lem: unbreak build against plain Lua 5.1

3 files changed, 28 insertions, 0 deletions

diff --git a/bin/lem.c b/bin/lem.c
index 17bc15f..67789f5 100644
--- a/bin/lem.c
+++ b/bin/lem.c
@@ -195,10 +195,30 @@ lem_queue(lua_State *T, int nargs)
 static void
 thread_error(lua_State *T)
 {
+#ifdef HAVE_TRACEBACK
 	const char *msg = lua_tostring(T, -1);
 
 	if (msg)
 		luaL_traceback(L, T, msg, 0);
+#else /* adapted from Lua 5.1 source */
+	if (!lua_isstring(T, -1)) /* 'message' not a string? */
+		return;
+	lua_getfield(T, LUA_GLOBALSINDEX, "debug");
+	if (!lua_istable(T, -1)) {
+		lua_pop(T, 1);
+		goto merror;
+	}
+	lua_getfield(T, -1, "traceback");
+	if (!lua_isfunction(T, -1)) {
+		lua_pop(T, 2);
+		goto merror;
+	}
+	lua_pushvalue(T, -3);  /* pass error message */
+	lua_pushinteger(T, 1); /* skip traceback */
+	lua_call(T, 2, 1);     /* call debug.traceback */
+merror:
+	lua_xmove(T, L, 1);    /* move error message to L */
+#endif
 }
 
 static void
diff --git a/configure b/configure
index 6128b6a..42086db 100755
--- a/configure
+++ b/configure
@@ -5262,6 +5262,12 @@ if test "x$cmoddir" = 'x'; then :
   as_fn_error $? "unable to deduce Lua C module directory, please use --with-cmoddir=path" "$LINENO" 5
 fi
 
+ac_fn_c_check_func "$LINENO" "luaL_traceback" "ac_cv_func_luaL_traceback"
+if test "x$ac_cv_func_luaL_traceback" = xyes; then :
+  CPPFLAGS="$CPPFLAGS -DHAVE_TRACEBACK"
+fi
+
+
 # Checks for header files.
 for ac_header in stddef.h stdlib.h string.h unistd.h sys/time.h time.h pthread.h
 do :
diff --git a/configure.ac b/configure.ac
index 1e7fc76..5ef6743 100644
--- a/configure.ac
+++ b/configure.ac
@@ -92,6 +92,8 @@ AS_IF([test "x$lmoddir" = 'x'],
 AS_IF([test "x$cmoddir" = 'x'],
   [AC_MSG_ERROR([unable to deduce Lua C module directory, please use --with-cmoddir=path])])
 
+AC_CHECK_FUNC([luaL_traceback], [CPPFLAGS="$CPPFLAGS -DHAVE_TRACEBACK"])
+
 # Checks for header files.
 AC_CHECK_HEADERS([stddef.h stdlib.h string.h unistd.h sys/time.h time.h pthread.h])
 AC_CHECK_HEADERS([sys/eventfd.h sys/epoll.h sys/event.h])