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tar.c

/*    $OpenBSD: tar.c,v 1.13 1998/09/26 21:29:41 millert Exp $    */
/*    $NetBSD: tar.c,v 1.5 1995/03/21 09:07:49 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[] = "@(#)tar.c   8.2 (Berkeley) 4/18/94";
#else
static char rcsid[] = "$OpenBSD: tar.c,v 1.13 1998/09/26 21:29:41 millert Exp $";
#endif
#endif /* not lint */

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

/*
 * Routines for reading, writing and header identify of various versions of tar
 */

static u_long tar_chksm __P((register char *, register int));
static char *name_split __P((register char *, register int));
static int ul_oct __P((u_long, register char *, register int, int));
#ifndef NET2_STAT
static int uqd_oct __P((u_quad_t, register char *, register int, int));
#endif

/*
 * Routines common to all versions of tar
 */

static int tar_nodir;               /* do not write dirs under old tar */

/*
 * tar_endwr()
 *    add the tar trailer of two null blocks
 * Return:
 *    0 if ok, -1 otherwise (what wr_skip returns)
 */

#ifdef __STDC__
int
tar_endwr(void)
#else
int
tar_endwr()
#endif
{
      return(wr_skip((off_t)(NULLCNT*BLKMULT)));
}

/*
 * tar_endrd()
 *    no cleanup needed here, just return size of trailer (for append)
 * Return:
 *    size of trailer (2 * BLKMULT)
 */

#ifdef __STDC__
off_t
tar_endrd(void)
#else
off_t
tar_endrd()
#endif
{
      return((off_t)(NULLCNT*BLKMULT));
}

/*
 * tar_trail()
 *    Called to determine if a header block is a valid trailer. We are passed
 *    the block, the in_sync flag (which tells us we are in resync mode;
 *    looking for a valid header), and cnt (which starts at zero) which is
 *    used to count the number of empty blocks we have seen so far.
 * Return:
 *    0 if a valid trailer, -1 if not a valid trailer, or 1 if the block
 *    could never contain a header.
 */

#ifdef __STDC__
int
tar_trail(register char *buf, register int in_resync, register int *cnt)
#else
int
tar_trail(buf, in_resync, cnt)
      register char *buf;
      register int in_resync;
      register int *cnt;
#endif
{
      register int i;

      /*
       * look for all zero, trailer is two consecutive blocks of zero
       */
      for (i = 0; i < BLKMULT; ++i) {
            if (buf[i] != '\0')
                  break;
      }

      /*
       * if not all zero it is not a trailer, but MIGHT be a header.
       */
      if (i != BLKMULT)
            return(-1);

      /*
       * When given a zero block, we must be careful!
       * If we are not in resync mode, check for the trailer. Have to watch
       * out that we do not mis-identify file data as the trailer, so we do
       * NOT try to id a trailer during resync mode. During resync mode we
       * might as well throw this block out since a valid header can NEVER be
       * a block of all 0 (we must have a valid file name).
       */
      if (!in_resync && (++*cnt >= NULLCNT))
            return(0);
      return(1);
}

/*
 * ul_oct()
 *    convert an unsigned long to an octal string. many oddball field
 *    termination characters are used by the various versions of tar in the
 *    different fields. term selects which kind to use. str is '0' padded
 *    at the front to len. we are unable to use only one format as many old
 *    tar readers are very cranky about this.
 * Return:
 *    0 if the number fit into the string, -1 otherwise
 */

#ifdef __STDC__
static int
ul_oct(u_long val, register char *str, register int len, int term)
#else
static int
ul_oct(val, str, len, term)
      u_long val;
      register char *str;
      register int len;
      int term;
#endif
{
      register char *pt;

      /*
       * term selects the appropriate character(s) for the end of the string
       */
      pt = str + len - 1;
      switch(term) {
      case 3:
            *pt-- = '\0';
            break;
      case 2:
            *pt-- = ' ';
            *pt-- = '\0';
            break;
      case 1:
            *pt-- = ' ';
            break;
      case 0:
      default:
            *pt-- = '\0';
            *pt-- = ' ';
            break;
      }

      /*
       * convert and blank pad if there is space
       */
      while (pt >= str) {
            *pt-- = '0' + (char)(val & 0x7);
            if ((val = val >> 3) == (u_long)0)
                  break;
      }

      while (pt >= str)
            *pt-- = '0';
      if (val != (u_long)0)
            return(-1);
      return(0);
}

