From 43792b8a13289f9cee247cf6ff1577a55c31888b Mon Sep 17 00:00:00 2001
From: Sergiu Deitsch <sergiu.deitsch@gmail.com>
Date: Fri, 29 Dec 2023 23:18:08 +0100
Subject: [PATCH] rework (lib)unwind integration

Allow to switch between the two backends.
---
 CMakeLists.txt        | 41 ++++++++++++++++++++++++++++++++++++-----
 bazel/glog.bzl        |  3 +--
 src/config.h.cmake.in | 11 ++++-------
 src/utilities.h       |  6 +++---
 4 files changed, 44 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e76fb1486..f7f08fe0f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,7 +40,9 @@ option (WITH_GTEST "Use Google Test" ON)
 option (WITH_PKGCONFIG "Enable pkg-config support" ON)
 option (WITH_SYMBOLIZE "Enable symbolize module" ON)
 option (WITH_THREADS "Enable multithreading support" ON)
-option (WITH_UNWIND "Enable libunwind support" ON)
+
+set (WITH_UNWIND libunwind CACHE STRING "unwind driver")
+set_property (CACHE WITH_UNWIND PROPERTY STRINGS none unwind libunwind)
 
 cmake_dependent_option (WITH_GMOCK "Use Google Mock" ON WITH_GTEST OFF)
 cmake_dependent_option (WITH_TLS "Enable Thread Local Storage (TLS) support" ON WITH_THREADS OFF)
@@ -48,9 +50,9 @@ cmake_dependent_option (WITH_TLS "Enable Thread Local Storage (TLS) support" ON
 set (WITH_FUZZING none CACHE STRING "Fuzzing engine")
 set_property (CACHE WITH_FUZZING PROPERTY STRINGS none libfuzzer ossfuzz)
 
-if (NOT WITH_UNWIND)
+if (WITH_UNWIND STREQUAL none)
   set (CMAKE_DISABLE_FIND_PACKAGE_Unwind ON)
-endif (NOT WITH_UNWIND)
+endif (WITH_UNWIND STREQUAL none)
 
 if (NOT WITH_GTEST)
   set (CMAKE_DISABLE_FIND_PACKAGE_GTest ON)
@@ -91,13 +93,42 @@ find_package (Threads)
 find_package (Unwind)
 
 if (Unwind_FOUND)
-  set (HAVE_LIB_UNWIND 1)
-else (Unwind_FOUND)
+  cmake_push_check_state (RESET)
+  set (CMAKE_REQUIRED_LIBRARIES unwind::unwind)
+
   # Check whether linking actually succeeds. ARM toolchains of LLVM unwind
   # implementation do not necessarily provide the _Unwind_Backtrace function
   # which causes the previous check to succeed but the linking to fail.
   check_cxx_symbol_exists (_Unwind_Backtrace unwind.h HAVE__UNWIND_BACKTRACE)
   check_cxx_symbol_exists (_Unwind_GetIP unwind.h HAVE__UNWIND_GETIP)
+
+  check_cxx_symbol_exists (unw_get_reg libunwind.h HAVE_UNW_GET_REG)
+  check_cxx_symbol_exists (unw_getcontext libunwind.h HAVE_UNW_GETCONTEXT)
+  check_cxx_symbol_exists (unw_init_local libunwind.h HAVE_UNW_INIT_LOCAL)
+  check_cxx_symbol_exists (unw_step libunwind.h HAVE_UNW_STEP)
+
+  if (HAVE__UNWIND_BACKTRACE AND HAVE__UNWIND_GETIP)
+    set (_HAVE_UNWIND 1)
+  endif (HAVE__UNWIND_BACKTRACE AND HAVE__UNWIND_GETIP)
+
+  if (HAVE_UNW_GET_REG AND HAVE_UNW_GETCONTEXT AND HAVE_UNW_INIT_LOCAL AND HAVE_UNW_STEP)
+    set (_HAVE_LIBUNWIND 1)
+  endif (HAVE_UNW_GET_REG AND HAVE_UNW_GETCONTEXT AND HAVE_UNW_INIT_LOCAL AND HAVE_UNW_STEP)
+
+  if (WITH_UNWIND STREQUAL unwind)
+    if (_HAVE_UNWIND)
+      set (HAVE_UNWIND 1)
+    endif (_HAVE_UNWIND)
+  elseif (WITH_UNWIND STREQUAL libunwind)
+    if (_HAVE_LIBUNWIND)
+      set (HAVE_LIBUNWIND 1)
+    endif (_HAVE_LIBUNWIND)
+  endif (WITH_UNWIND STREQUAL unwind)
+
+  unset (_HAVE_LIBUNWIND)
+  unset (_HAVE_UNWIND)
+
+  cmake_pop_check_state ()
 endif (Unwind_FOUND)
 
 check_include_file_cxx (dlfcn.h HAVE_DLFCN_H)
diff --git a/bazel/glog.bzl b/bazel/glog.bzl
index 8234d0f50..b92473b36 100644
--- a/bazel/glog.bzl
+++ b/bazel/glog.bzl
@@ -73,8 +73,7 @@ def glog_library(namespace = "google", with_gflags = 1, **kwargs):
         "-DHAVE_SYS_UTSNAME_H",
         # For src/utilities.cc.
         "-DHAVE_SYS_TIME_H",
-        "-DHAVE__UNWIND_BACKTRACE",
-        "-DHAVE__UNWIND_GETIP",
+        "-DHAVE_UNWIND",
         # Enable dumping stacktrace upon sigaction.
         "-DHAVE_SIGACTION",
         # For logging.cc.
diff --git a/src/config.h.cmake.in b/src/config.h.cmake.in
index 70440971d..752d76648 100644
--- a/src/config.h.cmake.in
+++ b/src/config.h.cmake.in
@@ -37,9 +37,6 @@
 /* define if you have dbghelp library */
 #cmakedefine HAVE_DBGHELP
 
-/* define if you have libunwind */
-#cmakedefine HAVE_LIB_UNWIND
-
 /* Define to 1 if you have the <memory.h> header file. */
 #cmakedefine HAVE_MEMORY_H
 
@@ -103,11 +100,11 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine HAVE_UNISTD_H ${HAVE_UNISTD_H}
 
-/* Define if you linking to _Unwind_Backtrace is possible. */
-#cmakedefine HAVE__UNWIND_BACKTRACE
+/* define if you have unwind */
+#cmakedefine HAVE_UNWIND
 
-/* Define if you linking to _Unwind_GetIP is possible. */
-#cmakedefine HAVE__UNWIND_GETIP
+/* define if you have libunwind */
+#cmakedefine HAVE_LIBUNWIND
 
 /* define if your compiler has __attribute__ */
 #cmakedefine HAVE___ATTRIBUTE__
diff --git a/src/utilities.h b/src/utilities.h
index ae34d8d4c..e06a308e8 100644
--- a/src/utilities.h
+++ b/src/utilities.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2008, Google Inc.
+// Copyright (c) 2023, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
@@ -85,9 +85,9 @@
 // correctly when GetStackTrace() is called with max_depth == 0.
 // Some code may do that.
 
-#if defined(HAVE_LIB_UNWIND)
+#if defined(HAVE_LIBUNWIND)
 # define STACKTRACE_H "stacktrace_libunwind-inl.h"
-#elif defined(HAVE__UNWIND_BACKTRACE) && defined(HAVE__UNWIND_GETIP)
+#elif defined(HAVE_UNWIND)
 # define STACKTRACE_H "stacktrace_unwind-inl.h"
 #elif !defined(NO_FRAME_POINTER)
 # if defined(__i386__) && __GNUC__ >= 2