From b38aa77e6aa5cbb843082887f54ed58c6272bd13 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Wed, 2 Apr 2025 11:23:25 -0700
Subject: [PATCH 1/6] Implement a C ABI for async import/export communication

This commit is an implementation of a solution for
WebAssembly/component-model#485 for Rust. This should enable releasing
multiple versions of `wit-bindgen` into the wild and have them all work
together for now. Integration with `wasi-libc` will come in the future
in theory.
---
 ...lloc.sh => rebuild-libwit-bindgen-cabi.sh} |  48 +++++---
 crates/guest-rust/rt/README.md                |  10 +-
 crates/guest-rust/rt/build.rs                 |   4 +-
 crates/guest-rust/rt/src/async_support.rs     | 111 ++++++++++++------
 .../guest-rust/rt/src/async_support/cabi.rs   | 105 +++++++++++++++++
 .../rt/src/async_support/waitable.rs          |  79 +++++++++++--
 crates/guest-rust/rt/src/cabi_realloc.o       | Bin 261 -> 0 bytes
 crates/guest-rust/rt/src/cabi_realloc.rs      |  11 --
 crates/guest-rust/rt/src/lib.rs               |   8 +-
 .../guest-rust/rt/src/libwit_bindgen_cabi.a   | Bin 0 -> 628 bytes
 .../rt/src/libwit_bindgen_cabi_realloc.a      | Bin 412 -> 0 bytes
 .../{cabi_realloc.c => wit_bindgen_cabi.c}    |   9 +-
 crates/guest-rust/rt/src/wit_bindgen_cabi.o   | Bin 0 -> 378 bytes
 crates/guest-rust/rt/src/wit_bindgen_cabi.rs  |  22 ++++
 14 files changed, 321 insertions(+), 86 deletions(-)
 rename ci/{rebuild-libcabi-realloc.sh => rebuild-libwit-bindgen-cabi.sh} (69%)
 create mode 100644 crates/guest-rust/rt/src/async_support/cabi.rs
 delete mode 100644 crates/guest-rust/rt/src/cabi_realloc.o
 delete mode 100644 crates/guest-rust/rt/src/cabi_realloc.rs
 create mode 100644 crates/guest-rust/rt/src/libwit_bindgen_cabi.a
 delete mode 100644 crates/guest-rust/rt/src/libwit_bindgen_cabi_realloc.a
 rename crates/guest-rust/rt/src/{cabi_realloc.c => wit_bindgen_cabi.c} (58%)
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi.o
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi.rs

diff --git a/ci/rebuild-libcabi-realloc.sh b/ci/rebuild-libwit-bindgen-cabi.sh
similarity index 69%
rename from ci/rebuild-libcabi-realloc.sh
rename to ci/rebuild-libwit-bindgen-cabi.sh
index 0d76fa947..1a903c06b 100755
--- a/ci/rebuild-libcabi-realloc.sh
+++ b/ci/rebuild-libwit-bindgen-cabi.sh
@@ -41,13 +41,15 @@ set -ex
 
 version=$(./ci/print-current-version.sh | sed 's/\./_/g')
 
-sym=cabi_realloc_wit_bindgen_$version
+realloc=cabi_realloc_wit_bindgen_$version
+wasip3_task_set=wasip3_task_set_wit_bindgen_$version
+wasip3_task_get=wasip3_task_get_wit_bindgen_$version
 
-cat >./crates/guest-rust/rt/src/cabi_realloc.rs <<-EOF
+cat >./crates/guest-rust/rt/src/wit_bindgen_cabi.rs <<-EOF
 // This file is generated by $0
 
 #[unsafe(no_mangle)]
-pub unsafe extern "C" fn $sym(
+pub unsafe extern "C" fn $realloc(
     old_ptr: *mut u8,
     old_len: usize,
     align: usize,
@@ -55,31 +57,49 @@ pub unsafe extern "C" fn $sym(
 ) -> *mut u8 {
     crate::cabi_realloc(old_ptr, old_len, align, new_len)
 }
+
+static mut WASIP3_TASK: *mut u8 = core::ptr::null_mut();
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn $wasip3_task_set(ptr: *mut u8) -> *mut u8 {
+    unsafe {
+        let ret = WASIP3_TASK;
+        WASIP3_TASK = ptr;
+        ret
+    }
+}
 EOF
 
-cat >./crates/guest-rust/rt/src/cabi_realloc.c <<-EOF
+cat >./crates/guest-rust/rt/src/wit_bindgen_cabi.c <<-EOF
 // This file is generated by $0
 
 #include <stdint.h>
 
-extern void *$sym(void *ptr, size_t old_size, size_t align, size_t new_size);
+extern void *$realloc(void *ptr, size_t old_size, size_t align, size_t new_size);
 
 __attribute__((__weak__, __export_name__("cabi_realloc")))
 void *cabi_realloc(void *ptr, size_t old_size, size_t align, size_t new_size) {
-  return $sym(ptr, old_size, align, new_size);
+  return $realloc(ptr, old_size, align, new_size);
+}
+
+extern void *$wasip3_task_set(void *ptr);
+
+__attribute__((__weak__))
+void *wasip3_task_set(void *ptr) {
+  return $wasip3_task_set(ptr);
 }
 EOF
 
-rm -f crates/guest-rust/rt/src/cabi_realloc.o
-$WASI_SDK_PATH/bin/clang crates/guest-rust/rt/src/cabi_realloc.c \
-  -O -c -o crates/guest-rust/rt/src/cabi_realloc.o
+rm -f crates/guest-rust/rt/src/wit_bindgen_cabi.o
+$WASI_SDK_PATH/bin/clang crates/guest-rust/rt/src/wit_bindgen_cabi.c \
+  -O -c -o crates/guest-rust/rt/src/wit_bindgen_cabi.o
 
 # Remove the `producers` section. This appears to differ whether the host for
 # clang is either macOS or Linux. Not needed here anyway, so discard it to help
 # either host produce the same object.
-wasm-tools strip -d producers ./crates/guest-rust/rt/src/cabi_realloc.o \
-  -o ./crates/guest-rust/rt/src/cabi_realloc.o
+wasm-tools strip -d producers ./crates/guest-rust/rt/src/wit_bindgen_cabi.o \
+  -o ./crates/guest-rust/rt/src/wit_bindgen_cabi.o
 
-rm -f crates/guest-rust/rt/src/libwit_bindgen_cabi_realloc.a
-$WASI_SDK_PATH/bin/llvm-ar crus crates/guest-rust/rt/src/libwit_bindgen_cabi_realloc.a \
-  crates/guest-rust/rt/src/cabi_realloc.o
+rm -f crates/guest-rust/rt/src/libwit_bindgen_cabi.a
+$WASI_SDK_PATH/bin/llvm-ar crus crates/guest-rust/rt/src/libwit_bindgen_cabi.a \
+  crates/guest-rust/rt/src/wit_bindgen_cabi.o
diff --git a/crates/guest-rust/rt/README.md b/crates/guest-rust/rt/README.md
index 2c9c8b2cc..c2824b04c 100644
--- a/crates/guest-rust/rt/README.md
+++ b/crates/guest-rust/rt/README.md
@@ -8,13 +8,13 @@ crate is to contain "runtime" code related to the macro-expansion of the
 be removed in some situations.
 
