Commit 04cfe01f authored Apr 19, 2024 by Tom Mulcahy Committed by tomm Sep 19, 2024

usb: Use Get/SetByteArrayRegion in bulkTransfer

This change fixes https://issuetracker.google.com/issues/335003907

This change replaces
GetPrimitiveArrayCritical/ReleasePrimitiveArrayCritical with
GetByteArrayRegion/SetByteArrayRegion.

This change is needed because the critical API variants are not
appropriate for this context. See the JNI docs:

After calling GetPrimitiveArrayCritical, the native code should not run
for an extended period of time before it calls
ReleasePrimitiveArrayCritical.

In bulkTransfer, we call usb_device_bulk_transfer between
GetPrimitiveArrayCritical/ReleasePrimitiveArrayCritical.
usb_device_bulk_transfer is a blocking call so this can lead to GC
hangs.

Instead, we allocate a new buffer with malloc and then call
GetByteArrayRegion/SetByteArrayRegion before/after
usb_device_bulk_transfer, depending on the direction of the endpoint.

Test: I ran UsbTests. I also sent a "TEST UNIT READY" to a USB drive and
verified the response.

Change-Id: I5c82aac3fe99e1f11044f20091bf3a940bc8f6a7

parent 2e1a903f

core/jni/android_hardware_UsbDeviceConnection.cpp

+14 −7

Original line number	Diff line number	Diff line
		@@ -190,18 +190,25 @@ android_hardware_UsbDeviceConnection_bulk_request(JNIEnv *env, jobject thiz,
		return -1;
		}

		jbyte* bufferBytes = NULL;
		if (buffer) {
		bufferBytes = (jbyte*)env->GetPrimitiveArrayCritical(buffer, NULL);
		bool is_dir_in = (endpoint & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN;
		std::unique_ptr<jbyte[]> bufferBytes(new (std::nothrow) jbyte[length]);
		if (!bufferBytes) {
		jniThrowException(env, "java/lang/OutOfMemoryError", NULL);
		return -1;
		}

		jint result = usb_device_bulk_transfer(device, endpoint, bufferBytes + start, length, timeout);
		if (!is_dir_in && buffer) {
		env->GetByteArrayRegion(buffer, start, length, bufferBytes.get());
		}

		if (bufferBytes) {
		env->ReleasePrimitiveArrayCritical(buffer, bufferBytes, 0);
		jint bytes_transferred =
		usb_device_bulk_transfer(device, endpoint, bufferBytes.get(), length, timeout);

		if (bytes_transferred > 0 && is_dir_in) {
		env->SetByteArrayRegion(buffer, start, bytes_transferred, bufferBytes.get());
		}

		return result;
		return bytes_transferred;
		}

		static jobject