#ifndef NET2_STAT
/*
 * uqd_oct()
 *    convert an u_quad_t to an octal string. one of many oddball field
 *    termination characters are used by the various versions of tar in the
 *    different fields. term selects which kind to use. str is '0' padded
 *    at the front to len. we are unable to use only one format as many old
 *    tar readers are very cranky about this.
 * Return:
 *    0 if the number fit into the string, -1 otherwise
 */

#ifdef __STDC__
static int
uqd_oct(u_quad_t val, register char *str, register int len, int term)
#else
static int
uqd_oct(val, str, len, term)
      u_quad_t val;
      register char *str;
      register int len;
      int term;
#endif
{
      register char *pt;

      /*
       * term selects the appropriate character(s) for the end of the string
       */
      pt = str + len - 1;
      switch(term) {
      case 3:
            *pt-- = '\0';
            break;
      case 2:
            *pt-- = ' ';
            *pt-- = '\0';
            break;
      case 1:
            *pt-- = ' ';
            break;
      case 0:
      default:
            *pt-- = '\0';
            *pt-- = ' ';
            break;
      }

      /*
       * convert and blank pad if there is space
       */
      while (pt >= str) {
            *pt-- = '0' + (char)(val & 0x7);
            if ((val = val >> 3) == 0)
                  break;
      }

      while (pt >= str)
            *pt-- = '0';
      if (val != (u_quad_t)0)
            return(-1);
      return(0);
}
#endif

/*
 * tar_chksm()
 *    calculate the checksum for a tar block counting the checksum field as
 *    all blanks (BLNKSUM is that value pre-calculated, the sume of 8 blanks).
 *    NOTE: we use len to short circuit summing 0's on write since we ALWAYS
 *    pad headers with 0.
 * Return:
 *    unsigned long checksum
 */

#ifdef __STDC__
static u_long
tar_chksm(register char *blk, register int len)
#else
static u_long
tar_chksm(blk, len)
      register char *blk;
      register int len;
#endif
{
      register char *stop;
      register char *pt;
      u_long chksm = BLNKSUM; /* inital value is checksum field sum */

      /*
       * add the part of the block before the checksum field
       */
      pt = blk;
      stop = blk + CHK_OFFSET;
      while (pt < stop)
            chksm += (u_long)(*pt++ & 0xff);
      /*
       * move past the checksum field and keep going, spec counts the
       * checksum field as the sum of 8 blanks (which is pre-computed as
       * BLNKSUM).
       * ASSUMED: len is greater than CHK_OFFSET. (len is where our 0 padding
       * starts, no point in summing zero's)
       */
      pt += CHK_LEN;
      stop = blk + len;
      while (pt < stop)
            chksm += (u_long)(*pt++ & 0xff);
      return(chksm);
}

/*
 * Routines for old BSD style tar (also made portable to sysV tar)
 */

/*
 * tar_id()
 *    determine if a block given to us is a valid tar header (and not a USTAR
 *    header). We have to be on the lookout for those pesky blocks of   all
 *    zero's.
 * Return:
 *    0 if a tar header, -1 otherwise
 */

#ifdef __STDC__
int
tar_id(register char *blk, int size)
#else
int
tar_id(blk, size)
      register char *blk;
      int size;
#endif
{
      register HD_TAR *hd;
      register HD_USTAR *uhd;

      if (size < BLKMULT)
            return(-1);
      hd = (HD_TAR *)blk;
      uhd = (HD_USTAR *)blk;

      /*
       * check for block of zero's first, a simple and fast test, then make
       * sure this is not a ustar header by looking for the ustar magic
       * cookie. We should use TMAGLEN, but some USTAR archive programs are
       * wrong and create archives missing the \0. Last we check the
       * checksum. If this is ok we have to assume it is a valid header.
       */
      if (hd->name[0] == '\0')
            return(-1);
      if (strncmp(uhd->magic, TMAGIC, TMAGLEN - 1) == 0)
            return(-1);
      if (asc_ul(hd->chksum,sizeof(hd->chksum),OCT) != tar_chksm(blk,BLKMULT))
            return(-1);
      return(0);
}

/*
 * tar_opt()
 *    handle tar format specific -o options
 * Return:
 *    0 if ok -1 otherwise
 */

