From 57bbb6651bfc10d9f2404164e3303c3376dfc62c Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Tue, 4 Mar 2008 19:26:24 +0000
Subject: Added backtrace support to the Exception system.  It's pretty simple,
 if it's enabled, and the compiler/libc support it, then you just get
 backtraces, if not you get a message about it not being supported.  It
 probably shouldn't be enabled in most production environments, since it does
 happen for every exception, and could be memory and time consuming.

---
 src/exceptionbase.cpp | 75 +++++++++++++++++++++++++++++++++++++++++++++++----
 src/exceptionbase.h   | 12 +++++++++
 2 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/src/exceptionbase.cpp b/src/exceptionbase.cpp
index 61bbcb4..6e5ae10 100644
--- a/src/exceptionbase.cpp
+++ b/src/exceptionbase.cpp
@@ -11,45 +11,70 @@
 Bu::ExceptionBase::ExceptionBase( const char *lpFormat, ... ) throw() :
 	nErrorCode( 0 ),
 	sWhat( NULL )
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	, sBT( NULL )
+#endif
 {
 	va_list ap;
 
 	va_start(ap, lpFormat);
 	setWhat( lpFormat, ap );
 	va_end(ap);
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	createBacktrace();
+#endif
 }
 
 Bu::ExceptionBase::ExceptionBase( int nCode, const char *lpFormat, ... ) throw() :
 	nErrorCode( nCode ),
 	sWhat( NULL )
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	, sBT( NULL )
+#endif
 {
 	va_list ap;
 
 	va_start(ap, lpFormat);
 	setWhat( lpFormat, ap );
 	va_end(ap);
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	createBacktrace();
+#endif
 }
 
 Bu::ExceptionBase::ExceptionBase( int nCode ) throw() :
 	nErrorCode( nCode ),
 	sWhat( NULL )
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	, sBT( NULL )
+#endif
 {
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	createBacktrace();
+#endif
 }
 
 Bu::ExceptionBase::ExceptionBase( const ExceptionBase &e ) throw () :
 	nErrorCode( e.nErrorCode ),
 	sWhat( NULL )
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	, sBT( NULL )
+#endif
 {
 	setWhat( e.sWhat );
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	createBacktrace();
+#endif
 }
 
 Bu::ExceptionBase::~ExceptionBase() throw()
 {
-	if( sWhat )
-	{
-		delete[] sWhat;
-		sWhat = NULL;
-	}
+	delete[] sWhat;
+	sWhat = NULL;
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+	delete[] sBT;
+	sBT = NULL;
+#endif
 }
 
 void Bu::ExceptionBase::setWhat( const char *lpFormat, va_list &vargs )
@@ -82,3 +107,43 @@ int Bu::ExceptionBase::getErrorCode()
 	return nErrorCode;
 }
 
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+const char *Bu::ExceptionBase::getBacktrace() const throw()
+{
+	return sBT;
+}
+
+#include "bu/fstring.h"
+#include <execinfo.h>
+
+void Bu::ExceptionBase::createBacktrace()
+{
+	void *array[1000];
+	size_t size;
+	char **strings;
+	size_t i;
+	
+	size = backtrace (array, 1000);
+	strings = backtrace_symbols (array, size);
+
+	Bu::FString s;
+	s.format("Obtained %zd stack frames.\n", size );
+
+	for (i = 0; i < size; i++)
+	{
+		s += strings[i];
+		s += "\n";
+	}
+
+	free (strings);
+
+	sBT = new char[s.getSize()+1];
+	strcpy( sBT, s.getStr() );
+}
+
+#else
+const char *Bu::ExceptionBase::getBacktrace() const throw()
+{
+	return "Backtrace support is not compiled in.\n";
+}
+#endif
diff --git a/src/exceptionbase.h b/src/exceptionbase.h
index 391e41d..4d1d2ff 100644
--- a/src/exceptionbase.h
+++ b/src/exceptionbase.h
@@ -12,6 +12,12 @@
 #include <exception>
 #include <stdarg.h>
 
+// This shouldn't normally be defined here, I don't think it's all that portable
+// and it also changes the class interface, we should find out how much of
+// an issue that is, we could just put in an empty getBacktrace() function for
+// when you don't have support for it...
+#define LIBBU_EXCEPTION_BACKTRACE
+
 namespace Bu
 {
 	/**
@@ -83,9 +89,15 @@ namespace Bu
 		 */
 		void setWhat( const char *lpText );
 
+		const char *getBacktrace() const throw();
+
 	private:
 		int nErrorCode;	/**< The code for the error that occured. */
 		char *sWhat;	/**< The text string telling people what went wrong. */
+#ifdef LIBBU_EXCEPTION_BACKTRACE
+		char *sBT;		/**< The backtrace text. */
+		void createBacktrace();
+#endif
 	};
 }
 
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