Lots of changes: Two binaries (selection/pw auth), qmake -> cmake, gitignore, more error handling

1. We now have two binaries: One pops up when the print job comes in so you can
select the printer, duplex, copies, etc... The other one pops up when used as
a backend and handles authentication by asking for username and password (WORK
IN PROGRESS!). This is to better handle things like smb printing

2. We use cmake everywhere, and now that we want two binaries it made sense to
switch.

3. Gitignore, well, what to say

4. Show an error message when calling ghostscript for grayscale conversion failed,
insted of just doing nothing and not even closing the GUI.

5. Keep the printergui open for a few seconds after printing, but hide the
window. Later we want to check in the password gui if the printergui is
open to make sure we really should run, and maybe even exchange some information.

12 files changed, 639 insertions, 215 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5f2faeb
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+*.swp
+*~
+build/
+
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..7530b78
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,138 @@
+################################################################################
+# General
+################################################################################
+
+PROJECT(printergui)
+CMAKE_MINIMUM_REQUIRED(VERSION 2.8.0)
+
+# set compiler optimizations for debug and release
+IF (CMAKE_BUILD_TYPE STREQUAL "")
+	SET(CMAKE_BUILD_TYPE Debug)
+ENDIF()
+SET(CMAKE_C_FLAGS_DEBUG "-O0 -g -Wall -Wunused -Wunreachable-code -pedantic")
+SET(CMAKE_C_FLAGS_RELEASE "-O2")
+SET(CMAKE_CXX_FLAGS_DEBUG "-O0 -g -Wall")
+SET(CMAKE_CXX_FLAGS_RELEASE "-O2" )
+
+# local cmake modules
+SET(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
+
+# this command finds libraries and sets all required variables
+FIND_PACKAGE(Qt4 REQUIRED)
+FIND_PACKAGE(Cups REQUIRED)
+
+# some includes
+INCLUDE_DIRECTORIES(
+	${CMAKE_SOURCE_DIR}
+	${CMAKE_BINARY_DIR}
+)
+
+################################################################################
+# Variables
+################################################################################
+
+# printergui (maingui)
+FILE(GLOB MAINGUI_SRCS
+	src/maingui/*.cpp
+)
+
+# password gui (printpwgui
+FILE(GLOB PWGUI_SRCS
+	src/pwgui/*.cpp
+)
+
+################################################################################
+# Qt
+################################################################################
+
+# .ui files
+FILE(GLOB MAINGUI_UIS
+	src/maingui/*.ui
+)
+
+FILE(GLOB PWGUI_UIS
+	src/pwgui/*.ui
+)
+
+# .qrc files
+#SET(MAINGUI_RCS pvsmgr.qrc)
+#SET(PWGUI_RCS pvsclient.qrc)
+
+# includes all header files that should be treated with moc
+SET(MAINGUI_MOC_HDRS
+	src/maingui/printergui.h
+)
+
+SET(PWGUI_MOC_HDRS
+	src/pwgui/pwgui.h
+)
+
+# i18n
+#FILE(GLOB MAINGUI_TSS
+#	i18n/server/*.ts
+#)
+
+#FILE(GLOB PWGUI_TSS
+#	i18n/client/*.ts
+#)
+
+
+# include Qt modules
+#SET(QT_USE_QTDBUS TRUE)
+#SET(QT_USE_QTNETWORK TRUE)
+#SET(QT_USE_QTWEBKIT TRUE)
+
+# add some useful macros and variables
+# (QT_USE_FILE is a variable defined by FIND_PACKAGE( Qt4 ) that contains
+# a path to CMake script)
+INCLUDE(${QT_USE_FILE})
+
+# this will run rcc on .qrc files
+#QT4_ADD_RESOURCES(MAINGUI_RC_SRCS ${MAINGUI_RCS})
+#QT4_ADD_RESOURCES(PWGUI_RC_SRCS ${PWGUI_RCS})
+
+# this will run uic on .ui files
+QT4_WRAP_UI(MAINGUI_UI_HDRS ${MAINGUI_UIS})
+QT4_WRAP_UI(PWGUI_UI_HDRS ${PWGUI_UIS})
+
+# this will run moc
+QT4_WRAP_CPP(MAINGUI_MOC_SRCS ${MAINGUI_MOC_HDRS})
+QT4_WRAP_CPP(PWGUI_MOC_SRCS ${PWGUI_MOC_HDRS})
+
+# i18n, run lupdate and lrelease)
+#QT4_CREATE_TRANSLATION(MAINGUI_QMS ${MAINGUI_SRCS} ${MAINGUI_UI_HDRS} ${MAINGUI_TSS})
+#QT4_CREATE_TRANSLATION(PWGUI_QMS ${PWGUI_SRCS} ${PWGUI_UI_HDRS} ${PWGUI_TSS})
+
+################################################################################
+# Build
+################################################################################
+
+ADD_EXECUTABLE(printergui
+    ${MAINGUI_SRCS}
+    ${MAINGUI_MOC_SRCS}
+    ${MAINGUI_UI_HDRS}
+    ${MAINGUI_RC_SRCS}
+    ${MAINGUI_QMS}
+)
+
+ADD_EXECUTABLE(printpwgui
+    ${PWGUI_SRCS}
+    ${PWGUI_MOC_SRCS}
+    ${PWGUI_UI_HDRS}
+    ${PWGUI_RC_SRCS}
+    ${PWGUI_QMS}
+)
+
+# link
+TARGET_LINK_LIBRARIES(printergui
+    ${QT_LIBRARIES}
+    ${CUPS_LIBRARIES}
+)
+
+TARGET_LINK_LIBRARIES(printpwgui
+    ${QT_LIBRARIES}
+)
+
+# install
+INSTALL(TARGETS printergui printpwgui RUNTIME DESTINATION bin)
+
diff --git a/src/main.cpp b/src/maingui/main.cpp
index a5582d4..f9b8bb2 100644
--- a/src/main.cpp
+++ b/src/maingui/main.cpp
@@ -1,7 +1,8 @@
 #include <QApplication>
 #include <fstream>
-#include "mainwindow.h"
-
+#include "printergui.h"
+#include <fcntl.h>
+#include <sys/stat.h>
 
