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>
52 #include <sys/param.h>
63 static void wr_archive __P((register ARCHD *, int is_app));
64 static int get_arc __P((void));
65 static int next_head __P((register ARCHD *));
66 extern sigset_t s_mask;
69 * Routines which control the overall operation modes of pax as specified by
70 * the user: list, append, read ...
73 static char hdbuf[BLKMULT]; /* space for archive header on read */
74 u_long flcnt; /* number of files processed */
78 * list the contents of an archive which match user supplied pattern(s)
79 * (no pattern matches all).
97 * figure out archive type; pass any format specific options to the
98 * archive option processing routine; call the format init routine. We
99 * also save current time for ls_list() so we do not make a system
100 * call for each file we need to print. If verbose (vflag) start up
101 * the name and group caches.
103 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
104 ((*frmt->st_rd)() < 0))
107 if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
113 * step through the archive until the format says it is done
115 while (next_head(arcn) == 0) {
117 * check for pattern, and user specified options match.
118 * When all patterns are matched we are done.
120 if ((res = pat_match(arcn)) < 0)
123 if ((res == 0) && (sel_chk(arcn) == 0)) {
125 * pattern resulted in a selected file
127 if (pat_sel(arcn) < 0)
131 * modify the name as requested by the user if name
132 * survives modification, do a listing of the file
134 if ((res = mod_name(arcn)) < 0)
137 ls_list(arcn, now, stdout);
141 * skip to next archive format header using values calculated
142 * by the format header read routine
144 if (rd_skip(arcn->skip + arcn->pad) == 1)
149 * all done, let format have a chance to cleanup, and make sure that
150 * the patterns supplied by the user were all matched
152 (void)(*frmt->end_rd)();
153 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
160 * extract the member(s) of an archive as specified by user supplied
161 * pattern(s) (no patterns extracts all members)
172 register ARCHD *arcn;
182 * figure out archive type; pass any format specific options to the
183 * archive option processing routine; call the format init routine;
184 * start up the directory modification time and access mode database
186 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
187 ((*frmt->st_rd)() < 0) || (dir_start() < 0))
191 * When we are doing interactive rename, we store the mapping of names
192 * so we can fix up hard links files later in the archive.
194 if (iflag && (name_start() < 0))
200 * step through each entry on the archive until the format read routine
203 while (next_head(arcn) == 0) {
206 * check for pattern, and user specified options match. When
207 * all the patterns are matched we are done
209 if ((res = pat_match(arcn)) < 0)
212 if ((res > 0) || (sel_chk(arcn) != 0)) {
214 * file is not selected. skip past any file data and
215 * padding and go back for the next archive member
217 (void)rd_skip(arcn->skip + arcn->pad);
222 * with -u or -D only extract when the archive member is newer
223 * than the file with the same name in the file system (nos
224 * test of being the same type is required).
225 * NOTE: this test is done BEFORE name modifications as
226 * specified by pax. this operation can be confusing to the
227 * user who might expect the test to be done on an existing
228 * file AFTER the name mod. In honesty the pax spec is probably
229 * flawed in this respect.
231 if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
232 if (uflag && Dflag) {
233 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
234 (arcn->sb.st_ctime <= sb.st_ctime)) {
235 (void)rd_skip(arcn->skip + arcn->pad);
239 if (arcn->sb.st_ctime <= sb.st_ctime) {
240 (void)rd_skip(arcn->skip + arcn->pad);
243 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
244 (void)rd_skip(arcn->skip + arcn->pad);
250 * this archive member is now been selected. modify the name.
252 if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
256 * a bad name mod, skip and purge name from link table
259 (void)rd_skip(arcn->skip + arcn->pad);
264 * Non standard -Y and -Z flag. When the exisiting file is
265 * same age or newer skip
267 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
268 if (Yflag && Zflag) {
269 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
270 (arcn->sb.st_ctime <= sb.st_ctime)) {
271 (void)rd_skip(arcn->skip + arcn->pad);
275 if (arcn->sb.st_ctime <= sb.st_ctime) {
276 (void)rd_skip(arcn->skip + arcn->pad);
279 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
280 (void)rd_skip(arcn->skip + arcn->pad);
287 ls_list(arcn, now, listf);
289 (void)fputs(arcn->name, listf);
295 * if required, chdir around.
297 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
298 if (chdir(arcn->pat->chdname) != 0)
299 syswarn(1, errno, "Cannot chdir to %s",
303 * all ok, extract this member based on type
305 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
307 * process archive members that are not regular files.
