On Tue, Oct 05, 2021 at 10:54:28AM +0200, Heiko Carstens wrote:
> On Tue, Oct 05, 2021 at 11:18:38AM +0300, Andy Shevchenko wrote:
> > On Mon, Oct 04, 2021 at 10:31:46PM +0200, Heiko Carstens wrote:
> > > On Fri, Oct 01, 2021 at 04:02:01PM +0300, Andy Shevchenko wrote:
...
> > > > + char tmp[8 + 1];
> > > > int i;
> > > >
> > > > - for (i = 0; i < 8; i++) {
> > > > - if (name[i] == '\0')
> > > > - break;
> > > > - dcss_name[i] = toupper(name[i]);
> > > > - }
> > > > - for (; i < 8; i++)
> > > > - dcss_name[i] = ' ';
> > > > + /*
> > > > + * This snprintf() call does two things:
> > > > + * - makes a NUL-terminated copy of the input string
> > > > + * - pads it with spaces
> > > > + */
> > > > + snprintf(tmp, sizeof(tmp), "%s ", name);
> > >
> > > I can't say I like code where I have to count spaces in order to
> > > verify if the code is actually correct.
> >
> > I understand your point, but have any idea how to make it differently
> > and not ugly at the same time?
>
> Don't know. You could use strncopy+strlen+memset (with space
> character). After all I'm not very convinced that the resulting code
> buys us anything compared to the current variant.
Yup, so let's convert only the first part then.
...
> > > > - char dcss_name[9];
> > > > + char dcss_name[8];
> > >
> > > string_upper will copy the terminating NUL-byte. By reducing the size
> > > of dcss_name to 8 bytes this will result in stack corruption.
> >
> > Nope. Even in the original code this additional byte is left unused.
>
> I'm talking about the new code, not the old code: If "name" points to
> a NUL terminated eight chararacter string, then the new code will use
> snprintf to copy it 1:1 to tmp, and the subsequent string_upper() will
> copy the string (upper cased) to dcss_name, now including the NUL
> terminating byte, which won't fit into dcss_name.
> Am I missing something here?
Ah, indeed, although it's rather bug in the implementation of above.
But original code has it not in use.
--
With Best Regards,
Andy Shevchenko
