use JNI_GetCreatedJavaVMs

Author: damlayildiz

src/call_java.c

@@ -7,15 +7,33 @@
 
 JavaVM* gJvm = NULL;
 
-JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
-    gJvm = vm;
-    return JNI_VERSION_1_6;
+void findJvm() {
+    if (gJvm != NULL) {
+        return;
+    }
+
+    JavaVM* vmBuf[1];
+    jsize nVMs = 0;
+
+    jint res = JNI_GetCreatedJavaVMs(vmBuf, 1, &nVMs);
+    if (res == JNI_OK && nVMs > 0) {
+        gJvm = vmBuf[0];
+    } else {
+        gJvm = NULL;
+    }
 }
 
 JNIEnv* getEnv() {
+    findJvm();
+    if (gJvm == NULL) {
+        printf("Could not find JavaVM\n");
+        return NULL;
+    }
+
     JNIEnv* env;
     if ((*gJvm)->GetEnv(gJvm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
         if ((*gJvm)->AttachCurrentThread(gJvm, (void**)&env, NULL) != 0) {
+            printf("Failed to attach current thread\n");
             return NULL;
         }
     }
@@ -24,34 +42,18 @@ JNIEnv* getEnv() {
 
 const char* call_https_java(JNIEnv* env) {
     jclass cls = (*env)->FindClass(env, "HttpsCaller");
-    if ((*env)->ExceptionCheck(env)) {
-        (*env)->ExceptionDescribe(env);
-        (*env)->ExceptionClear(env);
-        return "Class not found (exception)";
-    }
-    if (!cls) return "Class not found";
 
     jmethodID mid = (*env)->GetStaticMethodID(env, cls, "callHttps", "()Ljava/lang/String;");
-    if ((*env)->ExceptionCheck(env)) {
-        (*env)->ExceptionDescribe(env);
-        (*env)->ExceptionClear(env);
-        return "Method not found (exception)";
-    }
-    if (!mid) return "Method not found";
 
     jstring result = (jstring)(*env)->CallStaticObjectMethod(env, cls, mid);
-    if ((*env)->ExceptionCheck(env)) {
-        (*env)->ExceptionDescribe(env);
-        (*env)->ExceptionClear(env);
-        return "Java method threw exception";
-    }
-    if (!result) return "Java method returned null";
 
-    const char* str = (*env)->GetStringUTFChars(env, result, 0);
-    if (!str) return "Failed to get UTF chars";
+    const char* str = (*env)->GetStringUTFChars(env, result, NULL);
 
     char* copied = strdup(str);
+
     (*env)->ReleaseStringUTFChars(env, result, str);
+    (*env)->DeleteLocalRef(env, result);
+    (*env)->DeleteLocalRef(env, cls);
 
-    return copied ? copied : "Memory allocation failed";
+    return copied;
 }

test/unit.c

@@ -3285,12 +3285,6 @@ bool test_call_https_java(void) {
     const char* javaResult = call_https_java(env);
     if (javaResult) {
         printf("Got from Java: %s\n", javaResult);
-        if (strcmp(javaResult, "Memory allocation failed") != 0 &&
-            strcmp(javaResult, "Class not found") != 0 &&
-            strcmp(javaResult, "Method not found") != 0 &&
-            strstr(javaResult, "exception") == NULL) {
-            free((void*)javaResult);
-        }
         return true;
     } else {
         printf("call_https_java returned NULL\n");