The tmpnam() function in libc.a(stdio) runs into an infinite loop
the second time it is called. The problem will occur only if
thje environment variable DJGPP or TEMP ends without a trailing
directory separator.

File src/libc/ansi/stdio/tmpnam.c

The static variable tmp_len is initialized once when the 
tmp_dir variable is retrived from environment variables.
Each time tmpnam() is called, a check is made to see if
the tmp_dir variable ends in a directory separator. If not,
tmp_len is incremented, but tmp_dir is not changed.

To solve the problem, add the directory separator to tmp_dir
inside the if(tmp_dir=0) block.
...
  if (tmp_dir == 0)
  {
    tmp_dir = getenv("TMPDIR");
    if (!tmp_dir || access(tmp_dir, D_OK))
    {
      tmp_dir = getenv("TEMP");
      if (!tmp_dir || access(tmp_dir, D_OK))
      {
	tmp_dir = getenv("TMP");
	if (!tmp_dir || access(tmp_dir, D_OK))
	  tmp_dir = "c:/";
      }
    }
    tmp_len = strlen(tmp_dir);
    if (tmp_dir[tmp_len - 1] != '/' && tmp_dir[tmp_len - 1] != '\' && tmp_dir[tmp_len - 1] != ':')
        tmp_dir[tmp_len++] = '/', tmp_dir[tmp_len] = 0;
  }
...