From 2bb02e732aa0131f5661a06c9babe00e3466d79d Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Tue, 28 Feb 2017 20:06:42 -0600
Subject: [PATCH] libCom: add errSymMsg() error message lookup

Like errSymLookup() but always returns a static string.
---
 src/libCom/error/errMdef.h   |  1 +
 src/libCom/error/errSymLib.c | 38 ++++++++++++++++++++++++------------
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/libCom/error/errMdef.h b/src/libCom/error/errMdef.h
index e511d912b..163b063f2 100644
--- a/src/libCom/error/errMdef.h
+++ b/src/libCom/error/errMdef.h
@@ -53,6 +53,7 @@ extern "C" {
 #define M_time          (529 <<16) /*epicsTime*/
 
 epicsShareFunc void epicsShareAPI errSymLookup(long status, char *pBuf, unsigned bufLength);
+epicsShareFunc const char* errSymMsg(long status);
 epicsShareFunc void epicsShareAPI errSymTest(unsigned short modnum, unsigned short begErrNum, unsigned short endErrNum);
 epicsShareFunc void epicsShareAPI errSymTestPrint(long errNum);
 epicsShareFunc int epicsShareAPI errSymBld(void);
diff --git a/src/libCom/error/errSymLib.c b/src/libCom/error/errSymLib.c
index f75577b23..74d766810 100644
--- a/src/libCom/error/errSymLib.c
+++ b/src/libCom/error/errSymLib.c
@@ -192,11 +192,9 @@ static void errRawCopy ( long statusToDecode, char *pBuf, unsigned bufLength )
         assert ( nChar < bufLength );
     }
 }
-
-/****************************************************************
- * errSymLookup
- ***************************************************************/
-void epicsShareAPI errSymLookup (long status, char * pBuf, unsigned bufLength)
+
+static
+const char* errSymLookupInternal(long status)
 {
     unsigned modNum;
     unsigned hashInd;
@@ -211,9 +209,7 @@ void epicsShareAPI errSymLookup (long status, char * pBuf, unsigned bufLength)
     if ( modNum <= 500 ) {
         const char * pStr = strerror ((int) status);
         if ( pStr ) {
-            strncpy(pBuf, pStr,bufLength);
-            pBuf[bufLength-1] = '\0';
-            return;
+            return pStr;
         }
     }
     else {
@@ -222,17 +218,35 @@ void epicsShareAPI errSymLookup (long status, char * pBuf, unsigned bufLength)
         pNextNode = *phashnode;
         while(pNextNode) {
             if(pNextNode->errNum==status){
-                strncpy(pBuf, pNextNode->message, bufLength);
-                pBuf[bufLength-1] = '\0';
-                return;
+                return pNextNode->message;
             }
             phashnode = &pNextNode->hashnode;
             pNextNode = *phashnode;
         }
     }
+    return NULL;
+}
+
+const char* errSymMsg(long status)
+{
+    const char* msg = errSymLookupInternal(status);
+    return msg ? msg : "<Unknown code>";
+}
+
+/****************************************************************
+ * errSymLookup
+ ***************************************************************/
+void epicsShareAPI errSymLookup (long status, char * pBuf, unsigned bufLength)
+{
+    const char* msg = errSymLookupInternal(status);
+    if(msg) {
+        strncpy(pBuf, msg, bufLength);
+        pBuf[bufLength-1] = '\0';
+        return;
+    }
     errRawCopy(status, pBuf, bufLength);
 }
-
+
 /****************************************************************
  * errSymDump
  ***************************************************************/