From a174f452fc48735da7ee49ab5c906528f87b77b5 Mon Sep 17 00:00:00 2001

From: Jakub Filak <jfilak@redhat.com>

Date: Thu, 9 Jan 2014 22:56:28 +0100

Subject: [PATCH 26/39] Surround all JNI calls in try catch all block

Related to rhbz#1051198

---

 src/abrt-checker.c            | 273 ++++++++++++++++++------------------------

 src/jthrowable_circular_buf.c |  40 ++++++-

 2 files changed, 155 insertions(+), 158 deletions(-)

diff --git a/src/abrt-checker.c b/src/abrt-checker.c

index fb0c0eb..b6f11e8 100644

--- a/src/abrt-checker.c

+++ b/src/abrt-checker.c

@@ -631,6 +631,26 @@ static void report_stacktrace(

 /*

+ * Returns logical true if exception occurred and clears it.

+ */

+static inline int check_and_clear_exception(

+        JNIEnv     *jni_env)

+{

+        if ((*jni_env)->ExceptionOccurred(jni_env))

+        {

+#ifdef VERBOSE

+            (*jni_env)->ExceptionDescribe(jni_env);

+#endif

+            (*jni_env)->ExceptionClear(jni_env);

+            return 1;

+        }

+

+        return 0;

+}

+

+

+

+/*

  * Print a message when any JVM TI error occurs.

  */

 static void print_jvmti_error(

@@ -666,12 +686,13 @@ static int get_tid(

     }

     jmethodID get_id = (*jni_env)->GetMethodID(jni_env, thread_class, "getId", "()J" );

-    if (NULL == get_id)

+    if (check_and_clear_exception(jni_env) || NULL == get_id)

     {

-        VERBOSE_PRINT("Cannot method java.lang.Thread.getId()J\n");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of java/lang/Thread.getId()J\n");

         return 1;

     }

+    /* Thread.getId() throws nothing */

     *tid = (*jni_env)->CallLongMethod(jni_env, thr, get_id);

     return 0;

@@ -908,7 +929,6 @@ static void get_thread_name(

 }

-

 /*

  * Read executable name from link /proc/${PID}/exe

  */

@@ -1068,7 +1088,7 @@ static char *get_main_class(

     char *class_name;

     error_code = (*jvmti_env)->GetSystemProperty(jvmti_env, "sun.java.command", &class_name);

-    if (error_code != JVMTI_ERROR_NONE)

+    if (error_code != JVMTI_ERROR_NONE || NULL == class_name)

     {

         return UNKNOWN_CLASS_NAME;

     }

@@ -1081,26 +1101,10 @@ static char *get_main_class(

     string_replace(class_name, '.', '/');

     jclass cls = (*jni_env)->FindClass(jni_env, class_name);

-    /* Throws:

-     * ClassFormatError: if the class data does not specify a valid class. 

-     * ClassCircularityError: if a class or interface would be its own superclass or superinterface. 

-     * NoClassDefFoundError: if no definition for a requested class or interface can be found. 

-     * OutOfMemoryError: if the system runs out of memory.

-     */

-

-    jthrowable exception;

-    exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (exception)

+    if (check_and_clear_exception(jni_env) || cls == NULL)

     {

-        (*jni_env)->ExceptionClear(jni_env);

-    }

-

-    if (cls == NULL)

-    {

-        if (class_name != NULL)

-        {

-            (*jvmti_env)->Deallocate(jvmti_env, (unsigned char*)class_name);

-        }

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of %s\n", class_name);

+        (*jvmti_env)->Deallocate(jvmti_env, (unsigned char*)class_name);

         return UNKNOWN_CLASS_NAME;

     }

@@ -1428,6 +1432,7 @@ static char* get_path_to_class_class_loader(

             char     *class_name,

             const char *stringize_method_name)

 {

+    char *out = NULL;

     jclass class_loader_class = NULL;

     char *upd_class_name = (char*)malloc(strlen(class_name) + sizeof("class") + 1);

@@ -1442,47 +1447,18 @@ static char* get_path_to_class_class_loader(

     /* find ClassLoader class */

     class_loader_class = (*jni_env)->FindClass(jni_env, "java/lang/ClassLoader");

-    /* Throws:

-     * ClassFormatError: if the class data does not specify a valid class. 

-     * ClassCircularityError: if a class or interface would be its own superclass or superinterface. 

-     * NoClassDefFoundError: if no definition for a requested class or interface can be found. 

-     * OutOfMemoryError: if the system runs out of memory.

