 * modify the name as requested by the user if name
117 			 * survives modification, do a listing of the file
118 			 */
119 			if ((res = mod_name(arcn)) < 0)
120 				break;
121 			if (res == 0)
122 				ls_list(arcn, now, stdout);
123 		}
124 
125 		/*
126 		 * skip to next archive format header using values calculated
127 		 * by the format header read routine
128 		 */
129 		if (rd_skip(arcn->skip + arcn->pad) == 1)
130 			break;
131 	}
132 
133 	/*
134 	 * all done, let format have a chance to cleanup, and make sure that
135 	 * the patterns supplied by the user were all matched
136 	 */
137 	(void)(*frmt->end_rd)();
138 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
139 	ar_close();
140 	pat_chk();
141 }
142 
143 /*
144  * extract()
145  *	extract the member(s) of an archive as specified by user supplied
146  *	pattern(s) (no patterns extracts all members)
147  */
148 
149 void
150 extract(void)
151 {
152 	ARCHD *arcn;
153 	int res;
154 	off_t cnt;
155 	ARCHD archd;
156 	struct stat sb;
157 	int fd;
158 	time_t now;
159 
160 	arcn = &archd;
161 	/*
162 	 * figure out archive type; pass any format specific options to the
163 	 * archive option processing routine; call the format init routine;
164 	 * start up the directory modification time and access mode database
165 	 */
166 	if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
167 	    ((*frmt->st_rd)() < 0) || (dir_start() < 0))
168 		return;
169 
170 	/*
171 	 * When we are doing interactive rename, we store the mapping of names
172 	 * so we can fix up hard links files later in the archive.
173 	 */
174 	if (iflag && (name_start() < 0))
175 		return;
176 
177 	now = time(NULL);
178 
179 	/*
180 	 * step through each entry on the archive until the format read routine
181 	 * says it is done
182 	 */
183 	while (next_head(arcn) == 0) {
184 
185 		/*
186 		 * check for pattern, and user specified options match. When
187 		 * all the patterns are matched we are done
188 		 */
189 		if ((res = pat_match(arcn)) < 0)
190 			break;
191 
192 		if ((res > 0) || (sel_chk(arcn) != 0)) {
193 			/*
194 			 * file is not selected. skip past any file data and
195 			 * padding and go back for the next archive member
196 			 */
197 			(void)rd_skip(arcn->skip + arcn->pad);
198 			continue;
199 		}
200 
201 		/*
202 		 * with -u or -D only extract when the archive member is newer
203 		 * than the file with the same name in the file system (no
204 		 * test of being the same type is required).
205 		 * NOTE: this test is done BEFORE name modifications as
206 		 * specified by pax. this operation can be confusing to the
207 		 * user who might expect the test to be done on an existing
208 		 * file AFTER the name mod. In honesty the pax spec is probably
209 		 * flawed in this respect.
210 		 */
211 		if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
212 			if (uflag && Dflag) {
213 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
214 				    (arcn->sb.st_ctime <= sb.st_ctime)) {
215 					(void)rd_skip(arcn->skip + arcn->pad);
216 					continue;
217 				}
218 			} else if (Dflag) {
219 				if (arcn->sb.st_ctime <= sb.st_ctime) {
220 					(void)rd_skip(arcn->skip + arcn->pad);
221 					continue;
222 				}
223 			} else if (arcn->sb.st_mtime <= sb.st_mtime) {
224 				(void)rd_skip(arcn->skip + arcn->pad);
225 				continue;
226 			}
227 		}
228 
229 		/*
230 		 * this archive member is now been selected. modify the name.
231 		 */
232 		if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
233 			break;
234 		if (res > 0) {
235 			/*
236 			 * a bad name mod, skip and purge name from link table
237 			 */
238 			purg_lnk(arcn);
239 			(void)rd_skip(arcn->skip + arcn->pad);
240 			continue;
241 		}
242 
243 		/*
244 		 * Non standard -Y and -Z flag. When the existing file is
245 		 * same age or newer skip
246 		 */
247 		if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
248 			if (Yflag && Zflag) {
249 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
250 				    (arcn->sb.st_ctime <= sb.st_ctime)) {
251 					(void)rd_skip(arcn->skip + arcn->pad);
252 					continue;
253 				}
254 			} else if (Yflag) {
255 				if (arcn->sb.st_ctime <= sb.st_ctime) {
256 					(void)rd_skip(arcn->skip + arcn->pad);
257 					continue;
258 				}
259 			} else if (arcn->sb.st_mtime <= sb.st_mtime) {
260 				(void)rd_skip(arcn->skip + arcn->pad);
261 				continue;
262 			}
263 		}
264 
265 		if (vflag) {
266 			if (vflag > 1)
267 				ls_list(arcn, now, listf);
268 			else {
269 				(void)fputs(arcn->name, listf);
270 				vfpart = 1;
271 			}
272 		}
273 
274 		/*
275 		 * if required, chdir around.