#ifdef __STDC__
int
tar_opt(void)
#else
int
tar_opt()
#endif
{
      OPLIST *opt;

      while ((opt = opt_next()) != NULL) {
            if (strcmp(opt->name, TAR_OPTION) ||
                strcmp(opt->value, TAR_NODIR)) {
                  paxwarn(1, "Unknown tar format -o option/value pair %s=%s",
                      opt->name, opt->value);
                  paxwarn(1,"%s=%s is the only supported tar format option",
                      TAR_OPTION, TAR_NODIR);
                  return(-1);
            }

            /*
             * we only support one option, and only when writing
             */
            if ((act != APPND) && (act != ARCHIVE)) {
                  paxwarn(1, "%s=%s is only supported when writing.",
                      opt->name, opt->value);
                  return(-1);
            }
            tar_nodir = 1;
      }
      return(0);
}


/*
 * tar_rd()
 *    extract the values out of block already determined to be a tar header.
 *    store the values in the ARCHD parameter.
 * Return:
 *    0
 */

#ifdef __STDC__
int
tar_rd(register ARCHD *arcn, register char *buf)
#else
int
tar_rd(arcn, buf)
      register ARCHD *arcn;
      register char *buf;
#endif
{
      register HD_TAR *hd;
      register char *pt;

      /*
       * we only get proper sized buffers passed to us
       */
      if (tar_id(buf, BLKMULT) < 0)
            return(-1);
      arcn->org_name = arcn->name;
      arcn->sb.st_nlink = 1;
      arcn->pat = NULL;

      /*
       * copy out the name and values in the stat buffer
       */
      hd = (HD_TAR *)buf;
      arcn->nlen = l_strncpy(arcn->name, hd->name, sizeof(arcn->name) - 1);
      arcn->name[arcn->nlen] = '\0';
      arcn->sb.st_mode = (mode_t)(asc_ul(hd->mode,sizeof(hd->mode),OCT) &
          0xfff);
      arcn->sb.st_uid = (uid_t)asc_ul(hd->uid, sizeof(hd->uid), OCT);
      arcn->sb.st_gid = (gid_t)asc_ul(hd->gid, sizeof(hd->gid), OCT);
      arcn->sb.st_size = (size_t)asc_ul(hd->size, sizeof(hd->size), OCT);
      arcn->sb.st_mtime = (time_t)asc_ul(hd->mtime, sizeof(hd->mtime), OCT);
      arcn->sb.st_ctime = arcn->sb.st_atime = arcn->sb.st_mtime;

      /*
       * have to look at the last character, it may be a '/' and that is used
       * to encode this as a directory
       */
      pt = &(arcn->name[arcn->nlen - 1]);
      arcn->pad = 0;
      arcn->skip = 0;
      switch(hd->linkflag) {
      case SYMTYPE:
            /*
             * symbolic link, need to get the link name and set the type in
             * the st_mode so -v printing will look correct.
             */
            arcn->type = PAX_SLK;
            arcn->ln_nlen = l_strncpy(arcn->ln_name, hd->linkname,
                  sizeof(arcn->ln_name) - 1);
            arcn->ln_name[arcn->ln_nlen] = '\0';
            arcn->sb.st_mode |= S_IFLNK;
            break;
      case LNKTYPE:
            /*
             * hard link, need to get the link name, set the type in the
             * st_mode and st_nlink so -v printing will look better.
             */
            arcn->type = PAX_HLK;
            arcn->sb.st_nlink = 2;
            arcn->ln_nlen = l_strncpy(arcn->ln_name, hd->linkname,
                  sizeof(arcn->ln_name) - 1);
            arcn->ln_name[arcn->ln_nlen] = '\0';

            /*
             * no idea of what type this thing really points at, but
             * we set something for printing only.
             */
            arcn->sb.st_mode |= S_IFREG;
            break;
      case DIRTYPE:
            /*
             * It is a directory, set the mode for -v printing
             */
            arcn->type = PAX_DIR;
            arcn->sb.st_mode |= S_IFDIR;
            arcn->sb.st_nlink = 2;
            arcn->ln_name[0] = '\0';
            arcn->ln_nlen = 0;
            break;
      case AREGTYPE:
      case REGTYPE:
      default:
            /*
             * If we have a trailing / this is a directory and NOT a file.
             */
            arcn->ln_name[0] = '\0';
            arcn->ln_nlen = 0;
            if (*pt == '/') {
                  /*
                   * it is a directory, set the mode for -v printing
                   */
                  arcn->type = PAX_DIR;
                  arcn->sb.st_mode |= S_IFDIR;
                  arcn->sb.st_nlink = 2;
            } else {
                  /*
                   * have a file that will be followed by data. Set the
                   * skip value to the size field and caluculate the size
                   * of the padding.
                   */
                  arcn->type = PAX_REG;
                  arcn->sb.st_mode |= S_IFREG;
                  arcn->pad = TAR_PAD(arcn->sb.st_size);
                  arcn->skip = arcn->sb.st_size;
            }
            break;
      }

