msgctl(2)							   System Calls 							 msgctl(2)

NAME

       msgctl - message control operations

SYNOPSIS

       #include <sys/msg.h>

       int msgctl(int msqid, int cmd, struct msqid_ds *buf);

DESCRIPTION

       The msgctl() function provides a variety of message control operations as specified by cmd. The following cmds are available:

       IPC_STAT        Place  the  current  value of each member of the data structure associated with msqid into the structure pointed to by buf.
		       The contents of this structure are defined in intro(2).

       IPC_SET	       Set the value of the following members of the data structure associated with msqid to the corresponding value found in  the
		       structure pointed to by buf:

		       msg_perm.uid
		       msg_perm.gid
		       msg_perm.mode /* access permission bits only */
		       msg_qbytes

		       This command can be executed only by a process that has either the {PRIV_IPC_OWNER} privilege or an effective user ID equal
		       to the value of msg_perm.cuid or msg_perm.uid in the data  structure  associated  with  msqid.  Only  a	process  with  the
		       {PRIV_SYS_IPC_CONFIG} privilege can raise the value of msg_qbytes.

       IPC_RMID        Remove  the  message  queue  identifier specified by msqid from the system and destroy the message queue and data structure
		       associated with it. This cmd can only be executed by a process that has an effective user ID either with appropriate privi-
		       leges  asserted	in the effective set or equal to the value of msg_perm.cuid or	msg_perm.uid in the data structure associ-
		       ated with msqid.  The buf argument is ignored.

RETURN VALUES

       Upon successful completion, msgctl() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

ERRORS

       The msgctl() function will fail if:

       EACCES	       The cmd argument is IPC_STAT and operation permission is denied to the calling process (see intro(2)).

       EFAULT	       The buf argument points to an illegal address.

       EINVAL	       The msqid argument is not a valid message queue identifier; or the cmd argument is not a valid command or  is  IPC_SET  and
		       msg_perm.uid or msg_perm.gid is not valid.

       EOVERFLOW       The cmd argument is IPC_STAT and uid or gid is too large to be stored in the structure pointed to by buf.

       EPERM	       The  cmd  argument  is  IPC_RMID or IPC_SET, the {PRIV_SYS_IPC_OWNER} privilege is not asserted in the effective set of the
		       calling process, and is not equal to the value of msg_perm.cuid or msg_perm.uid	in  the  data  structure  associated  with
		       msqid.

		       The cmd argument is IPC_SET, an attempt is being made to increase to the value of msg_qbytes, and the {PRIV_SYS_IPC_CONFIG}
		       privilege is not asserted in the effective set of the calling process.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       intro(2), msgget(2), msgrcv(2), msgsnd(2), attributes(5), privileges(5), standards(5)

SunOS 5.10							    22 Mar 2004 							 msgctl(2)