From 20b0337e0a8e8f6a3b84976dca17d2dcbc91e910 Mon Sep 17 00:00:00 2001
From: Cory McWilliams <cory@unprompted.com>
Date: Wed, 29 Mar 2023 22:25:17 +0000
Subject: [PATCH] Hook up backtraces on android.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@4251 ed5197a5-7fde-0310-b194-c3ffbd925b24
---
 src/util.js.c | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/src/util.js.c b/src/util.js.c
index 31f0b414..88a7b8eb 100644
--- a/src/util.js.c
+++ b/src/util.js.c
@@ -14,11 +14,11 @@
 
 #include <string.h>
 
-#ifndef _WIN32
-#ifndef __ANDROID__
+#if defined(__ANDROID__)
+#include <unwind.h>
+#elif !defined(_WIN32)
 #include <execinfo.h>
 #endif
-#endif
 
 static JSValue _util_utf8_encode(JSContext* context, JSValueConst this_val, int argc, JSValueConst* argv)
 {
@@ -469,13 +469,41 @@ const char* tf_util_backtrace_string()
 	return tf_util_backtrace_to_string(buffer, count);
 }
 
+#if defined(__ANDROID__)
+typedef struct _android_backtrace_t
+{
+	void** current;
+	void** end;
+} android_backtrace_t;
+
+static _Unwind_Reason_Code _android_unwind_callback(struct _Unwind_Context* context, void* arg)
+{
+	android_backtrace_t* state = arg;
+	uintptr_t pc = _Unwind_GetIP(context);
+	if (pc)
+	{
+		if (state->current == state->end)
+		{
+			return _URC_END_OF_STACK;
+		}
+		else
+		{
+			*state->current++ = (void*)pc;
+		}
+	}
+	return _URC_NO_REASON;
+}
+#endif
+
 int tf_util_backtrace(void** buffer, int count)
 {
 #ifdef _WIN32
 	return CaptureStackBackTrace(0, count, buffer, NULL);
-#elif !defined(__ANDROID__)
-	return backtrace(buffer, count);
+#elif defined(__ANDROID__)
+	android_backtrace_t state = { .current = buffer, .end = buffer + count };
+	_Unwind_Backtrace(_android_unwind_callback, &state);
+	return state.current - buffer;
 #else
-	return 0;
+	return backtrace(buffer, count);
 #endif
 }