10 More Discussions You Might Find Interesting
1. Programming
hello, I try to test the POSIX mq_open function on book unp like below:
#include "unpipc.h"
# include <mqueue.h>
int main(int argc, char **argv)
{
int c, flags;
mqd_t mqd;
flags = O_RDWR | O_CREAT;
while ((c = getopt(argc, argv, "e")) != -1) {
... (3 Replies)
Discussion started by: anpufeng
3 Replies
2. Programming
Hi,
I wanted to know whether the POSIX message queues are statically allocated memory by the kernel based on the parameters specified in the open or as and when we send messages, memory are allocated?
Does the kernel reserve the specified memory for the message queue irrespective of whether... (1 Reply)
Discussion started by: sumtata
1 Replies
3. Programming
in a single main() function,so need signal handling. Use Posix Message Queue IPC mechanism , can ignore the priority and other linked list message,to implement the scenario:
client:Knock Knock
server:who's there
client: Eric
Server:Eric,Welcome.
client:exit
all process terminated
... (1 Reply)
Discussion started by: ouou
1 Replies
4. Programming
Hello,
I am trying to implement posix message queue application. I am faced with an error on the mq_receive section. It says "Message too long". I've tried couple of small tweeks, but to no result. Please do suggest any rectificaitons.
mq_send section-works successfully
#include... (2 Replies)
Discussion started by: katwalatapan
2 Replies
5. Linux
Hi all,
Please tell me how to change POSIX message queue maximum size? "ulimit" is not a solution because it controls shell resources. But i need to control queue size before login in and starting the shell. It is needed to limit queue size for applications started before login in.
Sorry for my... (7 Replies)
Discussion started by: Vourhey
7 Replies
6. Programming
Hello,
i need to write a message queue "chat server", that should work only localy.
Can anyone please help me with some ideas and peshaps code. I'm studying the UNIX IPC mechanisms right now. So far, i understand how it works but i still cannot get an idea how to write a chat programm...
... (2 Replies)
Discussion started by: etenv
2 Replies
7. HP-UX
Hello,
My question is related to "pipcs -qa" command under HP-UX 11i PA-RISC 64 bits.
We have a little C program that creates posix ipc message queues using the mq_open() system function.
The program fail with 'No space left on device' error when we create big queues. What is the system... (6 Replies)
Discussion started by: cadanir
6 Replies
8. Programming
hi all...
ive been trying this program where i spawn 4 threads... and i am trying to use message queue to send msgs from 3 of the threads to the parent thread... but it doent seem to be working... ive almost pulled out my hair tryin to fix the prob :confused:
another wierd thing... (1 Reply)
Discussion started by: strider
1 Replies
9. UNIX for Advanced & Expert Users
Hi,
I am working closly with unix message queues i have encountered the following -
after creating the Q and start working with it (pushing & pulling) i receive the following stange parameters on the q's -
STIME=no_entry
Qnum=0
CBYTES=4140
when this happens, the Q is disabled (meaning i... (3 Replies)
Discussion started by: kel
3 Replies
10. Programming
How can I increase the POSIX Msg Q parameter SC_MQ_PRIO_MAX? The maximum is defined as 32. Can I increase the number? If so, how?
Deepa (0 Replies)
Discussion started by: Deepa
0 Replies
mq_getattr(3C) Standard C Library Functions mq_getattr(3C)
NAME
mq_getattr - get message queue attributes
SYNOPSIS
#include <mqueue.h>
int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);
DESCRIPTION
The mqdes argument specifies a message queue descriptor. The mq_getattr() function is used to get status information and attributes of the
message queue and the open message queue description associated with the message queue descriptor. The results are returned in the mq_attr
structure referenced by the mqstat argument.
Upon return, the following members will have the values associated with the open message queue description as set when the message queue
was opened and as modified by subsequent mq_setattr(3C) calls:
mq_flags message queue flags
The following attributes of the message queue are returned as set at message queue creation:
mq_maxmsg maximum number of messages
mq_msgsize maximum message size
mq_curmsgs number of messages currently on the queue.
RETURN VALUES
Upon successful completion, the mq_getattr() function returns 0. Otherwise, the function returns -1 and sets errno to indicate the error.
ERRORS
The mq_getattr() function will fail if:
EBADF The mqdes argument is not a valid message queue descriptor.
ENOSYS The mq_getattr() function is not supported by the system.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
|ATTRIBUTE TYPE |ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
|Standard |See standards(5). |
+-----------------------------+-----------------------------+
SEE ALSO
msgctl(2), msgget(2), msgrcv(2), msgsnd(2), mqueue.h(3HEAD), mq_open(3C), mq_send(3C), mq_setattr(3C), attributes(5), standards(5)
NOTES
Solaris 2.6 was the first release to support the Asynchronous Input and Output option. Prior to this release, this function always returned
-1 and set errno to ENOSYS.
SunOS 5.11 5 Feb 2008 mq_getattr(3C)
How to limit max no of message in a posix message queue