implement simple VFS to support caching during project parsing

sync up with qt creator.
this counts as a bugfix, because it makes write_file() and cache() do
something remotely useful.

Change-Id: I833253f81c3159056fab2ff888f293b36cc2ef56
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
(cherry picked from qtbase/b215176da34661969015e4950815fe8297885163)
(cherry picked from qtcreator/66802ef8bf7989dc025e34bf91d93576189c483c)

12 files changed, 331 insertions, 81 deletions

diff --git a/src/linguist/lrelease/main.cpp b/src/linguist/lrelease/main.cpp
index 2d6b60a4a..8116616a9 100644
--- a/src/linguist/lrelease/main.cpp
+++ b/src/linguist/lrelease/main.cpp
@@ -41,6 +41,7 @@
 
 #include "translator.h"
 
+#include <qmakevfs.h>
 #include <qmakeparser.h>
 #include <profileevaluator.h>
 
@@ -318,8 +319,9 @@ int main(int argc, char **argv)
                 option.qmake_abslocation = app.applicationDirPath() + QLatin1String("/qmake");
 #endif
             option.initProperties();
-            QMakeParser parser(0, &evalHandler);
-            ProFileEvaluator visitor(&option, &parser, &evalHandler);
+            QMakeVfs vfs;
+            QMakeParser parser(0, &vfs, &evalHandler);
+            ProFileEvaluator visitor(&option, &parser, &vfs, &evalHandler);
             visitor.setCumulative(true);
             visitor.setOutputDir(QDir::currentPath());
 
diff --git a/src/linguist/lupdate/main.cpp b/src/linguist/lupdate/main.cpp
index ec2be5747..bf98c8d85 100644
--- a/src/linguist/lupdate/main.cpp
+++ b/src/linguist/lupdate/main.cpp
@@ -42,6 +42,7 @@
 #include "lupdate.h"
 
 #include <translator.h>
+#include <qmakevfs.h>
 #include <qmakeparser.h>
 #include <profileevaluator.h>
 
@@ -374,14 +375,15 @@ static void processSources(Translator &fetchedTor,
 }
 
 static void processProjects(bool topLevel, bool nestComplain, const QStringList &proFiles,
-        const QHash<QString, QString> &outDirMap, ProFileGlobals *option, QMakeParser *parser,
+        const QHash<QString, QString> &outDirMap,
+        ProFileGlobals *option, QMakeVfs *vfs, QMakeParser *parser,
         UpdateOptions options,
         const QString &targetLanguage, const QString &sourceLanguage,
         Translator *parentTor, bool *fail);
 
 static void processProject(
         bool nestComplain, const QString &proFile,
-        ProFileGlobals *option, QMakeParser *parser, ProFileEvaluator &visitor,
+        ProFileGlobals *option, QMakeVfs *vfs, QMakeParser *parser, ProFileEvaluator &visitor,
         UpdateOptions options,
         const QString &targetLanguage, const QString &sourceLanguage,
         Translator *fetchedTor, bool *fail)
@@ -421,7 +423,7 @@ static void processProject(
                 subProFiles << subPro;
         }
         processProjects(false, nestComplain, subProFiles, QHash<QString, QString>(),
-                        option, parser, options,
+                        option, vfs, parser, options,
                         targetLanguage, sourceLanguage, fetchedTor, fail);
     } else {
         ConversionData cd;
@@ -447,7 +449,8 @@ static void processProject(
 }
 
 static void processProjects(bool topLevel, bool nestComplain, const QStringList &proFiles,
-        const QHash<QString, QString> &outDirMap, ProFileGlobals *option, QMakeParser *parser,
+        const QHash<QString, QString> &outDirMap,
+        ProFileGlobals *option, QMakeVfs *vfs, QMakeParser *parser,
         UpdateOptions options,
         const QString &targetLanguage, const QString &sourceLanguage,
         Translator *parentTor, bool *fail)
@@ -457,7 +460,7 @@ static void processProjects(bool topLevel, bool nestComplain, const QStringList
         if (!outDirMap.isEmpty())
             option->setDirectories(QFileInfo(proFile).path(), outDirMap[proFile]);
 
