Add an API function to get a debugger stack trace from an error handle.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 74117cc890c7626dfab5cecd7e978bde797cb284..53a650da1c86c2b1104cea09578c84dae59b14da 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -15,6 +15,7 @@
 #include "vm/dart_api_message.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
+#include "vm/debugger.h"
 #include "vm/debuginfo.h"
 #include "vm/exceptions.h"
 #include "vm/flags.h"
@@ -375,19 +376,95 @@ DART_EXPORT Dart_Handle Dart_ErrorGetException(Dart_Handle handle) {
 }
 
 
-DART_EXPORT Dart_Handle Dart_ErrorGetStacktrace(Dart_Handle handle) {
+DART_EXPORT Dart_Handle Dart_ErrorGetStacktrace(
+    Dart_Handle handle,
+    Dart_ExceptionStackTrace *trace) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   const Object& obj = Object::Handle(isolate, Api::UnwrapHandle(handle));
   if (obj.IsUnhandledException()) {
     const UnhandledException& error = UnhandledException::Cast(obj);
-    return Api::NewHandle(isolate, error.stacktrace());
+    Stacktrace& dart_stacktrace = Stacktrace::Handle(isolate);
+    dart_stacktrace ^= error.stacktrace();
+    if (dart_stacktrace.IsNull()) {
+      *trace = NULL;
+    } else {
+      ExceptionStackTrace* cpp_stacktrace =
+          dart_stacktrace.BuildExceptionStackTrace();
+      *trace = reinterpret_cast<Dart_ExceptionStackTrace>(cpp_stacktrace);
+    }
+    return Api::Success();
   } else if (obj.IsError()) {
     return Api::NewError("This error is not an unhandled exception error.");
   } else {
     return Api::NewError("Can only get stacktraces from error handles.");
   }
 }
+DART_EXPORT Dart_Handle Dart_CurrentStacktrace(
+    Dart_ExceptionStackTrace *trace) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  ExceptionStackTrace* cpp_stacktrace =
+      isolate->debugger()->BuildExceptionStackTrace();
+  *trace = reinterpret_cast<Dart_ExceptionStackTrace>(cpp_stacktrace);
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_StacktraceLength(Dart_ExceptionStackTrace trace,
+                                              intptr_t* length) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  if (trace == NULL) {
+    return Api::NewError("%s expects argument 'trace' to be non-null.",
+                         CURRENT_FUNC);
+  }
+  ExceptionStackTrace *stack_trace =
+      reinterpret_cast<ExceptionStackTrace*>(trace);
+  if (length == NULL) {
+    return Api::NewError("%s expects argument 'length' to be non-null.",
+                         CURRENT_FUNC);
+  }
+  *length = stack_trace->Length();
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_StacktraceFrameInfo(
+                            Dart_ExceptionStackTrace trace,
+                            intptr_t frame_index,
+                            Dart_Handle* function_name,
+                            Dart_Handle* script_url,
+                            intptr_t* line_number,
+                            intptr_t* col_number) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  if (trace == NULL) {
+    return Api::NewError("%s expects argument 'trace' to be non-null.",
+                         CURRENT_FUNC);
+  }
+  ExceptionStackTrace *stack_trace =
+      reinterpret_cast<ExceptionStackTrace*>(trace);
+  if (frame_index < 0 || frame_index >= stack_trace->Length()) {
+    return Api::NewError(
+        "%s: frame index was out of bounds (%" Pd ")",
+        CURRENT_FUNC, frame_index);
+  }
+  ExceptionStackFrame *frame = stack_trace->FrameAt(frame_index);
+  if (function_name != NULL) {
+    *function_name = Api::NewHandle(isolate, frame->function_name());
+  }
+  if (script_url != NULL) {
+    *script_url = Api::NewHandle(isolate, frame->script_uri());
+  }
+  if (line_number != NULL) {
+    *line_number = frame->line_number();
+  }
+  if (col_number != NULL) {
+    *col_number = frame->column_number();
+  }
+  return Api::Success();
+}
 
 
 // TODO(turnidge): This clones Api::NewError.  I need to use va_copy to