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[chaz/tar] / src / create.c

/* Create a tar archive.
   Copyright (C) 1985, 1992 Free Software Foundation

This file is part of GNU Tar.

GNU Tar is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Tar is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Tar; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
 * Create a tar archive.
 *
 * Written 25 Aug 1985 by John Gilmore, ihnp4!hoptoad!gnu.
 */

#ifdef _AIX
 #pragma alloca
#endif
#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
#ifndef STDC_HEADERS
extern int errno;
#endif

#ifdef BSD42
#include <sys/file.h>
#else
#ifndef V7
#include <fcntl.h>
#endif
#endif

#include "tar.h"
#include "port.h"

#ifndef __MSDOS__
#include <pwd.h>
#include <grp.h>
#endif

#if defined (_POSIX_VERSION)
#include <utime.h>
#else
struct utimbuf
{
  long actime;
  long modtime;
};

#endif

extern struct stat hstat;       /* Stat struct corresponding */

#ifndef __MSDOS__
extern dev_t ar_dev;
extern ino_t ar_ino;
#endif

/* JF */
extern struct name *gnu_list_name;

/*
 * If there are no symbolic links, there is no lstat().  Use stat().
 */
#ifndef S_ISLNK
#define lstat stat
#endif

extern void print_header ();

union record *start_header ();
void blank_name_list ();
int check_exclude ();
PTR ck_malloc ();
PTR ck_realloc ();
void clear_buffer ();
void close_archive ();
void collect_and_sort_names ();
int confirm ();
int deal_with_sparse ();
void find_new_file_size ();
void finish_header ();
int finish_sparse_file ();
void finduname ();
void findgname ();
int is_dot_or_dotdot ();
void open_archive ();
char *name_next ();
void name_close ();
void to_oct ();
void dump_file ();
void write_dir_file ();
void write_eot ();
void write_long ();
int zero_record ();

/* This code moved from tar.h since create.c is the only file that cares
   about 'struct link's.  This means that other files might not have to
   include sys/types.h any more. */

struct link
  {
    struct link *next;
    dev_t dev;
    ino_t ino;
    short linkcount;
    char name[1];
  };

struct link *linklist;          /* Points to first link in list */

static nolinks;                 /* Gets set if we run out of RAM */

/*
 * "Scratch" space to store the information about a sparse file before
 * writing the info into the header or extended header
 */
/* struct sp_array       *sparsearray;*/

/* number of elts storable in the sparsearray */
/*int   sparse_array_size = 10;*/

void
create_archive ()
{
  register char *p;
  char *name_from_list ();

  open_archive (0);             /* Open for writing */

  if (f_gnudump)
    {
      char *buf = ck_malloc (PATH_MAX);
      char *q, *bufp;

      collect_and_sort_names ();

      while (p = name_from_list ())
        dump_file (p, -1, 1);
      /* if(!f_dironly) { */
      blank_name_list ();
      while (p = name_from_list ())
        {
          strcpy (buf, p);
          if (p[strlen (p) - 1] != '/')
            strcat (buf, "/");
          bufp = buf + strlen (buf);
          for (q = gnu_list_name->dir_contents; q && *q; q += strlen (q) + 1)
            {
              if (*q == 'Y')
                {
                  strcpy (bufp, q + 1);
                  dump_file (buf, -1, 1);
                }
            }
        }
      /* } */
      free (buf);
    }
  else
    {
      p = name_next (1);
      do
        dump_file (p, -1, 1);
      while (p = name_next (1));
    }

  write_eot ();
  close_archive ();
  if (f_gnudump)
    write_dir_file ();
  name_close ();
}

/*
 * Dump a single file.  If it's a directory, recurse.
 * Result is 1 for success, 0 for failure.
 * Sets global "hstat" to stat() output for this file.
 */
void
dump_file (p, curdev, toplevel)
     char *p;                   /* File name to dump */
     int curdev;                /* Device our parent dir was on */
     int toplevel;              /* Whether we are a toplevel call */
{
  union record *header;
  char type;
  extern char *save_name;       /* JF for multi-volume support */
  extern long save_totsize;
  extern long save_sizeleft;
  union record *exhdr;
  char save_linkflag;
  extern time_t new_time;
  int critical_error = 0;
  struct utimbuf restore_times;
  /*    int sparse_ind = 0;*/


  if (f_confirm && !confirm ("add", p))
    return;

