extract.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

	continue;

      /* Some other error in the mkdir.  We return to the caller.  */
      break;
    }

  return did_something;		/* tell them to retry if we made one */
}

static bool
file_newer_p (const char *file_name, struct tar_stat_info *tar_stat)
{
  struct stat st;

  if (stat (file_name, &st))
    {
      stat_warn (file_name);
      /* Be on the safe side: if the file does exist assume it is newer */
      return errno != ENOENT;
    }
  if (!S_ISDIR (st.st_mode)
      && tar_timespec_cmp (tar_stat->mtime, get_stat_mtime (&st)) <= 0)
    {
      return true;
    }
  return false;
}

/* Attempt repairing what went wrong with the extraction.  Delete an
   already existing file or create missing intermediate directories.
   Return nonzero if we somewhat increased our chances at a successful
   extraction.  errno is properly restored on zero return.  */
static int
maybe_recoverable (char *file_name, int *interdir_made)
{
  int e = errno;

  if (*interdir_made)
    return 0;

  switch (errno)
    {
    case EEXIST:
      /* Remove an old file, if the options allow this.  */

      switch (old_files_option)
	{
	case KEEP_OLD_FILES:
	  return 0;

	case KEEP_NEWER_FILES:
	  if (file_newer_p (file_name, &current_stat_info))
	    {
	      errno = e;
	      return 0;
	    }
	  /* FALL THROUGH */

	case DEFAULT_OLD_FILES:
	case NO_OVERWRITE_DIR_OLD_FILES:
	case OVERWRITE_OLD_FILES:
	  {
	    int r = remove_any_file (file_name, ORDINARY_REMOVE_OPTION);
	    errno = EEXIST;
	    return r;
	  }

	case UNLINK_FIRST_OLD_FILES:
	  break;
	}

    case ENOENT:
      /* Attempt creating missing intermediate directories.  */
      if (! make_directories (file_name))
	{
	  errno = ENOENT;
	  return 0;
	}
      *interdir_made = 1;
      return 1;

    default:
      /* Just say we can't do anything about it...  */

      return 0;
    }
}

/* Fix the statuses of all directories whose statuses need fixing, and
   which are not ancestors of FILE_NAME.  If AFTER_LINKS is
   nonzero, do this for all such directories; otherwise, stop at the
   first directory that is marked to be fixed up only after delayed
   links are applied.  */
static void
apply_nonancestor_delayed_set_stat (char const *file_name, bool after_links)
{
  size_t file_name_len = strlen (file_name);
  bool check_for_renamed_directories = 0;

  while (delayed_set_stat_head)
    {
      struct delayed_set_stat *data = delayed_set_stat_head;
      bool skip_this_one = 0;
      struct stat st;
      struct stat const *cur_info = 0;

      check_for_renamed_directories |= data->after_links;

      if (after_links < data->after_links
	  || (data->file_name_len < file_name_len
	      && file_name[data->file_name_len]
	      && (ISSLASH (file_name[data->file_name_len])
		  || ISSLASH (file_name[data->file_name_len - 1]))
	      && memcmp (file_name, data->file_name, data->file_name_len) == 0))
	break;

      if (check_for_renamed_directories)
	{
	  cur_info = &st;
	  if (stat (data->file_name, &st) != 0)
	    {
	      stat_error (data->file_name);
	      skip_this_one = 1;
	    }
	  else if (! (st.st_dev == data->dev && st.st_ino == data->ino))
	    {
	      ERROR ((0, 0,
		      _("%s: Directory renamed before its status could be extracted"),
		      quotearg_colon (data->file_name)));
	      skip_this_one = 1;
	    }
	}

      if (! skip_this_one)
	{
	  struct tar_stat_info sb;
	  sb.stat.st_mode = data->mode;
	  sb.stat.st_uid = data->uid;
	  sb.stat.st_gid = data->gid;
	  sb.atime = data->atime;
	  sb.mtime = data->mtime;
	  set_stat (data->file_name, &sb, cur_info,
		    data->invert_permissions, data->permstatus, DIRTYPE);
	}

      delayed_set_stat_head = data->next;
      free (data);
    }
}



/* Extractor functions for various member types */

static int
extract_dir (char *file_name, int typeflag)
{
  int status;
  mode_t mode;
  int interdir_made = 0;

