WIP: socket: fix dgram_length and recv* for OS X

Part of #3619.

src/lua/socket.c

@@ -268,6 +268,9 @@ static const struct lbox_sockopt_reg so_opts[] = {
 #ifdef SO_PROTOCOL
 	{"SO_PROTOCOL",		SO_PROTOCOL,		1,	0, },
 #endif
+#ifdef SO_NREAD /* available on Darwin */
+	{"SO_NREAD",		SO_NREAD,		1,	0, },
+#endif
 
 	{"SO_TYPE",		SO_TYPE,		1,	0, },
 
@@ -950,7 +953,11 @@ lbox_socket_recvfrom(struct lua_State *L)
 	int fh = lua_tointeger(L, 1);
 	int size = lua_tointeger(L, 2);
 	int flags = lua_tointeger(L, 3);
+#ifdef TARGET_OS_DARWIN
+	int dgram_length = lua_tointeger(L, 4);
+#else
 	flags |= MSG_TRUNC;
+#endif
 
 	struct sockaddr_storage fa;
 	socklen_t len = sizeof(fa);
@@ -969,7 +976,11 @@ lbox_socket_recvfrom(struct lua_State *L)
 		free(buf);
 		lua_pushnil(L);
 		return 1;
+#ifdef TARGET_OS_DARWIN
+	} else if (dgram_length > size) {
+#else
 	} else if (res > size) {
+#endif
 		free(buf);
 		lua_pushnil(L);
 		lbox_socket_push_addr(L, (struct sockaddr *)&fa, len);

src/lua/socket.lua

@@ -785,17 +785,23 @@ local function socket_dgram_length(self)
         error("socket:dgram_length() supports only a UDP socket")
     end
 
-    local iflags = get_iflags(internal.SEND_FLAGS, {'MSG_TRUNC', 'MSG_PEEK'})
-    assert(iflags ~= nil)
+    local len
+    if jit.os == 'OSX' then
+        self._errno = nil
+        len = self:getsockopt('SOL_SOCKET', 'SO_NREAD')
+    else
+        local iflags = get_iflags(internal.SEND_FLAGS, {'MSG_TRUNC', 'MSG_PEEK'})
+        assert(iflags ~= nil)
+        self._errno = nil
+        len = tonumber(ffi.C.recv(fd, nil, 0, iflags))
+    end
 
-    self._errno = nil
-    local len = ffi.C.recv(fd, nil, 0, iflags)
     if len == -1 or len == 0 then
         self._errno = boxerrno()
         return nil
     end
 
-    return tonumber(len)
+    return len
 end
 
 local function socket_recv(self, size, flags)
@@ -806,12 +812,21 @@ local function socket_recv(self, size, flags)
         return nil
     end
 
+    local dgram_length
     if self:is_udp() then
-        size = size or self:dgram_length()
+        if jit.os == 'OSX' then
+            dgram_length = self:dgram_length()
+            if dgram_length == nil then
+                return nil
+            end
+        end
+        size = size or dgram_length or self:dgram_length()
         if size == nil then
             return nil
         end
-        iflags = bit.bor(iflags, internal.SEND_FLAGS['MSG_TRUNC'])
+        if jit.os ~= 'OSX' then
+            iflags = bit.bor(iflags, internal.SEND_FLAGS['MSG_TRUNC'])
+        end
     else
         size = size or 512
     end
@@ -824,7 +839,7 @@ local function socket_recv(self, size, flags)
     if res == -1 then
         self._errno = boxerrno()
         return nil
-    elseif res > size then
+    elseif (dgram_length or res) > size then
         self._errno = boxerrno.EMSGSIZE
         return nil
     end
@@ -839,8 +854,15 @@ local function socket_recvfrom(self, size, flags)
         return nil
     end
 
+    local dgram_length
     if self:is_udp() then
-        size = size or self:dgram_length()
+        if jit.os == 'OSX' then
+            dgram_length = self:dgram_length()
+            if dgram_length == nil then
+                return nil
+            end
+        end
+        size = size or dgram_length or self:dgram_length()
         if size == nil then
             return nil
         end
@@ -849,7 +871,12 @@ local function socket_recvfrom(self, size, flags)
     end
 
     self._errno = nil
-    local res, from = internal.recvfrom(fd, size, iflags)
+    local res, from
+    if jit.os == 'OSX' then
+        res, from = internal.recvfrom(fd, size, iflags, dgram_length)
+    else
+        res, from = internal.recvfrom(fd, size, iflags)
+    end
     if res == nil then
         self._errno = boxerrno()
         return nil, from