From f1bb53230744ece7f871d09f733255e5799fecd8 Mon Sep 17 00:00:00 2001
From: Till Straumann <strauman@slac.stanford.edu>
Date: Wed, 10 Sep 2014 12:04:36 -0700
Subject: [PATCH]  - simplified some code  - epicsStackTrace.c provides generic
 epicsStackTraceGetFeatures() testing    the 'epicsBackTrace()' functionality.
 Call out to epicsFindAddrGetFeatures()    to inquire about symbol lookup
 support.

---
 src/libCom/osi/epicsStackTrace.c    | 61 ++++++++++++++---------------
 src/libCom/osi/epicsStackTracePvt.h | 19 ++-------
 2 files changed, 32 insertions(+), 48 deletions(-)

diff --git a/src/libCom/osi/epicsStackTrace.c b/src/libCom/osi/epicsStackTrace.c
index 5480d842a..3bb0cf953 100644
--- a/src/libCom/osi/epicsStackTrace.c
+++ b/src/libCom/osi/epicsStackTrace.c
@@ -7,7 +7,6 @@
  * Author: Till Straumann <strauman@slac.stanford.edu>, 2011, 2014
  */ 
 
-#include <stdarg.h>
 #include <stdlib.h>
 
 #include "epicsStackTracePvt.h"
@@ -41,44 +40,23 @@ static void stackTraceUnlock(void)
 }
 
 static int
-dump(char **buf, int *buf_sz, int *good, const char *fmt, ...)
-{
-va_list ap;
-int rval, put;
-    va_start(ap, fmt);
-        if ( *buf ) {
-            put = rval = vsnprintf(*buf, *buf_sz, fmt, ap);
-            if ( put > *buf_sz )
-                put = *buf_sz;
-            *buf    += put;
-            *buf_sz -= put;
-        } else {
-            rval = errlogVprintf(fmt, ap);
-        }
-    va_end(ap);
-    if ( rval > 0 )
-        *good += rval;
-    return rval;
-}
-
-static int
-symDump(char *buf, int buf_sz, void *addr, epicsSymbol *sym_p)
+dumpInfo(void *addr, epicsSymbol *sym_p)
 {
 int rval = 0;
 
-    dump( &buf, &buf_sz, &rval, "[%*p]", sizeof(addr)*2 + 2, addr);
+	rval += errlogPrintf("[%*p]", (int)(sizeof(addr)*2 + 2), addr);
 	if ( sym_p ) {
 		if ( sym_p->f_nam ) {
-			dump( &buf, &buf_sz, &rval, ": %s", sym_p->f_nam );
+			rval += errlogPrintf(": %s", sym_p->f_nam);
 		}
 		if ( sym_p->s_nam ) {
-			/* windows didn't grok the void* pointer arithmetic */
-			dump( &buf, &buf_sz, &rval, "(%s+0x%lx)", sym_p->s_nam, (unsigned long)((char*)addr - (char*)sym_p->s_val));
+			rval += errlogPrintf("(%s+0x%lx)", sym_p->s_nam, (unsigned long)((char*)addr - (char*)sym_p->s_val));
+		} else {
+			rval += errlogPrintf("(<no symbol information>)");
 		}
 	}
-	dump( &buf, &buf_sz, &rval, "\n");
-	if ( ! buf )
-		errlogFlush();
+	rval += errlogPrintf("\n");
+	errlogFlush();
 
     return rval;
 }
@@ -112,9 +90,9 @@ epicsSymbol sym;
 
 		for ( i=0; i<n; i++ ) {
 			if ( 0 == epicsFindAddr(buf[i], &sym) )
-				symDump(0, 0, buf[i], &sym);
+				dumpInfo(buf[i], &sym);
 			else
-				symDump(0, 0, buf[i], 0);
+				dumpInfo(buf[i], 0);
 		}
 
 		errlogFlush();
@@ -125,3 +103,22 @@ epicsSymbol sym;
 
     free(buf);
 }
+
+int epicsStackTraceGetFeatures()
+{
+void *test[2];
+
+static int initflag = 10; /* init to a value larger than the test snapshot */
+
+	/* don't bother about epicsOnce -- if there should be a race and
+	 * the detection code is executed multiple times that is no big deal.
+	 */
+	if ( 10 == initflag ) {
+		initflag = epicsBackTrace(test, sizeof(test)/sizeof(test[0]));
+	}
+
+	if ( initflag <= 0 )
+		return 0; /* backtrace doesn't work or is not supported */
+
+	return ( EPICS_STACKTRACE_ADDRESSES | epicsFindAddrGetFeatures() );
+}
diff --git a/src/libCom/osi/epicsStackTracePvt.h b/src/libCom/osi/epicsStackTracePvt.h
index 1848f4469..de26044fa 100644
--- a/src/libCom/osi/epicsStackTracePvt.h
+++ b/src/libCom/osi/epicsStackTracePvt.h
@@ -35,25 +35,12 @@ epicsShareFunc int epicsBackTrace(void **buf, int buf_sz);
  *
  * RETURNS: 0 on success, nonzero on failure (not finding an address
  *          is not considered an error).
- *
- * NOTE:    epicsSymbolTableLock() must be held while the string
- *          pointers returned by epicsFindAddr are in use.
- *
- * I.e., 
- *
- *   epicsSymTblLock();
- *
- *     epicsFindAddr( addr, &sym );
- *
- *     do_something( &sym );
- *
- *   epicsSymTblUnlock();
- *
- * epicsSymTblLock() may be implemented by the OSD code such that
- * multiple readers may hold the lock.
  */
 epicsShareFunc int epicsFindAddr(void *addr, epicsSymbol *sym_p);
 
+/* report supported features (as reported by epicsStackTraceGetFeatures) */
+epicsShareFunc int epicsFindAddrGetFeatures();
+
 #ifdef __cplusplus
 }
 #endif