MSGGET(2) DOMAIN/IX Reference Manual (SYS5) MSGGET(2)
NAME
msgget - get message queue
USAGE
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
int msgget (key, msgflg)
key_t key;
int msgflg;
DESCRIPTION
Msgget returns the message queue identifier associated with
key.
A message queue identifier and associated message queue and
data structure (see intro(2)) are created for key if one of
the following are true:
Key is equal to IPC_PRIVATE.
Key does not already have a message queue identifier
associated with it, and (msgflg & IPC_CREAT) is
``true''.
Upon creation, the data structure associated with the new
message queue identifier is initialized as follows:
Msg_perm.cuid, msg_perm.uid, msg_perm.cgid, and
msg_perm.gid are set equal to the effective user ID and
effective group ID, respectively, of the calling pro-
cess.
The low-order 9 bits of msg_perm.mode are set equal to
the low-order 9 bits of msgflg.
Msg_qnum, msg_lspid, msg_lrpid, msg_stime, and
msg_rtime are set equal to 0.
Msg_ctime is set equal to the current time.
Msg_qbytes is set equal to the system limit.
RETURN VALUE
Upon successful completion, msgctl returns a non-negative
integer, namely the message queue identifier. Otherwise, a
value of -1 is returned and errno is set to indicate the
error.
ERRORS
Msgget will fail if one or more of the following are true:
Printed 5/10/85 MSGGET-1
MSGGET(2) DOMAIN/IX Reference Manual (SYS5) MSGGET(2)
[EACCES] A message queue identifier exists for key,
but operation permission (see intro(2)) as
specified by the low-order 9 bits of msgflg
would not be granted.
[ENOENT] A message queue identifier does not exist for
key and (msgflg & IPC_CREAT) is ``false''.
[ENOSPC] The system-imposed limit on the maximum
number of allowed message queue identifiers
system-wide would be exceeded.
[EEXIST] A message queue identifier exists for key but
( (msgflg & IPC_CREAT) & ( msgflg & IPC_EXCL)
) is ``true''.
RELATED INFORMATION
msgctl(2), msgop(2)
MSGGET-2 Printed 5/10/85