From b058dcf64e08db11dbd8d83b561d27a040eff74a Mon Sep 17 00:00:00 2001
From: Peter Johnson <johnson.peter@gmail.com>
Date: Fri, 22 Nov 2019 08:12:17 -0800
Subject: [PATCH] Catch exceptions generated by OpenCV in cscore JNI (#2118)

---
 cscore/build.gradle                           |  3 +-
 .../main/native/cpp/jni/CameraServerJNI.cpp   | 81 +++++++++++++++----
 2 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/cscore/build.gradle b/cscore/build.gradle
index 4514b95f9a..9b84031534 100644
--- a/cscore/build.gradle
+++ b/cscore/build.gradle
@@ -19,7 +19,8 @@ ext {
     sharedCvConfigs = [cscore    : [],
                        cscoreBase: [],
                        cscoreDev : [],
-                       cscoreTest: []]
+                       cscoreTest: [],
+                       cscoreJNIShared: []]
     staticCvConfigs = [cscoreJNI: []]
     useJava = true
     useCpp = true
diff --git a/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp b/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
index c50a7dbd37..52a0fea718 100644
--- a/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
+++ b/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
@@ -5,6 +5,9 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
+#include <exception>
+
+#include <opencv2/core/core.hpp>
 #include <wpi/SmallString.h>
 #include <wpi/jni_util.h>
 #include <wpi/raw_ostream.h>
@@ -33,6 +36,7 @@ static JClass rawFrameCls;
 static JException videoEx;
 static JException nullPointerEx;
 static JException unsupportedEx;
+static JException exceptionEx;
 // Thread-attached environment for listener callbacks.
 static JNIEnv* listenerEnv = nullptr;
 
@@ -45,7 +49,8 @@ static const JClassInit classes[] = {
 static const JExceptionInit exceptions[] = {
     {"edu/wpi/cscore/VideoException", &videoEx},
     {"java/lang/NullPointerException", &nullPointerEx},
-    {"java/lang/UnsupportedOperationException", &unsupportedEx}};
+    {"java/lang/UnsupportedOperationException", &unsupportedEx},
+    {"java/lang/Exception", &exceptionEx}};
 
 static void ListenerOnStart() {
   if (!jvm) return;
@@ -67,6 +72,30 @@ static void ListenerOnExit() {
   jvm->DetachCurrentThread();
 }
 
+/// throw java exception
+static void ThrowJavaException(JNIEnv* env, const std::exception* e) {
+  wpi::SmallString<128> what;
+  jclass je = 0;
+
+  if (e) {
+    const char* exception_type = "std::exception";
+
+    if (dynamic_cast<const cv::Exception*>(e)) {
+      exception_type = "cv::Exception";
+      je = env->FindClass("org/opencv/core/CvException");
+    }
+
+    what = exception_type;
+    what += ": ";
+    what += e->what();
+  } else {
+    what = "unknown exception";
+  }
+
+  if (!je) je = exceptionEx;
+  env->ThrowNew(je, what.c_str());
+}
+
 extern "C" {
 
 JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved) {
@@ -1096,10 +1125,16 @@ JNIEXPORT void JNICALL
 Java_edu_wpi_cscore_CameraServerCvJNI_putSourceFrame
   (JNIEnv* env, jclass, jint source, jlong imageNativeObj)
 {
-  cv::Mat& image = *((cv::Mat*)imageNativeObj);
-  CS_Status status = 0;
-  cs::PutSourceFrame(source, image, &status);
-  CheckStatus(env, status);
+  try {
+    cv::Mat& image = *((cv::Mat*)imageNativeObj);
+    CS_Status status = 0;
+    cs::PutSourceFrame(source, image, &status);
+    CheckStatus(env, status);
+  } catch (const std::exception& e) {
+    ThrowJavaException(env, &e);
+  } catch (...) {
+    ThrowJavaException(env, 0);
+  }
 }
 
 // int width, int height, int pixelFormat, int totalData
@@ -1555,11 +1590,19 @@ JNIEXPORT jlong JNICALL
 Java_edu_wpi_cscore_CameraServerCvJNI_grabSinkFrame
   (JNIEnv* env, jclass, jint sink, jlong imageNativeObj)
 {
-  cv::Mat& image = *((cv::Mat*)imageNativeObj);
-  CS_Status status = 0;
-  auto rv = cs::GrabSinkFrame(sink, image, &status);
-  CheckStatus(env, status);
-  return rv;
+  try {
+    cv::Mat& image = *((cv::Mat*)imageNativeObj);
+    CS_Status status = 0;
+    auto rv = cs::GrabSinkFrame(sink, image, &status);
+    CheckStatus(env, status);
+    return rv;
+  } catch (const std::exception& e) {
+    ThrowJavaException(env, &e);
+    return 0;
+  } catch (...) {
+    ThrowJavaException(env, 0);
+    return 0;
+  }
 }
 
 /*
@@ -1571,11 +1614,19 @@ JNIEXPORT jlong JNICALL
 Java_edu_wpi_cscore_CameraServerCvJNI_grabSinkFrameTimeout
   (JNIEnv* env, jclass, jint sink, jlong imageNativeObj, jdouble timeout)
 {
-  cv::Mat& image = *((cv::Mat*)imageNativeObj);
-  CS_Status status = 0;
-  auto rv = cs::GrabSinkFrameTimeout(sink, image, timeout, &status);
-  CheckStatus(env, status);
-  return rv;
+  try {
+    cv::Mat& image = *((cv::Mat*)imageNativeObj);
+    CS_Status status = 0;
+    auto rv = cs::GrabSinkFrameTimeout(sink, image, timeout, &status);
+    CheckStatus(env, status);
+    return rv;
+  } catch (const std::exception& e) {
+    ThrowJavaException(env, &e);
+    return 0;
+  } catch (...) {
+    ThrowJavaException(env, 0);
+    return 0;
+  }
 }
 
 static void SetRawFrameData(JNIEnv* env, jobject rawFrameObj,