msgget(PCI)                    6 January 1993                    msgget(PCI)


 Name

    msgget - get message queue

 Syntax


    #include <pcilib.h>


    #include <memmdl.h>


    #include <ipc.h>

    int msgget (key, msgflg)
    key_t key;
    int msgflg;


 Description

    msgget returns the message queue identifier associated with key from the
    UNIX operating system host specified in the most recent dflthost call.

    A message queue identifier and associated message queue and data struc-
    ture (see Intro(PCI)) are created for key if one of the following is
    true:

       key is equal to IPCPRIVATE.

       key does not already have a message queue identifier
       associated with it, and (msgflg & IPCCREAT) is "true."


    Upon creation, the data structure associated with the new message queue
    identifier is initialized as follows:

       Msgperm.cuid, msgperm.uid, msgperm.cgid,
       and msgperm.gid are set to the effective user ID and
       effective group IDs, respectively, of the calling process.

       The low-order nine bits of msgperm.mode are set equal to
       the low-order nine bits of msgflg.

       msgqnum, msglspid, msglrpid,
       msgstime, and msgrtime are set to 0.

       msgctime is set to the current UNIX operating system time.

       msgqbytes is set to the UNIX operating system limit.

    msgget fails if one or more of the following are true:

    [EACCES]  A message queue identifier exists for key, but operation per-
              mission (see Intro(PCI)) as specified by the low-order nine
              bits of msgflg would not be granted.

    [ENOENT]  A message queue identifier does not exist for key, and (msgflg
              & IPCCREAT) is "false."

    [ENOSPC]  A message queue identifier is to be created, but the number of
              message queue identifiers would exceed the system maximum
              allowed for that host.

    [EEXIST]  A message queue identifier exists for key, but (msgflg &
              IPCCREAT) & (msgflg & IPCEXCL) is "true."


 Return value

    On successful completion, a message queue identifier is returned.  Other-
    wise, a value of -1 returns and errno is set to indicate the error.

 See also

    dflthost(PCI), Intro(PCI), msgctl(PCI), msgrcv(PCI), msgsnd(PCI)