du.c

Linux.Programming.by example 的源代码绝对经典

	  && 1 < sb->st_nlink
	  && hash_ins (sb->st_ino, sb->st_dev)))
    {
      /* Note that we must not simply return here.
	 We still have to update prev_level and maybe propagate
	 some sums up the hierarchy.  */
      size = 0;
      print = 0;
    }
  else
    {
      size = (apparent_size
	      ? sb->st_size
	      : ST_NBLOCKS (*sb) * ST_NBLOCKSIZE);
    }

  if (first_call)
    {
      n_alloc = info->level + 10;
      sum_ent = XCALLOC (uintmax_t, n_alloc);
      sum_subdir = XCALLOC (uintmax_t, n_alloc);
    }
  else
    {
      /* FIXME: it's a shame that we need these `size_t' casts to avoid
	 warnings from gcc about `comparison between signed and unsigned'.
	 Probably unavoidable, assuming that the members of struct FTW
	 are of type `int' (historical), since I want variables like
	 n_alloc and prev_level to have types that make sense.  */
      if (n_alloc <= (size_t) info->level)
	{
	  n_alloc = info->level * 2;
	  sum_ent = XREALLOC (sum_ent, uintmax_t, n_alloc);
	  sum_subdir = XREALLOC (sum_subdir, uintmax_t, n_alloc);
	}
    }

  size_to_print = size;

  if (! first_call)
    {
      if ((size_t) info->level == prev_level)
	{
	  /* This is usually the most common case.  Do nothing.  */
	}
      else if ((size_t) info->level > prev_level)
	{
	  /* Descending the hierarchy.
	     Clear the accumulators for *all* levels between prev_level
	     and the current one.  The depth may change dramatically,
	     e.g., from 1 to 10.  */
	  int i;
	  for (i = prev_level + 1; i <= info->level; i++)
	    sum_ent[i] = sum_subdir[i] = 0;
	}
      else /* info->level < prev_level */
	{
	  /* Ascending the hierarchy.
	     nftw processes a directory only after all entries in that
	     directory have been processed.  When the depth decreases,
	     propagate sums from the children (prev_level) to the parent.
	     Here, the current level is always one smaller than the
	     previous one.  */
	  assert ((size_t) info->level == prev_level - 1);
	  size_to_print += sum_ent[prev_level];
	  if (!opt_separate_dirs)
	    size_to_print += sum_subdir[prev_level];
	  sum_subdir[info->level] += (sum_ent[prev_level]
				      + sum_subdir[prev_level]);
	}
    }

  prev_level = info->level;
  first_call = 0;

  /* Let the size of a directory entry contribute to the total for the
     containing directory, unless --separate-dirs (-S) is specified.  */
  if ( ! (opt_separate_dirs && IS_FTW_DIR_TYPE (file_type)))
    sum_ent[info->level] += size;

  /* Even if this directory is unreadable or we can't chdir into it,
     do let its size contribute to the total, ... */
  tot_size += size;

  /* ... but don't print out a total for it, since without the size(s)
     of any potential entries, it could be very misleading.  */
  if (file_type == FTW_DNR || file_type == FTW_DCH)
    return 0;

  /* If we're not counting an entry, e.g., because it's a hard link
     to a file we've already counted (and --count-links), then don't
     print a line for it.  */
  if (!print)
    return 0;

  /* FIXME: This looks suspiciously like it could be simplified.  */
  if ((IS_FTW_DIR_TYPE (file_type) &&
		     (info->level <= max_depth || info->level == 0))
      || ((opt_all && info->level <= max_depth) || info->level == 0))
    {
      print_only_size (size_to_print);
      fputc ('\t', stdout);
      if (arg_length)
	{
	  /* Print the file name, but without the `.' or `/.'
	     directory suffix that we may have added in main.  */
	  /* Print everything before the part we appended.  */
	  fwrite (file, arg_length, 1, stdout);
	  /* Print everything after what we appended.  */
	  fputs (file + arg_length + suffix_length
		 + (file[arg_length + suffix_length] == '/'), stdout);
	}
      else
	{
	  fputs (file, stdout);
	}
      fputc ('\n', stdout);
      fflush (stdout);
    }

  return 0;
}

static int
is_symlink_to_dir (char const *file)
{
  char *f;
  struct stat sb;

  ASSIGN_STRDUPA (f, file);
  strip_trailing_slashes (f);
  return (lstat (f, &sb) == 0 && S_ISLNK (sb.st_mode)
	  && stat (f, &sb) == 0 && S_ISDIR (sb.st_mode));
}

/* Recursively print the sizes of the directories (and, if selected, files)
   named in FILES, the last entry of which is NULL.
   FTW_FLAGS controls how nftw works.
   Return nonzero upon error.  */

static int
du_files (char **files, int ftw_flags)
{
  int fail = 0;
  int i;
  for (i = 0; files[i]; i++)
    {
      char *file = files[i];
      char *orig = file;
      int err;
      arg_length = 0;

      if (!print_totals)
	hash_clear (htab);

