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ar_subs.c

/*    $OpenBSD: ar_subs.c,v 1.14 1998/09/20 02:22:21 millert Exp $      */
/*    $NetBSD: ar_subs.c,v 1.5 1995/03/21 09:07:06 cgd Exp $      */

/*-
 * Copyright (c) 1992 Keith Muller.
 * Copyright (c) 1992, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Keith Muller of the University of California, San Diego.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)ar_subs.c     8.2 (Berkeley) 4/18/94";
#else
static char rcsid[] = "$OpenBSD: ar_subs.c,v 1.14 1998/09/20 02:22:21 millert Exp $";
#endif
#endif /* not lint */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <signal.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include "pax.h"
#include "extern.h"

static void wr_archive __P((register ARCHD *, int is_app));
static int get_arc __P((void));
static int next_head __P((register ARCHD *));
extern sigset_t s_mask;

/*
 * Routines which control the overall operation modes of pax as specified by
 * the user: list, append, read ...
 */

static char hdbuf[BLKMULT];         /* space for archive header on read */
u_long flcnt;                       /* number of files processed */

/*
 * list()
 *    list the contents of an archive which match user supplied pattern(s)
 *    (no pattern matches all).
 */

#ifdef __STDC__
void
list(void)
#else
void
list()
#endif
{
      register ARCHD *arcn;
      register int res;
      ARCHD archd;
      time_t now;

      arcn = &archd;
      /*
       * figure out archive type; pass any format specific options to the
       * archive option processing routine; call the format init routine. We
       * also save current time for ls_list() so we do not make a system
       * call for each file we need to print. If verbose (vflag) start up
       * the name and group caches.
       */
      if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
          ((*frmt->st_rd)() < 0))
            return;

      if (vflag && ((uidtb_start() < 0) || (gidtb_start() < 0)))
            return;

      now = time(NULL);

      /*
       * step through the archive until the format says it is done
       */
      while (next_head(arcn) == 0) {
            /*
             * check for pattern, and user specified options match.
             * When all patterns are matched we are done.
             */
            if ((res = pat_match(arcn)) < 0)
                  break;

            if ((res == 0) && (sel_chk(arcn) == 0)) {
                  /*
                   * pattern resulted in a selected file
                   */
                  if (pat_sel(arcn) < 0)
                        break;

                  /*
                   * modify the name as requested by the user if name
                   * survives modification, do a listing of the file
                   */
                  if ((res = mod_name(arcn)) < 0)
                        break;
                  if (res == 0)
                        ls_list(arcn, now, stdout);
            }

            /*
             * skip to next archive format header using values calculated
             * by the format header read routine
             */
            if (rd_skip(arcn->skip + arcn->pad) == 1)
                  break;
      }

      /*
       * all done, let format have a chance to cleanup, and make sure that
       * the patterns supplied by the user were all matched
       */
      (void)(*frmt->end_rd)();
      (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
      ar_close();
      pat_chk();
}

/*
 * extract()
 *    extract the member(s) of an archive as specified by user supplied
 *    pattern(s) (no patterns extracts all members)
 */

#ifdef __STDC__
void
extract(void)
#else
void
extract()
#endif
{
      register ARCHD *arcn;
      register int res;
      off_t cnt;
      ARCHD archd;
      struct stat sb;
      int fd;
      time_t now;

      arcn = &archd;
      /*
       * figure out archive type; pass any format specific options to the
       * archive option processing routine; call the format init routine;
       * start up the directory modification time and access mode database
       */
      if ((get_arc() < 0) || ((*frmt->options)() < 0) ||
          ((*frmt->st_rd)() < 0) || (dir_start() < 0))
            return;

      /*
       * When we are doing interactive rename, we store the mapping of names
       * so we can fix up hard links files later in the archive.
       */
      if (iflag && (name_start() < 0))
            return;

      now = time(NULL);

      /*
       * step through each entry on the archive until the format read routine
       * says it is done
       */
      while (next_head(arcn) == 0) {

