ioc/db: dbRegisterServer() only warn on actual redefinition

avoid noise when simply run twice.

modules/database/src/ioc/db/dbServer.c

@@ -12,6 +12,7 @@
 #include <stddef.h>
 #include <string.h>
 
+#include "dbDefs.h"
 #include "ellLib.h"
 #include "envDefs.h"
 #include "epicsStdio.h"
@@ -29,6 +30,7 @@ static char *stateNames[] = {
 int dbRegisterServer(dbServer *psrv)
 {
     const char * ignore = envGetConfigParamPtr(&EPICS_IOC_IGNORE_SERVERS);
+    ELLNODE *node;
 
     if (!psrv || !psrv->name || state != registering)
         return -1;
@@ -55,10 +57,14 @@ int dbRegisterServer(dbServer *psrv)
         }
     }
 
-    if (ellNext(&psrv->node) || ellLast(&serverList) == &psrv->node) {
-        fprintf(stderr, "dbRegisterServer: '%s' registered twice?\n",
-            psrv->name);
-        return -1;
+    for(node=ellFirst(&serverList); node; node = ellNext(node)) {
+        dbServer *cur = CONTAINER(node, dbServer, node);
+        if(cur==psrv) {
+            return 0; /* already registered identically. */
+        } else if(strcmp(cur->name, psrv->name)==0) {
+            fprintf(stderr, "dbRegisterServer: Can't redefine '%s'.\n", cur->name);
+            return -1;
+        }
     }
 
     ellAdd(&serverList, &psrv->node);

modules/database/test/ioc/db/dbServerTest.c

@@ -79,6 +79,11 @@ dbServer one = {
     oneInit, oneRun, onePause, oneStop
 };
 
+dbServer one2 = {
+    ELLNODE_INIT, "one",
+    oneReport, oneStats, oneClient,
+    oneInit, oneRun, onePause, oneStop
+};
 
 /* Server layer for testing NULL methods */
 
@@ -123,7 +128,7 @@ MAIN(dbServerTest)
     char *theName = "The One";
     int status;
 
-    testPlan(24);
+    testPlan(25);
 
     /* Prove that we handle substring names properly */
     epicsEnvSet("EPICS_IOC_IGNORE_SERVERS", "none ones");
@@ -132,7 +137,8 @@ MAIN(dbServerTest)
     testOk(dbRegisterServer(&one) == 0, "Registered 'one'");
     testOk1(oneState == NOTHING_CALLED);
 
-    testOk(dbRegisterServer(&one) != 0, "Duplicate registration rejected");
+    testOk(dbRegisterServer(&one) == 0, "Duplicate registration accepted");
+    testOk(dbRegisterServer(&one2) != 0, "change registration rejected");
     testOk(dbRegisterServer(&illegal) != 0, "Illegal registration rejected");
 
     testDiag("Registering dbServer 'no-routines'");