Implemented stacktrace collection for Windows.

source/mijin/debug/stacktrace.cpp

@@ -5,14 +5,22 @@
 #include <string>
 #include "../detect.hpp"
 
-#if MIJIN_COMPILER == MIJIN_COMPILER_CLANG || MIJIN_COMPILER == MIJIN_COMPILER_GCC
+#if MIJIN_TARGET_OS != MIJIN_OS_WINDOWS && (MIJIN_COMPILER == MIJIN_COMPILER_CLANG || MIJIN_COMPILER == MIJIN_COMPILER_GCC)
 #define MIJIN_USE_LIBBACKTRACE 1
 #else
 #define MIJIN_USE_LIBBACKTRACE 0
 #endif
 
 #if MIJIN_USE_LIBBACKTRACE
-#include <backtrace.h>
+    #include <backtrace.h>
+#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+    #include <array>
+    #include <cstddef>
+    #include <mutex>
+    #include <Windows.h>
+    #include <DbgHelp.h>
+    #include "../util/winundef.hpp"
+    #pragma comment(lib, "dbghelp")
 #endif
 
 
@@ -32,11 +40,15 @@ namespace
 // internal types
 //
 
+#if MIJIN_USE_LIBBACKTRACE
 struct BacktraceData
 {
     std::optional<std::string> error;
     std::vector<Stackframe> stackframes;
 };
+#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+HANDLE gProcessHandle = nullptr;
+#endif
 
 //
 // internal variables
@@ -44,6 +56,11 @@ struct BacktraceData
 
 thread_local Optional<Stacktrace> gCurrentExceptionStackTrace;
 
+#if MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+std::mutex gDbgHelpMutex;
+bool gDbgHelpInitCalled = false;
+#endif
+
 //
 // internal functions
 //
@@ -68,6 +85,49 @@ void backtraceErrorCallback(void* data, const char* msg, int /* errnum */)
 }
 
 thread_local backtrace_state* gBacktraceState = nullptr;
+#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+void cleanupDbgHelp() MIJIN_NOEXCEPT
+{
+    if (!SymCleanup(gProcessHandle))
+    {
+        [[maybe_unused]] const DWORD error = GetLastError();
+        MIJIN_ERROR("Error cleaning up DbgHelp.");
+    }
+}
+
+[[nodiscard]]
+bool initDbgHelp() MIJIN_NOEXCEPT
+{
+    if (gDbgHelpInitCalled)
+    {
+        return gProcessHandle != nullptr; // if init was successful, process handle is not null
+    }
+    gDbgHelpInitCalled = true;
+
+    SymSetOptions(SYMOPT_UNDNAME | SYMOPT_DEFERRED_LOADS);
+
+    HANDLE hCurrentProcess = GetCurrentProcess();
+    HANDLE hCopy = nullptr;
+    if (!DuplicateHandle(hCurrentProcess, hCurrentProcess, hCurrentProcess, &hCopy, 0, FALSE, DUPLICATE_SAME_ACCESS))
+    {
+        [[maybe_unused]] const DWORD error = GetLastError();
+        MIJIN_ERROR("Error duplicating process handle.");
+        return false;
+    }
+    if (!SymInitialize(hCopy, nullptr, true))
+    {
+        [[maybe_unused]] const DWORD error = GetLastError();
+        MIJIN_ERROR("Error initializing DbHelp.");
+        return false;
+    }
+
+    const int result = std::atexit(&cleanupDbgHelp);
+    MIJIN_ASSERT(result == 0, "Error registering DbgHelp cleanup handler.");
+
+    // only copy in the end so we can still figure out if initialization was successful
+    gProcessHandle = hCopy;
+    return true;
+}
 #endif // MIJIN_USE_LIBBACKTRACE
 } // namespace
 
@@ -98,7 +158,85 @@ Result<Stacktrace> captureStacktrace(unsigned skipFrames) MIJIN_NOEXCEPT
     }
 
     return Stacktrace(std::move(btData.stackframes));
-#else // MIJIN_USE_LIBBACKTRACE
+#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+    if (!initDbgHelp())
+    {
+        return ResultError("error initializing DbgHelp");
+    }
+
+    const HANDLE hThread = GetCurrentThread();
+
+    CONTEXT context;
+    RtlCaptureContext(&context);
+
+    STACKFRAME64 stackFrame = {
+        .AddrPC = {
+            .Offset = context.Rip,
+            .Mode = AddrModeFlat
+        },
+        .AddrFrame = {
+            .Offset = context.Rbp,
+            .Mode = AddrModeFlat
+        },
+        .AddrStack = {
+            .Offset = context.Rsp,
+            .Mode = AddrModeFlat
+        }
+    };
+
+    ++skipFrames; // always skip the first frame (the current function)
+
+    // for symbol info
+    DWORD64 displacement64 = 0;
+    static constexpr std::size_t SYMBOL_BUFFER_SIZE = sizeof(SYMBOL_INFO) + (MAX_SYM_NAME * sizeof(char));
+    std::array<std::byte, SYMBOL_BUFFER_SIZE> symbolBuffer alignas(SYMBOL_INFO);
+    SYMBOL_INFO& symbolInfo = *std::bit_cast<SYMBOL_INFO*>(symbolBuffer.data());
+    symbolInfo.SizeOfStruct = sizeof(SYMBOL_BUFFER_SIZE);
+    symbolInfo.MaxNameLen = MAX_SYM_NAME;
+
+    // for file and line info
+    DWORD displacement = 0;
+    IMAGEHLP_LINE64 line64;
+    line64.SizeOfStruct = sizeof(IMAGEHLP_LINE64);
+
+    std::vector<Stackframe> stackframes;
+    while (StackWalk64(
+            /* MachineType                = */ IMAGE_FILE_MACHINE_AMD64,
+            /* hProcess                   = */ gProcessHandle,
+            /* hThread                    = */ hThread,
+            /* StackFrame                 = */ &stackFrame,
+            /* ContextRecord              = */ &context,
+            /* ReadMemoryRoutine          = */ nullptr,
+            /* FunctionTableAccessRoutine = */ &SymFunctionTableAccess64,
+            /* GetModuleBaseRoutine       = */ &SymGetModuleBase64,
+            /* TranslateAddress           = */ nullptr
+        ))
+    {
+        if (skipFrames > 0)
+        {
+            --skipFrames;
+            continue;
+        }
+        Stackframe& frame = stackframes.emplace_back();
+        const DWORD64 baseAddress = SymGetModuleBase64(gProcessHandle, stackFrame.AddrPC.Offset);
+        const DWORD64 relativeAddress = stackFrame.AddrPC.Offset - baseAddress;
+
+        frame.address = std::bit_cast<void*>(relativeAddress);
+
+        if (SymFromAddr(gProcessHandle, stackFrame.AddrPC.Offset, &displacement64, &symbolInfo))
+        {
+            frame.function = symbolInfo.Name;
+        }
+
+        if (SymGetLineFromAddr64(gProcessHandle, stackFrame.AddrPC.Offset, &displacement, &line64))
+        {
+            frame.filename = line64.FileName;
+            frame.lineNumber = static_cast<int>(line64.LineNumber);
+        }
+    }
+
+    return Stacktrace(std::move(stackframes));
+#else // MIJIN_USE_LIBBACKTRACE || (MIJIN_TARGET_OS == MIJIN_OS_WINDOWS)
 	(void) skipFrames;
 	return ResultError("not implemented");
 #endif // MIJIN_USE_LIBBACKTRACE