Separate header verification and mmap handling of CompiledData::Unit

...into a separate class. This will make it easier to specialize the
handling for Posix and Windows platforms.

Change-Id: I995538fa8239eac8586c96812086e50b4c19257f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

5 files changed, 207 insertions, 48 deletions

diff --git a/src/qml/compiler/compiler.pri b/src/qml/compiler/compiler.pri
index ad73c26b15..02288a8ad7 100644
--- a/src/qml/compiler/compiler.pri
+++ b/src/qml/compiler/compiler.pri
@@ -28,7 +28,8 @@ HEADERS += \
     $$PWD/qv4isel_moth_p.h \
     $$PWD/qv4instr_moth_p.h \
     $$PWD/qqmlpropertycachecreator_p.h \
-    $$PWD/qqmlpropertyvalidator_p.h
+    $$PWD/qqmlpropertyvalidator_p.h \
+    $$PWD/qv4compilationunitmapper_p.h
 
 
 SOURCES += \
@@ -36,6 +37,7 @@ SOURCES += \
     $$PWD/qv4instr_moth.cpp \
     $$PWD/qv4isel_moth.cpp \
     $$PWD/qqmlpropertycachecreator.cpp \
-    $$PWD/qqmlpropertyvalidator.cpp
+    $$PWD/qqmlpropertyvalidator.cpp \
+    $$PWD/qv4compilationunitmapper.cpp
 
 }
diff --git a/src/qml/compiler/qv4compilationunitmapper.cpp b/src/qml/compiler/qv4compilationunitmapper.cpp
new file mode 100644
index 0000000000..1d8be036c9
--- /dev/null
+++ b/src/qml/compiler/qv4compilationunitmapper.cpp
@@ -0,0 +1,114 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qv4compilationunitmapper_p.h"
+
+#include "qv4compileddata_p.h"
+#include <QFileInfo>
+#include <QDateTime>
+
+QT_BEGIN_NAMESPACE
+
+using namespace QV4;
+
+CompilationUnitMapper::CompilationUnitMapper()
+    : dataPtr(nullptr)
+{
+
+}
+
+CompiledData::Unit *CompilationUnitMapper::open(const QString &sourcePath, QString *errorString)
+{
+    close();
+
+    f.setFileName(sourcePath + QLatin1Char('c'));
+    if (!f.open(QIODevice::ReadOnly)) {
+        *errorString = f.errorString();
+        return nullptr;
+    }
+
+    CompiledData::Unit header;
+    qint64 bytesRead = f.read(reinterpret_cast<char *>(&header), sizeof(header));
+
+    if (bytesRead != sizeof(header)) {
+        *errorString = QStringLiteral("File too small for the header fields");
+        return nullptr;
+    }
+
+    if (strncmp(header.magic, CompiledData::magic_str, sizeof(header.magic))) {
+        *errorString = QStringLiteral("Magic bytes in the header do not match");
+        return nullptr;
+    }
+
+    if (header.version != quint32(QV4_DATA_STRUCTURE_VERSION)) {
+        *errorString = QString::fromUtf8("V4 data structure version mismatch. Found %1 expected %2").arg(header.version, 0, 16).arg(QV4_DATA_STRUCTURE_VERSION, 0, 16);
+        return nullptr;
+    }
+
+    if (header.qtVersion != quint32(QT_VERSION)) {
+        *errorString = QString::fromUtf8("Qt version mismatch. Found %1 expected %2").arg(header.qtVersion, 0, 16).arg(QT_VERSION, 0, 16);
+        return nullptr;
+    }
+
+    {
+        QFileInfo sourceCode(sourcePath);
+        if (sourceCode.exists() && sourceCode.lastModified().toMSecsSinceEpoch() != header.sourceTimeStamp) {
+            *errorString = QStringLiteral("QML source file has a different time stamp than cached file.");
+            return nullptr;
+        }
+    }
+
+    // Data structure and qt version matched, so now we can access the rest of the file safely.
+
+    dataPtr = f.map(/*offset*/0, f.size());
+    if (!dataPtr) {
+        *errorString = f.errorString();
+        return nullptr;
+    }
+
+    return reinterpret_cast<CompiledData::Unit*>(dataPtr);
+}
+
+void CompilationUnitMapper::close()
+{
+    f.close();
+    dataPtr = nullptr;
+}
+
+QT_END_NAMESPACE
diff --git a/src/qml/compiler/qv4compilationunitmapper_p.h b/src/qml/compiler/qv4compilationunitmapper_p.h
new file mode 100644
index 0000000000..06ca3d0e02
--- /dev/null
+++ b/src/qml/compiler/qv4compilationunitmapper_p.h
@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QV4COMPILATIONUNITMAPPER_H
+#define QV4COMPILATIONUNITMAPPER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qv4global_p.h>
+#include <QFile>
+
+QT_BEGIN_NAMESPACE
+
+namespace QV4 {
+
+namespace CompiledData {
+struct Unit;
+}
+
+class CompilationUnitMapper
+{
+public:
+    CompilationUnitMapper();
+
+    CompiledData::Unit *open(const QString &sourcePath, QString *errorString);
+    void close();
+
+private:
+    QFile f;
+    uchar *dataPtr;
+};
+
+}
+
+QT_END_NAMESPACE
+
+#endif // QV4COMPILATIONUNITMAPPER_H
diff --git a/src/qml/compiler/qv4compileddata.cpp b/src/qml/compiler/qv4compileddata.cpp
index 98eb7188cc..cc1f8ae261 100644
--- a/src/qml/compiler/qv4compileddata.cpp
+++ b/src/qml/compiler/qv4compileddata.cpp
@@ -49,6 +49,7 @@
 #include <private/qqmlpropertycache_p.h>
 #include <private/qqmltypeloader_p.h>
 #include <private/qqmlengine_p.h>
+#include "qv4compilationunitmapper_p.h"
 #include <QQmlPropertyMap>
 #include <QDateTime>
 #include <QSaveFile>
@@ -376,56 +377,15 @@ bool CompilationUnit::loadFromDisk(const QUrl &url, EvalISelFactory *iselFactory
     }
 