  /*
         * Use stat if following (rather than dumping) 4.2BSD's
         * symbolic links.  Otherwise, use lstat (which, on non-4.2
         * systems, is #define'd to stat anyway.
         */
#ifdef STX_HIDDEN               /* AIX */
  if (0 != f_follow_links ?
      statx (p, &hstat, STATSIZE, STX_HIDDEN) :
      statx (p, &hstat, STATSIZE, STX_HIDDEN | STX_LINK))
#else
  if (0 != f_follow_links ? stat (p, &hstat) : lstat (p, &hstat))
#endif
    {
    badperror:
      msg_perror ("can't add file %s", p);
    badfile:
      if (!f_ignore_failed_read || critical_error)
        errors++;
      return;
    }

  restore_times.actime = hstat.st_atime;
  restore_times.modtime = hstat.st_mtime;

#ifdef S_ISHIDDEN
  if (S_ISHIDDEN (hstat.st_mode))
    {
      char *new = (char *) alloca (strlen (p) + 2);
      if (new)
        {
          strcpy (new, p);
          strcat (new, "@");
          p = new;
        }
    }
#endif

  /* See if we only want new files, and check if this one is too old to
           put in the archive. */
  if (f_new_files
      && !f_gnudump
      && new_time > hstat.st_mtime
      && !S_ISDIR (hstat.st_mode)
      && (f_new_files > 1 || new_time > hstat.st_ctime))
    {
      if (curdev < 0)
        {
          msg ("%s: is unchanged; not dumped", p);
        }
      return;
    }

#ifndef __MSDOS__
  /* See if we are trying to dump the archive */
  if (ar_dev && hstat.st_dev == ar_dev && hstat.st_ino == ar_ino)
    {
      msg ("%s is the archive; not dumped", p);
      return;
    }
#endif
  /*
         * Check for multiple links.
         *
         * We maintain a list of all such files that we've written so
         * far.  Any time we see another, we check the list and
         * avoid dumping the data again if we've done it once already.
         */
  if (hstat.st_nlink > 1
      && (S_ISREG (hstat.st_mode)
#ifdef S_ISCTG
          || S_ISCTG (hstat.st_mode)
#endif
#ifdef S_ISCHR
          || S_ISCHR (hstat.st_mode)
#endif
#ifdef S_ISBLK
          || S_ISBLK (hstat.st_mode)
#endif
#ifdef S_ISFIFO
          || S_ISFIFO (hstat.st_mode)
#endif
      ))
    {
      register struct link *lp;

      /* First quick and dirty.  Hashing, etc later FIXME */
      for (lp = linklist; lp; lp = lp->next)
        {
          if (lp->ino == hstat.st_ino &&
              lp->dev == hstat.st_dev)
            {
              char *link_name = lp->name;

              /* We found a link. */
              while (!f_absolute_paths && *link_name == '/')
                {
                  static int link_warn = 0;

                  if (!link_warn)
                    {
                      msg ("Removing leading / from absolute links");
                      link_warn++;
                    }
                  link_name++;
                }
              if (link_name - lp->name >= NAMSIZ)
                write_long (link_name, LF_LONGLINK);
              current_link_name = link_name;

              hstat.st_size = 0;
              header = start_header (p, &hstat);
              if (header == NULL)
                {
                  critical_error = 1;
                  goto badfile;
                }
              strncpy (header->header.arch_linkname,
                       link_name, NAMSIZ);

              /* Force null truncated */
              header->header.arch_linkname[NAMSIZ - 1] = 0;

              header->header.linkflag = LF_LINK;
              finish_header (header);
              /* FIXME: Maybe remove from list after all links found? */
              if (f_remove_files)
                {
                  if (unlink (p) == -1)
                    msg_perror ("cannot remove %s", p);
                }
              return;           /* We dumped it */
            }
        }

      /* Not found.  Add it to the list of possible links. */
      lp = (struct link *) malloc ((unsigned) (sizeof (struct link) + strlen (p)));
      if (!lp)
        {
          if (!nolinks)
            {
              msg (
              "no memory for links, they will be dumped as separate files");
              nolinks++;
            }
        }
      lp->ino = hstat.st_ino;
      lp->dev = hstat.st_dev;
      strcpy (lp->name, p);
      lp->next = linklist;
      linklist = lp;
    }

  /*
         * This is not a link to a previously dumped file, so dump it.
         */
  if (S_ISREG (hstat.st_mode)
#ifdef S_ISCTG
      || S_ISCTG (hstat.st_mode)
#endif
    )
    {
      int f;                    /* File descriptor */
      long bufsize, count;
      long sizeleft;
      register union record *start;
      int header_moved;
      char isextended = 0;
      int upperbound;
      /*                int     end_nulls = 0; */

      header_moved = 0;

