[WASI][Mono] Upgrade WASI SDK / wasmtime / WASIp2 to 0.2.8 and fix sockets for new wasi-libc#128997
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Pull request overview
This PR updates the Mono WASI toolchain (WASI SDK / wasmtime) and regenerates the WASIp2 (0.2.8) component-model bindings used by CoreLib and the WASI HTTP handler. It also updates the WASI socket event loop plumbing to match wasi-libc’s new descriptor-table layout and lazy pollable creation, cleans up obsolete Node.js run scripts, and adjusts tests for unsupported WASI scenarios.
Changes:
- Upgrade toolchain inputs (WASI SDK 33.0, wasmtime 45.0.0) and remove Node-based emulation/run-script generation.
- Regenerate WASIp2 bindings to
0.2.8and update managed call sites accordingly. - Update WASI socket descriptor resolution + pollable subscription (native + managed) and adjust System.Net tests to skip unsupported features on WASI.
Reviewed changes
Copilot reviewed 68 out of 70 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| src/native/libs/System.Native/pal_networking.h | Updates WASI socket descriptor API signature and adds pollable subscription export. |
| src/native/libs/System.Native/pal_networking.c | Implements new WASI descriptor-table probing and lazy pollable subscription helper. |
| src/native/libs/System.Native/entrypoints.c | Exposes the new native entrypoint for managed interop. |
| src/libraries/Common/src/Interop/Wasi/System.Native/Interop.SocketEvent.cs | Updates LibraryImport signatures for the revised native WASI socket APIs. |
| src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketPal.Wasi.cs | Mirrors updated wasi-libc tcp/udp socket struct layouts and removes obsolete descriptor tagged-union types. |
| src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEngine.Wasi.cs | Uses socketType discrimination + lazy pollable subscription to integrate with wasi-libc’s new lazy pollables. |
| src/mono/wasi/wasmtime-version.txt | Bumps the pinned wasmtime version. |
| src/mono/wasi/wasi.proj | Removes obsolete -lwasi-emulated-pthread link flag for WASI SDK 33. |
| src/mono/wasi/build/WasiApp.targets | Updates toolchain version check, removes Node run-script generation, and adjusts link flags. |
| eng/native/gen-buildsys.sh | Removes Node CMAKE_CROSSCOMPILING_EMULATOR usage for WASI. |
| eng/native/gen-buildsys.cmd | Removes Node CMAKE_CROSSCOMPILING_EMULATOR usage for WASI (Windows). |
| eng/AcquireWasiSdk.targets | Bumps acquired WASI SDK version to 33.0. |
| eng/testing/tests.wasi.targets | Forces AppBundle generation for WASI test projects (OutputType=Library). |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/world.wit | Updates WIT imports to WASIp2 0.2.8. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPoll.cs | Updates generated support types for wit-bindgen 0.57.1 output. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiEventLoop.cs | Switches event loop to regenerated 0.2.8 poll/clock APIs. |
| src/libraries/System.Private.CoreLib/src/System/Threading/TimerQueue.Wasi.cs | Updates monotonic clock interop usage to 0.2.8. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/generate-wasi-poll-bindings.sh | Updates binding generation script to fetch 0.2.8 and wit-bindgen 0.57.1. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/generate-wasi-poll-bindings.ps1 | Updates binding generation script to fetch 0.2.8 and wit-bindgen 0.57.1. |
| src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems | Updates compile item list to new generated file names for 0.2.8. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.Imports.wasi.io.v0_2_8.PollImportsInterop.cs | New generated 0.2.8 poll imports interop. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.Imports.wasi.io.v0_2_8.IPollImports.cs | New generated 0.2.8 poll imports API surface. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.Imports.wasi.clocks.v0_2_8.MonotonicClockImportsInterop.cs | New generated 0.2.8 clock imports interop. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.Imports.wasi.clocks.v0_2_8.IMonotonicClockImports.cs | New generated 0.2.8 clock imports API surface. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.imports.wasi.io.v0_2_0.PollInterop.cs | Removes old generated 0.2.0 poll interop. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.imports.wasi.io.v0_2_0.IPoll.cs | Removes old generated 0.2.0 poll API. |
