From 31777a980e0f4b1b258713158524c0cd9a1dc30f Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Fri, 18 Oct 2019 19:33:20 +0200
Subject: Use execv() to start selected session

Prevent vmchooser from lingering in the background, like a zombie,
haunting you with invisible windows. Also seems to be notably faster
when launching the openbox session.
---
 src/dialog.cpp | 91 +++++++++++++++++++++++-----------------------------------
 1 file changed, 36 insertions(+), 55 deletions(-)

(limited to 'src/dialog.cpp')

diff --git a/src/dialog.cpp b/src/dialog.cpp
index 914448f..dbc4b8e 100644
--- a/src/dialog.cpp
+++ b/src/dialog.cpp
@@ -136,9 +136,11 @@ void Dialog::on_treeView_doubleClicked(const QModelIndex& index)
             return;
 
     // Check preconditions. The method might show error messages and return false
-    if (!s->canRun(true))
+    if (!s->prepareRun())
         return;
 
+    WindowManager::stopOwnInstance(true);
+
     // These two are up here in case run-virt cares...
     if (Config::isSet(Config::PVS)) {
         if (ui->PVS_checkbox->isChecked()) {
@@ -159,62 +161,41 @@ void Dialog::on_treeView_doubleClicked(const QModelIndex& index)
         setenv("VMCHOOSER_DISABLE_SCREENSAVER", "FALSE", 1);
     }
 
-    // Run session
-    if (s->run()) {
-        // Run session start script if the session could be initialized successfully
-        if (QFile::exists(SESSION_START_SCRIPT)) {
-            // Use the current environment variables and add the necessary
-            // information for the startUpScipt.
-            // export session information to the environment of the process to be exec'ed
-            setenv("SESSION_NAME", s->shortDescription().toUtf8(), 1);
-            setenv("SESSION_UUID", s->uuid().toUtf8(), 1);
-            setenv("SESSION_CMD", s->execCommand().toUtf8(), 1);
-            if (s->type() == Session::VSESSION) {
-               setenv("SESSION_TYPE", "VSESSION", 1);
-            } else if (s->type() == Session::XSESSION) {
-               setenv("SESSION_TYPE", "XSESSION", 1);
-            }
-            // Fork this process twice to detach
-            pid_t pid = fork();
-            if (pid == 0) {
-
-                // Close all filedescriptors
-                for (int i = 3; i < 1024; ++i)
-                    ::close(i);
-
-                // Change process group
-                setsid();
-
-                // Reopen standard pipes
-                freopen("/dev/null", "r", stdin);
-                freopen("/dev/null", "w", stdout);
-                freopen("/dev/null", "w", stderr);
-
-                pid = fork();
-                if (pid == 0) {
-                    // At this point we are executing as the 2nd child process
-                    // Replace this clone with the process we'd like to start
-                    char * const args[] = { strdup(VMCHOOSER_SESSION_START_SCRIPT), nullptr };
-                    execv(VMCHOOSER_SESSION_START_SCRIPT, args);
-                }
-                _exit(0); // Dont use exit hooks
-            }
-            // Wait and cleanup the intermediate process
-            waitpid(pid, nullptr, 0);
+    UserConfig::addLastSession(s->uuid().isEmpty() ? s->shortDescription() : s->uuid());
+    UserConfig::setLastTab(activeTab_);
+    UserConfig::setNewsHelpOpen(!ui->helpBox->isHidden());
+    UserConfig::sync();
+
+    QProcess *process = nullptr;
+    if (QFile::exists(SESSION_START_SCRIPT)) {
+        // Companion script
+        process = new QProcess;
+        QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+        env.insert("SESSION_NAME", s->shortDescription());
+        env.insert("SESSION_UUID", s->uuid());
+        env.insert("SESSION_CMD", s->execCommand());
+        if (s->type() == Session::VSESSION) {
+           env.insert("SESSION_TYPE", "VSESSION");
+        } else if (s->type() == Session::XSESSION) {
+           env.insert("SESSION_TYPE", "XSESSION");
         }
-        UserConfig::addLastSession(s->uuid().isEmpty() ? s->shortDescription() : s->uuid());
-        UserConfig::setLastTab(activeTab_);
-        UserConfig::setNewsHelpOpen(!ui->helpBox->isHidden());
-        centerTimer_->stop(); // Stop the auto-center/auto-quit timer, so we don't kill the session :>
-        setVisible(false);
-        // Stopping the window manager has to be done after hiding our window,
-        // or it might still be shown in some Xsessions (e.g. gnome-shell).
-        WindowManager::stopOwnInstance();
-    } else {
-        QMessageBox::critical(
-                    this, trUtf8("vmchooser"),
-                    trUtf8("Vmchooser failed to run the selected session!"));
+        process->setProcessEnvironment(env);
+        process->start(SESSION_START_SCRIPT);
+        process->closeReadChannel(QProcess::StandardError);
+        process->closeReadChannel(QProcess::StandardOutput);
+        process->closeWriteChannel();
     }
+
+    // Run session
+    s->run();
+    // Should not return on success
+    if (process != nullptr) {
+        process->terminate();
+    }
+    QMessageBox::critical(
+                this, trUtf8("vmchooser"),
+                trUtf8("Vmchooser failed to run the selected session!"));
+    QApplication::instance()->quit();
 }
 
 void Dialog::on_treeView_expanded(const QModelIndex& index) {
-- 
cgit v1.2.3-55-g7522