12 files changed, 1069 insertions, 0 deletions
diff --git a/libraries/logic/java/JavaChecker.cpp b/libraries/logic/java/JavaChecker.cpp
new file mode 100644
index 00000000..54d552a9
--- /dev/null
+++ b/libraries/logic/java/JavaChecker.cpp
@@ -0,0 +1,159 @@
+#include "JavaChecker.h"
+#include <FileSystem.h>
+#include <Commandline.h>
+#include <QFile>
+#include <QProcess>
+#include <QMap>
+#include <QCoreApplication>
+#include <QDebug>
+
+JavaChecker::JavaChecker(QObject *parent) : QObject(parent)
+{
+}
+
+void JavaChecker::performCheck()
+{
+	QString checkerJar = FS::PathCombine(QCoreApplication::applicationDirPath(), "jars", "JavaCheck.jar");
+
+	QStringList args;
+
+	process.reset(new QProcess());
+	if(m_args.size())
+	{
+		auto extraArgs = Commandline::splitArgs(m_args);
+		args.append(extraArgs);
+	}
+	if(m_minMem != 0)
+	{
+		args << QString("-Xms%1m").arg(m_minMem);
+	}
+	if(m_maxMem != 0)
+	{
+		args << QString("-Xmx%1m").arg(m_maxMem);
+	}
+	if(m_permGen != 64)
+	{
+		args << QString("-XX:PermSize=%1m").arg(m_permGen);
+	}
+
+	args.append({"-jar", checkerJar});
+	process->setArguments(args);
+	process->setProgram(m_path);
+	process->setProcessChannelMode(QProcess::SeparateChannels);
+	qDebug() << "Running java checker: " + m_path + args.join(" ");;
+
+	connect(process.get(), SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(finished(int, QProcess::ExitStatus)));
+	connect(process.get(), SIGNAL(error(QProcess::ProcessError)), this, SLOT(error(QProcess::ProcessError)));
+	connect(process.get(), SIGNAL(readyReadStandardOutput()), this, SLOT(stdoutReady()));
+	connect(process.get(), SIGNAL(readyReadStandardError()), this, SLOT(stderrReady()));
+	connect(&killTimer, SIGNAL(timeout()), SLOT(timeout()));
+	killTimer.setSingleShot(true);
+	killTimer.start(15000);
+	process->start();
+}
+
+void JavaChecker::stdoutReady()
+{
+	QByteArray data = process->readAllStandardOutput();
+	QString added = QString::fromLocal8Bit(data);
+	added.remove('\r');
+	m_stdout += added;
+}
+
+void JavaChecker::stderrReady()
+{
+	QByteArray data = process->readAllStandardError();
+	QString added = QString::fromLocal8Bit(data);
+	added.remove('\r');
+	m_stderr += added;
+}
+
+void JavaChecker::finished(int exitcode, QProcess::ExitStatus status)
+{
+	killTimer.stop();
+	QProcessPtr _process;
+	_process.swap(process);
+
+	JavaCheckResult result;
+	{
+		result.path = m_path;
+		result.id = m_id;
+	}
+	result.errorLog = m_stderr;
+	qDebug() << "STDOUT" << m_stdout;
+	qWarning() << "STDERR" << m_stderr;
+	qDebug() << "Java checker finished with status " << status << " exit code " << exitcode;
+
+	if (status == QProcess::CrashExit || exitcode == 1)
+	{
+		qDebug() << "Java checker failed!";
+		emit checkFinished(result);
+		return;
+	}
+
+	bool success = true;
+
+	QMap<QString, QString> results;
+	QStringList lines = m_stdout.split("\n", QString::SkipEmptyParts);
+	for(QString line : lines)
+	{
+		line = line.trimmed();
+
+		auto parts = line.split('=', QString::SkipEmptyParts);
+		if(parts.size() != 2 || parts[0].isEmpty() || parts[1].isEmpty())
+		{
+			success = false;
+		}
+		else
+		{
+			results.insert(parts[0], parts[1]);
+		}
+	}
+
+	if(!results.contains("os.arch") || !results.contains("java.version") || !success)
+	{
+		qDebug() << "Java checker failed - couldn't extract required information.";
+		emit checkFinished(result);
+		return;
+	}
+
+	auto os_arch = results["os.arch"];
+	auto java_version = results["java.version"];
+	bool is_64 = os_arch == "x86_64" || os_arch == "amd64";
+
+
+	result.valid = true;
+	result.is_64bit = is_64;
+	result.mojangPlatform = is_64 ? "64" : "32";
+	result.realPlatform = os_arch;
+	result.javaVersion = java_version;
+	qDebug() << "Java checker succeeded.";
+	emit checkFinished(result);
+}
+
+void JavaChecker::error(QProcess::ProcessError err)
+{
+	if(err == QProcess::FailedToStart)
+	{
+		killTimer.stop();
+		qDebug() << "Java checker has failed to start.";
+		JavaCheckResult result;
+		{
+			result.path = m_path;
+			result.id = m_id;
+		}
+
+		emit checkFinished(result);
+		return;
+	}
+}
+
+void JavaChecker::timeout()
+{
+	// NO MERCY. NO ABUSE.
