From a7404a88bdbaac01f4c78db4c502ff5485d8e78c Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Tue, 5 Nov 2019 17:57:58 +0000
Subject: [PATCH] OSX: Remove use of sigaltstack

---
 config.lib                     | 27 ------------------------
 src/os/macosx/crashlog_osx.cpp | 38 ----------------------------------
 2 files changed, 65 deletions(-)

diff --git a/config.lib b/config.lib
index 64f1faec1b..7df1964ae8 100644
--- a/config.lib
+++ b/config.lib
@@ -1983,33 +1983,6 @@ EOL
 			log 1 "checking ucontext... found"
 			CFLAGS="$CFLAGS -DWITH_UCONTEXT"
 		fi
-
-		log 2 "executing $cc_host $CFLAGS $CFLAGS_ENV $LDFLAGS $LDFLAGS_ENV $STATIC_FLAGS -o tmp.config.sigaltstack -x c++ - -ldl"
-		"$cc_host" $CFLAGS $CFLAGS_ENV $LDFLAGS $LDFLAGS_ENV $STATIC_FLAGS -o tmp.config.sigaltstack -x c++ - -ldl 2> /dev/null << EOL
-			#include <signal.h>
-			#include <stdlib.h>
-			#include <pthread.h>
-			int main() {
-				pthread_t self = pthread_self();
-				void *stacktop = pthread_get_stackaddr_np(self);
-				size_t stack_size = pthread_get_stacksize_np(self);
-				stack_t ss;
-				ss.ss_sp = calloc(SIGSTKSZ, 1);
-				ss.ss_size = SIGSTKSZ;
-				ss.ss_flags = 0;
-				sigaltstack(&ss, NULL);
-				return 0;
-			}
-EOL
-		ret=$?
-		rm -f tmp.config.sigaltstack
-		log 2 "  exit code $ret"
-		if [ $ret -ne 0 ]; then
-			log 1 "checking sigaltstack... no"
-		else
-			log 1 "checking sigaltstack... found"
-			CFLAGS="$CFLAGS -DWITH_SIGALTSTACK"
-		fi
 	fi
 
 	if [ "$os" = "HAIKU" ]; then
diff --git a/src/os/macosx/crashlog_osx.cpp b/src/os/macosx/crashlog_osx.cpp
index 688464f882..9b423a0625 100644
--- a/src/os/macosx/crashlog_osx.cpp
+++ b/src/os/macosx/crashlog_osx.cpp
@@ -27,9 +27,6 @@
 #ifdef WITH_UCONTEXT
 #include <sys/ucontext.h>
 #endif
-#if defined(WITH_SIGALTSTACK) && defined(WITH_UCONTEXT)
-#include <pthread.h>
-#endif
 
 #include "../../safeguards.h"
 
@@ -218,30 +215,6 @@ class CrashLogOSX : public CrashLog {
 #if defined(__ppc__) || defined(__ppc64__)
 		/* Apple says __builtin_frame_address can be broken on PPC. */
 		__asm__ volatile("mr %0, r1" : "=r" (frame));
-#elif defined(WITH_SIGALTSTACK) && defined(WITH_UCONTEXT) && (defined(__x86_64__) || defined(__i386))
-		if (this->signal_instruction_ptr_valid) {
-			print_frame(this->signal_instruction_ptr);
-			i++;
-		}
-
-		pthread_t self = pthread_self();
-		char *stacktop = (char *) pthread_get_stackaddr_np(self);
-		char *stackbot = stacktop - pthread_get_stacksize_np(self);
-		stacktop -= 2 * sizeof(void *);
-
-		ucontext_t *ucontext = static_cast<ucontext_t *>(context);
-#if defined(__x86_64__)
-		void **bp = (void **) ucontext->uc_mcontext->__ss.__rbp;
-		void **sp = (void **) ucontext->uc_mcontext->__ss.__rsp;
-#else
-		void **bp = (void **) ucontext->uc_mcontext->__ss.__ebp;
-		void **sp = (void **) ucontext->uc_mcontext->__ss.__esp;
-#endif
-		if (IS_ALIGNED(bp) && reinterpret_cast<uintptr_t>(bp) >= reinterpret_cast<uintptr_t>(sp) && reinterpret_cast<uintptr_t>(bp) >= reinterpret_cast<uintptr_t>(stackbot) && reinterpret_cast<uintptr_t>(bp) <= reinterpret_cast<uintptr_t>(stacktop)) {
-			frame = bp;
-		} else {
-			frame = nullptr;
-		}
 #else
 		frame = (void **)__builtin_frame_address(0);
 #endif
@@ -495,21 +468,10 @@ void CDECL HandleCrash(int signum, siginfo_t *si, void *context)
 
 /* static */ void CrashLog::InitialiseCrashLog()
 {
-#if defined(WITH_SIGALTSTACK) && defined(WITH_UCONTEXT)
-	const size_t stack_size = max<size_t>(SIGSTKSZ, 512*1024);
-	stack_t ss;
-	ss.ss_sp = CallocT<byte>(stack_size);
-	ss.ss_size = stack_size;
-	ss.ss_flags = 0;
-	sigaltstack(&ss, nullptr);
-#endif
 	for (const int *i = _signals_to_handle; i != endof(_signals_to_handle); i++) {
 		struct sigaction sa;
 		memset(&sa, 0, sizeof(sa));
 		sa.sa_flags = SA_SIGINFO | SA_RESTART;
-#if defined(WITH_SIGALTSTACK) && defined(WITH_UCONTEXT)
-		sa.sa_flags |= SA_ONSTACK;
-#endif
 		sigemptyset(&sa.sa_mask);
 		sa.sa_sigaction = HandleCrash;
 		sigaction(*i, &sa, nullptr);