Support length operation without opening file.

runtime/bin/file.cc

 // Copyright (c) 2012, 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 "bin/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
@@ skipping 333 matching lines @@
       if (Dart_IsError(err)) {
         Dart_PropagateError(err);
       }
       Dart_SetReturnValue(args, err);
     }
   }
   Dart_ExitScope();
 }
 
 
+void FUNCTION_NAME(File_LengthFromName)(Dart_NativeArguments args) {
+  Dart_EnterScope();
+  const char* name =
+      DartUtils::GetStringValue(Dart_GetNativeArgument(args, 0));
+  intptr_t return_value = File::LengthFromName(name);
+  if (return_value >= 0) {
+    Dart_SetReturnValue(args, Dart_NewInteger(return_value));
+  } else {
+    Dart_Handle err = DartUtils::NewDartOSError();
+    if (Dart_IsError(err)) {
+      Dart_PropagateError(err);
+    }
+    Dart_SetReturnValue(args, err);
+  }
+  Dart_ExitScope();
+}
+
+
 void FUNCTION_NAME(File_Flush)(Dart_NativeArguments args) {
   Dart_EnterScope();
   intptr_t value =
       DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 0));
   File* file = reinterpret_cast<File*>(value);
   if (file != NULL) {
     if (file->Flush()) {
       Dart_SetReturnValue(args, Dart_True());
     } else {
       Dart_Handle err = DartUtils::NewDartOSError();
@@ skipping 296 matching lines @@
         return CObject::NewOSError();
       }
     } else {
       return CObject::FileClosedError();
     }
   }
   return CObject::IllegalArgumentError();
 }
 
 
+static CObject* FileLengthFromNameRequest(const CObjectArray& request) {
+  if (request.Length() == 2 && request[1]->IsString()) {
+    CObjectString filename(request[1]);
+    intptr_t return_value = File::LengthFromName(filename.CString());
+    if (return_value >= 0) {
+      return new CObjectIntptr(CObject::NewIntptr(return_value));
+    } else {
+      return CObject::NewOSError();
+    }
+  }
+  return CObject::IllegalArgumentError();
+}
+
+
 static CObject* FileFlushRequest(const CObjectArray& request) {
   intptr_t return_value = -1;
   if (request.Length() == 2 && request[1]->IsIntptr()) {
     File* file = CObjectToFilePointer(request[1]);
     if (file != NULL && !file->IsClosed()) {
       if (file->Flush()) {
         return CObject::True();
       } else {
         return CObject::NewOSError();
       }
@@ skipping 177 matching lines @@
           break;
         case File::kSetPositionRequest:
           response = FileSetPositionRequest(request);
           break;
         case File::kTruncateRequest:
           response = FileTruncateRequest(request);
           break;
         case File::kLengthRequest:
           response = FileLengthRequest(request);
           break;
+        case File::kLengthFromNameRequest:
+          response = FileLengthFromNameRequest(request);
+          break;
         case File::kFlushRequest:
           response = FileFlushRequest(request);
           break;
         case File::kReadByteRequest:
           response = FileReadByteRequest(request);
           break;
         case File::kWriteByteRequest:
           response = FileWriteByteRequest(request);
           break;
         case File::kReadListRequest:
@@ skipping 44 matching lines @@
   Dart_EnterScope();
   Dart_SetReturnValue(args, Dart_Null());
   Dart_Port service_port = File::GetServicePort();
   if (service_port != kIllegalPort) {
     // Return a send port for the service port.
     Dart_Handle send_port = Dart_NewSendPort(service_port);
     Dart_SetReturnValue(args, send_port);
   }
   Dart_ExitScope();
 }