create.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

      {
	TIME_TO_CHARS (st->atime.tv_sec, header->oldgnu_header.atime);
	TIME_TO_CHARS (st->ctime.tv_sec, header->oldgnu_header.ctime);
      }

  header->header.typeflag = archive_format == V7_FORMAT ? AREGTYPE : REGTYPE;

  switch (archive_format)
    {
    case V7_FORMAT:
      break;

    case OLDGNU_FORMAT:
    case GNU_FORMAT:   /*FIXME?*/
      /* Overwrite header->header.magic and header.version in one blow.  */
      strcpy (header->header.magic, OLDGNU_MAGIC);
      break;

    case POSIX_FORMAT:
    case USTAR_FORMAT:
      strncpy (header->header.magic, TMAGIC, TMAGLEN);
      strncpy (header->header.version, TVERSION, TVERSLEN);
      break;

    default:
      abort ();
    }

  if (archive_format == V7_FORMAT || numeric_owner_option)
    {
      /* header->header.[ug]name are left as the empty string.  */
    }
  else
    {
      uid_to_uname (st->stat.st_uid, &st->uname);
      gid_to_gname (st->stat.st_gid, &st->gname);

      if (archive_format == POSIX_FORMAT
	  && (strlen (st->uname) > UNAME_FIELD_SIZE
	      || !string_ascii_p (st->uname)))
	xheader_store ("uname", st, NULL);
      UNAME_TO_CHARS (st->uname, header->header.uname);

      if (archive_format == POSIX_FORMAT
	  && (strlen (st->gname) > GNAME_FIELD_SIZE
	      || !string_ascii_p (st->gname)))
	xheader_store ("gname", st, NULL);
      GNAME_TO_CHARS (st->gname, header->header.gname);
    }

  return header;
}

void
simple_finish_header (union block *header)
{
  size_t i;
  int sum;
  char *p;

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

  sum = 0;
  p = header->buffer;
  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, then a null.  We use to_chars.
     The final space is already there, from
     checksumming, and to_chars doesn't modify it.

     This is a fast way to do:

     sprintf(header->header.chksum, "%6o", sum);  */

  uintmax_to_chars ((uintmax_t) sum, header->header.chksum, 7);

  set_next_block_after (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.  If BLOCK_ORDINAL
   is not negative, is the block ordinal of the first record for this
   file, which may be a preceding long name or long link record.  */
void
finish_header (struct tar_stat_info *st,
	       union block *header, off_t block_ordinal)
{
  /* Note: It is important to do this before the call to write_extended(),
     so that the actual ustar header is printed */
  if (verbose_option
      && header->header.typeflag != GNUTYPE_LONGLINK
      && header->header.typeflag != GNUTYPE_LONGNAME
      && header->header.typeflag != XHDTYPE
      && header->header.typeflag != XGLTYPE)
    {
      /* These globals are parameters to print_header, sigh.  */

      current_header = header;
      current_format = archive_format;
      print_header (st, block_ordinal);
    }

  header = write_extended (false, st, header);
  simple_finish_header (header);
}


void
pad_archive (off_t size_left)
{
  union block *blk;
  while (size_left > 0)
    {
      mv_size_left (size_left);
      blk = find_next_block ();
      memset (blk->buffer, 0, BLOCKSIZE);
      set_next_block_after (blk);
      size_left -= BLOCKSIZE;
    }
}

static enum dump_status
dump_regular_file (int fd, struct tar_stat_info *st)
{
  off_t size_left = st->stat.st_size;
  off_t block_ordinal;
  union block *blk;

  block_ordinal = current_block_ordinal ();
  blk = start_header (st);
  if (!blk)
    return dump_status_fail;

