QWindowsPrintDevice: Handle return value of DocumentProperties correctly

If the return value is less than 0 which signifies an error then trying
to malloc that will cause an exception.

Change-Id: Ia0153d4cb7aac1dacb509280b45be149a093b7c4
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 68 insertions, 88 deletions

diff --git a/src/plugins/printsupport/windows/qwindowsprintdevice.cpp b/src/plugins/printsupport/windows/qwindowsprintdevice.cpp
index d378ff3130..98978f4bbe 100644
--- a/src/plugins/printsupport/windows/qwindowsprintdevice.cpp
+++ b/src/plugins/printsupport/windows/qwindowsprintdevice.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2014 John Layt <jlayt@kde.org>
+** Copyright (C) 2016 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the plugins of the Qt Toolkit.
@@ -74,6 +75,22 @@ static QPrint::InputSlot paperBinToInputSlot(int windowsId, const QString &name)
     return slot;
 }
 
+static LPDEVMODE getDevmode(HANDLE hPrinter, const QString &printerId)
+{
+    LPWSTR printerIdUtf16 = const_cast<LPWSTR>(reinterpret_cast<LPCWSTR>(printerId.utf16()));
+    // Allocate the required DEVMODE buffer
+    LONG dmSize = DocumentProperties(NULL, hPrinter, printerIdUtf16, NULL, NULL, 0);
+    if (dmSize < 0)
+        return Q_NULLPTR;
+    LPDEVMODE pDevMode = reinterpret_cast<LPDEVMODE>(malloc(dmSize));
+     // Get the default DevMode
+    LONG result = DocumentProperties(NULL, hPrinter, printerIdUtf16, pDevMode, NULL, DM_OUT_BUFFER);
+    if (result != IDOK) {
+        free(pDevMode);
+        pDevMode = Q_NULLPTR;
+    }
+    return pDevMode;
+}
 
 QWindowsPrintDevice::QWindowsPrintDevice()
     : QPlatformPrintDevice(),
@@ -191,26 +208,21 @@ QPageSize QWindowsPrintDevice::defaultPageSize() const
 
     QPageSize pageSize;
 
-    // Allocate the required DEVMODE buffer
-    DWORD dmSize = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), NULL, NULL, 0);
-    LPDEVMODE pDevMode = (LPDEVMODE)malloc(dmSize);
-
-     // Get the default DevMode
-    DWORD result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), pDevMode, NULL, DM_OUT_BUFFER);
-
-    // Get the default paper size
-    if (result == IDOK && pDevMode->dmFields & DM_PAPERSIZE) {
-        // Find the supported page size that matches, in theory default should be one of them
-        foreach (const QPageSize &ps, m_pageSizes) {
-            if (ps.windowsId() == pDevMode->dmPaperSize) {
-                pageSize = ps;
-                break;
+    if (LPDEVMODE pDevMode = getDevmode(m_hPrinter, m_id)) {
+        // Get the default paper size
+        if (pDevMode->dmFields & DM_PAPERSIZE) {
+            // Find the supported page size that matches, in theory default should be one of them
+            foreach (const QPageSize &ps, m_pageSizes) {
+                if (ps.windowsId() == pDevMode->dmPaperSize) {
+                    pageSize = ps;
+                    break;
+                }
             }
         }
+        // Clean-up
+        free(pDevMode);
     }
 
-    // Clean-up
-    free(pDevMode);
     return pageSize;
 }
 
@@ -226,20 +238,14 @@ QMarginsF QWindowsPrintDevice::printableMargins(const QPageSize &pageSize,
     QScopedArrayPointer<BYTE> buffer(new BYTE[needed]);
     if (GetPrinter(m_hPrinter, 2, buffer.data(), needed, &needed)) {
         PPRINTER_INFO_2 info = reinterpret_cast<PPRINTER_INFO_2>(buffer.data());
-        DEVMODE *devMode = info->pDevMode;
+        LPDEVMODE devMode = info->pDevMode;
         bool separateDevMode = false;
         if (!devMode) {
             // GetPrinter() didn't include the DEVMODE. Get it a different way.
-            LONG result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(),
-                                             NULL, NULL, 0);
-            devMode = (DEVMODE *)malloc(result);
-            separateDevMode = true;
-            result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(),
-                                        devMode, NULL, DM_OUT_BUFFER);
-            if (result != IDOK) {
-                free(devMode);
+            devMode = getDevmode(m_hPrinter, m_id);
+            if (!devMode)
                 return margins;
-            }
+            separateDevMode = true;
         }
 
         HDC pDC = CreateDC(NULL, (LPWSTR)m_id.utf16(), NULL, devMode);
@@ -291,23 +297,17 @@ int QWindowsPrintDevice::defaultResolution() const
 {
     int resolution = 72;  // TODO Set a sensible default?
 
