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From: Eric Wong <normalperson@yhbt.net>
Newsgroups: gmane.comp.lang.ruby.raindrops.general
Subject: Re: Re: [PATCH] Remove Scope IDs from IPv6 addresses.
Date: Tue, 10 Sep 2013 20:17:06 +0000
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Hleb Valoshka <375gnu@gmail.com> wrote:
> On 9/10/13, Eric Wong <normalperson@yhbt.net> wrote:
> >> +        newaddr = strdup(addr);
> >> +        if (newaddr == NULL)
> >> +                perror("strdup");
> >
> > We'll segfault on strchr below if we perrored above.  If we continue
> > using strdup, I would just use ruby_strdup() (works on both MRI/rbx).
> 
> I haven't use C for a long time, so I thought that strchr checks its args.
> 
> > But I'd rather avoid *strdup entirely.  This is unlikely to
> > remove, right?
> 
> Frankly speaking I dislike functions similar to strdup(), because
> using them you should remember to call free(), sometimes in many
> places (or to use goto). But I'm unfamiliar with internal ruby api, so
> it was the only variant for me.

I try to avoid strdup, too.  I can help you with Ruby C API :)
The advantage of creating Ruby strings right away is it maintains
length, so one can use mem* functions instead of str* functions
(always faster and more explicit, often safer, and never less safe).

> BTW, is anything bad with that variant:
> char *newaddr = alloca(...);
> remove_scope_id(oldaddr, newaddr);

Probably OK in this case, but it would need a comment explaining to stack
checkers the size is bounded and won't overflow.

> > Perhaps something like this (totally untested, likely off-by-one errors)
> 
> Ok, I'll test your code tomorrow.

Thanks.