            /*
             * check for pattern, and user specified options match. When
             * all the patterns are matched we are done
             */
            if ((res = pat_match(arcn)) < 0)
                  break;

            if ((res > 0) || (sel_chk(arcn) != 0)) {
                  /*
                   * file is not selected. skip past any file data and
                   * padding and go back for the next archive member
                   */
                  (void)rd_skip(arcn->skip + arcn->pad);
                  continue;
            }

            /*
             * with -u or -D only extract when the archive member is newer
             * than the file with the same name in the file system (nos
             * test of being the same type is required).
             * NOTE: this test is done BEFORE name modifications as
             * specified by pax. this operation can be confusing to the
             * user who might expect the test to be done on an existing
             * file AFTER the name mod. In honesty the pax spec is probably
             * flawed in this respect.
             */
            if ((uflag || Dflag) && ((lstat(arcn->name, &sb) == 0))) {
                  if (uflag && Dflag) {
                        if ((arcn->sb.st_mtime <= sb.st_mtime) &&
                            (arcn->sb.st_ctime <= sb.st_ctime)) {
                              (void)rd_skip(arcn->skip + arcn->pad);
                              continue;
                        }
                  } else if (Dflag) {
                        if (arcn->sb.st_ctime <= sb.st_ctime) {
                              (void)rd_skip(arcn->skip + arcn->pad);
                              continue;
                        }
                  } else if (arcn->sb.st_mtime <= sb.st_mtime) {
                        (void)rd_skip(arcn->skip + arcn->pad);
                        continue;
                  }
            }

            /*
             * this archive member is now been selected. modify the name.
             */
            if ((pat_sel(arcn) < 0) || ((res = mod_name(arcn)) < 0))
                  break;
            if (res > 0) {
                  /*
                   * a bad name mod, skip and purge name from link table
                   */
                  purg_lnk(arcn);
                  (void)rd_skip(arcn->skip + arcn->pad);
                  continue;
            }

            /*
             * Non standard -Y and -Z flag. When the exisiting file is
             * same age or newer skip
             */
            if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
                  if (Yflag && Zflag) {
                        if ((arcn->sb.st_mtime <= sb.st_mtime) &&
                            (arcn->sb.st_ctime <= sb.st_ctime)) {
                              (void)rd_skip(arcn->skip + arcn->pad);
                              continue;
                        }
                  } else if (Yflag) {
                        if (arcn->sb.st_ctime <= sb.st_ctime) {
                              (void)rd_skip(arcn->skip + arcn->pad);
                              continue;
                        }
                  } else if (arcn->sb.st_mtime <= sb.st_mtime) {
                        (void)rd_skip(arcn->skip + arcn->pad);
                        continue;
                  }
            }

            if (vflag) {
                  if (vflag > 1)
                        ls_list(arcn, now, listf);
                  else {
                        (void)fputs(arcn->name, listf);
                        vfpart = 1;
                  }
            }

            /*
             * if required, chdir around.
             */
            if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
                  if (chdir(arcn->pat->chdname) != 0)
                        syswarn(1, errno, "Cannot chdir to %s",
                            arcn->pat->chdname);

            /*
             * all ok, extract this member based on type
             */
            if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
                  /*
                   * process archive members that are not regular files.
                   * throw out padding and any data that might follow the
                   * header (as determined by the format).
                   */
                  if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
                        res = lnk_creat(arcn);
                  else
                        res = node_creat(arcn);

                  (void)rd_skip(arcn->skip + arcn->pad);
                  if (res < 0)
                        purg_lnk(arcn);

                  if (vflag && vfpart) {
                        (void)putc('\n', listf);
                        vfpart = 0;
                  }
                  continue;
            }
            /*
             * we have a file with data here. If we can not create it, skip
             * over the data and purge the name from hard link table
             */
            if ((fd = file_creat(arcn)) < 0) {
                  (void)rd_skip(arcn->skip + arcn->pad);
                  purg_lnk(arcn);
                  continue;
            }
            /*
             * extract the file from the archive and skip over padding and
             * any unprocessed data
             */
            res = (*frmt->rd_data)(arcn, fd, &cnt);
            file_close(arcn, fd);
            if (vflag && vfpart) {
                  (void)putc('\n', listf);
                  vfpart = 0;
            }
            if (!res)
                  (void)rd_skip(cnt + arcn->pad);

