printf(%s) with null pointer

test_format_null.c

/*
  printf(%s) with null pointer

  ## Execute
  $ clang test_format_null.c && ./a.out

  ## Output
  ### OSX
  |(null)||(nu|

  ### Linux with glibc
  |(null)|||
*/

#include <stdio.h>

int main()
{
  printf("|%s|%.0s|%.3s|\n", NULL, NULL, NULL);
  return 0;
}

/*
# Related source
glibc, stdio-common/vfprintf.c
https://sourceware.org/git/?p=glibc.git;a=blob;f=stdio-common/vfprintf.c;h=6829d4dc8e7fe7c066a06f1857ee926e0f48c379;hb=HEAD#l989
*/

// # How it works?
// ## glibc
// 1. REF (form_string), /* for 's', 'S' */
// 2. REF (precision), /* for '.' */
// 3. LABEL (form_string):
// if (string == NULL)
// {
//   /* Write "(null)" if there's space.  */
//   if (prec == -1 || prec >= (int) sizeof (null) - 1)
//   {
//     string = (char *) null;
//     len = sizeof (null) - 1;
//   }
//   else
//   {
//     string = (char *) "";
//     len = 0;
//   }
// }