2 * Copyright (c) 1992 Keith Muller.
3 * Copyright (c) 1992, 1993
4 * The Regents of the University of California. All rights reserved.
6 * This code is derived from software contributed to Berkeley by
7 * Keith Muller of the University of California, San Diego.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 static char sccsid[] = "@(#)ar_subs.c 8.2 (Berkeley) 4/18/94";
42 static const char rcsid[] =
43 "$FreeBSD: src/bin/pax/ar_subs.c,v 1.13.2.1 2001/08/01 05:03:11 obrien Exp $";
46 #include <sys/types.h>
59 static void wr_archive __P((register ARCHD *, int is_app));
60 static int get_arc __P((void));
61 static int next_head __P((register ARCHD *));
62 extern sigset_t s_mask;
65 * Routines which control the overall operation modes of pax as specified by
66 * the user: list, append, read ...
69 static char hdbuf[BLKMULT]; /* space for archive header on read */
70 u_long flcnt; /* number of files processed */
74 * list the contents of an archive which match user supplied pattern(s)
75 * (no pattern matches all).
93 * figure out archive type; pass any format specific options to the
94 * archive option processing routine; call the format init routine. We
95 * also save current time for ls_list() so we do not make a system
96 * call for each file we need to print. If verbose (vflag) start up
97 * the name and group caches.
99 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
100 ((*frmt->st_rd)() < 0))
103 if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
109 * step through the archive until the format says it is done
111 while (next_head(arcn) == 0) {
113 * check for pattern, and user specified options match.
114 * When all patterns are matched we are done.
116 if ((res = pat_match(arcn)) < 0)
119 if ((res == 0) && (sel_chk(arcn) == 0)) {
121 * pattern resulted in a selected file
123 if (pat_sel(arcn) < 0)
127 * modify the name as requested by the user if name
128 * survives modification, do a listing of the file
130 if ((res = mod_name(arcn)) < 0)
133 ls_list(arcn, now, stdout);
137 * skip to next archive format header using values calculated
138 * by the format header read routine
140 if (rd_skip(arcn->skip + arcn->pad) == 1)
145 * all done, let format have a chance to cleanup, and make sure that
146 * the patterns supplied by the user were all matched
148 (void)(*frmt->end_rd)();
149 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
156 * extract the member(s) of an archive as specified by user supplied
157 * pattern(s) (no patterns extracts all members)
168 register ARCHD *arcn;
178 * figure out archive type; pass any format specific options to the
179 * archive option processing routine; call the format init routine;
180 * start up the directory modification time and access mode database
182 if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
183 ((*frmt->st_rd)() < 0) || (dir_start() < 0))
187 * When we are doing interactive rename, we store the mapping of names
188 * so we can fix up hard links files later in the archive.
190 if (iflag && (name_start() < 0))
196 * step through each entry on the archive until the format read routine
199 while (next_head(arcn) == 0) {
202 * check for pattern, and user specified options match. When
203 * all the patterns are matched we are done
205 if ((res = pat_match(arcn)) < 0)
208 if ((res > 0) || (sel_chk(arcn) != 0)) {
210 * file is not selected. skip past any file data and
211 * padding and go back for the next archive member
213 (void)rd_skip(arcn->skip + arcn->pad);
218 * with -u or -D only extract when the archive member is newer
219 * than the file with the same name in the file system (nos
220 * test of being the same type is required).
221 * NOTE: this test is done BEFORE name modifications as
222 * specified by pax. this operation can be confusing to the
223 * user who might expect the test to be done on an existing
224 * file AFTER the name mod. In honesty the pax spec is probably
225 * flawed in this respect.
227 if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
228 if (uflag && Dflag) {
229 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
230 (arcn->sb.st_ctime <= sb.st_ctime)) {
231 (void)rd_skip(arcn->skip + arcn->pad);
235 if (arcn->sb.st_ctime <= sb.st_ctime) {
236 (void)rd_skip(arcn->skip + arcn->pad);
239 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
240 (void)rd_skip(arcn->skip + arcn->pad);
246 * this archive member is now been selected. modify the name.
