create.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

  uintmax_t num = l->dev ^ l->ino;
  return num % n_buckets;
}

/* Compare two links for equality.  */
static bool
compare_links (void const *entry1, void const *entry2)
{
  struct link const *link1 = entry1;
  struct link const *link2 = entry2;
  return ((link1->dev ^ link2->dev) | (link1->ino ^ link2->ino)) == 0;
}

static void
unknown_file_error (char const *p)
{
  WARN ((0, 0, _("%s: Unknown file type; file ignored"),
	 quotearg_colon (p)));
  if (!ignore_failed_read_option)
    exit_status = TAREXIT_FAILURE;
}


/* Handling of hard links */

/* Table of all non-directories that we've written so far.  Any time
   we see another, we check the table and avoid dumping the data
   again if we've done it once already.  */
static Hash_table *link_table;

/* Try to dump stat as a hard link to another file in the archive.
   Return true if successful.  */
static bool
dump_hard_link (struct tar_stat_info *st)
{
  if (link_table && st->stat.st_nlink > 1)
    {
      struct link lp;
      struct link *duplicate;
      off_t block_ordinal;
      union block *blk;

      lp.ino = st->stat.st_ino;
      lp.dev = st->stat.st_dev;

      if ((duplicate = hash_lookup (link_table, &lp)))
	{
	  /* We found a link.  */
	  char const *link_name = safer_name_suffix (duplicate->name, true,
	                                             absolute_names_option);

	  duplicate->nlink--;

	  block_ordinal = current_block_ordinal ();
	  assign_string (&st->link_name, link_name);
	  if (NAME_FIELD_SIZE - (archive_format == OLDGNU_FORMAT)
	      < strlen (link_name))
	    write_long_link (st);

	  st->stat.st_size = 0;
	  blk = start_header (st);
	  if (!blk)
	    return false;
	  tar_copy_str (blk->header.linkname, link_name, NAME_FIELD_SIZE);

	  blk->header.typeflag = LNKTYPE;
	  finish_header (st, blk, block_ordinal);

	  if (remove_files_option && unlink (st->orig_file_name) != 0)
	    unlink_error (st->orig_file_name);

	  return true;
	}
    }
  return false;
}

static void
file_count_links (struct tar_stat_info *st)
{
  if (hard_dereference_option)
    return;
  if (st->stat.st_nlink > 1)
    {
      struct link *duplicate;
      struct link *lp = xmalloc (offsetof (struct link, name)
				 + strlen (st->orig_file_name) + 1);
      lp->ino = st->stat.st_ino;
      lp->dev = st->stat.st_dev;
      lp->nlink = st->stat.st_nlink;
      strcpy (lp->name, st->orig_file_name);

      if (! ((link_table
	      || (link_table = hash_initialize (0, 0, hash_link,
						compare_links, 0)))
	     && (duplicate = hash_insert (link_table, lp))))
	xalloc_die ();

      if (duplicate != lp)
	abort ();
      lp->nlink--;
    }
}

/* For each dumped file, check if all its links were dumped. Emit
   warnings if it is not so. */
void
check_links (void)
{
  struct link *lp;

  if (!link_table)
    return;

  for (lp = hash_get_first (link_table); lp;
       lp = hash_get_next (link_table, lp))
    {
      if (lp->nlink)
	{
	  WARN ((0, 0, _("Missing links to %s.\n"), quote (lp->name)));
	}
    }
}


/* Dump a single file, recursing on directories.  P is the file name
   to dump.  TOP_LEVEL tells whether this is a top-level call; zero
   means no, positive means yes, and negative means the top level
   of an incremental dump.  PARENT_DEVICE is the device of P's
   parent directory; it is examined only if TOP_LEVEL is zero. */

/* FIXME: One should make sure that for *every* path leading to setting
   exit_status to failure, a clear diagnostic has been issued.  */

static void
dump_file0 (struct tar_stat_info *st, const char *p,
	    int top_level, dev_t parent_device)
{
  union block *header;
  char type;
  off_t original_size;
  struct timespec original_ctime;
  struct timespec restore_times[2];
  off_t block_ordinal = -1;
  bool is_dir;

