Make Android startup crashes diagnosable: keep native symbols + in-process crash dumper to user-accessible file

osu.Android/Native/CMakeLists.txt

@@ -16,7 +16,20 @@ set(CMAKE_C_FLAGS_RELEASE   "-O3 -flto=thin -ffast-math -ffunction-sections -fda
 # -Wl,-z,max-page-size=16384: align ELF LOAD segments to 16 KB for Android 15+
 #   devices with 16 KB page sizes.  Without this, the .so will fail to load on
 #   such devices.  NDK r28+ supports this flag.
-set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "-Wl,--gc-sections -Wl,-z,max-page-size=16384 -s")
+#
+# IMPORTANT: do NOT pass `-s` (or `-Wl,-s`) here.  Stripping the native library
+# removes the symbol table, which means Android tombstones — and crash-report
+# tools like Crash Log Viewer that read them — print only `pc=<hex>` with no
+# function name.  That makes the SDLThread / audio-thread SIGSEGVs we have been
+# chasing essentially unfixable from a tombstone alone, because we cannot tell
+# whether the null indirect call originated in our `OboeBridge::onAudioReady`,
+# in Oboe itself, in libvulkan, or in the renderer.  Keeping symbols costs only
+# a few hundred KB in the on-device .so (and zero APK download size when LZ4
+# assembly compression is on, since the .so is also compressed), and it is the
+# single highest-leverage change we can make for diagnosing real-device crashes.
+# `-Wl,--gc-sections` still removes unreferenced sections; only the symbol
+# *names* are retained.
+set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "-Wl,--gc-sections -Wl,-z,max-page-size=16384")
 
 # Disable Oboe's flowgraph module — we don't use any audio processing/conversion
 # features (our bridge outputs silence for latency measurement only).
@@ -64,10 +77,15 @@ set(OBOE_LIB oboe)
 find_library(vulkan-lib vulkan REQUIRED)
 find_library(log-lib log REQUIRED)
 find_library(android-lib android REQUIRED)
+# `dl` is needed for dladdr() in crash_handler.cpp (symbol resolution from PCs).
+# It is normally auto-linked on Android, but make the dependency explicit so we
+# don't accidentally lose dladdr if the toolchain default ever changes.
+find_library(dl-lib dl REQUIRED)
 
 add_library(osu_native SHARED
     oboe_bridge.cpp
     vulkan_bridge.cpp
+    crash_handler.cpp
 )
 
 
@@ -76,4 +94,5 @@ target_link_libraries(osu_native
     ${vulkan-lib}
     ${log-lib}
     ${android-lib}
+    ${dl-lib}
 )

osu.Android/Native/OboeAudioBridge.cs

@@ -215,5 +215,6 @@ public void Dispose()
         [DllImport(lib_name)] internal static extern void nADPFReportActualDuration(IntPtr sessionPtr, long actualDurationNanos);
         [DllImport(lib_name)] internal static extern void nADPFUpdateTargetDuration(IntPtr sessionPtr, long targetDurationNanos);
         [DllImport(lib_name)] internal static extern void nADPFCloseSession(IntPtr sessionPtr);
+        [DllImport(lib_name)] internal static extern void nInstallCrashHandler([MarshalAs(UnmanagedType.LPUTF8Str)] string? logPath);
     }
 }