 This crate contains a precompiled object file and archive at
-`src/cabi_realloc.o` and `src/libwit_bindgen_cabi_realloc.a`. This is compiled
-from the source `src/cabi_realloc.c` and is checked in as precompiled to avoid
-needing a C compiler at compile-time which isn't always available. This object
-file is only used on wasm targets.
+`src/wit_bindgen_cabi.o` and `src/libwit_bindgen_cabi.a`. This is compiled
+from the source `src/wit_bindgen_cabi.c` and is checked in as precompiled to
+avoid needing a C compiler at compile-time which isn't always available. This
+object file is only used on wasm targets.
 
 The object file is compiled by
-[this script]https://github.com/bytecodealliance/wit-bindgen/blob/main/ci/rebuild-libcabi-realloc.sh)
+[this script]https://github.com/bytecodealliance/wit-bindgen/blob/main/ci/rebuild-libwit-bindgen-cabi.sh)
 and is verified in repository continuous integration that the checked-in
 versions match what CI produces.
 
diff --git a/crates/guest-rust/rt/build.rs b/crates/guest-rust/rt/build.rs
index 4bfbed9e0..c8c95090b 100644
--- a/crates/guest-rust/rt/build.rs
+++ b/crates/guest-rust/rt/build.rs
@@ -16,10 +16,10 @@ fn main() {
 
     let mut src = env::current_dir().unwrap();
     src.push("src");
-    src.push("libwit_bindgen_cabi_realloc.a");
+    src.push("libwit_bindgen_cabi.a");
 
     let dst_name = format!(
-        "wit_bindgen_cabi_realloc{}",
+        "wit_bindgen_cabi{}",
         env!("CARGO_PKG_VERSION").replace(".", "_")
     );
     let dst = out_dir.join(format!("lib{dst_name}.a"));
diff --git a/crates/guest-rust/rt/src/async_support.rs b/crates/guest-rust/rt/src/async_support.rs
index 5a9f25fd0..5749e3364 100644
--- a/crates/guest-rust/rt/src/async_support.rs
+++ b/crates/guest-rust/rt/src/async_support.rs
@@ -8,6 +8,7 @@ extern crate std;
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::boxed::Box;
 use std::collections::HashMap;
+use std::ffi::c_void;
 use std::fmt::{self, Debug, Display};
 use std::future::Future;
 use std::mem;
@@ -15,7 +16,7 @@ use std::pin::Pin;
 use std::ptr;
 use std::string::String;
 use std::sync::Arc;
-use std::task::{Context, Poll, Wake, Waker};
+use std::task::{Context, Poll, Wake};
 use std::vec::Vec;
 
 use futures::channel::oneshot;
@@ -36,6 +37,7 @@ macro_rules! rtdebug {
 }
 
 mod abi_buffer;
+mod cabi;
 mod future_support;
 mod stream_support;
 mod waitable;
@@ -60,21 +62,32 @@ struct FutureState {
     tasks: Option<FuturesUnordered<BoxFuture>>,
     /// The waitable set containing waitables created by this task, if any.
     waitable_set: Option<u32>,
-    /// A map of waitables to the corresponding waker and completion code.
-    ///
-    /// This is primarily filled in and managed by `WaitableOperation<S>`. The
-    /// waker here comes straight from `std::task::Context` and the pointer is
-    /// otherwise stored within the `WaitableOperation<S>` The raw pointer here
-    /// has a disconnected lifetime with each future but the management of the
-    /// internal states with respect to drop should always ensure that this is
-    /// only ever pointing to active waitable operations.
-    ///
-    /// When a waitable notification is received the corresponding entry in this
-    /// map is removed, the status code is filled in, and the waker is notified.
-    wakers: HashMap<u32, (Waker, *mut Option<u32>)>,
+
+    /// State of all waitables in `waitable_set`, and the ptr/callback they're
+    /// associated with.
+    waitables: HashMap<u32, (*mut c_void, unsafe extern "C" fn(*mut c_void, u32))>,
+
+    /// Raw structure used to pass to `cabi::wasip3_task_set`
+    wasip3_task: cabi::wasip3_task,
 }
 
 impl FutureState {
+    fn new(future: BoxFuture) -> FutureState {
+        FutureState {
+            todo: 0,
+            tasks: Some([future].into_iter().collect()),
+            waitable_set: None,
+            waitables: HashMap::new(),
+            wasip3_task: cabi::wasip3_task {
+                // This pointer is filled in before calling `wasip3_task_set`.
+                ptr: ptr::null_mut(),
+                version: cabi::WASIP3_TASK_V1,
+                waitable_register,
+                waitable_unregister,
+            },
+        }
+    }
+
     fn get_or_create_waitable_set(&mut self) -> u32 {
         *self.waitable_set.get_or_insert_with(waitable_set_new)
     }
@@ -88,7 +101,32 @@ impl FutureState {
     }
 
     fn remaining_work(&self) -> bool {
-        self.todo > 0 || !self.wakers.is_empty()
+        self.todo > 0 || !self.waitables.is_empty()
+    }
+}
+
+unsafe extern "C" fn waitable_register(
+    ptr: *mut c_void,
+    waitable: u32,
+    callback: unsafe extern "C" fn(*mut c_void, u32),
+    callback_ptr: *mut c_void,
+) -> *mut c_void {
+    let ptr = ptr.cast::<FutureState>();
+    assert!(!ptr.is_null());
+    (*ptr).add_waitable(waitable);
+    match (*ptr).waitables.insert(waitable, (callback_ptr, callback)) {
+        Some((prev, _)) => prev,
+        None => ptr::null_mut(),
+    }
+}
+
+unsafe extern "C" fn waitable_unregister(ptr: *mut c_void, waitable: u32) -> *mut c_void {
+    let ptr = ptr.cast::<FutureState>();
+    assert!(!ptr.is_null());
+    (*ptr).remove_waitable(waitable);
+    match (*ptr).waitables.remove(&waitable) {
+        Some((prev, _)) => prev,
+        None => ptr::null_mut(),
     }
 }
 
@@ -145,6 +183,22 @@ unsafe fn poll(state: *mut FutureState) -> Poll<()> {
         }
     }
 
+    // Finish our `wasip3_task` by initializing its self-referential pointer,
+    // and then register it for the duration of this function with
+    // `wasip3_task_set`. The previous value of `wasip3_task_set` will get
+    // restored when this function returns.
+    struct ResetTask(*mut cabi::wasip3_task);
+    impl Drop for ResetTask {
+        fn drop(&mut self) {
+            unsafe {
+                cabi::wasip3_task_set(self.0);
+            }
+        }
+    }
+    (*state).wasip3_task.ptr = state.cast();
+    let prev = cabi::wasip3_task_set(&mut (*state).wasip3_task);
+    let _reset = ResetTask(prev);
+
     loop {
         if let Some(futures) = (*state).tasks.as_mut() {
             let old = CURRENT;
@@ -191,16 +245,9 @@ pub fn first_poll<T: 'static>(
     future: impl Future<Output = T> + 'static,
     fun: impl FnOnce(&T) + 'static,
 ) -> i32 {
-    let state = Box::into_raw(Box::new(FutureState {
-        todo: 0,
-        tasks: Some(
-            [Box::pin(future.map(|v| fun(&v))) as BoxFuture]
-                .into_iter()
-                .collect(),
-        ),
-        waitable_set: None,
-        wakers: HashMap::new(),
-    }));
+    let state = Box::into_raw(Box::new(FutureState::new(Box::pin(
+        future.map(|v| fun(&v)),
+    ))));
     let done = unsafe { poll(state).is_ready() };
     unsafe { callback_code(state, done) }
 }
@@ -339,9 +386,8 @@ unsafe fn callback_with_state(
                 "EVENT_{{STREAM,FUTURE}}_{{READ,WRITE}}({event0:#x}, {event1:#x}, {event2:#x})"
             );
             (*state).remove_waitable(event1 as u32);
-            let (waker, code) = (*state).wakers.remove(&(event1 as u32)).unwrap();
-            *code = Some(event2 as u32);
-            waker.wake();
+            let (ptr, callback) = (*state).waitables.remove(&(event1 as u32)).unwrap();
+            callback(ptr, event2 as u32);
 