 int main(int argc, char *argv[])
 {
@@ -10,16 +11,15 @@ int main(int argc, char *argv[])
       return 2;
 
   // Check if file exists
-  std::fstream f;
-  try {
-    f.open(argv[2], std::ios::in);
-  } catch (std::fstream::failure e) {
-    return 3;
+  int fh = open(argv[2], O_RDONLY);
+  if (fh < 0) {
+    fprintf(stderr, "ERROR: Could not open %s for reading..\n", argv[2]);
+	 return 2;
   }
-  f.close();
+  close(fh);
 
   QApplication a(argc, argv);
-  MainWindow w(argv);
+  PrinterGui w(argv);
   w.show();
   return a.exec();
 }
diff --git a/src/mainwindow.cpp b/src/maingui/printergui.cpp
index 4b046d0..3744ffc 100644
--- a/src/mainwindow.cpp
+++ b/src/maingui/printergui.cpp
@@ -1,48 +1,55 @@
-#include "mainwindow.h"
-#include "ui_mainwindow.h"
+#include "printergui.h"
+#include "ui_printergui.h"
 #include <QMessageBox>
-#include <time.h>
+#include <unistd.h>
+#include <QTimer>
 
-#define FIELDLEN 200
-static char _username[FIELDLEN];
-static char _password[FIELDLEN];
-
-static const char * cups_password_cb(const char *prompt)
+// ____________________________________________________________________________
+PrinterGui::PrinterGui(char *argv[], QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::PrinterGui),
+    bgTimeout(-1)
 {
-  char bla[200];
-  snprintf(bla, 200, "/tmp/druckertest-%s-%d", _username, (int)time(NULL));
-  FILE *fh = fopen(bla, "a");
-  if (fh != NULL) {
-    const int passlen = strlen(_password);
-    fprintf(fh, "Drucke mit Authentifizierung als '%s', Passwort mit Länge '%d'\n", _username, passlen);
-    fclose(fh);
+  // When called it is guaranteed that argv has (at least) 3 elements
+
+  // Set username
+  char buf[200];
+  if (getlogin_r(buf, 200) == 0) {
+    // Detect real name
+    this->user = strdup(buf);
+  } else {
+    // Fallback to what command line says
+    this->user = strdup(argv[1]);
   }
-  cupsSetUser(_username);
-  return _password;
-}
 
