cups: Show a dialog when asked for password

Otherwise the default cups implementation is used, that is,
asking for the password on the command line,
which is probably not what our users expect.

Change-Id: Ib563d542fee71c13ed23b1a99fbe06a7d4d4eadf
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 72 insertions, 0 deletions

diff --git a/src/plugins/printsupport/cups/qcupsprintersupport.cpp b/src/plugins/printsupport/cups/qcupsprintersupport.cpp
index a9c992a2e1..56191c4dec 100644
--- a/src/plugins/printsupport/cups/qcupsprintersupport.cpp
+++ b/src/plugins/printsupport/cups/qcupsprintersupport.cpp
@@ -47,6 +47,13 @@
 
 #include <QtPrintSupport/QPrinterInfo>
 
+#include <QGuiApplication>
+#include <QDialog>
+#include <QDialogButtonBox>
+#include <QFormLayout>
+#include <QLabel>
+#include <QLineEdit>
+
 #include <cups/ppd.h>
 #ifndef QT_LINUXBASE // LSB merges everything into cups.h
 # include <cups/language.h>
@@ -54,9 +61,74 @@
 
 QT_BEGIN_NAMESPACE
 
+static const char *getPasswordCB(const char */*prompt*/, http_t *http, const char */*method*/, const char *resource, void */*user_data*/)
+{
+    // cups doesn't free the const char * we return so keep around
+    // the last password so we don't leak memory if called multiple times.
+    static QByteArray password;
+
+    // prompt is always "Password for %s on %s? " but we can't use it since we allow the user to change the user.
+    // That is fine because cups always calls cupsUser after calling this callback.
+    // We build our own prompt with the hostname (if not localhost) and the resource that is being used
+
+    char hostname[HTTP_MAX_HOST];
+    httpGetHostname(http, hostname, HTTP_MAX_HOST);
+
+    const QString username = QString::fromLocal8Bit(cupsUser());
+
+    QDialog dialog;
+    dialog.setWindowTitle(QCoreApplication::translate("QCupsPrinterSupport", "Authentication Needed"));
+
+    QFormLayout *layout = new QFormLayout(&dialog);
+    layout->setSizeConstraint(QLayout::SetFixedSize);
+
+    QLineEdit *usernameLE = new QLineEdit();
+    usernameLE->setText(username);
+
+    QLineEdit *passwordLE = new QLineEdit();
+    passwordLE->setEchoMode(QLineEdit::Password);
+
+    QString resourceString = QString::fromLocal8Bit(resource);
+    if (resourceString.startsWith(QStringLiteral("/printers/")))
+        resourceString = resourceString.mid(QStringLiteral("/printers/").length());
+
+    QLabel *label = new QLabel();
+    if (hostname == QStringLiteral("localhost")) {
+        label->setText(QCoreApplication::translate("QCupsPrinterSupport", "Authentication needed to use %1.").arg(resourceString));
+    } else {
+        label->setText(QCoreApplication::translate("QCupsPrinterSupport", "Authentication needed to use %1 on %2.").arg(resourceString).arg(hostname));
+        label->setWordWrap(true);
+    }
+
+    layout->addRow(label);
+    layout->addRow(new QLabel(QCoreApplication::translate("QCupsPrinterSupport", "Username:")), usernameLE);
+    layout->addRow(new QLabel(QCoreApplication::translate("QCupsPrinterSupport", "Password:")), passwordLE);
+
+    QDialogButtonBox *buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
+    layout->addRow(buttonBox);
+
+    QObject::connect(buttonBox, &QDialogButtonBox::accepted, &dialog, &QDialog::accept);
+    QObject::connect(buttonBox, &QDialogButtonBox::rejected, &dialog, &QDialog::reject);
+
+    passwordLE->setFocus();
+
+    if (dialog.exec() != QDialog::Accepted)
+        return nullptr;
+
+    if (usernameLE->text() != username)
+        cupsSetUser(usernameLE->text().toLocal8Bit().constData());
+
+    password = passwordLE->text().toLocal8Bit();
+
+    return password.constData();
+}
+
 QCupsPrinterSupport::QCupsPrinterSupport()
     : QPlatformPrinterSupport()
 {
+    // Only show password dialog if GUI application
+    if (qobject_cast<QGuiApplication*>(QCoreApplication::instance()))
+        cupsSetPasswordCB2(getPasswordCB, nullptr /* user_data */ );
 }
 
 QCupsPrinterSupport::~QCupsPrinterSupport()