276 		 */
277 		if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
278 			if (chdir(arcn->pat->chdname) != 0)
279 				syswarn(1, errno, "Cannot chdir to %s",
280 				    arcn->pat->chdname);
281 
282 		/*
283 		 * all ok, extract this member based on type
284 		 */
285 		if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
286 			/*
287 			 * process archive members that are not regular files.
288 			 * throw out padding and any data that might follow the
289 			 * header (as determined by the format).
290 			 */
291 			if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
292 				res = lnk_creat(arcn);
293 			else
294 				res = node_creat(arcn);
295 
296 			(void)rd_skip(arcn->skip + arcn->pad);
297 			if (res < 0)
298 				purg_lnk(arcn);
299 
300 			if (vflag && vfpart) {
301 				(void)putc('\n', listf);
302 				vfpart = 0;
303 			}
304 			continue;
305 		}
306 		/*
307 		 * we have a file with data here. If we can not create it, skip
308 		 * over the data and purge the name from hard link table
309 		 */
310 		if ((fd = file_creat(arcn)) < 0) {
311 			(void)rd_skip(arcn->skip + arcn->pad);
312 			purg_lnk(arcn);
313 			continue;
314 		}
315 		/*
316 		 * extract the file from the archive and skip over padding and
317 		 * any unprocessed data
318 		 */
319 		res = (*frmt->rd_data)(arcn, fd, &cnt);
320 		file_close(arcn, fd);
321 		if (vflag && vfpart) {
322 			(void)putc('\n', listf);
323 			vfpart = 0;
324 		}
325 		if (!res)
326 			(void)rd_skip(cnt + arcn->pad);
327 
328 		/*
329 		 * if required, chdir around.
330 		 */
331 		if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
332 			if (fchdir(cwdfd) != 0)
333 				syswarn(1, errno,
334 				    "Can't fchdir to starting directory");
335 	}
336 
337 	/*
338 	 * all done, restore directory modes and times as required; make sure
339 	 * all patterns supplied by the user were matched; block off signals
340 	 * to avoid chance for multiple entry into the cleanup code.
341 	 */
342 	(void)(*frmt->end_rd)();
343 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
344 	ar_close();
345 	proc_dir();
346 	pat_chk();
347 }
348 
349 /*
350  * wr_archive()
351  *	Write an archive. used in both creating a new archive and appends on
352  *	previously written archive.
353  */
354 
355 static void
356 wr_archive(ARCHD *arcn, int is_app)
357 {
358 	int res;
359 	int hlk;
360 	int wr_one;
361 	off_t cnt;
362 	int (*wrf)(ARCHD *);
363 	int fd = -1;
364 	time_t now;
365 
366 	/*
367 	 * if this format supports hard link storage, start up the database
368 	 * that detects them.
369 	 */
370 	if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
371 		return;
372 
373 	/*
374 	 * start up the file traversal code and format specific write
375 	 */
376 	if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
377 		return;
378 	wrf = frmt->wr;
379 
380 	/*
381 	 * When we are doing interactive rename, we store the mapping of names
382 	 * so we can fix up hard links files later in the archive.
383 	 */
384 	if (iflag && (name_start() < 0))
385 		return;
386 
387 	/*
388 	 * if this is not append, and there are no files, we do not write a
389 	 * trailer
390 	 */
391 	wr_one = is_app;
392 
393 	now = time(NULL);
394 
395 	/*
396 	 * while there are files to archive, process them one at at time
397 	 */
398 	while (next_file(arcn) == 0) {
399 		/*
400 		 * check if this file meets user specified options match.
