Date: Sat, 5 Mar 2016 20:24:15 +0300 (MSK) From: Alexander Monakov <amonakov@...ras.ru> To: musl@...ts.openwall.com Subject: Re: [PATCH] slim down and avoid undefined behavior in unsetenv On Sat, 5 Mar 2016, Rich Felker wrote: > I don't see much value to it; return __set_errno(e) is functionally > equivalent to return __syscall_ret(-e) and just saves one "neg" > instruction before the tailcall. It might be a nicer abstraction in > places where we don't use syscalls directly, but for the most part > musl avoids internal APIs in those situations anyway, as explained > above. Yeah, I was thinking about using it at call sites that currently do 'errno = Exyz; return -1' for code size improvements; I wasn't aware of why it would be undesired. Thanks for the explanations. > > Here the usage of memcmp requires that it scans buffers left-to-right and > > stops on first mismatch. As I understand the standards do not guarantee that, > > but musl's current implementation does, and is not interposable. Still, a > > gotcha. > > I think you're right. Would it be better to switch such usage to > strncmp then? Given your point about reusability, I think so; were it a place where resulting speed penalty is unwelcome, one could introduce __memcmp_fwd to make the requirement explicitely visible, at zero runtime cost. Alexander
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