             let done = poll(state).is_ready();
             callback_code(state, done)
@@ -469,16 +515,7 @@ pub fn spawn(future: impl Future<Output = ()> + 'static) {
 // TODO: refactor so `'static` bounds aren't necessary
 pub fn block_on<T: 'static>(future: impl Future<Output = T> + 'static) -> T {
     let (tx, mut rx) = oneshot::channel();
-    let state = &mut FutureState {
-        todo: 0,
-        tasks: Some(
-            [Box::pin(future.map(move |v| drop(tx.send(v)))) as BoxFuture]
-                .into_iter()
-                .collect(),
-        ),
-        waitable_set: None,
-        wakers: HashMap::new(),
-    };
+    let state = &mut FutureState::new(Box::pin(future.map(move |v| drop(tx.send(v)))) as BoxFuture);
     loop {
         match unsafe { poll(state) } {
             Poll::Ready(()) => break rx.try_recv().unwrap().unwrap(),
diff --git a/crates/guest-rust/rt/src/async_support/cabi.rs b/crates/guest-rust/rt/src/async_support/cabi.rs
new file mode 100644
index 000000000..59958da8c
--- /dev/null
+++ b/crates/guest-rust/rt/src/async_support/cabi.rs
@@ -0,0 +1,105 @@
+//! Definition of the "C ABI" of how imported functions interact with exported
+//! tasks.
+//!
+//! Ok this crate is written in Rust, why in the world does this exist? This
+//! comment is intended to explain this rationale but the tl;dr; is we want
+//! this to work:
+//!
+//! * Within a single component ...
+//! * One rust crate uses `wit-bindgen 0.A.0` to generate an exported function.
+//! * One rust crate uses `wit-bindgen 0.B.0` to bind an imported function.
+//! * The two crates are connected in the application with
+//!   `std::future::Future`.
+//!
+//! Without this module this situation won't work because 0.A.0 has no
+//! knowledge of 0.B.0 meaning that when 0.B.0 decides to block it won't know
+//! where to register its `waitable` within a `waitable-set`.
+//!
+//! To solve this problem the long-term intention is that something will live
+//! in `wasi-libc` itself, but in the meantime it's living "somewhere" within
+//! `wit-bindgen 0.*.0`. Specifically all `wit-bindgen` versions will all
+//! reference, via C linkage, a single function which is used to manipulate a
+//! single pointer in linear memory. This pointer is a `wasip3_task` structure
+//! which has all the various fields to use it.
+//!
+//! The `wasip3_task_set` symbol is itself defined in C inside of the
+//! `src/wit_bindgen_cabi.c` file at this time, specifically because it's
+//! annotated with `__weak__` meaning that any definition of it suffices. This
+//! isn't possible to define in stable Rust (specifically `__weak__`).
+//!
+//! Once `wasip3_task_set` is defined everything then operates via indirection,
+//! aka based off the returned pointer. The intention is that exported functions
+//! will set this (it's sort of like an executor) and then imported functions
+//! will all use this as the source of registering waitables. In the end that
+//! means that it's possible to share types with `std::future::Future` that
+//! are backed at the ABI level with this "channel".
+//!
+//! In the future it's hoped that this can move into `wasi-libc` itself, or if
+//! `wasi-libc` provides something else that would be prioritized over this.
+//! For now this is basically an affordance that we're going to be frequently
+//! releaseing new major versions of `wit-bindgen` and we don't want to force
+//! applications to all be using the exact same version of the bindings
+//! generator and async bindings.
+//!
+//! Additionally for now this file is serving as documentation of this
+//! interface.
+
+use core::ffi::c_void;
+
+extern "C" {
+    /// Sets the global task pointer to `ptr` provided. Returns the previous
+    /// value.
+    ///
+    /// This function acts as both a dual getter and a setter. To get the
+    /// current task pointer a dummy `ptr` can be provided (e.g. NULL) and then
+    /// it's passed back when you're done working with it. When setting the
+    /// current task pointer it's recommended to call this and then call it
+    /// again with the previous value when the tasks's work is done.
+    ///
+    /// For executors they need to ensure that the `ptr` passed in lives for
+    /// the entire lifetime of the component model task.
+    pub fn wasip3_task_set(ptr: *mut wasip3_task) -> *mut wasip3_task;
+}
+
+/// The first version of `wasip3_task` which implies the existence of the
+/// fields `ptr`, `waitable_register`, and `waitable_unregister`.
+pub const WASIP3_TASK_V1: u32 = 1;
+
+/// Indirect "vtable" used to connect imported functions and exported tasks.
+/// Executors (e.g. exported functions) define and manage this while imports
+/// use it.
+#[repr(C)]
+pub struct wasip3_task {
+    /// Currently `WASIP3_TASK_V1`. Indicates what fields are present next
+    /// depending on the version here.
+    pub version: u32,
+
+    /// Private pointer owned by the `wasip3_task` itself, passed to callbacks
+    /// below as the first argument.
+    pub ptr: *mut c_void,
+
+    /// Register a new `waitable` for this exported task.
+    ///
+    /// This exported task will add `waitable` to its `waitable-set`. When it
+    /// becomes ready then `callback` will be invoked with the ready code as
+    /// well as the `callback_ptr` provided.
+    ///
+    /// If `waitable` was previously registered with this task then the
+    /// previuos `callback_ptr` is returned. Otherwise `NULL` is returned.
+    ///
+    /// It's the caller's responsibility to ensure that `callback_ptr` is valid
+    /// until `callback` is invoked, `waitable_unregister` is invoked, or
+    /// `waitable_register` is called again to overwrite the value.
+    pub waitable_register: unsafe extern "C" fn(
+        ptr: *mut c_void,
+        waitable: u32,
+        callback: unsafe extern "C" fn(callback_ptr: *mut c_void, code: u32),
+        callback_ptr: *mut c_void,
+    ) -> *mut c_void,
+
+    /// Removes the `waitable` from this task's `waitable-set`.
+    ///
+    /// Returns the `callback_ptr` passed to `waitable_register` if present, or
+    /// `NULL` if it's not present.
+    pub waitable_unregister: unsafe extern "C" fn(ptr: *mut c_void, waitable: u32) -> *mut c_void,
+}
diff --git a/crates/guest-rust/rt/src/async_support/waitable.rs b/crates/guest-rust/rt/src/async_support/waitable.rs
index 956fc46aa..2f7dd235d 100644
--- a/crates/guest-rust/rt/src/async_support/waitable.rs
+++ b/crates/guest-rust/rt/src/async_support/waitable.rs
@@ -1,11 +1,13 @@
 //! Generic support for "any waitable" and performing asynchronous operations on
 //! that waitable.
 