      /*
       * strip off any trailing slash.
       */
      if (*pt == '/') {
            *pt = '\0'; 
            --arcn->nlen;
      }
      return(0);
}

/*
 * tar_wr()
 *    write a tar header for the file specified in the ARCHD to the archive.
 *    Have to check for file types that cannot be stored and file names that
 *    are too long. Be careful of the term (last arg) to ul_oct, each field
 *    of tar has it own spec for the termination character(s).
 *    ASSUMED: space after header in header block is zero filled
 * Return:
 *    0 if file has data to be written after the header, 1 if file has NO
 *    data to write after the header, -1 if archive write failed
 */

#ifdef __STDC__
int
tar_wr(register ARCHD *arcn)
#else
int
tar_wr(arcn)
      register ARCHD *arcn;
#endif
{
      register HD_TAR *hd;
      int len;
      char hdblk[sizeof(HD_TAR)];

      /*
       * check for those file system types which tar cannot store
       */
      switch(arcn->type) {
      case PAX_DIR:
            /*
             * user asked that dirs not be written to the archive
             */
            if (tar_nodir)
                  return(1);
            break;
      case PAX_CHR:
            paxwarn(1, "Tar cannot archive a character device %s",
                arcn->org_name);
            return(1);
      case PAX_BLK:
            paxwarn(1, "Tar cannot archive a block device %s", arcn->org_name);
            return(1);
      case PAX_SCK:
            paxwarn(1, "Tar cannot archive a socket %s", arcn->org_name);
            return(1);
      case PAX_FIF:
            paxwarn(1, "Tar cannot archive a fifo %s", arcn->org_name);
            return(1);
      case PAX_SLK:
      case PAX_HLK:
      case PAX_HRG:
            if (arcn->ln_nlen > sizeof(hd->linkname)) {
                  paxwarn(1,"Link name too long for tar %s", arcn->ln_name);
                  return(1);
            }
            break;
      case PAX_REG:
      case PAX_CTG:
      default:
            break;
      }

      /*
       * check file name len, remember extra char for dirs (the / at the end)
       */
      len = arcn->nlen;
      if (arcn->type == PAX_DIR)
            ++len;
      if (len >= sizeof(hd->name)) {
            paxwarn(1, "File name too long for tar %s", arcn->name);
            return(1);
      }

      /*
       * copy the data out of the ARCHD into the tar header based on the type
       * of the file. Remember many tar readers want the unused fields to be
       * padded with zero. We set the linkflag field (type), the linkname
       * (or zero if not used),the size, and set the padding (if any) to be
       * added after the file data (0 for all other types, as they only have
       * a header)
       */
      hd = (HD_TAR *)hdblk;
      l_strncpy(hd->name, arcn->name, sizeof(hd->name) - 1);
      hd->name[sizeof(hd->name) - 1] = '\0';
      arcn->pad = 0;

      if (arcn->type == PAX_DIR) {
            /*
             * directories are the same as files, except have a filename
             * that ends with a /, we add the slash here. No data follows,
             * dirs, so no pad.
             */
            hd->linkflag = AREGTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
            hd->name[len-1] = '/';
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 1))
                  goto out;
      } else if (arcn->type == PAX_SLK) {
            /*
             * no data follows this file, so no pad
             */
            hd->linkflag = SYMTYPE;
            l_strncpy(hd->linkname,arcn->ln_name, sizeof(hd->linkname) - 1);
            hd->linkname[sizeof(hd->linkname) - 1] = '\0';
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 1))
                  goto out;
      } else if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG)) {
            /*
             * no data follows this file, so no pad
             */
            hd->linkflag = LNKTYPE;
            l_strncpy(hd->linkname,arcn->ln_name, sizeof(hd->linkname) - 1);
            hd->linkname[sizeof(hd->linkname) - 1] = '\0';
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 1))
                  goto out;
      } else {
            /*
             * data follows this file, so set the pad
             */
            hd->linkflag = AREGTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
#           ifdef NET2_STAT
            if (ul_oct((u_long)arcn->sb.st_size, hd->size,
                sizeof(hd->size), 1)) {
#           else
            if (uqd_oct((u_quad_t)arcn->sb.st_size, hd->size,
                sizeof(hd->size), 1)) {
#           endif
                  paxwarn(1,"File is too large for tar %s", arcn->org_name);
                  return(1);
            }
            arcn->pad = TAR_PAD(arcn->sb.st_size);
      }