| src/libraries/System.Private.CoreLib/src/System/Threading/Wasi/WasiPollWorld.wit.imports.wasi.clocks.v0_2_0.MonotonicClockInterop.cs | Removes old generated 0.2.0 clock interop. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttp.cs | Updates generated support types for wit-bindgen 0.57.1 output. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpWorld_component_type.wit | Updates WIT package/interface versions from 0.2.0 to 0.2.8. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpHandler.cs | Updates outgoing-handler invocation to regenerated 0.2.8 API surface. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpInterop.cs | Updates conversions and error-code mapping to new generated enum/tag conventions. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiInputStream.cs | Updates stream handling to regenerated 0.2.8 stream error tags. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiOutputStream.cs | Updates stream handling imports to regenerated 0.2.8 API names. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/generate-wasi-http-bindings.sh | Updates binding generation script to fetch 0.2.8 and wit-bindgen 0.57.1. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/generate-wasi-http-bindings.ps1 | Updates binding generation script to fetch 0.2.8 and wit-bindgen 0.57.1. |
| src/libraries/System.Net.Http/src/System.Net.Http.csproj | Updates compile include list to new generated 0.2.8 files. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpWorld.wit.Imports.wasi.io.v0_2_8.* | Adds new generated 0.2.8 io/poll/streams/error interop surfaces. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpWorld.wit.Imports.wasi.http.v0_2_8.* | Adds new generated 0.2.8 http types/outgoing-handler interop surfaces. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpWorld.wit.Imports.wasi.clocks.v0_2_8.* | Adds new generated 0.2.8 clocks interop surfaces. |
| src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpWorld.wit.imports.v0_2_0. | Removes old generated 0.2.0 HTTP/io/clocks interop surfaces. |
| src/libraries/System.Net.Http/tests/FunctionalTests/SocksProxyTest.cs | Skips proxy tests on WASI where handler support is absent. |
| src/libraries/System.Net.Http/tests/FunctionalTests/SocketsHttpHandlerTest.cs | Adds WASI skips for unsupported SocketsHttpHandler scenarios. |
| src/libraries/System.Net.Http/tests/FunctionalTests/ResponseStreamZeroByteReadTests.cs | Skips ConnectCallback scenarios on WASI. |
| src/libraries/System.Net.Http/tests/FunctionalTests/MetricsTest.cs | Marks known-flaky metrics tests as ActiveIssue on WASI. |
| src/libraries/System.Net.Http/tests/FunctionalTests/HttpContentTest.cs | Skips/marks unsupported or flaky scenarios on WASI. |
| src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientTest.cs | Skips unsupported synchronous send / version-selection scenarios on WASI. |
| src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientMiniStressTest.cs | Skips mini-stress scenarios that require System.Net.Security on WASI. |
| src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTestBase.SocketsHttpHandler.cs | Avoids cert-validation callback configuration on WASI. |
| src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.Proxy.cs | Skips proxy tests on WASI handler. |
| src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.Authentication.cs | Skips authentication/preauth tests on WASI handler. |
| src/libraries/System.Net.Sockets/tests/FunctionalTests/SocketAsyncEventArgsTest.cs | Skips DualMode tests on WASI. |
| src/libraries/System.Net.Sockets/tests/FunctionalTests/CreateSocketTests.cs | Skips Socket.Blocking tests on WASI. |
This was referenced Jun 5, 2026
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lewing
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Jun 5, 2026
pavelsavara
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Summary
This branch upgrades the Mono WASI toolchain and regenerates the WASIp2 component-model
bindings against the
0.2.8interfaces. It also fixesSystem.Net.Socketsto work with thenew wasi-libc descriptor-table layout, removes the obsolete Node.js run scripts, and disables
HTTP/socket test scenarios that the WASI handler does not support.
wasi:io,wasi:http,wasi:clocks)Motivation
The
0.2.0snapshot of the WASI SDK and the WASIp2 interfaces had drifted well behind thecurrent ecosystem. wasi-libc also changed its internal socket descriptor table from a tagged
union to a "fat pointer" + vtable design and now creates the embedded pollables lazily, which
broke the existing
System.Net.Socketsevent loop. This brings the toolchain current andrestores socket functionality on the new wasi-libc.