-use super::results;
+use super::{cabi, results};
+use std::ffi::c_void;
 use std::marker;
 use std::mem;
 use std::pin::Pin;
-use std::task::{Context, Poll};
+use std::ptr;
+use std::task::{Context, Poll, Waker};
 
 /// Generic future-based operation on any "waitable" in the component model.
 ///
@@ -42,6 +44,8 @@ struct CompletionStatus {
     /// happens.
     code: Option<u32>,
 
+    waker: Option<Waker>,
+
     /// This is necessary to ensure that `Pin<&mut CompletionStatus>` carries
     /// the "pin guarantee", basically to mean that it's not safe to construct
     /// `Pin<&mut CompletionStatus>` and it must somehow require `unsafe` code.
@@ -130,6 +134,7 @@ where
             state: WaitableOperationState::Start(state),
             completion_status: CompletionStatus {
                 code: None,
+                waker: None,
                 _pinned: marker::PhantomPinned,
             },
         }
@@ -154,12 +159,38 @@ where
     /// * Fill in `completion_status` with the result of a completion event.
     /// * Call `cx.waker().wake()`.
     pub fn register_waker(self: Pin<&mut Self>, waitable: u32, cx: &mut Context) {
-        let (_, completion_status) = self.pin_project();
+        let (_, mut completion_status) = self.pin_project();
+        debug_assert!(completion_status.as_mut().code_mut().is_none());
+        *completion_status.as_mut().waker_mut() = Some(cx.waker().clone());
+
+        // SAFETY: There's quite a lot going on here. First is the usage of
+        // `task` below, and for that see `unregister_waker` below for why this
+        // pattern should be safe.
+        //
+        // Otherwise we're handing off a pointer to `completion_status` to the
+        // `task` itself. That should be safe as we're guaranteed, via
+        // `Pin<&mut Self>`, that before `&mut Self` is deallocated the
+        // destructor will be run which will perform de-registration via
+        // cancellation.
         unsafe {
-            (*super::CURRENT).add_waitable(waitable);
-            (*super::CURRENT)
-                .wakers
-                .insert(waitable, (cx.waker().clone(), completion_status.code_mut()));
+            let task = cabi::wasip3_task_set(ptr::null_mut());
+            assert!(!task.is_null());
+            assert!((*task).version >= cabi::WASIP3_TASK_V1);
+            let ptr: *mut CompletionStatus = completion_status.get_unchecked_mut();
+            let prev = ((*task).waitable_register)((*task).ptr, waitable, cabi_wake, ptr.cast());
+            // We might be inserting a waker for the first time or overwriting
+            // the previous waker. Only assert the expected value here if the
+            // previous value was non-null.
+            if !prev.is_null() {
+                assert_eq!(ptr, prev.cast());
+            }
+            cabi::wasip3_task_set(task);
+        }
+
+        unsafe extern "C" fn cabi_wake(ptr: *mut c_void, code: u32) {
+            let ptr: &mut CompletionStatus = &mut *ptr.cast::<CompletionStatus>();
+            ptr.code = Some(code);
+            ptr.waker.take().unwrap().wake()
         }
     }
 
@@ -169,17 +200,37 @@ where
     /// This relinquishes control of the original `completion_status` pointer
     /// passed to `register_waker` after this call has completed.
     pub fn unregister_waker(self: Pin<&mut Self>, waitable: u32) {
+        // SAFETY: the contract of `wasip3_task_set` is that the returned
+        // pointer is valid for the lifetime of our entire task, so it's valid
+        // for this stack frame. Additionally we assert it's non-null to
+        // double-check it's initialized and additionlly check the version for
+        // the fields that we access.
+        //
+        // Otherwise the `waitable_unregister` callback should be safe if we
+        // pass a waitable that we own and the task's own pointer.
         unsafe {
-            (*super::CURRENT).remove_waitable(waitable);
-            let _prev = (*super::CURRENT).wakers.remove(&waitable);
-            // Note that `_prev` here is not guaranteed to be either `Some` or
-            // `None`. A racy completion notification may have come in and
+            let task = cabi::wasip3_task_set(ptr::null_mut());
+            assert!(!task.is_null());
+            assert!((*task).version >= cabi::WASIP3_TASK_V1);
+            let prev = ((*task).waitable_unregister)((*task).ptr, waitable);
+
+            // Note that `_prev` here is not guaranteed to be either `NULL` or
+            // not. A racy completion notification may have come in and
             // removed our waitable from the map even though we're in the
             // `InProgress` state, meaning it may not be present.
             //
             // The main thing is that after this method is called the
             // internal `completion_status` is guaranteed to no longer be in
-            // `FuturesState`.
+            // `task`.
+            //
+            // Note, though, that if present this must be our `CompletionStatus`
+            // pointer.
+            if !prev.is_null() {
+                let ptr: *mut CompletionStatus = self.pin_project().1.get_unchecked_mut();
+                assert_eq!(ptr, prev.cast());
+            }
+
+            cabi::wasip3_task_set(task);
         }
     }
 
@@ -374,4 +425,8 @@ impl CompletionStatus {
     fn code_mut(self: Pin<&mut Self>) -> &mut Option<u32> {
         unsafe { &mut self.get_unchecked_mut().code }
     }
+
+    fn waker_mut(self: Pin<&mut Self>) -> &mut Option<Waker> {
+        unsafe { &mut self.get_unchecked_mut().waker }
+    }
 }
diff --git a/crates/guest-rust/rt/src/cabi_realloc.o b/crates/guest-rust/rt/src/cabi_realloc.o
deleted file mode 100644
index 3ce8afc4655bba1c34668a23282ec25d820a93dd..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 261
zcmZ9GK~BRk5Jmqum0CijSnOCe3wEWbNZbIr<_J?K43>rCAjfH8RW891xMyA1p#J64
z|1%F}=m-E^&~|djp@Z5Mg@j$j>|GEOxs$Gsp9(nPMQa+zQH=L}%X^o&apA>E;59$o
z^ZKuK&77%=(k6Z#Lz`S5IGM%^z2}A^Of}8_p8}Ovq*0@$TGfUA%E2XWrdi_61*>M?
zC!+8}XG0C>GD_CDdwhP{ObBzrZIw*4lD~^dW0XNHt8V-?SXtjU#t+Nc;A~jQM>+y=
Ck4ta>

diff --git a/crates/guest-rust/rt/src/cabi_realloc.rs b/crates/guest-rust/rt/src/cabi_realloc.rs
deleted file mode 100644
index cc738191e..000000000
--- a/crates/guest-rust/rt/src/cabi_realloc.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-// This file is generated by ./ci/rebuild-libcabi-realloc.sh
-
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn cabi_realloc_wit_bindgen_0_41_0(
-    old_ptr: *mut u8,
-    old_len: usize,
-    align: usize,
-    new_len: usize,
-) -> *mut u8 {
-    crate::cabi_realloc(old_ptr, old_len, align, new_len)
-}
diff --git a/crates/guest-rust/rt/src/lib.rs b/crates/guest-rust/rt/src/lib.rs
index 31b60afb0..608d04846 100644
--- a/crates/guest-rust/rt/src/lib.rs
+++ b/crates/guest-rust/rt/src/lib.rs
@@ -13,9 +13,9 @@ use core::ptr::{self, NonNull};
 #[doc(hidden)]
 pub use bitflags;
 
-/// For more information about this see `./ci/rebuild-libcabi-realloc.sh`.
+/// For more information about this see `./ci/rebuild-libwit-bindgen-cabi.sh`.
 #[cfg(not(target_env = "p2"))]
-mod cabi_realloc;
+mod wit_bindgen_cabi;
 
