KSCrash-源码阅读-4 NSEexption

添加NsException 自定义处理入口

  1. NSGetUncaughtExceptionHandler() 获取已经添加的处理入口
  2. NSSetUncaughtExceptionHandler(&handleUncaughtException) 添加自己的异常处理入口
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    static void setEnabled(bool isEnabled)
    {
        if(isEnabled != g_isEnabled)
        {
            g_isEnabled = isEnabled;
            if(isEnabled)
            {
                KSLOG_DEBUG(@"Backing up original handler.");
                g_previousUncaughtExceptionHandler = NSGetUncaughtExceptionHandler();
                
                KSLOG_DEBUG(@"Setting new handler.");
                NSSetUncaughtExceptionHandler(&handleUncaughtException);
                KSCrash.sharedInstance.uncaughtExceptionHandler = &handleUncaughtException;
                KSCrash.sharedInstance.currentSnapshotUserReportedExceptionHandler = &handleCurrentSnapshotUserReportedException;
            }
            else
            {
                KSLOG_DEBUG(@"Restoring original handler.");
                NSSetUncaughtExceptionHandler(g_previousUncaughtExceptionHandler);
            }
        }
    }

    异常处理入口

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    // ============================================================================

    /** Our custom excepetion handler.
     * Fetch the stack trace from the exception and write a report.
     *
     * @param exception The exception that was raised.
     */

    static void handleException(NSException* exception, BOOL currentSnapshotUserReported) {
        KSLOG_DEBUG(@"Trapped exception %@", exception);
        if(g_isEnabled)
        {
            thread_act_array_t threads = NULL;
            mach_msg_type_number_t numThreads = 0;
            ksmc_suspendEnvironment(&threads, &numThreads);
            kscm_notifyFatalExceptionCaptured(false);

            KSLOG_DEBUG(@"Filling out context.");
            NSArray* addresses = [exception callStackReturnAddresses];
            NSUInteger numFrames = addresses.count;
            uintptr_t* callstack = malloc(numFrames * sizeof(*callstack));
            for(NSUInteger i = 0; i < numFrames; i++)
            {
                callstack[i] = (uintptr_t)[addresses[i] unsignedLongLongValue];
            }

            char eventID[37];
            ksid_generate(eventID);
            KSMC_NEW_CONTEXT(machineContext);
            ksmc_getContextForThread(ksthread_self(), machineContext, true);
            KSStackCursor cursor;
            kssc_initWithBacktrace(&cursor, callstack, (int)numFrames, 0);

            KSCrash_MonitorContext* crashContext = &g_monitorContext;
            memset(crashContext, 0, sizeof(*crashContext));
            crashContext->crashType = KSCrashMonitorTypeNSException;
            crashContext->eventID = eventID;
            crashContext->offendingMachineContext = machineContext;
            crashContext->registersAreValid = false;
            crashContext->NSException.name = [[exception name] UTF8String];
            crashContext->NSException.userInfo = [[NSString stringWithFormat:@"%@", exception.userInfo] UTF8String];
            crashContext->exceptionName = crashContext->NSException.name;
            crashContext->crashReason = [[exception reason] UTF8String];
            crashContext->stackCursor = &cursor;
            crashContext->currentSnapshotUserReported = currentSnapshotUserReported;

            KSLOG_DEBUG(@"Calling main crash handler.");
            kscm_handleException(crashContext);

            free(callstack);
            if (currentSnapshotUserReported) {
                ksmc_resumeEnvironment(threads, numThreads);
            }
            if (g_previousUncaughtExceptionHandler != NULL)
            {
                KSLOG_DEBUG(@"Calling original exception handler.");
                g_previousUncaughtExceptionHandler(exception);
            }
        }
    }