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From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
Message-Id: <201801010305.w0135luG084158@pdx.rh.CN85.dnsmgr.net>
Subject: Re: Is it considered to be ok to not check the return code of close(2)
 in base?
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To: Mark Millard <markmi@dsl-only.net>
Date: Sun, 31 Dec 2017 19:05:47 -0800 (PST)
CC: phk@phk.freebsd.dk, FreeBSD Hackers <freebsd-hackers@freebsd.org>
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> Poul-Henning Kamp phk at phk.freebsd.dk wrote on
> Sat Dec 30 20:35:35 UTC 2017 :
> 
> > But if you just close a file, and you're 100% sure that will work,
> > you should write it as:
> > 
> > 	assert(close(fd) == 0);
> > 
> > To tell the rest of us about your assumption and your confidence in it.
> 
> Quoting the FreeBSD assert man page:
> 
> QUOTE
>      The assert() macro	may be removed at compile time by defining NDEBUG as a
>      macro (e.g., by using the cc(1) option -DNDEBUG).
> ENDQUOTE
> 
> This makes required-actions inside asserts dangerous,
> at least without guarantees that NDEBUG will be
> undefined. Trying to guarantee that NDEBUG will be
> undefined would generally be a bad idea.
> 
> So,
> 
> assert(close(fd) == 0);
> 
> is a bad coding practice in my view.

Less bad than either of
	(void)close(fd));
	close(fd);


-- 
Rod Grimes                                                 rgrimes@freebsd.org