Error checking for Stdio calls

runtime/bin/stdio.cc

Index: runtime/bin/stdio.cc
diff --git a/runtime/bin/stdio.cc b/runtime/bin/stdio.cc
index 47bd55478ee8f7fbf913abfc7e4daaa20d50be29..aa1c7c2288c52709efa432481f3bd31c5bea08cf 100644
--- a/runtime/bin/stdio.cc
+++ b/runtime/bin/stdio.cc
@@ -20,29 +20,52 @@ namespace bin {
 
 void FUNCTION_NAME(Stdin_ReadByte)(Dart_NativeArguments args) {
   ScopedBlockingCall blocker;
-  Dart_SetReturnValue(args, Dart_NewInteger(Stdin::ReadByte()));
+  int byte = -1;
+  if (Stdin::ReadByte(&byte)) {
+    Dart_SetReturnValue(args, Dart_NewInteger(byte));
+  } else {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  }
 }
 
 
 void FUNCTION_NAME(Stdin_GetEchoMode)(Dart_NativeArguments args) {
-  Dart_SetReturnValue(args, Dart_NewBoolean(Stdin::GetEchoMode()));
+  bool enabled = false;
+  if (Stdin::GetEchoMode(&enabled)) {
+    Dart_SetReturnValue(args, Dart_NewBoolean(enabled));
+  } else {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  }
 }
 
 
 void FUNCTION_NAME(Stdin_SetEchoMode)(Dart_NativeArguments args) {
   bool enabled = DartUtils::GetBooleanValue(Dart_GetNativeArgument(args, 0));
-  Stdin::SetEchoMode(enabled);
+  if (Stdin::SetEchoMode(enabled)) {
+    Dart_SetReturnValue(args, Dart_True());
+  } else {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  }
 }
 
 
 void FUNCTION_NAME(Stdin_GetLineMode)(Dart_NativeArguments args) {
-  Dart_SetReturnValue(args, Dart_NewBoolean(Stdin::GetLineMode()));
+  bool enabled = false;
+  if (Stdin::GetLineMode(&enabled)) {
+    Dart_SetReturnValue(args, Dart_NewBoolean(enabled));
+  } else {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  }
 }
 
 
 void FUNCTION_NAME(Stdin_SetLineMode)(Dart_NativeArguments args) {
   bool enabled = DartUtils::GetBooleanValue(Dart_GetNativeArgument(args, 0));
-  Stdin::SetLineMode(enabled);
+  if (Stdin::SetLineMode(enabled)) {
+    Dart_SetReturnValue(args, Dart_True());
+  } else {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  }
 }