Fixes for socket.iowait() after daurnimator's review

src/lua/socket.c

@@ -384,24 +384,22 @@ lbox_socket_iowait(struct lua_State *L)
 {
 	if (lua_gettop(L) < 2)
 		goto usage;
+	int fh = luaL_optinteger(L, 1, -1);
 	ev_tstamp timeout = luaL_optnumber(L, 3, TIMEOUT_INFINITY);
-	if (timeout < 0)
-		goto usage;
 
 	/*
 	 * A special shortcut for gh-1204: if fd and events are nil then
 	 * just sleep. This hack simplifies integration of third-party Lua
 	 * modules with Tarantool event loop.
 	 */
-	if (unlikely(lua_isnil(L, 1) && lua_isnil(L, 2))) {
+	if (unlikely(fh < 0)) {
+		if (!lua_isnil(L, 2))
+			goto usage;
+		/* Just sleep, like poll(0, NULL, timeout) */
 		fiber_sleep(timeout);
 		return 0;
 	}
 
-	int fh = lua_tointeger(L, 1);
-	if (fh < 0)
-		goto usage;
-
 	if (likely(lua_type(L, 2) == LUA_TNUMBER)) {
 		/* Fast path: `events' is a bitmask of (COIO_READ|COIO_WRITE) */
 		int events = lua_tointeger(L, 2);

test/box/socket.result

@@ -152,6 +152,10 @@ socket.iowait(s:fd(), 'RW')
 ---
 - RW
 ...
+socket.iowait(s:fd(), 'RW', -100500)
+---
+- RW
+...
 s:readable(0)
 ---
 - true
@@ -176,9 +180,23 @@ s:wait(.01)
 ---
 - RW
 ...
+socket.iowait(nil, nil, -1)
+---
+...
 socket.iowait(nil, nil, 0.0001)
 ---
 ...
+socket.iowait(-1, nil, 0.0001)
+---
+...
+socket.iowait(nil, 'RW')
+---
+- error: 'Usage: iowait(fd, 1 | ''r'' | 2 | ''w'' | 3 | ''rw'' [, timeout])'
+...
+socket.iowait(0, nil)
+---
+- error: 'Usage: iowait(fd, 1 | ''r'' | 2 | ''w'' | 3 | ''rw'' [, timeout])'
+...
 handshake = ffi.new('char[128]')
 ---
 ...

test/box/socket.test.lua

@@ -49,13 +49,18 @@ socket.iowait(s:fd(), 2)
 socket.iowait(s:fd(), '')
 socket.iowait(s:fd(), -1)
 socket.iowait(s:fd(), 'RW')
+socket.iowait(s:fd(), 'RW', -100500)
 s:readable(0)
 s:errno() > 0
 s:error()
 s:writable(.00000000000001)
 s:writable(0)
 s:wait(.01)
+socket.iowait(nil, nil, -1)
 socket.iowait(nil, nil, 0.0001)
+socket.iowait(-1, nil, 0.0001)
+socket.iowait(nil, 'RW')
+socket.iowait(0, nil)
 
 handshake = ffi.new('char[128]')
 -- test sysread with char *