spawnUri. Take two. This time I'll wait for Anton before committing :-).

runtime/lib/isolate.cc

Index: runtime/lib/isolate.cc
===================================================================
--- runtime/lib/isolate.cc	(revision 7916)
+++ runtime/lib/isolate.cc	(working copy)
@@ -239,30 +239,20 @@
 }
 
 
-static char* BuildIsolateName(const char* script_name,
-                              const char* class_name,
-                              const char* func_name) {
-  // Skip past any slashes in the script name.
-  const char* last_slash = strrchr(script_name, '/');
-  if (last_slash != NULL) {
-    script_name = last_slash + 1;
-  }
+static char* GetRootScriptUri(Isolate* isolate) {
+  const Library& library =
+      Library::Handle(isolate->object_store()->root_library());
+  ASSERT(!library.IsNull());
+  const String& script_name = String::Handle(library.url());
+  return isolate->current_zone()->MakeCopyOfString(script_name.ToCString());
+}
 
-  char* chars = NULL;
-  if (class_name && class_name[0] != '\0') {
-    const char* kFormat = "%s/%s.%s";
-    intptr_t len = OS::SNPrint(NULL, 0, kFormat, script_name, class_name,
-                               func_name) + 1;
-    chars = reinterpret_cast<char*>(
-        Isolate::Current()->current_zone()->Allocate(len));
-    OS::SNPrint(chars, len, kFormat, script_name, class_name, func_name);
-  } else {
-    const char* kFormat = "%s/%s";
-    intptr_t len = OS::SNPrint(NULL, 0, kFormat, script_name, func_name) + 1;
-    chars = reinterpret_cast<char*>(
-        Isolate::Current()->current_zone()->Allocate(len));
-    OS::SNPrint(chars, len, kFormat, script_name, func_name);
-  }
+
+static char* BuildMainName(const char* class_name) {
+  intptr_t len = OS::SNPrint(NULL, 0, "%s.main", class_name) + 1;
+  char* chars = reinterpret_cast<char*>(
+      Isolate::Current()->current_zone()->Allocate(len));
+  OS::SNPrint(chars, len, "%s.main", class_name);
   return chars;
 }
 
@@ -283,10 +273,11 @@
   void* callback_data = preserved_isolate->init_callback_data();
   char* error = NULL;
   Dart_IsolateCreateCallback callback = Isolate::CreateCallback();
-  const char* isolate_name = BuildIsolateName(library_url, class_name, "main");
+  const char* root_script_uri = GetRootScriptUri(preserved_isolate);
+  const char* main = BuildMainName(class_name);
   if (callback == NULL) {
     error = strdup("Null callback specified for isolate creation\n");
-  } else if (callback(isolate_name, callback_data, &error)) {
+  } else if (callback(root_script_uri, main, callback_data, &error)) {
     spawned_isolate = Isolate::Current();
     ASSERT(spawned_isolate != NULL);
     // Check arguments to see if the specified library and classes are
@@ -386,12 +377,51 @@
 }
 
 
+static bool CanonicalizeUri(Isolate* isolate,
+                            const Library& library,
+                            const String& uri,
+                            char** canonical_uri,
+                            char** error) {
+  Zone* zone = isolate->current_zone();
+  Dart_LibraryTagHandler handler = isolate->library_tag_handler();
+  if (handler == NULL) {
+    *error = zone->PrintToString(
+        "Unable to canonicalize uri '%s': no library tag handler found.",
+        uri.ToCString());
+    return false;
+  }
+  Dart_Handle result = handler(kCanonicalizeUrl,
+                               Api::NewHandle(isolate, library.raw()),
+                               Api::NewHandle(isolate, uri.raw()));
+  const Object& obj = Object::Handle(Api::UnwrapHandle(result));
+  if (obj.IsError()) {
+    Error& error_obj = Error::Handle();
+    error_obj ^= obj.raw();
+    *error = zone->PrintToString("Unable to canonicalize uri '%s': %s",
+                                 uri.ToCString(), error_obj.ToErrorCString());
+    return false;
+  } else if (obj.IsString()) {
+    String& string_obj = String::Handle();
+    string_obj ^= obj.raw();
+    *canonical_uri = zone->MakeCopyOfString(string_obj.ToCString());
+    return true;
+  } else {
+    *error = zone->PrintToString("Unable to canonicalize uri '%s': "
+                                 "library tag handler returned wrong type",
+                                 uri.ToCString());
+    return false;
+  }
+}
+
+
 class SpawnState {
  public:
   explicit SpawnState(const Function& func)
       : isolate_(NULL),
+        script_url_(NULL),
         library_url_(NULL),
         function_name_(NULL) {
+    script_url_ = strdup(GetRootScriptUri(Isolate::Current()));
     const Class& cls = Class::Handle(func.owner());
     ASSERT(cls.IsTopLevel());
     const Library& lib = Library::Handle(cls.library());
@@ -402,27 +432,54 @@
     function_name_ = strdup(func_name.ToCString());
   }
 