401 		 */
402 		if (sel_chk(arcn) != 0) {
403 			ftree_notsel();
404 			continue;
405 		}
406 		fd = -1;
407 		if (uflag) {
408 			/*
409 			 * only archive if this file is newer than a file with
410 			 * the same name that is already stored on the archive
411 			 */
412 			if ((res = chk_ftime(arcn)) < 0)
413 				break;
414 			if (res > 0)
415 				continue;
416 		}
417 
418 		/*
419 		 * this file is considered selected now. see if this is a hard
420 		 * link to a file already stored
421 		 */
422 		ftree_sel(arcn);
423 		if (hlk && (chk_lnk(arcn) < 0))
424 			break;
425 
426 		if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
427 		    (arcn->type == PAX_CTG)) {
428 			/*
429 			 * we will have to read this file. by opening it now we
430 			 * can avoid writing a header to the archive for a file
431 			 * we were later unable to read (we also purge it from
432 			 * the link table).
433 			 */
434 			if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
435 				syswarn(1,errno, "Unable to open %s to read",
436 					arcn->org_name);
437 				purg_lnk(arcn);
438 				continue;
439 			}
440 		}
441 
442 		/*
443 		 * Now modify the name as requested by the user
444 		 */
445 		if ((res = mod_name(arcn)) < 0) {
446 			/*
447 			 * name modification says to skip this file, close the
448 			 * file and purge link table entry
449 			 */
450 			rdfile_close(arcn, &fd);
451 			purg_lnk(arcn);
452 			break;
453 		}
454 
455 		if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
456 			/*
457 			 * unable to obtain the crc we need, close the file,
458 			 * purge link table entry
459 			 */
460 			rdfile_close(arcn, &fd);
461 			purg_lnk(arcn);
462 			continue;
463 		}
464 
465 		if (vflag) {
466 			if (vflag > 1)
467 				ls_list(arcn, now, listf);
468 			else {
469 				(void)fputs(arcn->name, listf);
470 				vfpart = 1;
471 			}
472 		}
473 		++flcnt;
474 
475 		/*
476 		 * looks safe to store the file, have the format specific
477 		 * routine write routine store the file header on the archive
478 		 */
479 		if ((res = (*wrf)(arcn)) < 0) {
480 			rdfile_close(arcn, &fd);
481 			break;
482 		}
483 		wr_one = 1;
484 		if (res > 0) {
485 			/*
486 			 * format write says no file data needs to be stored
487 			 * so we are done messing with this file
488 			 */
489 			if (vflag && vfpart) {
490 				(void)putc('\n', listf);
491 				vfpart = 0;
492 			}
493 			rdfile_close(arcn, &fd);
494 			continue;
495 		}
496 
497 		/*
498 		 * Add file data to the archive, quit on write error. if we
499 		 * cannot write the entire file contents to the archive we
500 		 * must pad the archive to replace the missing file data
501 		 * (otherwise during an extract the file header for the file
502 		 * which FOLLOWS this one will not be where we expect it to
503 		 * be).
504 		 */
505 		res = (*frmt->wr_data)(arcn, fd, &cnt);
506 		rdfile_close(arcn, &fd);
507 		if (vflag && vfpart) {
508 			(void)putc('\n', listf);
509 			vfpart = 0;
510 		}
511 		if (res < 0)
512 			break;
513 
514 		/*
515 		 * pad as required, cnt is number of bytes not written
516 		 */
517 		if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
518 		    ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
519 			break;
520 	}
521 
522 	/*
523 	 * tell format to write trailer; pad to block boundary; reset directory
524 	 * mode/access times, and check if all patterns supplied by the user
525 	 * were matched. block off signals to avoid chance for multiple entry
526 	 * into the cleanup code
527 	 */
528 	if (wr_one) {
529 		(*frmt->end_wr)();
530 		wr_fin();
531 	}
532 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
533 	ar_close();
534 	if (tflag)
535 		proc_dir();
536 	ftree_chk();
537 }
538 
539 /*
540  * append()
541  *	Add file to previously written archive. Archive format specified by the
542  *	user must agree with archive. The archive is read first to collect
543  *	modification times (if -u) and locate the archive trailer. The archive
544  *	is positioned in front of the record with the trailer and wr_archive()
545  *	is called to add the new members.
546  *	PAX IMPLEMENTATION DETAIL NOTE:
547  *	-u is implemented by adding the new members to the end of the archive.
548  *	Care is taken so that these do not end up as links to the older
549  *	version of the same file already stored in the archive. It is expected
550  *	when extraction occurs these newer versions will over-write the older
551  *	ones stored "earlier" in the archive (this may be a bad assumption as
552  *	it depends on the implementation of the program doing the extraction).
