Re: grub_strdup() error; or: grub_malloc() zeroes memory?

["Vesa Jääskeläinen" <chaac@nic.fi>]

Colin D Bennett wrote:
> It looks like grub_strdup() does not terminate the returned string with
> a 0 byte.  The only way I could see it working is if grub_malloc()
> filled the returned memory with zeroes.  Does it?
> 
> From kern/misc.c: (circa line 476)
> 
>    char *
>    grub_strdup (const char *s)
>    {
>      grub_size_t len;
>      char *p;
>      
>      len = grub_strlen (s) + 1;
>      p = (char *) grub_malloc (len);
>      if (! p)
>        return 0;
> 
>      return grub_memcpy (p, s, len);
>    }

Zero is copied from source string... notice strlen() + 1.

> But right after that, we have
> 
>    char *
>    grub_strndup (const char *s, grub_size_t n)
>    {
>      grub_size_t len;
>      char *p;
>      
>      len = grub_strlen (s);
>      if (len > n)
>        len = n;
>      p = (char *) grub_malloc (len + 1);
>      if (! p)
>        return 0;
>      
>      grub_memcpy (p, s, len);
>      p[len] = '\0';
>      return p;
>    }
> 
> which explicitly stores a terminating null byte.  If grub_malloc() did
> initialize the memory to zero, then this explicity store would be
> unnecessary.

Here if string is not fully copied there needs to be NUL terminator.