Fix SSH askpass helper text-file-busy race

src/ssh_session_backend.cpp

@@ -4,8 +4,8 @@
 #include <QFile>
 #include <QFileInfo>
 #include <QProcessEnvironment>
-#include <QTemporaryFile>
 #include <QTextStream>
+#include <QUuid>
 
 namespace {
 QString escapeForShellSingleQuotes(const QString& value)
@@ -33,8 +33,7 @@ SshSessionBackend::SshSessionBackend(const Profile& profile, QObject* parent)
       m_connectedProbeTimer(new QTimer(this)),
       m_state(SessionState::Disconnected),
       m_userInitiatedDisconnect(false),
-      m_reconnectPending(false),
-      m_askPassScript(nullptr)
+      m_reconnectPending(false)
 {
     m_connectedProbeTimer->setSingleShot(true);
 
@@ -325,21 +324,26 @@ bool SshSessionBackend::configureAskPass(const SessionConnectOptions& options,
                                          QProcessEnvironment& environment,
                                          QString& error)
 {
+    cleanupAskPassScript();
+
 #ifdef Q_OS_WIN
-    m_askPassScript = new QTemporaryFile(QDir::tempPath() + QStringLiteral("/orbithub_askpass_XXXXXX.cmd"),
-                                         this);
+    m_askPassScriptPath = QDir::temp().filePath(
+        QStringLiteral("orbithub_askpass_%1.cmd")
+            .arg(QUuid::createUuid().toString(QUuid::WithoutBraces)));
 #else
-    m_askPassScript = new QTemporaryFile(QDir::tempPath() + QStringLiteral("/orbithub_askpass_XXXXXX.sh"),
-                                         this);
+    m_askPassScriptPath = QDir::temp().filePath(
+        QStringLiteral("orbithub_askpass_%1.sh")
+            .arg(QUuid::createUuid().toString(QUuid::WithoutBraces)));
 #endif
 
-    if (!m_askPassScript->open()) {
+    QFile script(m_askPassScriptPath);
+    if (!script.open(QIODevice::WriteOnly | QIODevice::Truncate | QIODevice::Text)) {
         error = QStringLiteral("Failed to create temporary askpass helper script.");
         cleanupAskPassScript();
         return false;
     }
 
-    QTextStream out(m_askPassScript);
+    QTextStream out(&script);
 #ifdef Q_OS_WIN
     out << "@echo off\r\n";
     out << "echo " << escapedForWindowsEcho(options.password) << "\r\n";
@@ -348,15 +352,18 @@ bool SshSessionBackend::configureAskPass(const SessionConnectOptions& options,
     out << "printf '%s\\n' '" << escapeForShellSingleQuotes(options.password) << "'\n";
 #endif
     out.flush();
-    m_askPassScript->flush();
-    m_askPassScript->close();
+    script.close();
 
 #ifndef Q_OS_WIN
-    QFile::setPermissions(m_askPassScript->fileName(),
-                          QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner);
+    if (!QFile::setPermissions(m_askPassScriptPath,
+                               QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner)) {
+        error = QStringLiteral("Failed to set permissions on askpass helper script.");
+        cleanupAskPassScript();
+        return false;
+    }
 #endif
 
-    environment.insert(QStringLiteral("SSH_ASKPASS"), m_askPassScript->fileName());
+    environment.insert(QStringLiteral("SSH_ASKPASS"), m_askPassScriptPath);
     environment.insert(QStringLiteral("SSH_ASKPASS_REQUIRE"), QStringLiteral("force"));
     if (!environment.contains(QStringLiteral("DISPLAY"))) {
         environment.insert(QStringLiteral("DISPLAY"), QStringLiteral(":0"));
@@ -367,9 +374,9 @@ bool SshSessionBackend::configureAskPass(const SessionConnectOptions& options,
 
 void SshSessionBackend::cleanupAskPassScript()
 {
-    if (m_askPassScript != nullptr) {
-        delete m_askPassScript;
-        m_askPassScript = nullptr;
+    if (!m_askPassScriptPath.isEmpty()) {
+        QFile::remove(m_askPassScriptPath);
+        m_askPassScriptPath.clear();
     }
 }
 
@@ -402,6 +409,9 @@ QString SshSessionBackend::mapSshError(const QString& rawError) const
     if (raw.contains(QStringLiteral("No such file or directory"), Qt::CaseInsensitive)) {
         return QStringLiteral("Required file was not found.");
     }
+    if (raw.contains(QStringLiteral("Text file busy"), Qt::CaseInsensitive)) {
+        return QStringLiteral("Credential helper could not start (text file busy). Retry the connection.");
+    }
     if (raw.isEmpty()) {
         return QStringLiteral("SSH connection failed for an unknown reason.");
     }

src/ssh_session_backend.h

@@ -7,8 +7,6 @@
 #include <QString>
 #include <QTimer>
 
-class QTemporaryFile;
-
 class SshSessionBackend : public SessionBackend
 {
     Q_OBJECT
@@ -37,7 +35,7 @@ private:
     bool m_reconnectPending;
     SessionConnectOptions m_reconnectOptions;
     QString m_lastRawError;
-    QTemporaryFile* m_askPassScript;
+    QString m_askPassScriptPath;
 
     void setState(SessionState state, const QString& message);
     bool startSshProcess(const SessionConnectOptions& options);