feat(ndk): add bugsnag_refresh_symbol_table to force a reparse of d…

…ynamically linked modules

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 ## TBD
 
+### Enhancements
+
+* Introduced `bugsnag_refresh_symbol_table` and `BugsnagNDK.refreshSymbolTable` to allow NDK apps to force a refresh of cached
+  debug information used during a native crash. This new API is only applicable if you are using `dlopen` or `System.loadLibrary`
+  after startup, and experiencing native crashes with missing symbols.
+  [#1731](/~https://github.com/bugsnag/bugsnag-android/pull/1731)
+
 ### Bug fixes
 
 * Non-List Collections are now correctly handled as OPAQUE values for NDK metadata

bugsnag-plugin-android-ndk/src/main/assets/include/bugsnag.h

@@ -63,6 +63,14 @@ void bugsnag_add_on_error(bsg_on_error on_error);
  */
 void bugsnag_remove_on_error();
 
+/**
+ * Refresh cached symbol tables within Bugsnag. This can be used to force a
+ * refresh of the cached symbols used during stack unwinding. This is only
+ * useful if you are using `System.loadLibrary` or `dlopen` after your
+ * application startup is complete.
+ */
+void bugsnag_refresh_symbol_table();
+
 #ifdef __cplusplus
 }
 #endif

bugsnag-plugin-android-ndk/src/main/java/com/bugsnag/android/NdkPlugin.kt

@@ -18,9 +18,11 @@ internal class NdkPlugin : Plugin {
 
     private external fun getBinaryArch(): String
 
-    private var nativeBridge: NativeBridge? = null
     private var client: Client? = null
 
+    var nativeBridge: NativeBridge? = null
+        private set
+
     private fun initNativeBridge(client: Client): NativeBridge {
         val nativeBridge = NativeBridge()
         client.addObserver(nativeBridge)
@@ -72,3 +74,6 @@ internal class NdkPlugin : Plugin {
         return 0
     }
 }
+
+internal val Client.ndkPlugin: NdkPlugin?
+    get() = getPlugin(NdkPlugin::class.java) as NdkPlugin?

bugsnag-plugin-android-ndk/src/main/java/com/bugsnag/android/ndk/BugsnagNDK.kt

@@ -0,0 +1,14 @@
+package com.bugsnag.android.ndk
+
+import com.bugsnag.android.Bugsnag
+import com.bugsnag.android.ndkPlugin
+
+object BugsnagNDK {
+    @JvmStatic
+    fun refreshSymbolTable() {
+        if (Bugsnag.isStarted()) {
+            val client = Bugsnag.getClient()
+            client.ndkPlugin?.nativeBridge?.refreshSymbolTable()
+        }
+    }
+}

bugsnag-plugin-android-ndk/src/main/java/com/bugsnag/android/ndk/NativeBridge.kt

@@ -82,6 +82,7 @@ class NativeBridge : StateObserver {
     external fun addFeatureFlag(name: String, variant: String?)
     external fun clearFeatureFlag(name: String)
     external fun clearFeatureFlags()
+    external fun refreshSymbolTable()
 
     override fun onStateChange(event: StateEvent) {
         if (isInvalidMessage(event)) return

bugsnag-plugin-android-ndk/src/main/jni/bugsnag_ndk.c

@@ -51,6 +51,8 @@ void bugsnag_remove_on_error() {
   }
 }
 
+void bugsnag_refresh_symbol_table() { bsg_unwinder_refresh(); }
+
 bool bsg_run_on_error() {
   bsg_on_error on_error = bsg_global_env->on_error;
   if (on_error != NULL) {
@@ -495,6 +497,10 @@ Java_com_bugsnag_android_ndk_NativeBridge_updateIsLaunching(
   bugsnag_app_set_is_launching(&bsg_global_env->next_event, new_value);
   bsg_update_next_run_info(bsg_global_env);
   release_env_write_lock();
+
+  if (!new_value) {
+    bugsnag_refresh_symbol_table();
+  }
 }
 
 JNIEXPORT void JNICALL
@@ -806,6 +812,12 @@ Java_com_bugsnag_android_ndk_NativeBridge_clearFeatureFlags(JNIEnv *env,
   release_env_write_lock();
 }
 
+JNIEXPORT void JNICALL
+Java_com_bugsnag_android_ndk_NativeBridge_refreshSymbolTable(JNIEnv *env,
+                                                             jobject thiz) {
+  bugsnag_refresh_symbol_table();
+}
+
 #ifdef __cplusplus
 }
 #endif

bugsnag-plugin-android-ndk/src/main/jni/utils/stack_unwinder.cpp

@@ -54,7 +54,7 @@ void bsg_unwinder_init() {
   }
   attempted_init = true;
 
-  auto crash_time_maps = new unwindstack::LocalMaps();
+  auto crash_time_maps = new unwindstack::LocalUpdatableMaps();
   if (crash_time_maps->Parse()) {
     std::shared_ptr<unwindstack::Memory> crash_time_memory(
         new unwindstack::MemoryLocal);
@@ -73,6 +73,18 @@ void bsg_unwinder_init() {
   }
 }
 
