diff base/TempWriteFile.cpp @ 674:920e3880f7b4

* Add TempWriteFile abstraction, use it when exporting audio to avoid clobbering existing file before export is complete

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/TempWriteFile.cpp	Tue Mar 29 17:30:23 2011 +0100
@@ -0,0 +1,69 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Sonic Visualiser
+    An audio file viewer and annotation editor.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#include "TempWriteFile.h"
+
+#include "Exceptions.h"
+
+#include <QTemporaryFile>
+#include <QDir>
+#include <iostream>
+
+TempWriteFile::TempWriteFile(QString target) :
+    m_target(target)
+{
+    QTemporaryFile temp(m_target + ".");
+    temp.setAutoRemove(false);
+    temp.open(); // creates the file and opens it atomically
+    if (temp.error()) {
+	std::cerr << "TempWriteFile: Failed to create temporary file in directory of " << m_target.toStdString() << ": " << temp.errorString().toStdString() << std::endl;
+	throw FileOperationFailed(temp.fileName(), "creation");
+    }
+    
+    m_temp = temp.fileName();
+    temp.close();
+}
+
+TempWriteFile::~TempWriteFile()
+{
+    if (m_temp != "") {
+	QDir dir(QFileInfo(m_temp).dir());
+	dir.remove(m_temp);
+    }
+}
+
+QString
+TempWriteFile::getTemporaryFilename()
+{
+    return m_temp;
+}
+
+void
+TempWriteFile::moveToTarget()
+{
+    if (m_temp == "") return;
+
+    QDir dir(QFileInfo(m_temp).dir());
+    // According to  http://doc.trolltech.com/4.4/qdir.html#rename
+    // some systems fail, if renaming over an existing file.
+    // Therefore, delete first the existing file.
+    if (dir.exists(m_target)) dir.remove(m_target);
+    if (!dir.rename(m_temp, m_target)) {
+	std::cerr << "TempWriteFile: Failed to rename temporary file " << m_temp.toStdString() << " to target " << m_target.toStdString() << std::endl;
+	throw FileOperationFailed(m_temp, "rename");
+    }
+
+    m_temp = "";
+}
+