posix/mman: update atime on shared memory read call

Update #2859.

cpukit/posix/include/rtems/posix/shmimpl.h

@@ -84,6 +84,15 @@ RTEMS_INLINE_ROUTINE POSIX_Shm_Control *_POSIX_Shm_Get_by_name(
   );
 }
 
+RTEMS_INLINE_ROUTINE void _POSIX_Shm_Update_atime(
+  POSIX_Shm_Control *shm
+)
+{
+  struct timeval now;
+  gettimeofday( &now, 0 );
+  shm->atime = now.tv_sec;
+}
+
 RTEMS_INLINE_ROUTINE void _POSIX_Shm_Update_mtime_ctime(
   POSIX_Shm_Control *shm
 )

cpukit/posix/src/shmopen.c

@@ -66,6 +66,7 @@ static ssize_t shm_read( rtems_libio_t *iop, void *buffer, size_t count )
       buffer,
       count
   );
+  _POSIX_Shm_Update_atime( shm );
   _POSIX_Shm_Release( shm, &queue_context );
 
   return bytes_read;