#ifdef BSD42
      if (f_sparse_files)
        {
          /*
                 * JK - This is the test for sparseness: whether the
                 * "size" of the file matches the number of blocks
                 * allocated for it.  If there is a smaller number
                 * of blocks that would be necessary to accommodate
                 * a file of this size, we have a sparse file, i.e.,
                 * at least one of those records in the file is just
                 * a useless hole.
                 */
#ifdef hpux                     /* Nice of HPUX to gratuitiously change it, huh?  - mib */
          if (hstat.st_size - (hstat.st_blocks * 1024) > 1024)
#else
          if (hstat.st_size - (hstat.st_blocks * RECORDSIZE) > RECORDSIZE)
#endif
            {
              int filesize = hstat.st_size;
              register int i;

              header = start_header (p, &hstat);
              if (header == NULL)
                {
                  critical_error = 1;
                  goto badfile;
                }
              header->header.linkflag = LF_SPARSE;
              header_moved++;

              /*
                         * Call the routine that figures out the
                         * layout of the sparse file in question.
                         * UPPERBOUND is the index of the last
                         * element of the "sparsearray," i.e.,
                         * the number of elements it needed to
                         * describe the file.
                         */

              upperbound = deal_with_sparse (p, header);

              /*
                         * See if we'll need an extended header
                         * later
                         */
              if (upperbound > SPARSE_IN_HDR - 1)
                header->header.isextended++;
              /*
                         * We store the "real" file size so
                         * we can show that in case someone wants
                         * to list the archive, i.e., tar tvf <file>.
                         * It might be kind of disconcerting if the
                         * shrunken file size was the one that showed
                         * up.
                         */
              to_oct ((long) hstat.st_size, 1 + 12,
                      header->header.realsize);

              /*
                         * This will be the new "size" of the
                         * file, i.e., the size of the file
                         * minus the records of holes that we're
                         * skipping over.
                         */

              find_new_file_size (&filesize, upperbound);
              hstat.st_size = filesize;
              to_oct ((long) filesize, 1 + 12,
                      header->header.size);
              /*                                to_oct((long) end_nulls, 1+12,
                                                header->header.ending_blanks);*/

              for (i = 0; i < SPARSE_IN_HDR; i++)
                {
                  if (!sparsearray[i].numbytes)
                    break;
                  to_oct (sparsearray[i].offset, 1 + 12,
                          header->header.sp[i].offset);
                  to_oct (sparsearray[i].numbytes, 1 + 12,
                          header->header.sp[i].numbytes);
                }

            }
        }
#else
      upperbound = SPARSE_IN_HDR - 1;
#endif

      sizeleft = hstat.st_size;
      /* Don't bother opening empty, world readable files. */
      if (sizeleft > 0 || 0444 != (0444 & hstat.st_mode))
        {
          f = open (p, O_RDONLY | O_BINARY);
          if (f < 0)
            goto badperror;
        }
      else
        {
          f = -1;
        }

      /* If the file is sparse, we've already taken care of this */
      if (!header_moved)
        {
          header = start_header (p, &hstat);
          if (header == NULL)
            {
              if (f >= 0)
                (void) close (f);
              critical_error = 1;
              goto badfile;
            }
        }
#ifdef S_ISCTG
      /* Mark contiguous files, if we support them */
      if (f_standard && S_ISCTG (hstat.st_mode))
        {
          header->header.linkflag = LF_CONTIG;
        }
#endif
      isextended = header->header.isextended;
      save_linkflag = header->header.linkflag;
      finish_header (header);
      if (isextended)
        {
          /*                    int      sum = 0;*/
          register int i;
          /*                    register union record *exhdr;*/
          /*                    int      arraybound = SPARSE_EXT_HDR;*/
          /* static */ int index_offset = SPARSE_IN_HDR;

        extend:exhdr = findrec ();

          if (exhdr == NULL)
            {
              critical_error = 1;
              goto badfile;
            }
          bzero (exhdr->charptr, RECORDSIZE);
          for (i = 0; i < SPARSE_EXT_HDR; i++)
            {
              if (i + index_offset > upperbound)
                break;
              to_oct ((long) sparsearray[i + index_offset].numbytes,
                      1 + 12,
                      exhdr->ext_hdr.sp[i].numbytes);
              to_oct ((long) sparsearray[i + index_offset].offset,
                      1 + 12,
                      exhdr->ext_hdr.sp[i].offset);
            }
          userec (exhdr);
          /*                    sum += i;
                        if (sum < upperbound)
                                goto extend;*/
          if (index_offset + i < upperbound)
            {
              index_offset += i;
              exhdr->ext_hdr.isextended++;
              goto extend;
            }

