add EPICS_ALLOW_MULTIPLE_IOCS to prevent starting more than one IOC on one machine

src/rsrv/caservertask.c

@@ -34,6 +34,8 @@
 #include "dbEvent.h"
 #include "dbCommon.h"
 #include "epicsStdioRedirect.h"
+#include "epicsExit.h"
+#include "epicsString.h"
 
 #define epicsExportSharedSymbols
 #include "rsrv.h"
@@ -108,6 +110,15 @@ static void req_server (void *pParm)
     if ( status < 0 ) {
         if ( SOCKERRNO == SOCK_EADDRINUSE ||
              SOCKERRNO == SOCK_EACCES ) {
+#ifndef vxWorks
+            const char* multiple_iocs = getenv("EPICS_ALLOW_MULTIPLE_IOCS");
+            if (multiple_iocs && epicsStrCaseCmp(multiple_iocs, "NO") == 0)
+            {
+                errlogPrintf ( "CAS: Default server port %d unavailable.\n" ,ca_server_port);
+                errlogPrintf ( "CAS: Probably already running an IOC on this computer.\n");
+                epicsExit(1);
+            }
+#endif
             /*
              * enable assignment of a default port
              * (so the getsockname() call below will