Update to use witx tagged unions

libc-bottom-half/cloudlibc/src/libc/poll/poll.c

@@ -21,27 +21,17 @@ int poll(struct pollfd *fds, size_t nfds, int timeout) {
       __wasi_subscription_t *subscription = &subscriptions[nevents++];
       *subscription = (__wasi_subscription_t){
           .userdata = (uintptr_t)pollfd,
-          .type = __WASI_EVENTTYPE_FD_READ,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-          .fd_readwrite.fd = pollfd->fd,
-          .fd_readwrite.flags = __WASI_SUBSCRIPTION_FD_READWRITE_POLL,
-#else
-          .u.fd_readwrite.file_descriptor = pollfd->fd,
-#endif
+          .u.tag = __WASI_EVENTTYPE_FD_READ,
+          .u.u.fd_read.file_descriptor = pollfd->fd,
       };
       created_events = true;
     }
     if ((pollfd->events & POLLWRNORM) != 0) {
       __wasi_subscription_t *subscription = &subscriptions[nevents++];
       *subscription = (__wasi_subscription_t){
           .userdata = (uintptr_t)pollfd,
-          .type = __WASI_EVENTTYPE_FD_WRITE,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-          .fd_readwrite.fd = pollfd->fd,
-          .fd_readwrite.flags = __WASI_SUBSCRIPTION_FD_READWRITE_POLL,
-#else
-          .u.fd_readwrite.file_descriptor = pollfd->fd,
-#endif
+          .u.tag = __WASI_EVENTTYPE_FD_WRITE,
+          .u.u.fd_write.file_descriptor = pollfd->fd,
       };
       created_events = true;
     }
@@ -59,14 +49,9 @@ int poll(struct pollfd *fds, size_t nfds, int timeout) {
   if (timeout >= 0) {
     __wasi_subscription_t *subscription = &subscriptions[nevents++];
     *subscription = (__wasi_subscription_t){
-        .type = __WASI_EVENTTYPE_CLOCK,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-        .clock.clock_id = __WASI_CLOCK_REALTIME,
-        .clock.timeout = (__wasi_timestamp_t)timeout * 1000000,
-#else
-        .u.clock.id = __WASI_CLOCKID_REALTIME,
-        .u.clock.timeout = (__wasi_timestamp_t)timeout * 1000000,
-#endif
+        .u.tag = __WASI_EVENTTYPE_CLOCK,
+        .u.u.clock.id = __WASI_CLOCKID_REALTIME,
+        .u.u.clock.timeout = (__wasi_timestamp_t)timeout * 1000000,
     };
   }
 
@@ -114,14 +99,17 @@ int poll(struct pollfd *fds, size_t nfds, int timeout) {
         pollfd->revents |= POLLERR;
       } else {
         // Data can be read or written.
-        pollfd->revents |=
-            event->type == __WASI_EVENTTYPE_FD_READ ? POLLRDNORM : POLLWRNORM;
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-        if (event->fd_readwrite.flags & __WASI_EVENT_FD_READWRITE_HANGUP)
-#else
-        if (event->u.fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP)
-#endif
-          pollfd->revents |= POLLHUP;
+        if (event->type == __WASI_EVENTTYPE_FD_READ) {
+            pollfd->revents |= POLLRDNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        } else if (event->type == __WASI_EVENTTYPE_FD_WRITE) {
+            pollfd->revents |= POLLWRNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        }
       }
     }
   }

