[WSLC] Generate WSLC SDK FFI bindings with bindgen by SohamDas2021 · Pull Request #669 · microsoft/mxc

Soham Das (SohamDas2021) · 2026-07-22T18:32:38Z

📖 Description

Replaces the hand-written WSLC SDK FFI bindings with bindgen-generated bindings so any ABI drift between the SDK headers and our Rust declarations becomes a compile error instead of silent undefined behavior at runtime.

🔗 References

🔍 Validation

✅ Checklist

Signed the Contributor License Agreement
Linked to an issue
Updated documentation (if applicable)
Updated Copilot instructions (if build, architecture, or conventions changed)
If this PR changes Cargo.lock, the dependency-feed-check check passes (see docs/pull-requests.md)

📋 Issue Type

Bug fix
Feature
Task

GitHub Actions runs the PR validation build automatically. The ADO pipeline
(MXC-PR-Build) is the Azure version of the PR pipeline, kept in parity with the GitHub
Actions build; it runs on merge to main, and Microsoft reviewers with write access can trigger it
on a PR with /azp run. See docs/pull-requests.md.

If the dependency-feed-check check fails on a new dependency, the crate must be added to
the feed before the PR can pass. See docs/pull-requests.md
for the steps.

Microsoft Reviewers: Open in CodeFlow

azure-pipelines · 2026-07-22T18:32:47Z

Azure Pipelines: There may be pipelines that require an authorized user to comment /azp run to run.

Copilot

Pull request overview

This PR migrates the WSLC backend’s Rust FFI surface from hand-written declarations to bindgen-generated bindings, so ABI drift between the pinned WSLC SDK header (wslcsdk.h) and our Rust types/signatures is caught at compile time rather than becoming silent runtime UB.

Changes:

Add and commit bindgen-generated WSLC SDK bindings (wslcsdk_sys.rs) plus a PowerShell regeneration script.
Refactor wslc_bindings.rs into a thin façade over the generated module (DLL anti-hijack load + required-symbol validation + RAII guards).
Update the WSLC runner + policy mapping and add documentation/runbook for maintaining the bindings.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/backends/wslc/common/src/wslcsdk_sys.rs	New bindgen-generated ABI surface + dynamic-loading `WslcSdk` table (committed artifact).
src/backends/wslc/common/src/wslc_bindings.rs	Façade over generated bindings: safe-ish `load()`, required-export validation, RAII guards, `S_OK`, helpers.
src/backends/wslc/common/src/wsl_container_runner.rs	Update call sites/struct field names/enum constants and callback ABI to match bindgen output.
src/backends/wslc/common/src/policy_mapping.rs	Update networking mode mapping/tests to use bindgen newtype constants.
src/backends/wslc/common/src/lib.rs	Export new `wslcsdk_sys` module.
scripts/generate-wslc-bindings.ps1	New standalone regeneration script (bindgen CLI + libclang + MSVC/WinSDK include discovery + header extraction from `.nupkg`).
docs/wsl/wslc-sdk-bindings.md	New runbook documenting the generated file, why it’s committed, and how to bump/regenerate safely.
docs/wsl/wsl-container-getting-started.md	Link to the new bindings-maintenance documentation.
.github/copilot-instructions.md	Document the bindgen-generated WSLC bindings convention and regeneration procedure.

+        let mut missing = WslcComponentFlags::WSLC_COMPONENT_FLAG_NONE;
+        let hr = sdk.WslcGetMissingComponents(&mut missing);
        if hr != S_OK {
            return Err(sdk_error("WslcGetMissingComponents failed", hr, ""));
        }


azure-pipelines · 2026-07-22T18:55:36Z

Azure Pipelines: There may be pipelines that require an authorized user to comment /azp run to run.

Copilot

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

+$nupkg = Get-ChildItem $vendorDir -Filter "*.nupkg" | Sort-Object Name -Descending | Select-Object -First 1
+if (-not $nupkg) { Fail "No vendored .nupkg found in '$vendorDir'." }


+if ($cmd) { $bindgen = $cmd.Source }
+if (-not $bindgen) { $bindgen = Join-Path $env:USERPROFILE ".cargo\bin\bindgen.exe" }
+if (-not (Test-Path $bindgen)) {
+    Fail "bindgen CLI not found. Install it with: cargo install bindgen-cli"


Copilot

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

+$verLine = Select-String -Path (Join-Path $wslcCommon "build.rs") -Pattern 'WSLC_SDK_VERSION\s*:\s*&str\s*=\s*"([^"]+)"' | Select-Object -First 1
+if (-not $verLine) { Fail "Could not read WSLC_SDK_VERSION from build.rs." }
+$wslcVersion = $verLine.Matches[0].Groups[1].Value
+$nupkgPath = Join-Path $vendorDir "Microsoft.WSL.Containers.$wslcVersion.nupkg"


Copilot

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.

Branden Bonaby (bbonaby) · 2026-07-27T23:08:11Z

 /// on drop), so the pointer remains valid for the duration of all callbacks.
 /// The SDK guarantees `data` is valid for `data_size` bytes during the callback.
-unsafe extern "system" fn io_callback(
+unsafe extern "C" fn io_callback(


ah it's a bindgen thing. If you don't believe in your testing it'll cause an issue then I'm all good. For what it's worth looks like we can override what bindgen outputs via the override_abi parameter to its builder. That said I think from reading through the docs it's only useful if we expect to run things on x86 systems.