      /*
       * copy those fields that are independent of the type
       */
      if (ul_oct((u_long)arcn->sb.st_mode, hd->mode, sizeof(hd->mode), 0) ||
          ul_oct((u_long)arcn->sb.st_uid, hd->uid, sizeof(hd->uid), 0) ||
          ul_oct((u_long)arcn->sb.st_gid, hd->gid, sizeof(hd->gid), 0) ||
          ul_oct((u_long)arcn->sb.st_mtime, hd->mtime, sizeof(hd->mtime), 1))
            goto out;

      /*
       * calculate and add the checksum, then write the header. A return of
       * 0 tells the caller to now write the file data, 1 says no data needs
       * to be written
       */
      if (ul_oct(tar_chksm(hdblk, sizeof(HD_TAR)), hd->chksum,
          sizeof(hd->chksum), 3))
            goto out;
      if (wr_rdbuf(hdblk, sizeof(HD_TAR)) < 0)
            return(-1);
      if (wr_skip((off_t)(BLKMULT - sizeof(HD_TAR))) < 0)
            return(-1);
      if ((arcn->type == PAX_CTG) || (arcn->type == PAX_REG))
            return(0);
      return(1);

    out:
      /*
       * header field is out of range
       */
      paxwarn(1, "Tar header field is too small for %s", arcn->org_name);
      return(1);
}

/*
 * Routines for POSIX ustar
 */

/*
 * ustar_strd()
 *    initialization for ustar read
 * Return:
 *    0 if ok, -1 otherwise
 */

#ifdef __STDC__
int
ustar_strd(void)
#else
int
ustar_strd()
#endif
{
      if ((usrtb_start() < 0) || (grptb_start() < 0))
            return(-1);
      return(0);
}

/*
 * ustar_stwr()
 *    initialization for ustar write
 * Return:
 *    0 if ok, -1 otherwise
 */

#ifdef __STDC__
int
ustar_stwr(void)
#else
int
ustar_stwr()
#endif
{
      if ((uidtb_start() < 0) || (gidtb_start() < 0))
            return(-1);
      return(0);
}

/*
 * ustar_id()
 *    determine if a block given to us is a valid ustar header. We have to
 *    be on the lookout for those pesky blocks of all zero's
 * Return:
 *    0 if a ustar header, -1 otherwise
 */

#ifdef __STDC__
int
ustar_id(char *blk, int size)
#else
int
ustar_id(blk, size)
      char *blk;
      int size;
#endif
{
      register HD_USTAR *hd;

      if (size < BLKMULT)
            return(-1);
      hd = (HD_USTAR *)blk;

      /*
       * check for block of zero's first, a simple and fast test then check
       * ustar magic cookie. We should use TMAGLEN, but some USTAR archive
       * programs are fouled up and create archives missing the \0. Last we
       * check the checksum. If ok we have to assume it is a valid header.
       */
      if (hd->name[0] == '\0')
            return(-1);
      if (strncmp(hd->magic, TMAGIC, TMAGLEN - 1) != 0)
            return(-1);
      if (asc_ul(hd->chksum,sizeof(hd->chksum),OCT) != tar_chksm(blk,BLKMULT))
            return(-1);
      return(0);
}

/*
 * ustar_rd()
 *    extract the values out of block already determined to be a ustar header.
 *    store the values in the ARCHD parameter.
 * Return:
 *    0
 */

#ifdef __STDC__
int
ustar_rd(register ARCHD *arcn, register char *buf)
#else
int
ustar_rd(arcn, buf)
      register ARCHD *arcn;
      register char *buf;
#endif
{
      register HD_USTAR *hd;
      register char *dest;
      register int cnt = 0;
      dev_t devmajor;
      dev_t devminor;

      /*
       * we only get proper sized buffers
       */
      if (ustar_id(buf, BLKMULT) < 0)
            return(-1);
      arcn->org_name = arcn->name;
      arcn->sb.st_nlink = 1;
      arcn->pat = NULL;
      arcn->nlen = 0;
      hd = (HD_USTAR *)buf;

