From 121062d8848986dcfaf421388a5603b3b48a1e58 Mon Sep 17 00:00:00 2001
From: Jani Honkonen <jani.honkonen@digia.com>
Date: Mon, 6 Aug 2012 13:18:48 +0300
Subject: [PATCH] Fix undo and redo in QLineEdit when in password mode

There are some security issues with undo/redo. User should not be
able to get the erased password back in any situation. Therefore
redo must be disabled completely and undo is limited only for erasing
previously entered text.

Task-number: QTBUG-14226
Change-Id: I2b38aca84adbad1c14db76b56ad6303d56b35b4d
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
---
 src/widgets/widgets/qwidgetlinecontrol.cpp    | 22 +++++++
 src/widgets/widgets/qwidgetlinecontrol_p.h    |  4 +-
 .../widgets/qlineedit/tst_qlineedit.cpp       | 66 +++++++++++++++++++
 3 files changed, 90 insertions(+), 2 deletions(-)

diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index 6920354e73b..ba7e2ddacf0 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -1279,6 +1279,13 @@ void QWidgetLineControl::internalUndo(int until)
         return;
     cancelPasswordEchoTimer();
     internalDeselect();
+
+    // Undo works only for clearing the line when in any of password the modes
+    if (m_echoMode != QLineEdit::Normal) {
+        clear();
+        return;
+    }
+
     while (m_undoState && m_undoState > until) {
         Command& cmd = m_history[--m_undoState];
         switch (cmd.type) {
@@ -1868,6 +1875,21 @@ void QWidgetLineControl::processKeyEvent(QKeyEvent* event)
         event->accept();
 }
 
+bool QWidgetLineControl::isUndoAvailable() const
+{
+    // For security reasons undo is not available in any password mode (NoEcho included)
+    // with the exception that the user can clear the password with undo.
+    return !m_readOnly && m_undoState
+            && (m_echoMode == QLineEdit::Normal || m_history[m_undoState - 1].type == QWidgetLineControl::Insert);
+}
+
+bool QWidgetLineControl::isRedoAvailable() const
+{
+    // Same as with undo. Disabled for password modes.
+    return !m_readOnly
+            && m_echoMode == QLineEdit::Normal
+            && m_undoState < m_history.size();
+}
 
 QT_END_NAMESPACE
 
diff --git a/src/widgets/widgets/qwidgetlinecontrol_p.h b/src/widgets/widgets/qwidgetlinecontrol_p.h
index ba3b202bda2..2dce790c1e9 100644
--- a/src/widgets/widgets/qwidgetlinecontrol_p.h
+++ b/src/widgets/widgets/qwidgetlinecontrol_p.h
@@ -125,8 +125,8 @@ public:
         return (c != -1 ? c : 0);
     }
 
-    bool isUndoAvailable() const { return !m_readOnly && m_undoState; }
-    bool isRedoAvailable() const { return !m_readOnly && m_undoState < (int)m_history.size(); }
+    bool isUndoAvailable() const;
+    bool isRedoAvailable() const;
     void clearUndo() { m_history.clear(); m_modifiedState = m_undoState = 0; }
 
     bool isModified() const { return m_modifiedState != m_undoState; }
diff --git a/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp b/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
index 956f970b853..ed53a133e4b 100644
--- a/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
+++ b/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
@@ -287,6 +287,9 @@ private slots:
     void inputMethodQueryImHints_data();
     void inputMethodQueryImHints();
 
+    void undoRedoAndEchoModes_data();
+    void undoRedoAndEchoModes();
+
 protected slots:
     void editingFinished();
 
@@ -3954,5 +3957,68 @@ void tst_QLineEdit::inputMethodQueryImHints()
     QCOMPARE(static_cast<Qt::InputMethodHints>(value.toInt()), hints);
 }
 
+void tst_QLineEdit::undoRedoAndEchoModes_data()
+{
+    QTest::addColumn<int>("echoMode");
+    QTest::addColumn<QStringList>("input");
+    QTest::addColumn<QStringList>("expected");
+
+    QStringList input(QList<QString>() << "aaa" << "bbb" << "ccc");
+
+    QTest::newRow("Normal")
+        << (int) QLineEdit::Normal
+        << input
+        << QStringList(QList<QString>() << "aaa" << "ccc" << "");
+
+    QTest::newRow("NoEcho")
+        << (int) QLineEdit::NoEcho
+        << input
+        << QStringList(QList<QString>() << "" << "" << "");
+
+    QTest::newRow("Password")
+        << (int) QLineEdit::Password
+        << input
+        << QStringList(QList<QString>() << "" << "" << "");
+
+    QTest::newRow("PasswordEchoOnEdit")
+        << (int) QLineEdit::PasswordEchoOnEdit
+        << input
+        << QStringList(QList<QString>() << "" << "" << "");
+}
+
+void tst_QLineEdit::undoRedoAndEchoModes()
+{
+    QFETCH(int, echoMode);
+    QFETCH(QStringList, input);
+    QFETCH(QStringList, expected);
+
+    // create some history for the QLineEdit
+    testWidget->clear();
+    testWidget->setEchoMode(QLineEdit::EchoMode(echoMode));
+    testWidget->insert(input.at(0));
+    testWidget->selectAll();
+    testWidget->backspace();
+    testWidget->insert(input.at(1));
+
+    // test undo
+    QVERIFY(testWidget->isUndoAvailable());
+    testWidget->undo();
+    QCOMPARE(testWidget->text(), expected.at(0));
+    testWidget->insert(input.at(2));
+    testWidget->selectAll();
+    testWidget->backspace();
+    QCOMPARE(testWidget->isUndoAvailable(), echoMode == QLineEdit::Normal);
+    testWidget->undo();
+    QCOMPARE(testWidget->text(), expected.at(1));
+
+    // test redo
+    QCOMPARE(testWidget->isRedoAvailable(), echoMode == QLineEdit::Normal);
+    testWidget->redo();
+    QCOMPARE(testWidget->text(), expected.at(2));
+    QVERIFY(!testWidget->isRedoAvailable());
+    testWidget->redo();
+    QCOMPARE(testWidget->text(), expected.at(2));
+}
+
 QTEST_MAIN(tst_QLineEdit)
 #include "tst_qlineedit.moc"