            /*
             * if required, chdir around.
             */
            if ((arcn->pat != NULL) && (arcn->pat->chdname != NULL))
                  if (fchdir(cwdfd) != 0)
                        syswarn(1, errno,
                            "Can't fchdir to starting directory");
      }

      /*
       * all done, restore directory modes and times as required; make sure
       * all patterns supplied by the user were matched; block off signals
       * to avoid chance for multiple entry into the cleanup code.
       */
      (void)(*frmt->end_rd)();
      (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
      ar_close();
      proc_dir();
      pat_chk();
}

/*
 * wr_archive()
 *    Write an archive. used in both creating a new archive and appends on
 *    previously written archive.
 */

#ifdef __STDC__
static void
wr_archive(register ARCHD *arcn, int is_app)
#else
static void
wr_archive(arcn, is_app)
      register ARCHD *arcn;
      int is_app;
#endif
{
      register int res;
      register int hlk;
      register int wr_one;
      off_t cnt;
      int (*wrf)();
      int fd = -1;
      time_t now;

      /*
       * if this format supports hard link storage, start up the database
       * that detects them.
       */
      if (((hlk = frmt->hlk) == 1) && (lnk_start() < 0))
            return;

      /*
       * start up the file traversal code and format specific write
       */
      if ((ftree_start() < 0) || ((*frmt->st_wr)() < 0))
            return;
      wrf = frmt->wr;

      /*
       * When we are doing interactive rename, we store the mapping of names
       * so we can fix up hard links files later in the archive.
       */
      if (iflag && (name_start() < 0))
            return;

      /*
       * if this not append, and there are no files, we do no write a trailer
       */
      wr_one = is_app;

      now = time(NULL);

      /*
       * while there are files to archive, process them one at at time
       */
      while (next_file(arcn) == 0) {
            /*
             * check if this file meets user specified options match.
             */
            if (sel_chk(arcn) != 0)
                  continue;
            fd = -1;
            if (uflag) {
                  /*
                   * only archive if this file is newer than a file with
                   * the same name that is already stored on the archive
                   */
                  if ((res = chk_ftime(arcn)) < 0)
                        break;
                  if (res > 0)
                        continue;
            }

            /*
             * this file is considered selected now. see if this is a hard
             * link to a file already stored
             */
            ftree_sel(arcn);
            if (hlk && (chk_lnk(arcn) < 0))
                  break;

            if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
                (arcn->type == PAX_CTG)) {
                  /*
                   * we will have to read this file. by opening it now we
                   * can avoid writing a header to the archive for a file
                   * we were later unable to read (we also purge it from
                   * the link table).
                   */
                  if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
                        syswarn(1,errno, "Unable to open %s to read",
                              arcn->org_name);
                        purg_lnk(arcn);
                        continue;
                  }
            }

            /*
             * Now modify the name as requested by the user
             */
            if ((res = mod_name(arcn)) < 0) {
                  /*
                   * name modification says to skip this file, close the
                   * file and purge link table entry
                   */
                  rdfile_close(arcn, &fd);
                  purg_lnk(arcn);
                  break;
            }

            if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
                  /*
                   * unable to obtain the crc we need, close the file,
                   * purge link table entry 
                   */
                  rdfile_close(arcn, &fd);
                  purg_lnk(arcn);
                  continue;
            }

            if (vflag) {
                  if (vflag > 1)
                        ls_list(arcn, now, listf);
                  else {
                        (void)fputs(arcn->name, listf);
                        vfpart = 1;
                  }
            }
            ++flcnt;

            /*
             * looks safe to store the file, have the format specific
             * routine write routine store the file header on the archive
             */
            if ((res = (*wrf)(arcn)) < 0) {
                  rdfile_close(arcn, &fd);
                  break;
            }
            wr_one = 1;
            if (res > 0) {
                  /* 
                   * format write says no file data needs to be stored
                   * so we are done messing with this file
                   */
                  if (vflag && vfpart) {
                        (void)putc('\n', listf);
                        vfpart = 0;
                  }
                  rdfile_close(arcn, &fd);
                  continue;
            }