      /*
       * see if the filename is split into two parts. if, so joint the parts.
       * we copy the prefix first and add a / between the prefix and name.
       */
      dest = arcn->name;
      if (*(hd->prefix) != '\0') {
            cnt = l_strncpy(dest, hd->prefix, sizeof(arcn->name) - 2);
            dest += cnt;
            *dest++ = '/';
            cnt++;
      }
      arcn->nlen = cnt + l_strncpy(dest, hd->name, sizeof(arcn->name) - cnt);
      arcn->name[arcn->nlen] = '\0';

      /*
       * follow the spec to the letter. we should only have mode bits, strip
       * off all other crud we may be passed.
       */
      arcn->sb.st_mode = (mode_t)(asc_ul(hd->mode, sizeof(hd->mode), OCT) &
          0xfff);
      arcn->sb.st_size = (size_t)asc_ul(hd->size, sizeof(hd->size), OCT);
      arcn->sb.st_mtime = (time_t)asc_ul(hd->mtime, sizeof(hd->mtime), OCT);
      arcn->sb.st_ctime = arcn->sb.st_atime = arcn->sb.st_mtime;

      /*
       * If we can find the ascii names for gname and uname in the password
       * and group files we will use the uid's and gid they bind. Otherwise
       * we use the uid and gid values stored in the header. (This is what
       * the posix spec wants).
       */
      hd->gname[sizeof(hd->gname) - 1] = '\0';
      if (gid_name(hd->gname, &(arcn->sb.st_gid)) < 0)
            arcn->sb.st_gid = (gid_t)asc_ul(hd->gid, sizeof(hd->gid), OCT);
      hd->uname[sizeof(hd->uname) - 1] = '\0';
      if (uid_name(hd->uname, &(arcn->sb.st_uid)) < 0)
            arcn->sb.st_uid = (uid_t)asc_ul(hd->uid, sizeof(hd->uid), OCT);

      /*
       * set the defaults, these may be changed depending on the file type
       */
      arcn->ln_name[0] = '\0';
      arcn->ln_nlen = 0;
      arcn->pad = 0;
      arcn->skip = 0;
      arcn->sb.st_rdev = (dev_t)0;

      /*
       * set the mode and PAX type according to the typeflag in the header
       */
      switch(hd->typeflag) {
      case FIFOTYPE:
            arcn->type = PAX_FIF;
            arcn->sb.st_mode |= S_IFIFO;
            break;
      case DIRTYPE:
            arcn->type = PAX_DIR;
            arcn->sb.st_mode |= S_IFDIR;
            arcn->sb.st_nlink = 2;

            /*
             * Some programs that create ustar archives append a '/'
             * to the pathname for directories. This clearly violates
             * ustar specs, but we will silently strip it off anyway.
             */
            if (arcn->name[arcn->nlen - 1] == '/')
                  arcn->name[--arcn->nlen] = '\0';
            break;
      case BLKTYPE:
      case CHRTYPE:
            /*
             * this type requires the rdev field to be set.
             */
            if (hd->typeflag == BLKTYPE) {
                  arcn->type = PAX_BLK;
                  arcn->sb.st_mode |= S_IFBLK;
            } else {
                  arcn->type = PAX_CHR;
                  arcn->sb.st_mode |= S_IFCHR;
            }
            devmajor = (dev_t)asc_ul(hd->devmajor,sizeof(hd->devmajor),OCT);
            devminor = (dev_t)asc_ul(hd->devminor,sizeof(hd->devminor),OCT);
            arcn->sb.st_rdev = TODEV(devmajor, devminor);
            break;
      case SYMTYPE:
      case LNKTYPE:
            if (hd->typeflag == SYMTYPE) {
                  arcn->type = PAX_SLK;
                  arcn->sb.st_mode |= S_IFLNK;
            } else {
                  arcn->type = PAX_HLK;
                  /*
                   * so printing looks better
                   */
                  arcn->sb.st_mode |= S_IFREG;
                  arcn->sb.st_nlink = 2;
            }
            /*
             * copy the link name
             */
            arcn->ln_nlen = l_strncpy(arcn->ln_name, hd->linkname,
                  sizeof(arcn->ln_name) - 1);
            arcn->ln_name[arcn->ln_nlen] = '\0';
            break;
      case CONTTYPE:
      case AREGTYPE:
      case REGTYPE:
      default:
            /*
             * these types have file data that follows. Set the skip and
             * pad fields.
             */
            arcn->type = PAX_REG;
            arcn->pad = TAR_PAD(arcn->sb.st_size);
            arcn->skip = arcn->sb.st_size;
            arcn->sb.st_mode |= S_IFREG;
            break;
      }
      return(0);
}