553  *	It is really difficult to splice in members without either re-writing
554  *	the entire archive (from the point were the old version was), or having
555  *	assistance of the format specification in terms of a special update
556  *	header that invalidates a previous archive record. The POSIX spec left
557  *	the method used to implement -u unspecified. This pax is able to
558  *	over write existing files that it creates.
559  */
560 
561 void
562 append(void)
563 {
564 	ARCHD *arcn;
565 	int res;
566 	ARCHD archd;
567 	FSUB *orgfrmt;
568 	int udev;
569 	off_t tlen;
570 
571 	arcn = &archd;
572 	orgfrmt = frmt;
573 
574 	/*
575 	 * Do not allow an append operation if the actual archive is of a
576 	 * different format than the user specified format.
577 	 */
578 	if (get_arc() < 0)
579 		return;
580 	if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
581 		paxwarn(1, "Cannot mix current archive format %s with %s",
582 		    frmt->name, orgfrmt->name);
583 		return;
584 	}
585 
586 	/*
587 	 * pass the format any options and start up format
588 	 */
589 	if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
590 		return;
591 
592 	/*
593 	 * if we only are adding members that are newer, we need to save the
594 	 * mod times for all files we see.
595 	 */
596 	if (uflag && (ftime_start() < 0))
597 		return;
598 
599 	/*
600 	 * some archive formats encode hard links by recording the device and
601 	 * file serial number (inode) but copy the file anyway (multiple times)
602 	 * to the archive. When we append, we run the risk that newly added
603 	 * files may have the same device and inode numbers as those recorded
604 	 * on the archive but during a previous run. If this happens, when the
605 	 * archive is extracted we get INCORRECT hard links. We avoid this by
606 	 * remapping the device numbers so that newly added files will never
607 	 * use the same device number as one found on the archive. remapping
608 	 * allows new members to safely have links among themselves. remapping
609 	 * also avoids problems with file inode (serial number) truncations
610 	 * when the inode number is larger than storage space in the archive
611 	 * header. See the remap routines for more details.
612 	 */
613 	if ((udev = frmt->udev) && (dev_start() < 0))
614 		return;
615 
616 	/*
617 	 * reading the archive may take a long time. If verbose tell the user
618 	 */
619 	if (vflag) {
620 		(void)fprintf(listf,
621 			"%s: Reading archive to position at the end...", argv0);
622 		vfpart = 1;
623 	}
624 
625 	/*
626 	 * step through the archive until the format says it is done
627 	 */
628 	while (next_head(arcn) == 0) {
629 		/*
630 		 * check if this file meets user specified options.
631 		 */
632 		if (sel_chk(arcn) != 0) {
633 			if (rd_skip(arcn->skip + arcn->pad) == 1)
634 				break;
635 			continue;
636 		}
637 
638 		if (uflag) {
639 			/*
640 			 * see if this is the newest version of this file has
641 			 * already been seen, if so skip.
642 			 */
643 			if ((res = chk_ftime(arcn)) < 0)
644 				break;
645 			if (res > 0) {
646 				if (rd_skip(arcn->skip + arcn->pad) == 1)
647 					break;
648 				continue;
649 			}
650 		}
651 
652 		/*
653 		 * Store this device number. Device numbers seen during the
654 		 * read phase of append will cause newly appended files with a
655 		 * device number seen in the old part of the archive to be
656 		 * remapped to an unused device number.
657 		 */
658 		if ((udev && (add_dev(arcn) < 0)) ||
659 		    (rd_skip(arcn->skip + arcn->pad) == 1))
660 			break;
661 	}
662 
663 	/*
664 	 * done, finish up read and get the number of bytes to back up so we
665 	 * can add new members. The format might have used the hard link table,
666 	 * purge it.
667 	 */
668 	tlen = (*frmt->end_rd)();
669 	lnk_end();
670 
671 	/*
672 	 * try to position for write, if this fails quit. if any error occurs,
673 	 * we will refuse to write
674 	 */
675 	if (appnd_start(tlen) < 0)
676 		return;
677 
678 	/*
679 	 * tell the user we are done reading.