            /*
             * Add file data to the archive, quit on write error. if we
             * cannot write the entire file contents to the archive we
             * must pad the archive to replace the missing file data
             * (otherwise during an extract the file header for the file
             * which FOLLOWS this one will not be where we expect it to
             * be).
             */
            res = (*frmt->wr_data)(arcn, fd, &cnt);
            rdfile_close(arcn, &fd);
            if (vflag && vfpart) {
                  (void)putc('\n', listf);
                  vfpart = 0;
            }
            if (res < 0)
                  break;

            /*
             * pad as required, cnt is number of bytes not written
             */
            if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
                ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
                  break;
      }

      /*
       * tell format to write trailer; pad to block boundry; reset directory
       * mode/access times, and check if all patterns supplied by the user
       * were matched. block off signals to avoid chance for multiple entry
       * into the cleanup code
       */
      if (wr_one) {
            (*frmt->end_wr)();
            wr_fin();
      }
      (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
      ar_close();
      if (tflag)
            proc_dir();
      ftree_chk();
}

/*
 * append()
 *    Add file to previously written archive. Archive format specified by the
 *    user must agree with archive. The archive is read first to collect
 *    modification times (if -u) and locate the archive trailer. The archive
 *    is positioned in front of the record with the trailer and wr_archive()
 *    is called to add the new members.
 *    PAX IMPLEMENTATION DETAIL NOTE:
 *    -u is implemented by adding the new members to the end of the archive.
 *    Care is taken so that these do not end up as links to the older 
 *    version of the same file already stored in the archive. It is expected
 *    when extraction occurs these newer versions will over-write the older
 *    ones stored "earlier" in the archive (this may be a bad assumption as
 *    it depends on the implementation of the program doing the extraction).
 *    It is really difficult to splice in members without either re-writing
 *    the entire archive (from the point were the old version was), or having
 *    assistance of the format specification in terms of a special update
 *    header that invalidates a previous archive record. The posix spec left
 *    the method used to implement -u unspecified. This pax is able to
 *    over write existing files that it creates.
 */

#ifdef __STDC__
void
append(void)
#else
void
append()
#endif
{
      register ARCHD *arcn;
      register int res;
      ARCHD archd;
      FSUB *orgfrmt;
      int udev;
      off_t tlen;

      arcn = &archd;
      orgfrmt = frmt;

      /*
       * Do not allow an append operation if the actual archive is of a
       * different format than the user specified foramt.
       */
      if (get_arc() < 0)
            return;
      if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
            paxwarn(1, "Cannot mix current archive format %s with %s",
                frmt->name, orgfrmt->name);
            return;
      }

      /*
       * pass the format any options and start up format
       */
      if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
            return;

      /*
       * if we only are adding members that are newer, we need to save the
       * mod times for all files we see.
       */
      if (uflag && (ftime_start() < 0))
            return;

      /*
       * some archive formats encode hard links by recording the device and
       * file serial number (inode) but copy the file anyway (multiple times)
       * to the archive. When we append, we run the risk that newly added
       * files may have the same device and inode numbers as those recorded
       * on the archive but during a previous run. If this happens, when the
       * archive is extracted we get INCORRECT hard links. We avoid this by
       * remapping the device numbers so that newly added files will never
       * use the same device number as one found on the archive. remapping
       * allows new members to safely have links among themselves. remapping
       * also avoids problems with file inode (serial number) truncations
       * when the inode number is larger than storage space in the archive
       * header. See the remap routines for more details.
       */
      if ((udev = frmt->udev) && (dev_start() < 0))
            return;

      /*
       * reading the archive may take a long time. If verbose tell the user
       */
      if (vflag) {
            (void)fprintf(listf,
                  "%s: Reading archive to position at the end...", argv0);
            vfpart = 1;
      }