/*
 * ustar_wr()
 *    write a ustar header for the file specified in the ARCHD to the archive
 *    Have to check for file types that cannot be stored and file names that
 *    are too long. Be careful of the term (last arg) to ul_oct, we only use
 *    '\0' for the termination character (this is different than picky tar)
 *    ASSUMED: space after header in header block is zero filled
 * Return:
 *    0 if file has data to be written after the header, 1 if file has NO
 *    data to write after the header, -1 if archive write failed
 */

#ifdef __STDC__
int
ustar_wr(register ARCHD *arcn)
#else
int
ustar_wr(arcn)
      register ARCHD *arcn;
#endif
{
      register HD_USTAR *hd;
      register char *pt;
      char hdblk[sizeof(HD_USTAR)];

      /*
       * check for those file system types ustar cannot store
       */
      if (arcn->type == PAX_SCK) {
            paxwarn(1, "Ustar cannot archive a socket %s", arcn->org_name);
            return(1);
      }

      /*
       * check the length of the linkname
       */
      if (((arcn->type == PAX_SLK) || (arcn->type == PAX_HLK) ||
          (arcn->type == PAX_HRG)) && (arcn->ln_nlen > sizeof(hd->linkname))){
            paxwarn(1, "Link name too long for ustar %s", arcn->ln_name);
            return(1);
      }

      /*
       * split the path name into prefix and name fields (if needed). if
       * pt != arcn->name, the name has to be split
       */
      if ((pt = name_split(arcn->name, arcn->nlen)) == NULL) {
            paxwarn(1, "File name too long for ustar %s", arcn->name);
            return(1);
      }
      hd = (HD_USTAR *)hdblk;
      arcn->pad = 0L;

      /*
       * split the name, or zero out the prefix
       */
      if (pt != arcn->name) {
            /*
             * name was split, pt points at the / where the split is to
             * occur, we remove the / and copy the first part to the prefix
             */
            *pt = '\0';
            l_strncpy(hd->prefix, arcn->name, sizeof(hd->prefix) - 1);
            *pt++ = '/';
      } else
            memset(hd->prefix, 0, sizeof(hd->prefix));

      /*
       * copy the name part. this may be the whole path or the part after
       * the prefix
       */
      l_strncpy(hd->name, pt, sizeof(hd->name) - 1);
      hd->name[sizeof(hd->name) - 1] = '\0';

      /*
       * set the fields in the header that are type dependent
       */
      switch(arcn->type) {
      case PAX_DIR:
            hd->typeflag = DIRTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
            memset(hd->devmajor, 0, sizeof(hd->devmajor));
            memset(hd->devminor, 0, sizeof(hd->devminor));
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 3))
                  goto out;
            break;
      case PAX_CHR:
      case PAX_BLK:
            if (arcn->type == PAX_CHR)
                  hd->typeflag = CHRTYPE;
            else
                  hd->typeflag = BLKTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
            if (ul_oct((u_long)MAJOR(arcn->sb.st_rdev), hd->devmajor,
               sizeof(hd->devmajor), 3) ||
               ul_oct((u_long)MINOR(arcn->sb.st_rdev), hd->devminor,
               sizeof(hd->devminor), 3) ||
               ul_oct((u_long)0L, hd->size, sizeof(hd->size), 3))
                  goto out;
            break;
      case PAX_FIF:
            hd->typeflag = FIFOTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
            memset(hd->devmajor, 0, sizeof(hd->devmajor));
            memset(hd->devminor, 0, sizeof(hd->devminor));
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 3))
                  goto out;
            break;
      case PAX_SLK:
      case PAX_HLK:
      case PAX_HRG:
            if (arcn->type == PAX_SLK)
                  hd->typeflag = SYMTYPE;
            else
                  hd->typeflag = LNKTYPE;
            l_strncpy(hd->linkname,arcn->ln_name, sizeof(hd->linkname) - 1);
            hd->linkname[sizeof(hd->linkname) - 1] = '\0';
            memset(hd->devmajor, 0, sizeof(hd->devmajor));
            memset(hd->devminor, 0, sizeof(hd->devminor));
            if (ul_oct((u_long)0L, hd->size, sizeof(hd->size), 3))
                  goto out;
            break;
      case PAX_REG:
      case PAX_CTG:
      default:
            /*
             * file data with this type, set the padding
             */
            if (arcn->type == PAX_CTG)
                  hd->typeflag = CONTTYPE;
            else
                  hd->typeflag = REGTYPE;
            memset(hd->linkname, 0, sizeof(hd->linkname));
            memset(hd->devmajor, 0, sizeof(hd->devmajor));
            memset(hd->devminor, 0, sizeof(hd->devminor));
            arcn->pad = TAR_PAD(arcn->sb.st_size);
#           ifdef NET2_STAT
            if (ul_oct((u_long)arcn->sb.st_size, hd->size,
                sizeof(hd->size), 3)) {
#           else
            if (uqd_oct((u_quad_t)arcn->sb.st_size, hd->size,
                sizeof(hd->size), 3)) {
#           endif
                  paxwarn(1,"File is too long for ustar %s",arcn->org_name);
                  return(1);
            }
            break;
      }

