Date: Tue, 10 Jul 2012 17:19:05 +0300 From: Volodymyr Kostyrko <c.kworr@gmail.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, freebsd-standards@FreeBSD.org Subject: Re: kern/149857: [kqueue] kqueue not reporting EOF under certain circumstances Message-ID: <4FFC39D9.6080809@gmail.com> In-Reply-To: <20120710140203.GA2338@deviant.kiev.zoral.com.ua> References: <4FFC1D2D.4020405@gmail.com> <20120710140203.GA2338@deviant.kiev.zoral.com.ua>
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Konstantin Belousov wrote:
>> This PR is rather old. I just had submitted new test case, now in plain c.
>>
>> It doesn't work exactly like python version, but the result is the same:
>>
>>> clang test.c
>>> cat test.c | ./a.out
>> -1 916 0 0 0
>> -1 0 32768 0 0
>>> ./a.out< test.c
>> -1 916 0 0 0
>> <- and here we have a complete hang in [kqread].
>
> And what is your expectation ?
>
> The vnode filter never returns EOF when current file position at the end
> of file. It is documented that read filter returns when file offset if not
> at the end of file, thats all. In fact, EV_EOF is returned on forced unmount.
> I do not see a bug in kqueue.
>
> On the other hand, your C code has at least two things that I cannot
> understand. First, EV_EOF is output flag, it makes absolutely no sense
> to set it in command.Second, it is mistery for me what do you check with
> if (kev.flags>> 15 == 1) {
> test.
EV_EOF on line 19 actually slipped by my fault, original source omits
that one. It doesn't change anything.
EV_EOF = 1 << 15 = 32768. And it _is_ returned when file is feed with
the pipe.
So you mean this is just my false assumption that EOF _should_ occur on
stdin? And it actually occurs only if source is a process which can send
EOF?
--
Sphinx of black quartz judge my vow.
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