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node: implement node:wasi v26 WASI class surface (+23 tests) - #35709
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cirospaciari wants to merge 15 commits into
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cirospaciari wants to merge 15 commits into
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Rework the node:wasi entry point around Node v26's lib/wasi.js surface,
keeping the existing JS preview1 host functions as the backing engine:
- constructor: options/version/args/env/preopens/stdin/stdout/stderr/
returnOnExit validation with Node's exact error codes and check order;
version is now required ('preview1' or 'unstable')
- start()/initialize()/finalizeBindings()/getImportObject() with Node's
validation messages, ERR_WASI_ALREADY_STARTED on double start, and
returnOnExit (default true) implemented via a thrown sentinel so
start() returns the exit code
- host functions throw ERR_WASI_NOT_STARTED until an instance memory is
attached; failed preopen opens surface as UVWASI_<errno> errors like
uvwasi_init
- module load emits the WASI ExperimentalWarning (suppressed for the
built-in .wasm runner, which promises clean stderr)
Engine fixes found by Node's upstream wasi tests:
- fd_renumber had dup2 backwards: it moved 'to' into 'from' and closed
the freshly opened fd, breaking freopen()
- poll_oneoff wrote 16-byte event records; preview1 events are 32 bytes,
so multi-subscription polls corrupted the guest event array
- poll_oneoff mixed BigInt and Number when charging elapsed time,
throwing on any clock subscription (sleep/nanosleep)
- clock_res_get wrote through a stale/absent DataView; sock_accept was
missing (accept() on a bad fd now reports EBADF)
ERR_INVALID_ARG_TYPE with a single expected string now follows Node's
formatList buckets: 'undefined' renders 'must be undefined', class names
render 'must be an instance of X'. Pre-flattened list strings keep the
legacy 'of type' rendering.
The bun .wasm runner passes version/returnOnExit explicitly and calls
initialize() for reactor modules, preserving its exit-code behavior.
Vendor test/wasi from Node v26.3.0 byte-verbatim, including the wasm fixtures compiled from C, and refresh fixtures/wasi-preview-1.js to the v26 version (the previously vendored copy predated the threads target and parseArgs handling). Add js/node/test/wasi/ to the node-test runner's inclusion predicate; verified with a deliberately failing canary that the directory is collected and executed. Not vendored (fail on Bun): - test-wasi-poll.js: fd readiness (POLLOUT/POLLHUP) needs real poll(2); the JS host over node:fs cannot detect pipe hangup without consuming - test-wasi-pthread.js: wasm shared memory is not enabled in JSC here (WebAssembly.Module rejects shared memories); flaky upstream on Linux - test-wasi-worker-terminate.js: worker.terminate() cannot interrupt a wasm busy-loop, the process wedges and ignores SIGTERM
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…aude/node-wasi # Conflicts: # src/jsc/bindings/ErrorCode.ts
…aude/node-wasi # Conflicts: # src/jsc/bindings/ErrorCode.cpp
- restore src/jsc/bindings/BunHeapProfiler.h (deleted by #36500 on main, still needed by $newCppFunction sites in src/js/node/v8.ts) - web_worker.rs: parent_ref was removed by #36571; deref parent directly - path.rs: re-expose resolve_{posix,windows}_t as pub(crate) for permission.rs - clap: re-expose Diagnostic fields as pub for Arguments.rs node-compat errors - permission.rs: switch std::sync::RwLock -> bun_threading::RwLock, std::env::var -> bun_core::env_var::NODE_OPTIONS (disallowed_types/methods) - run_command.rs: exec_check pub -> pub(crate) (unreachable_pub) - BunHeapProfiler.rs: then(|| ..) -> then_some (unnecessary_lazy_evaluations) - Timer.rs: move SAFETY comment onto the unsafe block it documents
…aude/node-wasi # Conflicts: # src/jsc/bindings/BunHeapProfiler.h
This was referenced Aug 15, 2026
Under --interactive the builtins sit on globalThis as lazy custom-value properties. getOwnPropertyDescriptor materializes each one, which loaded every builtin at REPL startup and let node:wasi print its ExperimentalWarning into sessions that never touched it.