248 if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
252 * a bad name mod, skip and purge name from link table
255 (void)rd_skip(arcn->skip + arcn->pad);
260 * Non standard -Y and -Z flag. When the existing file is
261 * same age or newer skip
263 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
264 if (Yflag && Zflag) {
265 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
266 (arcn->sb.st_ctime <= sb.st_ctime)) {
267 (void)rd_skip(arcn->skip + arcn->pad);
271 if (arcn->sb.st_ctime <= sb.st_ctime) {
272 (void)rd_skip(arcn->skip + arcn->pad);
275 } else if (arcn->sb.st_mtime <= sb.st_mtime) {
276 (void)rd_skip(arcn->skip + arcn->pad);
283 ls_list(arcn, now, listf);
285 (void)fputs(arcn->name, listf);
291 * if required, chdir around.
293 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
294 if (chdir(arcn->pat->chdname) != 0)
295 syswarn(1, errno, "Cannot chdir to %s",
299 * all ok, extract this member based on type
301 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
303 * process archive members that are not regular files.
304 * throw out padding and any data that might follow the
305 * header (as determined by the format).
307 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
308 res = lnk_creat(arcn);
310 res = node_creat(arcn);
312 (void)rd_skip(arcn->skip + arcn->pad);
316 if (vflag && vfpart) {
317 (void)putc('\n', listf);
323 * we have a file with data here. If we can not create it, skip
324 * over the data and purge the name from hard link table
326 if ((fd = file_creat(arcn)) < 0) {
327 (void)rd_skip(arcn->skip + arcn->pad);
332 * extract the file from the archive and skip over padding and
333 * any unprocessed data
335 res = (*frmt->rd_data)(arcn, fd, &cnt);
336 file_close(arcn, fd);
337 if (vflag && vfpart) {
338 (void)putc('\n', listf);
342 (void)rd_skip(cnt + arcn->pad);
345 * if required, chdir around.
347 if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
348 if (fchdir(cwdfd) != 0)
350 "Can't fchdir to starting directory");
354 * all done, restore directory modes and times as required; make sure
355 * all patterns supplied by the user were matched; block off signals
356 * to avoid chance for multiple entry into the cleanup code.
358 (void)(*frmt->end_rd)();
359 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
367 * Write an archive. used in both creating a new archive and appends on
368 * previously written archive.
373 wr_archive(register ARCHD *arcn, int is_app)
376 wr_archive(arcn, is_app)
377 register ARCHD *arcn;
390 * if this format supports hard link storage, start up the database
393 if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
397 * start up the file traversal code and format specific write
399 if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
404 * When we are doing interactive rename, we store the mapping of names
405 * so we can fix up hard links files later in the archive.
407 if (iflag && (name_start() < 0))
411 * if this not append, and there are no files, we do no write a trailer
418 * while there are files to archive, process them one at at time
420 while (next_file(arcn) == 0) {
422 * check if this file meets user specified options match.