  /* Save 'root device' to avoid purging mount points. */
  if (one_file_system_option && root_device == 0)
    {
      struct stat st;
      char *dir = xgetcwd ();

      if (deref_stat (true, dir, &st))
	stat_diag (dir);
      else
	root_device = st.st_dev;
      free (dir);
    }

  if (incremental_option)
    /* Read the entry and delete files that aren't listed in the archive.  */
    purge_directory (file_name);
  else if (typeflag == GNUTYPE_DUMPDIR)
    skip_member ();

  mode = current_stat_info.stat.st_mode | (we_are_root ? 0 : MODE_WXUSR);
  if (0 < same_owner_option || current_stat_info.stat.st_mode & ~ MODE_RWX)
    mode &= S_IRWXU;

  while ((status = mkdir (file_name, mode)))
    {
      if (errno == EEXIST
	  && (interdir_made
	      || old_files_option == DEFAULT_OLD_FILES
	      || old_files_option == OVERWRITE_OLD_FILES))
	{
	  struct stat st;
	  if (stat (file_name, &st) == 0)
	    {
	      if (interdir_made)
		{
		  repair_delayed_set_stat (file_name, &st);
		  return 0;
		}
	      if (S_ISDIR (st.st_mode))
		{
		  mode = st.st_mode;
		  break;
		}
	    }
	  errno = EEXIST;
	}

      if (maybe_recoverable (file_name, &interdir_made))
	continue;

      if (errno != EEXIST)
	{
	  mkdir_error (file_name);
	  return 1;
	}
      break;
    }

  if (status == 0
      || old_files_option == DEFAULT_OLD_FILES
      || old_files_option == OVERWRITE_OLD_FILES)
    {
      if (status == 0)
	delay_set_stat (file_name, &current_stat_info,
			((mode ^ current_stat_info.stat.st_mode)
			 & MODE_RWX & ~ current_umask),
			ARCHIVED_PERMSTATUS);
      else /* For an already existing directory, invert_perms must be 0 */
	delay_set_stat (file_name, &current_stat_info,
			0,
			UNKNOWN_PERMSTATUS);
    }
  return status;
}


static int
open_output_file (char *file_name, int typeflag, mode_t mode)
{
  int fd;
  int openflag = (O_WRONLY | O_BINARY | O_CREAT
		  | (old_files_option == OVERWRITE_OLD_FILES
		     ? O_TRUNC
		     : O_EXCL));

#if O_CTG
  /* Contiguous files (on the Masscomp) have to specify the size in
     the open call that creates them.  */

  if (typeflag == CONTTYPE)
    fd = open (file_name, openflag | O_CTG, mode, current_stat_info.stat.st_size);
  else
    fd = open (file_name, openflag, mode);

#else /* not O_CTG */
  if (typeflag == CONTTYPE)
    {
      static int conttype_diagnosed;

      if (!conttype_diagnosed)
	{
	  conttype_diagnosed = 1;
	  WARN ((0, 0, _("Extracting contiguous files as regular files")));
	}
    }
  fd = open (file_name, openflag, mode);

#endif /* not O_CTG */

  return fd;
}

static int
extract_file (char *file_name, int typeflag)
{
  int fd;
  off_t size;
  union block *data_block;
  int status;
  size_t count;
  size_t written;
  int interdir_made = 0;
  mode_t mode = current_stat_info.stat.st_mode & MODE_RWX & ~ current_umask;
  mode_t invert_permissions =
    0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) : 0;

  /* FIXME: deal with protection issues.  */

  if (to_stdout_option)
    fd = STDOUT_FILENO;
  else if (to_command_option)
    {
      fd = sys_exec_command (file_name, 'f', &current_stat_info);
      if (fd < 0)
	{
	  skip_member ();
	  return 0;
	}
    }
  else
    {
      do
	fd = open_output_file (file_name, typeflag, mode ^ invert_permissions);
      while (fd < 0 && maybe_recoverable (file_name, &interdir_made));

      if (fd < 0)
	{
	  skip_member ();
	  open_error (file_name);
	  return 1;
	}
    }

  mv_begin (&current_stat_info);
  if (current_stat_info.is_sparse)
    sparse_extract_file (fd, &current_stat_info, &size);
  else
    for (size = current_stat_info.stat.st_size; size > 0; )
      {
	mv_size_left (size);

