1 /* $OpenBSD: ar_subs.c,v 1.14 1998/09/20 02:22:21 millert Exp $ */
2 /* $NetBSD: ar_subs.c,v 1.5 1995/03/21 09:07:06 cgd Exp $ */
5 * Copyright (c) 1992 Keith Muller.
6 * Copyright (c) 1992, 1993
7 * The Regents of the University of California. All rights reserved.
9 * This code is derived from software contributed to Berkeley by
10 * Keith Muller of the University of California, San Diego.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 static char sccsid[] = "@(#)ar_subs.c 8.2 (Berkeley) 4/18/94";
45 static char rcsid[] = "$OpenBSD: ar_subs.c,v 1.14 1998/09/20 02:22:21 millert Exp $";
49 #include <sys/types.h>
53 #include <sys/param.h>
64 static void wr_archive __P((register ARCHD *, int is_app));
65 static int get_arc __P((void));
66 static int next_head __P((register ARCHD *));
67 extern sigset_t s_mask;
70 * Routines which control the overall operation modes of pax as specified by
71 * the user: list, append, read ...
74 static char hdbuf[BLKMULT]; /* space for archive header on read */
75 u_long flcnt; /* number of files processed */
79 * list the contents of an archive which match user supplied pattern(s)
80 * (no pattern matches all).
98 * figure out archive type; pass any format specific options to the
99 * archive option processing routine; call the format init routine. We
100 * also save current time for ls_list() so we do not make a system
101 * call for each file we need to print. If verbose (vflag) start up
102 * the name and group caches.
104 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
105 ((*frmt->st_rd)() < 0))
108 if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
114 * step through the archive until the format says it is done
116 while (next_head(arcn) == 0) {
118 * check for pattern, and user specified options match.
119 * When all patterns are matched we are done.
121 if ((res = pat_match(arcn)) < 0)
124 if ((res == 0) && (sel_chk(arcn) == 0)) {
126 * pattern resulted in a selected file
128 if (pat_sel(arcn) < 0)
132 * modify the name as requested by the user if name
133 * survives modification, do a listing of the file
135 if ((res = mod_name(arcn)) < 0)
138 ls_list(arcn, now, stdout);
142 * skip to next archive format header using values calculated
143 * by the format header read routine
145 if (rd_skip(arcn->skip + arcn->pad) == 1)
150 * all done, let format have a chance to cleanup, and make sure that
151 * the patterns supplied by the user were all matched
153 (void)(*frmt->end_rd)();
154 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
161 * extract the member(s) of an archive as specified by user supplied
162 * pattern(s) (no patterns extracts all members)
173 register ARCHD *arcn;
183 * figure out archive type; pass any format specific options to the
184 * archive option processing routine; call the format init routine;
185 * start up the directory modification time and access mode database
187 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
188 ((*frmt->st_rd)() < 0) || (dir_start() < 0))
192 * When we are doing interactive rename, we store the mapping of names
193 * so we can fix up hard links files later in the archive.
195 if (iflag && (name_start() < 0))
201 * step through each entry on the archive until the format read routine
204 while (next_head(arcn) == 0) {
207 * check for pattern, and user specified options match. When
208 * all the patterns are matched we are done
210 if ((res = pat_match(arcn)) < 0)
213 if ((res > 0) || (sel_chk(arcn) != 0)) {
215 * file is not selected. skip past any file data and
216 * padding and go back for the next archive member
218 (void)rd_skip(arcn->skip + arcn->pad);
223 * with -u or -D only extract when the archive member is newer
224 * than the file with the same name in the file system (nos
225 * test of being the same type is required).
226 * NOTE: this test is done BEFORE name modifications as
227 * specified by pax. this operation can be confusing to the
228 * user who might expect the test to be done on an existing
229 * file AFTER the name mod. In honesty the pax spec is probably
230 * flawed in this respect.