-// ____________________________________________________________________________
-MainWindow::MainWindow(char *argv[], QWidget *parent) :
-    QMainWindow(parent),
-    ui(new Ui::MainWindow),
-    user(argv[1]),
-    file(argv[2]),
-    authRequired(false) {
+  // Filename
+  this->file = new char[strlen(argv[2]) + 10]; // + 10 in case we rename (ghostscript)
+  strcpy(this->file, argv[2]);
+
   // Initialize cups
   num_dests = cupsGetDests(&dests);
 
   // Initialize UI
   initializeUI();
+
+  // Timer
+  this->bgTimer = new QTimer(this);
+  this->bgTimer->setInterval(1000);
+  connect(bgTimer, SIGNAL(timeout()), this, SLOT(on_bgTimer_timeout()));
 }
 
 // ____________________________________________________________________________
-MainWindow::~MainWindow() {
+PrinterGui::~PrinterGui()
+{
   cupsFreeDests(num_dests, dests);
-  delete ui;
+  free(this->user);
+  delete[] this->file;
+  delete this->ui;
 }
 
 // ____________________________________________________________________________
-void MainWindow::initializeUI() {
+void PrinterGui::initializeUI()
+{
   ui->setupUi(this);
   ui->horizontalLayoutButtons->setAlignment(Qt::AlignRight);
 
@@ -75,15 +82,6 @@ void MainWindow::initializeUI() {
   for (int i = 0; i < 3; ++i)
     ui->printerList->resizeColumnToContents(i);
 
-  // Prefill username
-  if (this->user != NULL) {
-    ui->lineEditUser->setText(QString::fromUtf8(user));
-  }
-
-  // Protect password from being seen
-  ui->lineEditPass->setEchoMode(QLineEdit::Password);
-  ui->lineEditPass->setInputMethodHints(ui->lineEditPass->inputMethodHints() | Qt::ImhNoAutoUppercase);
-
   /*  Main Window properties  */
 
   // Disable close button
@@ -95,7 +93,8 @@ void MainWindow::initializeUI() {
 }
 
 // ____________________________________________________________________________
-void MainWindow::on_printerList_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous) {
+void PrinterGui::on_printerList_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous)
+{
   ui->printerList->setFocus();
 
   cups_dest_t *dest =cupsGetNamedDest(CUPS_HTTP_DEFAULT, current->text(0).toUtf8().constData(), NULL);
@@ -111,26 +110,6 @@ void MainWindow::on_printerList_currentItemChanged(QTreeWidgetItem *current, QTr
     res = ::atoi(type);
   }
 
-  const char *auth = cupsGetOption("auth-info-required", dest->num_options, dest->options);
-  if (auth != NULL && (strstr(auth, "username") != NULL || strstr(auth, "password") != NULL)) {
-    res |= CUPS_PRINTER_AUTHENTICATED;
-  }
-
-  // Check authentication
-  if (res & CUPS_PRINTER_AUTHENTICATED) {
-    ui->labelUser->setEnabled(true);
-    ui->labelPass->setEnabled(true);
-    ui->lineEditUser->setEnabled(true);
-    ui->lineEditPass->setEnabled(true);
-    this->authRequired = true;
-  } else {
-    ui->labelUser->setEnabled(false);
-    ui->labelPass->setEnabled(false);
-    ui->lineEditUser->setEnabled(false);
-    ui->lineEditPass->setEnabled(false);
-    this->authRequired = false;
-  }
-
   // Check color capabilities
   if (res & CUPS_PRINTER_COLOR) {
     ui->comboBoxColor->setEnabled(true);
@@ -167,24 +146,29 @@ void MainWindow::on_printerList_currentItemChanged(QTreeWidgetItem *current, QTr
 }
 