-        ProFileEvaluator visitor(option, parser, &evalHandler);
+        ProFileEvaluator visitor(option, parser, vfs, &evalHandler);
         visitor.setCumulative(true);
         visitor.setOutputDir(option->shadowedPath(proFile));
         ProFile *pro;
@@ -499,7 +502,7 @@ static void processProjects(bool topLevel, bool nestComplain, const QStringList
                 continue;
             }
             Translator tor;
-            processProject(false, proFile, option, parser, visitor, options,
+            processProject(false, proFile, option, vfs, parser, visitor, options,
                            targetLanguage, sourceLanguage, &tor, fail);
             updateTsFiles(tor, tsFiles, QStringList(),
                           sourceLanguage, targetLanguage, options, fail);
@@ -512,10 +515,10 @@ static void processProjects(bool topLevel, bool nestComplain, const QStringList
                 printErr(LU::tr("lupdate warning: no TS files specified. Only diagnostics "
                                 "will be produced for '%1'.\n").arg(proFile));
             Translator tor;
-            processProject(nestComplain, proFile, option, parser, visitor, options,
+            processProject(nestComplain, proFile, option, vfs, parser, visitor, options,
                            targetLanguage, sourceLanguage, &tor, fail);
         } else {
-            processProject(nestComplain, proFile, option, parser, visitor, options,
+            processProject(nestComplain, proFile, option, vfs, parser, visitor, options,
                            targetLanguage, sourceLanguage, parentTor, fail);
         }
         pro->deref();
@@ -854,16 +857,17 @@ int main(int argc, char **argv)
         option.initProperties();
         option.setCommandLineArguments(QDir::currentPath(),
                                        QStringList() << QLatin1String("CONFIG+=lupdate_run"));
-        QMakeParser parser(0, &evalHandler);
+        QMakeVfs vfs;
+        QMakeParser parser(0, &vfs, &evalHandler);
 
         if (!tsFileNames.isEmpty()) {
             Translator fetchedTor;
-            processProjects(true, true, proFiles, outDirMap, &option, &parser, options,
+            processProjects(true, true, proFiles, outDirMap, &option, &vfs, &parser, options,
                             targetLanguage, sourceLanguage, &fetchedTor, &fail);
             updateTsFiles(fetchedTor, tsFileNames, alienFiles,
                           sourceLanguage, targetLanguage, options, &fail);
         } else {
-            processProjects(true, false, proFiles, outDirMap, &option, &parser, options,
+            processProjects(true, false, proFiles, outDirMap, &option, &vfs, &parser, options,
                             targetLanguage, sourceLanguage, 0, &fail);
         }
     }
diff --git a/src/linguist/shared/profileevaluator.cpp b/src/linguist/shared/profileevaluator.cpp
index f22b3f48b..58ad162d9 100644
--- a/src/linguist/shared/profileevaluator.cpp
+++ b/src/linguist/shared/profileevaluator.cpp
@@ -55,9 +55,9 @@ void ProFileEvaluator::initialize()
     QMakeEvaluator::initStatics();
 }
 
-ProFileEvaluator::ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser,
+ProFileEvaluator::ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
                                    QMakeHandler *handler)
-  : d(new QMakeEvaluator(option, parser, handler))
+  : d(new QMakeEvaluator(option, parser, vfs, handler))
 {
 }
 
diff --git a/src/linguist/shared/profileevaluator.h b/src/linguist/shared/profileevaluator.h
index 6046b1bae..8a7c5c84f 100644
--- a/src/linguist/shared/profileevaluator.h
+++ b/src/linguist/shared/profileevaluator.h
@@ -52,6 +52,7 @@
 
