fix(unwind): fallback to dladdr in the crash unwinder when a stack …

…frames `filename` or `method` cannot be located in our cached data

Makefile

@@ -32,16 +32,18 @@ test-fixtures:
 	@cp features/fixtures/mazerunner/app/build/outputs/apk/release/fixture.apk build/fixture.apk
 	# copy the unstripped scenarios libs (for stack unwinding validation)
 	# grabs the newest files as the likely just built ones
-	LIB_CXX_BUGSNAG=$$(ls -dtr features/fixtures/mazerunner/cxx-scenarios-bugsnag/build/intermediates/cxx/RelWithDebInfo/* | head -n 1) && \
-	LIB_CXX=$$(ls -dtr features/fixtures/mazerunner/cxx-scenarios/build/intermediates/cxx/RelWithDebInfo/* | head -n 1) && \
-		cp $$LIB_CXX/obj/x86_64/libcxx-scenarios.so build/libcxx-scenarios-x86_64.so && \
-		cp $$LIB_CXX/obj/x86/libcxx-scenarios.so build/libcxx-scenarios-x86.so && \
-		cp $$LIB_CXX/obj/arm64-v8a/libcxx-scenarios.so build/libcxx-scenarios-arm64.so && \
-		cp $$LIB_CXX/obj/armeabi-v7a/libcxx-scenarios.so build/libcxx-scenarios-arm32.so && \
-		cp $$LIB_CXX_BUGSNAG/obj/x86_64/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-x86_64.so && \
-		cp $$LIB_CXX_BUGSNAG/obj/x86/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-x86.so && \
-		cp $$LIB_CXX_BUGSNAG/obj/arm64-v8a/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-arm64.so && \
-		cp $$LIB_CXX_BUGSNAG/obj/armeabi-v7a/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-arm32.so
+	LIB_CXX_BUGSNAG_64=$$(dirname `ls -dtr features/fixtures/mazerunner/cxx-scenarios-bugsnag/build/intermediates/cxx/RelWithDebInfo/*/obj/x86_64 | head -n 1`) && \
+	LIB_CXX_BUGSNAG_32=$$(dirname `ls -dtr features/fixtures/mazerunner/cxx-scenarios-bugsnag/build/intermediates/cxx/RelWithDebInfo/*/obj/armeabi-v7a | head -n 1`) && \
+	LIB_CXX_64=$$(dirname `ls -dtr features/fixtures/mazerunner/cxx-scenarios/build/intermediates/cxx/RelWithDebInfo/*/obj/x86_64 | head -n 1`) && \
+	LIB_CXX_32=$$(dirname `ls -dtr features/fixtures/mazerunner/cxx-scenarios/build/intermediates/cxx/RelWithDebInfo/*/obj/armeabi-v7a | head -n 1`) && \
+		cp $$LIB_CXX_64/x86_64/libcxx-scenarios.so build/libcxx-scenarios-x86_64.so && \
+		cp $$LIB_CXX_32/x86/libcxx-scenarios.so build/libcxx-scenarios-x86.so && \
+		cp $$LIB_CXX_64/arm64-v8a/libcxx-scenarios.so build/libcxx-scenarios-arm64.so && \
+		cp $$LIB_CXX_32/armeabi-v7a/libcxx-scenarios.so build/libcxx-scenarios-arm32.so && \
+		cp $$LIB_CXX_BUGSNAG_64/x86_64/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-x86_64.so && \
+		cp $$LIB_CXX_BUGSNAG_32/x86/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-x86.so && \
+		cp $$LIB_CXX_BUGSNAG_64/arm64-v8a/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-arm64.so && \
+		cp $$LIB_CXX_BUGSNAG_32/armeabi-v7a/libcxx-scenarios-bugsnag.so build/libcxx-scenarios-bugsnag-arm32.so
 
 	# And the minimal (no NDK or ANR plugin) test fixture
 	@./gradlew -PMINIMAL_FIXTURE=true -PTEST_FIXTURE_NAME=fixture-minimal.apk  -p=features/fixtures/mazerunner/ assembleRelease -x check

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

@@ -2,6 +2,7 @@
 
 #include "string.h"
 
+#include <dlfcn.h>
 #include <unwindstack/LocalUnwinder.h>
 #include <unwindstack/Maps.h>
 #include <unwindstack/MemoryLocal.h>
@@ -73,6 +74,23 @@ ssize_t bsg_unwind_crash_stack(bugsnag_stackframe stack[BUGSNAG_FRAMES_MAX],
                 sizeof(stack[frame_count].filename));
     bsg_strncpy(stack[frame_count].method, frame.function_name.c_str(),
                 sizeof(stack[frame_count].method));
+
+    // if the filename or method name cannot be found - try fallback to dladdr
+    // to find them
+    static Dl_info info;
+    if ((frame.map_name.empty() || frame.function_name.empty()) &&
+        dladdr((void *)frame.pc, &info) != 0) {
+
+      if (info.dli_fname != nullptr) {
+        bsg_strncpy(stack[frame_count].filename, (char *)info.dli_fname,
+                    sizeof(stack[frame_count].filename));
+      }
+      if (info.dli_sname != nullptr) {
+        bsg_strncpy(stack[frame_count].method, (char *)info.dli_sname,
+                    sizeof(stack[frame_count].method));
+      }
+    }
+
     frame_count++;
   }
   unwinding_crash_stack = false;

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

@@ -15,11 +15,8 @@ add_library(cxx-scenarios SHARED
         src/main/cpp/bugsnag-java-scenarios.cpp)
 
 set_target_properties(cxx-scenarios PROPERTIES
-                      CXX_STANDARD 11
-                      CXX_STANDARD_REQUIRED YES)
+        CXX_STANDARD 11
+        CXX_STANDARD_REQUIRED YES)
 
-add_library(lib_monochrome SHARED IMPORTED)
-set_target_properties(lib_monochrome PROPERTIES IMPORTED_LOCATION
-                      ${CMAKE_SOURCE_DIR}/libs/${ANDROID_ABI}/libmonochrome.so)
-target_link_libraries(cxx-scenarios lib_monochrome)
+target_link_libraries(cxx-scenarios)
 

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

@@ -1,13 +1,17 @@
 #include <jni.h>
 #include <cstdio>
+#include <dlfcn.h>
 
 extern "C" {
 // defined in libs/[ABI]/libmonochrome.so
-int something_innocuous(int input);
+int (*something_innocuous)(int input);
 
 JNIEXPORT int JNICALL
 Java_com_bugsnag_android_mazerunner_scenarios_CXXExternalStackElementScenario_crash(
     JNIEnv *env, jobject instance, jint counter) {
+  void *monochrome = dlopen("libmonochrome.so", RTLD_GLOBAL);
+  *(void**)(&something_innocuous) = dlsym(monochrome, "something_innocuous");
+
   printf("Captain, why are we out here chasing comets?\n%d\n", counter);
   int value = counter * 4;
   if (counter > 0) {

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

@@ -10,7 +10,6 @@
 public class CXXExternalStackElementScenario extends Scenario {
 
     static {
-        System.loadLibrary("monochrome");
         System.loadLibrary("cxx-scenarios");
     }
 

features/full_tests/native_crash_handling.feature

@@ -128,7 +128,7 @@ 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 | 14       |
+      | Java_com_bugsnag_android_mazerunner_scenarios_CXXExternalStackElementScenario_crash | CXXExternalStackElementScenario.cpp | 18       |
 
   Scenario: Call null function pointer
   A null pointer should be the first element of a stack trace,