  /* Mark contiguous files, if we support them.  */
  if (archive_format != V7_FORMAT && S_ISCTG (st->stat.st_mode))
    blk->header.typeflag = CONTTYPE;

  finish_header (st, blk, block_ordinal);

  mv_begin (st);
  while (size_left > 0)
    {
      size_t bufsize, count;

      mv_size_left (size_left);

      blk = find_next_block ();

      bufsize = available_space_after (blk);

      if (size_left < bufsize)
	{
	  /* Last read -- zero out area beyond.  */
	  bufsize = size_left;
	  count = bufsize % BLOCKSIZE;
	  if (count)
	    memset (blk->buffer + size_left, 0, BLOCKSIZE - count);
	}

      count = (fd < 0) ? bufsize : safe_read (fd, blk->buffer, bufsize);
      if (count == SAFE_READ_ERROR)
	{
	  read_diag_details (st->orig_file_name,
	                     st->stat.st_size - size_left, bufsize);
	  pad_archive (size_left);
	  return dump_status_short;
	}
      size_left -= count;
      set_next_block_after (blk + (bufsize - 1) / BLOCKSIZE);

      if (count != bufsize)
	{
	  char buf[UINTMAX_STRSIZE_BOUND];
	  memset (blk->buffer + count, 0, bufsize - count);
	  WARN ((0, 0,
		 ngettext ("%s: File shrank by %s byte; padding with zeros",
			   "%s: File shrank by %s bytes; padding with zeros",
			   size_left),
		 quotearg_colon (st->orig_file_name),
		 STRINGIFY_BIGINT (size_left, buf)));
	  if (! ignore_failed_read_option) 
	    exit_status = TAREXIT_DIFFERS;
	  pad_archive (size_left - (bufsize - count));
	  return dump_status_short;
	}
    }
  return dump_status_ok;
}


static void
dump_dir0 (char *directory,
	   struct tar_stat_info *st, int top_level, dev_t parent_device)
{
  dev_t our_device = st->stat.st_dev;
  const char *tag_file_name;
  
  if (!is_avoided_name (st->orig_file_name))
    {
      union block *blk = NULL;
      off_t block_ordinal = current_block_ordinal ();
      st->stat.st_size = 0;	/* force 0 size on dir */

      blk = start_header (st);
      if (!blk)
	return;

      if (incremental_option && archive_format != POSIX_FORMAT)
	blk->header.typeflag = GNUTYPE_DUMPDIR;
      else /* if (standard_option) */
	blk->header.typeflag = DIRTYPE;

      /* If we're gnudumping, we aren't done yet so don't close it.  */

      if (!incremental_option)
	finish_header (st, blk, block_ordinal);
      else if (gnu_list_name->dir_contents)
	{
	  if (archive_format == POSIX_FORMAT)
	    {
	      xheader_store ("GNU.dumpdir", st, gnu_list_name->dir_contents);
	      finish_header (st, blk, block_ordinal);
	    }
	  else
	    {
	      off_t size_left;
	      off_t totsize;
	      size_t bufsize;
	      ssize_t count;
	      const char *buffer, *p_buffer;

	      block_ordinal = current_block_ordinal ();
	      buffer = gnu_list_name->dir_contents;
	      if (buffer)
		totsize = dumpdir_size (buffer);
	      else
		totsize = 0;
	      OFF_TO_CHARS (totsize, blk->header.size);
	      finish_header (st, blk, block_ordinal);
	      p_buffer = buffer;
	      size_left = totsize;

	      mv_begin (st);
	      mv_total_size (totsize);
	      while (size_left > 0)
		{
		  mv_size_left (size_left);
		  blk = find_next_block ();
		  bufsize = available_space_after (blk);
		  if (size_left < bufsize)
		    {
		      bufsize = size_left;
		      count = bufsize % BLOCKSIZE;
		      if (count)
			memset (blk->buffer + size_left, 0, BLOCKSIZE - count);
		    }
		  memcpy (blk->buffer, p_buffer, bufsize);
		  size_left -= bufsize;
		  p_buffer += bufsize;
		  set_next_block_after (blk + (bufsize - 1) / BLOCKSIZE);
		}
	      mv_end ();
	    }
	  return;
	}
    }

  if (!recursion_option)
    return;

  if (one_file_system_option
      && !top_level
      && parent_device != st->stat.st_dev)
    {
      if (verbose_option)
	WARN ((0, 0,
	       _("%s: file is on a different filesystem; not dumped"),
	       quotearg_colon (st->orig_file_name)));
    }
  else
    {
      char *name_buf;
      size_t name_size;
      
      switch (check_exclusion_tags (st->orig_file_name, &tag_file_name))
	{
	case exclusion_tag_all:
	  /* Handled in dump_file0 */
	  break;
	  
	case exclusion_tag_none:
	  {
	    char const *entry;
	    size_t entry_len;
	    size_t name_len;

	    name_buf = xstrdup (st->orig_file_name);
	    name_size = name_len = strlen (name_buf);