-     */

-

-    /* check if exception was thrown from FindClass() method */

-    jthrowable exception;

-    exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (exception)

-    {

-        (*jni_env)->ExceptionClear(jni_env);

-        free(upd_class_name);

-        return NULL;

-    }

-

-    if (class_loader_class ==  NULL)

+    if (check_and_clear_exception(jni_env) || class_loader_class ==  NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of java/lang/ClassLoader\n");

         free(upd_class_name);

         return NULL;

     }

     /* find method ClassLoader.getResource() */

-    jmethodID get_resource = (*jni_env)->GetMethodID(jni_env, class_loader_class, "getResource", "(Ljava/lang/String;)Ljava/net/URL;" );

-    /* Throws:

-     * NoSuchMethodError: if the specified method cannot be found. 

-     * ExceptionInInitializerError: if the class initializer fails due to an exception. 

-     * OutOfMemoryError: if the system runs out of memory.

-     */

-

-    exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (exception)

-    {

-        free(upd_class_name);

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        return NULL;

-    }

-

-    if (get_resource ==  NULL)

+    jmethodID get_resource = (*jni_env)->GetMethodID(jni_env, class_loader_class, "getResource", "(Ljava/lang/String;)Ljava/net/URL;");

+    if (check_and_clear_exception(jni_env) || get_resource ==  NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of java/lang/ClassLoader.getResource(Ljava/lang/String;)Ljava/net/URL;\n");

         free(upd_class_name);

         (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

         return NULL;

@@ -1491,52 +1467,46 @@ static char* get_path_to_class_class_loader(

     /* convert new class name into a Java String */

     jstring j_class_name = (*jni_env)->NewStringUTF(jni_env, upd_class_name);

     free(upd_class_name);

+    if (check_and_clear_exception(jni_env))

+    {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not allocate a new UTF string for '%s'\n", upd_class_name);

+        goto get_path_to_class_class_loader_lcl_refs_cleanup;

+    }

     /* call method ClassLoader.getResource(className) */

     jobject url = (*jni_env)->CallObjectMethod(jni_env, class_loader, get_resource, j_class_name);

-    if ((*jni_env)->ExceptionCheck(jni_env))

+    if (check_and_clear_exception(jni_env) || NULL == url)

     {

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        (*jni_env)->DeleteLocalRef(jni_env, j_class_name);

-        (*jni_env)->ExceptionClear(jni_env);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get a resource of %s\n", class_name);

+        goto get_path_to_class_class_loader_lcl_refs_cleanup;

     }

-    if (url ==  NULL)

+

+    /* find method URL.toString() */

+    jclass url_class = (*jni_env)->FindClass(jni_env, "java/net/URL");

+    if (check_and_clear_exception(jni_env) || NULL == url_class)

     {

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        (*jni_env)->DeleteLocalRef(jni_env, j_class_name);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of java/net/URL\n");

+        goto get_path_to_class_class_loader_lcl_refs_cleanup;

     }

-    /* find method URL.toString() */

-    jmethodID to_external_form = (*jni_env)->GetMethodID(jni_env, (*jni_env)->FindClass(jni_env, "java/net/URL"), stringize_method_name, "()Ljava/lang/String;" );

-    /* Throws:

-     * NoSuchMethodError: if the specified method cannot be found. 

-     * ExceptionInInitializerError: if the class initializer fails due to an exception. 

-     * OutOfMemoryError: if the system runs out of memory.

-     */

-    exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (exception)

+    jmethodID to_external_form = (*jni_env)->GetMethodID(jni_env, url_class, stringize_method_name, "()Ljava/lang/String;");

+    if (check_and_clear_exception(jni_env) || NULL == to_external_form)

     {

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        (*jni_env)->DeleteLocalRef(jni_env, j_class_name);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of java/net/URL.%s()Ljava/lang/String;\n", stringize_method_name);

+        goto get_path_to_class_class_loader_lcl_refs_cleanup;

     }

     /* call method URL.toString() */

     jstring jstr = (jstring)(*jni_env)->CallObjectMethod(jni_env, url, to_external_form);

-    /* no exception expected */

-

-    if (jstr ==  NULL)

+    if (check_and_clear_exception(jni_env) || jstr ==  NULL)

     {

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        (*jni_env)->DeleteLocalRef(jni_env, j_class_name);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Failed to convert an URL object to a string\n");

+        goto get_path_to_class_class_loader_lcl_refs_cleanup;