      /*
       * step through the archive until the format says it is done
       */
      while (next_head(arcn) == 0) {
            /*
             * check if this file meets user specified options.
             */
            if (sel_chk(arcn) != 0) {
                  if (rd_skip(arcn->skip + arcn->pad) == 1)
                        break;
                  continue;
            }

            if (uflag) {
                  /*
                   * see if this is the newest version of this file has
                   * already been seen, if so skip.
                   */
                  if ((res = chk_ftime(arcn)) < 0)
                        break;
                  if (res > 0) {
                        if (rd_skip(arcn->skip + arcn->pad) == 1)
                              break;
                        continue;
                  }
            }

            /*
             * Store this device number. Device numbers seen during the
             * read phase of append will cause newly appended files with a
             * device number seen in the old part of the archive to be
             * remapped to an unused device number.
             */
            if ((udev && (add_dev(arcn) < 0)) ||
                (rd_skip(arcn->skip + arcn->pad) == 1))
                  break;
      }

      /*
       * done, finish up read and get the number of bytes to back up so we
       * can add new members. The format might have used the hard link table,
       * purge it.
       */
      tlen = (*frmt->end_rd)();
      lnk_end();

      /*
       * try to postion for write, if this fails quit. if any error occurs,
       * we will refuse to write
       */
      if (appnd_start(tlen) < 0)
            return;

      /*
       * tell the user we are done reading.
       */
      if (vflag && vfpart) {
            (void)fputs("done.\n", listf);
            vfpart = 0;
      }
       
      /*
       * go to the writing phase to add the new members
       */
      wr_archive(arcn, 1);
}

/*
 * archive()
 *    write a new archive
 */

#ifdef __STDC__
void
archive(void)
#else
void
archive()
#endif
{
      ARCHD archd;

      /*
       * if we only are adding members that are newer, we need to save the
       * mod times for all files; set up for writing; pass the format any
       * options write the archive
       */
      if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
            return;
      if ((*frmt->options)() < 0)
            return;

      wr_archive(&archd, 0);
}

/*
 * copy()
 *    copy files from one part of the file system to another. this does not
 *    use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
 *    archive was written and then extracted in the destination directory
 *    (except the files are forced to be under the destination directory).
 */

#ifdef __STDC__
void
copy(void)
#else
void
copy()
#endif
{
      register ARCHD *arcn;
      register int res;
      register int fddest;
      register char *dest_pt;
      register int dlen;
      register int drem;
      int fdsrc = -1;
      struct stat sb;
      ARCHD archd;
      char dirbuf[PAXPATHLEN+1];

      arcn = &archd;
      /*
       * set up the destination dir path and make sure it is a directory. We
       * make sure we have a trailing / on the destination
       */
      dlen = l_strncpy(dirbuf, dirptr, sizeof(dirbuf) - 1);
      dest_pt = dirbuf + dlen;
      if (*(dest_pt-1) != '/') {
            *dest_pt++ = '/';
            ++dlen;
      }
      *dest_pt = '\0';
      drem = PAXPATHLEN - dlen;

      if (stat(dirptr, &sb) < 0) {
            syswarn(1, errno, "Cannot access destination directory %s",
                  dirptr);
            return;
      }
      if (!S_ISDIR(sb.st_mode)) {
            paxwarn(1, "Destination is not a directory %s", dirptr);
            return;
      }

      /*
       * start up the hard link table; file traversal routines and the
       * modification time and access mode database 
       */
      if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
            return;

      /*
       * When we are doing interactive rename, we store the mapping of names
       * so we can fix up hard links files later in the archive.
       */
      if (iflag && (name_start() < 0))
            return;

      /*
       * set up to cp file trees
       */
      cp_start();

      /*
       * while there are files to archive, process them
       */
      while (next_file(arcn) == 0) {
            fdsrc = -1;

            /*
             * check if this file meets user specified options
             */
            if (sel_chk(arcn) != 0)
                  continue;