+	if(process)
+	{
+		qDebug() << "Java checker has been killed by timeout.";
+		process->kill();
+	}
+}
diff --git a/libraries/logic/java/JavaChecker.h b/libraries/logic/java/JavaChecker.h
new file mode 100644
index 00000000..650e7ce3
--- /dev/null
+++ b/libraries/logic/java/JavaChecker.h
@@ -0,0 +1,54 @@
+#pragma once
+#include <QProcess>
+#include <QTimer>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+#include "JavaVersion.h"
+
+class JavaChecker;
+
+struct MULTIMC_LOGIC_EXPORT JavaCheckResult
+{
+	QString path;
+	QString mojangPlatform;
+	QString realPlatform;
+	JavaVersion javaVersion;
+	QString errorLog;
+	bool valid = false;
+	bool is_64bit = false;
+	int id;
+};
+
+typedef std::shared_ptr<QProcess> QProcessPtr;
+typedef std::shared_ptr<JavaChecker> JavaCheckerPtr;
+class MULTIMC_LOGIC_EXPORT JavaChecker : public QObject
+{
+	Q_OBJECT
+public:
+	explicit JavaChecker(QObject *parent = 0);
+	void performCheck();
+
+	QString m_path;
+	QString m_args;
+	int m_id = 0;
+	int m_minMem = 0;
+	int m_maxMem = 0;
+	int m_permGen = 64;
+
+signals:
+	void checkFinished(JavaCheckResult result);
+private:
+	QProcessPtr process;
+	QTimer killTimer;
+	QString m_stdout;
+	QString m_stderr;
+public
+slots:
+	void timeout();
+	void finished(int exitcode, QProcess::ExitStatus);
+	void error(QProcess::ProcessError);
+	void stdoutReady();
+	void stderrReady();
+};
diff --git a/libraries/logic/java/JavaCheckerJob.cpp b/libraries/logic/java/JavaCheckerJob.cpp
new file mode 100644
index 00000000..0b040e43
--- /dev/null
+++ b/libraries/logic/java/JavaCheckerJob.cpp
@@ -0,0 +1,45 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "JavaCheckerJob.h"
+
+#include <QDebug>
+
+void JavaCheckerJob::partFinished(JavaCheckResult result)
+{
+	num_finished++;
+	qDebug() << m_job_name.toLocal8Bit() << "progress:" << num_finished << "/"
+				<< javacheckers.size();
+	emit progress(num_finished, javacheckers.size());
+
+	javaresults.replace(result.id, result);
+
+	if (num_finished == javacheckers.size())
+	{
+		emit finished(javaresults);
+	}
+}
+
+void JavaCheckerJob::executeTask()
+{
+	qDebug() << m_job_name.toLocal8Bit() << " started.";
+	m_running = true;
+	for (auto iter : javacheckers)
+	{
+		javaresults.append(JavaCheckResult());
+		connect(iter.get(), SIGNAL(checkFinished(JavaCheckResult)), SLOT(partFinished(JavaCheckResult)));
+		iter->performCheck();
+	}
+}
diff --git a/libraries/logic/java/JavaCheckerJob.h b/libraries/logic/java/JavaCheckerJob.h
new file mode 100644
index 00000000..aca0d02e
--- /dev/null
+++ b/libraries/logic/java/JavaCheckerJob.h
@@ -0,0 +1,84 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QtNetwork>
+#include "JavaChecker.h"
+#include "tasks/Task.h"
+
+class JavaCheckerJob;
+typedef std::shared_ptr<JavaCheckerJob> JavaCheckerJobPtr;
+
+class JavaCheckerJob : public Task
+{
+	Q_OBJECT
+public:
+	explicit JavaCheckerJob(QString job_name) : Task(), m_job_name(job_name) {};
+
+	bool addJavaCheckerAction(JavaCheckerPtr base)
+	{
+		javacheckers.append(base);
+		total_progress++;
+		// if this is already running, the action needs to be started right away!
