a little exception handling

launcher/CMakeLists.txt

@@ -28,6 +28,7 @@ if (NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
     add_link_options(-O3)
 endif ()
 
+add_subdirectory(utils)
 add_subdirectory(libjvm_wrapper)
 add_subdirectory(backend)
 add_subdirectory(gui)

launcher/backend/CMakeLists.txt

@@ -6,4 +6,4 @@ add_library(backend
 target_include_directories(backend PRIVATE include)
 target_include_directories(backend PUBLIC include_public)
 
-target_link_libraries(backend PUBLIC libjvm_wrapper)
+target_link_libraries(backend PUBLIC libjvm_wrapper utils)

launcher/backend/src/DhfsInstance.cpp

@@ -35,7 +35,7 @@ void DhfsInstance::start() {
     args.options = options.data();
     args.ignoreUnrecognized = false;
 
-    LibjvmWrapper::instance().JNI_CreateJavaVM(&_jvm, (void**) &_env, &args);
+    LibjvmWrapper::instance().WJNI_CreateJavaVM(&_jvm, (void**) &_env, &args);
 }
 
 void DhfsInstance::stop() {

launcher/gui/CMakeLists.txt

@@ -11,4 +11,4 @@ add_executable(launcher
 )
 
 target_link_libraries(launcher ${wxWidgets_LIBRARIES})
-target_link_libraries(launcher backend)
+target_link_libraries(launcher backend utils)

launcher/gui/src/LauncherApp.cpp

@@ -31,3 +31,12 @@ bool LauncherApp::OnInit() {
 
     return true;
 }
+
+bool LauncherApp::OnExceptionInMainLoop() {
+    try {
+        std::rethrow_exception(std::current_exception());
+    } catch (const std::exception& e) {
+        wxMessageBox(e.what(), "Error", wxOK | wxICON_ERROR | wxCENTRE, GetTopWindow());
+    }
+    return true;
+}

launcher/gui/src/LauncherApp.h

@@ -9,7 +9,9 @@
 // containing a statusbar with the text "Hello World"
 class LauncherApp : public wxApp {
 public:
-    virtual bool OnInit();
+    virtual bool OnInit() override;
+
+    virtual bool OnExceptionInMainLoop() override;
 };
 
 DECLARE_APP(LauncherApp)

launcher/libjvm_wrapper/CMakeLists.txt

@@ -7,4 +7,6 @@ target_include_directories(libjvm_wrapper PRIVATE include)
 target_include_directories(libjvm_wrapper PUBLIC include_public)
 
 find_package(JNI REQUIRED)
-target_include_directories(libjvm_wrapper PUBLIC ${JNI_INCLUDE_DIRS})
+target_include_directories(libjvm_wrapper PUBLIC ${JNI_INCLUDE_DIRS})
+
+target_link_libraries(libjvm_wrapper PUBLIC utils)

launcher/libjvm_wrapper/include_public/LibjvmWrapper.hpp

@@ -4,14 +4,14 @@
 
 #ifndef LIBJVMWRAPPER_HPP
 #define LIBJVMWRAPPER_HPP
-#include <jni.h>
 
+#include <jni.h>
 
 class LibjvmWrapper {
 public:
     static LibjvmWrapper& instance();
 
-    decltype(JNI_CreateJavaVM)* JNI_CreateJavaVM;
+    decltype(JNI_CreateJavaVM)* WJNI_CreateJavaVM;
 
 private:
     LibjvmWrapper();

launcher/libjvm_wrapper/src/LibjvmWrapper.cpp

@@ -6,6 +6,8 @@
 #include <dlfcn.h>
 #include <jni.h>
 
+#include "Exception.h"
+
 static constexpr auto LIBJVM_PATH =
         "/Library/Java/JavaVirtualMachines/zulu-21.jdk/Contents/Home/lib/server/libjvm.dylib";
 
@@ -16,8 +18,12 @@ LibjvmWrapper& LibjvmWrapper::instance() {
 
 LibjvmWrapper::LibjvmWrapper() {
     _lib_handle = dlopen(LIBJVM_PATH, RTLD_NOW | RTLD_GLOBAL);
-    JNI_CreateJavaVM = reinterpret_cast<decltype(JNI_CreateJavaVM)>(
+    if (_lib_handle == nullptr)
+        throw Exception(dlerror());
+    WJNI_CreateJavaVM = reinterpret_cast<decltype(WJNI_CreateJavaVM)>(
         dlsym(_lib_handle, "JNI_CreateJavaVM"));
+    if (WJNI_CreateJavaVM == nullptr)
+        throw Exception(dlerror());
 }
 
 LibjvmWrapper::~LibjvmWrapper() {

launcher/utils/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_library(utils
+        src/Exception.cpp
+        include_public/Exception.h
+)
+
+target_include_directories(utils PRIVATE include)
+target_include_directories(utils PUBLIC include_public)

launcher/utils/include_public/Exception.h

@@ -0,0 +1,30 @@
+//
+// Created by Stepan Usatiuk on 01.05.2023.
+//
+
+#ifndef SEMBACKUP_EXCEPTION_H
+#define SEMBACKUP_EXCEPTION_H
+
+#include <cstring>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+/// Custom exception class that uses execinfo to append a stacktrace to the exception message
+class Exception : public std::runtime_error {
+public:
+    Exception(const std::string& text);
+    Exception(const char* text);
+
+private:
+    /// Static function to get the current stacktrace
+    static std::string getStacktrace();
+};
+
+class ErrnoException : public Exception {
+public:
+    ErrnoException(const std::string& text) : Exception(text + " " + std::strerror(errno)) {}
+    ErrnoException(const char* text) : Exception(std::string(text) + " " + std::strerror(errno)) {}
+};
+
+#endif // SEMBACKUP_EXCEPTION_H

launcher/utils/src/Exception.cpp

@@ -0,0 +1,37 @@
+//
+// Created by Stepan Usatiuk on 01.05.2023.
+//
+
+#include "Exception.h"
+
+#include <execinfo.h>
+#include <sstream>
+
+#include <openssl/err.h>
+
+Exception::Exception(const std::string& text) : runtime_error(text + "\n" + getStacktrace()) {
+}
+
+Exception::Exception(const char* text) : runtime_error(std::string(text) + "\n" + getStacktrace()) {
+}
+
+// Based on: https://www.gnu.org/software/libc/manual/html_node/Backtraces.html
+std::string Exception::getStacktrace() {
+    std::vector<void*> functions(50);
+    char** strings;
+    int n;
+
+    n = backtrace(functions.data(), 50);
+    strings = backtrace_symbols(functions.data(), n);
+
+    std::stringstream out;
+
+    if (strings != nullptr) {
+        out << "Stacktrace:" << std::endl;
+        for (int i = 0; i < n; i++)
+            out << strings[i] << std::endl;
+    }
+
+    free(strings);
+    return out.str();
+}