On Monday 07 December 2009, Shawn O. Pearce wrote:
> Johan Herland <johan@xxxxxxxxxxx> wrote:
> > +static unsigned char convert_num_notes_to_fanout(uintmax_t num_notes)
> > +{
> > + unsigned char fanout = 0;
> > + while ((num_notes >>= 8))
> > + fanout++;
> > + return fanout;
> > +}
> > +
> > +static void construct_path_with_fanout(const char *hex_sha1,
> > + unsigned char fanout, char *path)
> > +{
> > + unsigned int i = 0, j = 0;
> > + if (fanout >= 20)
> > + die("Too large fanout (%u)", fanout);
>
> Shouldn't convert_num_notes_to_fanout have a guard to prevent this
> case from happening?
Well, it sort of already does (unless uintmax_t is more than 19 * 8 = 152
bits wide... ;)
Not sure what you're getting at:
- Should I add a "&& fanout < 19" condition to the while loop in
convert_num_notes_to_fanout()?
- Should I remove the "if (fanout >= 20) die(...)"? Of course,
construct_path_with_fanout() is only supposed to be called with values
returned from convert_num_notes_to_fanout(), so the condition only tests a
precondition that we believe to be true (FTR, it was converted from an
equivalent assert() in an earlier iteration), but I normally test for these
things anyway (when they are not blindingly obvious), just to make sure...
(and I believe a die(...) is kinder to the user than a segfault...)
...Johan
--
Johan Herland, <johan@xxxxxxxxxxx>
www.herland.net
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