+		if (isRunning())
+		{
+			setProgress(current_progress, total_progress);
+			connect(base.get(), SIGNAL(checkFinished(JavaCheckResult)), SLOT(partFinished(JavaCheckResult)));
+
+			base->performCheck();
+		}
+		return true;
+	}
+
+	JavaCheckerPtr operator[](int index)
+	{
+		return javacheckers[index];
+	}
+	;
+	JavaCheckerPtr first()
+	{
+		if (javacheckers.size())
+			return javacheckers[0];
+		return JavaCheckerPtr();
+	}
+	int size() const
+	{
+		return javacheckers.size();
+	}
+	virtual bool isRunning() const override
+	{
+		return m_running;
+	}
+
+signals:
+	void started();
+	void finished(QList<JavaCheckResult>);
+
+private slots:
+	void partFinished(JavaCheckResult result);
+
+protected:
+	virtual void executeTask() override;
+
+private:
+	QString m_job_name;
+	QList<JavaCheckerPtr> javacheckers;
+	QList<JavaCheckResult> javaresults;
+	qint64 current_progress = 0;
+	qint64 total_progress = 0;
+	int num_finished = 0;
+	bool m_running = false;
+};
diff --git a/libraries/logic/java/JavaInstall.cpp b/libraries/logic/java/JavaInstall.cpp
new file mode 100644
index 00000000..bb262b6e
--- /dev/null
+++ b/libraries/logic/java/JavaInstall.cpp
@@ -0,0 +1,28 @@
+#include "JavaInstall.h"
+#include <MMCStrings.h>
+
+bool JavaInstall::operator<(const JavaInstall &rhs)
+{
+	auto archCompare = Strings::naturalCompare(arch, rhs.arch, Qt::CaseInsensitive);
+	if(archCompare != 0)
+		return archCompare < 0;
+	if(id < rhs.id)
+	{
+		return true;
+	}
+	if(id > rhs.id)
+	{
+		return false;
+	}
+	return Strings::naturalCompare(path, rhs.path, Qt::CaseInsensitive) < 0;
+}
+
+bool JavaInstall::operator==(const JavaInstall &rhs)
+{
+	return arch == rhs.arch && id == rhs.id && path == rhs.path;
+}
+
+bool JavaInstall::operator>(const JavaInstall &rhs)
+{
+	return (!operator<(rhs)) && (!operator==(rhs));
+}
diff --git a/libraries/logic/java/JavaInstall.h b/libraries/logic/java/JavaInstall.h
new file mode 100644
index 00000000..882c7386
--- /dev/null
+++ b/libraries/logic/java/JavaInstall.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include "BaseVersion.h"
+#include "JavaVersion.h"
+
+struct JavaInstall : public BaseVersion
+{
+	JavaInstall(){}
+	JavaInstall(QString id, QString arch, QString path)
+	: id(id), arch(arch), path(path)
+	{
+	}
+	virtual QString descriptor()
+	{
+		return id.toString();
+	}
+
+	virtual QString name()
+	{
+		return id.toString();
+	}
+
+	virtual QString typeString() const
+	{
+		return arch;
+	}
+
+	bool operator<(const JavaInstall & rhs);
+	bool operator==(const JavaInstall & rhs);
+	bool operator>(const JavaInstall & rhs);
+
+	JavaVersion id;
+	QString arch;
+	QString path;
+	bool recommended = false;
+};
+
+typedef std::shared_ptr<JavaInstall> JavaInstallPtr;
diff --git a/libraries/logic/java/JavaInstallList.cpp b/libraries/logic/java/JavaInstallList.cpp
new file mode 100644
index 00000000..c0729227
--- /dev/null
+++ b/libraries/logic/java/JavaInstallList.cpp
@@ -0,0 +1,186 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QtNetwork>
+#include <QtXml>
+#include <QRegExp>
+
+#include <QDebug>
+
+#include "java/JavaInstallList.h"
+#include "java/JavaCheckerJob.h"
+#include "java/JavaUtils.h"