 QT_BEGIN_NAMESPACE
 
+class QMakeVfs;
 class QMakeParser;
 class QMakeEvaluator;
 class QMakeHandler;
@@ -77,7 +78,8 @@ public:
     // Call this from a concurrency-free context
     static void initialize();
 
-    ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeHandler *handler);
+    ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
+                     QMakeHandler *handler);
     ~ProFileEvaluator();
 
     ProFileEvaluator::TemplateType templateType() const;
diff --git a/src/linguist/shared/proparser.pri b/src/linguist/shared/proparser.pri
index 69e09c8d7..124227bc4 100644
--- a/src/linguist/shared/proparser.pri
+++ b/src/linguist/shared/proparser.pri
@@ -6,6 +6,7 @@ DEFINES += PROEVALUATOR_CUMULATIVE PROEVALUATOR_INIT_PROPS
 HEADERS += \
     $$PWD/qmake_global.h \
     $$PWD/ioutils.h \
+    $$PWD/qmakevfs.h \
     $$PWD/proitems.h \
     $$PWD/qmakeglobals.h \
     $$PWD/qmakeparser.h \
@@ -15,6 +16,7 @@ HEADERS += \
 
 SOURCES += \
     $$PWD/ioutils.cpp \
+    $$PWD/qmakevfs.cpp \
     $$PWD/proitems.cpp \
     $$PWD/qmakeglobals.cpp \
     $$PWD/qmakeparser.cpp \
diff --git a/src/linguist/shared/qmakebuiltins.cpp b/src/linguist/shared/qmakebuiltins.cpp
index 2ccce2653..b4694cfb9 100644
--- a/src/linguist/shared/qmakebuiltins.cpp
+++ b/src/linguist/shared/qmakebuiltins.cpp
@@ -44,6 +44,7 @@
 #include "qmakeevaluator_p.h"
 #include "qmakeglobals.h"
 #include "qmakeparser.h"
+#include "qmakevfs.h"
 #include "ioutils.h"
 
 #include <qbytearray.h>
@@ -281,41 +282,12 @@ quoteValue(const ProString &val)
     return ret;
 }
 
-static bool
-doWriteFile(const QString &name, QIODevice::OpenMode mode, const QString &contents, QString *errStr)
-{
-    QByteArray bytes = contents.toLocal8Bit();
-    QFile cfile(name);
-    if (!(mode & QIODevice::Append) && cfile.open(QIODevice::ReadOnly | QIODevice::Text)) {
-        if (cfile.readAll() == bytes)
-            return true;
-        cfile.close();
-    }
-    if (!cfile.open(mode | QIODevice::WriteOnly | QIODevice::Text)) {
-        *errStr = cfile.errorString();
-        return false;
-    }
-    cfile.write(bytes);
-    cfile.close();
-    if (cfile.error() != QFile::NoError) {
-        *errStr = cfile.errorString();
-        return false;
-    }
-    return true;
-}
-
 QMakeEvaluator::VisitReturn
 QMakeEvaluator::writeFile(const QString &ctx, const QString &fn, QIODevice::OpenMode mode,
                           const QString &contents)
 {
-    QFileInfo qfi(fn);
-    if (!QDir::current().mkpath(qfi.path())) {
-        evalError(fL1S("Cannot create %1directory %2.")
-                  .arg(ctx, QDir::toNativeSeparators(qfi.path())));
-        return ReturnFalse;
-    }
     QString errStr;
-    if (!doWriteFile(fn, mode, contents, &errStr)) {
+    if (!m_vfs->writeFile(fn, mode, contents, &errStr)) {
         evalError(fL1S("Cannot write %1file %2: %3.")
                   .arg(ctx, QDir::toNativeSeparators(fn), errStr));
         return ReturnFalse;
@@ -1427,6 +1399,9 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
         }
         const QString &file = resolvePath(m_option->expandEnvVars(args.at(0).toQString(m_tmp1)));
 