            /*
             * if there is already a file in the destination directory with
             * the same name and it is newer, skip the one stored on the
             * archive.
             * NOTE: this test is done BEFORE name modifications as
             * specified by pax. this can be confusing to the user who
             * might expect the test to be done on an existing file AFTER
             * the name mod. In honesty the pax spec is probably flawed in
             * this respect
             */
            if (uflag || Dflag) {
                  /*
                   * create the destination name
                   */
                  if (*(arcn->name) == '/')
                        res = 1;
                  else
                        res = 0;
                  if ((arcn->nlen - res) > drem) {
                        paxwarn(1, "Destination pathname too long %s",
                              arcn->name);
                        continue;
                  }
                  (void)strncpy(dest_pt, arcn->name + res, drem);
                  dirbuf[PAXPATHLEN] = '\0';

                  /*
                   * if existing file is same age or newer skip
                   */
                  res = lstat(dirbuf, &sb);
                  *dest_pt = '\0';

                  if (res == 0) {
                        if (uflag && Dflag) {
                              if ((arcn->sb.st_mtime<=sb.st_mtime) &&
                                  (arcn->sb.st_ctime<=sb.st_ctime))
                                    continue;
                        } else if (Dflag) {
                              if (arcn->sb.st_ctime <= sb.st_ctime)
                                    continue;
                        } else if (arcn->sb.st_mtime <= sb.st_mtime)
                              continue;
                  }
            }

            /*
             * this file is considered selected. See if this is a hard link
             * to a previous file; modify the name as requested by the
             * user; set the final destination.
             */
            ftree_sel(arcn);
            if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
                  break;
            if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
                  /*
                   * skip file, purge from link table
                   */
                  purg_lnk(arcn);
                  continue;
            }

            /*
             * Non standard -Y and -Z flag. When the exisiting file is
             * same age or newer skip
             */
            if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
                  if (Yflag && Zflag) {
                        if ((arcn->sb.st_mtime <= sb.st_mtime) &&
                            (arcn->sb.st_ctime <= sb.st_ctime))
                              continue;
                  } else if (Yflag) {
                        if (arcn->sb.st_ctime <= sb.st_ctime)
                              continue;
                  } else if (arcn->sb.st_mtime <= sb.st_mtime)
                        continue;
            }

            if (vflag) {
                  (void)fputs(arcn->name, listf);
                  vfpart = 1;
            }
            ++flcnt;

            /*
             * try to create a hard link to the src file if requested
             * but make sure we are not trying to overwrite ourselves.
             */
            if (lflag)
                  res = cross_lnk(arcn);
            else
                  res = chk_same(arcn);
            if (res <= 0) {
                  if (vflag && vfpart) {
                        (void)putc('\n', listf);
                        vfpart = 0;
                  }
                  continue;
            }

            /*
             * have to create a new file
             */
            if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
                  /*
                   * create a link or special file
                   */
                  if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
                        res = lnk_creat(arcn);
                  else
                        res = node_creat(arcn);
                  if (res < 0)
                        purg_lnk(arcn);
                  if (vflag && vfpart) {
                        (void)putc('\n', listf);
                        vfpart = 0;
                  }
                  continue;
            }

            /*
             * have to copy a regular file to the destination directory.
             * first open source file and then create the destination file
             */
            if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
                  syswarn(1, errno, "Unable to open %s to read",
                      arcn->org_name);
                  purg_lnk(arcn);
                  continue;
            }
            if ((fddest = file_creat(arcn)) < 0) {
                  rdfile_close(arcn, &fdsrc);
                  purg_lnk(arcn);
                  continue;
            }

            /*
             * copy source file data to the destination file
             */
            cp_file(arcn, fdsrc, fddest);
            file_close(arcn, fddest);
            rdfile_close(arcn, &fdsrc);

            if (vflag && vfpart) {
                  (void)putc('\n', listf);
                  vfpart = 0;
            }
      }

      /*
       * restore directory modes and times as required; make sure all
       * patterns were selected block off signals to avoid chance for
       * multiple entry into the cleanup code.
       */
      (void)sigprocmask(SIG_BLOCK, &s_mask, NULL);
      ar_close();
      proc_dir();
      ftree_chk();
}

