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WIP child-process: watch pipe peer close event #62353

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9 changes: 8 additions & 1 deletion lib/internal/child_process.js
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Original file line number Diff line number Diff line change
Expand Up @@ -333,7 +333,14 @@ function flushStdio(subprocess) {


function createSocket(pipe, readable) {
return net.Socket({ handle: pipe, readable });
const socket = net.Socket({ handle: pipe, readable });
if (!readable &&
process.platform !== 'win32' &&
typeof pipe?.watchPeerClose === 'function') {
pipe.watchPeerClose(() => socket.destroy());
socket.once('close', () => pipe.unwatchPeerClose?.());
}
return socket;
}


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99 changes: 99 additions & 0 deletions src/pipe_wrap.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
#include "handle_wrap.h"
#include "node.h"
#include "node_buffer.h"
#include "node_errors.h"
#include "node_external_reference.h"
#include "stream_base-inl.h"
#include "stream_wrap.h"
Expand Down Expand Up @@ -80,6 +81,8 @@ void PipeWrap::Initialize(Local<Object> target,
SetProtoMethod(isolate, t, "listen", Listen);
SetProtoMethod(isolate, t, "connect", Connect);
SetProtoMethod(isolate, t, "open", Open);
SetProtoMethod(isolate, t, "watchPeerClose", WatchPeerClose);
SetProtoMethod(isolate, t, "unwatchPeerClose", UnwatchPeerClose);

#ifdef _WIN32
SetProtoMethod(isolate, t, "setPendingInstances", SetPendingInstances);
Expand Down Expand Up @@ -110,6 +113,8 @@ void PipeWrap::RegisterExternalReferences(ExternalReferenceRegistry* registry) {
registry->Register(Listen);
registry->Register(Connect);
registry->Register(Open);
registry->Register(WatchPeerClose);
registry->Register(UnwatchPeerClose);
#ifdef _WIN32
registry->Register(SetPendingInstances);
#endif
Expand Down Expand Up @@ -159,6 +164,10 @@ PipeWrap::PipeWrap(Environment* env,
// Suggestion: uv_pipe_init() returns void.
}

PipeWrap::~PipeWrap() {
peer_close_watching_ = false;
peer_close_cb_.Reset();

void PipeWrap::Bind(const FunctionCallbackInfo<Value>& args) {
PipeWrap* wrap;
ASSIGN_OR_RETURN_UNWRAP(&wrap, args.This());
Expand Down Expand Up @@ -213,6 +222,96 @@ void PipeWrap::Open(const FunctionCallbackInfo<Value>& args) {
args.GetReturnValue().Set(err);
}

void PipeWrap::WatchPeerClose(const FunctionCallbackInfo<Value>& args) {
PipeWrap* wrap;
ASSIGN_OR_RETURN_UNWRAP(&wrap, args.This());

if (!wrap->IsAlive()) {
return args.GetReturnValue().Set(UV_EBADF);
}

if (wrap->peer_close_watching_) {
return args.GetReturnValue().Set(0);
}

CHECK_GT(args.Length(), 0);
CHECK(args[0]->IsFunction());

Environment* env = wrap->env();
Isolate* isolate = env->isolate();

// Store the JS callback securely so it isn't garbage collected.
wrap->peer_close_cb_.Reset(isolate, args[0].As<Function>());
wrap->peer_close_watching_ = true;

// Start reading to detect EOF/ECONNRESET from the peer.
// We use our custom allocator and reader, ignoring actual data.
int err = uv_read_start(wrap->stream(), PeerCloseAlloc, PeerCloseRead);
if (err != 0) {
wrap->peer_close_watching_ = false;
wrap->peer_close_cb_.Reset();
}
args.GetReturnValue().Set(err);
}

void PipeWrap::UnwatchPeerClose(const FunctionCallbackInfo<Value>& args) {
PipeWrap* wrap;
ASSIGN_OR_RETURN_UNWRAP(&wrap, args.This());

if (!wrap->peer_close_watching_) {
wrap->peer_close_cb_.Reset();
return args.GetReturnValue().Set(0);
}

