Function sort

src/sort.c:4155–4276

/* Sort NFILES FILES onto OUTPUT_FILE.  Use at most NTHREADS threads.  */

static void
sort (char *const *files, size_t nfiles, char const *output_file,
      size_t nthreads)
{
  struct buffer buf;
  size_t ntemps = 0;
  bool output_file_created = false;

  buf.alloc = 0;

  while (nfiles)
    {
      char const *temp_output;
      char const *file = *files;
      FILE *fp = xfopen (file, "r");
      FILE *tfp;

      size_t bytes_per_line;
      if (nthreads > 1)
        {
          /* Get log P. */
          size_t tmp = 1;
          size_t mult = 1;
          while (tmp < nthreads)
            {
              tmp *= 2;
              mult++;
            }
          bytes_per_line = (mult * sizeof (struct line));
        }
      else
        bytes_per_line = sizeof (struct line) * 3 / 2;

      if (! buf.alloc)
        initbuf (&buf, bytes_per_line,
                 sort_buffer_size (&fp, 1, files, nfiles, bytes_per_line));
      buf.eof = false;
      files++;
      nfiles--;

      while (fillbuf (&buf, fp, file))
        {
          struct line *line;

          if (buf.eof && nfiles
              && (bytes_per_line + 1
                  < (buf.alloc - buf.used - bytes_per_line * buf.nlines)))
            {
              /* End of file, but there is more input and buffer room.
                 Concatenate the next input file; this is faster in
                 the usual case.  */
              buf.left = buf.used;
              break;
            }

          saved_line.text = NULL;
          line = buffer_linelim (&buf);
          if (buf.eof && !nfiles && !ntemps && !buf.left)