Hi!
> > I've been reading POSIX documentation for some time now and even reading
> > glibc source code and the result is that aio_error/3-1.c doesn't test
> > anyting and should be removed.
> >
> > The test is trying to assert EINVAL from aio_error accordingly to:
> >
> > http://www.opengroup.org/onlinepubs/009695399/functions/aio_error.html
> >
> > ...
> >
> > The aio_error() function may fail if:
> >
> > [EINVAL]
> > The aiocbp argument does not refer to an asynchronous
> > operation whose return status has not yet been retrieved.
> >
> > ...
> >
> >
> > As far as I understand this, it's says you may get EINVAL if you call
> > aio_error() on finished aiocb second (and more) times.
> >
> > This is implemented on linux as "return aiocb->__error_code" so IMHO
> > there is no way to test this.
>
> I think that the original developers misinterpreted the test
> requirements. aio_error is _always_ supposed to return errno values,
> not -1 and set the global errno. Otherwise it wouldn't make sense
> because asynchronous I/O would be more synchronous than anything else.
This is not the only problem here. Accordinly to POSIX aio_error() output is
defined only when you pass correct aiocb (that means struct aiocb that is
already used for some aio_{write,read,fsync,...}) and the value may not be
stored pernamently, so if you read it once, it could return EINVAL second time.
...
memset (&aiocb, 0, sizeof (struct aiocb));
aiocb.aio_fildes = fd;
aiocb.aio_buf = buf;
aiocb.aio_reqprio = -1;
aiocb.aio_nbytes = BUF_SIZE;
/*
* Here return from aio_error() is not defined as
* there was no aio operation done on aiocb.
*
* On linux you get value that is stored in struct aiocb->__error_code
* and as aiocb is filled with zeroes on the beginning, this
* returns also zero.
*/
ret = aio_error(&aiocb);
if (aio_write(&aiocb) == -1) {
/* quening write operation has failed */
return 1;
}
/*
* Wait for completion.
*/
while ((ret = aio_error(&aiocb)) == EINPROGRESS)
sleep(1);
/* Here we have status from aio_write in ret */
/*
* And here we may get EINVAL instead of status from previous
* aio_write()
*/
ret = aio_error(&aiocb);
So what I'm saying is that if you really want to write correct test for 3-1.c
you need to:
1. Create aio data transfer
2. Wait for completion
3. Get aio return status by aio_error()
4. Get it once more and it should either be EINVAL or same value that you got
first time.
Which seems to be a little dumb to test to me, so I vote for removing 3-1.c
from ltp.
--
Cyril Hrubis
[email protected]
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