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.

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
         };
 }