232 if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
233 if (uflag && Dflag) {
234 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
235 (arcn->sb.st_ctime <= sb.st_ctime)) {
236 (void)rd_skip(arcn->skip + arcn->pad);
240 if (arcn->sb.st_ctime <= sb.st_ctime) {
241 (void)rd_skip(arcn->skip + arcn->pad);
244 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
245 (void)rd_skip(arcn->skip + arcn->pad);
251 * this archive member is now been selected. modify the name.
253 if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
257 * a bad name mod, skip and purge name from link table
260 (void)rd_skip(arcn->skip + arcn->pad);
265 * Non standard -Y and -Z flag. When the exisiting file is
266 * same age or newer skip
268 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
269 if (Yflag && Zflag) {
270 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
271 (arcn->sb.st_ctime <= sb.st_ctime)) {
272 (void)rd_skip(arcn->skip + arcn->pad);
276 if (arcn->sb.st_ctime <= sb.st_ctime) {
277 (void)rd_skip(arcn->skip + arcn->pad);
280 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
281 (void)rd_skip(arcn->skip + arcn->pad);
288 ls_list(arcn, now, listf);
290 (void)fputs(arcn->name, listf);
296 * if required, chdir around.
298 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
299 if (chdir(arcn->pat->chdname) != 0)
300 syswarn(1, errno, "Cannot chdir to %s",
304 * all ok, extract this member based on type
306 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
308 * process archive members that are not regular files.
309 * throw out padding and any data that might follow the
310 * header (as determined by the format).
312 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
313 res = lnk_creat(arcn);
315 res = node_creat(arcn);
317 (void)rd_skip(arcn->skip + arcn->pad);
321 if (vflag && vfpart) {
322 (void)putc('\n', listf);
328 * we have a file with data here. If we can not create it, skip
329 * over the data and purge the name from hard link table
331 if ((fd = file_creat(arcn)) < 0) {
332 (void)rd_skip(arcn->skip + arcn->pad);
337 * extract the file from the archive and skip over padding and
338 * any unprocessed data
340 res = (*frmt->rd_data)(arcn, fd, &cnt);
341 file_close(arcn, fd);
342 if (vflag && vfpart) {
343 (void)putc('\n', listf);
347 (void)rd_skip(cnt + arcn->pad);
350 * if required, chdir around.
352 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
353 if (fchdir(cwdfd) != 0)
355 "Can't fchdir to starting directory");
359 * all done, restore directory modes and times as required; make sure
360 * all patterns supplied by the user were matched; block off signals
361 * to avoid chance for multiple entry into the cleanup code.
363 (void)(*frmt->end_rd)();
364 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
372 * Write an archive. used in both creating a new archive and appends on
373 * previously written archive.
378 wr_archive(register ARCHD *arcn, int is_app)
381 wr_archive(arcn, is_app)
382 register ARCHD *arcn;
395 * if this format supports hard link storage, start up the database
398 if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
402 * start up the file traversal code and format specific write
404 if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
409 * When we are doing interactive rename, we store the mapping of names
410 * so we can fix up hard links files later in the archive.
412 if (iflag && (name_start() < 0))
416 * if this not append, and there are no files, we do no write a trailer
423 * while there are files to archive, process them one at at time
425 while (next_file(arcn) == 0) {
427 * check if this file meets user specified options match.