 /// This function is called from generated bindings and will be deleted by
 /// the linker. The purpose of this function is to force a reference to the
@@ -23,7 +23,7 @@ mod cabi_realloc;
 /// command line. That way `wasm-ld` will pick it up, see it needs to be
 /// exported, and then export it.
 ///
-/// For more information about this see `./ci/rebuild-libcabi-realloc.sh`.
+/// For more information about this see `./ci/rebuild-libwit-bindgen-cabi.sh`.
 pub fn maybe_link_cabi_realloc() {
     #[cfg(all(target_family = "wasm", not(target_env = "p2")))]
     {
@@ -55,7 +55,7 @@ pub fn maybe_link_cabi_realloc() {
 /// NB: this function is called by a generated function in the
 /// `cabi_realloc` module above. It's otherwise never explicitly called.
 ///
-/// For more information about this see `./ci/rebuild-libcabi-realloc.sh`.
+/// For more information about this see `./ci/rebuild-libwit-bindgen-cabi.sh`.
 #[cfg(not(target_env = "p2"))]
 pub unsafe fn cabi_realloc(
     old_ptr: *mut u8,
diff --git a/crates/guest-rust/rt/src/libwit_bindgen_cabi.a b/crates/guest-rust/rt/src/libwit_bindgen_cabi.a
new file mode 100644
index 0000000000000000000000000000000000000000..afac3d661f9bd64b0d549812be0aeadf30b22c80
GIT binary patch
literal 628
zcmZ{hy-ve05Xa9>DymSCNDPPp5m=*s&{n{Jx&Q+ckKj7t8muNx<v1;!3L_gY!OR=*
zY&b2g(h5%U$DL3A``!8MhO6j#;I#d1>r~v;y}J8;zq?KtIsib;`Yu<*L%|gCB*`L}
z@mx%LO!Iuqa?}9r-7;&Df6nd(W9ZC;W}%QzF-lfeX=QDvy?I{=RNX4?Wxu~n=v`g^
zRx;E)Pl-V$2XtsJjFH8Vn2o*@+d?^Y8B2sju2_m`rsk%_GJIO?kX4~Ntbf5etE}^#
z*8fT*rQ9)NrYE5=(ri@7NQ+FGfrSZ@iIK7>kUftyszrf1C)5KUeBx8z@?MR>zGDL3
z+wuy7JwrYgGN$#fGE#$2Lbo+MfSTp*P=ZHlA7&<pjzaT)t=q@Ddz(Uoz>x(HuI4I6
xgNa-h3UfPf(jw7f%98>EH!YUf%{a+Ip5%e6aD)nFgiSr4U>?+S5z8jN=pVlIo+$tT

literal 0
HcmV?d00001

diff --git a/crates/guest-rust/rt/src/libwit_bindgen_cabi_realloc.a b/crates/guest-rust/rt/src/libwit_bindgen_cabi_realloc.a
deleted file mode 100644
index c14633576beda7faa3bcd443d3b828bcc7df32f2..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 412
zcmZ{gzfQw25XSGEN-d#MA~q(B#8%p-QPc^s6lQjoixW(+a2(_~{F%y2@CdvoP76{%
z;*)IoK7IGQlTR;%Egvq!CI78tQ10KuoAWgN3FILFpg*^zC=^*Kv~Eg(VYO(M{6FG4
z%XX-Az4}IaqG;<Li3gaEwqCepc@RkR91&?{q_9-Wy0LEzptnzk)96JxDwMgaq@jee
z6(#%BF_Cwbm8GNm&Xi6yhMXw0#3!F%2;&&1Llj_mgfVd7$QcjfcP}`Ev$0>|QJIQO
zK6;12C;n-S0pid~{}qeP&DHe?VTy1bIbkd5r%T~FD_b^;>Tb8eywXh}bUT~0sxou=
G>cTJbpJx&P

diff --git a/crates/guest-rust/rt/src/cabi_realloc.c b/crates/guest-rust/rt/src/wit_bindgen_cabi.c
similarity index 58%
rename from crates/guest-rust/rt/src/cabi_realloc.c
rename to crates/guest-rust/rt/src/wit_bindgen_cabi.c
index 9847aef29..dc274e503 100644
--- a/crates/guest-rust/rt/src/cabi_realloc.c
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi.c
@@ -1,4 +1,4 @@
-// This file is generated by ./ci/rebuild-libcabi-realloc.sh
+// This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
 
 #include <stdint.h>
 
@@ -8,3 +8,10 @@ __attribute__((__weak__, __export_name__("cabi_realloc")))
 void *cabi_realloc(void *ptr, size_t old_size, size_t align, size_t new_size) {
   return cabi_realloc_wit_bindgen_0_41_0(ptr, old_size, align, new_size);
 }
+
+extern void *wasip3_task_set_wit_bindgen_0_41_0(void *ptr);
+
+__attribute__((__weak__))
+void *wasip3_task_set(void *ptr) {
+  return wasip3_task_set_wit_bindgen_0_41_0(ptr);
+}
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi.o b/crates/guest-rust/rt/src/wit_bindgen_cabi.o
new file mode 100644
index 0000000000000000000000000000000000000000..67fea0e8a1464f8e57f32b22da66b319f5307da6
GIT binary patch
literal 378
zcmZutu};H447D$bT7`;4Vn7Uth&3uIf|&&vnD_+u65Qz2%O$$Iv~((rZ2SZ>zsR*L
zfbd{hPtVWq8Ki3w0Ps-E<83J1&M`FchH=DZl@V!WSXyei?d(PX?BKInR*Ec3t-G4m
z%2TDxQ^SU4bbU#)Z`S!*I@Mp1mu^Xp{eMK<$(;~|b!EBsv=~h7RcFFhr5XDm6$!vm
zj+389L8PZ5hXM*LL=ojLq2M45K>oTP;bs(^FO_M;_;ZIO@PXpDMh=if*&mmXWAYw;
za+F#Q=`L;`@9tv(6NKXk9x^X&6QV3w`oXe`%d{P|S1YLpF0*#n+nzSMtE6^iW_iJu
SP0drk>DiTIry4WmXa5Byu5Yve

literal 0
HcmV?d00001

diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi.rs b/crates/guest-rust/rt/src/wit_bindgen_cabi.rs
new file mode 100644
index 000000000..3ebdc905e
--- /dev/null
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi.rs
@@ -0,0 +1,22 @@
+// This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn cabi_realloc_wit_bindgen_0_41_0(
+    old_ptr: *mut u8,
+    old_len: usize,
+    align: usize,
+    new_len: usize,
+) -> *mut u8 {
+    crate::cabi_realloc(old_ptr, old_len, align, new_len)
+}
+
+static mut WASIP3_TASK: *mut u8 = core::ptr::null_mut();
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn wasip3_task_set_wit_bindgen_0_41_0(ptr: *mut u8) -> *mut u8 {
+    unsafe {
+        let ret = WASIP3_TASK;
+        WASIP3_TASK = ptr;
+        ret
+    }
+}

From 181912bab259f2077d1a76567d91f5c91cb82f33 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Wed, 2 Apr 2025 12:13:36 -0700
Subject: [PATCH 2/6] Refactor with separate objects

Try to work around symbol/export trickery
---
 .github/workflows/main.yml                    |   4 +-
 ci/rebuild-libwit-bindgen-cabi.sh             |  56 +++++++++---------
 .../guest-rust/rt/src/libwit_bindgen_cabi.a   | Bin 628 -> 912 bytes
 crates/guest-rust/rt/src/wit_bindgen_cabi.c   |   7 ++-
 crates/guest-rust/rt/src/wit_bindgen_cabi.o   | Bin 378 -> 414 bytes
 crates/guest-rust/rt/src/wit_bindgen_cabi.rs  |  11 ----
 .../rt/src/wit_bindgen_cabi_realloc.c         |  10 ++++
 .../rt/src/wit_bindgen_cabi_realloc.o         | Bin 0 -> 294 bytes
 .../rt/src/wit_bindgen_cabi_realloc.rs        |  11 ++++
 .../rt/src/wit_bindgen_cabi_wasip3.c          |  12 ++++
 .../rt/src/wit_bindgen_cabi_wasip3.o          | Bin 0 -> 271 bytes
 11 files changed, 69 insertions(+), 42 deletions(-)
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.c
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.o
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.rs
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.c
 create mode 100644 crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.o

