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User-Agent: Mozilla/4.72 [en] (X11; U; Linux 2.2.14-5.0 i686)


shm_open does not work w/ glibc 2.2 and Linux 2.4.2 (presumably any 2.4.x
series).  The problem is in
glibc-2.2.2/sysdeps/unix/sysv/linux/linux_fsinfo.h, which defines
SHMEM_SUPER_MAGIC to be 0x02011994.  linux-2.4.2/fs/shmem.c defines
SHMEM_MAGIC to be 0x01021994.  Thus the fix is pretty simple.

I guess this isn't really a RH7.0 problem since it doesn't ship with the
2.4.x kernels, but it is a glibc problem for the current batch of kernels. 
Thus I'm filing it under "enhancement" since this perhaps is just a fix
applicable for the next release of RedHat.



Reproducible: Always
Steps to Reproduce:
Write a simple program:

cat << EOF > foo.c
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>

int
main(int argc, char * const * argv)
{
    int fd;
    fd = shm_open("/blargh", O_RDWR|O_CREAT, 0644);
    if (fd < 0) {
        printf("ERRORERROR!\n");
        abort();
    } else {
        printf("YAY!\n");
        return 0;
    }
}
EOF
cc -D_GNU_SOURCE foo.c -lrt -o foo
./foo


Actual Results:  Prints the error message and dumps core.

Expected Results:  Should have printed yay and returned with 0 exit status.

Also a good idea to add a "none /dev/shm shm defaults 0 0" entry to
/etc/fstab upon installation of a 2.4.x kernel, and mkdir /dev/shm.