Implemented temp_folder() function.

include/MUtils/Global.h

@@ -32,4 +32,19 @@ namespace MUtils
 	QString rand_str(const bool &bLong = false);
 	quint32 next_rand32(void);
 	quint64 next_rand64(void);
+
+	//Temp Folder
+	const QString &temp_folder(void);
 }
+
+///////////////////////////////////////////////////////////////////////////////
+
+#define MUTILS_DELETE(PTR) do \
+{ \
+	if((PTR)) \
+	{ \
+		delete (PTR); \
+		(PTR) = NULL; \
+	} \
+} \
+while(0)

src/Global.cpp

@@ -25,6 +25,10 @@
 
 #include <MUtils/Global.h>
 
+//Qt
+#include <QDir>
+#include <QReadWriteLock>
+
 //CRT
 #include <cstdlib>
 #include <ctime>
@@ -91,3 +95,136 @@ QString MUtils::rand_str(const bool &bLong)
 	}
 	return QString("%1%2").arg(rand_str(false), rand_str(false));
 }
+
+///////////////////////////////////////////////////////////////////////////////
+// TEMP FOLDER
+///////////////////////////////////////////////////////////////////////////////
+
+static QReadWriteLock g_temp_folder_lock;
+static QFile *g_temp_folder_file;
+static QString *g_temp_folder_path = NULL;
+
+#define INIT_TEMP_FOLDER_RAND(OUT_PTR, FILE_PTR, BASE_DIR) do \
+{ \
+	for(int _i = 0; _i < 128; _i++) \
+	{ \
+		const QString _randDir = QString("%1/%2").arg((BASE_DIR), rand_str()); \
+		if(!QDir(_randDir).exists()) \
+		{ \
+			*(OUT_PTR) = try_init_folder(_randDir, (FILE_PTR)); \
+			if(!(OUT_PTR)->isEmpty()) break; \
+		} \
+	} \
+} \
+while(0)
+
+static QString try_init_folder(const QString &folderPath, QFile *&lockFile)
+{
+	static const char *TEST_DATA = "Lorem ipsum dolor sit amet, consectetur, adipisci velit!";
+	
+	bool success = false;
+
+	const QFileInfo folderInfo(folderPath);
+	const QDir folderDir(folderInfo.absoluteFilePath());
+
+	//Remove existing lock file
+	if(lockFile)
+	{
+		lockFile->remove();
+		MUTILS_DELETE(lockFile);
+	}
+
+	//Create folder, if it does *not* exist yet
+	if(!folderDir.exists())
+	{
+		for(int i = 0; i < 16; i++)
+		{
+			if(folderDir.mkpath(".")) break;
+		}
+	}
+
+	//Make sure folder exists now *and* is writable
+	if(folderDir.exists())
+	{
+		const QByteArray testData = QByteArray(TEST_DATA);
+		for(int i = 0; i < 32; i++)
+		{
+			lockFile = new QFile(folderDir.absoluteFilePath(QString("~%1.tmp").arg(MUtils::rand_str())));
+			if(lockFile->open(QIODevice::ReadWrite | QIODevice::Truncate))
+			{
+				if(lockFile->write(testData) >= testData.size())
+				{
+					success = true;
+					break;
+				}
+				lockFile->remove();
+				MUTILS_DELETE(lockFile);
+			}
+		}
+	}
+
+	return (success ? folderDir.canonicalPath() : QString());
+}
+
+const QString &MUtils::temp_folder(void)
+{
+	QReadLocker readLock(&g_temp_folder_lock);
+
+	//Already initialized?
+	if(g_temp_folder_path && (!g_temp_folder_path->isEmpty()))
+	{
+		return (*g_temp_folder_path);
+	}
+
+	//Obtain the write lock to initilaize
+	readLock.unlock();
+	QWriteLocker writeLock(&g_temp_folder_lock);
+	
+	//Still uninitilaized?
+	if(g_temp_folder_path && (!g_temp_folder_path->isEmpty()))
+	{
+		return (*g_temp_folder_path);
+	}
+
+	//Create the string, if not done yet
+	if(!g_temp_folder_path)
+	{
+		g_temp_folder_path = new QString();
+	}
+	
+	g_temp_folder_path->clear();
+
+	//Try the %TMP% or %TEMP% directory first
+	QString tempPath = try_init_folder(QDir::temp().absolutePath(), g_temp_folder_file);
+	if(!tempPath.isEmpty())
+	{
+		INIT_TEMP_FOLDER_RAND(g_temp_folder_path, g_temp_folder_file, tempPath);
+	}
+
+	//Otherwise create TEMP folder in %LOCALAPPDATA% or %SYSTEMROOT%
+	if(g_temp_folder_path->isEmpty())
+	{
+		qWarning("%%TEMP%% directory not found -> trying fallback mode now!");
+		static const lamexp_known_folder_t folderId[2] = { lamexp_folder_localappdata, lamexp_folder_systroot_dir };
+		for(size_t id = 0; (g_lamexp_temp_folder.path->isEmpty() && (id < 2)); id++)
+		{
+			const QString &knownFolder = lamexp_known_folder(folderId[id]);
+			if(!knownFolder.isEmpty())
+			{
+				tempPath = try_init_folder(QString("%1/Temp").arg(knownFolder));
+				if(!tempPath.isEmpty())
+				{
+					INIT_TEMP_FOLDER_RAND(g_temp_folder_path, g_temp_folder_file, tempPath);
+				}
+			}
+		}
+	}
+
+	//Failed to create TEMP folder?
+	if(g_temp_folder_path->isEmpty())
+	{
+		qFatal("Temporary directory could not be initialized !!!");
+	}
+	
+	return (*g_temp_folder_path);
+}