libc-bottom-half/cloudlibc/src/libc/sys/ioctl/ioctl.c

@@ -14,21 +14,12 @@ int ioctl(int fildes, int request, ...) {
       // Poll the file descriptor to determine how many bytes can be read.
       __wasi_subscription_t subscriptions[2] = {
           {
-              .type = __WASI_EVENTTYPE_FD_READ,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-              .fd_readwrite.fd = fildes,
-              .fd_readwrite.flags = __WASI_SUBSCRIPTION_FD_READWRITE_POLL,
-#else
-              .u.fd_readwrite.file_descriptor = fildes,
-#endif
+              .u.tag = __WASI_EVENTTYPE_FD_READ,
+              .u.u.fd_read.file_descriptor = fildes,
           },
           {
-              .type = __WASI_EVENTTYPE_CLOCK,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-              .clock.clock_id = __WASI_CLOCK_MONOTONIC,
-#else
-              .u.clock.id = __WASI_CLOCKID_MONOTONIC,
-#endif
+              .u.tag = __WASI_EVENTTYPE_CLOCK,
+              .u.u.clock.id = __WASI_CLOCKID_MONOTONIC,
           },
       };
       __wasi_event_t events[__arraycount(subscriptions)];
@@ -58,11 +49,7 @@ int ioctl(int fildes, int request, ...) {
           return -1;
         }
         if (event->type == __WASI_EVENTTYPE_FD_READ) {
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
           *result = event->fd_readwrite.nbytes;
-#else
-          *result = event->u.fd_readwrite.nbytes;
-#endif
           return 0;
         }
       }

libc-bottom-half/cloudlibc/src/libc/sys/select/pselect.c

@@ -49,13 +49,8 @@ int pselect(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
       __wasi_subscription_t *subscription = &subscriptions[nevents++];
       *subscription = (__wasi_subscription_t){
           .userdata = fd,
-          .type = __WASI_EVENTTYPE_FD_READ,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-          .fd_readwrite.fd = fd,
-          .fd_readwrite.flags = __WASI_SUBSCRIPTION_FD_READWRITE_POLL,
-#else
-          .u.fd_readwrite.file_descriptor = fd,
-#endif
+          .u.tag = __WASI_EVENTTYPE_FD_READ,
+          .u.u.fd_read.file_descriptor = fd,
       };
     }
   }
@@ -67,13 +62,8 @@ int pselect(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
       __wasi_subscription_t *subscription = &subscriptions[nevents++];
       *subscription = (__wasi_subscription_t){
           .userdata = fd,
-          .type = __WASI_EVENTTYPE_FD_WRITE,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-          .fd_readwrite.fd = fd,
-          .fd_readwrite.flags = __WASI_SUBSCRIPTION_FD_READWRITE_POLL,
-#else
-          .u.fd_readwrite.file_descriptor = fd,
-#endif
+          .u.tag = __WASI_EVENTTYPE_FD_WRITE,
+          .u.u.fd_write.file_descriptor = fd,
       };
     }
   }
@@ -82,18 +72,10 @@ int pselect(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
   if (timeout != NULL) {
     __wasi_subscription_t *subscription = &subscriptions[nevents++];
     *subscription = (__wasi_subscription_t){
-        .type = __WASI_EVENTTYPE_CLOCK,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-        .clock.clock_id = __WASI_CLOCK_REALTIME,
-#else
-        .u.clock.id = __WASI_CLOCKID_REALTIME,
-#endif
+        .u.tag = __WASI_EVENTTYPE_CLOCK,
+        .u.u.clock.id = __WASI_CLOCKID_REALTIME,
     };
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-    if (!timespec_to_timestamp_clamp(timeout, &subscription->clock.timeout)) {
-#else
-    if (!timespec_to_timestamp_clamp(timeout, &subscription->u.clock.timeout)) {
-#endif
+    if (!timespec_to_timestamp_clamp(timeout, &subscription->u.u.clock.timeout)) {
       errno = EINVAL;
       return -1;
     }

libc-bottom-half/cloudlibc/src/libc/time/clock_nanosleep.c

@@ -29,20 +29,11 @@ int clock_nanosleep(clockid_t clock_id, int flags, const struct timespec *rqtp,
 
