From 5aedb778707f2707d66eb848276e8c2f0b4d447c Mon Sep 17 00:00:00 2001
From: ABBAPOH <ABBAPOH@nextmail.ru>
Date: Fri, 13 Dec 2013 19:21:27 +0400
Subject: Do not try to rescan device in case of an error in DDS plugin.

Change-Id: I64b49294476fc3bbf77620d839b88b0ecea68e23
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Alex Char <prevedtest@gmail.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
---
 src/plugins/imageformats/dds/qddshandler.cpp | 18 ++++++++++--------
 src/plugins/imageformats/dds/qddshandler.h   | 10 ++++++++--
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/plugins/imageformats/dds/qddshandler.cpp b/src/plugins/imageformats/dds/qddshandler.cpp
index 2b132b5..428659f 100644
--- a/src/plugins/imageformats/dds/qddshandler.cpp
+++ b/src/plugins/imageformats/dds/qddshandler.cpp
@@ -1227,7 +1227,7 @@ static QImage readCubeMap(QDataStream &s, const DDSHeader &dds, const int fmt)
 
 QDDSHandler::QDDSHandler() :
     m_currentImage(0),
-    m_headerCached(false)
+    m_scanState(ScanNotScanned)
 {
 }
 
@@ -1247,7 +1247,7 @@ bool QDDSHandler::canRead() const
 
 bool QDDSHandler::read(QImage *outImage)
 {
-    if (!ensureHeaderCached() || device()->isSequential())
+    if (!ensureScanned() || device()->isSequential())
         return false;
 
     qint64 pos = headerSize + mipmapOffset(m_header, m_format, m_currentImage);
@@ -1321,7 +1321,7 @@ bool QDDSHandler::write(const QImage &outImage)
 
 QVariant QDDSHandler::option(QImageIOHandler::ImageOption option) const
 {
-    if (!supportsOption(option) || !ensureHeaderCached())
+    if (!supportsOption(option) || !ensureScanned())
         return QVariant();
 
     switch (option) {
@@ -1341,7 +1341,7 @@ bool QDDSHandler::supportsOption(QImageIOHandler::ImageOption option) const
 
 int QDDSHandler::imageCount() const
 {
-    if (!ensureHeaderCached())
+    if (!ensureScanned())
         return 0;
 
     return qMax<quint32>(1, m_header.mipMapCount);
@@ -1369,10 +1369,12 @@ bool QDDSHandler::canRead(QIODevice *device)
     return device->peek(4) == QByteArrayLiteral("DDS ");
 }
 
-bool QDDSHandler::ensureHeaderCached() const
+bool QDDSHandler::ensureScanned() const
 {
-    if (m_headerCached)
-        return true;
+    if (m_scanState != ScanNotScanned)
+        return m_scanState == ScanSuccess;
+
+    m_scanState = ScanError;
 
     if (device()->isSequential()) {
         qWarning() << "Sequential devices are not supported";
@@ -1399,7 +1401,7 @@ bool QDDSHandler::ensureHeaderCached() const
 
     that->m_format = getFormat(m_header);
 
-    m_headerCached = true;
+    m_scanState = ScanSuccess;
     return true;
 }
 
diff --git a/src/plugins/imageformats/dds/qddshandler.h b/src/plugins/imageformats/dds/qddshandler.h
index 542bd35..582a013 100644
--- a/src/plugins/imageformats/dds/qddshandler.h
+++ b/src/plugins/imageformats/dds/qddshandler.h
@@ -70,15 +70,21 @@ public:
     static bool canRead(QIODevice *device);
 
 private:
-    bool ensureHeaderCached() const;
+    bool ensureScanned() const;
     bool verifyHeader(const DDSHeader &dds) const;
 
 private:
+    enum ScanState {
+        ScanError = -1,
+        ScanNotScanned = 0,
+        ScanSuccess = 1,
+    };
+
     DDSHeader m_header;
     int m_format;
     DDSHeaderDX10 m_header10;
     int m_currentImage;
-    mutable bool m_headerCached;
+    mutable ScanState m_scanState;
 };
 
 QT_END_NAMESPACE
-- 
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