Calling function from shared library in V8 7.7.299.11

[Darin Dimitrov]

I am cross compiling V8 for android and I have created a shared library containing a simple function which adds some property to a provided object:

extern "C" void MyFunc(Isolate* isolate, Local<Object>& obj) {
    Local<Context> context = isolate->GetCurrentContext();
    obj->Set(context, v8::String::NewFromUtf8(isolate, "someProp").ToLocalChecked(), Number::New(isolate, 500));
}

My goal  purpose is to call this function from my android application in which I have embedded V8:

typedef void (*MyCallback)(Isolate* isolate, Local<Object>& obj);

void* handle = dlopen("/data/data/com.tns.testapplication/files/app/modules/libCalc-x86_64.so", RTLD_LAZY);

MyCallback func = reinterpret_cast<MyCallback>(dlsym(handle, "MyFunc"));
Local<Object> exportsObj = Object::New(isolate);
func(isolate, exportsObj);

This successfully invokes "MyFunc" from the shared library and sets the "someProp" property on the passed object. 

Starting from V8 7.7.299.11 calling obj->Set() inside the library crashes with SIGSEGV and without any stacktrace.

I have noticed that if I set the property before calling the function then it works:

exportsObj->Set(context, v8::String::NewFromUtf8(isolate, "someProp").ToLocalChecked(), v8::Null(isolate));
func(isolate, exportsObj);

Any idea what might have changed between the official V8 7.6 and 7.7 releases that might explain this behaviour or any tips that would allow me to debug this further?

[Jakob Gruber]

Could this be another libcxx mismatch issue and 7.7 just exposes it incidentally?

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[Darin Dimitrov]

It might be, but normally I build my .so with the exact same custom libc++ which I use to build my android app. I am also able to perform other operations on the object such as ->Get

On Thursday, September 12, 2019 at 4:16:00 PM UTC+3, Jakob Gruber wrote:

Could this be another libcxx mismatch issue and 7.7 just exposes it incidentally?

On Thu, Sep 12, 2019 at 2:54 PM Darin Dimitrov <darin....@gmail.com> wrote:

I am cross compiling V8 for android and I have created a shared library containing a simple function which adds some property to a provided object:

extern "C" void MyFunc(Isolate* isolate, Local<Object>& obj) {
    Local<Context> context = isolate->GetCurrentContext();
    obj->Set(context, v8::String::NewFromUtf8(isolate, "someProp").ToLocalChecked(), Number::New(isolate, 500));
}

My goal  purpose is to call this function from my android application in which I have embedded V8:

typedef void (*MyCallback)(Isolate* isolate, Local<Object>& obj);

void* handle = dlopen("/data/data/com.tns.testapplication/files/app/modules/libCalc-x86_64.so", RTLD_LAZY);

MyCallback func = reinterpret_cast<MyCallback>(dlsym(handle, "MyFunc"));
Local<Object> exportsObj = Object::New(isolate);
func(isolate, exportsObj);

This successfully invokes "MyFunc" from the shared library and sets the "someProp" property on the passed object. 

Starting from V8 7.7.299.11 calling obj->Set() inside the library crashes with SIGSEGV and without any stacktrace.

I have noticed that if I set the property before calling the function then it works:

exportsObj->Set(context, v8::String::NewFromUtf8(isolate, "someProp").ToLocalChecked(), v8::Null(isolate));
func(isolate, exportsObj);

Any idea what might have changed between the official V8 7.6 and 7.7 releases that might explain this behaviour or any tips that would allow me to debug this further?

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