feat(wxc_common): add the sandbox execution interfaces (SandboxBackend / SandboxProcess / Runner) by caarlos0 · Pull Request #554 · microsoft/mxc

caarlos0 · 2026-06-24T13:14:29Z

📖 Description

Part 1 of 3 splitting #524 ("mxc-sdk lib crate") into reviewable, compile-ordered PRs. This PR adds the shared, no-pty sandbox execution interfaces to wxc_common that the containment backends and the new library crate build on. It is purely additive — no existing code path uses these yet, so behavior is unchanged.

SandboxProcess — a handle to a running sandboxed child: take_stdin / take_stdout / take_stderr, try_wait, id, kill (process-tree), and wait (drains untaken stdio, honors scriptTimeout), plus stdout/stderr closers for abandoning a backgrounded-descendant-held read without a kill.
SandboxBackend — validate + spawn(request, logger, StdioMode) -> SandboxProcess + a diagnose_exit hook; StdioMode::{Pipes, Inherit}.
Runner<B> — the generic adapter bridging any SandboxBackend to the run-to-completion ScriptRunner (spawn Inherit, then wait).
StreamCloser, group_kill (Unix leader-first SIGKILL of the child's group), and wait_with_timeout (adaptive 1ms→50ms backoff poll).
interruptible_reader (Unix self-pipe + poll) and the Windows pipe helpers in process_util for out-of-band-cancelable streaming reads.
FailurePhase::Timeout so a timeout is distinguishable from other failures.

🔗 References

Splits feat: mxc-sdk lib crate #524. The library backends + executor binaries are migrated onto this surface in Part 2 (unify-backends), and the importable mxc-sdk crate lands in Part 3 (mxc-sdk). Review in that order.

🔍 Validation

cargo test -p wxc_common (macOS, toolchain 1.93): 268 pass.
cargo fmt --all -- --check and cargo clippy --all-targets -- -D warnings clean.
cargo check against x86_64-pc-windows-msvc and x86_64-unknown-linux-gnu; macOS consumer crates (seatbelt_common, mxc_darwin, mxc_pty) build unchanged (additive-safe).

✅ Checklist

Signed the Contributor License Agreement
Linked to an issue
Updated documentation (if applicable)
Updated Copilot instructions (if build, architecture, or conventions changed)

📋 Issue Type

Bug fix
Feature
Task

Microsoft Reviewers: Open in CodeFlow

…d / SandboxProcess / Runner) Introduce the shared, no-pty execution surface that the containment backends and a future in-process library build on. Purely additive: no existing code path uses these yet, so behavior is unchanged. - `SandboxProcess` — a handle to a running sandboxed child: `take_stdin` / `take_stdout` / `take_stderr`, `try_wait`, `id`, `kill` (process-tree), and `wait` (drains any untaken stdio, honors `scriptTimeout`), plus stdout/stderr closers for abandoning a backgrounded-descendant-held read without a kill. - `SandboxBackend` — `validate` + `spawn(request, logger, StdioMode) -> SandboxProcess` + a `diagnose_exit` hook; `StdioMode::{Pipes, Inherit}`. - `Runner<B>` — the generic adapter bridging any `SandboxBackend` to the run-to-completion `ScriptRunner` (spawn `Inherit`, then `wait`). - `StreamCloser`, `group_kill` (Unix leader-first SIGKILL of the child's group), and `wait_with_timeout` (adaptive 1ms->50ms backoff poll). - `interruptible_reader` (Unix self-pipe + `poll`) and the Windows pipe helpers in `process_util` (`InterruptiblePipeReader` / `PipeReadCanceller` / `create_std_pipes`) for out-of-band-cancelable streaming reads. - `FailurePhase::Timeout` so a timeout is distinguishable from other failures. The library backends and executor binaries are migrated onto this surface in a follow-up PR, and the importable `mxc-sdk` crate is built on top of it. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

Copilot

Pull request overview

Adds new cross-backend, handle-based (“streaming”) sandbox execution interfaces to wxc_common as the foundational API layer for follow-up backend unification and the forthcoming mxc-sdk Rust library crate. This is additive scaffolding intended to enable spawning and controlling sandboxed processes without a PTY.

Changes:

Introduces SandboxProcess / SandboxBackend traits plus a generic Runner<B> adapter to bridge to the existing ScriptRunner run-to-completion model.
Adds Unix + Windows primitives for interruptible pipe reads/stdio handling (self-pipe+poll on Unix; CancelIoEx-based cancellation for Windows pipes).
Extends FailurePhase with a dedicated Timeout phase and widens wxc_common’s libc dependency to all Unix targets.