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 67a86dd80..185301efe 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -151,10 +151,10 @@ jobs:
     - name: Install wasm32-wasip1 target
       run: rustup target add wasm32-wasip1
 
-    # Verify the output of the `./ci/rebuild-libcabi-realloc.sh` script is
+    # Verify the output of the `./ci/rebuild-libwit-bindgen-cabi.sh` script is
     # up-to-date.
     - uses: ./.github/actions/install-wasi-sdk
-    - run: ./ci/rebuild-libcabi-realloc.sh
+    - run: ./ci/rebuild-libwit-bindgen-cabi.sh
     - run: git diff --exit-code
 
     # Test various feature combinations, make sure they all build
diff --git a/ci/rebuild-libwit-bindgen-cabi.sh b/ci/rebuild-libwit-bindgen-cabi.sh
index 1a903c06b..0caa6b89b 100755
--- a/ci/rebuild-libwit-bindgen-cabi.sh
+++ b/ci/rebuild-libwit-bindgen-cabi.sh
@@ -42,10 +42,11 @@ set -ex
 version=$(./ci/print-current-version.sh | sed 's/\./_/g')
 
 realloc=cabi_realloc_wit_bindgen_$version
-wasip3_task_set=wasip3_task_set_wit_bindgen_$version
-wasip3_task_get=wasip3_task_get_wit_bindgen_$version
 
-cat >./crates/guest-rust/rt/src/wit_bindgen_cabi.rs <<-EOF
+rm -f crates/guest-rust/rt/src/wit_bindgen_*.{rs,o,c}
+rm -f crates/guest-rust/rt/src/libwit_bindgen_cabi.a
+
+cat >./crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.rs <<-EOF
 // This file is generated by $0
 
 #[unsafe(no_mangle)]
@@ -57,20 +58,9 @@ pub unsafe extern "C" fn $realloc(
 ) -> *mut u8 {
     crate::cabi_realloc(old_ptr, old_len, align, new_len)
 }
-
-static mut WASIP3_TASK: *mut u8 = core::ptr::null_mut();
-
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn $wasip3_task_set(ptr: *mut u8) -> *mut u8 {
-    unsafe {
-        let ret = WASIP3_TASK;
-        WASIP3_TASK = ptr;
-        ret
-    }
-}
 EOF
 
-cat >./crates/guest-rust/rt/src/wit_bindgen_cabi.c <<-EOF
+cat >./crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.c <<-EOF
 // This file is generated by $0
 
 #include <stdint.h>
@@ -81,25 +71,37 @@ __attribute__((__weak__, __export_name__("cabi_realloc")))
 void *cabi_realloc(void *ptr, size_t old_size, size_t align, size_t new_size) {
   return $realloc(ptr, old_size, align, new_size);
 }
+EOF
+
+cat >./crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.c <<-EOF
+// This file is generated by $0
 
-extern void *$wasip3_task_set(void *ptr);
+#include <stdlib.h>
+
+static void *WASIP3_TASK = NULL;
 
 __attribute__((__weak__))
 void *wasip3_task_set(void *ptr) {
-  return $wasip3_task_set(ptr);
+  void *ret = WASIP3_TASK;
+  WASIP3_TASK = ptr;
+  return ret;
 }
 EOF
 
-rm -f crates/guest-rust/rt/src/wit_bindgen_cabi.o
-$WASI_SDK_PATH/bin/clang crates/guest-rust/rt/src/wit_bindgen_cabi.c \
-  -O -c -o crates/guest-rust/rt/src/wit_bindgen_cabi.o
+build() {
+  file=$1
+  $WASI_SDK_PATH/bin/clang crates/guest-rust/rt/src/$1.c \
+    -O -c -o crates/guest-rust/rt/src/$1.o
+  # Remove the `producers` section. This appears to differ whether the host for
+  # clang is either macOS or Linux. Not needed here anyway, so discard it to help
+  # either host produce the same object.
+  wasm-tools strip -d producers ./crates/guest-rust/rt/src/$1.o \
+    -o ./crates/guest-rust/rt/src/$1.o
+}
 
-# Remove the `producers` section. This appears to differ whether the host for
-# clang is either macOS or Linux. Not needed here anyway, so discard it to help
-# either host produce the same object.
-wasm-tools strip -d producers ./crates/guest-rust/rt/src/wit_bindgen_cabi.o \
-  -o ./crates/guest-rust/rt/src/wit_bindgen_cabi.o
+build wit_bindgen_cabi_realloc
+build wit_bindgen_cabi_wasip3
 
-rm -f crates/guest-rust/rt/src/libwit_bindgen_cabi.a
 $WASI_SDK_PATH/bin/llvm-ar crus crates/guest-rust/rt/src/libwit_bindgen_cabi.a \
-  crates/guest-rust/rt/src/wit_bindgen_cabi.o
+  crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.o \
+  crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.o
diff --git a/crates/guest-rust/rt/src/libwit_bindgen_cabi.a b/crates/guest-rust/rt/src/libwit_bindgen_cabi.a
index afac3d661f9bd64b0d549812be0aeadf30b22c80..bd13c66e726144821f0cb89722a88544905cba34 100644
GIT binary patch
delta 436
zcmZXQK~BOz7=`~g(~7htG$s;bj8-?|LI|L!%SK!n62xHQa$0ag8lae#NL-a8(BQ_M
z8;;?^t9S+vU<)P^eY^SJ%)IaYU&=H!t*f6ztQIvJ?6exaZ669>I{p5zQy3Ptu{#oN
z*L&znPjsBNE5=UXK2{PddM_Q6FHX#*Y>k{?03t#fwi3od$ZS5#!J195CmASZAhY=7
zCxD=Bz#x-Mn9StHBo^tEPxW1|=XzbX{+diU&GF}<LFzQlGBjT%pqDqbD+QFn?1<HQ
zv3wqV9Eatz(tox!*hs*(z@_(;6(Ww3jxPpsF!Y}pfybN~K-<L*5L%RH3#xrsF=uso
zFrn)j$Rb^d`w}&Nf#(S@BbBnZ%T0-q6ZAwNM_~HB)w*t0#GTcu6DjITau-IS9R!6H
SixF+E_F_B@;yF-K4%#;c*=M8x

delta 259
zcmbQh{)J_NH|stI28MkT1N@kb3??p+V%E#opZL&F!`R$H0Rj@Z7!r$f8G))8`Ir(|
z>Vbf<K7kQPFm*DrOg3S3R8=ZZEY2)2jxR|p&W<lmEr~DBEQwFb%u7j6&5JjPH!+Mi
zU|^hF$f#V;%*4RRF2Kl>oS2juUzD1dlars!z{DlXB*37+puniWq`)lD00a!&TtESV
zMlh4Xjy)$cFFP|Yorz;TNQ9MPDI*iA83GIptjzpq?qCpLWSszXxiD8zD$pW5XKsHN
RR~9A)9!3Un=E*-9y#e*ULdF09

diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi.c b/crates/guest-rust/rt/src/wit_bindgen_cabi.c
index dc274e503..e7cf56f5f 100644
--- a/crates/guest-rust/rt/src/wit_bindgen_cabi.c
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi.c
@@ -1,6 +1,7 @@
 // This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
 