 // ____________________________________________________________________________
-void MainWindow::on_buttonCancel_clicked() {
+void PrinterGui::on_buttonCancel_clicked()
+{
   // Quit with code 1
   QCoreApplication::instance()->exit(1);
 }
 
 // ____________________________________________________________________________
-void MainWindow::on_buttonPrint_clicked() {
+void PrinterGui::on_buttonPrint_clicked()
+{
   QString cmd;
 
   // Wenn Farbe möglich ist. Aber trotzdem Graustufen gewählt
   // Schieb file durch ghostscript
   if (ui->comboBoxColor->isEnabled() && ui->comboBoxColor->currentIndex() == 0) {
     // Run ghostscript to make file grayscale
-    cmd = QString("gs -sDEVICE=psgray -dNOPAUSE -dBATCH -dQUIET -dSAFER  -sOutputFile=\"%22\" \"%1\"").arg(
-                file,
-                file);
-    if (system(cmd.toUtf8().constData()))
-      return; // TODO WARN ABOUT MISSED GS JOB
+    cmd = QString::fromUtf8("gs -sDEVICE=psgray -dNOPAUSE -dBATCH -dQUIET -dSAFER  -sOutputFile=\"%1.conv\" \"%1\"")
+        .arg(QString::fromUtf8(this->file));
+    if (system(cmd.toUtf8().constData())) {
+      QMessageBox::critical(this, "PrinterGUI", "Kann Druckauftrag nicht in Graustufen konvertieren.");
+      return;
+    } else {
+      strcat(this->file, ".conv");
+    }
 
   }
 
@@ -229,15 +213,7 @@ void MainWindow::on_buttonPrint_clicked() {
                                        &(dest->options));
   }
 
-  if (!this->authRequired) {
-    // Only Username
-    cupsSetUser(this->user);
-  } else {
-    // Username + Password
-    snprintf(_username, FIELDLEN, "%s", ui->lineEditUser->text().toUtf8().constData());
-    snprintf(_password, FIELDLEN, "%s", ui->lineEditPass->text().toUtf8().constData());
-    cupsSetPasswordCB(&cups_password_cb);
-  }
+  cupsSetUser(this->user);
 
   // Drucken
   if( 0 == cupsPrintFile(dest->name,
@@ -245,46 +221,23 @@ void MainWindow::on_buttonPrint_clicked() {
                          NULL,
                          dest->num_options,
                          dest->options)) {
-    QMessageBox msgBox;
-    msgBox.setText(cupsLastErrorString());
-    msgBox.exec();
-  } else { // Quit with code 0
-    QCoreApplication::instance()->quit();
+    QMessageBox::critical(this, "CUPS Fehler", cupsLastErrorString());
+  } else {
+    this->bgTimeout = 0;
+    this->hide();
   }
 
 }
 
+void PrinterGui::on_bgTimer_timeout()
+{
+  if (this->bgTimeout == -1) {
+    // Could do something here every second....
+    return;
+  }
+  if (++this->bgTimeout > 4) {
+    // Job was sent, GUI is invisible, quit after a few seconds
+    QCoreApplication::instance()->quit();
+  }
+}
 
-///////////////////////////////  CODE PAPIERKORB  /////////////////////////////
-
-/* * Print via sysctem command * */
-//    // Username, part of whoami source
-//    register uid_t uid = geteuid();
-//    const char *username = getpwuid(uid)->pw_name;
-//    cmd = QString("lp -U %1").arg(username);
-//    // Duplex
-//    if (ui->comboBoxSides->isEnabled())
-//    {
-//        switch (ui->comboBoxSides->currentIndex()){
-//        case 0:
-//            cmd.append(" -o sides=one-sided");
-//            break;
-//        case 1:
-//            cmd.append(" -o sides=two-sided-long-edge");
-//            break;
-//        case 2:
-//            cmd.append(" -o sides=two-sided-long-edge");
-//            break;
-//        }
-//    }
-//    // Kopien
-//    if (ui->lineEditCopies->isEnabled())
-//        cmd.append(QString(" -n %1").arg(ui->lineEditCopies->text()));
-//    // Queue
-//    cmd.append(QString(" -d %1").arg(ui->printerList->currentItem()->text(0)));
-//    // File
-//    cmd.append(QString(" -- \"%1\"").arg(file));
-//    // Print results to stdout
-//    QTextStream (stdout, QIODevice::WriteOnly) << cmd;
-//    // Execute the command
-//    system(cmd.toUtf8().constData());
diff --git a/src/mainwindow.h b/src/maingui/printergui.h
index ec0e4a8..223d787 100644
--- a/src/mainwindow.h
+++ b/src/maingui/printergui.h
@@ -8,30 +8,34 @@
 #include "cups/cups.h"
 
