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How to limit max no of message in a posix message queue


 
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Old 06-10-2008
Lightbulb How to limit max no of message in a posix message queue

Hii can anyone pls tell how to limit the max no of message in a posix message queue. I have made changes in proc/sys/fs/mqueue/msg_max
But still whenever i try to read the value of max. message in the queue using attr.mq_curmsgs (where struct mq_attr attr) its giving the default value as 10.
can anyone help.

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msgget(2)							   System Calls 							 msgget(2)

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: o key is IPC_PRIVATE. o 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: o 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. o The low-order 9 bits of msg_perm.mode are set to the low-order 9 bits of msgflg. o msg_qnum, msg_lspid, msg_lrpid, msg_stime, and msg_rtime are set to 0. o msg_ctime is set to the current time. o 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 TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ 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. See rctladm(1M) and setrctl(2) for information about using resource controls. SunOS 5.10 11 Feb 2003 msgget(2)

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