RE: [PATCH v3 0/4] Make sscanf() stricter

David Laight
2023-06-15T11:40:28Z

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Sent: 15 June 2023 12:24
> ...
>
> > > > What sort of formats and data are being used?
> > >
> > > Base-10 or base-16 integers, with whitespace never being valid.
> >
> > In which case sscanf() really isn't what you are looking for.
> >
> > > > The "%s" format terminates on whitespace.
> > > > Even stroul() (and friends) will skip leading whitespace.
> > >
> > > Yes, which is a reason that strto*l() are just broken IMO.
> >
> > They are not 'broken', that is what is useful most of the time.
> > The usual problem is that "020" is treated as octal.
> >
> > > I’m trying to replace their uses in Xen with custom parsing code.
> >
> > Then write a custom parser :-)
>
> Hmm... Usually we are against zillion implementations of the same with zillion
> bugs hidden (each buggy implementation with its own bugs).

Using strtoull() for the actual numeric conversion removes most of that.

I am intrigued about why you want to error leading whitespace.
I bet you'll find something that is passing space-padded input.
It might be against the letter of the spec - but it doesn't mean
it doesn't happen.

David

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