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Date:      Sat, 30 Dec 2017 21:39:00 +0700
From:      Eugene Grosbein <eugen@grosbein.net>
To:        "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
Cc:        Ian Lepore <ian@freebsd.org>, Yuri <yuri@rawbw.com>, 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:  <5A47A504.1030901@grosbein.net>
In-Reply-To: <201712301406.vBUE68qD076011@pdx.rh.CN85.dnsmgr.net>
References:  <201712301406.vBUE68qD076011@pdx.rh.CN85.dnsmgr.net>

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30.12.2017 21:06, Rodney W. Grimes wrote:

>> Of course, there are cases when that's irrelevant, f.e. closing temporary file
>> that is no more needed and being unlinked anyway.
> 
> No error on close should be treated as irreleveant, they signify something
> has gone wrong and itis best to inform the user and let the user decide
> if this is irrelevant or not.
> 
> Code that does not test return codes from EVERY single thing that can
> return an error should be taken out back shown the danish axe, clean it
> up or get it out of our tree!

An application checks for error code after writing to stderr to report an error
and finds it failed too; and what should be done then? :-)

> One should never code to the "normal" conditions situation, it makes for
> code that does not work well when the "abnormal" conditions arrise.
> 

In real world, there are cases of temporary errors like some transient
system resource shortage; application's own short timeout on close()
because of NFS-server responding slow due to short network malfunction;
temporary DNS failure etc. Not every such case deserves user attention
as system must have some level of self-healing (retry, disregard etc.)

> I would argue that in the above sample of "closing and unlinking" it
> would actually be better to exit if the close failed possibly leaving
> behind the evidence of why/what failed rather than blindling forging
> ahead and potentially destroying the evidecnce by unlinking the file.
>
> If someone wants to go chasing after "failure to check exit codes" please
> begin with /etc/rc.d/*, these scripts are so full of it I laugh every
> time I see a system come up multiuser after 10+ errors have happendend
> in them.

Mostly it is NOT better to halt and sit instead of proceeding to multiuser anyway.




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