424 if (sel_chk(arcn) != 0)
429 * only archive if this file is newer than a file with
430 * the same name that is already stored on the archive
432 if ((res = chk_ftime(arcn)) < 0)
439 * this file is considered selected now. see if this is a hard
440 * link to a file already stored
443 if (hlk && (chk_lnk(arcn) < 0))
446 if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
447 (arcn->type == PAX_CTG)) {
449 * we will have to read this file. by opening it now we
450 * can avoid writing a header to the archive for a file
451 * we were later unable to read (we also purge it from
454 if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
455 syswarn(1,errno, "Unable to open %s to read",
463 * Now modify the name as requested by the user
465 if ((res = mod_name(arcn)) < 0) {
467 * name modification says to skip this file, close the
468 * file and purge link table entry
470 rdfile_close(arcn, &fd);
475 if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
477 * unable to obtain the crc we need, close the file,
478 * purge link table entry
480 rdfile_close(arcn, &fd);
487 ls_list(arcn, now, listf);
489 (void)fputs(arcn->name, listf);
496 * looks safe to store the file, have the format specific
497 * routine write routine store the file header on the archive
499 if ((res = (*wrf)(arcn)) < 0) {
500 rdfile_close(arcn, &fd);
506 * format write says no file data needs to be stored
507 * so we are done messing with this file
509 if (vflag && vfpart) {
510 (void)putc('\n', listf);
513 rdfile_close(arcn, &fd);
518 * Add file data to the archive, quit on write error. if we
519 * cannot write the entire file contents to the archive we
520 * must pad the archive to replace the missing file data
521 * (otherwise during an extract the file header for the file
522 * which FOLLOWS this one will not be where we expect it to
525 res = (*frmt->wr_data)(arcn, fd, &cnt);
526 rdfile_close(arcn, &fd);
527 if (vflag && vfpart) {
528 (void)putc('\n', listf);
535 * pad as required, cnt is number of bytes not written
537 if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
538 ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
543 * tell format to write trailer; pad to block boundary; reset directory
544 * mode/access times, and check if all patterns supplied by the user
545 * were matched. block off signals to avoid chance for multiple entry
546 * into the cleanup code
552 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
561 * Add file to previously written archive. Archive format specified by the
562 * user must agree with archive. The archive is read first to collect
563 * modification times (if -u) and locate the archive trailer. The archive
564 * is positioned in front of the record with the trailer and wr_archive()
565 * is called to add the new members.
566 * PAX IMPLEMENTATION DETAIL NOTE:
567 * -u is implemented by adding the new members to the end of the archive.
568 * Care is taken so that these do not end up as links to the older
569 * version of the same file already stored in the archive. It is expected
570 * when extraction occurs these newer versions will over-write the older
571 * ones stored "earlier" in the archive (this may be a bad assumption as
572 * it depends on the implementation of the program doing the extraction).
573 * It is really difficult to splice in members without either re-writing
574 * the entire archive (from the point were the old version was), or having
575 * assistance of the format specification in terms of a special update
576 * header that invalidates a previous archive record. The POSIX spec left
577 * the method used to implement -u unspecified. This pax is able to
578 * over write existing files that it creates.
589 register ARCHD *arcn;
600 * Do not allow an append operation if the actual archive is of a
601 * different format than the user specified format.
605 if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
606 paxwarn(1, "Cannot mix current archive format %s with %s",
607 frmt->name, orgfrmt->name);
612 * pass the format any options and start up format
614 if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
618 * if we only are adding members that are newer, we need to save the
619 * mod times for all files we see.
621 if (uflag && (ftime_start() < 0))
625 * some archive formats encode hard links by recording the device and
626 * file serial number (inode) but copy the file anyway (multiple times)
627 * to the archive. When we append, we run the risk that newly added
628 * files may have the same device and inode numbers as those recorded
629 * on the archive but during a previous run. If this happens, when the
630 * archive is extracted we get INCORRECT hard links. We avoid this by
631 * remapping the device numbers so that newly added files will never
632 * use the same device number as one found on the archive. remapping
633 * allows new members to safely have links among themselves. remapping
634 * also avoids problems with file inode (serial number) truncations
635 * when the inode number is larger than storage space in the archive
636 * header. See the remap routines for more details.
638 if ((udev = frmt->udev) && (dev_start() < 0))
642 * reading the archive may take a long time. If verbose tell the user
646 "%s: Reading archive to position at the end...", argv0);
651 * step through the archive until the format says it is done
653 while (next_head(arcn) == 0) {
655 * check if this file meets user specified options.
657 if (sel_chk(arcn) != 0) {
658 if (rd_skip(arcn->skip + arcn->pad) == 1)
665 * see if this is the newest version of this file has
666 * already been seen, if so skip.