      /* When dereferencing only command line arguments, we're using
	 nftw's FTW_PHYS flag, so a symlink-to-directory specified on
	 the command line wouldn't normally be dereferenced.  To work
	 around that, we incur the overhead of appending `/.' (or `.')
	 now, and later removing it each time we output the name of
	 a derived file or directory name.  */
      if (opt_dereference_arguments && is_symlink_to_dir (file))
	{
	  size_t len = strlen (file);
	  /* Append `/.', but if there's already a trailing slash,
	     append only the `.'.  */
	  char const *suffix = (file[len - 1] == '/' ? "." : "/.");
	  char *new_file;
	  suffix_length = strlen (suffix);
	  new_file = xmalloc (len + suffix_length + 1);
	  memcpy (mempcpy (new_file, file, len), suffix, suffix_length + 1);
	  arg_length = len;
	  file = new_file;
	}

      err = nftw (file, process_file, MAX_N_DESCRIPTORS, ftw_flags);
      if (err)
	error (0, errno, "%s", quote (orig));
      fail |= err;

      if (arg_length)
	free (file);
    }

  if (print_totals)
    print_size (tot_size, _("total"));

  return fail;
}

int
main (int argc, char **argv)
{
  int c;
  char *cwd_only[2];
  int max_depth_specified = 0;
  char **files;
  int fail;

  /* Bit flags that control how nftw works.  */
  int ftw_flags = FTW_DEPTH | FTW_PHYS | FTW_CHDIR;

  /* If nonzero, display only a total for each argument. */
  int opt_summarize_only = 0;

  cwd_only[0] = ".";
  cwd_only[1] = NULL;

  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  exclude = new_exclude ();

  human_output_opts = human_options (getenv ("DU_BLOCK_SIZE"), false,
				     &output_block_size);

  fail = 0;
  while ((c = getopt_long (argc, argv, "abchHklmsxB:DLSX:", long_options, NULL))
	 != -1)
    {
      long int tmp_long;
      switch (c)
	{
	case 0:			/* Long option. */
	  break;

	case 'a':
	  opt_all = 1;
	  break;

	case APPARENT_SIZE_OPTION:
	  apparent_size = 1;
	  break;

	case 'b':
	  apparent_size = 1;
	  human_output_opts = 0;
	  output_block_size = 1;
	  break;

	case 'c':
	  print_totals = 1;
	  break;

	case 'h':
	  human_output_opts = human_autoscale | human_SI | human_base_1024;
	  output_block_size = 1;
	  break;

	case 'H':
	  human_output_opts = human_autoscale | human_SI;
	  output_block_size = 1;
	  break;

	case 'k':
	  human_output_opts = 0;
	  output_block_size = 1024;
	  break;

	case MAX_DEPTH_OPTION:		/* --max-depth=N */
	  if (xstrtol (optarg, NULL, 0, &tmp_long, NULL) == LONGINT_OK
	      && 0 <= tmp_long && tmp_long <= INT_MAX)
	    {
	      max_depth_specified = 1;
	      max_depth = (int) tmp_long;
	    }
	  else
	    {
	      error (0, 0, _("invalid maximum depth %s"),
		     quote (optarg));
	      fail = 1;
	    }
 	  break;

	case 'm': /* obsolescent */
	  human_output_opts = 0;
	  output_block_size = 1024 * 1024;
	  break;

	case 'l':
	  opt_count_all = 1;
	  break;

	case 's':
	  opt_summarize_only = 1;
	  break;

	case 'x':
	  ftw_flags |= FTW_MOUNT;
	  break;

	case 'B':
	  human_output_opts = human_options (optarg, true, &output_block_size);
	  break;

	case 'D':
	  opt_dereference_arguments = 1;
	  break;

	case 'L':
	  ftw_flags &= ~FTW_PHYS;
	  break;

	case 'S':
	  opt_separate_dirs = 1;
	  break;

	case 'X':
	  if (add_exclude_file (add_exclude, exclude, optarg,
				EXCLUDE_WILDCARDS, '\n'))
	    {
	      error (0, errno, "%s", quotearg_colon (optarg));
	      fail = 1;
	    }
	  break;

	case EXCLUDE_OPTION:
	  add_exclude (exclude, optarg, EXCLUDE_WILDCARDS);
	  break;

	case_GETOPT_HELP_CHAR;

	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

	default:
	  fail = 1;
	}
    }

  if (fail)
    usage (EXIT_FAILURE);

  if (opt_all && opt_summarize_only)
    {
      error (0, 0, _("cannot both summarize and show all entries"));
      usage (EXIT_FAILURE);
    }

  if (opt_summarize_only && max_depth_specified && max_depth == 0)
    {
      error (0, 0,
	     _("warning: summarizing is the same as using --max-depth=0"));
    }

  if (opt_summarize_only && max_depth_specified && max_depth != 0)
    {
      error (0, 0,
	     _("warning: summarizing conflicts with --max-depth=%d"),
	       max_depth);
      usage (EXIT_FAILURE);
    }

  if (opt_summarize_only)
    max_depth = 0;

  files = (optind == argc ? cwd_only : argv + optind);

  /* Initialize the hash structure for inode numbers.  */
  hash_init ();

  exit (du_files (files, ftw_flags) || G_fail
	? EXIT_FAILURE : EXIT_SUCCESS);
}