From 804ed1bffb3ad13904a8e8838d63c7adc6e542e7 Mon Sep 17 00:00:00 2001
From: Enrico Forestieri <forenr@lyx.org>
Date: Thu, 27 Sep 2018 21:32:24 +0200
Subject: [PATCH] Fix bug #11210

On Windows, start viewers in detached processes in order to avoid
a crash of the QProcess destructor when their thread terminates.
The opening of a console window is avoided by redirecting to the
null device all standard I/O channels.
---
 src/support/Systemcall.cpp | 27 +++++++++------------------
 status.23x                 |  2 ++
 2 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/src/support/Systemcall.cpp b/src/support/Systemcall.cpp
index 2dbbba7c83..d4f71ffcd9 100644
--- a/src/support/Systemcall.cpp
+++ b/src/support/Systemcall.cpp
@@ -252,23 +252,6 @@ int Systemcall::startscript(Starttype how, string const & what,
 
 	SystemcallPrivate d(infile, outfile, errfile);
 
-#ifdef Q_OS_WIN32
-	// QProcess::startDetached cannot provide environment variables. When the
-	// environment variables are set using the latexEnvCmdPrefix and the process
-	// is started with QProcess::startDetached, a console window is shown every
-	// time a viewer is started. To avoid this, we fall back on Windows to the
-	// original implementation that creates a QProcess object.
-	d.startProcess(cmd, path, lpath, false);
-	if (!d.waitWhile(SystemcallPrivate::Starting, process_events, -1)) {
-		LYXERR0("Systemcall: '" << cmd << "' did not start!");
-		LYXERR0("error " << d.errorMessage());
-		return 10;
-	}
-	if (how == DontWait) {
-		d.releaseProcess();
-		return 0;
-	}
-#else
 	d.startProcess(cmd, path, lpath, how == DontWait);
 	if (how == DontWait && d.state == SystemcallPrivate::Running)
 		return 0;
@@ -279,7 +262,6 @@ int Systemcall::startscript(Starttype how, string const & what,
 		LYXERR0("error " << d.errorMessage());
 		return 10;
 	}
-#endif
 
 	if (!d.waitWhile(SystemcallPrivate::Running, process_events,
 			 os::timeout_min() * 60 * 1000)) {
@@ -370,6 +352,15 @@ void SystemcallPrivate::startProcess(QString const & cmd, string const & path,
 	cmd_ = cmd;
 	if (detached) {
 		state = SystemcallPrivate::Running;
+#ifdef Q_OS_WIN32
+		// Avoid opening a console window when a viewer is started
+		if (in_file_.empty())
+			process_->setStandardInputFile(QProcess::nullDevice());
+		if (out_file_.empty())
+			process_->setStandardOutputFile(QProcess::nullDevice());
+		if (err_file_.empty())
+			process_->setStandardErrorFile(QProcess::nullDevice());
+#endif
 		if (!QProcess::startDetached(toqstr(latexEnvCmdPrefix(path, lpath)) + cmd_)) {
 			state = SystemcallPrivate::Error;
 			return;
diff --git a/status.23x b/status.23x
index 8ff974acf1..9e67c10b80 100644
--- a/status.23x
+++ b/status.23x
@@ -113,6 +113,8 @@ What's new
 
 - Avoid crash when cursor is outside of work area (bug 11296).
 
+- Fix crash on Windows when closing external viewers (bug 11210).
+
 
 
 * USER INTERFACE
-- 
2.39.5