 #include <stdint.h>
+#include <stdlib.h>
 
 extern void *cabi_realloc_wit_bindgen_0_41_0(void *ptr, size_t old_size, size_t align, size_t new_size);
 
@@ -9,9 +10,11 @@ void *cabi_realloc(void *ptr, size_t old_size, size_t align, size_t new_size) {
   return cabi_realloc_wit_bindgen_0_41_0(ptr, old_size, align, new_size);
 }
 
-extern void *wasip3_task_set_wit_bindgen_0_41_0(void *ptr);
+static void *WASIP3_TASK = NULL;
 
 __attribute__((__weak__))
 void *wasip3_task_set(void *ptr) {
-  return wasip3_task_set_wit_bindgen_0_41_0(ptr);
+  void *ret = WASIP3_TASK;
+  WASIP3_TASK = ptr;
+  return ret;
 }
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi.o b/crates/guest-rust/rt/src/wit_bindgen_cabi.o
index 67fea0e8a1464f8e57f32b22da66b319f5307da6..905870b49dd98b81a4804f0324229e28f57e11b9 100644
GIT binary patch
delta 239
zcmX|(F-yZh7>3{PyB?NYpc$<=T&IddIz-$L>mVHzDs;SF%PFC0D!HOK)ycV~&Tjq;
z|Cp1B1)uHV<$ZqmQ*684sSv(=?pRyorFWHG`sJ#6Wza4=-@RXKC?<*qoIpd9W-XGp
z8mLpEjlmiJS&vM;Umir0QW3#Gwb1ZzRHqkt`N-|><|^?;6wlo(x0QEAv6>?RBzIn1
z$e%L1c41+IUlXf|8IEu6GJ9{vBcLU>1o_c4C`o4_q!aT$GjJSLzOJQLx5H~G5R*6&
K5PgCDfJVPJgE#sB

delta 209
zcmbQo{EKOVq*Ny(3v+5-8Gn3yPG(+eVo`i<YHof}B@+X~L?bO#rSin$%mU;1lEmWd
z_~O)(`0~t>_@vCdl=RfRc!PKo!*~M*#)%OY^-Nr{OacrF3<``2ObW~b4M4!a%>@(?
zXaqAE?AU?kXJ_W6GjXg3iLf#(Wn|(>PE5*-FG@|!$;nS<5MW?nW#&h-kwJiwbpj&;
lgD_W7Do~N0v%iZg3ljqmBZD|IgC~DUVo^HKS(9TK9RcynIY0ma

diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi.rs b/crates/guest-rust/rt/src/wit_bindgen_cabi.rs
index 3ebdc905e..126cd2142 100644
--- a/crates/guest-rust/rt/src/wit_bindgen_cabi.rs
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi.rs
@@ -9,14 +9,3 @@ pub unsafe extern "C" fn cabi_realloc_wit_bindgen_0_41_0(
 ) -> *mut u8 {
     crate::cabi_realloc(old_ptr, old_len, align, new_len)
 }
-
-static mut WASIP3_TASK: *mut u8 = core::ptr::null_mut();
-
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn wasip3_task_set_wit_bindgen_0_41_0(ptr: *mut u8) -> *mut u8 {
-    unsafe {
-        let ret = WASIP3_TASK;
-        WASIP3_TASK = ptr;
-        ret
-    }
-}
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.c b/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.c
new file mode 100644
index 000000000..4fa88e67e
--- /dev/null
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.c
@@ -0,0 +1,10 @@
+// This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
+
+#include <stdint.h>
+
+extern void *cabi_realloc_wit_bindgen_0_41_0(void *ptr, size_t old_size, size_t align, size_t new_size);
+
+__attribute__((__weak__, __export_name__("cabi_realloc")))
+void *cabi_realloc(void *ptr, size_t old_size, size_t align, size_t new_size) {
+  return cabi_realloc_wit_bindgen_0_41_0(ptr, old_size, align, new_size);
+}
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.o b/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.o
new file mode 100644
index 0000000000000000000000000000000000000000..c02415fd37c468a323c0cac897e0efcf335fca0d
GIT binary patch
literal 294
zcmZ9HK~BRk5JhK_pthk>EOxBO5-AEQ5;p)AtT@8dF;mN`?Nqi?=&BrnEeGJ9xUfO|
z<<tM8Hz1=!0Kf&Vt78rxi*;GD-#0|oc$R@2yD=OJfD^t_axfHFT01IwHHik}Uo?AK
z(cLYrep{DBnVP^V(Pr{0nbA{{gJs<1Mu9LBxcqwxu)aV6EwtDcZ7JS!;2f@JSz>Fv
zF6N&nQo<Mh8wxo4$S;UGa8|mxe|~tZ5S9o}O_D)#Hei{iz_IFTH`!$N(oWnpZu&9m
bwH*g(W7h=UaA2>vPlp}HZXS*HJ-?-I$mCY`

literal 0
HcmV?d00001

diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.rs b/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.rs
new file mode 100644
index 000000000..126cd2142
--- /dev/null
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi_realloc.rs
@@ -0,0 +1,11 @@
+// This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn cabi_realloc_wit_bindgen_0_41_0(
+    old_ptr: *mut u8,
+    old_len: usize,
+    align: usize,
+    new_len: usize,
+) -> *mut u8 {
+    crate::cabi_realloc(old_ptr, old_len, align, new_len)
+}
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.c b/crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.c
new file mode 100644
index 000000000..2e4a50617
--- /dev/null
+++ b/crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.c
@@ -0,0 +1,12 @@
+// This file is generated by ./ci/rebuild-libwit-bindgen-cabi.sh
+
+#include <stdlib.h>
+
+static void *WASIP3_TASK = NULL;
+
+__attribute__((__weak__))
+void *wasip3_task_set(void *ptr) {
+  void *ret = WASIP3_TASK;
+  WASIP3_TASK = ptr;
+  return ret;
+}
diff --git a/crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.o b/crates/guest-rust/rt/src/wit_bindgen_cabi_wasip3.o
new file mode 100644
index 0000000000000000000000000000000000000000..41f77bd73ac9fe9cd35c333f4c4ae854f8f78df8
GIT binary patch
literal 271
zcmYk0!AiqG7=-8Fq_!qPyjVPl)SD2JOTl~49*Uqs1&`~d{0*VIN!i_0dx{U?EBKzK
zcyVsSe0&U)GX#K6=$(4%#U%yY>=P+<-LSIKuxaf<fC51{BZ{u+il{GeE53%{h6>DZ
z_g7{V#}T1G91c$4X*^iAbyJDS&k+_FA^A|Q-p!>~ZYv#o67gHHTE5KXYq5F+!qN8;
zrSrUWF8?<P;3BfD+jV~b{ICc`a7qZK!~138m95yz4J+SSc3~QsPWyVVbjN98I<HF2
dS*6=jX_qFJH*C3CbLI~_cIm{`Rg>|j{{@9kMV|lw

literal 0
HcmV?d00001


From 29295f76e85272d82d5a1379a8843194a2a8acb5 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Wed, 2 Apr 2025 14:14:20 -0500
Subject: [PATCH 3/6] Update crates/guest-rust/rt/src/async_support/waitable.rs