        }
      if (save_linkflag == LF_SPARSE)
        {
          if (finish_sparse_file (f, &sizeleft, hstat.st_size, p))
            goto padit;
        }
      else
        while (sizeleft > 0)
          {

            if (f_multivol)
              {
                save_name = p;
                save_sizeleft = sizeleft;
                save_totsize = hstat.st_size;
              }
            start = findrec ();

            bufsize = endofrecs ()->charptr - start->charptr;

            if (sizeleft < bufsize)
              {
                /* Last read -- zero out area beyond */
                bufsize = (int) sizeleft;
                count = bufsize % RECORDSIZE;
                if (count)
                  bzero (start->charptr + sizeleft,
                         (int) (RECORDSIZE - count));
              }
            count = read (f, start->charptr, bufsize);
            if (count < 0)
              {
                msg_perror ("read error at byte %ld, reading\
 %d bytes, in file %s", hstat.st_size - sizeleft, bufsize, p);
                goto padit;
              }
            sizeleft -= count;

            /* This is nonportable (the type of userec's arg). */
            userec (start + (count - 1) / RECORDSIZE);

            if (count == bufsize)
              continue;
            msg ("file %s shrunk by %d bytes, padding with zeros.", p, sizeleft);
            goto padit;         /* Short read */
          }

      if (f_multivol)
        save_name = 0;

      if (f >= 0)
        (void) close (f);

      if (f_remove_files)
        {
          if (unlink (p) == -1)
            msg_perror ("cannot remove %s", p);
        }
      if (f_atime_preserve)
        utime (p, &restore_times);
      return;

      /*
                 * File shrunk or gave error, pad out tape to match
                 * the size we specified in the header.
                 */
    padit:
      while (sizeleft > 0)
        {
          save_sizeleft = sizeleft;
          start = findrec ();
          bzero (start->charptr, RECORDSIZE);
          userec (start);
          sizeleft -= RECORDSIZE;
        }
      if (f_multivol)
        save_name = 0;
      if (f >= 0)
        (void) close (f);
      if (f_atime_preserve)
        utime (p, &restore_times);
      return;
    }

#ifdef S_ISLNK
  else if (S_ISLNK (hstat.st_mode))
    {
      int size;
      char *buf = alloca (PATH_MAX + 1);

      size = readlink (p, buf, PATH_MAX + 1);
      if (size < 0)
        goto badperror;
      buf[size] = '\0';
      if (size >= NAMSIZ)
        write_long (buf, LF_LONGLINK);
      current_link_name = buf;

      hstat.st_size = 0;        /* Force 0 size on symlink */
      header = start_header (p, &hstat);
      if (header == NULL)
        {
          critical_error = 1;
          goto badfile;
        }
      strncpy (header->header.arch_linkname, buf, NAMSIZ);
      header->header.arch_linkname[NAMSIZ - 1] = '\0';
      header->header.linkflag = LF_SYMLINK;
      finish_header (header);   /* Nothing more to do to it */
      if (f_remove_files)
        {
          if (unlink (p) == -1)
            msg_perror ("cannot remove %s", p);
        }
      return;
    }
#endif

  else if (S_ISDIR (hstat.st_mode))
    {
      register DIR *dirp;
      register struct dirent *d;
      char *namebuf;
      int buflen;
      register int len;
      int our_device = hstat.st_dev;

      /* Build new prototype name */
      len = strlen (p);
      buflen = len + NAMSIZ;
      namebuf = ck_malloc (buflen + 1);
      strncpy (namebuf, p, buflen);
      while (len >= 1 && '/' == namebuf[len - 1])
        len--;                  /* Delete trailing slashes */
      namebuf[len++] = '/';     /* Now add exactly one back */
      namebuf[len] = '\0';      /* Make sure null-terminated */

      /*
                 * Output directory header record with permissions
                 * FIXME, do this AFTER files, to avoid R/O dir problems?
                 * If old archive format, don't write record at all.
                 */
      if (!f_oldarch)
        {
          hstat.st_size = 0;    /* Force 0 size on dir */
          /*
                         * If people could really read standard archives,
                         * this should be:              (FIXME)
                        header = start_header(f_standard? p: namebuf, &hstat);
                         * but since they'd interpret LF_DIR records as
                         * regular files, we'd better put the / on the name.
                         */
          header = start_header (namebuf, &hstat);
          if (header == NULL)
            {
              critical_error = 1;
              goto badfile;     /* eg name too long */
            }

          if (f_gnudump)
            header->header.linkflag = LF_DUMPDIR;
          else if (f_standard)
            header->header.linkflag = LF_DIR;