680 	 */
681 	if (vflag && vfpart) {
682 		(void)fputs("done.\n", listf);
683 		vfpart = 0;
684 	}
685 
686 	/*
687 	 * go to the writing phase to add the new members
688 	 */
689 	wr_archive(arcn, 1);
690 }
691 
692 /*
693  * archive()
694  *	write a new archive
695  */
696 
697 void
698 archive(void)
699 {
700 	ARCHD archd;
701 
702 	/*
703 	 * if we only are adding members that are newer, we need to save the
704 	 * mod times for all files; set up for writing; pass the format any
705 	 * options write the archive
706 	 */
707 	if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
708 		return;
709 	if ((*frmt->options)() < 0)
710 		return;
711 
712 	wr_archive(&archd, 0);
713 }
714 
715 /*
716  * copy()
717  *	copy files from one part of the file system to another. this does not
718  *	use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
719  *	archive was written and then extracted in the destination directory
720  *	(except the files are forced to be under the destination directory).
721  */
722 
723 void
724 copy(void)
725 {
726 	ARCHD *arcn;
727 	int res;
728 	int fddest;
729 	char *dest_pt;
730 	int dlen;
731 	int drem;
732 	int fdsrc = -1;
733 	struct stat sb;
734 	ARCHD archd;
735 	char dirbuf[PAXPATHLEN+1];
736 
737 	arcn = &archd;
738 	/*
739 	 * set up the destination dir path and make sure it is a directory. We
740 	 * make sure we have a trailing / on the destination
741 	 */
742 	dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
743 	dest_pt = dirbuf + dlen;
744 	if (*(dest_pt-1) != '/') {
745 		*dest_pt++ = '/';
746 		++dlen;
747 	}
748 	*dest_pt = '\0';
749 	drem = PAXPATHLEN - dlen;
750 
751 	if (stat(dirptr, &sb) < 0) {
752 		syswarn(1, errno, "Cannot access destination directory %s",
753 			dirptr);
754 		return;
755 	}
756 	if (!S_ISDIR(sb.st_mode)) {
757 		paxwarn(1, "Destination is not a directory %s", dirptr);
758 		return;
759 	}
760 
761 	/*
762 	 * start up the hard link table; file traversal routines and the
763 	 * modification time and access mode database
764 	 */
765 	if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
766 		return;
767 
768 	/*
769 	 * When we are doing interactive rename, we store the mapping of names
770 	 * so we can fix up hard links files later in the archive.
771 	 */
772 	if (iflag && (name_start() < 0))
773 		return;
774 
775 	/*
776 	 * set up to cp file trees
777 	 */
778 	cp_start();
779 
780 	/*
781 	 * while there are files to archive, process them
782 	 */
783 	while (next_file(arcn) == 0) {
784 		fdsrc = -1;
785 
786 		/*
787 		 * check if this file meets user specified options
788 		 */
789 		if (sel_chk(arcn) != 0) {
790 			ftree_notsel();
791 			continue;
792 		}
793 
794 		/*
795 		 * if there is already a file in the destination directory with
796 		 * the same name and it is newer, skip the one stored on the
797 		 * archive.
798 		 * NOTE: this test is done BEFORE name modifications as
799 		 * specified by pax. this can be confusing to the user who
800 		 * might expect the test to be done on an existing file AFTER
801 		 * the name mod. In honesty the pax spec is probably flawed in
802 		 * this respect
803 		 */
804 		if (uflag || Dflag) {
805 			/*
806 			 * create the destination name
807 			 */
808 			if (*(arcn->name) == '/')
809 				res = 1;
810 			else
811 				res = 0;
812 			if ((arcn->nlen - res) > drem) {
813 				paxwarn(1, "Destination pathname too long %s",
814 					arcn->name);
815 				continue;
816 			}
817 			(void)strncpy(dest_pt, arcn->name + res, drem);
818 			dirbuf[PAXPATHLEN] = '\0';
819 
820 			/*
821 			 * if existing file is same age or newer skip
822 			 */
823 			res = lstat(dirbuf, &sb);
824 			*dest_pt = '\0';
825 
826 		    	if (res == 0) {
827 				if (uflag && Dflag) {
828 					if ((arcn->sb.st_mtime<=sb.st_mtime) &&
829 			    		    (arcn->sb.st_ctime<=sb.st_ctime))
830 						continue;
831 				} else if (Dflag) {
832 					if (arcn->sb.st_ctime <= sb.st_ctime)
833 						continue;
834 				} else if (arcn->sb.st_mtime <= sb.st_mtime)
835 					continue;
836 			}
837 		}
838 
839 		/*
840 		 * this file is considered selected. See if this is a hard link
841 		 * to a previous file; modify the name as requested by the
842 		 * user; set the final destination.
