fix: implement child_process IPC (#21490)

This PR implements the Node child_process IPC functionality in Deno on
Unix systems.

For `fd > 2` a duplex unix pipe is set up between the parent and child
processes. Currently implements data passing via the channel in the JSON
serialization format.

2 files changed, 12 insertions, 1 deletions

diff --git a/runtime/js/40_process.js b/runtime/js/40_process.js
index b8e05ce5a..e628aeb4a 100644
--- a/runtime/js/40_process.js
+++ b/runtime/js/40_process.js
@@ -159,6 +159,7 @@ function spawnChildInner(opFn, command, apiName, {
   stderr = "piped",
   signal = undefined,
   windowsRawArguments = false,
+  ipc = -1,
 } = {}) {
   const child = opFn({
     cmd: pathFromURL(command),
@@ -172,6 +173,7 @@ function spawnChildInner(opFn, command, apiName, {
     stdout,
     stderr,
     windowsRawArguments,
+    ipc,
   }, apiName);
   return new ChildProcess(illegalConstructorKey, {
     ...child,
@@ -203,6 +205,12 @@ class ChildProcess {
   #waitPromise;
   #waitComplete = false;
 
+  #pipeFd;
+  // internal, used by ext/node
+  get _pipeFd() {
+    return this.#pipeFd;
+  }
+
   #pid;
   get pid() {
     return this.#pid;
@@ -239,6 +247,7 @@ class ChildProcess {
     stdinRid,
     stdoutRid,
     stderrRid,
+    pipeFd, // internal
   } = null) {
     if (key !== illegalConstructorKey) {
       throw new TypeError("Illegal constructor.");
@@ -246,6 +255,7 @@ class ChildProcess {
 
     this.#rid = rid;
     this.#pid = pid;
+    this.#pipeFd = pipeFd;
 
     if (stdinRid !== null) {
       this.#stdin = writableStreamForRid(stdinRid);
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 0469b38bf..5b4b164a2 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -440,6 +440,7 @@ function bootstrapMainRuntime(runtimeOptions) {
     3: inspectFlag,
     5: hasNodeModulesDir,
     6: maybeBinaryNpmCommandName,
+    7: nodeIpcFd,
   } = runtimeOptions;
 
   performance.setTimeOrigin(DateNow());
@@ -545,7 +546,7 @@ function bootstrapMainRuntime(runtimeOptions) {
   ObjectDefineProperty(globalThis, "Deno", util.readOnly(finalDenoNs));
 
   if (nodeBootstrap) {
-    nodeBootstrap(hasNodeModulesDir, maybeBinaryNpmCommandName);
+    nodeBootstrap(hasNodeModulesDir, maybeBinaryNpmCommandName, nodeIpcFd);
   }
 }