          /* If we're gnudumping, we aren't done yet so don't close it. */
          if (!f_gnudump)
            finish_header (header);     /* Done with directory header */
        }

      if (f_gnudump)
        {
          int sizeleft;
          int totsize;
          int bufsize;
          union record *start;
          int count;
          char *buf, *p_buf;

          buf = gnu_list_name->dir_contents;    /* FOO */
          totsize = 0;
          for (p_buf = buf; p_buf && *p_buf;)
            {
              int tmp;

              tmp = strlen (p_buf) + 1;
              totsize += tmp;
              p_buf += tmp;
            }
          totsize++;
          to_oct ((long) totsize, 1 + 12, header->header.size);
          finish_header (header);
          p_buf = buf;
          sizeleft = totsize;
          while (sizeleft > 0)
            {
              if (f_multivol)
                {
                  save_name = p;
                  save_sizeleft = sizeleft;
                  save_totsize = totsize;
                }
              start = findrec ();
              bufsize = endofrecs ()->charptr - start->charptr;
              if (sizeleft < bufsize)
                {
                  bufsize = sizeleft;
                  count = bufsize % RECORDSIZE;
                  if (count)
                    bzero (start->charptr + sizeleft, RECORDSIZE - count);
                }
              bcopy (p_buf, start->charptr, bufsize);
              sizeleft -= bufsize;
              p_buf += bufsize;
              userec (start + (bufsize - 1) / RECORDSIZE);
            }
          if (f_multivol)
            save_name = 0;
          if (f_atime_preserve)
            utime (p, &restore_times);
          return;
        }

      /* Now output all the files in the directory */
#if 0
      if (f_dironly)
        return;                 /* Unless the cmdline said not to */
#endif
      /*
                 * See if we are crossing from one file system to another,
                 * and avoid doing so if the user only wants to dump one file system.
                 */
      if (f_local_filesys && !toplevel && curdev != hstat.st_dev)
        {
          if (f_verbose)
            msg ("%s: is on a different filesystem; not dumped", p);
          return;
        }


      errno = 0;
      dirp = opendir (p);
      if (!dirp)
        {
          if (errno)
            {
              msg_perror ("can't open directory %s", p);
            }
          else
            {
              msg ("error opening directory %s",
                   p);
            }
          return;
        }

      /* Hack to remove "./" from the front of all the file names */
      if (len == 2 && namebuf[0] == '.' && namebuf[1] == '/')
        len = 0;

      /* Should speed this up by cd-ing into the dir, FIXME */
      while (NULL != (d = readdir (dirp)))
        {
          /* Skip . and .. */
          if (is_dot_or_dotdot (d->d_name))
            continue;

          if (NLENGTH (d) + len >= buflen)
            {
              buflen = len + NLENGTH (d);
              namebuf = ck_realloc (namebuf, buflen + 1);
              /* namebuf[len]='\0';
                                msg("file name %s%s too long",
                                        namebuf, d->d_name);
                                continue; */
            }
          strcpy (namebuf + len, d->d_name);
          if (f_exclude && check_exclude (namebuf))
            continue;
          dump_file (namebuf, our_device, 0);
        }

      closedir (dirp);
      free (namebuf);
      if (f_atime_preserve)
        utime (p, &restore_times);
      return;
    }

#ifdef S_ISCHR
  else if (S_ISCHR (hstat.st_mode))
    {
      type = LF_CHR;
    }
#endif

#ifdef S_ISBLK
  else if (S_ISBLK (hstat.st_mode))
    {
      type = LF_BLK;
    }
#endif

  /* Avoid screwy apollo lossage where S_IFIFO == S_IFSOCK */
#if (_ISP__M68K == 0) && (_ISP__A88K == 0) && defined(S_ISFIFO)
  else if (S_ISFIFO (hstat.st_mode))
    {
      type = LF_FIFO;
    }
#endif

#ifdef S_ISSOCK
  else if (S_ISSOCK (hstat.st_mode))
    {
      type = LF_FIFO;
    }
#endif
  else
    goto unknown;

  if (!f_standard)
    goto unknown;

  hstat.st_size = 0;            /* Force 0 size */
  header = start_header (p, &hstat);
  if (header == NULL)
    {
      critical_error = 1;
      goto badfile;             /* eg name too long */
    }

  header->header.linkflag = type;
#if defined(S_IFBLK) || defined(S_IFCHR)
  if (type != LF_FIFO)
    {
      to_oct ((long) major (hstat.st_rdev), 8,
              header->header.devmajor);
      to_oct ((long) minor (hstat.st_rdev), 8,
              header->header.devminor);
    }
#endif

  finish_header (header);
  if (f_remove_files)
    {
      if (unlink (p) == -1)
        msg_perror ("cannot remove %s", p);
    }
  return;

unknown:
  msg ("%s: Unknown file type; file ignored.", p);
}

int
finish_sparse_file (fd, sizeleft, fullsize, name)
     int fd;
     long *sizeleft, fullsize;
     char *name;
{
  union record *start;
  char tempbuf[RECORDSIZE];
  int bufsize, sparse_ind = 0, count;
  long pos;
  long nwritten = 0;


