Linux crashlog: Use sigaction to get more info on fatal signals.

config.lib

@@ -1689,6 +1689,34 @@ EOL
 				CFLAGS="$CFLAGS -g1"
 			fi
 		fi
+
+		log 2 "executing $cc_host $CFLAGS $LDFLAGS $STATIC_FLAGS -o tmp.config.sigaction -x c++ - -ldl"
+		"$cc_host" $CFLAGS $LDFLAGS $STATIC_FLAGS -o tmp.config.sigaction -x c++ - -ldl 2> /dev/null << EOL
+			#include <signal.h>
+			void *addr;
+			int code;
+			void handler(int sig, siginfo_t *si, void *context) {
+				addr = si->si_addr;
+				code = si->si_code;
+			}
+			int main() {
+				struct sigaction sa;
+				sa.sa_flags = SA_SIGINFO;
+				sigemptyset(&sa.sa_mask);
+				sa.sa_sigaction = handler;
+				sigaction(SIGSEGV, &sa, 0);
+				return 0;
+			}
+EOL
+		ret=$?
+		rm -f tmp.config.sigaction
+		log 2 "  exit code $ret"
+		if [ $ret -ne 0 ]; then
+			log 1 "checking sigaction... no"
+		else
+			log 1 "checking sigaction... found"
+			CFLAGS="$CFLAGS -DWITH_SIGACTION"
+		fi
 	fi
 
 	if [ "$os" = "MINGW" ]; then

src/os/unix/crashlog_unix.cpp

@@ -78,6 +78,9 @@ static void LogStacktraceSigSegvHandler(int  sig)
 class CrashLogUnix : public CrashLog {
 	/** Signal that has been thrown. */
 	int signum;
+#ifdef WITH_SIGACTION
+	siginfo_t *si;
+#endif
 
 	/* virtual */ char *LogOSVersion(char *buffer, const char *last) const
 	{
@@ -101,14 +104,29 @@ class CrashLogUnix : public CrashLog {
 
 	/* virtual */ char *LogError(char *buffer, const char *last, const char *message) const
 	{
-		return buffer + seprintf(buffer, last,
+		buffer += seprintf(buffer, last,
 				"Crash reason:\n"
-				" Signal:  %s (%d)\n"
+				" Signal:  %s (%d)\n",
-				" Message: %s\n\n",
 				strsignal(this->signum),
-				this->signum,
+				this->signum);
+#ifdef WITH_SIGACTION
+		if (this->si) {
+			buffer += seprintf(buffer, last,
+					"          si_code: %d\n",
+					this->si->si_code);
+			if (this->signum != SIGABRT) {
+				buffer += seprintf(buffer, last,
+						"          fault address: %p\n",
+						this->si->si_addr);
+			}
+		}
+#endif
+		buffer += seprintf(buffer, last,
+				" Message: %s\n\n",
 				message == NULL ? "<none>" : message
 		);
+
+		return buffer;
 	}
 
 #if defined(SUNOS)
@@ -378,10 +396,17 @@ public:
 	 * A crash log is always generated by signal.
 	 * @param signum the signal that was caused by the crash.
 	 */
+#ifdef WITH_SIGACTION
+	CrashLogUnix(int signum, siginfo_t *si) :
+		signum(signum), si(si)
+	{
+	}
+#else
 	CrashLogUnix(int signum) :
 		signum(signum)
 	{
 	}
+#endif
 };
 
 /** The signals we want our crash handler to handle. */
@@ -392,7 +417,11 @@ static const int _signals_to_handle[] = { SIGSEGV, SIGABRT, SIGFPE, SIGBUS, SIGI
  * @note Not static so it shows up in the backtrace.
  * @param signum the signal that caused us to crash.
  */
+#ifdef WITH_SIGACTION
+static void CDECL HandleCrash(int signum, siginfo_t *si, void *context)
+#else
 static void CDECL HandleCrash(int signum)
+#endif
 {
 	/* Disable all handling of signals by us, so we don't go into infinite loops. */
 	for (const int *i = _signals_to_handle; i != endof(_signals_to_handle); i++) {
@@ -412,7 +441,11 @@ static void CDECL HandleCrash(int signum)
 		abort();
 	}
 
+#ifdef WITH_SIGACTION
+	CrashLogUnix log(signum, si);
+#else
 	CrashLogUnix log(signum);
+#endif
 	log.MakeCrashLog();
 
