Util: Fix handling of SocketPoll of n > 1

include/mgba-util/socket.h

@@ -434,9 +434,9 @@ static inline int SocketPoll(size_t nSockets, Socket* reads, Socket* writes, Soc
 #else
 	int result = select(maxFd, &rset, &wset, &eset, timeoutMillis < 0 ? 0 : &tv);
 #endif
-	int r = 0;
+	size_t r = 0;
-	int w = 0;
+	size_t w = 0;
-	int e = 0;
+	size_t e = 0;
 	Socket j;
 	for (j = 0; j < maxFd; ++j) {
 		if (reads && FD_ISSET(j, &rset)) {
@@ -452,6 +452,21 @@ static inline int SocketPoll(size_t nSockets, Socket* reads, Socket* writes, Soc
 			++e;
 		}
 	}
+	if (reads) {
+		for (; r < nSockets; ++r) {
+			reads[r] = INVALID_SOCKET;
+		}
+	}
+	if (writes) {
+		for (; w < nSockets; ++w) {
+			writes[w] = INVALID_SOCKET;
+		}
+	}
+	if (errors) {
+		for (; e < nSockets; ++e) {
+			errors[e] = INVALID_SOCKET;
+		}
+	}
 	return result;
 }