429 if (sel_chk(arcn) != 0)
434 * only archive if this file is newer than a file with
435 * the same name that is already stored on the archive
437 if ((res = chk_ftime(arcn)) < 0)
444 * this file is considered selected now. see if this is a hard
445 * link to a file already stored
448 if (hlk && (chk_lnk(arcn) < 0))
451 if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
452 (arcn->type == PAX_CTG)) {
454 * we will have to read this file. by opening it now we
455 * can avoid writing a header to the archive for a file
456 * we were later unable to read (we also purge it from
459 if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
460 syswarn(1,errno, "Unable to open %s to read",
468 * Now modify the name as requested by the user
470 if ((res = mod_name(arcn)) < 0) {
472 * name modification says to skip this file, close the
473 * file and purge link table entry
475 rdfile_close(arcn, &fd);
480 if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
482 * unable to obtain the crc we need, close the file,
483 * purge link table entry
485 rdfile_close(arcn, &fd);
492 ls_list(arcn, now, listf);
494 (void)fputs(arcn->name, listf);
501 * looks safe to store the file, have the format specific
502 * routine write routine store the file header on the archive
504 if ((res = (*wrf)(arcn)) < 0) {
505 rdfile_close(arcn, &fd);
511 * format write says no file data needs to be stored
512 * so we are done messing with this file
514 if (vflag && vfpart) {
515 (void)putc('\n', listf);
518 rdfile_close(arcn, &fd);
523 * Add file data to the archive, quit on write error. if we
524 * cannot write the entire file contents to the archive we
525 * must pad the archive to replace the missing file data
526 * (otherwise during an extract the file header for the file
527 * which FOLLOWS this one will not be where we expect it to
530 res = (*frmt->wr_data)(arcn, fd, &cnt);
531 rdfile_close(arcn, &fd);
532 if (vflag && vfpart) {
533 (void)putc('\n', listf);
540 * pad as required, cnt is number of bytes not written
542 if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
543 ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
548 * tell format to write trailer; pad to block boundry; reset directory
549 * mode/access times, and check if all patterns supplied by the user
550 * were matched. block off signals to avoid chance for multiple entry
551 * into the cleanup code
557 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
566 * Add file to previously written archive. Archive format specified by the
567 * user must agree with archive. The archive is read first to collect
568 * modification times (if -u) and locate the archive trailer. The archive
569 * is positioned in front of the record with the trailer and wr_archive()
570 * is called to add the new members.
571 * PAX IMPLEMENTATION DETAIL NOTE:
572 * -u is implemented by adding the new members to the end of the archive.
573 * Care is taken so that these do not end up as links to the older
574 * version of the same file already stored in the archive. It is expected
575 * when extraction occurs these newer versions will over-write the older
576 * ones stored "earlier" in the archive (this may be a bad assumption as
577 * it depends on the implementation of the program doing the extraction).
578 * It is really difficult to splice in members without either re-writing
579 * the entire archive (from the point were the old version was), or having
580 * assistance of the format specification in terms of a special update
581 * header that invalidates a previous archive record. The posix spec left
582 * the method used to implement -u unspecified. This pax is able to
583 * over write existing files that it creates.
594 register ARCHD *arcn;
605 * Do not allow an append operation if the actual archive is of a
606 * different format than the user specified foramt.
610 if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
611 paxwarn(1, "Cannot mix current archive format %s with %s",
612 frmt->name, orgfrmt->name);
617 * pass the format any options and start up format
619 if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
623 * if we only are adding members that are newer, we need to save the
624 * mod times for all files we see.
626 if (uflag && (ftime_start() < 0))
630 * some archive formats encode hard links by recording the device and
631 * file serial number (inode) but copy the file anyway (multiple times)
632 * to the archive. When we append, we run the risk that newly added
633 * files may have the same device and inode numbers as those recorded
634 * on the archive but during a previous run. If this happens, when the
635 * archive is extracted we get INCORRECT hard links. We avoid this by
636 * remapping the device numbers so that newly added files will never
637 * use the same device number as one found on the archive. remapping
638 * allows new members to safely have links among themselves. remapping
639 * also avoids problems with file inode (serial number) truncations
640 * when the inode number is larger than storage space in the archive
641 * header. See the remap routines for more details.
643 if ((udev = frmt->udev) && (dev_start() < 0))
647 * reading the archive may take a long time. If verbose tell the user
651 "%s: Reading archive to position at the end...", argv0);
656 * step through the archive until the format says it is done
658 while (next_head(arcn) == 0) {
660 * check if this file meets user specified options.
