From f05e8649eddd2180e39ebe9482fee29bf7652c97 Mon Sep 17 00:00:00 2001
From: Matthew Wild <mwild1@gmail.com>
Date: Fri, 26 Oct 2018 19:29:08 +0100
Subject: util.xpcall, util.compat: Add non-hacky multi-argument xpcall() for
 Lua 5.1

---
 util-src/GNUmakefile |  3 ++-
 util-src/compat.c    | 29 +++++++++++++++++++++++++++++
 util/xpcall.lua      |  9 +++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 util-src/compat.c
 create mode 100644 util/xpcall.lua

diff --git a/util-src/GNUmakefile b/util-src/GNUmakefile
index f2f9b1bc..054c9201 100644
--- a/util-src/GNUmakefile
+++ b/util-src/GNUmakefile
@@ -6,7 +6,8 @@ CFLAGS+=-I$(LUA_INCDIR)
 INSTALL_DATA=install -m644
 TARGET?=../util/
 
-ALL=encodings.so hashes.so net.so pposix.so signal.so table.so ringbuffer.so time.so poll.so
+ALL=encodings.so hashes.so net.so pposix.so signal.so table.so \
+    ringbuffer.so time.so poll.so compat.so
 
 ifdef RANDOM
 ALL+=crand.so
diff --git a/util-src/compat.c b/util-src/compat.c
new file mode 100644
index 00000000..34b35c35
--- /dev/null
+++ b/util-src/compat.c
@@ -0,0 +1,29 @@
+
+#include <lua.h>
+#include <lauxlib.h>
+
+
+static int lc_xpcall (lua_State *L) {
+  int ret;
+  int n_arg = lua_gettop(L);
+  /* f, msgh, p1, p2... */
+  luaL_argcheck(L, n_arg >= 2, 2, "value expected");
+  lua_pushvalue(L, 1);  /* f to top */
+  lua_pushvalue(L, 2);  /* msgh to top */
+  lua_replace(L, 1); /* msgh to 1 */
+  lua_replace(L, 2); /* f to 2 */
+  /* msgh, f, p1, p2... */
+  ret = lua_pcall(L, n_arg - 2, LUA_MULTRET, 1);
+  lua_pushboolean(L, ret == 0);
+  lua_replace(L, 1);
+  return lua_gettop(L);
+}
+
+int luaopen_util_compat(lua_State *L) {
+	lua_createtable(L, 0, 2);
+	{
+		lua_pushcfunction(L, lc_xpcall);
+		lua_setfield(L, -2, "xpcall");
+	}
+	return 1;
+}
diff --git a/util/xpcall.lua b/util/xpcall.lua
new file mode 100644
index 00000000..d2fc5011
--- /dev/null
+++ b/util/xpcall.lua
@@ -0,0 +1,9 @@
+local xpcall = xpcall;
+
+if select(2, xpcall(function (x) return x end, function () end,  "test")) ~= "test" then
+	xpcall = require"util.compat".xpcall;
+end
+
+return {
+	xpcall = xpcall;
+};
-- 
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