308 * throw out padding and any data that might follow the
309 * header (as determined by the format).
311 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
312 res = lnk_creat(arcn);
314 res = node_creat(arcn);
316 (void)rd_skip(arcn->skip + arcn->pad);
320 if (vflag && vfpart) {
321 (void)putc('\n', listf);
327 * we have a file with data here. If we can not create it, skip
328 * over the data and purge the name from hard link table
330 if ((fd = file_creat(arcn)) < 0) {
331 (void)rd_skip(arcn->skip + arcn->pad);
336 * extract the file from the archive and skip over padding and
337 * any unprocessed data
339 res = (*frmt->rd_data)(arcn, fd, &cnt);
340 file_close(arcn, fd);
341 if (vflag && vfpart) {
342 (void)putc('\n', listf);
346 (void)rd_skip(cnt + arcn->pad);
349 * if required, chdir around.
351 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
352 if (fchdir(cwdfd) != 0)
354 "Can't fchdir to starting directory");
358 * all done, restore directory modes and times as required; make sure
359 * all patterns supplied by the user were matched; block off signals
360 * to avoid chance for multiple entry into the cleanup code.
362 (void)(*frmt->end_rd)();
363 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
371 * Write an archive. used in both creating a new archive and appends on
372 * previously written archive.
377 wr_archive(register ARCHD *arcn, int is_app)
380 wr_archive(arcn, is_app)
381 register ARCHD *arcn;
394 * if this format supports hard link storage, start up the database
397 if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
401 * start up the file traversal code and format specific write
403 if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
408 * When we are doing interactive rename, we store the mapping of names
409 * so we can fix up hard links files later in the archive.
411 if (iflag && (name_start() < 0))
415 * if this not append, and there are no files, we do no write a trailer
422 * while there are files to archive, process them one at at time
424 while (next_file(arcn) == 0) {
426 * check if this file meets user specified options match.
428 if (sel_chk(arcn) != 0)
433 * only archive if this file is newer than a file with
434 * the same name that is already stored on the archive
436 if ((res = chk_ftime(arcn)) < 0)
443 * this file is considered selected now. see if this is a hard
444 * link to a file already stored
447 if (hlk && (chk_lnk(arcn) < 0))
450 if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
451 (arcn->type == PAX_CTG)) {
453 * we will have to read this file. by opening it now we
454 * can avoid writing a header to the archive for a file
455 * we were later unable to read (we also purge it from
458 if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
459 syswarn(1,errno, "Unable to open %s to read",
467 * Now modify the name as requested by the user
469 if ((res = mod_name(arcn)) < 0) {
471 * name modification says to skip this file, close the
472 * file and purge link table entry
474 rdfile_close(arcn, &fd);
479 if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
481 * unable to obtain the crc we need, close the file,
482 * purge link table entry
484 rdfile_close(arcn, &fd);
491 ls_list(arcn, now, listf);
493 (void)fputs(arcn->name, listf);
500 * looks safe to store the file, have the format specific
501 * routine write routine store the file header on the archive
503 if ((res = (*wrf)(arcn)) < 0) {
504 rdfile_close(arcn, &fd);
510 * format write says no file data needs to be stored
511 * so we are done messing with this file
513 if (vflag && vfpart) {
514 (void)putc('\n', listf);
517 rdfile_close(arcn, &fd);
522 * Add file data to the archive, quit on write error. if we
523 * cannot write the entire file contents to the archive we
524 * must pad the archive to replace the missing file data
525 * (otherwise during an extract the file header for the file
526 * which FOLLOWS this one will not be where we expect it to
529 res = (*frmt->wr_data)(arcn, fd, &cnt);
530 rdfile_close(arcn, &fd);
531 if (vflag && vfpart) {
532 (void)putc('\n', listf);
539 * pad as required, cnt is number of bytes not written
541 if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
542 ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
547 * tell format to write trailer; pad to block boundry; reset directory
548 * mode/access times, and check if all patterns supplied by the user
549 * were matched. block off signals to avoid chance for multiple entry
550 * into the cleanup code
556 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
565 * Add file to previously written archive. Archive format specified by the
566 * user must agree with archive. The archive is read first to collect
567 * modification times (if -u) and locate the archive trailer. The archive
568 * is positioned in front of the record with the trailer and wr_archive()
569 * is called to add the new members.
570 * PAX IMPLEMENTATION DETAIL NOTE:
571 * -u is implemented by adding the new members to the end of the archive.