662 if (sel_chk(arcn) != 0) {
663 if (rd_skip(arcn->skip + arcn->pad) == 1)
670 * see if this is the newest version of this file has
671 * already been seen, if so skip.
673 if ((res = chk_ftime(arcn)) < 0)
676 if (rd_skip(arcn->skip + arcn->pad) == 1)
683 * Store this device number. Device numbers seen during the
684 * read phase of append will cause newly appended files with a
685 * device number seen in the old part of the archive to be
686 * remapped to an unused device number.
688 if ((udev && (add_dev(arcn) < 0)) ||
689 (rd_skip(arcn->skip + arcn->pad) == 1))
694 * done, finish up read and get the number of bytes to back up so we
695 * can add new members. The format might have used the hard link table,
698 tlen = (*frmt->end_rd)();
702 * try to postion for write, if this fails quit. if any error occurs,
703 * we will refuse to write
705 if (appnd_start(tlen) < 0)
709 * tell the user we are done reading.
711 if (vflag && vfpart) {
712 (void)fputs("done.\n", listf);
717 * go to the writing phase to add the new members
724 * write a new archive
738 * if we only are adding members that are newer, we need to save the
739 * mod times for all files; set up for writing; pass the format any
740 * options write the archive
742 if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
744 if ((*frmt->options)() < 0)
747 wr_archive(&archd, 0);
752 * copy files from one part of the file system to another. this does not
753 * use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
754 * archive was written and then extracted in the destination directory
755 * (except the files are forced to be under the destination directory).
766 register ARCHD *arcn;
769 register char *dest_pt;
775 char dirbuf[PAXPATHLEN+1];
779 * set up the destination dir path and make sure it is a directory. We
780 * make sure we have a trailing / on the destination
782 dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
783 dest_pt = dirbuf + dlen;
784 if (*(dest_pt-1) != '/') {
789 drem = PAXPATHLEN - dlen;
791 if (stat(dirptr, &sb) < 0) {
792 syswarn(1, errno, "Cannot access destination directory %s",
796 if (!S_ISDIR(sb.st_mode)) {
797 paxwarn(1, "Destination is not a directory %s", dirptr);
802 * start up the hard link table; file traversal routines and the
803 * modification time and access mode database
805 if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
809 * When we are doing interactive rename, we store the mapping of names
810 * so we can fix up hard links files later in the archive.
812 if (iflag && (name_start() < 0))
816 * set up to cp file trees
821 * while there are files to archive, process them
823 while (next_file(arcn) == 0) {
827 * check if this file meets user specified options
829 if (sel_chk(arcn) != 0)
833 * if there is already a file in the destination directory with
834 * the same name and it is newer, skip the one stored on the
836 * NOTE: this test is done BEFORE name modifications as
837 * specified by pax. this can be confusing to the user who
838 * might expect the test to be done on an existing file AFTER
839 * the name mod. In honesty the pax spec is probably flawed in
842 if (uflag || Dflag) {
844 * create the destination name
846 if (*(arcn->name) == '/')
850 if ((arcn->nlen - res) > drem) {
851 paxwarn(1, "Destination pathname too long %s",
855 (void)strncpy(dest_pt, arcn->name + res, drem);
856 dirbuf[PAXPATHLEN] = '\0';
859 * if existing file is same age or newer skip
861 res = lstat(dirbuf, &sb);
865 if (uflag && Dflag) {
866 if ((arcn->sb.st_mtime<=sb.st_mtime) &&
867 (arcn->sb.st_ctime<=sb.st_ctime))
870 if (arcn->sb.st_ctime <= sb.st_ctime)
872 } else if (arcn->sb.st_mtime <= sb.st_mtime)
878 * this file is considered selected. See if this is a hard link
879 * to a previous file; modify the name as requested by the
880 * user; set the final destination.
