man/man2/msgget.2

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 msgget 2 "14 Aug 2006" "SunOS 5.11" "System Calls"
 NAME
msgget - get message queue
 SYNOPSIS

#include <sys/msg.h>

int msgget(key_t key, int msgflg);


 DESCRIPTION

The msgget() argument 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 IPC_PRIVATE.


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


On 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 to the effective user ID and effective group
ID, respectively, of the calling process.


The low-order 9 bits of msg_perm.mode are set to the low-order 9 bits of
msgflg.


msg_qnum, msg_lspid, msg_lrpid, msg_stime, and
msg_rtime are set to 0.


msg_ctime is set to the current time.


msg_qbytes is set to the system limit. See NOTES.

 RETURN VALUES

Upon successful completion, a non-negative integer representing a message queue
identifier is returned. Otherwise, -1 is returned and errno is
set to indicate the error.
 ERRORS

The msgget() function will fail if:

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.


EEXIST

A message queue identifier exists for key but
(msgflg&IPC_CREAT) and (msgflg&IPC_EXCL) are both true.


ENOENT

A message queue identifier does not exist for key and
(msgflg&IPC_CREAT) is false.


ENOSPC

A message queue identifier is to be created but the system-imposed limit on the
maximum number of allowed message queue identifiers system wide would be
exceeded. See NOTES.


 ATTRIBUTES

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


ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard


 SEE ALSO

rctladm(1M), Intro(2), msgctl(2), msgrcv(2),
msgsnd(2), setrctl(2), ftok(3C), attributes(5),
standards(5)
 NOTES

The system-defined limit used to initialize msg_qbytes is the minimum
enforced value of the calling process's process.max-msg-qbytes resource
control.

The system-imposed limit on the number of message queue identifiers is
maintained on a per-project basis using the project.max-msg-ids resource
control. The zone.max-msg-ids resource control restricts the total amount
of message queue identifiers that can be allocated by a zone.

See rctladm(1M) and setrctl(2) for information about using resource
controls.