add exception backtraces for segfaults and fatal errors.

Rakefile

@@ -9,7 +9,7 @@ manifest.exclude "ext/**/test/*", "ext/**/test/*", "ext/**/samples/*", "ext/**/b
 Gem::Specification.new do |gemspec|
   $gemspec = gemspec
   gemspec.name = gemspec.rubyforge_project = "therubyracer"
-  gemspec.version = "0.6.1"
+  gemspec.version = "0.7.0"
   gemspec.summary = "Embed the V8 Javascript interpreter into Ruby"
   gemspec.description = "Call javascript code and manipulate javascript objects from ruby. Call ruby code and manipulate ruby objects from javascript."
   gemspec.email = "cowboyd@thefrontside.net"
@@ -41,11 +41,14 @@ task :clean do
   sh "rm -rf lib/v8/*.bundle lib/v8/*.so"
 end
 
-namespace :clean do
-  desc "remove all built v8 objects"
-  task "v8" => "clean" do
-    sh "cd #{UPSTREAM} && make clean"
-  end  
+desc "remove all built v8 objects"
+task "v8:clean" => "clean" do
+  sh "cd #{UPSTREAM} && make clean"
+end
+
+desc "build v8 with debugging symbols (much slower)"
+task "v8:debug" do
+  sh "cd #{UPSTREAM} && make debug"
 end
 
 for file in Dir['tasks/*.rake']

ext/v8/extconf.rb

@@ -14,6 +14,8 @@ have_library('pthread')
 have_library('objc') if RUBY_PLATFORM =~ /darwin/
 
 $CPPFLAGS += " -Wall" unless $CPPFLAGS.split.include? "-Wall"
+$CPPFLAGS += " -g" unless $CPPFLAGS.split.include? "-g"
+$CPPFLAGS += " -rdynamic" unless $CPPFLAGS.split.include? "-rdynamic"
 
 CONFIG['LDSHARED'] = '$(CXX) -shared' unless RUBY_PLATFORM =~ /darwin/
 

ext/v8/upstream/Makefile

@@ -3,14 +3,21 @@ SCONS=build/scons/install/bin/scons
 SCONSSRC=build/scons
 V8SRC=build/v8
 LIBV8=build/v8/libv8.a
+LIBV8_G=build/v8/libv8_g.a
 GCC_VERSION=$(shell ruby -e 'puts %x{gcc --version} =~ /(\d)\.(\d)\.\d/ ? $$1 + $$2 : "UNKNOWN"')
 ARCH=$(shell ruby -e "puts ['foo'].pack('p').size == 8 ? 'x64' : 'ia32'")
 
 all: $(LIBV8)
 
+debug: $(LIBV8_G)
+	cp $(LIBV8_G) $(LIBV8)
+
 $(LIBV8): $(SCONS) $(V8SRC)
 	cd build/v8 && GCC_VERSION=$(GCC_VERSION) ../scons/install/bin/scons arch=$(ARCH)
 
+$(LIBV8_G): $(SCONS) $(V8SRC)
+	cd build/v8 && GCC_VERSION=$(GCC_VERSION) ../scons/install/bin/scons arch=$(ARCH) mode=debug
+
 $(SCONS): $(SCONSSRC)
 	mkdir -p $(SCONSSRC)/install
 	python build/scons/setup.py install --prefix=install

ext/v8/v8.cpp

@@ -10,6 +10,7 @@
 #include "v8_try_catch.h"
 #include "v8_callbacks.h"
 #include "v8_external.h"
+#include "v8_exception.h"
 
 #include <stdio.h>
 
@@ -31,5 +32,6 @@ extern "C" {
         rr_init_v8_try_catch();
         rr_init_v8_callbacks();
         rr_init_v8_external();
+        rr_init_v8_exception();
     }
 }

ext/v8/v8_exception.cpp

@@ -0,0 +1,27 @@
+#include "v8_exception.h"
+#include "rr.h"
+#include "execinfo.h"
+#include "signal.h"
+
+namespace {
+
+  static void* stack[20];
+
+  void fatal(const char* location, const char* message) {
+    int size = backtrace(stack, 20);
+    backtrace_symbols_fd(stack, size, 2);
+    rb_raise(rb_eFatal, "%s: %s", location, message);    
+  }
+  void segfault(int sig) {
+    fprintf(stderr, "segfault: game over.\n");
+    void *elements[20];
+    int size = backtrace(stack, 20);
+    backtrace_symbols_fd(stack, size, 2);
+    exit(1);
+  }
+}
+
+void rr_init_v8_exception() {
+  v8::V8::SetFatalErrorHandler(fatal);
+  signal(SIGSEGV, segfault);
+}

ext/v8/v8_exception.h

@@ -0,0 +1,6 @@
+#ifndef _RR_V8_EXCEPTION_
+#define _RR_V8_EXCEPTION_
+
+void rr_init_v8_exception();
+
+#endif