From d8576826c477f078814103fffe4538cedb6d8895 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Thu, 9 Nov 2017 17:31:44 +0100
Subject: [PATCH] Output an error message when shmat() fails

Observed in #1351 with SELinux as the likely culprit. Without the message, the user saw a segfault with no apparent reason
---
 driver/others/init.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/driver/others/init.c b/driver/others/init.c
index 6efd351ac..855dca929 100644
--- a/driver/others/init.c
+++ b/driver/others/init.c
@@ -78,6 +78,8 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <sys/sysinfo.h>
 #include <sys/syscall.h>
+#include <sys/types.h>
+#include <errno.h>
 #include <sys/shm.h>
 #include <fcntl.h>
 #include <sched.h>
@@ -659,8 +661,9 @@ static void open_shmem(void) {
     exit(1);
   }
 
-  if (shmid != -1) common = (shm_t *)shmat(shmid, NULL, 0);
-
+  if (shmid != -1) {
+  if ( (common = shmat(shmid, NULL, 0)) == (void*)-1) perror ("Attaching shared memory segment");
+  }
 #ifdef DEBUG
   fprintf(stderr, "Shared Memory id = %x  Address = %p\n", shmid, common);
 #endif