     }

     /* convert Java String into C char* */

     char *str = (char*)(*jni_env)->GetStringUTFChars(jni_env, jstr, NULL);

-    char *out = strdup(str);

+    out = strdup(str);

     if (out == NULL)

     {

         fprintf(stderr, "strdup(): out of memory");

@@ -1544,6 +1514,8 @@ static char* get_path_to_class_class_loader(

     /* cleanup */

     (*jni_env)->ReleaseStringUTFChars(jni_env, jstr, str);

+

+get_path_to_class_class_loader_lcl_refs_cleanup:

     (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

     (*jni_env)->DeleteLocalRef(jni_env, j_class_name);

     return out;

@@ -1558,39 +1530,30 @@ static jobject get_system_class_loader(

             jvmtiEnv *jvmti_env __UNUSED_VAR,

             JNIEnv   *jni_env)

 {

+    jobject system_class_loader = NULL;

+

     jclass class_loader_class = (*jni_env)->FindClass(jni_env, "java/lang/ClassLoader");

-    if (NULL == class_loader_class)

+    if (check_and_clear_exception(jni_env) || NULL == class_loader_class)

     {

-        VERBOSE_PRINT("Cannot find java/lang/ClassLoader class\n");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of java/lang/ClassLoader\n");

         return NULL;

     }

     jmethodID get_system_class_loader_smethod =(*jni_env)->GetStaticMethodID(jni_env, class_loader_class, "getSystemClassLoader", "()Ljava/lang/ClassLoader;");

-    jthrowable exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (NULL != exception)

-    {

-        VERBOSE_PRINT("Exception occured: can not get method java.lang.ClassLoader.getSystemClassLoader()\n");

-        (*jni_env)->ExceptionClear(jni_env);

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        return NULL;

-    }

-    if (NULL == get_system_class_loader_smethod)

+    if (check_and_clear_exception(jni_env) || NULL == get_system_class_loader_smethod)

     {

-        VERBOSE_PRINT("Cannot find java.lang.ClassLoader.getSystemClassLoader()Ljava/lang/ClassLoader;\n");

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not find method java.lang.ClassLoader.getSystemClassLoader()Ljava/lang/ClassLoader;\n");

+        goto get_system_class_loader_cleanup;

     }

-    jobject system_class_loader = (*jni_env)->CallStaticObjectMethod(jni_env, class_loader_class, get_system_class_loader_smethod);

-    exception = (*jni_env)->ExceptionOccurred(jni_env);

-    if (NULL != exception)

+    system_class_loader = (*jni_env)->CallStaticObjectMethod(jni_env, class_loader_class, get_system_class_loader_smethod);

+    if (check_and_clear_exception(jni_env))

     {

-        VERBOSE_PRINT("java.lang.ClassLoader.getSystemClassLoader() thrown an exception\n");

-        (*jni_env)->ExceptionClear(jni_env);

-        (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

-        return NULL;

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Exception occurred: Cannot get the system class loader\n");

+        goto get_system_class_loader_cleanup;

     }

+get_system_class_loader_cleanup:

     (*jni_env)->DeleteLocalRef(jni_env, class_loader_class);

     return system_class_loader;

 }

@@ -1613,12 +1576,12 @@ static char* get_path_to_class(

     /* class is loaded using boot classloader */

     if (class_loader == NULL)

     {

-        VERBOSE_PRINT("A class has not been loaded by a ClassLoader. Going to use the system class loader.\n");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": A class has not been loaded by a ClassLoader. Going to use the system class loader.\n");

         class_loader = get_system_class_loader(jvmti_env, jni_env);

         if (NULL == class_loader)

         {

-            VERBOSE_PRINT("Cannot get the system class loader.");

+            VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Cannot get the system class loader.");

             return NULL;

         }

     }

@@ -1642,16 +1605,16 @@ static jclass find_class_in_loaded_class(

     }

     jclass class_class = (*jni_env)->FindClass(jni_env, "java/lang/Class");

-    if (NULL == class_class)

+    if (check_and_clear_exception(jni_env) || NULL == class_class)

     {

-        VERBOSE_PRINT("Cannot find java/lang/Class class");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of java/lang/Class\n");

         goto find_class_in_loaded_class_cleanup;

     }

     jmethodID get_name_method = (*jni_env)->GetMethodID(jni_env, class_class, "getName", "()Ljava/lang/String;");

-    if (NULL == get_name_method)

+    if (check_and_clear_exception(jni_env) || NULL == get_name_method)

     {

-        VERBOSE_PRINT("Cannot find java.lang.Class.getName.()Ljava/lang/String;");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of java/lang/Class.getName()Ljava/lang/String;\n");

