fixes in shared memory:

only allow server to create and initialize shared memory,
client will report failure
intercept signals to cleanup shared memory in standalone app, thanks to
Roland Philippsen.

examples/SharedMemory/main.cpp

@@ -22,27 +22,63 @@ subject to the following restrictions:
 #include "../CommonInterfaces/CommonGUIHelperInterface.h"
 #include "SharedMemoryCommon.h"
 
+#include <signal.h>
+#include <err.h>
+#include <stdlib.h>
+
+
+static SharedMemoryCommon*    example = NULL;
+static bool interrupted = false;
+
+#ifndef _WIN32
+#include <unistd.h>
+static void cleanup(int signo)
+{
+    if (interrupted) {  // this is the second time, we're hanging somewhere
+      //  if (example) {
+      //      example->abort();
+      //  }
+        b3Printf("Aborting and deleting SharedMemoryCommon object");
+        sleep(1);
+        delete example;
+        errx(EXIT_FAILURE, "aborted example on signal %d", signo);
+    }
+    interrupted = true;
+    warnx("caught signal %d", signo);
+}
+#endif//_WIN32
+
 
 int main(int argc, char* argv[])
 {
-
+#ifndef _WIN32
+    struct sigaction action;
+    memset(&action, 0x0, sizeof(action));
+    action.sa_handler = cleanup;
+    static const int signos[] = { SIGHUP, SIGINT, SIGQUIT, SIGABRT, SIGSEGV, SIGPIPE, SIGTERM };
+    for (int ii(0); ii < sizeof(signos) / sizeof(*signos); ++ii) {
+        if (0 != sigaction(signos[ii], &action, NULL)) {
+            err(EXIT_FAILURE, "signal %d", signos[ii]);
+        }
+    }
+#endif
+    
 	b3CommandLineArgs args(argc, argv);
 	
 	DummyGUIHelper noGfx;
 
 	CommonExampleOptions options(&noGfx);
-	SharedMemoryCommon*    example = 0;
 
   	if (args.CheckCmdLineFlag("client"))
-        {
-		example = (SharedMemoryCommon*)PhysicsClientCreateFunc(options);
-        }else
-        {
-		example = (SharedMemoryCommon*)PhysicsServerCreateFunc(options);
-        }
+    {
+        example = (SharedMemoryCommon*)PhysicsClientCreateFunc(options);
+    }else
+    {
+        example = (SharedMemoryCommon*)PhysicsServerCreateFunc(options);
+    }
 	
 	example->initPhysics();
-	while (!example->wantsTermination())
+	while (example->isConnected() && !(example->wantsTermination() || interrupted))
 	{
 		example->stepSimulation(1.f/60.f);
 	}