 namespace Ui {
-class MainWindow;
+class PrinterGui;
 }
 
-class MainWindow : public QMainWindow
+class QTimer;
+
+class PrinterGui : public QMainWindow
 {
     Q_OBJECT
 
 public:
-    explicit MainWindow(char *argv[], QWidget *parent = 0);
-    ~MainWindow();
+    explicit PrinterGui(char *argv[], QWidget *parent = 0);
+    ~PrinterGui();
 
 private slots:
     void on_printerList_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous);
     void on_buttonCancel_clicked();
     void on_buttonPrint_clicked();
+    void on_bgTimer_timeout();
 
 private:
-    Ui::MainWindow *ui;
+    Ui::PrinterGui *ui;
     void initializeUI();
     cups_dest_t *dests;
     int num_dests;
-    const char * const user;
-    const char * const file;
-    bool authRequired;
+    char * user;
+    char * file;
+    QTimer * bgTimer;
+    int bgTimeout;
 };
 
 #endif // MAINWINDOW_H
diff --git a/src/mainwindow.ui b/src/maingui/printergui.ui
index 9533e94..8fafd23 100644
--- a/src/mainwindow.ui
+++ b/src/maingui/printergui.ui
@@ -1,17 +1,23 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>MainWindow</class>
- <widget class="QMainWindow" name="MainWindow">
+ <class>PrinterGui</class>
+ <widget class="QMainWindow" name="PrinterGui">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>574</width>
+    <width>590</width>
     <height>286</height>
    </rect>
   </property>
+  <property name="minimumSize">
+   <size>
+    <width>590</width>
+    <height>286</height>
+   </size>
+  </property>
   <property name="windowTitle">
-   <string>Printjob</string>
+   <string>Druckauftrag</string>
   </property>
   <widget class="QWidget" name="centralWidget">
    <layout class="QGridLayout" name="gridLayout">
@@ -34,36 +40,6 @@
       </item>
       <item>
        <layout class="QGridLayout" name="gridLayout_2">
-        <item row="2" column="1">
-         <layout class="QHBoxLayout" name="horizontalLayoutUser">
-          <item>
-           <widget class="QLabel" name="labelUser">
-            <property name="enabled">
-             <bool>false</bool>
-            </property>
-            <property name="text">
-             <string>User:</string>
-            </property>
-            <property name="alignment">
-             <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
-            </property>
-           </widget>
-          </item>
-          <item>
-           <widget class="QLineEdit" name="lineEditUser">
-            <property name="enabled">
-             <bool>false</bool>
-            </property>
-            <property name="sizePolicy">
-             <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-              <horstretch>0</horstretch>
-              <verstretch>0</verstretch>
-             </sizepolicy>
-            </property>
-           </widget>
-          </item>
-         </layout>
-        </item>
         <item row="2" column="0">
          <widget class="QComboBox" name="comboBoxColor">
           <property name="enabled">
@@ -103,36 +79,6 @@
           </item>
          </widget>
         </item>
-        <item row="3" column="1">
-         <layout class="QHBoxLayout" name="horizontalLayoutPass">
-          <item>
-           <widget class="QLabel" name="labelPass">
-            <property name="enabled">
-             <bool>false</bool>
-            </property>
-            <property name="text">
-             <string>Password:</string>
-            </property>
-            <property name="alignment">
-             <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
-            </property>
-           </widget>
-          </item>
-          <item>
-           <widget class="QLineEdit" name="lineEditPass">
-            <property name="enabled">