         (*jni_env)->DeleteLocalRef(jni_env, class_class);

         goto find_class_in_loaded_class_cleanup;

     }

@@ -1659,8 +1622,9 @@ static jclass find_class_in_loaded_class(

     for (jint i = 0; NULL == result && i < num_classes; ++i)

     {

         jobject class_name = (*jni_env)->CallObjectMethod(jni_env, loaded_classes[i], get_name_method);

-        if (NULL == class_name)

+        if (check_and_clear_exception(jni_env) || NULL == class_name)

         {

+            VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get name of a loaded class\n");

             continue;

         }

@@ -1697,21 +1661,17 @@ static int print_stack_trace_element(

 {

     jclass stack_frame_class = (*jni_env)->GetObjectClass(jni_env, stack_frame);

     jmethodID get_class_name_method = (*jni_env)->GetMethodID(jni_env, stack_frame_class, "getClassName", "()Ljava/lang/String;");

-    if (get_class_name_method == NULL)

+    if (check_and_clear_exception(jni_env) || get_class_name_method == NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of $(Frame class).getClassName()Ljava/lang/String;\n");

         (*jni_env)->DeleteLocalRef(jni_env, stack_frame_class);

         return -1;

     }

     jstring class_name_of_frame_method = (*jni_env)->CallObjectMethod(jni_env, stack_frame, get_class_name_method);

-    if ((*jni_env)->ExceptionOccurred(jni_env))

-    {

-        (*jni_env)->DeleteLocalRef(jni_env, stack_frame_class);

-        (*jni_env)->ExceptionClear(jni_env);

-        return -1;

-    }

-    if (class_name_of_frame_method == NULL)

+    if (check_and_clear_exception(jni_env) || class_name_of_frame_method == NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class name of a class on a frame\n");

         (*jni_env)->DeleteLocalRef(jni_env, stack_frame_class);

         return -1;

     }

@@ -1721,11 +1681,9 @@ static int print_stack_trace_element(

     jclass class_of_frame_method = (*jni_env)->FindClass(jni_env, cls_name_str);

     char *class_location = NULL;

-    if ((*jni_env)->ExceptionOccurred(jni_env))

+    if (check_and_clear_exception(jni_env) || NULL == class_of_frame_method)

     {

-        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": FindClass(%s) thrown an exception\n", cls_name_str);

-        (*jni_env)->ExceptionClear(jni_env);

-

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get class of %s. Try more hard by searching in the loaded classes.\n", cls_name_str);

         string_replace(cls_name_str, '/', '.');

         class_of_frame_method = find_class_in_loaded_class(jvmti_env, jni_env, cls_name_str);

         string_replace(cls_name_str, '.', '/');

@@ -1753,20 +1711,16 @@ static int print_stack_trace_element(

     jmethodID to_string_method = (*jni_env)->GetMethodID(jni_env, stack_frame_class, "toString", "()Ljava/lang/String;");

     (*jni_env)->DeleteLocalRef(jni_env, stack_frame_class);

-    if (to_string_method == NULL)

+    if (check_and_clear_exception(jni_env) || to_string_method == NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of $(Frame class).toString()Ljava/lang/String;\n");

         return -1;

     }

     jobject orig_str = (*jni_env)->CallObjectMethod(jni_env, stack_frame, to_string_method);

-    if ((*jni_env)->ExceptionOccurred(jni_env))

-    {

-        (*jni_env)->DeleteLocalRef(jni_env, orig_str);

-        (*jni_env)->ExceptionClear(jni_env);

-        return -1;

-    }

-    if (orig_str == NULL)

+    if (check_and_clear_exception(jni_env) || NULL == orig_str)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get a string representation of a class on a frame\n");

         (*jni_env)->DeleteLocalRef(jni_env, orig_str);

         return -1;

     }

@@ -1801,21 +1755,17 @@ static int print_exception_stack_trace(

     jclass exception_class = (*jni_env)->GetObjectClass(jni_env, exception);

     jmethodID to_string_method = (*jni_env)->GetMethodID(jni_env, exception_class, "toString", "()Ljava/lang/String;");

-    if (to_string_method == NULL)

+    if (check_and_clear_exception(jni_env) || to_string_method == NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of $(Exception class).toString()Ljava/lang/String;\n");

         (*jni_env)->DeleteLocalRef(jni_env, exception_class);

         return -1;

     }

     jobject exception_str = (*jni_env)->CallObjectMethod(jni_env, exception, to_string_method);

