I dont hardcode the key but rely on the kernel giving me a unique value for it. That's why 5000 threw me off because I took it to be the segment size requested.
Try shmget(IPC_PRIVATE, sizeof(int), 0777) but if you want to hardcode shmid then try...
I have installed an application that runs correctly for root but not other users. The application generates an error that indicates users don't have permission to attach to shared memory. A daemon process creates the shared memory segment. I've checked every permission I can think of but nothing... (2 Replies)
The first shmat in my program cannot fetch the start address of the shared memory.
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
int main(int argc,char *argv) {
int pid;
key_t mykey;
int shmid;
long *shm;
long *shm2;
... (3 Replies)
Hi,
I'm developing a data processing pipeline with multiple stages, with data being moved between the stages using shared memory segments. The size of the data is typically of the order of hundreds of megabytes, and there are typically a few tens of main shared memory segments each of size... (2 Replies)
I have a process that needs two active connections to the same zone of shared memory simultaneously.
The firs conection works ok, but when i do the second call to shmat it give me error 22 (EINVAL). Only works ok the second call to shmat if i disconnect the first connection (shmdt)
Steps:... (3 Replies)
request_irq always returns EINVAL
What am I doing wrong here ?
int mydrvr_open(struct inode *inode, struct file *filp)
{
int ret;
printk("<1> \nModule Opened!");
//disable_irq(4);
//free_irq(4, NULL);
ret = request_irq(4, &imr_interrupt_handler,IRQF_SHARED,... (0 Replies)
Hi,
I'm using Ubuntu 10.04 on a 64bit machine.
In my shmat() call, I want to assign fixed memory address to shmaddr variable. I have no idea which address value to give. Some where in the net I read we can make use of sysproc info to know the user space addresses, but could not figure out how... (1 Reply)
Hi,
My program was running for a whole night. after 12 hours i got an error message "Cannot allocate memory" during the shmat commmand. So can you please let me know what could be the reason? is there any solution?
thanks in advance.
Regards,
Mano (5 Replies)
Hello,
I have another problem with my script. Please accept my apologies, but I am really nooby in sh scripts. I am writing it for first time.
My script:
returned=`tail -50 SapLogs.log | grep -i "Error"`
echo $returned
if ; then
echo "There is no errors in the logs"
fi
And after... (10 Replies)
Hi
Below script is throwing an error:
repos=root
filename=/home/admin/Desktop/authz
case $repos in
root)
root_folder="\"
do
sed "/$root_folder/a $username = $access" $filename
done
;;
esac
exit 0
Error:
./new1.sh: line 77: syntax error near unexpected token `do' (1 Reply)
Discussion started by: ankur328
1 Replies
LEARN ABOUT NETBSD
shmget
SHMGET(2) BSD System Calls Manual SHMGET(2)NAME
shmget -- get shared memory segment
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/shm.h>
int
shmget(key_t key, size_t size, int shmflg);
DESCRIPTION
shmget() returns the shared memory identifier associated with the key key.
A shared memory segment is created if either key is equal to IPC_PRIVATE, or key does not have a shared memory segment identifier associated
with it, and the IPC_CREAT bit is set in shmflg. If both the IPC_CREAT bit and the IPC_EXCL bit are set in shmflg, and key has a shared mem-
ory segment identifier associated with it already, the operation will fail.
If a new shared memory segment is created, the data structure associated with it (the shmid_ds structure, see shmctl(2)) is initialized as
follows:
o shm_perm.cuid and shm_perm.uid are set to the effective uid of the calling process.
o shm_perm.gid and shm_perm.cgid are set to the effective gid of the calling process.
o shm_perm.mode is set to the lower 9 bits of shmflg.
o shm_lpid, shm_nattch, shm_atime, and shm_dtime are set to 0.
o shm_ctime is set to the current time.
o shm_segsz is set to the value of size.
RETURN VALUES
Upon successful completion a positive shared memory segment identifier is returned. Otherwise, -1 is returned and the global variable errno
is set to indicate the error.
ERRORS
[EACCES] A shared memory segment is already associated with key and the caller has no permission to access it.
[EEXIST] Both IPC_CREAT and IPC_EXCL are set in shmflg, and a shared memory segment is already associated with key.
[EINVAL] No shared memory segment is to be created, and a shared memory segment exists for key, but the size of the segment associ-
ated with it is less than size, which is non-zero.
A shared memory segment is to be created, and size is less than the system imposed minimum, or greater than the system
imposed maximum (refer to the kern.ipc values in sysctl(7)).
[ENOENT] IPC_CREAT is not set in shmflg and no shared memory segment associated with key was found.
[ENOMEM] There is not enough memory left to create a shared memory segment of the requested size.
[ENOSPC] A new shared memory identifier could not be created because the system limit for the number of shared memory identifiers
has been reached.
SEE ALSO ipcrm(1), ipcs(1), mmap(2), shmat(2), shmctl(2), ftok(3), sysctl(7)STANDARDS
The shmget system call conforms to X/Open System Interfaces and Headers Issue 5 (``XSH5'').
HISTORY
Shared memory segments appeared in the first release of AT&T System V UNIX.
BSD October 27, 2008 BSD