-             <bool>false</bool>
-            </property>
-            <property name="sizePolicy">
-             <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-              <horstretch>0</horstretch>
-              <verstretch>0</verstretch>
-             </sizepolicy>
-            </property>
-           </widget>
-          </item>
-         </layout>
-        </item>
         <item row="3" column="2">
          <layout class="QHBoxLayout" name="horizontalLayoutButtons">
           <item>
@@ -217,6 +163,32 @@
           </item>
          </layout>
         </item>
+        <item row="2" column="1">
+         <spacer name="horizontalSpacer">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+        <item row="3" column="1">
+         <spacer name="horizontalSpacer_2">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
        </layout>
       </item>
      </layout>
diff --git a/src/printergui.pro b/src/printergui.pro
deleted file mode 100644
index 5b6da93..0000000
--- a/src/printergui.pro
+++ /dev/null
@@ -1,22 +0,0 @@
-#-------------------------------------------------
-#
-# Project created by QtCreator 2013-09-26T00:51:08
-#
-#-------------------------------------------------
-
-QT       += core gui
-
-greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
-
-TARGET = printergui
-TEMPLATE = app
-
-
-SOURCES += main.cpp\
-        mainwindow.cpp
-
-HEADERS  += mainwindow.h
-
-FORMS    += mainwindow.ui
-
-LIBS += -L/usr/lib/x86_64-linux-gnu -lcups
diff --git a/src/pwgui/config.h b/src/pwgui/config.h
new file mode 100644
index 0000000..a06d9db
--- /dev/null
+++ b/src/pwgui/config.h
@@ -0,0 +1,5 @@
+// This is where pwgui will look for backends.
+// Works exactly like /usr/lib/cups/backend, but don't
+// use that as it would cause pwgui invoking itself again...
+#define BACKEND_PATH "/opt/openslx/cups/backend"
+
diff --git a/src/pwgui/main.cpp b/src/pwgui/main.cpp
new file mode 100644
index 0000000..d75f280
--- /dev/null
+++ b/src/pwgui/main.cpp
@@ -0,0 +1,135 @@
+#include "pwgui.h"
+#include "config.h"
+#include <QApplication>
+#include <cups/backend.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define NAMELEN 400
+#define BUFLEN 1000
+
+static int run_backend(char *backend, char *uri, char *jobid, char *user, char *title, char *copies, char *options, char *file, char *password);
+
+int main(int argc, char *argv[])
+{
+  char tmpfile[NAMELEN];
+  char device[NAMELEN];
+  char backend[NAMELEN];
+  int spoolres;
+
+  // Pretty much what smbspool does, but in a generalized way
+  if (argc > 2 && strstr(argv[0], ":/") == NULL && strstr(argv[1], ":/") != NULL) {
+    argv++;
+    argc--;
+   }
+
+  // First check parameter count
+  if (argc != 6 && argc != 7) {
+    fputs("ERROR: Invalid number of arguments passed.\n", stderr);
+    return CUPS_BACKEND_FAILED;
+  }
+
+  if (argc == 6) {
+    // Data comes from stdin, save...
+    snprintf(tmpfile, NAMELEN, "/tmp/print-%s-%d-%s-%d", argv[1], (int)time(NULL), argv[2], (int)getpid());
+    int fh = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0600);
+    if (fh < 0) {
+      fprintf(stderr, "ERROR: Could not open %s for writing..\n", tmpfile);
+      return CUPS_BACKEND_FAILED;
+    }
+    char buffer[BUFLEN];
+    size_t bytes, ret;
+    while (!feof(stdin)) {
+      bytes = fread(buffer, BUFLEN, 1, stdin);
+      if (bytes == 0) break;
+      if ((ret = write(fh, buffer, bytes)) != bytes) {
+        fprintf(stderr, "ERROR: Could not write %d bytes to %s (wrote %d)\n", (int)bytes, tmpfile, (int)ret);
+        remove(tmpfile);
+        return CUPS_BACKEND_FAILED;
+      }
+    }
+    close(fh);
+    //
+  } else {
+    // File given, check if file exists
+    snprintf(tmpfile, NAMELEN, "%s", argv[6]);