+  explicit SpawnState(const char* script_url)
+      : isolate_(NULL),
+        library_url_(NULL),
+        function_name_(NULL) {
+    script_url_ = strdup(script_url);
+    library_url_ = NULL;
+    function_name_ = strdup("main");
+  }
+
   ~SpawnState() {
+    free(script_url_);
     free(library_url_);
     free(function_name_);
   }
 
   Isolate* isolate() const { return isolate_; }
   void set_isolate(Isolate* value) { isolate_ = value; }
+  char* script_url() const { return script_url_; }
   char* library_url() const { return library_url_; }
   char* function_name() const { return function_name_; }
 
-  RawFunction* ResolveFunction() {
-    const String& lib_url =
-        String::Handle(String::NewSymbol(library_url()));
+  RawObject* ResolveFunction() {
+    // Resolve the library.
+    Library& lib = Library::Handle();
+    if (library_url()) {
+      const String& lib_url = String::Handle(String::New(library_url()));
+      lib = Library::LookupLibrary(lib_url);
+      if (lib.IsNull() || lib.IsError()) {
+        const String& msg = String::Handle(String::NewFormatted(
+            "Unable to find library '%s'.", library_url()));
+        return LanguageError::New(msg);
+      }
+    } else {
+      lib = isolate()->object_store()->root_library();
+    }
+    ASSERT(!lib.IsNull());
+
+    // Resolve the function.
     const String& func_name =
-        String::Handle(String::NewSymbol(function_name()));
-
-    const Library& lib = Library::Handle(Library::LookupLibrary(lib_url));
-    if (lib.IsNull() || lib.IsError()) {
-      return Function::null();
+        String::Handle(String::New(function_name()));
+    const Function& func = Function::Handle(lib.LookupLocalFunction(func_name));
+    if (func.IsNull()) {
+      const String& msg = String::Handle(String::NewFormatted(
+          "Unable to resolve function '%s' in library '%s'.",
+          function_name(), (library_url() ? library_url() : script_url())));
+      return LanguageError::New(msg);
     }
-    return lib.LookupLocalFunction(func_name);
+    return func.raw();
   }
 
   void Cleanup() {
@@ -432,6 +489,7 @@
 
  private:
   Isolate* isolate_;
+  char* script_url_;
   char* library_url_;
   char* function_name_;
 };
@@ -441,40 +499,45 @@
   Isolate* parent_isolate = Isolate::Current();
 
   Dart_IsolateCreateCallback callback = Isolate::CreateCallback();
-  ASSERT(callback);
-  const char* isolate_name = BuildIsolateName(state->library_url(),
-                                              "",
-                                              state->function_name());
+  ASSERT(callback != NULL);
   void* init_data = parent_isolate->init_callback_data();
-  bool retval = (callback)(isolate_name, init_data, error);
-  if (retval) {
-    Isolate* child_isolate = Isolate::Current();
-    ASSERT(child_isolate);
-    state->set_isolate(child_isolate);
+  bool retval = (callback)(state->script_url(),
+                           state->function_name(),
+                           init_data,
+                           error);
+  if (!retval) {
+    Isolate::SetCurrent(parent_isolate);
+    return false;
+  }
 
-    // Attempt to resolve the entry function now, so that we fail fast
-    // in the case that the embedder's isolate create callback is
-    // violating its contract.
-    //
-    // TODO(turnidge): Revisit this once we have an isolate death api.
-    {
-      Zone zone(child_isolate);
-      HandleScope handle_scope(child_isolate);
-      const Function& func = Function::Handle(state->ResolveFunction());
-      if (func.IsNull()) {
-        *error = strdup(zone.PrintToString(
-            "Internal error while starting isolate '%s': "
-            "unable to resolve entry function '%s'.",
-            child_isolate->name(), state->function_name()));
-        retval = false;
-      }
+  Isolate* child_isolate = Isolate::Current();
+  ASSERT(child_isolate);
+  state->set_isolate(child_isolate);
+
+  // Attempt to resolve the entry function now, so that we fail fast
+  // in the case that the function cannot be resolved.
+  //
+  // TODO(turnidge): Revisit this once we have an isolate death api.
+  bool resolve_error = false;
+  {
+    Zone zone(child_isolate);
+    HandleScope handle_scope(child_isolate);
+    const Object& result = Object::Handle(state->ResolveFunction());
+    if (result.IsError()) {
+      Error& errobj = Error::Handle();
+      errobj ^= result.raw();
+      *error = strdup(errobj.ToErrorCString());
+      resolve_error = true;
     }
   }
-  if (!retval) {
+  if (resolve_error) {
     Dart::ShutdownIsolate();
+    Isolate::SetCurrent(parent_isolate);
+    return false;
   }
+
   Isolate::SetCurrent(parent_isolate);
-  return retval;
+  return true;
 }
 
