Echo Writes Code

windows_backtrace.cpp

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#include "crucible/core/backtrace.hpp"

#include "crucible/core/format.hpp"

#include <Windows.h>
#include <DbgHelp.h>

#include <cstddef>
#include <cstring>
#include <limits>
#include <mutex>
#include <optional>
#include <utility>

namespace crucible
{
	namespace
	{
		std::mutex backtrace_mutex;

		constexpr std::size_t MAXIMUM_SYMBOL_LENGTH { 1024 };

		struct SymSetOptionsWarden
		{
			std::optional<::DWORD> original_options { std::nullopt };

			~SymSetOptionsWarden();
		};

		SymSetOptionsWarden::~SymSetOptionsWarden()
		{
			if (original_options.has_value()) {
				::SymSetOptions(original_options.value());
			}
		}

		struct SymCleanupWarden
		{
			std::optional<::HANDLE> process_handle { std::nullopt };

			~SymCleanupWarden();
		};

		SymCleanupWarden::~SymCleanupWarden()
		{
			if (process_handle.has_value()) {
				::SymCleanup(process_handle.value());
			}
		}
	}

	auto backtrace() -> Backtrace_Result<Heap_Buffer<Stack_Frame>>
	{
		std::unique_lock<std::mutex> const backtrace_lock { backtrace_mutex };
		auto result { make_heap_buffer<Stack_Frame>() };

		::DWORD original_options { ::SymGetOptions() };
		::SymSetOptions(original_options | SYMOPT_DEFERRED_LOADS | SYMOPT_LOAD_LINES);
		SymSetOptionsWarden const sym_set_options_warden { original_options };

		// Not sure where to put this, but: ::GetCurrentProcess() returns INVALID_HANDLE_VALUE... ON PURPOSE!!!
		// MSDN: https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getcurrentprocess
		::HANDLE process_handle { ::GetCurrentProcess() };

		if (::SymInitialize(process_handle, nullptr, TRUE) != TRUE) {
			return make_failure<Backtrace_Error>(SymInitialize_Failed {});
		}

		SymCleanupWarden const sym_cleanup_warden { process_handle };

		::CONTEXT processor_context {};
		::RtlCaptureContext(&processor_context);

		::STACKFRAME64 stack_frame {};
		stack_frame.AddrPC.Offset = processor_context.Rip;
		stack_frame.AddrPC.Mode = ::AddrModeFlat;
		stack_frame.AddrFrame.Offset = processor_context.Rbp;
		stack_frame.AddrFrame.Mode = ::AddrModeFlat;
		stack_frame.AddrStack.Offset = processor_context.Rsp;
		stack_frame.AddrStack.Mode = ::AddrModeFlat;

		::DWORD unused32 { 0 };
		::DWORD64 unused64 { 0 };

		// BARK BARK BARK BARK BARK
		alignas(::IMAGEHLP_SYMBOL64) std::byte symbol_storage[sizeof(::IMAGEHLP_SYMBOL64) + MAXIMUM_SYMBOL_LENGTH];
		::IMAGEHLP_SYMBOL64 *symbol { new (&symbol_storage) ::IMAGEHLP_SYMBOL64 };

		do {
			::BOOL const have_next_frame = ::StackWalk64(
				IMAGE_FILE_MACHINE_AMD64,
				::GetCurrentProcess(),
				::GetCurrentThread(),
				&stack_frame,
				&processor_context,
				nullptr,
				::SymFunctionTableAccess64,
				::SymGetModuleBase64,
				nullptr
			);

			if (have_next_frame != TRUE) {
				Stack_Frame frame;
				frame.function = format_unsigned_hexadecimal(stack_frame.AddrPC.Offset);
				frame.details = "Failed to find stack frame";
				result.push(frame);
				break;
			}

			symbol->SizeOfStruct = sizeof(::IMAGEHLP_SYMBOL64);
			symbol->MaxNameLength = MAXIMUM_SYMBOL_LENGTH;

			::BOOL const have_next_symbol {
				::SymGetSymFromAddr64(
					process_handle,
					stack_frame.AddrPC.Offset,
					&unused64,
					symbol
				)
			};

			if (have_next_symbol != TRUE) {
				Stack_Frame frame;
				frame.function = format_unsigned_hexadecimal(stack_frame.AddrPC.Offset);
				frame.details = "Failed to find symbol";
				result.push(frame);
				break;
			}

			::IMAGEHLP_LINE64 line {};
			line.SizeOfStruct = sizeof(::IMAGEHLP_LINE64);

			::BOOL const have_next_line {
				::SymGetLineFromAddr64(
					process_handle,
					stack_frame.AddrPC.Offset,
					&unused32,
					&line
				)
			};

			if (have_next_line != TRUE) {
				Stack_Frame frame;
				frame.function = String { symbol->Name, std::strlen(symbol->Name) } + "()";
				frame.details = "Failed to find file and line";
				result.push(frame);
				continue;
			}

			CRUCIBLE_ASSERT_GE(line.LineNumber, 0u);
			CRUCIBLE_ASSERT_LE(static_cast<int>(line.LineNumber), std::numeric_limits<int>::max());

			String_View const file { line.FileName, std::strlen(line.FileName) };
			auto const relative_file { file.view().strip_prefix(CRUCIBLE_SOURCE_ROOT) };

			Stack_Frame frame;
			frame.function = String { symbol->Name, std::strlen(symbol->Name) } + "()";
			frame.location = relative_file + ":" + format_integral(line.LineNumber);
			result.push(frame);
		} while (stack_frame.AddrReturn.Offset != 0);

		return make_success(std::move(result));
	}
}