843 		 */
844 		ftree_sel(arcn);
845 		if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
846 			break;
847 		if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
848 			/*
849 			 * skip file, purge from link table
850 			 */
851 			purg_lnk(arcn);
852 			continue;
853 		}
854 
855 		/*
856 		 * Non standard -Y and -Z flag. When the existing file is
857 		 * same age or newer skip
858 		 */
859 		if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
860 			if (Yflag && Zflag) {
861 				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
862 				    (arcn->sb.st_ctime <= sb.st_ctime))
863 					continue;
864 			} else if (Yflag) {
865 				if (arcn->sb.st_ctime <= sb.st_ctime)
866 					continue;
867 			} else if (arcn->sb.st_mtime <= sb.st_mtime)
868 				continue;
869 		}
870 
871 		if (vflag) {
872 			(void)fputs(arcn->name, listf);
873 			vfpart = 1;
874 		}
875 		++flcnt;
876 
877 		/*
878 		 * try to create a hard link to the src file if requested
879 		 * but make sure we are not trying to overwrite ourselves.
880 		 */
881 		if (lflag)
882 			res = cross_lnk(arcn);
883 		else
884 			res = chk_same(arcn);
885 		if (res <= 0) {
886 			if (vflag && vfpart) {
887 				(void)putc('\n', listf);
888 				vfpart = 0;
889 			}
890 			continue;
891 		}
892 
893 		/*
894 		 * have to create a new file
895 		 */
896 		if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
897 			/*
898 			 * create a link or special file
899 			 */
900 			if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
901 				res = lnk_creat(arcn);
902 			else
903 				res = node_creat(arcn);
904 			if (res < 0)
905 				purg_lnk(arcn);
906 			if (vflag && vfpart) {
907 				(void)putc('\n', listf);
908 				vfpart = 0;
909 			}
910 			continue;
911 		}
912 
913 		/*
914 		 * have to copy a regular file to the destination directory.
915 		 * first open source file and then create the destination file
916 		 */
917 		if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
918 			syswarn(1, errno, "Unable to open %s to read",
919 			    arcn->org_name);
920 			purg_lnk(arcn);
921 			continue;
922 		}
923 		if ((fddest = file_creat(arcn)) < 0) {
924 			rdfile_close(arcn, &fdsrc);
925 			purg_lnk(arcn);
926 			continue;
927 		}
928 
929 		/*
930 		 * copy source file data to the destination file
931 		 */
932 		cp_file(arcn, fdsrc, fddest);
933 		file_close(arcn, fddest);
934 		rdfile_close(arcn, &fdsrc);
935 
936 		if (vflag && vfpart) {
937 			(void)putc('\n', listf);
938 			vfpart = 0;
939 		}
940 	}
941 
942 	/*
943 	 * restore directory modes and times as required; make sure all
944 	 * patterns were selected block off signals to avoid chance for
945 	 * multiple entry into the cleanup code.
946 	 */
947 	(void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
948 	ar_close();
949 	proc_dir();
950 	ftree_chk();
951 }
952 
953 /*
954  * next_head()
955  *	try to find a valid header in the archive. Uses format specific
956  *	routines to extract the header and id the trailer. Trailers may be
957  *	located within a valid header or in an invalid header (the location
958  *	is format specific. The inhead field from the option table tells us
959  *	where to look for the trailer).
960  *	We keep reading (and resyncing) until we get enough contiguous data
961  *	to check for a header. If we cannot find one, we shift by a byte
962  *	add a new byte from the archive to the end of the buffer and try again.
963  *	If we get a read error, we throw out what we have (as we must have
964  *	contiguous data) and start over again.
965  *	ASSUMED: headers fit within a BLKMULT header.
966  * Return:
967  *	0 if we got a header, -1 if we are unable to ever find another one
968  *	(we reached the end of input, or we reached the limit on retries. see
969  *	the specs for rd_wrbuf() for more details)
970  */
971 
972 static int
973 next_head(ARCHD *arcn)
974 {
975 	int ret;
976 	char *hdend;
977 	int res;
978 	int shftsz;
979 	int hsz;
980 	int in_resync = 0; 	/* set when we are in resync mode */
981 	int cnt = 0;			/* counter for trailer function */
982 	int first = 1;			/* on 1st read, EOF isn't premature. */
983 
984 	/*
985 	 * set up initial conditions, we want a whole frmt->hsz block as we
986 	 * have no data yet.