-    if ((*jni_env)->ExceptionCheck(jni_env))

-    {

-        (*jni_env)->DeleteLocalRef(jni_env, exception_class);

-        (*jni_env)->ExceptionClear(jni_env);

-        return -1;

-    }

-    if (exception_str == NULL)

+    if (check_and_clear_exception(jni_env) || exception_str == NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get a string representation of a class on a frame\n");

         (*jni_env)->DeleteLocalRef(jni_env, exception_class);

         return -1;

     }

@@ -1840,26 +1790,23 @@ static int print_exception_stack_trace(

     jmethodID get_stack_trace_method = (*jni_env)->GetMethodID(jni_env, exception_class, "getStackTrace", "()[Ljava/lang/StackTraceElement;");

     (*jni_env)->DeleteLocalRef(jni_env, exception_class);

-    if (get_stack_trace_method == NULL)

+    if (check_and_clear_exception(jni_env) || get_stack_trace_method == NULL)

     {

-        VERBOSE_PRINT("Cannot get getStackTrace() method id");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of $(Exception class).getStackTrace()[Ljava/lang/StackTraceElement;\n");

         return wrote;

     }

     jobject stack_trace_array = (*jni_env)->CallObjectMethod(jni_env, exception, get_stack_trace_method);

-    if ((*jni_env)->ExceptionCheck(jni_env))

-    {

-        (*jni_env)->ExceptionClear(jni_env);

-        return wrote;

-    }

-    if (stack_trace_array ==  NULL)

+    if (check_and_clear_exception(jni_env) || stack_trace_array ==  NULL)

     {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get a stack trace from an exception object\n");

         return wrote;

     }

     jint array_size = (*jni_env)->GetArrayLength(jni_env, stack_trace_array);

     for (jint i = 0; i < array_size; ++i)

     {

+        /* Throws only ArrayIndexOutOfBoundsException and this should not happen */

         jobject frame_element = (*jni_env)->GetObjectArrayElement(jni_env, stack_trace_array, i);

         const int frame_wrote = print_stack_trace_element(jvmti_env,

@@ -1918,23 +1865,30 @@ static char *generate_thread_stack_trace(

     wrote += exception_wrote;

+    /* GetObjectClass() throws nothing */

     jclass exception_class = (*jni_env)->GetObjectClass(jni_env, exception);

     if (NULL == exception_class)

     {

-        VERBOSE_PRINT("Cannot get class of an object\n");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Cannot get class of an object\n");

         return stack_trace_str;

     }

     jmethodID get_cause_method = (*jni_env)->GetMethodID(jni_env, exception_class, "getCause", "()Ljava/lang/Throwable;");

     (*jni_env)->DeleteLocalRef(jni_env, exception_class);

-    if (NULL == get_cause_method)

+    if (check_and_clear_exception(jni_env) || NULL == get_cause_method)

     {

-        VERBOSE_PRINT("Cannot find get an id of getCause()Ljava/lang/Throwable; method\n");

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Could not get methodID of $(Exception class).getCause()Ljava/lang/Throwable;\n");

         return stack_trace_str;

     }

     jobject cause = (*jni_env)->CallObjectMethod(jni_env, exception, get_cause_method);

+    if (check_and_clear_exception(jni_env))

+    {

+        VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Failed to get an inner exception of the top most one;\n");

+        return stack_trace_str;

+    }

+

     while (NULL != cause)

     {

         if ((size_t)(MAX_STACK_TRACE_STRING_LENGTH - wrote) < (sizeof(CAUSED_STACK_TRACE_HEADER) - 1))

@@ -1965,6 +1919,11 @@ static char *generate_thread_stack_trace(

         jobject next_cause = (*jni_env)->CallObjectMethod(jni_env, cause, get_cause_method);

         (*jni_env)->DeleteLocalRef(jni_env, cause);

+        if (check_and_clear_exception(jni_env))

+        {

+            VERBOSE_PRINT(__FILE__ ":" STRINGIZE(__LINE__)": Failed to get an inner exception of another inner one;\n");

+            return stack_trace_str;

+        }

         cause = next_cause;

     }

@@ -2318,14 +2277,14 @@ static void JNICALL callback_on_exception_catch(

     }

     jclass object_class = (*jni_env)->FindClass(jni_env, "java/lang/Object");

-    if (NULL == object_class)

+    if (check_and_clear_exception(jni_env) || NULL == object_class)

     {

         VERBOSE_PRINT("Cannot find java/lang/Object class");

         goto callback_on_exception_catch_exit;