572 * Care is taken so that these do not end up as links to the older
573 * version of the same file already stored in the archive. It is expected
574 * when extraction occurs these newer versions will over-write the older
575 * ones stored "earlier" in the archive (this may be a bad assumption as
576 * it depends on the implementation of the program doing the extraction).
577 * It is really difficult to splice in members without either re-writing
578 * the entire archive (from the point were the old version was), or having
579 * assistance of the format specification in terms of a special update
580 * header that invalidates a previous archive record. The posix spec left
581 * the method used to implement -u unspecified. This pax is able to
582 * over write existing files that it creates.
593 register ARCHD *arcn;
604 * Do not allow an append operation if the actual archive is of a
605 * different format than the user specified foramt.
609 if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
610 paxwarn(1, "Cannot mix current archive format %s with %s",
611 frmt->name, orgfrmt->name);
616 * pass the format any options and start up format
618 if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
622 * if we only are adding members that are newer, we need to save the
623 * mod times for all files we see.
625 if (uflag && (ftime_start() < 0))
629 * some archive formats encode hard links by recording the device and
630 * file serial number (inode) but copy the file anyway (multiple times)
631 * to the archive. When we append, we run the risk that newly added
632 * files may have the same device and inode numbers as those recorded
633 * on the archive but during a previous run. If this happens, when the
634 * archive is extracted we get INCORRECT hard links. We avoid this by
635 * remapping the device numbers so that newly added files will never
636 * use the same device number as one found on the archive. remapping
637 * allows new members to safely have links among themselves. remapping
638 * also avoids problems with file inode (serial number) truncations
639 * when the inode number is larger than storage space in the archive
640 * header. See the remap routines for more details.
642 if ((udev = frmt->udev) && (dev_start() < 0))
646 * reading the archive may take a long time. If verbose tell the user
650 "%s: Reading archive to position at the end...", argv0);
655 * step through the archive until the format says it is done
657 while (next_head(arcn) == 0) {
659 * check if this file meets user specified options.
661 if (sel_chk(arcn) != 0) {
662 if (rd_skip(arcn->skip + arcn->pad) == 1)
669 * see if this is the newest version of this file has
670 * already been seen, if so skip.
672 if ((res = chk_ftime(arcn)) < 0)
675 if (rd_skip(arcn->skip + arcn->pad) == 1)
682 * Store this device number. Device numbers seen during the
683 * read phase of append will cause newly appended files with a
684 * device number seen in the old part of the archive to be
685 * remapped to an unused device number.
687 if ((udev && (add_dev(arcn) < 0)) ||
688 (rd_skip(arcn->skip + arcn->pad) == 1))
693 * done, finish up read and get the number of bytes to back up so we
694 * can add new members. The format might have used the hard link table,
697 tlen = (*frmt->end_rd)();
701 * try to postion for write, if this fails quit. if any error occurs,
702 * we will refuse to write
704 if (appnd_start(tlen) < 0)
708 * tell the user we are done reading.
710 if (vflag && vfpart) {
711 (void)fputs("done.\n", listf);
716 * go to the writing phase to add the new members
723 * write a new archive
737 * if we only are adding members that are newer, we need to save the
738 * mod times for all files; set up for writing; pass the format any
739 * options write the archive
741 if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
743 if ((*frmt->options)() < 0)
746 wr_archive(&archd, 0);
751 * copy files from one part of the file system to another. this does not
752 * use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
753 * archive was written and then extracted in the destination directory
754 * (except the files are forced to be under the destination directory).
765 register ARCHD *arcn;
768 register char *dest_pt;
774 char dirbuf[PAXPATHLEN+1];
778 * set up the destination dir path and make sure it is a directory. We
779 * make sure we have a trailing / on the destination
781 dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
782 dest_pt = dirbuf + dlen;
783 if (*(dest_pt-1) != '/') {
788 drem = PAXPATHLEN - dlen;
790 if (stat(dirptr, &sb) < 0) {
791 syswarn(1, errno, "Cannot access destination directory %s",
795 if (!S_ISDIR(sb.st_mode)) {
796 paxwarn(1, "Destination is not a directory %s", dirptr);
801 * start up the hard link table; file traversal routines and the
802 * modification time and access mode database
804 if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
808 * When we are doing interactive rename, we store the mapping of names
809 * so we can fix up hard links files later in the archive.
