add __wasi_poll_oneoff() input validation

snapshot_preview2 added the constraint that poll_oneoff() should
return EINVAL if nsubscriptions is zero. Even though poll_oneoff()
isn't implemented yet, this commit adds the necessary input
validation.

Refs: #59

src/uvwasi.c

@@ -2259,6 +2259,11 @@ uvwasi_errno_t uvwasi_poll_oneoff(uvwasi_t* uvwasi,
                                   uvwasi_event_t* out,
                                   size_t nsubscriptions,
                                   size_t* nevents) {
+  if (uvwasi == NULL || in == NULL || out == NULL ||
+      nsubscriptions == 0 || nevents == NULL) {
+    return UVWASI_EINVAL;
+  }
+
   /* TODO(cjihrig): Implement this. */
   return UVWASI_ENOTSUP;
 }

test/test-einval-input-validation.c

@@ -20,6 +20,8 @@ int main(void) {
   uvwasi_prestat_t test_prestat;
   uvwasi_dircookie_t test_dircookie = 0;
   uvwasi_filesize_t test_filesize;
+  uvwasi_subscription_t test_sub;
+  uvwasi_event_t test_event;
   uvwasi_fd_t test_fd;
 
   test_void = (void*) &test_fdstat;
@@ -145,7 +147,11 @@ int main(void) {
   CHECK(uvwasi_path_unlink_file(NULL, 3, test_str, 10));
   CHECK(uvwasi_path_unlink_file(&uvw, 3, NULL, 10));
 
-  /* TODO(cjihrig): Add uvwasi_poll_oneoff() tests. */
+  CHECK(uvwasi_poll_oneoff(NULL, &test_sub, &test_event, 5, &test_size));
+  CHECK(uvwasi_poll_oneoff(&uvw, NULL, &test_event, 5, &test_size));
+  CHECK(uvwasi_poll_oneoff(&uvw, &test_sub, NULL, 5, &test_size));
+  CHECK(uvwasi_poll_oneoff(&uvw, &test_sub, &test_event, 0, &test_size));
+  CHECK(uvwasi_poll_oneoff(&uvw, &test_sub, &test_event, 5, NULL));
 
   CHECK(uvwasi_proc_raise(NULL, UVWASI_SIGUSR2));
 

test/test-enotsup-apis.c

@@ -3,7 +3,6 @@
 
 int main(void) {
   /* TODO(cjihrig): This test is intended to be temporary. */
-  assert(UVWASI_ENOTSUP == uvwasi_poll_oneoff(NULL, NULL, NULL, 0, NULL));
   assert(UVWASI_ENOTSUP == uvwasi_sock_recv(NULL, 0, NULL, 0, 0, NULL, NULL));
   assert(UVWASI_ENOTSUP == uvwasi_sock_send(NULL, 0, NULL, 0, 0, NULL));
   assert(UVWASI_ENOTSUP == uvwasi_sock_shutdown(NULL, 0, 0));