     const QString sourcePath = url.toLocalFile();
-    QScopedPointer<QFile> cacheFile(new QFile(sourcePath + QLatin1Char('c')));
+    QScopedPointer<CompilationUnitMapper> cacheFile(new CompilationUnitMapper());
 
-    if (!cacheFile->open(QIODevice::ReadOnly)) {
-        *errorString = cacheFile->errorString();
-        return false;
-    }
-
-    {
-        CompiledData::Unit header;
-        qint64 bytesRead = cacheFile->read(reinterpret_cast<char *>(&header), sizeof(header));
-
-        if (bytesRead != sizeof(header)) {
-            *errorString = QStringLiteral("File too small for the header fields");
-            return false;
-        }
-
-        if (strncmp(header.magic, CompiledData::magic_str, sizeof(header.magic))) {
-            *errorString = QStringLiteral("Magic bytes in the header do not match");
-            return false;
-        }
-
-        if (header.version != quint32(QV4_DATA_STRUCTURE_VERSION)) {
-            *errorString = QString::fromUtf8("V4 data structure version mismatch. Found %1 expected %2").arg(header.version, 0, 16).arg(QV4_DATA_STRUCTURE_VERSION, 0, 16);
-            return false;
-        }
-
-        if (header.qtVersion != quint32(QT_VERSION)) {
-            *errorString = QString::fromUtf8("Qt version mismatch. Found %1 expected %2").arg(header.qtVersion, 0, 16).arg(QT_VERSION, 0, 16);
-            return false;
-        }
-
-        {
-            QFileInfo sourceCode(sourcePath);
-            if (sourceCode.exists() && sourceCode.lastModified().toMSecsSinceEpoch() != header.sourceTimeStamp) {
-                *errorString = QStringLiteral("QML source file has a different time stamp than cached file.");
-                return false;
-            }
-        }
-
-    }
-    // Data structure and qt version matched, so now we can access the rest of the file safely.
-
-    uchar *cacheData = cacheFile->map(/*offset*/0, cacheFile->size());
-    if (!cacheData) {
-        *errorString = cacheFile->errorString();
+    CompiledData::Unit *mappedUnit = cacheFile->open(sourcePath, errorString);
+    if (!mappedUnit) {
         return false;
     }
 
     const Unit * const oldDataPtr = (data && !(data->flags & QV4::CompiledData::Unit::StaticData)) ? data : nullptr;
-    QScopedValueRollback<const Unit *> dataPtrChange(data, reinterpret_cast<const Unit *>(cacheData));
+    QScopedValueRollback<const Unit *> dataPtrChange(data, mappedUnit);
 
     {
         const QString foundArchitecture = stringAt(data->architectureIndex);
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 0903654e51..a6ca1594a4 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -92,6 +92,7 @@ struct Function;
 
 struct Function;
 class EvalISelFactory;
+class CompilationUnitMapper;
 
 namespace CompiledData {
 
@@ -874,7 +875,7 @@ struct Q_QML_PRIVATE_EXPORT CompilationUnit : public QQmlRefCount
     int listMetaTypeId;
     bool isRegisteredWithEngine;
 
-    QScopedPointer<QIODevice> backingFile;
+    QScopedPointer<CompilationUnitMapper> backingFile;
 
     // --- interface for QQmlPropertyCacheCreator
     typedef Object CompiledObject;