811 if (iflag && (name_start() < 0))
815 * set up to cp file trees
820 * while there are files to archive, process them
822 while (next_file(arcn) == 0) {
826 * check if this file meets user specified options
828 if (sel_chk(arcn) != 0)
832 * if there is already a file in the destination directory with
833 * the same name and it is newer, skip the one stored on the
835 * NOTE: this test is done BEFORE name modifications as
836 * specified by pax. this can be confusing to the user who
837 * might expect the test to be done on an existing file AFTER
838 * the name mod. In honesty the pax spec is probably flawed in
841 if (uflag || Dflag) {
843 * create the destination name
845 if (*(arcn->name) == '/')
849 if ((arcn->nlen - res) > drem) {
850 paxwarn(1, "Destination pathname too long %s",
854 (void)strncpy(dest_pt, arcn->name + res, drem);
855 dirbuf[PAXPATHLEN] = '\0';
858 * if existing file is same age or newer skip
860 res = lstat(dirbuf, &sb);
864 if (uflag && Dflag) {
865 if ((arcn->sb.st_mtime<=sb.st_mtime) &&
866 (arcn->sb.st_ctime<=sb.st_ctime))
869 if (arcn->sb.st_ctime <= sb.st_ctime)
871 } else if (arcn->sb.st_mtime <= sb.st_mtime)
877 * this file is considered selected. See if this is a hard link
878 * to a previous file; modify the name as requested by the
879 * user; set the final destination.
882 if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
884 if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
886 * skip file, purge from link table
893 * Non standard -Y and -Z flag. When the exisiting file is
894 * same age or newer skip
896 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
897 if (Yflag && Zflag) {
898 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
899 (arcn->sb.st_ctime <= sb.st_ctime))
902 if (arcn->sb.st_ctime <= sb.st_ctime)
904 } else if (arcn->sb.st_mtime <= sb.st_mtime)
909 (void)fputs(arcn->name, listf);
915 * try to create a hard link to the src file if requested
916 * but make sure we are not trying to overwrite ourselves.
919 res = cross_lnk(arcn);
921 res = chk_same(arcn);
923 if (vflag && vfpart) {
924 (void)putc('\n', listf);
931 * have to create a new file
933 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
935 * create a link or special file
937 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
938 res = lnk_creat(arcn);
940 res = node_creat(arcn);
943 if (vflag && vfpart) {
944 (void)putc('\n', listf);
951 * have to copy a regular file to the destination directory.
952 * first open source file and then create the destination file
954 if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
955 syswarn(1, errno, "Unable to open %s to read",
960 if ((fddest = file_creat(arcn)) < 0) {
961 rdfile_close(arcn, &fdsrc);
967 * copy source file data to the destination file
969 cp_file(arcn, fdsrc, fddest);
970 file_close(arcn, fddest);
971 rdfile_close(arcn, &fdsrc);
973 if (vflag && vfpart) {
974 (void)putc('\n', listf);
980 * restore directory modes and times as required; make sure all
981 * patterns were selected block off signals to avoid chance for
982 * multiple entry into the cleanup code.
984 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
992 * try to find a valid header in the archive. Uses format specific
993 * routines to extract the header and id the trailer. Trailers may be
994 * located within a valid header or in an invalid header (the location
995 * is format specific. The inhead field from the option table tells us
996 * where to look for the trailer).
997 * We keep reading (and resyncing) until we get enough contiguous data
998 * to check for a header. If we cannot find one, we shift by a byte
999 * add a new byte from the archive to the end of the buffer and try again.
1000 * If we get a read error, we throw out what we have (as we must have
1001 * contiguous data) and start over again.
1002 * ASSUMED: headers fit within a BLKMULT header.
1004 * 0 if we got a header, -1 if we are unable to ever find another one
1005 * (we reached the end of input, or we reached the limit on retries. see
1006 * the specs for rd_wrbuf() for more details)
1011 next_head(register ARCHD *arcn)
1015 register ARCHD *arcn;
1019 register char *hdend;
1021 register int shftsz;
1023 register int in_resync = 0; /* set when we are in resync mode */
1024 int cnt = 0; /* counter for trailer function */
1025 int first = 1; /* on 1st read, EOF isn't premature. */
1028 * set up initial conditions, we want a whole frmt->hsz block as we
1031 res = hsz = frmt->hsz;
1036 * keep looping until we get a contiguous FULL buffer
1037 * (frmt->hsz is the proper size)
1040 if ((ret = rd_wrbuf(hdend, res)) == res)
1044 * If we read 0 bytes (EOF) from an archive when we
1045 * expect to find a header, we have stepped upon
1046 * an archive without the customary block of zeroes
1047 * end marker. It's just stupid to error out on
1048 * them, so exit gracefully.
