From 389bf89e2a105e808178590c0212afe361ee3667 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sun, 19 Nov 2023 11:07:40 +0100
Subject: [PATCH] Add `GetStackFrames` on Android

---
 .../Platform/Android/AndroidPlatform.cpp      | 68 +++++++++++++++++++
 .../Engine/Platform/Android/AndroidPlatform.h |  1 +
 2 files changed, 69 insertions(+)

diff --git a/Source/Engine/Platform/Android/AndroidPlatform.cpp b/Source/Engine/Platform/Android/AndroidPlatform.cpp
index c844ab81d..e71d4534a 100644
--- a/Source/Engine/Platform/Android/AndroidPlatform.cpp
+++ b/Source/Engine/Platform/Android/AndroidPlatform.cpp
@@ -51,6 +51,33 @@
 #include <android/window.h>
 #include <android/versioning.h>
 
+#if CRASH_LOG_ENABLE
+
+#include <unwind.h>
+#include <cxxabi.h>
+
+struct AndroidBacktraceState
+{
+    void** Current;
+    void** End;
+};
+
+_Unwind_Reason_Code AndroidUnwindCallback(struct _Unwind_Context* context, void* arg)
+{
+    AndroidBacktraceState* state = (AndroidBacktraceState*)arg;
+    uintptr_t pc = _Unwind_GetIP(context);
+    if (pc)
+    {
+        if (state->Current == state->End)
+            return _URC_END_OF_STACK;
+        else
+            *state->Current++ = reinterpret_cast<void*>(pc);
+    }
+    return _URC_NO_REASON;
+}
+
+#endif
+
 struct AndroidKeyEventType
 {
     uint32_t KeyCode;
@@ -1066,4 +1093,45 @@ void* AndroidPlatform::GetProcAddress(void* handle, const char* symbol)
     return dlsym(handle, symbol);
 }
 
+Array<AndroidPlatform::StackFrame> AndroidPlatform::GetStackFrames(int32 skipCount, int32 maxDepth, void* context)
+{
+    Array<StackFrame> result;
+#if CRASH_LOG_ENABLE
+    // Reference: https://stackoverflow.com/questions/8115192/android-ndk-getting-the-backtrace
+    void* callstack[120];
+    skipCount = Math::Min<int32>(skipCount, ARRAY_COUNT(callstack));
+    int32 maxCount = Math::Min<int32>(ARRAY_COUNT(callstack), skipCount + maxDepth);
+    AndroidBacktraceState state;
+    state.Current = callstack;
+    state.End = callstack + maxCount;
+    _Unwind_Backtrace(AndroidUnwindCallback, &state);
+    int32 count = (int32)(state.Current - callstack);
+    int32 useCount = count - skipCount;
+    if (useCount > 0)
+    {
+        result.Resize(useCount);
+        for (int32 i = 0; i < useCount; i++)
+        {
+            StackFrame& frame = result[i];
+            frame.ProgramCounter = callstack[skipCount + i];
+            frame.ModuleName[0] = 0;
+            frame.FileName[0] = 0;
+            frame.LineNumber = 0;
+            Dl_info info;
+            const char* symbol = "";
+            if (dladdr(frame.ProgramCounter, &info) && info.dli_sname) 
+                symbol = info.dli_sname;
+            int status = 0; 
+            char* demangled = __cxxabiv1::__cxa_demangle(symbol, 0, 0, &status); 
+            int32 nameLen = Math::Min<int32>(StringUtils::Length(demangled), ARRAY_COUNT(frame.FunctionName) - 1);
+            Platform::MemoryCopy(frame.FunctionName, demangled, nameLen);
+            frame.FunctionName[nameLen] = 0;
+            if (demangled)
+                free(demangled);
+        }
+    }
+#endif
+    return result;
+}
+
 #endif
diff --git a/Source/Engine/Platform/Android/AndroidPlatform.h b/Source/Engine/Platform/Android/AndroidPlatform.h
index 07e72cac4..577da45de 100644
--- a/Source/Engine/Platform/Android/AndroidPlatform.h
+++ b/Source/Engine/Platform/Android/AndroidPlatform.h
@@ -132,6 +132,7 @@ public:
     static void* LoadLibrary(const Char* filename);
     static void FreeLibrary(void* handle);
     static void* GetProcAddress(void* handle, const char* symbol);
+    static Array<StackFrame, HeapAllocation> GetStackFrames(int32 skipCount = 0, int32 maxDepth = 60, void* context = nullptr);
 };
 
 #endif