/*
 * next_head()
 *    try to find a valid header in the archive. Uses format specific
 *    routines to extract the header and id the trailer. Trailers may be
 *    located within a valid header or in an invalid header (the location
 *    is format specific. The inhead field from the option table tells us
 *    where to look for the trailer).
 *    We keep reading (and resyncing) until we get enough contiguous data
 *    to check for a header. If we cannot find one, we shift by a byte
 *    add a new byte from the archive to the end of the buffer and try again.
 *    If we get a read error, we throw out what we have (as we must have
 *    contiguous data) and start over again.
 *    ASSUMED: headers fit within a BLKMULT header.
 * Return:
 *    0 if we got a header, -1 if we are unable to ever find another one
 *    (we reached the end of input, or we reached the limit on retries. see
 *    the specs for rd_wrbuf() for more details)
 */

#ifdef __STDC__
static int
next_head(register ARCHD *arcn)
#else
static int
next_head(arcn)
      register ARCHD *arcn;
#endif
{
      register int ret;
      register char *hdend;
      register int res;
      register int shftsz;
      register int hsz;
      register int in_resync = 0;   /* set when we are in resync mode */
      int cnt = 0;                  /* counter for trailer function */
      int first = 1;                /* on 1st read, EOF isn't premature. */

      /*
       * set up initial conditions, we want a whole frmt->hsz block as we
       * have no data yet.
       */
      res = hsz = frmt->hsz;
      hdend = hdbuf;
      shftsz = hsz - 1;
      for(;;) {
            /*
             * keep looping until we get a contiguous FULL buffer
             * (frmt->hsz is the proper size)
             */
            for (;;) {
                  if ((ret = rd_wrbuf(hdend, res)) == res)
                        break;

                  /*
                   * If we read 0 bytes (EOF) from an archive when we
                   * expect to find a header, we have stepped upon
                   * an archive without the customary block of zeroes
                   * end marker.  It's just stupid to error out on
                   * them, so exit gracefully.
                   */
                  if (first && ret == 0)
                        return(-1);
                  first = 0;

                  /*
                   * some kind of archive read problem, try to resync the
                   * storage device, better give the user the bad news.
                   */
                  if ((ret == 0) || (rd_sync() < 0)) {
                        paxwarn(1,"Premature end of file on archive read");
                        return(-1);
                  }
                  if (!in_resync) {
                        if (act == APPND) {
                              paxwarn(1,
                                "Archive I/O error, cannot continue");
                              return(-1);
                        }
                        paxwarn(1,"Archive I/O error. Trying to recover.");
                        ++in_resync;
                  }

                  /*
                   * oh well, throw it all out and start over
                   */
                  res = hsz;
                  hdend = hdbuf;
            }

            /*
             * ok we have a contiguous buffer of the right size. Call the
             * format read routine. If this was not a valid header and this
             * format stores trailers outside of the header, call the
             * format specific trailer routine to check for a trailer. We
             * have to watch out that we do not mis-identify file data or
             * block padding as a header or trailer. Format specific
             * trailer functions must NOT check for the trailer while we
             * are running in resync mode. Some trailer functions may tell
             * us that this block cannot contain a valid header either, so
             * we then throw out the entire block and start over.
             */
            if ((*frmt->rd)(arcn, hdbuf) == 0)
                  break;

            if (!frmt->inhead) {
                  /*
                   * this format has trailers outside of valid headers
                   */
                  if ((ret = (*frmt->trail)(hdbuf,in_resync,&cnt)) == 0){
                        /*
                         * valid trailer found, drain input as required
                         */
                        ar_drain();
                        return(-1);
                  }

                  if (ret == 1) {
                        /*
                         * we are in resync and we were told to throw
                         * the whole block out because none of the
                         * bytes in this block can be used to form a
                         * valid header
                         */
                        res = hsz;
                        hdend = hdbuf;
                        continue;
                  }
            }

            /*
             * Brute force section.
             * not a valid header. We may be able to find a header yet. So
             * we shift over by one byte, and set up to read one byte at a
             * time from the archive and place it at the end of the buffer.
             * We will keep moving byte at a time until we find a header or
             * get a read error and have to start over.
             */
            if (!in_resync) {
                  if (act == APPND) {
                        paxwarn(1,"Unable to append, archive header flaw");
                        return(-1);
                  }
                  paxwarn(1,"Invalid header, starting valid header search.");
                  ++in_resync;
            }
            memmove(hdbuf, hdbuf+1, shftsz);
            res = 1;
            hdend = hdbuf + shftsz;
      }

