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Date:      Wed, 10 Jan 2018 12:12:27 +0100
From:      Stefan Esser <se@freebsd.org>
To:        Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc:        "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>, Eric van Gyzen <eric@vangyzen.net>, Brooks Davis <brooks@freebsd.org>, Ian Lepore <ian@freebsd.org>, Alan Somers <asomers@freebsd.org>, Freebsd hackers list <freebsd-hackers@freebsd.org>, Yuri <yuri@rawbw.com>, Eugene Grosbein <eugen@grosbein.net>
Subject:   Re: Is it considered to be ok to not check the return code of close(2) in base?
Message-ID:  <0ec49613-0eb5-6c6d-f9aa-f88cf4c22659@freebsd.org>
In-Reply-To: <21075.1515581257@critter.freebsd.dk>
References:  <201801081800.w08I0D0q022877@pdx.rh.CN85.dnsmgr.net> <b7d5cc97-2042-42ff-914c-35a28560932b@freebsd.org> <21075.1515581257@critter.freebsd.dk>

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Am 10.01.18 um 11:47 schrieb Poul-Henning Kamp:
> --------
> In message <b7d5cc97-2042-42ff-914c-35a28560932b@freebsd.org>, Stefan Esser wri
> tes:
> 
>>> Ok, so lets get a bit more clever,
>>> #ifdef DEBUG_CLOSE
>>> #define	close(f)	assert(close(f) && errno != EBADF)
>>> #endif
>>
>> This will lead to close() being removed from the program,
>> if NDEBUG is defined ...
>>
>> So, at least test for NDEBUG in addition to DEBUG_CLOSE,
>> to enable this macro.
> 
> More importantly, it will lead to the assert failing if close(2)
> succeeds...

Oh, yes, I missed that detail ;-)

> The NDEBUG details is easiest solved by:
> 
> 	#undef NDEBUG			// assert()'s not to be removed
> 	#include <assert.h>

There has been the much better suggestion by Conrad Meyer (which
uses a GCC extension that might not be supported by CLANG?) and
the LD_PRELOAD hack suggested by Konstantin Belousov, which even
works without recompilation of the program that is to be checked.

I should have read the full thread before replying to a post in
the middle of the discussion ...

Regards, STefan



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