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

  assign_string (&st->orig_file_name, p);
  assign_string (&st->file_name,
                 safer_name_suffix (p, false, absolute_names_option));

  transform_name (&st->file_name);

  if (deref_stat (dereference_option, p, &st->stat) != 0)
    {
      stat_diag (p);
      return;
    }
  st->archive_file_size = original_size = st->stat.st_size;
  st->atime = restore_times[0] = get_stat_atime (&st->stat);
  st->mtime = restore_times[1] = get_stat_mtime (&st->stat);
  st->ctime = original_ctime = get_stat_ctime (&st->stat);

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

  /* See if we want only new files, and check if this one is too old to
     put in the archive.

     This check is omitted if incremental_option is set *and* the
     requested file is not explicitely listed in the command line. */

  if (!(incremental_option && !is_individual_file (p))
      && !S_ISDIR (st->stat.st_mode)
      && OLDER_TAR_STAT_TIME (*st, m)
      && (!after_date_option || OLDER_TAR_STAT_TIME (*st, c)))
    {
      if (!incremental_option && verbose_option)
	WARN ((0, 0, _("%s: file is unchanged; not dumped"),
	       quotearg_colon (p)));
      return;
    }

  /* See if we are trying to dump the archive.  */
  if (sys_file_is_archive (st))
    {
      WARN ((0, 0, _("%s: file is the archive; not dumped"),
	     quotearg_colon (p)));
      return;
    }

  if (is_avoided_name (p))
    return;

  is_dir = S_ISDIR (st->stat.st_mode) != 0;

  if (!is_dir && dump_hard_link (st))
    return;

  if (is_dir || S_ISREG (st->stat.st_mode) || S_ISCTG (st->stat.st_mode))
    {
      bool ok;
      int fd = -1;
      struct stat final_stat;

      if (is_dir || file_dumpable_p (st))
	{
	  fd = open (p,
		     (O_RDONLY | O_BINARY
		      | (is_dir ? O_DIRECTORY | O_NONBLOCK : 0)
		      | (atime_preserve_option == system_atime_preserve
			 ? O_NOATIME
			 : 0)));
	  if (fd < 0)
	    {
	      if (!top_level && errno == ENOENT)
		WARN ((0, 0, _("%s: File removed before we read it"),
		       quotearg_colon (p)));
	      else
		open_diag (p);
	      return;
	    }
	}

      if (is_dir)
	{
	  const char *tag_file_name;
	  ensure_slash (&st->orig_file_name);
	  ensure_slash (&st->file_name);

	  if (check_exclusion_tags (st->orig_file_name, &tag_file_name)
	      == exclusion_tag_all)
	    {
	      exclusion_tag_warning (st->orig_file_name, tag_file_name,
				     _("directory not dumped"));
	      return;
	    }
	  
	  ok = dump_dir (fd, st, top_level, parent_device);

	  /* dump_dir consumes FD if successful.  */
	  if (ok)
	    fd = -1;
	}
      else
	{
	  enum dump_status status;

	  if (fd != -1 && sparse_option && ST_IS_SPARSE (st->stat))
	    {
	      status = sparse_dump_file (fd, st);
	      if (status == dump_status_not_implemented)
		status = dump_regular_file (fd, st);
	    }
	  else
	    status = dump_regular_file (fd, st);

	  switch (status)
	    {
	    case dump_status_ok:
	    case dump_status_short:
	      mv_end ();
	      file_count_links (st);
	      break;

	    case dump_status_fail:
	      break;

	    case dump_status_not_implemented:
	      abort ();
	    }

	  ok = status == dump_status_ok;
	}

      if (ok)
	{
	  /* If possible, reopen a directory if we are preserving
	     atimes, so that we can set just the atime on systems with
	     _FIOSATIME.  */
	  if (fd < 0 && is_dir
	      && atime_preserve_option == replace_atime_preserve)
	    fd = open (p, O_RDONLY | O_BINARY | O_DIRECTORY | O_NONBLOCK);

	  if ((fd < 0
	       ? deref_stat (dereference_option, p, &final_stat)
	       : fstat (fd, &final_stat))
	      != 0)
	    {
	      stat_diag (p);
	      ok = false;
	    }
	}