+        // Don't use VFS here:
+        // - it supports neither listing nor even directories
+        // - it's unlikely that somebody would test for files they created themselves
         if (IoUtils::exists(file))
             return ReturnTrue;
         int slsh = file.lastIndexOf(QLatin1Char('/'));
@@ -1458,7 +1433,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             evalError(fL1S("write_file(name, [content var, [append]]) requires one to three arguments."));
             return ReturnFalse;
         }
-#ifdef PROEVALUATOR_FULL
         QIODevice::OpenMode mode = QIODevice::Truncate;
         QString contents;
         if (args.count() >= 2) {
@@ -1470,9 +1444,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
                     mode = QIODevice::Append;
         }
         return writeFile(QString(), resolvePath(args.at(0).toQString(m_tmp1)), mode, contents);
-#else
-        return ReturnTrue;
-#endif
     }
     case T_TOUCH: {
         if (args.count() != 2) {
@@ -1524,7 +1495,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             evalError(fL1S("cache(var, [set|add|sub] [transient] [super], [srcvar]) requires one to three arguments."));
             return ReturnFalse;
         }
-#ifdef PROEVALUATOR_FULL
         bool persist = true;
         bool super = false;
         enum { CacheSet, CacheAdd, CacheSub } mode = CacheSet;
@@ -1650,9 +1620,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             fn = m_cachefile;
         }
         return writeFile(fL1S("cache "), fn, QIODevice::Append, varstr);
-#else
-        return ReturnTrue;
-#endif
     }
     default:
         evalError(fL1S("Function '%1' is not implemented.").arg(function.toQString(m_tmp1)));
diff --git a/src/linguist/shared/qmakeevaluator.cpp b/src/linguist/shared/qmakeevaluator.cpp
index 9c7bf4546..4bf1ea25a 100644
--- a/src/linguist/shared/qmakeevaluator.cpp
+++ b/src/linguist/shared/qmakeevaluator.cpp
@@ -44,6 +44,7 @@
 
 #include "qmakeglobals.h"
 #include "qmakeparser.h"
+#include "qmakevfs.h"
 #include "ioutils.h"
 
 #include <qbytearray.h>
@@ -174,13 +175,13 @@ const ProKey &QMakeEvaluator::map(const ProKey &var)
 }
 
 
-QMakeEvaluator::QMakeEvaluator(QMakeGlobals *option,
-                               QMakeParser *parser, QMakeHandler *handler)
+QMakeEvaluator::QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
+                               QMakeHandler *handler)
   :
 #ifdef PROEVALUATOR_DEBUG
     m_debugLevel(option->debugLevel),
 #endif
-    m_option(option), m_parser(parser), m_handler(handler)
+    m_option(option), m_parser(parser), m_handler(handler), m_vfs(vfs)
 {
     // So that single-threaded apps don't have to call initialize() for now.
     initStatics();
@@ -1066,7 +1067,7 @@ bool QMakeEvaluator::prepareProject(const QString &inDir)
             superdir = m_outputDir;
             forever {
                 QString superfile = superdir + QLatin1String("/.qmake.super");
-                if (IoUtils::exists(superfile)) {
+                if (m_vfs->exists(superfile)) {
                     m_superfile = QDir::cleanPath(superfile);
                     break;
                 }
@@ -1081,10 +1082,10 @@ bool QMakeEvaluator::prepareProject(const QString &inDir)
             QString dir = m_outputDir;
             forever {
                 conffile = sdir + QLatin1String("/.qmake.conf");
-                if (!IoUtils::exists(conffile))
+                if (!m_vfs->exists(conffile))
                     conffile.clear();
                 cachefile = dir + QLatin1String("/.qmake.cache");
-                if (!IoUtils::exists(cachefile))
+                if (!m_vfs->exists(cachefile))
                     cachefile.clear();
                 if (!conffile.isEmpty() || !cachefile.isEmpty()) {
                     if (dir != sdir)
@@ -1175,7 +1176,7 @@ bool QMakeEvaluator::loadSpec()
                 m_hostBuild ? m_option->qmakespec : m_option->xqmakespec);
 