668 if ((res = chk_ftime(arcn)) < 0)
671 if (rd_skip(arcn->skip + arcn->pad) == 1)
678 * Store this device number. Device numbers seen during the
679 * read phase of append will cause newly appended files with a
680 * device number seen in the old part of the archive to be
681 * remapped to an unused device number.
683 if ((udev && (add_dev(arcn) < 0)) ||
684 (rd_skip(arcn->skip + arcn->pad) == 1))
689 * done, finish up read and get the number of bytes to back up so we
690 * can add new members. The format might have used the hard link table,
693 tlen = (*frmt->end_rd)();
697 * try to position for write, if this fails quit. if any error occurs,
698 * we will refuse to write
700 if (appnd_start(tlen) < 0)
704 * tell the user we are done reading.
706 if (vflag && vfpart) {
707 (void)fputs("done.\n", listf);
712 * go to the writing phase to add the new members
719 * write a new archive
733 * if we only are adding members that are newer, we need to save the
734 * mod times for all files; set up for writing; pass the format any
735 * options write the archive
737 if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
739 if ((*frmt->options)() < 0)
742 wr_archive(&archd, 0);
747 * copy files from one part of the file system to another. this does not
748 * use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
749 * archive was written and then extracted in the destination directory
750 * (except the files are forced to be under the destination directory).
761 register ARCHD *arcn;
764 register char *dest_pt;
770 char dirbuf[PAXPATHLEN+1];
774 * set up the destination dir path and make sure it is a directory. We
775 * make sure we have a trailing / on the destination
777 dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
778 dest_pt = dirbuf + dlen;
779 if (*(dest_pt-1) != '/') {
784 drem = PAXPATHLEN - dlen;
786 if (stat(dirptr, &sb) < 0) {
787 syswarn(1, errno, "Cannot access destination directory %s",
791 if (!S_ISDIR(sb.st_mode)) {
792 paxwarn(1, "Destination is not a directory %s", dirptr);
797 * start up the hard link table; file traversal routines and the
798 * modification time and access mode database
800 if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
804 * When we are doing interactive rename, we store the mapping of names
805 * so we can fix up hard links files later in the archive.
807 if (iflag && (name_start() < 0))
811 * set up to cp file trees
816 * while there are files to archive, process them
818 while (next_file(arcn) == 0) {
822 * check if this file meets user specified options
824 if (sel_chk(arcn) != 0)
828 * if there is already a file in the destination directory with
829 * the same name and it is newer, skip the one stored on the
831 * NOTE: this test is done BEFORE name modifications as
832 * specified by pax. this can be confusing to the user who
833 * might expect the test to be done on an existing file AFTER
834 * the name mod. In honesty the pax spec is probably flawed in
837 if (uflag || Dflag) {
839 * create the destination name
841 if (*(arcn->name) == '/')
845 if ((arcn->nlen - res) > drem) {
846 paxwarn(1, "Destination pathname too long %s",
850 (void)strncpy(dest_pt, arcn->name + res, drem);
851 dirbuf[PAXPATHLEN] = '\0';
854 * if existing file is same age or newer skip
856 res = lstat(dirbuf, &sb);
860 if (uflag && Dflag) {
861 if ((arcn->sb.st_mtime<=sb.st_mtime) &&
862 (arcn->sb.st_ctime<=sb.st_ctime))
865 if (arcn->sb.st_ctime <= sb.st_ctime)
867 } else if (arcn->sb.st_mtime <= sb.st_mtime)
873 * this file is considered selected. See if this is a hard link
874 * to a previous file; modify the name as requested by the
875 * user; set the final destination.