      if (ok)
	{
	  if ((timespec_cmp (get_stat_ctime (&final_stat), original_ctime) != 0
	       /* Original ctime will change if the file is a directory and
		  --remove-files is given */
	       && !(remove_files_option && is_dir))
	      || original_size < final_stat.st_size)
	    {
	      WARN ((0, 0, _("%s: file changed as we read it"),
		     quotearg_colon (p)));
	      if (exit_status == TAREXIT_SUCCESS)
		exit_status = TAREXIT_DIFFERS;
	    }
	  else if (atime_preserve_option == replace_atime_preserve
		   && set_file_atime (fd, p, restore_times) != 0)
	    utime_error (p);
	}

      if (0 <= fd && close (fd) != 0)
	{
	  close_diag (p);
	  ok = false;
	}

      if (ok && remove_files_option)
	{
	  if (is_dir)
	    {
	      if (rmdir (p) != 0 && errno != ENOTEMPTY)
		rmdir_error (p);
	    }
	  else
	    {
	      if (unlink (p) != 0)
		unlink_error (p);
	    }
	}

      return;
    }
#ifdef HAVE_READLINK
  else if (S_ISLNK (st->stat.st_mode))
    {
      char *buffer;
      int size;
      size_t linklen = st->stat.st_size;
      if (linklen != st->stat.st_size || linklen + 1 == 0)
	xalloc_die ();
      buffer = (char *) alloca (linklen + 1);
      size = readlink (p, buffer, linklen + 1);
      if (size < 0)
	{
	  readlink_diag (p);
	  return;
	}
      buffer[size] = '\0';
      assign_string (&st->link_name, buffer);
      transform_name (&st->link_name);
      if (NAME_FIELD_SIZE - (archive_format == OLDGNU_FORMAT) < size)
	write_long_link (st);

      block_ordinal = current_block_ordinal ();
      st->stat.st_size = 0;	/* force 0 size on symlink */
      header = start_header (st);
      if (!header)
	return;
      tar_copy_str (header->header.linkname, st->link_name, NAME_FIELD_SIZE);
      header->header.typeflag = SYMTYPE;
      finish_header (st, header, block_ordinal);
      /* nothing more to do to it */

      if (remove_files_option)
	{
	  if (unlink (p) == -1)
	    unlink_error (p);
	}
      file_count_links (st);
      return;
    }
#endif
  else if (S_ISCHR (st->stat.st_mode))
    type = CHRTYPE;
  else if (S_ISBLK (st->stat.st_mode))
    type = BLKTYPE;
  else if (S_ISFIFO (st->stat.st_mode))
    type = FIFOTYPE;
  else if (S_ISSOCK (st->stat.st_mode))
    {
      WARN ((0, 0, _("%s: socket ignored"), quotearg_colon (p)));
      return;
    }
  else if (S_ISDOOR (st->stat.st_mode))
    {
      WARN ((0, 0, _("%s: door ignored"), quotearg_colon (p)));
      return;
    }
  else
    {
      unknown_file_error (p);
      return;
    }

  if (archive_format == V7_FORMAT)
    {
      unknown_file_error (p);
      return;
    }

  block_ordinal = current_block_ordinal ();
  st->stat.st_size = 0;	/* force 0 size */
  header = start_header (st);
  if (!header)
    return;
  header->header.typeflag = type;

  if (type != FIFOTYPE)
    {
      MAJOR_TO_CHARS (major (st->stat.st_rdev),
		      header->header.devmajor);
      MINOR_TO_CHARS (minor (st->stat.st_rdev),
		      header->header.devminor);
    }

  finish_header (st, header, block_ordinal);
  if (remove_files_option)
    {
      if (unlink (p) == -1)
	unlink_error (p);
    }
}

void
dump_file (const char *p, int top_level, dev_t parent_device)
{
  struct tar_stat_info st;
  tar_stat_init (&st);
  dump_file0 (&st, p, top_level, parent_device);
  if (listed_incremental_option)
    update_parent_directory (p);
  tar_stat_destroy (&st);
}