From: Marcus Brinkmann <marcus@gnu.org>
Subject: [PATCH] Implement SysV shared memory for GNU/Hurd.

2005-07-11  Marcus Brinkmann  <marcus@gnu.org>

        * hurd/Makefile (routines): Add sysvshm.
        * hurd/sysvshm.h: New file.
        * hurd/sysvshm.c: New file.
        * sysdeps/mach/hurd/ftok.c: New file.
        * sysdeps/mach/hurd/shmat.c: New file.
        * sysdeps/mach/hurd/shmctl.c: New file.
        * sysdeps/mach/hurd/shmdt.c: New file.
        * sysdeps/mach/hurd/shmget.c: New file.
        * sysdeps/mach/hurd/bits/posix_opt.h: Define _XOPEN_SHM to 1.

TODO:
“
> +  char filename[sizeof (SHM_DIR) - 1 + SHM_NAMEMAX];
> +  struct stat statbuf;
> +
> +  sprintf (filename, SHM_DIR SHM_NAMEPRI, id);
> +  /* SysV requires read access for IPC_STAT.  */
> +  fd = __open (filename, O_NORW);
> +  if (fd < 0)
> +    {
> +      if (errno == ENOENT)
> +     errno = EINVAL;
> +      return -1;
> +    }

Since this is repeated in more than one function, put it into an
internal subroutine.  Then we have only one place doing the
name-generation logic.
”

“
> +    case IPC_RMID:
> +      res = __unlink (filename);
> +      /* FIXME: Check error (mapping ENOENT to EINVAL).  */

Fix it.
”