Changes
Toolchain / build infrastructure
eng/AcquireWasiSdk.targets,src/mono/wasi/build/WasiApp.targets: bump expected WASI SDK to33.0. The version check now matches by prefix (StartsWith) so future patch releases of thesame major are accepted.
src/mono/wasi/wasmtime-version.txt: bump wasmtime to45.0.0.eng/native/gen-buildsys.cmd/gen-buildsys.sh: drop the Node.js-basedCMAKE_CROSSCOMPILING_EMULATOR(the--experimental-wasi-unstable-preview1Node path is nolonger used).
src/mono/wasi/wasi.proj,WasiApp.targets: stop linking-lwasi-emulated-pthread, which isno longer provided / needed by WASI SDK 33.0.
Run-script cleanup
WasiApp.targets: remove the_WasmGenerateNodeScriptstarget and the generatednode.mjs/run-node.shfiles. WASI apps run under wasmtime via the existing_GenerateRunWasmtimeScripttarget.Test AppBundle generation
eng/testing/tests.wasi.targets: forceWasmGenerateAppBundle=truefor WASI test projects.Test projects are
OutputType=Library, for which the property defaults tofalse; unlikebrowser there is no SDK that bundles via static web assets, so the in-tree
WasiAppBuildermust run to populate the AppBundle.
Regenerated WASIp2 bindings (
0.2.0→0.2.8)System.Net.Http/.../WasiHttpHandler/*andSystem.Private.CoreLib/.../Threading/Wasi/*:regenerated with wit-bindgen 0.57.1. The new generator changes naming conventions
(
Method.get()→Method.Get(),ErrorCode.DNS_TIMEOUT→ErrorCode.Tags.DnsTimeout,Result.ok/err→Ok/Err,IPoll/ITypes→IPollImports/ITypesImports, etc.).WasiHttpInterop.cs,WasiHttpHandler.cs,WasiInputStream.cs,WasiOutputStream.cs,WasiEventLoop.cs,TimerQueue.Wasi.cs) updated to the new API names..witworld files and thegenerate-wasi-*-bindings.{ps1,sh}scripts updated to pin0.2.8and wit-bindgen0.57.1..csproj/.projitemscompile lists updated to the new generated file names.Sockets on the new wasi-libc descriptor table
wasi-libc replaced the tagged-union descriptor entry with a fat pointer (
{ void* data; descriptor_vtable_t* vtable; }) and now creates the per-socket pollables lazily.src/native/libs/System.Native/pal_networking.c/.h/entrypoints.c:SystemNative_GetWasiSocketDescriptornow returns the descriptordatapointer plus asocketType(1= TCP/stream,2= UDP/datagram) discriminated viagetsockopt(SO_TYPE),since the vtable that previously identified the kind is a private static symbol.
SystemNative_WasiSubscribeSocketPollablelazily calls the wasi-libcsubscribeimports to materialize a pollable handle on demand.
Interop.SocketEvent.cs: matchingLibraryImportsignature updates.SocketPal.Wasi.cs: struct layouts updated to mirror the new wasi-libctcp_socket_t/udp_socket_t(field reorder,bool→byte,error_codewidened toint, trailing timeout fields). The obsoletedescriptor_table_entry_*types are removed.SocketAsyncEngine.Wasi.cs:BeforePollHookdiscriminates on the nativesocketTypeanduses a new
EnsurePollablehelper that subscribes lazily (storing the handle back sowasi-libc owns and later drops it) instead of reading a pre-existing pollable handle.
Test scenario adjustments
System.Net.Httptests: added[SkipOnPlatform(TestPlatforms.Wasi, …)]for scenarios theWASI handler does not support (authentication, pre-authentication, proxy, client/server
certificates, decompression, sync
Send, version selection,MaxConnectionsPerServer,SOCKS proxy, zero-byte read /
ConnectCallback, mini-stress /System.Net.Security,SocketsHttpHandlerargument-validation cases). Several flaky cancellation/metrics cases aremarked
[ActiveIssue(98957, TestPlatforms.Wasi)].System.Net.Socketstests: skipSocket.Blockingand DualMode scenarios unsupported on WASI.