883 if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
885 if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
887 * skip file, purge from link table
894 * Non standard -Y and -Z flag. When the exisiting file is
895 * same age or newer skip
897 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
898 if (Yflag && Zflag) {
899 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
900 (arcn->sb.st_ctime <= sb.st_ctime))
903 if (arcn->sb.st_ctime <= sb.st_ctime)
905 } else if (arcn->sb.st_mtime <= sb.st_mtime)
910 (void)fputs(arcn->name, listf);
916 * try to create a hard link to the src file if requested
917 * but make sure we are not trying to overwrite ourselves.
920 res = cross_lnk(arcn);
922 res = chk_same(arcn);
924 if (vflag && vfpart) {
925 (void)putc('\n', listf);
932 * have to create a new file
934 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
936 * create a link or special file
938 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
939 res = lnk_creat(arcn);
941 res = node_creat(arcn);
944 if (vflag && vfpart) {
945 (void)putc('\n', listf);
952 * have to copy a regular file to the destination directory.
953 * first open source file and then create the destination file
955 if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
956 syswarn(1, errno, "Unable to open %s to read",
961 if ((fddest = file_creat(arcn)) < 0) {
962 rdfile_close(arcn, &fdsrc);
968 * copy source file data to the destination file
970 cp_file(arcn, fdsrc, fddest);
971 file_close(arcn, fddest);
972 rdfile_close(arcn, &fdsrc);
974 if (vflag && vfpart) {
975 (void)putc('\n', listf);
981 * restore directory modes and times as required; make sure all
982 * patterns were selected block off signals to avoid chance for
983 * multiple entry into the cleanup code.
985 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
993 * try to find a valid header in the archive. Uses format specific
994 * routines to extract the header and id the trailer. Trailers may be
995 * located within a valid header or in an invalid header (the location
996 * is format specific. The inhead field from the option table tells us
997 * where to look for the trailer).
998 * We keep reading (and resyncing) until we get enough contiguous data
999 * to check for a header. If we cannot find one, we shift by a byte
1000 * add a new byte from the archive to the end of the buffer and try again.
1001 * If we get a read error, we throw out what we have (as we must have
1002 * contiguous data) and start over again.
1003 * ASSUMED: headers fit within a BLKMULT header.
1005 * 0 if we got a header, -1 if we are unable to ever find another one
1006 * (we reached the end of input, or we reached the limit on retries. see
1007 * the specs for rd_wrbuf() for more details)
1012 next_head(register ARCHD *arcn)
1016 register ARCHD *arcn;
1020 register char *hdend;
1022 register int shftsz;
1024 register int in_resync = 0; /* set when we are in resync mode */
1025 int cnt = 0; /* counter for trailer function */
1026 int first = 1; /* on 1st read, EOF isn't premature. */
1029 * set up initial conditions, we want a whole frmt->hsz block as we
1032 res = hsz = frmt->hsz;
1037 * keep looping until we get a contiguous FULL buffer
1038 * (frmt->hsz is the proper size)
1041 if ((ret = rd_wrbuf(hdend, res)) == res)
1045 * If we read 0 bytes (EOF) from an archive when we
1046 * expect to find a header, we have stepped upon
1047 * an archive without the customary block of zeroes
1048 * end marker. It's just stupid to error out on
1049 * them, so exit gracefully.
1051 if (first && ret == 0)
1056 * some kind of archive read problem, try to resync the
1057 * storage device, better give the user the bad news.
1059 if ((ret == 0) || (rd_sync() < 0)) {
1060 paxwarn(1,"Premature end of file on archive read");
1066 "Archive I/O error, cannot continue");
1069 paxwarn(1,"Archive I/O error. Trying to recover.");
1074 * oh well, throw it all out and start over
1081 * ok we have a contiguous buffer of the right size. Call the
1082 * format read routine. If this was not a valid header and this
1083 * format stores trailers outside of the header, call the
1084 * format specific trailer routine to check for a trailer. We
1085 * have to watch out that we do not mis-identify file data or
1086 * block padding as a header or trailer. Format specific
1087 * trailer functions must NOT check for the trailer while we
1088 * are running in resync mode. Some trailer functions may tell
1089 * us that this block cannot contain a valid header either, so
1090 * we then throw out the entire block and start over.
