child_process: setup stdio on error when possible

As more spawn() errors are classified as runtime errors, it's
no longer appropriate to only check UV_ENOENT when determining
if stdio can be setup. This commit reverses the check to look
for EMFILE and ENFILE specifically.
PR-URL: #27696Fixes: #26852
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: cjihrig

lib/internal/child_process.js

@@ -375,12 +375,11 @@ ChildProcess.prototype.spawn = function(options) {
 err===UV_ENFILE||
 err===UV_ENOENT){
 process.nextTick(onErrorNT,this,err);
+
 // There is no point in continuing when we've hit EMFILE or ENFILE
 // because we won't be able to set up the stdio file descriptors.
-// It's kind of silly that the de facto spec for ENOENT (the test suite)
-// mandates that stdio _is_ set up, even if there is no process on the
-// receiving end, but it is what it is.
-if(err!==UV_ENOENT)returnerr;
+if(err===UV_EMFILE||err===UV_ENFILE)
+returnerr;
 }elseif(err){
 // Close all opened fds on error
 for(i=0;i<stdio.length;i++){

test/parallel/test-child-process-spawn-error.js

@@ -30,6 +30,16 @@ const spawnargs = ['bar'];
 assert.strictEqual(fs.existsSync(enoentPath),false);
 
 constenoentChild=spawn(enoentPath,spawnargs);
+
+// Verify that stdio is setup if the error is not EMFILE or ENFILE.
+assert.notStrictEqual(enoentChild.stdin,undefined);
+assert.notStrictEqual(enoentChild.stdout,undefined);
+assert.notStrictEqual(enoentChild.stderr,undefined);
+assert(Array.isArray(enoentChild.stdio));
+assert.strictEqual(enoentChild.stdio[0],enoentChild.stdin);
+assert.strictEqual(enoentChild.stdio[1],enoentChild.stdout);
+assert.strictEqual(enoentChild.stdio[2],enoentChild.stderr);
+
 enoentChild.on('error',common.mustCall(function(err){
 assert.strictEqual(err.code,'ENOENT');
 assert.strictEqual(err.errno,'ENOENT');

test/sequential/test-child-process-emfile.js

@@ -58,6 +58,12 @@ for (;;) {
 // Should emit an error, not throw.
 constproc=child_process.spawn(process.execPath,['-e','0']);
 
+// Verify that stdio is not setup on EMFILE or ENFILE.
+assert.strictEqual(proc.stdin,undefined);
+assert.strictEqual(proc.stdout,undefined);
+assert.strictEqual(proc.stderr,undefined);
+assert.strictEqual(proc.stdio,undefined);
+
 proc.on('error',common.mustCall(function(err){
 assert.strictEqual(err.code,'EMFILE');
 }));