JNI - Send a large byte[] buffer to C++

Question

I'm trying to send a large java buffer byte[] (e.g. 460800) to C++ function using JNI. Below is the sample code:

JNIExport void JNICALL XXXXXX_onRecvData(JNIEnv *env, jclass class, jbyteArray data) {
  jbyte *pData = NULL;
  pData = env->GetByteArrayElements(data, NULL);
  // call some function here
  Method((UINT8 *) pData, (UINT16)(env->GetArrayLength(data));
  env->ReleaseByteArrayElements(data, pData, 0);
}

Where

Method(uint8_t* buf, uint32_t buf_size) {
  // print buf_size
}

When I print buf_size, I get some small value e.g.2048. It means I'm not receiving full buffer in JNI function. Is there any restriction on the size of buffer that I can send using JNI? Any idea why it might be happening?

Answer 1

You're casting your array length to a UINT16. Any size larger than 65,535 bytes is going to cause you trouble.

460800 % 65536 is, not surprisingly, 2048.