Date: Fri, 15 Jan 1999 12:16:44 +0100 From: Marcel Moolenaar <marcel@scc.nl> To: Brian Feldman <green@unixhelp.org> Cc: Mike Smith <mike@smith.net.au>, freebsd-emulation@FreeBSD.ORG Subject: Re: sendmsg() not working?! Message-ID: <369F239C.D17CD06D@scc.nl> References: <Pine.BSF.4.05.9901141639390.26759-100000@janus.syracuse.net>
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Brian Feldman wrote: > > > > You know of course that system call arguments are faulted in from the user > > > stack on int 0x80, so it doesn't change the system call time that much > > > (read: substantially at all) to have a couple more. > > > > Ok; but the copyout changes data in a structure controlled by the program. > > That change is visible by the program. Technically speaking, the Linux > > emulator can change runtime behavior. I know; it is not likely, but possible. > > That's what bothers me about the copyout. > > I suppose you're right, I saw the const struct msghdr * in sednmsg, but I don't > think that necessarily applies to the cmsg, which is just a pointer in msghdr. > We do not make any changes to the const struct msghdr *, so we violate no > rules. Correct :-) > Why would a program ever check if the sendmsg affected cmsghdr? It is not for the kernel/emulator developer to ask such questions, for it will only result in unfounded assumptions. (hmmm, did I just say that? :-) > All it would do from then on is have the corrct value of cmsg_level. Correct for FreeBSD, but not correct for Linux. We are running Linux apps of course. > If it really bothers anyone any serious amount, there's an easy fix. [fix deleted] I know. It is not such a big deal to spend any more time on this discussion. Let's instead make sure the necessary changed get committed. marcel To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-emulation" in the body of the message
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