Integrates the bindgen-generated WSLC FFI bindings (microsoft#669) with this branch's Rust SDK work. Both sides changed `wslc_bindings.rs` and `wsl_container_runner.rs` heavily, but with complementary intent, so the resolution keeps both: - `wslc_bindings.rs` takes upstream's facade over the generated `wslcsdk_sys`, and re-applies this branch's additions on top: the `ComApartment` COM guard, `is_available()` behind `platform_support()`, and the removal of the debug `eprintln!`s from the RAII guards' `Drop`. - `wsl_container_runner.rs` keeps this branch's restructured lifecycle (`start_container` / `StartedContainer` / `IoSink` / streaming) and ports every SDK call site to the generated API shape: `(sdk.Fn)(..)` becomes `sdk.Fn(..)`, the guards take `sdk.release_*_fn()`, enum variants and struct fields take bindgen's C-style names, and the callbacks become `extern "C"`. - `lib.rs` keeps both module sets. This branch's "never unload `wslcsdk.dll`" safety property survived the change of ownership: bindgen's dynamic-loading `WslcSdk` owns its `Library`, so the leak moves up into `WslcSdk::shared()`, a process-wide `OnceLock` instance handed out as `&'static`. That also resolves the review comment noting the previous claim was wrong — the module really is loaded and symbol-checked once now — and removes `sdk` from `StartedContainer`'s drop-order reasoning entirely, since it is a borrow rather than an owned handle. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 98f4724a-151d-4e38-9367-52048ffcdb5d Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

Soham Das (SohamDas2021) added 2 commits July 22, 2026 11:22

Generate WSLC SDK FFI bindings with bindgen

fbdab56

Restore fail-fast symbol validation in WslcSdk::load

36c85e5

Copilot AI review requested due to automatic review settings July 22, 2026 18:32

Copilot started reviewing on behalf of Soham Das (SohamDas2021) July 22, 2026 18:33 View session

Copilot AI reviewed Jul 22, 2026

View reviewed changes

Addressed PR comments

2f20e81

Soham Das (SohamDas2021) marked this pull request as ready for review July 22, 2026 18:55

Soham Das (SohamDas2021) requested a review from a team as a code owner July 22, 2026 18:55

Branden Bonaby (bbonaby) reviewed Jul 27, 2026

View reviewed changes

Addressed PR comments

bf8677b

Copilot AI review requested due to automatic review settings July 27, 2026 19:01

Copilot started reviewing on behalf of Soham Das (SohamDas2021) July 27, 2026 19:01 View session

Copilot AI reviewed Jul 27, 2026

View reviewed changes

Address more comments

5defcfc

Copilot AI review requested due to automatic review settings July 27, 2026 19:15

Copilot started reviewing on behalf of Soham Das (SohamDas2021) July 27, 2026 19:15 View session

Copilot AI reviewed Jul 27, 2026

View reviewed changes

Soham Das (SohamDas2021) requested review from Branden Bonaby (bbonaby) and Copilot July 27, 2026 22:42

Copilot started reviewing on behalf of Soham Das (SohamDas2021) July 27, 2026 22:42 View session

Copilot AI reviewed Jul 27, 2026

View reviewed changes

Branden Bonaby (bbonaby) approved these changes Jul 27, 2026

View reviewed changes

Soham Das (SohamDas2021) merged commit 61af417 into main Jul 27, 2026
24 checks passed

Soham Das (SohamDas2021) deleted the user/sodas/wslc-bindgen branch July 27, 2026 23:26

Carlos Alexandro Becker (caarlos0) mentioned this pull request Jul 28, 2026

Make WSLC an available backend on the Rust SDK #687

Merged

8 tasks

Copilot AI mentioned this pull request Jul 28, 2026

[WSLC] Add cooperative HTTP/HTTPS proxy support #652

Merged

8 tasks

Navigation Menu

Uh oh!

[WSLC] Generate WSLC SDK FFI bindings with bindgen - #669

[WSLC] Generate WSLC SDK FFI bindings with bindgen#669
Soham Das (SohamDas2021) merged 5 commits into
mainfrom
user/sodas/wslc-bindgen

Soham Das (SohamDas2021) commented Jul 22, 2026 •

edited by microsoft-github-policy-service Bot

Loading

Uh oh!

azure-pipelines Bot commented Jul 22, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

azure-pipelines Bot commented Jul 22, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI left a comment

Uh oh!

Branden Bonaby (bbonaby) Jul 27, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

		$nupkg = Get-ChildItem $vendorDir -Filter "*.nupkg" \| Sort-Object Name -Descending \| Select-Object -First 1
		if (-not $nupkg) { Fail "No vendored .nupkg found in '$vendorDir'." }

Uh oh!

Conversation

Soham Das (SohamDas2021) commented Jul 22, 2026 • edited by microsoft-github-policy-service Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📖 Description

🔗 References

🔍 Validation

✅ Checklist

📋 Issue Type

Microsoft Reviewers: Open in CodeFlow

Uh oh!

azure-pipelines Bot commented Jul 22, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

azure-pipelines Bot commented Jul 22, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Branden Bonaby (bbonaby) Jul 27, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Soham Das (SohamDas2021) commented Jul 22, 2026 •

edited by microsoft-github-policy-service Bot

Loading