XMLHttpRequest broken in Dartium

[DartBot]

This issue was originally filed by sammcca...@google.com

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In latest build (dartium-lucid64-inc-8445.8445)

Internal error: '/mnt/data/b/build/slave/dartium-lucid64-inc/build/src/out/Release/obj/gen/webkit/bindings/dart/dart/XMLHttpRequestImplementation.dart': Error: line 6 pos 894: native function 'XMLHttpRequest_setRequestHeader_Callback' cannot be found
_addEventListener_1@33cc944a ( type , listener ) ; return ; } _addEventListener_2@33cc944a ( type , listener , useCapture ) ; } void _addEventListener_1@33cc944a ( type , listener ) native XMLHttpRequest_addEventListener_1_Callback ; void _addEventListener_2@33cc944a ( type , /samples/schedule/schedule.dart:1

Build dartium-lucid64-inc-8053.8053 worked fine.

[DartBot]

This comment was originally written by antonm@google.com

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Sam,

may you provide more details?

Do you create XMLHttpRequest in DOM-enabled isolate?

Full snippet is really appreciated.

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Added Area-Dartium, NeedsInfo labels.

[DartBot]

This comment was originally written by sammcca...@google.com

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Apologies for the lack of detail, I assumed the resolver failure meant it was completely broken.

I'm not creating any isolates.

The full program is complex and includes obfuscated javascript not under my control, I can send it to you internally if that helps.

It's not easy for me to identify what part is failing, as Dartium doesn't provide a stack trace, and simply points at line 1 of my source file.

I can try to cut it down to a simple example by trial and error.

[DartBot]

This comment was originally written by antonm@google.com

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Sam,

do you run Dart natively or compile it to JS first?

[DartBot]

This comment was originally written by sammcca...@google.com

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This is natively.
When compiled to JS I use regular chrome, and it works (well, there are different bugs :-)

[DartBot]

This comment was originally written by antonm@google.com

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I see, thanks. If you can give me a pointer to the app, even messy one, I should be able to debug it.

[DartBot]

This comment was originally written by antonm@google.com

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That looks like DartVM bug, but please, reassign, if I am wrong.

Assigning to Siva for further dispatches.

In my case native resolver is invoked for instance method declared as:

void setRequestHeader(String header, String value) native "XMLHttpRequest_setRequestHeader_Callback";

with argument count 2 and here Dartium fails to dispatch as it expects 3 args method (this and two remaining args.)

How to debug (on Linux):

1. Build Debug version of Dartium (x64 should work as well);
2. Start Dartium with a request to attach gdb to each renderer process:

./out/Debug/chrome --disable-hang-monitor --disable-seccomp-sandbox --renderer-cmd-prefix="xterm -e gdb --args" --user-data-dir http://tunafish.muc.corp.google.com/samples/schedule/

3. when gdb shows up, put a break point at the very end of generated XMLHttpReqest dispatcher (file is out/Debug/obj/gen/webkit/bindings/dart/cpp/DartXMLHttpRequest.cpp, and gdb should be able to find it as just DartXMLHttpRequest.cpp), the dispatcher is at the very end and bailout for failed search is currently at line 602.

4. run Dartium and watch for strings which come to this resolver, the following works for me in gdb to print WebCore strings:

 p (*name.ascii().m_buffer.m_ptr).m_vector.m_buffer

5. after a couple of hits, you should see that "XMLHttpRequest_setRequestHeader_Callback" comes with argumentCount == 2.

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Set owner to @a-siva.
Removed Area-Dartium label.
Added Area-VM, Accepted labels.

[DartBot]

This comment was originally written by antonm@google.com

[a-siva]

We seem to be creating an implicit closure function of setRequestHeader somewhere. Since we don't count 'this' in the number of parameters for an implicit closure function (it is a captured variable in the context) we end up with argument count being 2 when we come down to resolve the native function.

A simple test below demonstrates the issue:

void MyNativeClosure(Dart_NativeArguments args) {
  Dart_EnterScope();
  int i = Dart_GetNativeArgumentCount(args);
  Dart_SetReturnValue(args, Dart_NewInteger(i));
  Dart_ExitScope();
}

static Dart_NativeFunction MyNativeClosureResolver(Dart_Handle name,
                                                   int arg_count) {
  if (arg_count == 2) {
    return &MyNativeClosure;
  } else {
    UNREACHABLE();
    return NULL;
  }
}

TEST_CASE(NativeFunctionClosure) {
  const char* kScriptChars =
      "class Test {"
      " int foo(int i) native "SomeNativeClosure";"
      " int bar(int i) { var func = foo; func(i); }"
      "}"
      "int testMain() {"
      " Test obj = new Test();"
      " return obj.foo(1) + obj.bar(1);"
      "}";

  Dart_Handle result;

  // Load a test script.
  Dart_Handle url = Dart_NewString(TestCase::url());
  Dart_Handle source = Dart_NewString(kScriptChars);
  result = Dart_SetLibraryTagHandler(library_handler);
  EXPECT_VALID(result);
  Dart_Handle lib = Dart_LoadScript(url, source);
  EXPECT_VALID(lib);
  EXPECT(Dart_IsLibrary(lib));
  result = Dart_SetNativeResolver(lib, &MyNativeClosureResolver);
  EXPECT_VALID(result);

  result = Dart_Invoke(lib, Dart_NewString("testMain"), 0, NULL);
  EXPECT_VALID(result);
  EXPECT(Dart_IsInteger(result));
  int64_t value = 0;
  EXPECT_VALID(Dart_IntegerToInt64(result, &value));
  EXPECT_EQ(2, value);
}

The spec is not clear on whether it is legal to create an implicit closure of a native function, we should probably not allow that.

[a-siva]

Added this to the M1 milestone.

[a-siva]

 https://chromiumcodereview.appspot.com//10535180
 https://chromiumcodereview.appspot.com//10572029

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Added Fixed label.