unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (SunOS-5.10)
Page:
Section:
Apropos / Subsearch:
optional field

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 exe-
                       cuted by a process that has an effective user ID either
                       with appropriate privileges asserted in  the  effective
                       set   or   equal  to  the  value  of  msg_perm.cuid  or
                       msg_perm.uid in  the  data  structure  associated  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 identi-
                       fier; 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:


       tab()     allbox;     cw(2.750000i)|    cw(2.750000i)    lw(2.750000i)|
       lw(2.750000i).  ATTRIBUTE TYPEATTRIBUTE VALUE Interface  StabilityStan-
       dard


SEE ALSO
       intro(2),   msgget(2),   msgrcv(2),  msgsnd(2),  attributes(5),  privi-
       leges(5), standards(5)



SunOS 5.10                        22 Mar 2004                        msgctl(2)