  while (*sizeleft > 0)
    {
      start = findrec ();
      bzero (start->charptr, RECORDSIZE);
      bufsize = sparsearray[sparse_ind].numbytes;
      if (!bufsize)
        {                       /* we blew it, maybe */
          msg ("Wrote %ld of %ld bytes to file %s",
               fullsize - *sizeleft, fullsize, name);
          break;
        }
      pos = lseek (fd, sparsearray[sparse_ind++].offset, 0);
      /*
                 * If the number of bytes to be written here exceeds
                 * the size of the temporary buffer, do it in steps.
                 */
      while (bufsize > RECORDSIZE)
        {
          /*                    if (amt_read) {
                                count = read(fd, start->charptr+amt_read, RECORDSIZE-amt_read);
                                bufsize -= RECORDSIZE - amt_read;
                                amt_read = 0;
                                userec(start);
                                start = findrec();
                                bzero(start->charptr, RECORDSIZE);
                        }*/
          /* store the data */
          count = read (fd, start->charptr, RECORDSIZE);
          if (count < 0)
            {
              msg_perror ("read error at byte %ld, reading %d bytes, in file %s",
                          fullsize - *sizeleft, bufsize, name);
              return 1;
            }
          bufsize -= count;
          *sizeleft -= count;
          userec (start);
          nwritten += RECORDSIZE;       /* XXX */
          start = findrec ();
          bzero (start->charptr, RECORDSIZE);
        }


      clear_buffer (tempbuf);
      count = read (fd, tempbuf, bufsize);
      bcopy (tempbuf, start->charptr, RECORDSIZE);
      if (count < 0)
        {
          msg_perror ("read error at byte %ld, reading %d bytes, in file %s",
                      fullsize - *sizeleft, bufsize, name);
          return 1;
        }
      /*                if (amt_read >= RECORDSIZE) {
                        amt_read = 0;
                        userec(start+(count-1)/RECORDSIZE);
                        if (count != bufsize) {
                                msg("file %s shrunk by %d bytes, padding with zeros.", name, sizeleft);
                                return 1;
                        }
                        start = findrec();
                } else
                        amt_read += bufsize;*/
      nwritten += count;        /* XXX */
      *sizeleft -= count;
      userec (start);

    }
  free (sparsearray);
  /*    printf ("Amount actually written is (I hope) %d.\n", nwritten); */
  /*    userec(start+(count-1)/RECORDSIZE);*/
  return 0;

}

void
init_sparsearray ()
{
  register int i;

  sp_array_size = 10;
  /*
         * Make room for our scratch space -- initially is 10 elts long
         */
  sparsearray = (struct sp_array *) malloc (sp_array_size * sizeof (struct sp_array));
  for (i = 0; i < sp_array_size; i++)
    {
      sparsearray[i].offset = 0;
      sparsearray[i].numbytes = 0;
    }
}



/*
 * Okay, we've got a sparse file on our hands -- now, what we need to do is
 * make a pass through the file and carefully note where any data is, i.e.,
 * we want to find how far into the file each instance of data is, and how
 * many bytes are there.  We store this information in the sparsearray,
 * which will later be translated into header information.  For now, we use
 * the sparsearray as convenient storage.
 *
 * As a side note, this routine is a mess.  If I could have found a cleaner
 * way to do it, I would have.  If anyone wants to find a nicer way to do
 * this, feel free.
 */

/* There is little point in trimming small amounts of null data at the */
/* head and tail of blocks -- it's ok if we only avoid dumping blocks */
/* of complete null data */
int
deal_with_sparse (name, header, nulls_at_end)
     char *name;
     union record *header;
     int nulls_at_end;
{
  long numbytes = 0;
  long offset = 0;
  /*    long    save_offset;*/
  int fd;
  /*    int     current_size = hstat.st_size;*/
  int sparse_ind = 0, cc;
  char buf[RECORDSIZE];
#if 0
  int read_last_data = 0;       /* did we just read the last record? */
#endif
  int amidst_data = 0;

  header->header.isextended = 0;
  /*
         * Can't open the file -- this problem will be caught later on,
         * so just return.
         */
  if ((fd = open (name, O_RDONLY)) < 0)
    return 0;

  init_sparsearray ();
  clear_buffer (buf);