878 if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
880 if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
882 * skip file, purge from link table
889 * Non standard -Y and -Z flag. When the exisiting file is
890 * same age or newer skip
892 if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
893 if (Yflag && Zflag) {
894 if ((arcn->sb.st_mtime <= sb.st_mtime) &&
895 (arcn->sb.st_ctime <= sb.st_ctime))
898 if (arcn->sb.st_ctime <= sb.st_ctime)
900 } else if (arcn->sb.st_mtime <= sb.st_mtime)
905 (void)fputs(arcn->name, listf);
911 * try to create a hard link to the src file if requested
912 * but make sure we are not trying to overwrite ourselves.
915 res = cross_lnk(arcn);
917 res = chk_same(arcn);
919 if (vflag && vfpart) {
920 (void)putc('\n', listf);
927 * have to create a new file
929 if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
931 * create a link or special file
933 if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
934 res = lnk_creat(arcn);
936 res = node_creat(arcn);
939 if (vflag && vfpart) {
940 (void)putc('\n', listf);
947 * have to copy a regular file to the destination directory.
948 * first open source file and then create the destination file
950 if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
951 syswarn(1, errno, "Unable to open %s to read",
956 if ((fddest = file_creat(arcn)) < 0) {
957 rdfile_close(arcn, &fdsrc);
963 * copy source file data to the destination file
965 cp_file(arcn, fdsrc, fddest);
966 file_close(arcn, fddest);
967 rdfile_close(arcn, &fdsrc);
969 if (vflag && vfpart) {
970 (void)putc('\n', listf);
976 * restore directory modes and times as required; make sure all
977 * patterns were selected block off signals to avoid chance for
978 * multiple entry into the cleanup code.
980 (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
988 * try to find a valid header in the archive. Uses format specific
989 * routines to extract the header and id the trailer. Trailers may be
990 * located within a valid header or in an invalid header (the location
991 * is format specific. The inhead field from the option table tells us
992 * where to look for the trailer).
993 * We keep reading (and resyncing) until we get enough contiguous data
994 * to check for a header. If we cannot find one, we shift by a byte
995 * add a new byte from the archive to the end of the buffer and try again.
996 * If we get a read error, we throw out what we have (as we must have
997 * contiguous data) and start over again.
998 * ASSUMED: headers fit within a BLKMULT header.
1000 * 0 if we got a header, -1 if we are unable to ever find another one
1001 * (we reached the end of input, or we reached the limit on retries. see
1002 * the specs for rd_wrbuf() for more details)
1007 next_head(register ARCHD *arcn)
1011 register ARCHD *arcn;
1015 register char *hdend;
1017 register int shftsz;
1019 register int in_resync = 0; /* set when we are in resync mode */
1020 int cnt = 0; /* counter for trailer function */
1021 int first = 1; /* on 1st read, EOF isn't premature. */
1024 * set up initial conditions, we want a whole frmt->hsz block as we
1027 res = hsz = frmt->hsz;
1032 * keep looping until we get a contiguous FULL buffer
1033 * (frmt->hsz is the proper size)
1036 if ((ret = rd_wrbuf(hdend, res)) == res)
1040 * If we read 0 bytes (EOF) from an archive when we
1041 * expect to find a header, we have stepped upon
1042 * an archive without the customary block of zeroes
1043 * end marker. It's just stupid to error out on
1044 * them, so exit gracefully.
1046 if (first && ret == 0)
1051 * some kind of archive read problem, try to resync the
1052 * storage device, better give the user the bad news.
1054 if ((ret == 0) || (rd_sync() < 0)) {
1055 paxwarn(1,"Premature end of file on archive read");
1061 "Archive I/O error, cannot continue");
1064 paxwarn(1,"Archive I/O error. Trying to recover.");
1069 * oh well, throw it all out and start over
1076 * ok we have a contiguous buffer of the right size. Call the
1077 * format read routine. If this was not a valid header and this
1078 * format stores trailers outside of the header, call the
1079 * format specific trailer routine to check for a trailer. We
1080 * have to watch out that we do not mis-identify file data or
1081 * block padding as a header or trailer. Format specific
1082 * trailer functions must NOT check for the trailer while we
1083 * are running in resync mode. Some trailer functions may tell
1084 * us that this block cannot contain a valid header either, so
1085 * we then throw out the entire block and start over.
