QStandardPaths implementation configured using JSON

The default JSON file is /etc/user-dirs.json, but may be
overridden by setting PATH_CONFIG_HOME to the file to be used.

This provides functionality similar to the XDG based QStandardPaths,
but uses a JSON file to define paths, rather than the XDG A=B
format. Values other than HomeLocation and TempLocation may be
specified by removing the "Location" postfix, converting to upper
case, and separating words with _. Values are independent. For example,
CacheLocation does not depend on GenericCacheLocation.

Variables specified as ${[^{]*} will be replaced with environment
variables.

Change-Id: I374f5e6bae498dbfa9cb4ecadf915b05fb91fc34
Reviewed-by: David Faure <faure@kde.org>

2 files changed, 186 insertions, 0 deletions

diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index 1a73783604..2df862e360 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -106,6 +106,8 @@ win32 {
         }
         macx-*: {
             SOURCES += io/qstandardpaths_mac.cpp
+        } else:standardpathsjson {
+            SOURCES += io/qstandardpaths_json.cpp
         } else {
             SOURCES += io/qstandardpaths_unix.cpp
         }
diff --git a/src/corelib/io/qstandardpaths_json.cpp b/src/corelib/io/qstandardpaths_json.cpp
new file mode 100644
index 0000000000..52b194bea8
--- /dev/null
+++ b/src/corelib/io/qstandardpaths_json.cpp
@@ -0,0 +1,184 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** 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, Nokia gives you certain additional
+** rights. These rights are described in the Nokia 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "qstandardpaths.h"
+
+#include <QRegExp>
+#include <QString>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonValue>
+#include <QFile>
+#include <QDir>
+#include <QAtomicPointer>
+
+#ifndef QT_NO_STANDARDPATHS
+
+QT_BEGIN_NAMESPACE
+
+class QStandardPathsPrivate {
+public:
+    QStandardPathsPrivate() : object(0){}
+    ~QStandardPathsPrivate() { delete object.load(); }
+    QAtomicPointer<QJsonObject> object;
+};
+
+Q_GLOBAL_STATIC(QStandardPathsPrivate, configCache);
+
+QString QStandardPaths::writableLocation(StandardLocation type)
+{
+    switch (type) {
+    case HomeLocation:
+        return QDir::homePath(); // set $HOME
+    case TempLocation:
+        return QDir::tempPath(); // set $TMPDIR
+    default:
+        break;
+    }
+
+    QJsonObject * localConfigObject = configCache()->object.loadAcquire();
+    if (localConfigObject == 0) {
+        QString configHome = QFile::decodeName(qgetenv("PATH_CONFIG_HOME"));
+        if (configHome.isEmpty())
+            configHome = QLatin1String("/etc/user-dirs.json");
+        QFile file(configHome);
+        if (file.open(QIODevice::ReadOnly)) {
+            QJsonDocument configDoc = QJsonDocument::fromJson(file.readAll());
+            if (configDoc.isNull())
+                return QString();
+
+            QJsonObject myConfigObject = configDoc.object();
+            localConfigObject = new QJsonObject(myConfigObject);
+            if (!configCache()->object.testAndSetRelease(0, localConfigObject)) {
+                delete localConfigObject;
+                localConfigObject = configCache()->object.loadAcquire();
+            }
+        } else {
+            return QString();
+        }
+    }
+
+    QLatin1String key("");
+
+    switch (type) {
+    case DocumentsLocation:
+        key = QLatin1String("DOCUMENTS");
+        break;
+    case PicturesLocation:
+        key = QLatin1String("PICTURES");
+        break;
+    case MusicLocation:
+        key = QLatin1String("MUSIC");
+        break;
+    case MoviesLocation:
+        key = QLatin1String("VIDEOS");
+        break;
+    case DownloadLocation:
+        key = QLatin1String("DOWNLOAD");
+        break;
+    case ApplicationsLocation:
+        key = QLatin1String("APPLICATIONS");
+        break;
+    case CacheLocation:
+        key = QLatin1String("CACHE");
+        break;
+    case GenericCacheLocation:
+        key = QLatin1String("GENERIC_CACHE");
+        break;
+    case DataLocation:
+        key = QLatin1String("DATA");
+        break;
+    case GenericDataLocation:
+        key = QLatin1String("GENERIC_DATA");
+        break;
+    case ConfigLocation:
+        key = QLatin1String("CONFIG");
+        break;
+    case RuntimeLocation:
+        key = QLatin1String("RUNTIME");
+        break;
+    case DesktopLocation:
+        key = QLatin1String("DESKTOP");
+        break;
+    case FontsLocation:
+        key = QLatin1String("FONTS");
+        break;
+
+    default:
+        return QString();
+    }
+
+    QJsonObject::const_iterator iter = localConfigObject->constFind(key);
+    if (iter == localConfigObject->constEnd() || ! iter.value().isString())
+        return QString();
+    QString value = iter.value().toString();
+
+    // optimize for a common case
+    value.replace(QLatin1String("${HOME}"), QFile::decodeName(qgetenv("HOME")));
+
+    // Do ${} format environment variable substitution if necessary
+    if (!value.isEmpty() && value.contains(QLatin1String("${"))) {
+        QRegExp varRegExp(QLatin1String("\\$\\{([^\\}]*)\\}"));
+        while (value.contains(varRegExp)) {
+            QString replacement =
+                    QFile::decodeName(qgetenv(varRegExp.cap(1).toAscii().data()));
+            value.replace(varRegExp.cap(0), replacement);
+        }
+    }
+    return value;
+}
+
+QStringList QStandardPaths::standardLocations(StandardLocation type)
+{
+    QStringList dirs;
+    const QString localDir = writableLocation(type);
+    dirs.prepend(localDir);
+    return dirs;
+}
+
+QString QStandardPaths::displayName(StandardLocation type)
+{
+    Q_UNUSED(type);
+    return QString();
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_STANDARDPATHS