Co-authored-by: Joel Dice <joel.dice@fermyon.com>
---
 crates/guest-rust/rt/src/async_support/waitable.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/guest-rust/rt/src/async_support/waitable.rs b/crates/guest-rust/rt/src/async_support/waitable.rs
index 2f7dd235d..9b4c4103b 100644
--- a/crates/guest-rust/rt/src/async_support/waitable.rs
+++ b/crates/guest-rust/rt/src/async_support/waitable.rs
@@ -203,7 +203,7 @@ where
         // SAFETY: the contract of `wasip3_task_set` is that the returned
         // pointer is valid for the lifetime of our entire task, so it's valid
         // for this stack frame. Additionally we assert it's non-null to
-        // double-check it's initialized and additionlly check the version for
+        // double-check it's initialized and additionally check the version for
         // the fields that we access.
         //
         // Otherwise the `waitable_unregister` callback should be safe if we

From 04f42534f4991eb387f6f5cd8cc8ebba24f497a2 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Wed, 2 Apr 2025 12:17:14 -0700
Subject: [PATCH 4/6] Update wasi-sdk in  CI

---
 .github/actions/install-wasi-sdk/action.yml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/actions/install-wasi-sdk/action.yml b/.github/actions/install-wasi-sdk/action.yml
index 468e3873a..6132d9965 100644
--- a/.github/actions/install-wasi-sdk/action.yml
+++ b/.github/actions/install-wasi-sdk/action.yml
@@ -5,18 +5,18 @@ runs:
   using: composite
   steps:
     - run: |
-        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-24/wasi-sdk-24.0-x86_64-linux.tar.gz -L | tar xzvf -
-        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-24.0-x86_64-linux" >> $GITHUB_ENV
+        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-25/wasi-sdk-25.0-x86_64-linux.tar.gz -L | tar xzvf -
+        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-25.0-x86_64-linux" >> $GITHUB_ENV
       if: runner.os == 'Linux'
       shell: bash
     - run: |
-        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-24/wasi-sdk-24.0-x86_64-macos.tar.gz -L | tar xzvf -
-        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-24.0-x86_64-macos" >> $GITHUB_ENV
+        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-25/wasi-sdk-25.0-x86_64-macos.tar.gz -L | tar xzvf -
+        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-25.0-x86_64-macos" >> $GITHUB_ENV
       if: runner.os == 'macOS'
       shell: bash
     - run: |
-        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-24/wasi-sdk-24.0-x86_64-windows.tar.gz -L | tar xzvf -
-        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-24.0-x86_64-windows" >> $GITHUB_ENV
+        curl https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-25/wasi-sdk-25.0-x86_64-windows.tar.gz -L | tar xzvf -
+        echo "WASI_SDK_PATH=`pwd`/wasi-sdk-25.0-x86_64-windows" >> $GITHUB_ENV
       if: runner.os == 'Windows'
       shell: bash
     - name: Setup `wasm-tools`

From c0216a145f9c92a52cd176d0764d867871d0196e Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Thu, 3 Apr 2025 08:29:33 -0700
Subject: [PATCH 5/6] Review comments

---
 crates/guest-rust/rt/src/async_support/cabi.rs     | 10 +++++-----
 crates/guest-rust/rt/src/async_support/waitable.rs |  9 +++++++--
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/crates/guest-rust/rt/src/async_support/cabi.rs b/crates/guest-rust/rt/src/async_support/cabi.rs
index 59958da8c..e3afd7a08 100644
--- a/crates/guest-rust/rt/src/async_support/cabi.rs
+++ b/crates/guest-rust/rt/src/async_support/cabi.rs
@@ -12,12 +12,12 @@
 //!   `std::future::Future`.
 //!
 //! Without this module this situation won't work because 0.A.0 has no
-//! knowledge of 0.B.0 meaning that when 0.B.0 decides to block it won't know
-//! where to register its `waitable` within a `waitable-set`.
+//! knowledge of 0.B.0 meaning that 0.B.0 has no means of inserting a `waitable`
+//! into the `waitable-set` managed by 0.A.0's export.
 //!
 //! To solve this problem the long-term intention is that something will live
 //! in `wasi-libc` itself, but in the meantime it's living "somewhere" within
-//! `wit-bindgen 0.*.0`. Specifically all `wit-bindgen` versions will all
+//! `wit-bindgen 0.*.0`. Specifically all `wit-bindgen` versions will
 //! reference, via C linkage, a single function which is used to manipulate a
 //! single pointer in linear memory. This pointer is a `wasip3_task` structure
 //! which has all the various fields to use it.
@@ -50,7 +50,7 @@ extern "C" {
     /// Sets the global task pointer to `ptr` provided. Returns the previous
     /// value.
     ///
-    /// This function acts as both a dual getter and a setter. To get the
+    /// This function acts as a dual getter and a setter. To get the
     /// current task pointer a dummy `ptr` can be provided (e.g. NULL) and then
     /// it's passed back when you're done working with it. When setting the
     /// current task pointer it's recommended to call this and then call it
@@ -85,7 +85,7 @@ pub struct wasip3_task {
     /// well as the `callback_ptr` provided.
     ///
     /// If `waitable` was previously registered with this task then the
-    /// previuos `callback_ptr` is returned. Otherwise `NULL` is returned.
+    /// previous `callback_ptr` is returned. Otherwise `NULL` is returned.
     ///
     /// It's the caller's responsibility to ensure that `callback_ptr` is valid
     /// until `callback` is invoked, `waitable_unregister` is invoked, or
diff --git a/crates/guest-rust/rt/src/async_support/waitable.rs b/crates/guest-rust/rt/src/async_support/waitable.rs
index 9b4c4103b..129151394 100644
--- a/crates/guest-rust/rt/src/async_support/waitable.rs
+++ b/crates/guest-rust/rt/src/async_support/waitable.rs
@@ -206,8 +206,13 @@ where
         // double-check it's initialized and additionally check the version for
         // the fields that we access.
         //
-        // Otherwise the `waitable_unregister` callback should be safe if we
-        // pass a waitable that we own and the task's own pointer.
+        // Otherwise the `waitable_unregister` callback should be safe because:
+        //
+        // * We're fulfilling the contract where the first argument must be
+        //   `(*task).ptr`
+        // * We own the `waitable` that we're passing in, so we're fulfilling
+        //   the contract that arbitrary waitables for other units of work
+        //   aren't being manipulated.
         unsafe {
             let task = cabi::wasip3_task_set(ptr::null_mut());
             assert!(!task.is_null());

From bd50ee294b8dbfb0324aa7d5aa858f4c58f12559 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Thu, 3 Apr 2025 09:06:38 -0700
Subject: [PATCH 6/6] Get crate compiling on native

---
 crates/guest-rust/rt/src/async_support/cabi.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/crates/guest-rust/rt/src/async_support/cabi.rs b/crates/guest-rust/rt/src/async_support/cabi.rs
index e3afd7a08..be9945de9 100644
--- a/crates/guest-rust/rt/src/async_support/cabi.rs
+++ b/crates/guest-rust/rt/src/async_support/cabi.rs
@@ -46,6 +46,7 @@
 
 use core::ffi::c_void;
 
+#[cfg(target_family = "wasm")]
 extern "C" {
     /// Sets the global task pointer to `ptr` provided. Returns the previous
     /// value.
@@ -61,6 +62,12 @@ extern "C" {
     pub fn wasip3_task_set(ptr: *mut wasip3_task) -> *mut wasip3_task;
 }
 
+#[cfg(not(target_family = "wasm"))]
+pub unsafe extern "C" fn wasip3_task_set(ptr: *mut wasip3_task) -> *mut wasip3_task {
+    let _ = ptr;
+    unreachable!();
+}
+
 /// The first version of `wasip3_task` which implies the existence of the
 /// fields `ptr`, `waitable_register`, and `waitable_unregister`.
 pub const WASIP3_TASK_V1: u32 = 1;