Function fold_file

src/fold.c:158–286

   Return true if successful.  */

static bool
fold_file (char const *filename, size_t width)
{
  FILE *istream;
  size_t column = 0;		/* Screen column where next char will go. */
  idx_t offset_out = 0;		/* Index in 'line_out' for next char. */
  static char line_out[IO_BUFSIZE];
  static char line_in[IO_BUFSIZE];
  mbbuf_t mbbuf;
  int saved_errno;

  if (streq (filename, "-"))
    {
      istream = stdin;
      have_read_stdin = true;
    }
  else
    istream = fopen (filename, "r");

  if (istream == NULL)
    {
      error (0, errno, "%s", quotef (filename));
      return false;
    }

  fadvise (istream, FADVISE_SEQUENTIAL);
  mbbuf_init (&mbbuf, line_in, sizeof line_in, istream);

  mcel_t g;
  while ((g = mbbuf_get_char (&mbbuf)).ch != MBBUF_EOF)
    {
      if (g.ch == '\n')
        {
          write_out (line_out, offset_out, /*newline=*/ true);
          column = offset_out = 0;
          continue;
        }
    rescan:
      column = adjust_column (column, g);

      if (column > width)
        {
          /* This character would make the line too long.
             Print the line plus a newline, and make this character
             start the next line. */
          if (break_spaces)
            {
              int space_length = 0;
              idx_t logical_end = offset_out;
              char *logical_p = line_out;
              char *logical_lim = logical_p + logical_end;

              for (mcel_t g2; logical_p < logical_lim; logical_p += g2.len)
                {
                  g2 = mcel_scan (logical_p, logical_lim);
                  if (c32issep (g2.ch))
                    {
                      space_length = g2.len;