child_process: close pipe ends that are re-piped

when t0 and t1 are spawned with t0's outputstream [1, 2] is piped into
t1's input, a new pipe is created which uses a copy of the t0's fd.
This leaves the original copy in Node parent, unattended. Net result is
that when t0 produces data, it gets bifurcated into both the copies

Detect the passed handle to be of 'wrap' type and close after the
native spawn invocation by which time piping would have been over.

Fixes: https://github.com/nodejs/node/issues/9413
Fixes: https://github.com/nodejs/node/issues/18016

PR-URL: https://github.com/nodejs/node/pull/21209
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/internal/child_process.js b/lib/internal/child_process.js
index 498dbf6a1c..cb0d8ec6b6 100644
--- a/lib/internal/child_process.js
+++ b/lib/internal/child_process.js
@@ -384,6 +384,12 @@ ChildProcess.prototype.spawn = function(options) {
       continue;
     }
 
+    // stream is already cloned and piped, so close
+    if (stream.type === 'wrap') {
+      stream.handle.close();
+      continue;
+    }
+
     if (stream.handle) {
       // when i === 0 - we're dealing with stdin
       // (which is the only one writable pipe)