From 8d6c5fe6d182b399015cdaa6c2c6e669d3727da1 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Wed, 7 Sep 2016 00:29:21 +1000
Subject: [PATCH 1/3] cqueues:wrap: Remember to checkstack

  - Instead of re-pushing all arguments, just use lua_insert to get thread below args
  - Need to check the new stack to ensure we have enough slots
---
 src/cqueues.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/cqueues.c b/src/cqueues.c
index 807275f..2288569 100644
--- a/src/cqueues.c
+++ b/src/cqueues.c
@@ -2294,9 +2294,8 @@ static int cqueue_wrap(lua_State *L) {
 	luaL_checktype(L, 2, LUA_TFUNCTION);
 
 	newL = lua_newthread(L);
-	for (i = 2; i <= top; i++) {
-		lua_pushvalue(L, i);
-	}
+	lua_insert(L, 2);
+	luaL_checkstack(newL, top - 1, "too many arguments");
 	lua_xmove(L, newL, top - 1);
 
 	thread_add(L, Q, &I, -1);

From b8041a68bf24ea9e1f1d39c6c6c5448ac8cc1264 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Wed, 7 Sep 2016 01:04:07 +1000
Subject: [PATCH 2/3] src/cqueues: Detect if trying to resume a running or dead
 coroutine

---
 regress/145-assertion-on-dead.lua | 20 ++++++++++++++++++++
 src/cqueues.c                     | 18 +++++++++++++++---
 2 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100755 regress/145-assertion-on-dead.lua

diff --git a/regress/145-assertion-on-dead.lua b/regress/145-assertion-on-dead.lua
new file mode 100755
index 0000000..49d71d3
--- /dev/null
+++ b/regress/145-assertion-on-dead.lua
@@ -0,0 +1,20 @@
+#!/bin/sh
+_=[[
+	. "${0%%/*}/regress.sh"
+	exec runlua "$0" "$@"
+]]
+require"regress".export".*"
+
+local co = coroutine.create(function()
+	coroutine.yield()
+end)
+coroutine.resume(co) -- kick off coroutine
+coroutine.resume(co) -- resume a yield with no arguments
+-- co is now dead
+
+local cq = require"cqueues".new()
+cq:attach(co)
+check(cq:step())
+
+say"OK"
+
diff --git a/src/cqueues.c b/src/cqueues.c
index 2288569..a7e187c 100644
--- a/src/cqueues.c
+++ b/src/cqueues.c
@@ -1982,10 +1982,22 @@ static cqs_status_t cqueue_resume(lua_State *L, struct cqueue *Q, struct callinf
 		}
 	} else {
 		nargs = lua_gettop(T->L);
-		if (status != LUA_YIELD) {
+		if (status == LUA_OK && lua_getstack(T->L, 0, &(lua_Debug){}) > 0) {
+			/* already running */
+			lua_pushliteral(L, "cannot resume non-suspended coroutine");
+			I->error.value = lua_gettop(L);
+			err_setthread(L, I, T);
+			goto defunct;
+		} else if ((status != LUA_OK && status != LUA_YIELD) || nargs == 0) {
+			/* dead coroutine */
+			lua_pushliteral(L, "cannot resume dead coroutine");
+			I->error.value = lua_gettop(L);
+			err_setthread(L, I, T);
+			goto defunct;
+		} else if (status == LUA_OK) {
+			/* initial */
 			nargs -= 1;
-			assert(nargs >= 0);
-		}
+		} /* else normal yield */
 	}
 
 	timer_del(Q, &T->timer);

From 80aef124ecf4c56c253762e4da5c38069e251d77 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Fri, 9 Sep 2016 15:16:22 +1000
Subject: [PATCH 3/3] src/cqueues.c: Use != 0 instead of > 0

As requested in https://github.com/wahern/cqueues/pull/145#discussion_r78129250
---
 src/cqueues.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/cqueues.c b/src/cqueues.c
index a7e187c..547da97 100644
--- a/src/cqueues.c
+++ b/src/cqueues.c
@@ -1982,7 +1982,7 @@ static cqs_status_t cqueue_resume(lua_State *L, struct cqueue *Q, struct callinf
 		}
 	} else {
 		nargs = lua_gettop(T->L);
-		if (status == LUA_OK && lua_getstack(T->L, 0, &(lua_Debug){}) > 0) {
+		if (status == LUA_OK && lua_getstack(T->L, 0, &(lua_Debug){}) != 0) {
 			/* already running */
 			lua_pushliteral(L, "cannot resume non-suspended coroutine");
 			I->error.value = lua_gettop(L);