+    int fh = open(tmpfile, O_RDONLY);
+    if (fh < 0) {
+      fprintf(stderr, "ERROR: Could not open %s for reading..\n", tmpfile);
+      return CUPS_BACKEND_FAILED;
+    }
+    close(fh);
+    //
+  }
+
+  // Determine device uri
+  char *env = getenv("DEVICE_URI");
+  if (env != NULL && strchr(env, ':') != NULL) {
+    snprintf(device, NAMELEN, "%s", env);
+  } else if (strstr(argv[0], ":/") != NULL)  {
+    snprintf(device, NAMELEN, "%s", argv[0]);
+  } else {
+    fputs("ERROR: No device URI given.\n", stderr);
+    return CUPS_BACKEND_FAILED;
+  }
+
+  // Get backend from uri
+  char *colon = strchr(device, ':');
+  *colon = '\0';
+  snprintf(backend, NAMELEN, "%s/%s", BACKEND_PATH, device);
+  *colon = ':';
+  // Is valid?
+  if (access(backend, X_OK | R_OK) != 0) {
+    fprintf(stderr, "ERROR: Backend %s is not executable.\n", backend);
+    return CUPS_BACKEND_FAILED;
+  }
+
+  // Try right away with what we got
+  spoolres = run_backend(backend, device, argv[1], argv[2], argv[3], argv[4], argv[5], tmpfile, NULL);
+  if (spoolres == CUPS_BACKEND_OK) return spoolres; // Yay
+
+  // Dialog - TODO: Drop privileges here!
+  QApplication a(argc, argv);
+  PwGui w(NULL);
+  w.show();
+  return a.exec();
+  // TODO .....
+}
+
+static int run_backend(char *backend, char *uri, char *jobid, char *user, char *title, char *copies, char *options, char *file, char *password)
+{
+  pid_t pid = fork();
+  if (pid == 0) {
+    // Child
+    if (user != NULL) setenv("AUTH_USERNAME", user, 1);
+    if (password != NULL) setenv("AUTH_PASSWORD", password, 1);
+    char *args[8];
+    args[0] = uri;
+    args[1] = jobid;
+    args[2] = user;
+    args[3] = title;
+    args[4] = copies;
+    args[5] = options;
+    args[6] = file;
+    args[7] = NULL;
+    execv(backend, args);
+    exit(127);
+    return 127;
+  }
+
+  // Main - wait for it...
+  int status;
+  waitpid(pid, &status, 0);
+  if (!WIFEXITED(status)) {
+    fprintf(stderr, "ERROR: Running backend %s failed!\n", backend);
+    return CUPS_BACKEND_FAILED;
+  }
+  return WEXITSTATUS(status);
+}
+
diff --git a/src/pwgui/pwgui.cpp b/src/pwgui/pwgui.cpp
new file mode 100644
index 0000000..31dd822
--- /dev/null
+++ b/src/pwgui/pwgui.cpp
@@ -0,0 +1,59 @@
+#include "pwgui.h"
+#include "ui_pwgui.h"
+#include <QMessageBox>
+#include <QTimer>
+#include <QDesktopWidget>
+
+// ____________________________________________________________________________
+PwGui::PwGui(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::PwGui) {
+  // Initialize UI
+  initializeUI();
+}
+
+// ____________________________________________________________________________
+PwGui::~PwGui() {
+  delete ui;
+}
+
+// ____________________________________________________________________________
+void PwGui::initializeUI() {
+  ui->setupUi(this);
+
+  /*
+  // Prefill username
+  if (this->user != NULL) {
+    ui->lineEditUser->setText(QString::fromUtf8(user));
+  }
+  */
+
+  // Protect password from being seen
+  ui->lineEditPass->setEchoMode(QLineEdit::Password);
+  ui->lineEditPass->setInputMethodHints(ui->lineEditPass->inputMethodHints() | Qt::ImhNoAutoUppercase);
+
+  /*  Main Window properties  */
+
+  // Disable close button
+  this->setWindowFlags((this->windowFlags() & ~Qt::WindowCloseButtonHint) | Qt::WindowStaysOnTopHint);
+  // center dialog on screen center
+  QRect desktopRect = QApplication::desktop()->screenGeometry(this);
+  this->move( desktopRect.width()/2-this->width()/2,
+              desktopRect.height()/2-this->height()/2);
+}
+
+/*
+void PwGui::on_buttonCancel_clicked() {
+  // Quit with code 1
+  QCoreApplication::instance()->exit(1);
+}
+*/
+
+// ____________________________________________________________________________