  while ((cc = read (fd, buf, sizeof buf)) != 0)
    {

      if (sparse_ind > sp_array_size - 1)
        {

          /*
                 * realloc the scratch area, since we've run out of room --
                 */
          sparsearray = (struct sp_array *)
            realloc (sparsearray,
                     2 * sp_array_size * (sizeof (struct sp_array)));
          sp_array_size *= 2;
        }
      if (cc == sizeof buf)
        {
          if (zero_record (buf))
            {
              if (amidst_data)
                {
                  sparsearray[sparse_ind++].numbytes
                    = numbytes;
                  amidst_data = 0;
                }
            }
          else
            {                   /* !zero_record(buf) */
              if (amidst_data)
                numbytes += cc;
              else
                {
                  amidst_data = 1;
                  numbytes = cc;
                  sparsearray[sparse_ind].offset
                    = offset;
                }
            }
        }
      else if (cc < sizeof buf)
        {
          /* This has to be the last bit of the file, so this */
          /* is somewhat shorter than the above. */
          if (!zero_record (buf))
            {
              if (!amidst_data)
                {
                  amidst_data = 1;
                  numbytes = cc;
                  sparsearray[sparse_ind].offset
                    = offset;
                }
              else
                numbytes += cc;
            }
        }
      offset += cc;
      clear_buffer (buf);
    }
  if (amidst_data)
    sparsearray[sparse_ind++].numbytes = numbytes;
  close (fd);

  return sparse_ind - 1;
}

/*
 * Just zeroes out the buffer so we don't confuse ourselves with leftover
 * data.
 */
void
clear_buffer (buf)
     char *buf;
{
  register int i;

  for (i = 0; i < RECORDSIZE; i++)
    buf[i] = '\0';
}

#if 0                           /* I'm leaving this as a monument to Joy Kendall, who wrote it -mib */
/*
 * JK -
 * This routine takes a character array, and tells where within that array
 * the data can be found.  It skips over any zeros, and sets the first
 * non-zero point in the array to be the "start", and continues until it
 * finds non-data again, which is marked as the "end."  This routine is
 * mainly for 1) seeing how far into a file we must lseek to data, given
 * that we have a sparse file, and 2) determining the "real size" of the
 * file, i.e., the number of bytes in the sparse file that are data, as
 * opposed to the zeros we are trying to skip.
 */
where_is_data (from, to, buffer)
     int *from, *to;
     char *buffer;
{
  register int i = 0;
  register int save_to = *to;
  int amidst_data = 0;


  while (!buffer[i])
    i++;
  *from = i;

  if (*from < 16)               /* don't bother */
    *from = 0;
  /* keep going to make sure there isn't more real
           data in this record */
  while (i < RECORDSIZE)
    {
      if (!buffer[i])
        {
          if (amidst_data)
            {
              save_to = i;
              amidst_data = 0;
            }
          i++;
        }
      else if (buffer[i])
        {
          if (!amidst_data)
            amidst_data = 1;
          i++;
        }
    }
  if (i == RECORDSIZE)
    *to = i;
  else
    *to = save_to;

}

#endif

/* Note that this routine is only called if zero_record returned true */
#if 0                           /* But we actually don't need it at all. */
where_is_data (from, to, buffer)
     int *from, *to;
     char *buffer;
{
  char *fp, *tp;

  for (fp = buffer; !*fp; fp++)
    ;
  for (tp = buffer + RECORDSIZE - 1; !*tp; tp--)
    ;
  *from = fp - buffer;
  *to = tp - buffer + 1;
}

#endif



/*
 * Takes a recordful of data and basically cruises through it to see if
 * it's made *entirely* of zeros, returning a 0 the instant it finds
 * something that is a non-zero, i.e., useful data.
 */
int
zero_record (buffer)
     char *buffer;
{
  register int i;

  for (i = 0; i < RECORDSIZE; i++)
    if (buffer[i] != '\000')
      return 0;
  return 1;
}

void
find_new_file_size (filesize, highest_index)
     int *filesize;
     int highest_index;
{
  register int i;

  *filesize = 0;
  for (i = 0; sparsearray[i].numbytes && i <= highest_index; i++)
    *filesize += sparsearray[i].numbytes;
}

/*
 * Make a header block for the file  name  whose stat info is  st .
 * Return header pointer for success, NULL if the name is too long.
 */
union record *
start_header (name, st)
     char *name;
     register struct stat *st;
{
  register union record *header;

  if (strlen (name) >= NAMSIZ)
    write_long (name, LF_LONGNAME);

  header = (union record *) findrec ();
  bzero (header->charptr, sizeof (*header));    /* XXX speed up */

  /*
         * Check the file name and put it in the record.
         */
  if (!f_absolute_paths)
    {
      static int warned_once = 0;
#ifdef __MSDOS__
      if (name[1] == ':')
        {
          name += 2;
          if (!warned_once++)
            msg ("Removing drive spec from names in the archive");
        }
#endif
      while ('/' == *name)
        {
          name++;               /* Force relative path */
          if (!warned_once++)
            msg ("Removing leading / from absolute path names in the archive.");
        }
    }
  current_file_name = name;
  strncpy (header->header.arch_name, name, NAMSIZ);
  header->header.arch_name[NAMSIZ - 1] = '\0';

  to_oct ((long) (st->st_mode & 07777),
          8, header->header.mode);
  to_oct ((long) st->st_uid, 8, header->header.uid);
  to_oct ((long) st->st_gid, 8, header->header.gid);
  to_oct ((long) st->st_size, 1 + 12, header->header.size);
  to_oct ((long) st->st_mtime, 1 + 12, header->header.mtime);
  /* header->header.linkflag is left as null */
  if (f_gnudump)
    {
      to_oct ((long) st->st_atime, 1 + 12, header->header.atime);
      to_oct ((long) st->st_ctime, 1 + 12, header->header.ctime);
    }