	/* Locate data, determine max length writeable, write it,
	   block that we have used the data, then check if the write
	   worked.  */

	data_block = find_next_block ();
	if (! data_block)
	  {
	    ERROR ((0, 0, _("Unexpected EOF in archive")));
	    break;		/* FIXME: What happens, then?  */
	  }

	written = available_space_after (data_block);

	if (written > size)
	  written = size;
	errno = 0;
	count = full_write (fd, data_block->buffer, written);
	size -= written;

	set_next_block_after ((union block *)
			      (data_block->buffer + written - 1));
	if (count != written)
	  {
	    if (!to_command_option)
	      write_error_details (file_name, count, written);
	    /* FIXME: shouldn't we restore from backup? */
	    break;
	  }
      }

  skip_file (size);

  mv_end ();

  /* If writing to stdout, don't try to do anything to the filename;
     it doesn't exist, or we don't want to touch it anyway.  */

  if (to_stdout_option)
    return 0;

  status = close (fd);
  if (status < 0)
    close_error (file_name);

  if (to_command_option)
    sys_wait_command ();
  else
    set_stat (file_name, &current_stat_info, NULL, invert_permissions,
	      (old_files_option == OVERWRITE_OLD_FILES ?
	       UNKNOWN_PERMSTATUS : ARCHIVED_PERMSTATUS),
	      typeflag);

  return status;
}

/* Create a placeholder file with name FILE_NAME, which will be
   replaced after other extraction is done by a symbolic link if
   IS_SYMLINK is true, and by a hard link otherwise.  Set
   *INTERDIR_MADE if an intermediate directory is made in the
   process.  */

static int
create_placeholder_file (char *file_name, bool is_symlink, int *interdir_made)
{
  int fd;
  struct stat st;

  while ((fd = open (file_name, O_WRONLY | O_CREAT | O_EXCL, 0)) < 0)
    if (! maybe_recoverable (file_name, interdir_made))
      break;

  if (fd < 0)
    open_error (file_name);
  else if (fstat (fd, &st) != 0)
    {
      stat_error (file_name);
      close (fd);
    }
  else if (close (fd) != 0)
    close_error (file_name);
  else
    {
      struct delayed_set_stat *h;
      struct delayed_link *p =
	xmalloc (offsetof (struct delayed_link, target)
		 + strlen (current_stat_info.link_name)
		 + 1);
      p->next = delayed_link_head;
      delayed_link_head = p;
      p->dev = st.st_dev;
      p->ino = st.st_ino;
      p->mtime = get_stat_mtime (&st);
      p->is_symlink = is_symlink;
      if (is_symlink)
	{
	  p->uid = current_stat_info.stat.st_uid;
	  p->gid = current_stat_info.stat.st_gid;
	}
      p->sources = xmalloc (offsetof (struct string_list, string)
			    + strlen (file_name) + 1);
      p->sources->next = 0;
      strcpy (p->sources->string, file_name);
      strcpy (p->target, current_stat_info.link_name);

      h = delayed_set_stat_head;
      if (h && ! h->after_links
	  && strncmp (file_name, h->file_name, h->file_name_len) == 0
	  && ISSLASH (file_name[h->file_name_len])
	  && (last_component (file_name) == file_name + h->file_name_len + 1))
	{
	  do
	    {
	      h->after_links = 1;

	      if (stat (h->file_name, &st) != 0)
		stat_error (h->file_name);
	      else
		{
		  h->dev = st.st_dev;
		  h->ino = st.st_ino;
		}
	    }
	  while ((h = h->next) && ! h->after_links);
	}

      return 0;
    }

  return -1;
}

static int
extract_link (char *file_name, int typeflag)
{
  int interdir_made = 0;
  char const *link_name;

  transform_member_name (&current_stat_info.link_name, xform_link);