+void PwGui::on_checkStatusTimer() {
+  static int retries = 0;
+  if (++retries > 20) {
+    QCoreApplication::instance()->quit();
+  }
+}
+
diff --git a/src/pwgui/pwgui.h b/src/pwgui/pwgui.h
new file mode 100644
index 0000000..3e56ec8
--- /dev/null
+++ b/src/pwgui/pwgui.h
@@ -0,0 +1,31 @@
+#ifndef AUTHENTICATION_H
+#define AUTHENTICATION_H
+
+#include <QMainWindow>
+#include <QDebug>
+#include <QTimer>
+
+namespace Ui {
+class PwGui;
+}
+
+class QTimer;
+
+class PwGui : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit PwGui(QWidget *parent = 0);
+    ~PwGui();
+
+private slots:
+    void on_checkStatusTimer();
+
+private:
+    Ui::PwGui *ui;
+    void initializeUI();
+    QTimer* checkStatusTimer;
+};
+
+#endif // AUTHENTICATION_H
diff --git a/src/pwgui/pwgui.ui b/src/pwgui/pwgui.ui
new file mode 100644
index 0000000..236df30
--- /dev/null
+++ b/src/pwgui/pwgui.ui
@@ -0,0 +1,145 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>PwGui</class>
+ <widget class="QMainWindow" name="PwGui">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>310</width>
+    <height>160</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="windowTitle">
+   <string>Drucken - Authentifizierung</string>
+  </property>
+  <widget class="QWidget" name="verticalLayoutWidget">
+   <property name="geometry">
+    <rect>
+     <x>9</x>
+     <y>9</y>
+     <width>291</width>
+     <height>141</height>
+    </rect>
+   </property>
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <layout class="QHBoxLayout" name="horizontalLayout">
+      <item>
+       <widget class="QLabel" name="label">
+        <property name="text">
+         <string>Benutzername</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer name="horizontalSpacer">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+        <property name="sizeHint" stdset="0">
+         <size>
+          <width>40</width>
+          <height>20</height>
+         </size>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="QLineEdit" name="lineEditUser">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <layout class="QHBoxLayout" name="horizontalLayout_3">
+      <item>
+       <widget class="QLabel" name="label_2">
+        <property name="text">
+         <string>Passwort</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer name="horizontalSpacer_2">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+        <property name="sizeHint" stdset="0">
+         <size>
+          <width>40</width>
+          <height>20</height>
+         </size>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="QLineEdit" name="lineEditPass">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <widget class="QLabel" name="labelStatus">
+      <property name="layoutDirection">
+       <enum>Qt::LeftToRight</enum>
+      </property>
+      <property name="frameShape">
+       <enum>QFrame::Panel</enum>
+      </property>
+      <property name="frameShadow">
+       <enum>QFrame::Sunken</enum>
+      </property>
+      <property name="text">
+       <string>Bitte Anmelden</string>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <spacer name="verticalSpacer">
+      <property name="orientation">
+       <enum>Qt::Vertical</enum>
+      </property>
+      <property name="sizeHint" stdset="0">
+       <size>
+        <width>20</width>
+        <height>40</height>
+       </size>
+      </property>
+     </spacer>
+    </item>
+    <item>
+     <layout class="QHBoxLayout" name="horizontalLayout_2">
+      <item>
+       <widget class="QDialogButtonBox" name="buttonBox">
+        <property name="standardButtons">
+         <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+   </layout>
+  </widget>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>