987 	 */
988 	res = hsz = frmt->hsz;
989 	hdend = hdbuf;
990 	shftsz = hsz - 1;
991 	for(;;) {
992 		/*
993 		 * keep looping until we get a contiguous FULL buffer
994 		 * (frmt->hsz is the proper size)
995 		 */
996 		for (;;) {
997 			if ((ret = rd_wrbuf(hdend, res)) == res)
998 				break;
999 
1000 			/*
1001 			 * If we read 0 bytes (EOF) from an archive when we
1002 			 * expect to find a header, we have stepped upon
1003 			 * an archive without the customary block of zeroes
1004 			 * end marker.  It's just stupid to error out on
1005 			 * them, so exit gracefully.
1006 			 */
1007 			if (first && ret == 0)
1008 				return(-1);
1009 			first = 0;
1010 
1011 			/*
1012 			 * some kind of archive read problem, try to resync the
1013 			 * storage device, better give the user the bad news.
1014 			 */
1015 			if ((ret == 0) || (rd_sync() < 0)) {
1016 				paxwarn(1,"Premature end of file on archive read");
1017 				return(-1);
1018 			}
1019 			if (!in_resync) {
1020 				if (act == APPND) {
1021 					paxwarn(1,
1022 					  "Archive I/O error, cannot continue");
1023 					return(-1);
1024 				}
1025 				paxwarn(1,"Archive I/O error. Trying to recover.");
1026 				++in_resync;
1027 			}
1028 
1029 			/*
1030 			 * oh well, throw it all out and start over
1031 			 */
1032 			res = hsz;
1033 			hdend = hdbuf;
1034 		}
1035 
1036 		/*
1037 		 * ok we have a contiguous buffer of the right size. Call the
1038 		 * format read routine. If this was not a valid header and this
1039 		 * format stores trailers outside of the header, call the
1040 		 * format specific trailer routine to check for a trailer. We
1041 		 * have to watch out that we do not mis-identify file data or
1042 		 * block padding as a header or trailer. Format specific
1043 		 * trailer functions must NOT check for the trailer while we
1044 		 * are running in resync mode. Some trailer functions may tell
1045 		 * us that this block cannot contain a valid header either, so
1046 		 * we then throw out the entire block and start over.
1047 		 */
1048 		if ((*frmt->rd)(arcn, hdbuf) == 0)
1049 			break;
1050 
1051 		if (!frmt->inhead) {
1052 			/*
1053 			 * this format has trailers outside of valid headers
1054 			 */
1055 			if ((ret = (*frmt->trail_tar)(hdbuf,in_resync,&cnt)) == 0){
1056 				/*
1057 				 * valid trailer found, drain input as required
1058 				 */
1059 				ar_drain();
1060 				return(-1);
1061 			}
1062 
1063 			if (ret == 1) {
1064 				/*
1065 				 * we are in resync and we were told to throw
1066 				 * the whole block out because none of the
1067 				 * bytes in this block can be used to form a
1068 				 * valid header
1069 				 */
1070 				res = hsz;
1071 				hdend = hdbuf;
1072 				continue;
1073 			}
1074 		}
1075 
1076 		/*
1077 		 * Brute force section.
1078 		 * not a valid header. We may be able to find a header yet. So
1079 		 * we shift over by one byte, and set up to read one byte at a
1080 		 * time from the archive and place it at the end of the buffer.
1081 		 * We will keep moving byte at a time until we find a header or
1082 		 * get a read error and have to start over.
1083 		 */
1084 		if (!in_resync) {
1085 			if (act == APPND) {
1086 				paxwarn(1,"Unable to append, archive header flaw");
1087 				return(-1);
1088 			}
1089 			paxwarn(1,"Invalid header, starting valid header search.");
1090 			++in_resync;
1091 		}
1092 		memmove(hdbuf, hdbuf+1, shftsz);
1093 		res = 1;
1094 		hdend = hdbuf + shftsz;
1095 	}
1096 
1097 	/*
1098 	 * ok got a valid header, check for trailer if format encodes it in
1099 	 * the header.
