Re: [LTP] [Libtirpc-devel] svcfd_create differences between libtirpc and glibc

[Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>]

CC-in LTP mailing list (I should have do it in the first e-mail)

On 11.03.2014 18:52, Chuck Lever wrote:
>
> On Mar 10, 2014, at 3:34 PM, Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com> wrote:
>
>>
>> On 07.03.2014 18:53, Chuck Lever wrote:
>>>> Is this patch a suitable fix to this bug (sorry for spaces):
>>>>
>>>> diff --git a/src/svc_vc.c b/src/svc_vc.c
>>>> index d65a35e..fcd472d 100644
>>>> --- a/src/svc_vc.c
>>>> +++ b/src/svc_vc.c
>>>> @@ -218,6 +218,12 @@ svc_fd_create(fd, sendsize, recvsize)
>>>>
>>>>         slen = sizeof (struct sockaddr_storage);
>>>>         if (getsockname(fd, (struct sockaddr *)(void *)&ss, &slen) < 0) {
>>>> +               /* if fd is not a network socket, leave the address
>>>> +                * fields unitialized
>>>> +                */
>>>> +               if (errno == ENOTSOCK)
>>>> +                       return ret;
>>>> +
>>>>                 warnx("svc_fd_create: could not retrieve local addr");
>>>>                 goto freedata;
>>>>         }
>>>>
>>>> ?
>>>>
>>>> It works in my case.
>>>>
>>>> Since makefd_xprt() returns a SVCXPRT structure which has xp_ltaddr, xp_rtaddr and xp_raddr filled with zeroes, both xp_ltaddr.buf and xp_rtaddr.buf will point to NULL in my case.
>>>> I suppose, that it should not be an issue, but I'm unsure :)
>>>>
>>>> If it's ok I'll resend it the right way.
>>>
>>> The library now returns an xprt that is not fully initialized. That may not be terribly useful behavior.
>>>
>>> But that seems like the only way to get test-for-test compatibility with glibc. Perhaps the new comment could reflect that.
>>>
>>> Is there any information about exactly what that test is trying to determine? What is fd 0 when that test is run?
>>
>> fd 0 is stdin in the tests. And svcfd_create() function is used to perform a functional testing of itself and other functions (like svc_destroy).
>
> To be clear, I’m not formally objecting to your patch. As a reviewer, I’m just trying to understand whether the proposed fix is appropriate. Thanks for sticking with it!
>

To be clear, I don't insist on applying any changes to the libtirpc 
code. :) In general, I just want to find the failing part. Whether it's 
the test or libtirpc.

>> For example:
>>
>> https://github.com/linux-test-project/ltp/blob/master/testcases/network/rpc/rpc-tirpc-full-test-suite/tests_pack/rpc_suite/rpc/rpc_createdestroy_svcfd_create/1-basic.c
>>
>> and here fd is not explicitly set to 0 (but I'm inclined that this is a bug):
>> https://github.com/linux-test-project/ltp/blob/master/testcases/network/rpc/rpc-tirpc-full-test-suite/tests_pack/rpc_suite/rpc/rpc_createdestroy_svc_destroy/1-basic.c
>
> It would be nice to have some code samples other than test cases so we can see how svcfd_create() is used in the real world. So far, my search results have produced only documentation and header files.
>
> However, this:
>
>    http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=%2Fcom.ibm.aix.progcomm%2Fdoc%2Fprogcomc%2Fstart_rpc_inetd.htm
>
> suggests that svcfd_create() expects a connected TCP socket.
>
> This is why the test case confuses me: Although the inetd daemon would pass fd 0 to svcfd_create(), as the test case does, NULL should be the correct result when passing in a socket that is not a connected TCP socket, I would think.
>
> Is the test program simply run from a terminal, or is it part of some larger infrastructure that would actually provide a TCP socket as fd 0?

This suite has an infrastructure to execute such programs. In general 
the logic is:
* It starts an rpc server like this (in background):
   ./rpc_svc_1 <program number>
   This server registers <program number> and version 1 to rpcbind
* Then it executes a test binary, passing it the host where rpc_svc_1 is 
running and the program number. Like this:
   ./test_binary 127.0.0.1 <program number>
* The test binary do its job and returns/prints either 0 or 1 (success 
or failure).

Of course, there are some variations.

But the programs I mentioned above, in fact, don't perform any calls to 
the running rpc server, therefore they can be executed simply from a 
terminal, therefore (I think), fd is stdin.

So, to sums up, the evil is in the tests and the right action would be 
modifying the tests to pass svcfd_create() a connected TCP socket. Right?

>
> --
> Chuck Lever
> chucklever@gmail.com
>
>
>

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