1087 if ((*frmt->rd)(arcn, hdbuf) == 0)
1090 if (!frmt->inhead) {
1092 * this format has trailers outside of valid headers
1094 if ((ret = (*frmt->trail)(hdbuf,in_resync,&cnt)) == 0){
1096 * valid trailer found, drain input as required
1104 * we are in resync and we were told to throw
1105 * the whole block out because none of the
1106 * bytes in this block can be used to form a
1116 * Brute force section.
1117 * not a valid header. We may be able to find a header yet. So
1118 * we shift over by one byte, and set up to read one byte at a
1119 * time from the archive and place it at the end of the buffer.
1120 * We will keep moving byte at a time until we find a header or
1121 * get a read error and have to start over.
1125 paxwarn(1,"Unable to append, archive header flaw");
1128 paxwarn(1,"Invalid header, starting valid header search.");
1131 memmove(hdbuf, hdbuf+1, shftsz);
1133 hdend = hdbuf + shftsz;
1137 * ok got a valid header, check for trailer if format encodes it in the
1138 * the header. NOTE: the parameters are different than trailer routines
1139 * which encode trailers outside of the header!
1141 if (frmt->inhead && ((*frmt->trail)(arcn) == 0)) {
1143 * valid trailer found, drain input as required
1155 * Figure out what format an archive is. Handles archive with flaws by
1156 * brute force searches for a legal header in any supported format. The
1157 * format id routines have to be careful to NOT mis-identify a format.
1158 * ASSUMED: headers fit within a BLKMULT header.
1160 * 0 if archive found -1 otherwise
1172 register int hdsz = 0;
1174 register int minhd = BLKMULT;
1179 * find the smallest header size in all archive formats and then set up
1180 * to read the archive.
1182 for (i = 0; ford[i] >= 0; ++i) {
1183 if (fsub[ford[i]].hsz < minhd)
1184 minhd = fsub[ford[i]].hsz;
1194 * fill the buffer with at least the smallest header
1196 i = rd_wrbuf(hdend, res);
1203 * if we cannot recover from a read error quit
1205 if ((i == 0) || (rd_sync() < 0))
1209 * when we get an error none of the data we already
1210 * have can be used to create a legal header (we just
1211 * got an error in the middle), so we throw it all out
1212 * and refill the buffer with fresh data.
1220 paxwarn(1,"Cannot identify format. Searching...");
1226 * we have at least the size of the smallest header in any
1227 * archive format. Look to see if we have a match. The array
1228 * ford[] is used to specify the header id order to reduce the
1229 * chance of incorrectly id'ing a valid header (some formats
1230 * may be subsets of each other and the order would then be
1233 for (i = 0; ford[i] >= 0; ++i) {
1234 if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
1236 frmt = &(fsub[ford[i]]);
1238 * yuck, to avoid slow special case code in the extract
1239 * routines, just push this header back as if it was
1240 * not seen. We have left extra space at start of the
1241 * buffer for this purpose. This is a bit ugly, but
1242 * adding all the special case code is far worse.
1249 * We have a flawed archive, no match. we start searching, but
1250 * we never allow additions to flawed archives
1255 paxwarn(1, "Cannot identify format. Searching...");
1260 * brute force search for a header that we can id.
1261 * we shift through byte at a time. this is slow, but we cannot
1262 * determine the nature of the flaw in the archive in a
1266 memmove(hdbuf, hdbuf+1, hdsz);
1267 res = BLKMULT - hdsz;
1268 hdend = hdbuf + hdsz;
1278 * we cannot find a header, bow, apologize and quit
1280 paxwarn(1, "Sorry, unable to determine archive format.");