     {
-        QMakeEvaluator evaluator(m_option, m_parser, m_handler);
+        QMakeEvaluator evaluator(m_option, m_parser, m_vfs, m_handler);
         if (!m_superfile.isEmpty()) {
             valuesRef(ProKey("_QMAKE_SUPER_CACHE_")) << ProString(m_superfile);
             if (evaluator.evaluateFile(
@@ -1332,7 +1333,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::visitProFile(
                 locker.unlock();
 #endif
 
-                QMakeEvaluator *baseEval = new QMakeEvaluator(m_option, m_parser, m_handler);
+                QMakeEvaluator *baseEval = new QMakeEvaluator(m_option, m_parser, m_vfs, m_handler);
                 baseEnv->evaluator = baseEval;
                 baseEval->m_superfile = m_superfile;
                 baseEval->m_conffile = m_conffile;
@@ -1910,7 +1911,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateFeatureFile(
 QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateFileInto(
         const QString &fileName, ProValueMap *values, LoadFlags flags)
 {
-    QMakeEvaluator visitor(m_option, m_parser, m_handler);
+    QMakeEvaluator visitor(m_option, m_parser, m_vfs, m_handler);
     visitor.m_caller = this;
     visitor.m_outputDir = m_outputDir;
     visitor.m_featureRoots = m_featureRoots;
diff --git a/src/linguist/shared/qmakeevaluator.h b/src/linguist/shared/qmakeevaluator.h
index 21f487a3b..f4e65e396 100644
--- a/src/linguist/shared/qmakeevaluator.h
+++ b/src/linguist/shared/qmakeevaluator.h
@@ -108,7 +108,7 @@ public:
 
     static void initStatics();
     static void initFunctionStatics();
-    QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser,
+    QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
                    QMakeHandler *handler);
     ~QMakeEvaluator();
 
@@ -294,6 +294,7 @@ public:
     QMakeGlobals *m_option;
     QMakeParser *m_parser;
     QMakeHandler *m_handler;
+    QMakeVfs *m_vfs;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QMakeEvaluator::LoadFlags)
diff --git a/src/linguist/shared/qmakeparser.cpp b/src/linguist/shared/qmakeparser.cpp
index c61375be3..34e99a82a 100644
--- a/src/linguist/shared/qmakeparser.cpp
+++ b/src/linguist/shared/qmakeparser.cpp
@@ -41,6 +41,7 @@
 
 #include "qmakeparser.h"
 
+#include "qmakevfs.h"
 #include "ioutils.h"
 using namespace QMakeInternal;
 
@@ -142,9 +143,10 @@ void QMakeParser::initialize()
     statics.strLITERAL_WHITESPACE = QLatin1String("LITERAL_WHITESPACE");
 }
 
-QMakeParser::QMakeParser(ProFileCache *cache, QMakeParserHandler *handler)
+QMakeParser::QMakeParser(ProFileCache *cache, QMakeVfs *vfs, QMakeParserHandler *handler)
     : m_cache(cache)
     , m_handler(handler)
+    , m_vfs(vfs)
 {
     // So that single-threaded apps don't have to call initialize() for now.
     initialize();
@@ -230,24 +232,14 @@ void QMakeParser::discardFileFromCache(const QString &fileName)
 
