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Reply-To: jdhedden AT 1979 DOT usna DOT com
From: "Jerry D. Hedden" <jerry AT hedden DOT us>
To: cygwin AT cygwin DOT com
Subject: shmget() not working(?)
Date: Thu, 3 Jun 2004 12:12:11 -0400
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I have cygserver running in the background (default options) on
a W2K box.
CYGWIN is set to 'server'.
The following test program:

#include <sys/shm.h>
#include <errno.h>

int
main(int argc, char **argv)
{
    int pid = fork();
    int id;

    if (pid == 0) {
        sleep(5);
        id = shmget(1, 100, 0666);
        printf("child (%d): %d (%d)\n", getpid(), id, errno);
    } else {
        id = shmget(1, 100, 01666);
        printf("parent (%d): %d (%d)\n", getpid(), id, errno);
        sleep(10);
        shmctl(id, IPC_RMID, 0);
    }

    return (0);
}

Produces the following output:

parent (35492): 196609 (0)
child (3876): 0 (0)

No errors are reported in the cygserver log.

This shows that:
1.  The parent created the shared memory segment and got back its
ID (196609).
2.  The child process tried to attach to the parent's shared memory
segment (using the same key = 1), but shmget() returned 0 with no
error!

Can anyone enlighten me as to what might be wrong?


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