Re: printf(1) null escape

[Andres Perera]

#include <unistd.h>
#define CMD "/usr/bin/printf"
int
main(void)
{
        execle(CMD, CMD, "\\", NULL, (char *[]){"BROKEN", NULL});
}

On Sat, Apr 2, 2011 at 4:48 AM, Andres Perera <andre...@zoho.com> wrote:
>
> print_escape returns 1 even if it's on null, and the rest of the
> prog just ignores null literals
>
> $ env -i sh -c '/usr/bin/printf \\'
> printf: unknown escape sequence `\'
> PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/local/bin

just to be absolutely clear, printf(1) is the one overstepping into
environ[] because of how it badly handles escapes, not the shell

#include <unistd.h>
#define CMD "/usr/bin/printf"
int
main(void)
{
        execle(CMD, CMD, "\\", NULL, (char *[]){"BROKEN"});
}

here's the plain bug:

$ (./a.out; echo) | vis -l
printf: unknown escape sequence `\'
\^@BROKEN\$

>
> diff -u -r1.17 printf.c
> --- printf.c B  B 27 Oct 2009 23:59:41 -0000 B  B  B 1.17
> +++ printf.c B  B 2 Apr 2011 18:44:36 -0000
> @@ -351,6 +351,11 @@
> B  B  B  B  B  B  B  B putchar('\v');
> B  B  B  B  B  B  B  B break;
>
> + B  B  B  case '\0':
> + B  B  B  B  B  B  B  warnx("null escape sequence");
> + B  B  B  B  B  B  B  rval = 1;
> + B  B  B  B  B  B  B  return 0;
> +
> B  B  B  B default:
> B  B  B  B  B  B  B  B putchar(*str);
> B  B  B  B  B  B  B  B warnx("unknown escape sequence `\\%c'", *str);