 bool QMakeParser::read(ProFile *pro, ParseFlags flags)
 {
-    QFile file(pro->fileName());
-    if (!file.open(QIODevice::ReadOnly)) {
-        if (m_handler && ((flags & ParseReportMissing) || IoUtils::exists(pro->fileName())))
+    QString content;
+    QString errStr;
+    if (!m_vfs->readFile(pro->fileName(), &content, &errStr)) {
+        if (m_handler && ((flags & ParseReportMissing) || m_vfs->exists(pro->fileName())))
             m_handler->message(QMakeParserHandler::ParserIoError,
-                               fL1S("Cannot read %1: %2").arg(pro->fileName(), file.errorString()));
+                               fL1S("Cannot read %1: %2").arg(pro->fileName(), errStr));
         return false;
     }
-
-    QByteArray bcont = file.readAll();
-    if (bcont.startsWith("\xef\xbb\xbf")) {
-        // UTF-8 BOM will cause subtle errors
-        m_handler->message(QMakeParserHandler::ParserIoError,
-                           fL1S("Unexpected UTF-8 BOM in %1").arg(pro->fileName()));
-        return false;
-    }
-    QString content(QString::fromLocal8Bit(bcont));
-    bcont.clear();
-    file.close();
     return read(pro, content, 1, FullGrammar);
 }
 
diff --git a/src/linguist/shared/qmakeparser.h b/src/linguist/shared/qmakeparser.h
index e1dd09094..dd55659d8 100644
--- a/src/linguist/shared/qmakeparser.h
+++ b/src/linguist/shared/qmakeparser.h
@@ -79,6 +79,7 @@ public:
 };
 
 class ProFileCache;
+class QMakeVfs;
 
 class QMAKE_EXPORT QMakeParser
 {
@@ -93,7 +94,7 @@ public:
     };
     Q_DECLARE_FLAGS(ParseFlags, ParseFlag)
 
-    QMakeParser(ProFileCache *cache, QMakeParserHandler *handler);
+    QMakeParser(ProFileCache *cache, QMakeVfs *vfs, QMakeParserHandler *handler);
 
     enum SubGrammar { FullGrammar, TestGrammar, ValueGrammar };
     // fileName is expected to be absolute and cleanPath()ed.
@@ -182,6 +183,7 @@ private:
 
     ProFileCache *m_cache;
     QMakeParserHandler *m_handler;
+    QMakeVfs *m_vfs;
 
