Path: utzoo!attcan!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.questions
Subject: Re: How to transfer file descriptors with UNIX domain sockets?
Message-ID: <1990Jul02.125713.7955@virtech.uucp>
Date: 2 Jul 90 12:57:13 GMT
References: <1990Jul01.130157.3627@virtech.uucp> <10981@hydra.gatech.EDU>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 21

In article <10981@hydra.gatech.EDU> gt0178a@prism.gatech.EDU (BURNS,JIM) writes:
>in article <1990Jul01.130157.3627@virtech.uucp>, cpcahil@virtech.uucp (Conor P. Cahill) says:
>>>in article <1421@tub.UUCP>, net@tub.UUCP (Oliver Laumann) says:
>	[code deleted]
>> The system knows because the person, or persons, that added that capability
>> to the sockets code ensured that the file descriptor that was passed became
>> a valid file descriptor in the process that received it.
>
>I'm sure that it *can* be done - my question is what was it in Oliver
>Laumann's code that informed the kernel that what was in the message was a
>file descriptor?

Essentially it is the portion of the that supports the passing of "access
rights".  The access rights to the file descriptor are passed using a
send/recvmsg().  For more info, you could look at section 6.10 "Passing
file descriptors" in UNIX Network Programming (by W. Richard Stevens).

-- 
Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.,
uunet!virtech!cpcahil                           46030 Manekin Plaza, Suite 160
                                                Sterling, VA 22170