   // Prepare polling subscription.
   __wasi_subscription_t sub = {
-      .type = __WASI_EVENTTYPE_CLOCK,
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-      .clock.clock_id = clock_id->id,
-      .clock.flags = flags,
-#else
-      .u.clock.id = clock_id->id,
-      .u.clock.flags = flags,
-#endif
+      .u.tag = __WASI_EVENTTYPE_CLOCK,
+      .u.u.clock.id = clock_id->id,
+      .u.u.clock.flags = flags,
   };
-#ifdef __wasilibc_unmodified_upstream // non-anonymous unions
-  if (!timespec_to_timestamp_clamp(rqtp, &sub.clock.timeout))
-#else
-  if (!timespec_to_timestamp_clamp(rqtp, &sub.u.clock.timeout))
-#endif
+  if (!timespec_to_timestamp_clamp(rqtp, &sub.u.u.clock.timeout))
     return EINVAL;
 
   // Block until polling event is triggered.

libc-bottom-half/headers/public/wasi/api.h

@@ -1166,20 +1166,6 @@ _Static_assert(_Alignof(__wasi_event_fd_readwrite_t) == 8, "witx calculated alig
 _Static_assert(offsetof(__wasi_event_fd_readwrite_t, nbytes) == 0, "witx calculated offset");
 _Static_assert(offsetof(__wasi_event_fd_readwrite_t, flags) == 8, "witx calculated offset");
 
-/**
- * The contents of an $event.
- */
-typedef union __wasi_event_u_t {
-    /**
-     * When type is `eventtype::fd_read` or `eventtype::fd_write`:
-     */
-    __wasi_event_fd_readwrite_t fd_readwrite;
-
-} __wasi_event_u_t;
-
-_Static_assert(sizeof(__wasi_event_u_t) == 16, "witx calculated size");
-_Static_assert(_Alignof(__wasi_event_u_t) == 8, "witx calculated align");
-
 /**
  * An event that occurred.
  */
@@ -1195,14 +1181,15 @@ typedef struct __wasi_event_t {
     __wasi_errno_t error;
 
     /**
-     * The type of the event that occurred.
+     * The type of event that occured
      */
     __wasi_eventtype_t type;
 
     /**
-     * The contents of the event.
+     * The contents of the event, if it is an `eventtype::fd_read` or
+     * `eventtype::fd_write`. `eventtype::clock` events ignore this field.
      */
-    __wasi_event_u_t u;
+    __wasi_event_fd_readwrite_t fd_readwrite;
 
 } __wasi_event_t;
 
@@ -1211,7 +1198,7 @@ _Static_assert(_Alignof(__wasi_event_t) == 8, "witx calculated align");
 _Static_assert(offsetof(__wasi_event_t, userdata) == 0, "witx calculated offset");
 _Static_assert(offsetof(__wasi_event_t, error) == 8, "witx calculated offset");
 _Static_assert(offsetof(__wasi_event_t, type) == 10, "witx calculated offset");
-_Static_assert(offsetof(__wasi_event_t, u) == 16, "witx calculated offset");
+_Static_assert(offsetof(__wasi_event_t, fd_readwrite) == 16, "witx calculated offset");
 
 /**
  * Flags determining how to interpret the timestamp provided in
@@ -1284,21 +1271,21 @@ _Static_assert(offsetof(__wasi_subscription_fd_readwrite_t, file_descriptor) ==
 /**
  * The contents of a $subscription.
  */
-typedef union __wasi_subscription_u_t {
-    /**
-     * When type is `eventtype::clock`:
-     */
+typedef union __wasi_subscription_u_u_t {
     __wasi_subscription_clock_t clock;
-
-    /**
-     * When type is `eventtype::fd_read` or `eventtype::fd_write`:
-     */
-    __wasi_subscription_fd_readwrite_t fd_readwrite;
-
+    __wasi_subscription_fd_readwrite_t fd_read;
+    __wasi_subscription_fd_readwrite_t fd_write;
+} __wasi_subscription_u_u_t;
+typedef struct __wasi_subscription_u_t {
+    __wasi_eventtype_t tag;
+    __wasi_subscription_u_u_t u;
 } __wasi_subscription_u_t;
 