      /*
       * ok got a valid header, check for trailer if format encodes it in the
       * the header. NOTE: the parameters are different than trailer routines
       * which encode trailers outside of the header!
       */
      if (frmt->inhead && ((*frmt->trail)(arcn) == 0)) {
            /*
             * valid trailer found, drain input as required
             */
            ar_drain();
            return(-1);
      }

      ++flcnt;
      return(0);
}

/*
 * get_arc()
 *    Figure out what format an archive is. Handles archive with flaws by
 *    brute force searches for a legal header in any supported format. The
 *    format id routines have to be careful to NOT mis-identify a format.
 *    ASSUMED: headers fit within a BLKMULT header.
 * Return:
 *    0 if archive found -1 otherwise
 */

#ifdef __STDC__
static int
get_arc(void)
#else
static int
get_arc()
#endif
{
      register int i;
      register int hdsz = 0;
      register int res;
      register int minhd = BLKMULT;
      char *hdend;
      int notice = 0;

      /*
       * find the smallest header size in all archive formats and then set up
       * to read the archive.
       */
      for (i = 0; ford[i] >= 0; ++i) {
            if (fsub[ford[i]].hsz < minhd)
                  minhd = fsub[ford[i]].hsz;
      }
      if (rd_start() < 0)
            return(-1);
      res = BLKMULT;
      hdsz = 0;
      hdend = hdbuf;
      for(;;) {
            for (;;) {
                  /*
                   * fill the buffer with at least the smallest header
                   */
                  i = rd_wrbuf(hdend, res);
                  if (i > 0)
                        hdsz += i;
                  if (hdsz >= minhd)
                        break;

                  /*
                   * if we cannot recover from a read error quit
                   */
                  if ((i == 0) || (rd_sync() < 0))
                        goto out;

                  /*
                   * when we get an error none of the data we already
                   * have can be used to create a legal header (we just
                   * got an error in the middle), so we throw it all out
                   * and refill the buffer with fresh data.
                   */
                  res = BLKMULT;
                  hdsz = 0;
                  hdend = hdbuf;
                  if (!notice) {
                        if (act == APPND)
                              return(-1);
                        paxwarn(1,"Cannot identify format. Searching...");
                        ++notice;
                  }
            }

            /*
             * we have at least the size of the smallest header in any
             * archive format. Look to see if we have a match. The array
             * ford[] is used to specify the header id order to reduce the
             * chance of incorrectly id'ing a valid header (some formats
             * may be subsets of each other and the order would then be
             * important).
             */
            for (i = 0; ford[i] >= 0; ++i) {
                  if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
                        continue;
                  frmt = &(fsub[ford[i]]);
                  /* 
                   * yuck, to avoid slow special case code in the extract
                   * routines, just push this header back as if it was
                   * not seen. We have left extra space at start of the
                   * buffer for this purpose. This is a bit ugly, but
                   * adding all the special case code is far worse.
                   */
                  pback(hdbuf, hdsz);
                  return(0);
            }

            /*
             * We have a flawed archive, no match. we start searching, but
             * we never allow additions to flawed archives
             */
            if (!notice) {
                  if (act == APPND)
                        return(-1);
                  paxwarn(1, "Cannot identify format. Searching...");
                  ++notice;
            }

            /*
             * brute force search for a header that we can id.
             * we shift through byte at a time. this is slow, but we cannot
             * determine the nature of the flaw in the archive in a
             * portable manner
             */
            if (--hdsz > 0) {
                  memmove(hdbuf, hdbuf+1, hdsz);
                  res = BLKMULT - hdsz;
                  hdend = hdbuf + hdsz;
            } else {
                  res = BLKMULT;
                  hdend = hdbuf;
                  hdsz = 0;
            }
      }

    out:
      /*
       * we cannot find a header, bow, apologize and quit
       */
      paxwarn(1, "Sorry, unable to determine archive format.");
      return(-1);
}

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