2 files changed, 45 insertions, 20 deletions

diff --git a/src/gui/opengl/qopenglprogrambinarycache.cpp b/src/gui/opengl/qopenglprogrambinarycache.cpp
index 631c3d151b..8b0075bf26 100644
--- a/src/gui/opengl/qopenglprogrambinarycache.cpp
+++ b/src/gui/opengl/qopenglprogrambinarycache.cpp
@@ -119,20 +119,24 @@ QOpenGLProgramBinaryCache::QOpenGLProgramBinaryCache()
 {
     const QString subPath = QLatin1String("/qtshadercache-") + QSysInfo::buildAbi() + QLatin1Char('/');
     const QString sharedCachePath = QStandardPaths::writableLocation(QStandardPaths::GenericCacheLocation);
+    m_globalCacheDir = sharedCachePath + subPath;
+    m_localCacheDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + subPath;
+
     if (!sharedCachePath.isEmpty()) {
-        m_cacheDir = sharedCachePath + subPath;
-        m_cacheWritable = qt_ensureWritableDir(m_cacheDir);
+        m_currentCacheDir = m_globalCacheDir;
+        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
     }
     if (!m_cacheWritable) {
-        m_cacheDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + subPath;
-        m_cacheWritable = qt_ensureWritableDir(m_cacheDir);
+        m_currentCacheDir = m_localCacheDir;
+        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
     }
-    qCDebug(lcOpenGLProgramDiskCache, "Cache location '%s' writable = %d", qPrintable(m_cacheDir), m_cacheWritable);
+
+    qCDebug(lcOpenGLProgramDiskCache, "Cache location '%s' writable = %d", qPrintable(m_currentCacheDir), m_cacheWritable);
 }
 
 QString QOpenGLProgramBinaryCache::cacheFileName(const QByteArray &cacheKey) const
 {
-    return m_cacheDir + QString::fromUtf8(cacheKey);
+    return m_currentCacheDir + QString::fromUtf8(cacheKey);
 }
 
 #define BASE_HEADER_SIZE (int(4 * sizeof(quint32)))
@@ -361,6 +365,25 @@ static inline void writeStr(uchar **p, const QByteArray &str)
     *p += str.size();
 }
 
+static inline bool writeFile(const QString &filename, const QByteArray &data)
+{
+#if QT_CONFIG(temporaryfile)
+    QSaveFile f(filename);
+    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        f.write(data);
+        if (f.commit())
+            return true;
+    }
+#else
+    QFile f(filename);
+    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        if (f.write(data) == data.length())
+            return true;
+    }
+#endif
+    return false;
+}
+
 void QOpenGLProgramBinaryCache::save(const QByteArray &cacheKey, uint programId)
 {
     if (!m_cacheWritable)
@@ -427,20 +450,20 @@ void QOpenGLProgramBinaryCache::save(const QByteArray &cacheKey, uint programId)
 
     writeUInt(&blobFormatPtr, blobFormat);
 
-#if QT_CONFIG(temporaryfile)
-    QSaveFile f(cacheFileName(cacheKey));
-    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
-        f.write(blob);
-        if (!f.commit())
-#else
-    QFile f(cacheFileName(cacheKey));
-    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
-        if (f.write(blob) < blob.length())
-#endif
-            qCDebug(lcOpenGLProgramDiskCache, "Failed to write %s to shader cache", qPrintable(f.fileName()));
-    } else {
-        qCDebug(lcOpenGLProgramDiskCache, "Failed to create %s in shader cache", qPrintable(f.fileName()));
+    QString filename = cacheFileName(cacheKey);
+    bool ok = writeFile(filename, blob);
+    if (!ok && m_currentCacheDir == m_globalCacheDir) {
+        m_currentCacheDir = m_localCacheDir;
+        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
+        qCDebug(lcOpenGLProgramDiskCache, "Cache location changed to '%s' writable = %d",
+                qPrintable(m_currentCacheDir), m_cacheWritable);
+        if (m_cacheWritable) {
+            filename = cacheFileName(cacheKey);
+            ok = writeFile(filename, blob);
+        }
     }
+    if (!ok)
+        qCDebug(lcOpenGLProgramDiskCache, "Failed to write %s to shader cache", qPrintable(filename));
 }
 
 #if QT_CONFIG(opengles2)
diff --git a/src/gui/opengl/qopenglprogrambinarycache_p.h b/src/gui/opengl/qopenglprogrambinarycache_p.h
index d8fdf1d8c5..6871955dd3 100644
--- a/src/gui/opengl/qopenglprogrambinarycache_p.h
+++ b/src/gui/opengl/qopenglprogrambinarycache_p.h
@@ -92,7 +92,9 @@ private:
     bool verifyHeader(const QByteArray &buf) const;
     bool setProgramBinary(uint programId, uint blobFormat, const void *p, uint blobSize);
 
-    QString m_cacheDir;
+    QString m_globalCacheDir;
+    QString m_localCacheDir;
+    QString m_currentCacheDir;
     bool m_cacheWritable;
     struct MemCacheEntry {
         MemCacheEntry(const void *p, int size, uint format)