1092 if ((*frmt->rd)(arcn, hdbuf) == 0)
1095 if (!frmt->inhead) {
1097 * this format has trailers outside of valid headers
1099 if ((ret = (*frmt->trail)(hdbuf,in_resync,&cnt)) == 0){
1101 * valid trailer found, drain input as required
1109 * we are in resync and we were told to throw
1110 * the whole block out because none of the
1111 * bytes in this block can be used to form a
1121 * Brute force section.
1122 * not a valid header. We may be able to find a header yet. So
1123 * we shift over by one byte, and set up to read one byte at a
1124 * time from the archive and place it at the end of the buffer.
1125 * We will keep moving byte at a time until we find a header or
1126 * get a read error and have to start over.
1130 paxwarn(1,"Unable to append, archive header flaw");
1133 paxwarn(1,"Invalid header, starting valid header search.");
1136 memmove(hdbuf, hdbuf+1, shftsz);
1138 hdend = hdbuf + shftsz;
1142 * ok got a valid header, check for trailer if format encodes it in the
1143 * the header. NOTE: the parameters are different than trailer routines
1144 * which encode trailers outside of the header!
1146 if (frmt->inhead && ((*frmt->trail)(arcn) == 0)) {
1148 * valid trailer found, drain input as required
1160 * Figure out what format an archive is. Handles archive with flaws by
1161 * brute force searches for a legal header in any supported format. The
1162 * format id routines have to be careful to NOT mis-identify a format.
1163 * ASSUMED: headers fit within a BLKMULT header.
1165 * 0 if archive found -1 otherwise
1177 register int hdsz = 0;
1179 register int minhd = BLKMULT;
1184 * find the smallest header size in all archive formats and then set up
1185 * to read the archive.
1187 for (i = 0; ford[i] >= 0; ++i) {
1188 if (fsub[ford[i]].hsz < minhd)
1189 minhd = fsub[ford[i]].hsz;
1199 * fill the buffer with at least the smallest header
1201 i = rd_wrbuf(hdend, res);
1208 * if we cannot recover from a read error quit
1210 if ((i == 0) || (rd_sync() < 0))
1214 * when we get an error none of the data we already
1215 * have can be used to create a legal header (we just
1216 * got an error in the middle), so we throw it all out
1217 * and refill the buffer with fresh data.
1225 paxwarn(1,"Cannot identify format. Searching...");
1231 * we have at least the size of the smallest header in any
1232 * archive format. Look to see if we have a match. The array
1233 * ford[] is used to specify the header id order to reduce the
1234 * chance of incorrectly id'ing a valid header (some formats
1235 * may be subsets of each other and the order would then be
1238 for (i = 0; ford[i] >= 0; ++i) {
1239 if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
1241 frmt = &(fsub[ford[i]]);
1243 * yuck, to avoid slow special case code in the extract
1244 * routines, just push this header back as if it was
1245 * not seen. We have left extra space at start of the
1246 * buffer for this purpose. This is a bit ugly, but
1247 * adding all the special case code is far worse.
1254 * We have a flawed archive, no match. we start searching, but
1255 * we never allow additions to flawed archives
1260 paxwarn(1, "Cannot identify format. Searching...");
1265 * brute force search for a header that we can id.
1266 * we shift through byte at a time. this is slow, but we cannot
1267 * determine the nature of the flaw in the archive in a
1271 memmove(hdbuf, hdbuf+1, hdsz);
1272 res = BLKMULT - hdsz;
1273 hdend = hdbuf + hdsz;
1283 * we cannot find a header, bow, apologize and quit
1285 paxwarn(1, "Sorry, unable to determine archive format.");