disallow :close when invoked from a thread resumed by cqueue_step (se…

…e issue #175)

regress/175-cq-close-segfault.lua

@@ -0,0 +1,15 @@
+#!/bin/sh
+_=[[
+	. "${0%%/*}/regress.sh"
+	exec runlua "$0" "$@"
+]]
+require"regress".export".*"
+
+local cq = cqueues.new()
+local ok, why = cq:wrap(function ()
+	cq:close()
+end):loop()
+check(not ok, "expected loop to fail")
+check(tostring(why):find"cqueue running", "unexpected error (%s)", tostring(why))
+
+say"OK"

src/cqueues.c

@@ -1489,12 +1489,25 @@ static int cqueue_new(lua_State *L) {
 } /* cqueue_new() */
 
 
-static int cqueue__gc(lua_State *L) {
-	struct callinfo I;
+static int cqueue_close(lua_State *L) {
 	struct cqueue *Q = cqs_checkudata(L, 1, 1, CQUEUE_CLASS);
+	struct callinfo I;
+
+	/* disallow :close when invoked from a thread resumed by cqueue_step */
+	luaL_argcheck(L, !Q->cstack || !cstack_isrunning(Q->cstack, Q), 1, "cqueue running");
 
 	cqueue_enter_nothrow(L, &I, 1, Q);
+	cqueue_destroy(L, Q, &I);
+
+	return 0;
+} /* cqueue_close() */
 
+
+static int cqueue__gc(lua_State *L) {
+	struct cqueue *Q = cqs_checkudata(L, 1, 1, CQUEUE_CLASS);
+	struct callinfo I;
+
+	cqueue_enter_nothrow(L, &I, 1, Q);
 	cqueue_destroy(L, Q, &I);
 
 	return 0;
@@ -2872,7 +2885,7 @@ static const luaL_Reg cqueue_methods[] = {
 	{ "pollfd",  &cqueue_pollfd },
 	{ "events",  &cqueue_events },
 	{ "timeout", &cqueue_timeout },
-	{ "close",   &cqueue__gc },
+	{ "close",   &cqueue_close },
 	{ NULL,      NULL }
 }; /* cqueue_methods[] */