Handling of NULL strings by TI C library

C library shipping with TI ARM compiler 5.2.8 handles NULL string pointers passed to the printf family if functions incorrectly.

The bug is in arm_5.2.8/lib/src/_printfi.c, in _pproc_str, line 482:

    /*------------------------------------------------------------------------*/
    /* Handle NULL strings.                                                   */
    /*------------------------------------------------------------------------*/
    if (strbuf == NULL)
    {
       _outc('\0', _op);
       return;
    }

The way it "handles" NULL strings is by inserting a NUL character, which is wrong. Other C libraries either emit nothing or a predefined string, usually "(null)" or some such.

here's a test code snippet:

  char buf[100];
  const char *s = NULL;
  int n = sprintf(buf, "Hello '%s' '%.*s'!", s, 0, s);
  printf("\n%d >%s<\n", n, buf);

on a GNU C library it produces

18 >Hello '(null)' ''!<

On TI library it produces

12 >Hello '<

Also note the behavior when %.* format is used - GNU libc handles it correctly and does not output anything in this case