1100 	 */
1101 	if (frmt->inhead && ((*frmt->trail_cpio)(arcn) == 0)) {
1102 		/*
1103 		 * valid trailer found, drain input as required
1104 		 */
1105 		ar_drain();
1106 		return(-1);
1107 	}
1108 
1109 	++flcnt;
1110 	return(0);
1111 }
1112 
1113 /*
1114  * get_arc()
1115  *	Figure out what format an archive is. Handles archive with flaws by
1116  *	brute force searches for a legal header in any supported format. The
1117  *	format id routines have to be careful to NOT mis-identify a format.
1118  *	ASSUMED: headers fit within a BLKMULT header.
1119  * Return:
1120  *	0 if archive found -1 otherwise
1121  */
1122 
1123 static int
1124 get_arc(void)
1125 {
1126 	int i;
1127 	int hdsz = 0;
1128 	int res;
1129 	int minhd = BLKMULT;
1130 	char *hdend;
1131 	int notice = 0;
1132 
1133 	/*
1134 	 * find the smallest header size in all archive formats and then set up
1135 	 * to read the archive.
1136 	 */
1137 	for (i = 0; ford[i] >= 0; ++i) {
1138 		if (fsub[ford[i]].hsz < minhd)
1139 			minhd = fsub[ford[i]].hsz;
1140 	}
1141 	if (rd_start() < 0)
1142 		return(-1);
1143 	res = BLKMULT;
1144 	hdsz = 0;
1145 	hdend = hdbuf;
1146 	for(;;) {
1147 		for (;;) {
1148 			/*
1149 			 * fill the buffer with at least the smallest header
1150 			 */
1151 			i = rd_wrbuf(hdend, res);
1152 			if (i > 0)
1153 				hdsz += i;
1154 			if (hdsz >= minhd)
1155 				break;
1156 
1157 			/*
1158 			 * if we cannot recover from a read error quit
1159 			 */
1160 			if ((i == 0) || (rd_sync() < 0))
1161 				goto out;
1162 
1163 			/*
1164 			 * when we get an error none of the data we already
1165 			 * have can be used to create a legal header (we just
1166 			 * got an error in the middle), so we throw it all out
1167 			 * and refill the buffer with fresh data.
1168 			 */
1169 			res = BLKMULT;
1170 			hdsz = 0;
1171 			hdend = hdbuf;
1172 			if (!notice) {
1173 				if (act == APPND)
1174 					return(-1);
1175 				paxwarn(1,"Cannot identify format. Searching...");
1176 				++notice;
1177 			}
1178 		}
1179 
1180 		/*
1181 		 * we have at least the size of the smallest header in any
1182 		 * archive format. Look to see if we have a match. The array
1183 		 * ford[] is used to specify the header id order to reduce the
1184 		 * chance of incorrectly id'ing a valid header (some formats
1185 		 * may be subsets of each other and the order would then be
1186 		 * important).
1187 		 */
1188 		for (i = 0; ford[i] >= 0; ++i) {
1189 			if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
1190 				continue;
1191 			frmt = &(fsub[ford[i]]);
1192 			/*
1193 			 * yuck, to avoid slow special case code in the extract
1194 			 * routines, just push this header back as if it was
1195 			 * not seen. We have left extra space at start of the
1196 			 * buffer for this purpose. This is a bit ugly, but
1197 			 * adding all the special case code is far worse.
1198 			 */
1199 			pback(hdbuf, hdsz);
1200 			return(0);
1201 		}
1202 
1203 		/*
1204 		 * We have a flawed archive, no match. we start searching, but
1205 		 * we never allow additions to flawed archives
1206 		 */
1207 		if (!notice) {
1208 			if (act == APPND)
1209 				return(-1);
1210 			paxwarn(1, "Cannot identify format. Searching...");
1211 			++notice;
1212 		}
1213 
1214 		/*
1215 		 * brute force search for a header that we can id.
1216 		 * we shift through byte at a time. this is slow, but we cannot
1217 		 * determine the nature of the flaw in the archive in a
1218 		 * portable manner
1219 		 */
1220 		if (--hdsz > 0) {
1221 			memmove(hdbuf, hdbuf+1, hdsz);
1222 			res = BLKMULT - hdsz;
1223 			hdend = hdbuf + hdsz;
1224 		} else {
1225 			res = BLKMULT;
1226 			hdend = hdbuf;
1227 			hdsz = 0;
1228 		}
1229 	}
1230 
1231     out:
1232 	/*
1233 	 * we cannot find a header, bow, apologize and quit
1234 	 */
1235 	paxwarn(1, "Sorry, unable to determine archive format.");
1236 	return(-1);
1237 }
1238