 
@@ -489,11 +552,16 @@
     ASSERT(ClassFinalizer::FinalizePendingClasses());
     Object& result = Object::Handle();
 
-    const Function& func = Function::Handle(state->ResolveFunction());
+    result = state->ResolveFunction();
     delete state;
     state = NULL;
-    ASSERT(!func.IsNull());
-
+    if (result.IsError()) {
+      StoreError(isolate, result);
+      return false;
+    }
+    ASSERT(result.IsFunction());
+    Function& func = Function::Handle(isolate);
+    func ^= result.raw();
     GrowableArray<const Object*> args(0);
     const Array& kNoArgNames = Array::Handle();
     result = DartEntry::InvokeStatic(func, args, kNoArgNames);
@@ -506,28 +574,13 @@
 }
 
 
-DEFINE_NATIVE_ENTRY(isolate_spawnFunction, 1) {
-  GET_NATIVE_ARGUMENT(Closure, closure, arguments->At(0));
-  const Function& func = Function::Handle(closure.function());
-  const Class& cls = Class::Handle(func.owner());
-  if (!func.IsClosureFunction() || !func.is_static() || !cls.IsTopLevel()) {
-    const String& msg = String::Handle(String::New(
-        "spawnFunction expects to be passed a closure to a top-level static "
-        "function"));
-    ThrowIllegalArgException(msg);
-  }
-
-#if defined(DEBUG)
-  const Context& ctx = Context::Handle(closure.context());
-  ASSERT(ctx.num_variables() == 0);
-#endif
-
+static void Spawn(NativeArguments* arguments, SpawnState* state) {
   // Create a new isolate.
   char* error = NULL;
-  SpawnState* state = new SpawnState(func);
   if (!CreateIsolate(state, &error)) {
     delete state;
     const String& msg = String::Handle(String::New(error));
+    free(error);
     ThrowIsolateSpawnException(msg);
   }
 
@@ -550,6 +603,45 @@
 }
 
 
+DEFINE_NATIVE_ENTRY(isolate_spawnFunction, 1) {
+  GET_NATIVE_ARGUMENT(Closure, closure, arguments->At(0));
+  const Function& func = Function::Handle(closure.function());
+  const Class& cls = Class::Handle(func.owner());
+  if (!func.IsClosureFunction() || !func.is_static() || !cls.IsTopLevel()) {
+    const String& msg = String::Handle(String::New(
+        "spawnFunction expects to be passed a closure to a top-level static "
+        "function"));
+    ThrowIllegalArgException(msg);
+  }
+
+#if defined(DEBUG)
+  const Context& ctx = Context::Handle(closure.context());
+  ASSERT(ctx.num_variables() == 0);
+#endif
+
+  Spawn(arguments, new SpawnState(func));
+}
+
+
+DEFINE_NATIVE_ENTRY(isolate_spawnUri, 1) {
+  GET_NATIVE_ARGUMENT(String, uri, arguments->At(0));
+
+  // Canonicalize the uri with respect to the current isolate.
+  char* error = NULL;
+  char* canonical_uri = NULL;
+  const Library& root_lib =
+      Library::Handle(arguments->isolate()->object_store()->root_library());
+  if (!CanonicalizeUri(arguments->isolate(), root_lib, uri,
+                       &canonical_uri, &error)) {
+    const String& msg = String::Handle(String::New(error));
+    free(error);
+    ThrowIsolateSpawnException(msg);
+  }
+
+  Spawn(arguments, new SpawnState(canonical_uri));
+}
+
+
 DEFINE_NATIVE_ENTRY(isolate_getPortInternal, 0) {
   const Object& port = Object::Handle(ReceivePortCreate(isolate->main_port()));
   if (port.IsError()) {