From a467392cbd8a2b59ce6ac841d52d33df1b0cc31f Mon Sep 17 00:00:00 2001
From: Peter Johnson <johnson.peter@gmail.com>
Date: Fri, 21 Jan 2022 17:22:41 -0800
Subject: [PATCH] [wpiutil] StackTrace: Add ability to override default
 implementation (#3951)

---
 wpiutil/src/main/native/cpp/StackTraceWrap.cpp | 18 ++++++++++++++++++
 .../src/main/native/include/wpi/StackTrace.h   | 14 ++++++++++++++
 wpiutil/src/main/native/unix/StackTrace.cpp    |  2 +-
 wpiutil/src/main/native/windows/StackTrace.cpp |  2 +-
 4 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 wpiutil/src/main/native/cpp/StackTraceWrap.cpp

diff --git a/wpiutil/src/main/native/cpp/StackTraceWrap.cpp b/wpiutil/src/main/native/cpp/StackTraceWrap.cpp
new file mode 100644
index 0000000000..37a83f7ef0
--- /dev/null
+++ b/wpiutil/src/main/native/cpp/StackTraceWrap.cpp
@@ -0,0 +1,18 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <atomic>
+
+#include "wpi/StackTrace.h"
+
+static std::atomic<std::string (*)(int offset)> gStackTraceImpl{
+    wpi::GetStackTraceDefault};
+
+std::string wpi::GetStackTrace(int offset) {
+  return (gStackTraceImpl.load())(offset);
+}
+
+void wpi::SetGetStackTraceImpl(std::string (*func)(int offset)) {
+  gStackTraceImpl = func ? func : wpi::GetStackTraceDefault;
+}
diff --git a/wpiutil/src/main/native/include/wpi/StackTrace.h b/wpiutil/src/main/native/include/wpi/StackTrace.h
index f9ee989d41..44e0b21d7b 100644
--- a/wpiutil/src/main/native/include/wpi/StackTrace.h
+++ b/wpiutil/src/main/native/include/wpi/StackTrace.h
@@ -16,6 +16,20 @@ namespace wpi {
  */
 std::string GetStackTrace(int offset);
 
+/**
+ * The default implementation used for GetStackTrace().
+ *
+ * @param offset The number of symbols at the top of the stack to ignore
+ */
+std::string GetStackTraceDefault(int offset);
+
+/**
+ * Set the implementation used by GetStackTrace().
+ *
+ * @param func Function called by GetStackTrace().
+ */
+void SetGetStackTraceImpl(std::string (*func)(int offset));
+
 }  // namespace wpi
 
 #endif  // WPIUTIL_WPI_STACKTRACE_H_
diff --git a/wpiutil/src/main/native/unix/StackTrace.cpp b/wpiutil/src/main/native/unix/StackTrace.cpp
index 598c9da099..3b6606533b 100644
--- a/wpiutil/src/main/native/unix/StackTrace.cpp
+++ b/wpiutil/src/main/native/unix/StackTrace.cpp
@@ -13,7 +13,7 @@
 
 namespace wpi {
 
-std::string GetStackTrace(int offset) {
+std::string GetStackTraceDefault(int offset) {
   void* stackTrace[128];
   int stackSize = backtrace(stackTrace, 128);
   char** mangledSymbols = backtrace_symbols(stackTrace, stackSize);
diff --git a/wpiutil/src/main/native/windows/StackTrace.cpp b/wpiutil/src/main/native/windows/StackTrace.cpp
index 3e3ccfaeb8..bab5f83511 100644
--- a/wpiutil/src/main/native/windows/StackTrace.cpp
+++ b/wpiutil/src/main/native/windows/StackTrace.cpp
@@ -32,7 +32,7 @@ void StackTraceWalker::OnOutput(LPCTSTR szText) {
 
 namespace wpi {
 
-std::string GetStackTrace(int offset) {
+std::string GetStackTraceDefault(int offset) {
   // TODO: implement offset
   std::string output;
   StackTraceWalker walker(output);