Rework error handling in the service protocol and in Observatory.

runtime/vm/json_stream.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/json_stream.h"
 #include "vm/message.h"
@@ skipping 61 matching lines @@
   buffer_.Printf("{\"result\":");
 }
 
 
 void JSONStream::SetupError() {
   buffer_.Clear();
   buffer_.Printf("{\"error\":");
 }
 
 
+static const char* GetJSONRpcErrorMessage(intptr_t code) {
+  switch (code) {
+    case kParseError:
+      return "Parse error";
+    case kInvalidRequest:
+      return "Invalid Request";
+    case kMethodNotFound:
+      return "Method not found";
+    case kInvalidParams:
+      return "Invalid params";
+    case kInternalError:
+      return "Internal error";
+    case kVMMustBePaused:
+      return "VM must be paused";
+    case kNoBreakAtLine:
+      return "Cannot set breakpoint at line";
+    case kNoBreakAtFunction:
+      return "Cannot set breakpoint at function";
+    case kProfilingDisabled:
+      return "Profiling is disabled";
+    default:
+      UNIMPLEMENTED();
+      return "Unexpected rpc error code";
+  }
+}
+
+
+static void PrintRequest(JSONObject* obj, JSONStream* js) {
+  JSONObject jsobj(obj, "request");
+  jsobj.AddProperty("method", js->method());
+  {
+    JSONObject params(&jsobj, "params");
+    for (intptr_t i = 0; i < js->num_params(); i++) {
+      params.AddProperty(js->GetParamKey(i), js->GetParamValue(i));
+    }
+  }
+}
+
+
+void JSONStream::PrintError(intptr_t code,
+                            const char* details_format, ...) {
+  SetupError();
+  JSONObject jsobj(this);
+  jsobj.AddProperty("code", code);
+  jsobj.AddProperty("message", GetJSONRpcErrorMessage(code));
+  {
+    JSONObject data(&jsobj, "data");
+    PrintRequest(&data, this);
+    if (details_format != NULL) {
+      Isolate* isolate = Isolate::Current();
+
+      va_list args;
+      va_start(args, details_format);
+      intptr_t len = OS::VSNPrint(NULL, 0, details_format, args);
+      va_end(args);
+
+      char* buffer = isolate->current_zone()->Alloc<char>(len + 1);

[Cutch, 2015/05/13 17:50:10]

zone->PrintToString ?

[turnidge, 2015/05/14 17:53:43]

We would need to add a new version of zone->PrintToString that took va_list --
zone->VPrintToString or something.

+      va_list args2;
+      va_start(args2, details_format);
+      OS::VSNPrint(buffer, (len + 1), details_format, args2);
+      va_end(args2);
+
+      data.AddProperty("details", buffer);
+    }
+  }
+}
+
+
 static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
   void* new_ptr = realloc(reinterpret_cast<void*>(ptr), new_size);
   return reinterpret_cast<uint8_t*>(new_ptr);
 }
 
 
 void JSONStream::PostReply() {
   Dart_Port port = reply_port();
   ASSERT(port != ILLEGAL_PORT);
   set_reply_port(ILLEGAL_PORT);  // Prevent double replies.
@@ skipping 418 matching lines @@
   intptr_t len2 = OS::VSNPrint(p, len+1, format, args);
   va_end(args);
   ASSERT(len == len2);
   stream_->buffer_.AddChar('"');
   stream_->AddEscapedUTF8String(p);
   stream_->buffer_.AddChar('"');
   free(p);
 }
 
 }  // namespace dart