// Stop listening and release the JS callback to prevent memory leaks.
wrap->peer_close_watching_ = false;
wrap->peer_close_cb_.Reset();
args.GetReturnValue().Set(uv_read_stop(wrap->stream()));
}

void PipeWrap::PeerCloseAlloc(uv_handle_t* handle,
size_t suggested_size,
uv_buf_t* buf) {
// We only care about EOF, not the actual data.
// Using a static 1-byte buffer avoids dynamic memory allocation overhead.
static char scratch;
*buf = uv_buf_init(&scratch, 1);
}

void PipeWrap::PeerCloseRead(uv_stream_t* stream,
ssize_t nread,
const uv_buf_t* buf) {
PipeWrap* wrap = static_cast<PipeWrap*>(stream->data);
if (wrap == nullptr || !wrap->peer_close_watching_) return;

// Ignore actual data reads or EAGAIN (0). We only watch for disconnects.
if (nread > 0 || nread == 0) return;

// Wait specifically for EOF or connection reset (peer closed).
if (nread != UV_EOF && nread != UV_ECONNRESET) return;

// Peer has closed the connection. Stop reading immediately.
wrap->peer_close_watching_ = false;
uv_read_stop(stream);

if (wrap->peer_close_cb_.IsEmpty()) return;
Environment* env = wrap->env();
Isolate* isolate = env->isolate();

// Set up V8 context and handles to safely execute the JS callback.
v8::HandleScope handle_scope(isolate);
v8::Context::Scope context_scope(env->context());
Local<Function> cb = wrap->peer_close_cb_.Get(isolate);
// Reset before calling to prevent re-entrancy issues
wrap->peer_close_cb_.Reset();

errors::TryCatchScope try_catch(env);
try_catch.SetVerbose(true);

// MakeCallback properly tracks AsyncHooks context and flushes microtasks.
wrap->MakeCallback(cb, 0, nullptr);
}

void PipeWrap::Connect(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);

Expand Down
12 changes: 12 additions & 0 deletions src/pipe_wrap.h
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@ class PipeWrap : public ConnectionWrap<PipeWrap, uv_pipe_t> {
SET_SELF_SIZE(PipeWrap)

private:
~PipeWrap() override;
PipeWrap(Environment* env,
v8::Local<v8::Object> object,
ProviderType provider,
Expand All @@ -64,12 +65,23 @@ class PipeWrap : public ConnectionWrap<PipeWrap, uv_pipe_t> {
static void Listen(const v8::FunctionCallbackInfo<v8::Value>& args);
static void Connect(const v8::FunctionCallbackInfo<v8::Value>& args);
static void Open(const v8::FunctionCallbackInfo<v8::Value>& args);
static void WatchPeerClose(const v8::FunctionCallbackInfo<v8::Value>& args);
static void UnwatchPeerClose(const v8::FunctionCallbackInfo<v8::Value>& args);
static void PeerCloseAlloc(uv_handle_t* handle,
size_t suggested_size,
uv_buf_t* buf);
static void PeerCloseRead(uv_stream_t* stream,
ssize_t nread,
const uv_buf_t* buf);

#ifdef _WIN32
static void SetPendingInstances(
const v8::FunctionCallbackInfo<v8::Value>& args);
#endif
static void Fchmod(const v8::FunctionCallbackInfo<v8::Value>& args);

bool peer_close_watching_ = false;
v8::Global<v8::Function> peer_close_cb_;
};


Expand Down
27 changes: 27 additions & 0 deletions test/parallel/test-child-process-stdin-close-event.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
'use strict';

const common = require('../common');
const assert = require('assert');
const { spawn } = require('child_process');

if (common.isWindows) {
common.skip('Not applicable on Windows');
}

const child = spawn(process.execPath, [
'-e',
'require("fs").closeSync(0); setTimeout(() => {}, 2000)',
], { stdio: ['pipe', 'ignore', 'ignore'] });

const timeout = setTimeout(() => {
assert.fail('stdin close event was not emitted');
}, 1000);

child.stdin.on('close', common.mustCall(() => {
clearTimeout(timeout);
child.kill();
}));

child.on('exit', common.mustCall(() => {
clearTimeout(timeout);
}));

Check failure on line 27 in test/parallel/test-child-process-stdin-close-event.js

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