+void bsg_unwinder_refresh(void) {
+  if (crash_time_unwinder == nullptr) {
+    return;
+  }
+
+  auto *crash_time_maps = dynamic_cast<unwindstack::LocalUpdatableMaps *>(
+      crash_time_unwinder->GetMaps());
+  if (crash_time_maps != nullptr) {
+    crash_time_maps->Reparse(nullptr);
+  }
+}
+
 ssize_t bsg_unwind_crash_stack(bugsnag_stackframe stack[BUGSNAG_FRAMES_MAX],
                                siginfo_t *info, void *user_context) {
   if (crash_time_unwinder == nullptr || unwinding_crash_stack) {

bugsnag-plugin-android-ndk/src/main/jni/utils/stack_unwinder.h

@@ -13,6 +13,12 @@ extern "C" {
  */
 void bsg_unwinder_init(void);
 
+/**
+ * Refresh the stack unwinder. This can be called to force a refresh of any
+ * cached data within the unwinder.
+ */
+void bsg_unwinder_refresh(void);
+
 /**
  * Unwind a stack in a terminating context. If info and a user context pointer
  * are provided, the exception stack will be walked. Otherwise, the current

features/fixtures/mazerunner/cxx-scenarios-bugsnag/CMakeLists.txt

@@ -2,6 +2,7 @@ cmake_minimum_required(VERSION 3.4.1)
 
 add_library(cxx-scenarios-bugsnag SHARED
         src/main/cpp/cxx-scenarios-bugsnag.cpp
+        src/main/cpp/CXXExternalStackElementScenario.cpp
         src/main/cpp/CXXExceptionSmokeScenario.cpp)
 
 set_target_properties(cxx-scenarios-bugsnag PROPERTIES

features/fixtures/mazerunner/cxx-scenarios/src/main/cpp/CXXExternalStackElementScenario.cpp → features/fixtures/mazerunner/cxx-scenarios-bugsnag/src/main/cpp/CXXExternalStackElementScenario.cpp

@@ -1,6 +1,7 @@
 #include <jni.h>
 #include <cstdio>
 #include <dlfcn.h>
+#include <bugsnag.h>
 
 extern "C" {
 // defined in libs/[ABI]/libmonochrome.so
@@ -10,6 +11,7 @@ JNIEXPORT int JNICALL
 Java_com_bugsnag_android_mazerunner_scenarios_CXXExternalStackElementScenario_crash(
     JNIEnv *env, jobject instance, jint counter) {
   void *monochrome = dlopen("libmonochrome.so", RTLD_GLOBAL);
+  bugsnag_refresh_symbol_table();
   *(void**)(&something_innocuous) = dlsym(monochrome, "something_innocuous");
 
   printf("Captain, why are we out here chasing comets?\n%d\n", counter);

features/fixtures/mazerunner/cxx-scenarios/src/main/java/com/bugsnag/android/mazerunner/scenarios/CXXExternalStackElementScenario.java → features/fixtures/mazerunner/cxx-scenarios-bugsnag/src/main/java/com/bugsnag/android/mazerunner/scenarios/CXXExternalStackElementScenario.java

@@ -10,7 +10,8 @@
 public class CXXExternalStackElementScenario extends Scenario {
 
     static {
-        System.loadLibrary("cxx-scenarios");
+        System.loadLibrary("bugsnag-ndk");
+        System.loadLibrary("cxx-scenarios-bugsnag");
     }
 
     public native void crash(int counter);

features/fixtures/mazerunner/cxx-scenarios/CMakeLists.txt

@@ -5,7 +5,6 @@ add_library(cxx-scenarios SHARED
         src/main/cpp/CXXAbortScenario.cpp
         src/main/cpp/CXXCallNullFunctionPointerScenario.cpp
         src/main/cpp/CXXDereferenceNullScenario.cpp
-        src/main/cpp/CXXExternalStackElementScenario.cpp
         src/main/cpp/CXXImproperTypecastScenario.cpp
         src/main/cpp/CXXInvalidRethrow.cpp
         src/main/cpp/CXXStackoverflowScenario.cpp

features/full_tests/native_crash_handling.feature

@@ -137,7 +137,8 @@ Feature: Native crash reporting
     And the exception "type" equals "c"
     And the first significant stack frames match:
       | something_innocuous                                                                 | libmonochrome.so                    | (ignore) |
-      | Java_com_bugsnag_android_mazerunner_scenarios_CXXExternalStackElementScenario_crash | CXXExternalStackElementScenario.cpp | 18       |
+      | Java_com_bugsnag_android_mazerunner_scenarios_CXXExternalStackElementScenario_crash | CXXExternalStackElementScenario.cpp | 20       |
+    And the "codeIdentifier" of stack frame 0 is not null
 
   Scenario: Call null function pointer
   A null pointer should be the first element of a stack trace,