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What this does
Implements Node v26's
node:wasiWASIclass contract on top of Bun's existing JS preview1 host functions, and vendors Node's upstreamtest/wasi/suite. 23 of Node's 26 wasi tests pass verbatim (0 passed before — there was no Node-compatible WASI surface).What changed
src/js/node/wasi.ts— newWASIclass wrapping the existing wasi-js engine, mirroringlib/wasi.jsfrom Node v26.3.0:versionof'preview1'|'unstable',argsarray,env/preopensobjects, int32stdin/stdout/stderr, booleanreturnOnExit) with Node's exact error codes and check orderingstart()/initialize()/finalizeBindings()/getImportObject();_start/_initialize/memoryexport validation with Node's exact messages;ERR_WASI_ALREADY_STARTEDon double startreturnOnExitdefaults to true:proc_exitrecords the code and throws a sentinel WebAssembly can't catch,start()returns the exit codeERR_WASI_NOT_STARTED(wasi.start() has not been called) until instance memory is attachedUVWASI_<errno>/uvwasi_initerrors, matching uvwasi's failure shapeExperimentalWarningon module load, matching Node (suppressed when Bun itself runs a.wasmentry point — the built-in runner promises clean stderr, covered bytest/js/bun/wasm/wasi.test.js)Engine bugs found by the upstream tests (each covered by a vendored test or a new unit test in
test/js/bun/wasm/wasi.test.js):fd_renumberhad dup2 backwards — it movedtointofromand closed the freshly opened fd, breaking wasi-libcfreopen()(test-wasi-io)poll_oneoffwrote 16-byte event records; preview1 events are 32 bytes, so any multi-subscription poll corrupted the guest event array (unit test)poll_oneoffthrewInvalid mix of BigInt and other typeon every clock subscription, breakingsleep()/nanosleep()(unit test)clock_res_getwrote through an absent DataView (test-wasi-clock_getres);sock_acceptwas missing —accept()on a bad fd now reportsEBADF(test-wasi-sock)src/jsc/bindings/ErrorCode.cpp— the single-expected-stringERR_INVALID_ARG_TYPEoverload now follows Node'sformatListbuckets:'undefined'rendersmust be undefined(required by test-wasi-start-validation / test-wasi-initialize-validation), class names rendermust be an instance of X. Pre-flattened"X, Y, or Z"strings keep the legacyof typerendering, so existing list-style call sites are unchanged. No in-repo test asserts the old renderings (grepped).src/js/wasi-runner.js— thebun foo.wasmrunner passesversion: "preview1"andreturnOnExit: falseexplicitly and callsinitialize()for modules without_start, preserving its historical exit-code and stderr behavior.scripts/runner.node.mjs—js/node/test/wasi/added to the node-test inclusion predicate. Verified with a deliberately failing canary that the directory is collected and executed by the runner (then removed the canary), and that a real wasi test passes under the runner.Tests
Vendored byte-verbatim from Node v26.3.0 (
test/wasi/+ wasm fixtures + refreshedfixtures/wasi-preview-1.js): 23 files, all passing CI-style (BUN_GARBAGE_COLLECTOR_LEVEL=1,bunfig.node-test.toml, ASAN debug build). The diff adds 47 files undertest/js/node/test/wasi/: the 23 test files plus the 24.wasmbinaries they load fromwasi/wasm/, which are not tests themselves.test/js/bun/wasm/wasi.test.jsupdated for the requiredversionoption and extended with 2 regression tests for the poll/renumber fixes; all 7 pass.Dropped (fail on Bun, not vendored):
test-wasi-poll.js— fd readiness (POLLOUT / stdin POLLHUP) needs realpoll(2); a JS host overnode:fscannot detect pipe hangup without consuming datatest-wasi-pthread.js— wasm shared memory not enabled in JSC here (WebAssembly.Module doesn't parse: shared memory is not enabled); flaky upstream on Linuxtest-wasi-worker-terminate.js—worker.terminate()cannot interrupt a wasm busy-loop; the process wedges and ignores SIGTERMBehavior notes
new WASI()withoutversionnow throwsERR_INVALID_ARG_TYPE, matching Node ≥20 (previously Bun ignoredversionentirely).test-wasi-options-validation.jsrequires this exact behavior.