+#include "MMCStrings.h"
+#include "minecraft/VersionFilterData.h"
+
+JavaInstallList::JavaInstallList(QObject *parent) : BaseVersionList(parent)
+{
+}
+
+Task *JavaInstallList::getLoadTask()
+{
+	return new JavaListLoadTask(this);
+}
+
+const BaseVersionPtr JavaInstallList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+bool JavaInstallList::isLoaded()
+{
+	return m_loaded;
+}
+
+int JavaInstallList::count() const
+{
+	return m_vlist.count();
+}
+
+QVariant JavaInstallList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	auto version = std::dynamic_pointer_cast<JavaInstall>(m_vlist[index.row()]);
+	switch (role)
+	{
+		case VersionPointerRole:
+			return qVariantFromValue(m_vlist[index.row()]);
+		case VersionIdRole:
+			return version->descriptor();
+		case VersionRole:
+			return version->id.toString();
+		case RecommendedRole:
+			return version->recommended;
+		case PathRole:
+			return version->path;
+		case ArchitectureRole:
+			return version->arch;
+		default:
+			return QVariant();
+	}
+}
+
+BaseVersionList::RoleList JavaInstallList::providesRoles() const
+{
+	return {VersionPointerRole, VersionIdRole, VersionRole, RecommendedRole, PathRole, ArchitectureRole};
+}
+
+
+void JavaInstallList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	m_vlist = versions;
+	m_loaded = true;
+	sortVersions();
+	if(m_vlist.size())
+	{
+		auto best = std::dynamic_pointer_cast<JavaInstall>(m_vlist[0]);
+		best->recommended = true;
+	}
+	endResetModel();
+}
+
+bool sortJavas(BaseVersionPtr left, BaseVersionPtr right)
+{
+	auto rleft = std::dynamic_pointer_cast<JavaInstall>(left);
+	auto rright = std::dynamic_pointer_cast<JavaInstall>(right);
+	return (*rleft) > (*rright);
+}
+
+void JavaInstallList::sortVersions()
+{
+	beginResetModel();
+	std::sort(m_vlist.begin(), m_vlist.end(), sortJavas);
+	endResetModel();
+}
+
+JavaListLoadTask::JavaListLoadTask(JavaInstallList *vlist) : Task()
+{
+	m_list = vlist;
+	m_currentRecommended = NULL;
+}
+
+JavaListLoadTask::~JavaListLoadTask()
+{
+}
+
+void JavaListLoadTask::executeTask()
+{
+	setStatus(tr("Detecting Java installations..."));
+
+	JavaUtils ju;
+	QList<QString> candidate_paths = ju.FindJavaPaths();
+
+	m_job = std::shared_ptr<JavaCheckerJob>(new JavaCheckerJob("Java detection"));
+	connect(m_job.get(), SIGNAL(finished(QList<JavaCheckResult>)), this, SLOT(javaCheckerFinished(QList<JavaCheckResult>)));
+	connect(m_job.get(), &Task::progress, this, &Task::setProgress);
+
+	qDebug() << "Probing the following Java paths: ";
+	int id = 0;
+	for(QString candidate : candidate_paths)
+	{
+		qDebug() << " " << candidate;
+
+		auto candidate_checker = new JavaChecker();
+		candidate_checker->m_path = candidate;
+		candidate_checker->m_id = id;
+		m_job->addJavaCheckerAction(JavaCheckerPtr(candidate_checker));
+
+		id++;
+	}
+
+	m_job->start();
+}
+
+void JavaListLoadTask::javaCheckerFinished(QList<JavaCheckResult> results)
+{
+	QList<JavaInstallPtr> candidates;
+
+	qDebug() << "Found the following valid Java installations:";
+	for(JavaCheckResult result : results)
+	{
+		if(result.valid)
+		{
+			JavaInstallPtr javaVersion(new JavaInstall());
+
+			javaVersion->id = result.javaVersion;
