Date: Mon, 8 Jan 2018 10:00:13 -0800 (PST) From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> To: Eric van Gyzen <eric@vangyzen.net> Cc: Eugene Grosbein <eugen@grosbein.net>, Yuri <yuri@rawbw.com>, Brooks Davis <brooks@freebsd.org>, Ian Lepore <ian@freebsd.org>, Alan Somers <asomers@freebsd.org>, Freebsd hackers list <freebsd-hackers@freebsd.org> Subject: Re: Is it considered to be ok to not check the return code of close(2) in base? Message-ID: <201801081800.w08I0D0q022877@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <df6f98a5-76db-d6d8-6321-d35b59eeec22@vangyzen.net>
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> On 01/08/2018 10:55, Rodney W. Grimes wrote: > >> 08.01.2018 23:13, Eric van Gyzen wrote: > >> > >>> Right, which is the reason such bugs are hard to diagnose. Optionally > >>> killing the process on close->EBADF would help find buggy code when > >>> another thread did NOT re-open the file descriptor between the two close > >>> calls. > >> > >> Wouldn't "close(f); assert(errno != EBADF);" be better? > > Putting the code in one place is far better than putting it in N > places...after /finding/ those N places. Indeed, the purpose of this > code is to help people find those places, even in their own code, > outside of base. I agree with that. > > Or even > > #ifdef DEBUG_CLOSE > > #define close(f) close(f); assert(errno != EBADF); > > #endif > > errno could have been EBADF before the close(). A successful close() > does not modify errno. So, this would have be larger, making it even > more unpalatable. Ok, so lets get a bit more clever, #ifdef DEBUG_CLOSE #define close(f) assert(close(f) && errno != EBADF) #endif There, now only if close failed do we check errno, how does that work for you? And if it doesnt I am sure you can code up a #define that does work well. > > > Then the people that want to go chasing these errors can, > > and the rest of us are untouched. > > Every mention in this thread of killing the process has called it > optional. Tools, not policy. I am not certain on that, I think some of the proposals seemed to make the change non optional, but maybe I was reading too much between the lines. -- Rod Grimes rgrimes@freebsd.org
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