1050 if (first && ret == 0)
1055 * some kind of archive read problem, try to resync the
1056 * storage device, better give the user the bad news.
1058 if ((ret == 0) || (rd_sync() < 0)) {
1059 paxwarn(1,"Premature end of file on archive read");
1065 "Archive I/O error, cannot continue");
1068 paxwarn(1,"Archive I/O error. Trying to recover.");
1073 * oh well, throw it all out and start over
1080 * ok we have a contiguous buffer of the right size. Call the
1081 * format read routine. If this was not a valid header and this
1082 * format stores trailers outside of the header, call the
1083 * format specific trailer routine to check for a trailer. We
1084 * have to watch out that we do not mis-identify file data or
1085 * block padding as a header or trailer. Format specific
1086 * trailer functions must NOT check for the trailer while we
1087 * are running in resync mode. Some trailer functions may tell
1088 * us that this block cannot contain a valid header either, so
1089 * we then throw out the entire block and start over.
1091 if ((*frmt->rd)(arcn, hdbuf) == 0)
1094 if (!frmt->inhead) {
1096 * this format has trailers outside of valid headers
1098 if ((ret = (*frmt->trail)(hdbuf,in_resync,&cnt)) == 0){
1100 * valid trailer found, drain input as required
1108 * we are in resync and we were told to throw
1109 * the whole block out because none of the
1110 * bytes in this block can be used to form a
1120 * Brute force section.
1121 * not a valid header. We may be able to find a header yet. So
1122 * we shift over by one byte, and set up to read one byte at a
1123 * time from the archive and place it at the end of the buffer.
1124 * We will keep moving byte at a time until we find a header or
1125 * get a read error and have to start over.
1129 paxwarn(1,"Unable to append, archive header flaw");
1132 paxwarn(1,"Invalid header, starting valid header search.");
1135 memmove(hdbuf, hdbuf+1, shftsz);
1137 hdend = hdbuf + shftsz;
1141 * ok got a valid header, check for trailer if format encodes it in the
1142 * the header. NOTE: the parameters are different than trailer routines
1143 * which encode trailers outside of the header!
1145 if (frmt->inhead && ((*frmt->trail)(arcn) == 0)) {
1147 * valid trailer found, drain input as required
1159 * Figure out what format an archive is. Handles archive with flaws by
1160 * brute force searches for a legal header in any supported format. The
1161 * format id routines have to be careful to NOT mis-identify a format.
1162 * ASSUMED: headers fit within a BLKMULT header.
1164 * 0 if archive found -1 otherwise
1176 register int hdsz = 0;
1178 register int minhd = BLKMULT;
1183 * find the smallest header size in all archive formats and then set up
1184 * to read the archive.
1186 for (i = 0; ford[i] >= 0; ++i) {
1187 if (fsub[ford[i]].hsz < minhd)
1188 minhd = fsub[ford[i]].hsz;
1198 * fill the buffer with at least the smallest header
1200 i = rd_wrbuf(hdend, res);
1207 * if we cannot recover from a read error quit
1209 if ((i == 0) || (rd_sync() < 0))
1213 * when we get an error none of the data we already
1214 * have can be used to create a legal header (we just
1215 * got an error in the middle), so we throw it all out
1216 * and refill the buffer with fresh data.
1224 paxwarn(1,"Cannot identify format. Searching...");
1230 * we have at least the size of the smallest header in any
1231 * archive format. Look to see if we have a match. The array
1232 * ford[] is used to specify the header id order to reduce the
1233 * chance of incorrectly id'ing a valid header (some formats
1234 * may be subsets of each other and the order would then be
1237 for (i = 0; ford[i] >= 0; ++i) {
1238 if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
1240 frmt = &(fsub[ford[i]]);
1242 * yuck, to avoid slow special case code in the extract
1243 * routines, just push this header back as if it was
1244 * not seen. We have left extra space at start of the
1245 * buffer for this purpose. This is a bit ugly, but
1246 * adding all the special case code is far worse.
1253 * We have a flawed archive, no match. we start searching, but
1254 * we never allow additions to flawed archives
1259 paxwarn(1, "Cannot identify format. Searching...");
1264 * brute force search for a header that we can id.
1265 * we shift through byte at a time. this is slow, but we cannot
1266 * determine the nature of the flaw in the archive in a
1270 memmove(hdbuf, hdbuf+1, hdsz);
1271 res = BLKMULT - hdsz;
1272 hdend = hdbuf + hdsz;
1282 * we cannot find a header, bow, apologize and quit
1284 paxwarn(1, "Sorry, unable to determine archive format.");