Yeah, now I understand your problem. How do you check that the error returned by mq_open() ? On which OS do you see this problem?
Thank you for time,
I am giving below the code snippet which i use.
Here rc is returning a value MQ_INVALID Address.
My os details are as follows Fedora Sulphur
Please help me with this,
Thanks again,
Paru.
Last edited by Scott; 11-15-2010 at 02:52 AM..
Reason: Code tags
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)
Hello,
J work on a HP.
I want to create message queue by using mq_open with this parameters:
mq_open(p,O_CREAT|O_WRONLY|O_EXCL|0_NONBLOCK,0600,&queue_attr)
with p char
and the function returns the value -1 and errno equal 2.
can you help me ?
Thank. (3 Replies)
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)
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)
hello,
I had to implement a message queue application....between 30 processes......
all 30 proceses are getting data from serial port....
And here is THE FLOW::::::::1 connector process...which is linked with message queue to all the 30 applications. Processes get the data from serial port and... (9 Replies)
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.... (0 Replies)
Hello !!!!! I have a simple question but i can't find the answer anywhere hope to meet it here.
Why it is a bad idea to pass pointers through message queues ?
Most structs i see all of their char types are arrays... Is it becase having pointers means we could possibily send wrong bytes ?
For... (2 Replies)
Hi guys.
i have wrote a simple program to test message queue attributes. here it is:
#include <stdio.h>
#include <stdlib.h>
#include <mqueue.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
int main()
{
struct mq_attr attr;
mqd_t mqd;
... (2 Replies)
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
LEARN ABOUT V7
brk
BRK(2) System Calls Manual BRK(2)NAME
brk, sbrk, break - change core allocation
SYNOPSIS
char *brk(addr)
char *sbrk(incr)
DESCRIPTION
Brk sets the system's idea of the lowest location not used by the program (called the break) to addr (rounded up to the next multiple of 64
bytes on the PDP11, 256 bytes on the Interdata 8/32, 512 bytes on the VAX-11/780). Locations not less than addr and below the stack
pointer are not in the address space and will thus cause a memory violation if accessed.
In the alternate function sbrk, incr more bytes are added to the program's data space and a pointer to the start of the new area is
returned.
When a program begins execution via exec the break is set at the highest location defined by the program and data storage areas. Ordinar-
ily, therefore, only programs with growing data areas need to use break.
SEE ALSO exec(2), malloc(3), end(3)DIAGNOSTICS
Zero is returned if the break could be set; -1 if the program requests more memory than the system limit or if too many segmentation regis-
ters would be required to implement the break.
BUGS
Setting the break in the range 0177701 to 0177777 (on the PDP11) is the same as setting it to zero.
ASSEMBLER
(break = 17.)
sys break; addr
Break performs the function of brk. The name of the routine differs from that in C for historical reasons.
BRK(2)