      l_strncpy(hd->magic, TMAGIC, TMAGLEN);
      l_strncpy(hd->version, TVERSION, TVERSLEN);

      /*
       * set the remaining fields. Some versions want all 16 bits of mode
       * we better humor them (they really do not meet spec though)....
       */
      if (ul_oct((u_long)arcn->sb.st_mode, hd->mode, sizeof(hd->mode), 3) ||
          ul_oct((u_long)arcn->sb.st_uid, hd->uid, sizeof(hd->uid), 3)  ||
          ul_oct((u_long)arcn->sb.st_gid, hd->gid, sizeof(hd->gid), 3) ||
          ul_oct((u_long)arcn->sb.st_mtime,hd->mtime,sizeof(hd->mtime),3))
            goto out;
      l_strncpy(hd->uname,name_uid(arcn->sb.st_uid, 0),sizeof(hd->uname));
      l_strncpy(hd->gname,name_gid(arcn->sb.st_gid, 0),sizeof(hd->gname));

      /*
       * calculate and store the checksum write the header to the archive
       * return 0 tells the caller to now write the file data, 1 says no data
       * needs to be written
       */
      if (ul_oct(tar_chksm(hdblk, sizeof(HD_USTAR)), hd->chksum,
         sizeof(hd->chksum), 3))
            goto out;
      if (wr_rdbuf(hdblk, sizeof(HD_USTAR)) < 0)
            return(-1);
      if (wr_skip((off_t)(BLKMULT - sizeof(HD_USTAR))) < 0)
            return(-1);
      if ((arcn->type == PAX_CTG) || (arcn->type == PAX_REG))
            return(0);
      return(1);

    out:
      /*
       * header field is out of range
       */
      paxwarn(1, "Ustar header field is too small for %s", arcn->org_name);
      return(1);
}

/*
 * name_split()
 *    see if the name has to be split for storage in a ustar header. We try
 *    to fit the entire name in the name field without splitting if we can.
 *    The split point is always at a /
 * Return
 *    character pointer to split point (always the / that is to be removed
 *    if the split is not needed, the points is set to the start of the file
 *    name (it would violate the spec to split there). A NULL is returned if
 *    the file name is too long
 */

#ifdef __STDC__
static char *
name_split(register char *name, register int len)
#else
static char *
name_split(name, len)
      register char *name;
      register int len;
#endif
{
      register char *start;

      /*
       * check to see if the file name is small enough to fit in the name
       * field. if so just return a pointer to the name.
       */
      if (len < TNMSZ)
            return(name);
      if (len > (TPFSZ + TNMSZ + 1))
            return(NULL);

      /*
       * we start looking at the biggest sized piece that fits in the name
       * field. We walk foward looking for a slash to split at. The idea is
       * to find the biggest piece to fit in the name field (or the smallest
       * prefix we can find) (the -1 is correct the biggest piece would
       * include the slash between the two parts that gets thrown away)
       */
      start = name + len - TNMSZ - 1;
      while ((*start != '\0') && (*start != '/'))
            ++start;

      /*
       * if we hit the end of the string, this name cannot be split, so we
       * cannot store this file.
       */
      if (*start == '\0')
            return(NULL);
      len = start - name;

      /*
       * NOTE: /str where the length of str == TNMSZ can not be stored under
       * the p1003.1-1990 spec for ustar. We could force a prefix of / and
       * the file would then expand on extract to //str. The len == 0 below
       * makes this special case follow the spec to the letter.
       */
      if ((len > TPFSZ) || (len == 0))
            return(NULL);

      /*
       * ok have a split point, return it to the caller
       */
      return(start);
}

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