QProcess/Unix: fix close() on invalid file descriptor

Commit 90bc0ad41f9937f9cba801b3166635f6f55e0678 ("QProcess/Unix: add
failChildProcessModifier()") added this line that set childStartedPipe
so that the failChildProcess() callback had something to write to. But
we left it set on exit from QProcessPrivate::startDetached(), which
caused the QProcess destructor to try and close it.

Noticed when debugging the issue for QTBUG-123083.

Pick-to: 6.7 6.7.0
Task-number: QTBUG-123083
Change-Id: I6818d78a57394e37857bfffd17bbc41c8400270f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index ca65a3c776..fcbce92ade 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -1290,7 +1290,6 @@ void QProcessPrivate::waitForDeadChild()
 bool QProcessPrivate::startDetached(qint64 *pid)
 {
     AutoPipe startedPipe, pidPipe;
-    childStartedPipe[1] = startedPipe[1];
     if (!startedPipe || !pidPipe) {
         setErrorAndEmit(QProcess::FailedToStart, "pipe: "_L1 + qt_error_string(errno));
         return false;
@@ -1309,6 +1308,7 @@ bool QProcessPrivate::startDetached(qint64 *pid)
         return false;
     }
 
+    childStartedPipe[1] = startedPipe[1];   // for failChildProcess()
     pid_t childPid = childProcess.doFork([&] {
         ::setsid();
 
@@ -1323,6 +1323,7 @@ bool QProcessPrivate::startDetached(qint64 *pid)
         qt_safe_write(pidPipe[1], &doubleForkPid, sizeof(pid_t));
         return 0;
     });
+    childStartedPipe[1] = -1;
 
     int savedErrno = errno;
     closeChannels();