Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!dinl!noren
From: noren@dinl.uucp (Charles Noren)
Newsgroups: comp.unix.questions
Subject: Sys V Message Queue Question
Summary: Why does it work on one Sun and not on some others?
Keywords: message queues, system V, suns, msgget, msgsnd, msgrcv
Message-ID: <858@dinl.mmc.UUCP>
Date: 15 Mar 89 15:31:44 GMT
Reply-To: noren@dinl.UUCP (Chuck Noren)
Organization: Martin Marietta I&CS, Denver CO.
Lines: 52

On one of our Sun systems (Sun 3/280 with SunOS 4.01) I've got
some C code working using System V Message Queues.  Running
the program to any other of our networked machines (3/50, 3/260) 
with SunOS 4.01) the code fails
on the msgget(2) call to create a non-existant message queue.
errno indicates an invalid argument, which was valid on the
Sun 3/280.  Any ideas on what the problem is an how to fix
it?  Is it a sysgen parameter that needs to be changed to allow
message queues?

Sample code:
    /*
     * Create message queue.
     * Create by also checking the existence of the message queue.
     * If the queue exists, the create attempt will fail.
     *        
     * The flags of the first msgget perform the following:
     *
     *   00600                Set the permissions of the message queue
     *                        for read/write by user only.
     *
     *   IPC_CREAT            Create a message queue (defined in
     *                        <sys/ipc.h>).
     *
     *   IPC_EXCL             Perform the operations only if the message
     *                        queue does not already exist (defined in
     *                        <sys/ipc.h>).
     *
     */

    if((qid = msgget(key, 00600 | IPC_CREAT| IPC_EXCL)) == -1)
    {
        /*
         * ...perform error processing.
         *
         */
    }

key is defined as key_t and I have used values from (key_t) 1 thru (key_t) 30.
The errno I get is 22 (EINVAL -- Invalid argument) when I was expecting
an errno of 17 (EEXIST -- File exists, which is what I get on the Sun
that this stuff works on if the queue already exists).
On the Suns that this does not work I cannot even create a "private"
queue (key = IPC_PRIVATE).

Any help will be appreciated.
-- 
Chuck Noren
NET:     ncar!dinl!noren
US-MAIL: Martin Marietta I&CS, MS XL8058, P.O. Box 1260,
         Denver, CO 80201-1260
Phone:   (303) 971-7930