     }

     jmethodID equal_method = (*jni_env)->GetMethodID(jni_env, object_class, "equals", "(Ljava/lang/Object;)Z");

-    if (NULL == equal_method)

+    if (check_and_clear_exception(jni_env) || NULL == equal_method)

     {

         VERBOSE_PRINT("Cannot find java.lang.Object.equals(Ljava/lang/Object;)Z method");

         (*jni_env)->DeleteLocalRef(jni_env, object_class);

@@ -2333,8 +2292,12 @@ static void JNICALL callback_on_exception_catch(

     }

     jboolean equal_objects = (*jni_env)->CallBooleanMethod(jni_env, exception_object, equal_method, rpt->exception_object);

-    if (!equal_objects)

+    if (check_and_clear_exception(jni_env) || !equal_objects)

+    {

+        VERBOSE_PRINT("Cannot determine whether the caught exception is also the uncaught exception");

+        (*jni_env)->DeleteLocalRef(jni_env, object_class);

         goto callback_on_exception_catch_exit;

+    }

     /* Faster than get()-pop() approach is faster because it is search-and-search-free but

      * pop()-push() approach is search-free-and-search-malloc

diff --git a/src/jthrowable_circular_buf.c b/src/jthrowable_circular_buf.c

index e13801c..64f0f30 100644

--- a/src/jthrowable_circular_buf.c

+++ b/src/jthrowable_circular_buf.c

@@ -162,6 +162,16 @@ static int jthrowable_circular_buf_find_index(T_jthrowableCircularBuf *buffer, j

     }

     jclass object_class = (*buffer->jni_env)->FindClass(buffer->jni_env, "java/lang/Object");

+    if ((*buffer->jni_env)->ExceptionOccurred(buffer->jni_env))

+    {

+        VERBOSE_PRINT("Cannot find java/lang/Object class\n");

+#ifdef VERBOSE

+        (*buffer->jni_env)->ExceptionDescribe(buffer->jni_env);

+#endif

+        (*buffer->jni_env)->ExceptionClear(buffer->jni_env);

+        return 1;

+    }

+

     if (NULL == object_class)

     {

         VERBOSE_PRINT("Cannot find java/lang/Object class");

@@ -169,6 +179,16 @@ static int jthrowable_circular_buf_find_index(T_jthrowableCircularBuf *buffer, j

     }

     jmethodID equal_method = (*buffer->jni_env)->GetMethodID(buffer->jni_env, object_class, "equals", "(Ljava/lang/Object;)Z");

+    if ((*buffer->jni_env)->ExceptionOccurred(buffer->jni_env))

+    {

+        VERBOSE_PRINT("Cannot find java.lang.Object.equals(Ljava/lang/Object;)Z method\n");

+#ifdef VERBOSE

+        (*buffer->jni_env)->ExceptionDescribe(buffer->jni_env);

+#endif

+        (*buffer->jni_env)->ExceptionClear(buffer->jni_env);

+        return 1;

+    }

+

     if (NULL == equal_method)

     {

         VERBOSE_PRINT("Cannot find java.lang.Object.equals(Ljava/lang/Object;)Z method");

@@ -182,10 +202,24 @@ static int jthrowable_circular_buf_find_index(T_jthrowableCircularBuf *buffer, j

     for (size_t i = rbegin; /* break inside */; i = jthrowable_circular_buf_get_index(buffer, (i - 1)))

     {

         VERBOSE_PRINT("Checking next exception object %p\n", (void *)buffer->mem[i]);

-        if (NULL != buffer->mem[i] && (*buffer->jni_env)->CallBooleanMethod(buffer->jni_env, buffer->mem[i], equal_method, exception))

+        if (NULL != buffer->mem[i])

         {

-            *index = i;

-            return 0;

+            jboolean equals = (*buffer->jni_env)->CallBooleanMethod(buffer->jni_env, buffer->mem[i], equal_method, exception);

+            if ((*buffer->jni_env)->ExceptionOccurred(buffer->jni_env))

+            {

+                VERBOSE_PRINT("Cannot determine whether objects are equal\n");

+#ifdef VERBOSE

+                (*buffer->jni_env)->ExceptionDescribe(buffer->jni_env);

+#endif

+                (*buffer->jni_env)->ExceptionClear(buffer->jni_env);

+                return 1;

+            }

+

+            if (equals)

+            {

+                *index = i;

+                return 0;

+            }

         }

         if (rend == i)

-- 

1.8.3.1