     // This doesn't help gcc 3.3 ...
     template<typename T> friend class QTypeInfo;
diff --git a/src/linguist/shared/qmakevfs.cpp b/src/linguist/shared/qmakevfs.cpp
new file mode 100644
index 000000000..cfa5f2974
--- /dev/null
+++ b/src/linguist/shared/qmakevfs.cpp
@@ -0,0 +1,192 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Linguist 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qmakevfs.h"
+
+#include "ioutils.h"
+using namespace QMakeInternal;
+
+#include <qdir.h>
+#include <qfile.h>
+#include <qfileinfo.h>
+
+#define fL1S(s) QString::fromLatin1(s)
+
+QT_BEGIN_NAMESPACE
+
+QMakeVfs::QMakeVfs()
+#ifndef PROEVALUATOR_FULL
+    : m_magicMissing(fL1S("missing"))
+    , m_magicExisting(fL1S("existing"))
+#endif
+{
+}
+
+bool QMakeVfs::writeFile(const QString &fn, QIODevice::OpenMode mode, const QString &contents,
+                         QString *errStr)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QString *cont = &m_files[fn];
+    if (mode & QIODevice::Append)
+        *cont += contents;
+    else
+        *cont = contents;
+    Q_UNUSED(errStr)
+    return true;
+#else
+    QFileInfo qfi(fn);
+    if (!QDir::current().mkpath(qfi.path())) {
+        *errStr = fL1S("Cannot create parent directory");
+        return false;
+    }
+    QByteArray bytes = contents.toLocal8Bit();
+    QFile cfile(fn);
+    if (!(mode & QIODevice::Append) && cfile.open(QIODevice::ReadOnly | QIODevice::Text)) {
+        if (cfile.readAll() == bytes)
+            return true;
+        cfile.close();
+    }
+    if (!cfile.open(mode | QIODevice::WriteOnly | QIODevice::Text)) {
+        *errStr = cfile.errorString();
+        return false;
+    }
+    cfile.write(bytes);
+    cfile.close();
+    if (cfile.error() != QFile::NoError) {
+        *errStr = cfile.errorString();
+        return false;
+    }
+    return true;
+#endif
+}
+
+bool QMakeVfs::readFile(const QString &fn, QString *contents, QString *errStr)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::ConstIterator it = m_files.constFind(fn);
+    if (it != m_files.constEnd()) {
+        if (it->constData() == m_magicMissing.constData()) {
+            *errStr = fL1S("No such file or directory");
+            return false;
+        }
+        if (it->constData() != m_magicExisting.constData()) {
+            *contents = *it;
+            return true;
+        }
+    }
+#endif
+
+    QFile file(fn);
+    if (!file.open(QIODevice::ReadOnly)) {
+#ifndef PROEVALUATOR_FULL
+        if (!IoUtils::exists(fn)) {
+            m_files[fn] = m_magicMissing;
+            *errStr = fL1S("No such file or directory");
+        } else
+#endif
+            *errStr = file.errorString();
+        return false;
+    }
+#ifndef PROEVALUATOR_FULL
+    m_files[fn] = m_magicExisting;
+#endif
+
+    QByteArray bcont = file.readAll();
+    if (bcont.startsWith("\xef\xbb\xbf")) {
+        // UTF-8 BOM will cause subtle errors
+        *errStr = fL1S("Unexpected UTF-8 BOM");
+        return false;
+    }
+    *contents = QString::fromLocal8Bit(bcont);
+    return true;
+}
+
+bool QMakeVfs::exists(const QString &fn)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::ConstIterator it = m_files.constFind(fn);
+    if (it != m_files.constEnd())
+        return it->constData() != m_magicMissing.constData();
+#endif
+    bool ex = IoUtils::exists(fn);
+#ifndef PROEVALUATOR_FULL
+    m_files[fn] = ex ? m_magicExisting : m_magicMissing;
+#endif
+    return ex;
+}
+
+#ifndef PROEVALUATOR_FULL
+// This should be called when the sources may have changed (e.g., VCS update).
+void QMakeVfs::invalidateCache()
+{
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::Iterator it = m_files.begin(), eit = m_files.end();
+    while (it != eit) {
+        if (it->constData() == m_magicMissing.constData()
+                ||it->constData() == m_magicExisting.constData())
+            it = m_files.erase(it);
+        else
+            ++it;
+    }
+}
+
+// This should be called when generated files may have changed (e.g., actual build).
+void QMakeVfs::invalidateContents()
+{
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    m_files.clear();
+}
+#endif
+
+QT_END_NAMESPACE
diff --git a/src/linguist/shared/qmakevfs.h b/src/linguist/shared/qmakevfs.h
new file mode 100644
index 000000000..c5e77ed94
--- /dev/null
+++ b/src/linguist/shared/qmakevfs.h
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Linguist 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QMAKEVFS_H
+#define QMAKEVFS_H
+
+#include "qmake_global.h"
+
+# include <qiodevice.h>
+#ifndef PROEVALUATOR_FULL
+# include <qhash.h>
+# include <qstring.h>
+# ifdef PROEVALUATOR_THREAD_SAFE
+#  include <qmutex.h>
+# endif
+#endif
+
+QT_BEGIN_NAMESPACE
+
+class QMAKE_EXPORT QMakeVfs
+{
+public:
+    QMakeVfs();
+
+    bool writeFile(const QString &fn, QIODevice::OpenMode mode, const QString &contents, QString *errStr);
+    bool readFile(const QString &fn, QString *contents, QString *errStr);
+    bool exists(const QString &fn);
+
+#ifndef PROEVALUATOR_FULL
+    void invalidateCache();
+    void invalidateContents();
+#endif
+
+private:
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutex m_mutex;
+# endif
+    QHash<QString, QString> m_files;
+    QString m_magicMissing;
+    QString m_magicExisting;
+#endif
+};
+
+QT_END_NAMESPACE
+
+#endif // QMAKEVFS_H