kern/149857: [kqueue] kqueue not reporting EOF under certain circumstances

Volodymyr Kostyrko c.kworr at
Tue Jul 10 14:19:12 UTC 2012

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 

Sphinx of black quartz judge my vow.

More information about the freebsd-standards mailing list