	    /* Now output all the files in the directory.  */
	    /* FIXME: Should speed this up by cd-ing into the dir.  */
	    for (entry = directory; (entry_len = strlen (entry)) != 0;
		 entry += entry_len + 1)
	      {
		if (name_size < name_len + entry_len)
		  {
		    name_size = name_len + entry_len;
		    name_buf = xrealloc (name_buf, name_size + 1);
		  }
		strcpy (name_buf + name_len, entry);
		if (!excluded_name (name_buf))
		  dump_file (name_buf, 0, our_device);
	      }
	    
	    free (name_buf);
	  }
	  break;

	case exclusion_tag_contents:
	  exclusion_tag_warning (st->orig_file_name, tag_file_name,
				 _("contents not dumped"));
	  name_size = strlen (st->orig_file_name) + strlen (tag_file_name) + 1;
	  name_buf = xmalloc (name_size);
	  strcpy (name_buf, st->orig_file_name);
	  strcat (name_buf, tag_file_name);
	  dump_file (name_buf, 0, our_device);
	  free (name_buf);
	  break;
      
	case exclusion_tag_under:
	  exclusion_tag_warning (st->orig_file_name, tag_file_name,
				 _("contents not dumped"));
	  break;
	}
    }
}

/* Ensure exactly one trailing slash.  */
static void
ensure_slash (char **pstr)
{
  size_t len = strlen (*pstr);
  while (len >= 1 && ISSLASH ((*pstr)[len - 1]))
    len--;
  if (!ISSLASH ((*pstr)[len]))
    *pstr = xrealloc (*pstr, len + 2);
  (*pstr)[len++] = '/';
  (*pstr)[len] = '\0';
}

static bool
dump_dir (int fd, struct tar_stat_info *st, int top_level, dev_t parent_device)
{
  char *directory = fdsavedir (fd);
  if (!directory)
    {
      savedir_diag (st->orig_file_name);
      return false;
    }

  dump_dir0 (directory, st, top_level, parent_device);

  free (directory);
  return true;
}


/* Main functions of this module.  */

void
create_archive (void)
{
  const char *p;

  open_archive (ACCESS_WRITE);
  buffer_write_global_xheader ();

  if (incremental_option)
    {
      size_t buffer_size = 1000;
      char *buffer = xmalloc (buffer_size);
      const char *q;

      collect_and_sort_names ();

      while ((p = name_from_list ()) != NULL)
	if (!excluded_name (p))
	  dump_file (p, -1, (dev_t) 0);

      blank_name_list ();
      while ((p = name_from_list ()) != NULL)
	if (!excluded_name (p))
	  {
	    size_t plen = strlen (p);
	    if (buffer_size <= plen)
	      {
		while ((buffer_size *= 2) <= plen)
		  continue;
		buffer = xrealloc (buffer, buffer_size);
	      }
	    memcpy (buffer, p, plen);
	    if (! ISSLASH (buffer[plen - 1]))
	      buffer[plen++] = '/';
	    q = gnu_list_name->dir_contents;
	    if (q)
	      while (*q)
		{
		  size_t qlen = strlen (q);
		  if (*q == 'Y')
		    {
		      if (buffer_size < plen + qlen)
			{
			  while ((buffer_size *=2 ) < plen + qlen)
			    continue;
			  buffer = xrealloc (buffer, buffer_size);
 			}
		      strcpy (buffer + plen, q + 1);
		      dump_file (buffer, -1, (dev_t) 0);
		    }
		  q += qlen + 1;
		}
	  }
      free (buffer);
    }
  else
    {
      while ((p = name_next (1)) != NULL)
	if (!excluded_name (p))
	  dump_file (p, 1, (dev_t) 0);
    }

  write_eot ();
  close_archive ();

  if (listed_incremental_option)
    write_directory_file ();
}


/* Calculate the hash of a link.  */
static size_t
hash_link (void const *entry, size_t n_buckets)
{
  struct link const *l = entry;