-_Static_assert(sizeof(__wasi_subscription_u_t) == 32, "witx calculated size");
+_Static_assert(sizeof(__wasi_subscription_u_t) == 40, "witx calculated size");
 _Static_assert(_Alignof(__wasi_subscription_u_t) == 8, "witx calculated align");
+_Static_assert(offsetof(__wasi_subscription_u_t, u) == 8, "witx calculated union offset");
+_Static_assert(sizeof(__wasi_subscription_u_u_t) == 32, "witx calculated union size");
+_Static_assert(_Alignof(__wasi_subscription_u_u_t) == 8, "witx calculated union align");
 
 /**
  * Subscription to an event.
@@ -1311,12 +1298,7 @@ typedef struct __wasi_subscription_t {
     __wasi_userdata_t userdata;
 
     /**
-     * The type of the event to which to subscribe.
-     */
-    __wasi_eventtype_t type;
-
-    /**
-     * The contents of the subscription.
+     * The type of the event to which to subscribe, and its contents
      */
     __wasi_subscription_u_t u;
 
@@ -1325,8 +1307,7 @@ typedef struct __wasi_subscription_t {
 _Static_assert(sizeof(__wasi_subscription_t) == 48, "witx calculated size");
 _Static_assert(_Alignof(__wasi_subscription_t) == 8, "witx calculated align");
 _Static_assert(offsetof(__wasi_subscription_t, userdata) == 0, "witx calculated offset");
-_Static_assert(offsetof(__wasi_subscription_t, type) == 8, "witx calculated offset");
-_Static_assert(offsetof(__wasi_subscription_t, u) == 16, "witx calculated offset");
+_Static_assert(offsetof(__wasi_subscription_t, u) == 8, "witx calculated offset");
 
 /**
  * Exit code generated by a process when exiting.
@@ -1617,39 +1598,21 @@ _Static_assert(_Alignof(__wasi_prestat_dir_t) == 4, "witx calculated align");
 _Static_assert(offsetof(__wasi_prestat_dir_t, pr_name_len) == 0, "witx calculated offset");
 
 /**
- * The contents of an $prestat.
+ * Information about a pre-opened capability.
  */
 typedef union __wasi_prestat_u_t {
-    /**
-     * When type is `preopentype::dir`:
-     */
     __wasi_prestat_dir_t dir;
-
 } __wasi_prestat_u_t;
-
-_Static_assert(sizeof(__wasi_prestat_u_t) == 4, "witx calculated size");
-_Static_assert(_Alignof(__wasi_prestat_u_t) == 4, "witx calculated align");
-
-/**
- * Information about a pre-opened capability.
- */
 typedef struct __wasi_prestat_t {
-    /**
-     * The type of the pre-opened capability.
-     */
-    __wasi_preopentype_t pr_type;
-
-    /**
-     * The contents of the information.
-     */
+    __wasi_preopentype_t tag;
     __wasi_prestat_u_t u;
-
 } __wasi_prestat_t;
 
 _Static_assert(sizeof(__wasi_prestat_t) == 8, "witx calculated size");
 _Static_assert(_Alignof(__wasi_prestat_t) == 4, "witx calculated align");
-_Static_assert(offsetof(__wasi_prestat_t, pr_type) == 0, "witx calculated offset");
-_Static_assert(offsetof(__wasi_prestat_t, u) == 4, "witx calculated offset");
+_Static_assert(offsetof(__wasi_prestat_t, u) == 4, "witx calculated union offset");
+_Static_assert(sizeof(__wasi_prestat_u_t) == 4, "witx calculated union size");
+_Static_assert(_Alignof(__wasi_prestat_u_t) == 4, "witx calculated union align");
 
 /**
  * @defgroup wasi_snapshot_preview1

libc-bottom-half/libpreopen/libpreopen.c

@@ -538,7 +538,7 @@ __wasilibc_populate_libpreopen(void)
             break;
         if (ret != __WASI_ERRNO_SUCCESS)
             goto oserr;
-        switch (prestat.pr_type) {
+        switch (prestat.tag) {
         case __WASI_PREOPENTYPE_DIR: {
             char *path = malloc(prestat.u.dir.pr_name_len + 1);
             if (path == NULL)