Show a summary per file

File	Description
src/core/wxc_common/src/sandbox_process.rs	New public streaming execution traits/utilities and `Runner<B>` bridge, including Unix timeout polling and group kill helper.
src/core/wxc_common/src/process_util.rs	Adds Windows pipe reader/writer types and an interruptible reader + `StreamCloser` implementation via `CancelIoEx`.
src/core/wxc_common/src/models.rs	Adds `FailurePhase::Timeout` to distinguish timeout termination from normal non-zero exits.
src/core/wxc_common/src/lib.rs	Wires new modules into the crate (`sandbox_process`, `interruptible_reader`) with appropriate platform gating.
src/core/wxc_common/src/interruptible_reader.rs	New Unix interruptible reader using self-pipe + `poll` and a `StreamCloser` canceller.
src/core/wxc_common/Cargo.toml	Expands `libc` dependency from Linux-only to all Unix targets to support new Unix-only modules/helpers.

Copilot's findings

Files reviewed: 6/6 changed files
Comments generated: 3

+/// [`wait`](SandboxProcess::wait), first cancelling its read so the join can't
+/// block. When the stream was drained (a [`spawn_discard`] thread exists), fire


+    // SAFETY: `kill(2)` with a plain pid / negative pgid — just integers.
+    unsafe {
+        libc::kill(pid, libc::SIGKILL); // leader first
+        libc::kill(-pid, libc::SIGKILL); // then its group
+    }
+    Ok(())


+            Err(e) if e.kind() == std::io::ErrorKind::TimedOut => ScriptResponse {
+                exit_code: -1,
+                error_message: format!("script timed out after {}ms", request.script_timeout),
+                failure_phase: FailurePhase::Timeout,
+                ..Default::default()
+            },


This change adapts the Phase 2B strict-wire-model parser to two crates that landed on main after 2B was branched, surfaced when rebasing 2B onto current main: the new in-process `mxc-sdk` library crate (#556) and the `load_request_from_value` entrypoint (#554/#556). Details: - config_parser.rs: port `load_request_from_value` (added on main against the deleted `RawConfig` API) to 2B's wire model — deserialize into `wire::MxcConfig` and call `convert_wire_config`, matching its sibling `load_request_with_options`. - core/mxc-sdk/src/policy.rs: stop emitting `processContainer.name` (the wire `ProcessContainer` is strict and has no `name` field; the id is already carried at top-level `containerId`). Suppress the now-unused `container_id` in the Windows block. - sdk/src/sandbox.ts: likewise stop emitting `processContainer.name`; drop the now-unused `containerId` parameter from `buildProcessBaseContainerConfig`. Tests: - cargo test --workspace -> all pass (the 6 mxc-sdk parse failures from the rejected `name` field are resolved). - cargo fmt --check + cargo clippy --workspace -D warnings -> clean. - schema codegen + corpus (169/169) + schema-version gates -> green. - cd sdk && npm test -> 183 pass. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Generated-with: claude-opus-4.8

Copilot AI review requested due to automatic review settings June 24, 2026 13:14

caarlos0 requested a review from a team as a code owner June 24, 2026 13:14

caarlos0 mentioned this pull request Jun 24, 2026

refactor(backends): unify the library backends on SandboxBackend + route binaries via Runner #555

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7 tasks

Copilot started reviewing on behalf of caarlos0 June 24, 2026 13:15 View session

This was referenced Jun 24, 2026

feat(mxc-sdk): add the importable in-process sandbox library crate #556

Merged

feat: mxc-sdk lib crate #524

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Copilot AI reviewed Jun 24, 2026

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MGudgin approved these changes Jun 24, 2026

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MGudgin merged commit ed7bb1c into microsoft:main Jun 24, 2026
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MGudgin mentioned this pull request Jun 24, 2026

Phase 2B: deserialize the parser into the wire model #566

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feat(wxc_common): add the sandbox execution interfaces (SandboxBackend / SandboxProcess / Runner)#554

feat(wxc_common): add the sandbox execution interfaces (SandboxBackend / SandboxProcess / Runner)#554
MGudgin merged 1 commit into
microsoft:mainfrom
caarlos0:exec-interfaces

caarlos0 commented Jun 24, 2026 •

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		/// [`wait`](SandboxProcess::wait), first cancelling its read so the join can't
		/// block. When the stream was drained (a [`spawn_discard`] thread exists), fire

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📖 Description

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Microsoft Reviewers: Open in CodeFlow

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caarlos0 commented Jun 24, 2026 •

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