wip make select() async when using ASYNCIFY/JSPI

src/lib/libcore.js

@@ -2617,7 +2617,11 @@ function wrapSyscallFunction(x, library, isWasi) {
   post = handler + post;
 
   if (pre || post) {
-    t = modifyJSFunction(t, (args, body) => `function (${args}) {\n${pre}${body}${post}}\n`);
+    if (library[x + '__async']) {
+      t = modifyJSFunction(t, (args, body) => `async function (${args}) {\n${pre}${body}${post}}\n`);
+    } else {
+      t = modifyJSFunction(t, (args, body) => `function (${args}) {\n${pre}${body}${post}}\n`);
+    }
   }
 
   library[x] = eval('(' + t + ')');

src/lib/libsockfs.js

@@ -104,9 +104,9 @@ addToLibrary({
     },
     // node and stream ops are backend agnostic
     stream_ops: {
-      poll(stream) {
+      poll(stream, timeout) {
         var sock = stream.node.sock;
-        return sock.sock_ops.poll(sock);
+        return sock.sock_ops.poll(sock, timeout);
       },
       ioctl(stream, request, varargs) {
         var sock = stream.node.sock;
@@ -375,7 +375,7 @@ addToLibrary({
       //
       // actual sock ops
       //
-      poll(sock) {
+      poll(sock, timeout) {
         if (sock.type === {{{ cDefs.SOCK_STREAM }}} && sock.server) {
           // listen sockets should only say they're available for reading
           // if there are pending clients.

src/lib/libsyscall.js

@@ -543,7 +543,13 @@ var SyscallsLibrary = {
     return 0;
   },
   __syscall__newselect__i53abi: true,
-  __syscall__newselect: (nfds, readfds, writefds, exceptfds, timeoutInMillis) => {
+#if ASYNCIFY
+  __syscall__newselect__async: true,
+  __syscall__newselect: async (nfds, readfds, writefds, exceptfds, timeoutInMillis) =>
+#else
+  __syscall__newselect: (nfds, readfds, writefds, exceptfds, timeoutInMillis) =>
+#endif
+  {
     // readfds are supported,
     // writefds checks socket open status
     // exceptfds are supported, although on web, such exceptional conditions never arise in web sockets
@@ -586,6 +592,11 @@ var SyscallsLibrary = {
 
       if (stream.stream_ops.poll) {
         flags = stream.stream_ops.poll(stream, timeoutInMillis);
+
+#if ASYNCIFY
+        /* poll is possibly a promise */
+        flags = await flags;
+#endif
       } else {
 #if ASSERTIONS
         if (timeoutInMillis != 0) warnOnce('non-zero select() timeout not supported: ' + timeoutInMillis)