#ifndef NONAMES
  /* Fill in new Unix Standard fields if desired. */
  if (f_standard)
    {
      header->header.linkflag = LF_NORMAL;      /* New default */
      strcpy (header->header.magic, TMAGIC);    /* Mark as Unix Std */
      finduname (header->header.uname, st->st_uid);
      findgname (header->header.gname, st->st_gid);
    }
#endif
  return header;
}

/*
 * Finish off a filled-in header block and write it out.
 * We also print the file name and/or full info if verbose is on.
 */
void
finish_header (header)
     register union record *header;
{
  register int i, sum;
  register char *p;

  bcopy (CHKBLANKS, header->header.chksum, sizeof (header->header.chksum));

  sum = 0;
  p = header->charptr;
  for (i = sizeof (*header); --i >= 0;)
    {
      /*
                 * We can't use unsigned char here because of old compilers,
                 * e.g. V7.
                 */
      sum += 0xFF & *p++;
    }

  /*
         * Fill in the checksum field.  It's formatted differently
         * from the other fields:  it has [6] digits, a null, then a
         * space -- rather than digits, a space, then a null.
         * We use to_oct then write the null in over to_oct's space.
         * The final space is already there, from checksumming, and
         * to_oct doesn't modify it.
         *
         * This is a fast way to do:
         * (void) sprintf(header->header.chksum, "%6o", sum);
         */
  to_oct ((long) sum, 8, header->header.chksum);
  header->header.chksum[6] = '\0';      /* Zap the space */

  userec (header);

  if (f_verbose)
    {
      extern union record *head;/* Points to current tape header */
      extern int head_standard; /* Tape header is in ANSI format */

      /* These globals are parameters to print_header, sigh */
      head = header;
      /* hstat is already set up */
      head_standard = f_standard;
      print_header ();
    }

  return;
}


/*
 * Quick and dirty octal conversion.
 * Converts long "value" into a "digs"-digit field at "where",
 * including a trailing space and room for a null.  "digs"==3 means
 * 1 digit, a space, and room for a null.
 *
 * We assume the trailing null is already there and don't fill it in.
 * This fact is used by start_header and finish_header, so don't change it!
 *
 * This should be equivalent to:
 *      (void) sprintf(where, "%*lo ", digs-2, value);
 * except that sprintf fills in the trailing null and we don't.
 */
void
to_oct (value, digs, where)
     register long value;
     register int digs;
     register char *where;
{

  --digs;                       /* Trailing null slot is left alone */
  where[--digs] = ' ';          /* Put in the space, though */

  /* Produce the digits -- at least one */
  do
    {
      where[--digs] = '0' + (char) (value & 7); /* one octal digit */
      value >>= 3;
    }
  while (digs > 0 && value != 0);

  /* Leading spaces, if necessary */
  while (digs > 0)
    where[--digs] = ' ';

}


/*
 * Write the EOT record(s).
 * We actually zero at least one record, through the end of the block.
 * Old tar writes garbage after two zeroed records -- and PDtar used to.
 */
void
write_eot ()
{
  union record *p;
  int bufsize;

  p = findrec ();
  if (p)
    {
      bufsize = endofrecs ()->charptr - p->charptr;
      bzero (p->charptr, bufsize);
      userec (p);
    }
}

/* Write a LF_LONGLINK or LF_LONGNAME record. */
void
write_long (p, type)
     char *p;
     char type;
{
  int size = strlen (p) + 1;
  int bufsize;
  union record *header;
  struct stat foo;


  bzero (&foo, sizeof foo);
  foo.st_size = size;

  header = start_header ("././@LongLink", &foo);
  header->header.linkflag = type;
  finish_header (header);

  header = findrec ();

  bufsize = endofrecs ()->charptr - header->charptr;

  while (bufsize < size)
    {
      bcopy (p, header->charptr, bufsize);
      p += bufsize;
      size -= bufsize;
      userec (header + (bufsize - 1) / RECORDSIZE);
      header = findrec ();
      bufsize = endofrecs ()->charptr - header->charptr;
    }
  bcopy (p, header->charptr, size);
  bzero (header->charptr + size, bufsize - size);
  userec (header + (size - 1) / RECORDSIZE);
}