 	CrashLog::AfterCrashLogCleanup();
@@ -422,6 +455,15 @@ static void CDECL HandleCrash(int signum)
 /* static */ void CrashLog::InitialiseCrashLog()
 {
 	for (const int *i = _signals_to_handle; i != endof(_signals_to_handle); i++) {
+#ifdef WITH_SIGACTION
+		struct sigaction sa;
+		memset(&sa, 0, sizeof(sa));
+		sa.sa_flags = SA_SIGINFO | SA_RESTART;
+		sigemptyset(&sa.sa_mask);
+		sa.sa_sigaction = HandleCrash;
+		sigaction(*i, &sa, NULL);
+#else
 		signal(*i, HandleCrash);
+#endif
 	}
 }

src/saveload/afterload.cpp

@@ -302,12 +302,20 @@ static void InitializeWindowsAndCaches()
 	BuildOwnerLegend();
 }
 
+#ifdef WITH_SIGACTION
+static struct sigaction _prev_segfault;
+static struct sigaction _prev_abort;
+static struct sigaction _prev_fpe;
+
+static void CDECL HandleSavegameLoadCrash(int signum, siginfo_t *si, void *context);
+#else
 typedef void (CDECL *SignalHandlerPointer)(int);
 static SignalHandlerPointer _prev_segfault = NULL;
 static SignalHandlerPointer _prev_abort    = NULL;
 static SignalHandlerPointer _prev_fpe      = NULL;
 
 static void CDECL HandleSavegameLoadCrash(int signum);
+#endif
 
 /**
  * Replaces signal handlers of SIGSEGV and SIGABRT
@@ -315,9 +323,20 @@ static void CDECL HandleSavegameLoadCrash(int signum);
  */
 static void SetSignalHandlers()
 {
+#ifdef WITH_SIGACTION
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_flags = SA_SIGINFO | SA_RESTART;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_sigaction = HandleSavegameLoadCrash;
+	sigaction(SIGSEGV, &sa, &_prev_segfault);
+	sigaction(SIGABRT, &sa, &_prev_abort);
+	sigaction(SIGFPE,  &sa, &_prev_fpe);
+#else
 	_prev_segfault = signal(SIGSEGV, HandleSavegameLoadCrash);
 	_prev_abort    = signal(SIGABRT, HandleSavegameLoadCrash);
 	_prev_fpe      = signal(SIGFPE,  HandleSavegameLoadCrash);
+#endif
 }
 
 /**
@@ -325,9 +344,15 @@ static void SetSignalHandlers()
  */
 static void ResetSignalHandlers()
 {
+#ifdef WITH_SIGACTION
+	sigaction(SIGSEGV, &_prev_segfault, NULL);
+	sigaction(SIGABRT, &_prev_abort, NULL);
+	sigaction(SIGFPE,  &_prev_fpe, NULL);
+#else
 	signal(SIGSEGV, _prev_segfault);
 	signal(SIGABRT, _prev_abort);
 	signal(SIGFPE,  _prev_fpe);
+#endif
 }
 
 /**
@@ -367,7 +392,11 @@ bool SaveloadCrashWithMissingNewGRFs()
  * NewGRFs that are required by the savegame.
  * @param signum received signal
  */
+#ifdef WITH_SIGACTION
+static void CDECL HandleSavegameLoadCrash(int signum, siginfo_t *si, void *context)
+#else
 static void CDECL HandleSavegameLoadCrash(int signum)
+#endif
 {
 	ResetSignalHandlers();
 
@@ -414,14 +443,27 @@ static void CDECL HandleSavegameLoadCrash(int signum)
 
 	ShowInfo(buffer);
 
+#ifdef WITH_SIGACTION
+	struct sigaction call;
+#else
 	SignalHandlerPointer call = NULL;
+#endif
 	switch (signum) {
 		case SIGSEGV: call = _prev_segfault; break;
 		case SIGABRT: call = _prev_abort; break;
 		case SIGFPE:  call = _prev_fpe; break;
 		default: NOT_REACHED();
 	}
+#ifdef WITH_SIGACTION
+	if (call.sa_flags & SA_SIGINFO) {
+		if (call.sa_sigaction != NULL) call.sa_sigaction(signum, si, context);
+	} else {
+		if (call.sa_handler != NULL) call.sa_handler(signum);
+	}
+#else
 	if (call != NULL) call(signum);
+#endif
+
 }
 
 /**