-    // Allocate the required DEVMODE buffer
-    DWORD dmSize = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), NULL, NULL, 0);
-    LPDEVMODE pDevMode = (LPDEVMODE)malloc(dmSize);
-
-     // Get the default DevMode
-    DWORD result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), pDevMode, NULL, DM_OUT_BUFFER);
-
-    // Get the default resolution
-    if (result == IDOK && pDevMode->dmFields & DM_YRESOLUTION) {
-        if (pDevMode->dmPrintQuality > 0)
-            resolution = pDevMode->dmPrintQuality;
-        else
-            resolution = pDevMode->dmYResolution;
+    if (LPDEVMODE pDevMode = getDevmode(m_hPrinter, m_id)) {
+        // Get the default resolution
+        if (pDevMode->dmFields & DM_YRESOLUTION) {
+            if (pDevMode->dmPrintQuality > 0)
+                resolution = pDevMode->dmPrintQuality;
+            else
+                resolution = pDevMode->dmYResolution;
+        }
+        // Clean-up
+        free(pDevMode);
     }
-
-    // Clean-up
-    free(pDevMode);
     return resolution;
 }
 
@@ -340,26 +340,20 @@ QPrint::InputSlot QWindowsPrintDevice::defaultInputSlot() const
 {
     QPrint::InputSlot inputSlot = QPlatformPrintDevice::defaultInputSlot();;
 
-    // Allocate the required DEVMODE buffer
-    DWORD dmSize = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), NULL, NULL, 0);
-    LPDEVMODE pDevMode = (LPDEVMODE)malloc(dmSize);
-
-     // Get the default DevMode
-    DWORD result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), pDevMode, NULL, DM_OUT_BUFFER);
-
-    // Get the default input slot
-    if (result == IDOK && pDevMode->dmFields & DM_DEFAULTSOURCE) {
-        QPrint::InputSlot tempSlot = paperBinToInputSlot(pDevMode->dmDefaultSource, QString());
-        foreach (const QPrint::InputSlot &slot, supportedInputSlots()) {
-            if (slot.key == tempSlot.key) {
-                inputSlot = slot;
-                break;
+    if (LPDEVMODE pDevMode = getDevmode(m_hPrinter, m_id)) {
+        // Get the default input slot
+        if (pDevMode->dmFields & DM_DEFAULTSOURCE) {
+            QPrint::InputSlot tempSlot = paperBinToInputSlot(pDevMode->dmDefaultSource, QString());
+            foreach (const QPrint::InputSlot &slot, supportedInputSlots()) {
+                if (slot.key == tempSlot.key) {
+                    inputSlot = slot;
+                    break;
+                }
             }
         }
+        // Clean-up
+        free(pDevMode);
     }
-
-    // Clean-up
-    free(pDevMode);
     return inputSlot;
 }
 
@@ -386,23 +380,17 @@ QPrint::DuplexMode QWindowsPrintDevice::defaultDuplexMode() const
 {
     QPrint::DuplexMode duplexMode = QPrint::DuplexNone;
 
-    // Allocate the required DEVMODE buffer
-    DWORD dmSize = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), NULL, NULL, 0);
-    LPDEVMODE pDevMode = (LPDEVMODE)malloc(dmSize);
-
-     // Get the default DevMode
-    DWORD result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), pDevMode, NULL, DM_OUT_BUFFER);
-
-    // Get the default duplex mode
-    if (result == IDOK && pDevMode->dmFields & DM_DUPLEX) {
-        if (pDevMode->dmDuplex == DMDUP_VERTICAL)
-            duplexMode = QPrint::DuplexLongSide;
-        else if (pDevMode->dmDuplex == DMDUP_HORIZONTAL)
-            duplexMode = QPrint::DuplexShortSide;
+    if (LPDEVMODE pDevMode = getDevmode(m_hPrinter, m_id)) {
+        // Get the default duplex mode
+        if (pDevMode->dmFields & DM_DUPLEX) {
+            if (pDevMode->dmDuplex == DMDUP_VERTICAL)
+                duplexMode = QPrint::DuplexLongSide;
+            else if (pDevMode->dmDuplex == DMDUP_HORIZONTAL)
+                duplexMode = QPrint::DuplexShortSide;
+        }
+        // Clean-up
+        free(pDevMode);
     }
-
-    // Clean-up
-    free(pDevMode);
     return duplexMode;
 }
 
@@ -424,21 +412,13 @@ QPrint::ColorMode QWindowsPrintDevice::defaultColorMode() const
 
     QPrint::ColorMode colorMode = QPrint::GrayScale;
 
-    // Allocate the required DEVMODE buffer
-    DWORD dmSize = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), NULL, NULL, 0);
-    LPDEVMODE pDevMode = (LPDEVMODE)malloc(dmSize);
-
-     // Get the default DevMode
-    DWORD result = DocumentProperties(NULL, m_hPrinter, (LPWSTR)m_id.utf16(), pDevMode, NULL, DM_OUT_BUFFER);
-
-    // Get the default color mode
-    if (result == IDOK && pDevMode->dmFields & DM_COLOR) {
-        if (pDevMode->dmColor == DMCOLOR_COLOR)
+    if (LPDEVMODE pDevMode = getDevmode(m_hPrinter, m_id)) {
+        // Get the default color mode
+        if (pDevMode->dmFields & DM_COLOR && pDevMode->dmColor == DMCOLOR_COLOR)
             colorMode = QPrint::Color;
+        // Clean-up
+        free(pDevMode);
     }
-
-    // Clean-up
-    free(pDevMode);
     return colorMode;
 }