+			javaVersion->arch = result.mojangPlatform;
+			javaVersion->path = result.path;
+			candidates.append(javaVersion);
+
+			qDebug() << " " << javaVersion->id.toString() << javaVersion->arch << javaVersion->path;
+		}
+	}
+
+	QList<BaseVersionPtr> javas_bvp;
+	for (auto java : candidates)
+	{
+		//qDebug() << java->id << java->arch << " at " << java->path;
+		BaseVersionPtr bp_java = std::dynamic_pointer_cast<BaseVersion>(java);
+
+		if (bp_java)
+		{
+			javas_bvp.append(java);
+		}
+	}
+
+	m_list->updateListData(javas_bvp);
+	emitSucceeded();
+}
diff --git a/libraries/logic/java/JavaInstallList.h b/libraries/logic/java/JavaInstallList.h
new file mode 100644
index 00000000..cf0e5784
--- /dev/null
+++ b/libraries/logic/java/JavaInstallList.h
@@ -0,0 +1,71 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QAbstractListModel>
+
+#include "BaseVersionList.h"
+#include "tasks/Task.h"
+
+#include "JavaCheckerJob.h"
+#include "JavaInstall.h"
+
+#include "multimc_logic_export.h"
+
+class JavaListLoadTask;
+
+class MULTIMC_LOGIC_EXPORT JavaInstallList : public BaseVersionList
+{
+	Q_OBJECT
+public:
+	explicit JavaInstallList(QObject *parent = 0);
+
+	virtual Task *getLoadTask() override;
+	virtual bool isLoaded() override;
+	virtual const BaseVersionPtr at(int i) const override;
+	virtual int count() const override;
+	virtual void sortVersions() override;
+
+	virtual QVariant data(const QModelIndex &index, int role) const override;
+	virtual RoleList providesRoles() const override;
+
+public slots:
+	virtual void updateListData(QList<BaseVersionPtr> versions) override;
+
+protected:
+	QList<BaseVersionPtr> m_vlist;
+
+	bool m_loaded = false;
+};
+
+class JavaListLoadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit JavaListLoadTask(JavaInstallList *vlist);
+	~JavaListLoadTask();
+
+	virtual void executeTask();
+public slots:
+	void javaCheckerFinished(QList<JavaCheckResult> results);
+
+protected:
+	std::shared_ptr<JavaCheckerJob> m_job;
+	JavaInstallList *m_list;
+	JavaInstall *m_currentRecommended;
+};
diff --git a/libraries/logic/java/JavaUtils.cpp b/libraries/logic/java/JavaUtils.cpp
new file mode 100644
index 00000000..88996e9f
--- /dev/null
+++ b/libraries/logic/java/JavaUtils.cpp
@@ -0,0 +1,219 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QStringList>
+#include <QString>
+#include <QDir>
+#include <QStringList>
+
+#include <settings/Setting.h>
+
+#include <QDebug>
+#include "java/JavaUtils.h"
+#include "java/JavaCheckerJob.h"
+#include "java/JavaInstallList.h"
+#include "FileSystem.h"
+
+JavaUtils::JavaUtils()
+{
+}
+
+JavaInstallPtr JavaUtils::MakeJavaPtr(QString path, QString id, QString arch)
+{
+	JavaInstallPtr javaVersion(new JavaInstall());
+
+	javaVersion->id = id;
+	javaVersion->arch = arch;
+	javaVersion->path = path;
+
+	return javaVersion;
+}
+
+JavaInstallPtr JavaUtils::GetDefaultJava()
+{
+	JavaInstallPtr javaVersion(new JavaInstall());
+
+	javaVersion->id = "java";
+	javaVersion->arch = "unknown";
+	javaVersion->path = "java";
+
+	return javaVersion;
+}
+
+#if defined(Q_OS_WIN32)
+QList<JavaInstallPtr> JavaUtils::FindJavaFromRegistryKey(DWORD keyType, QString keyName)
+{
+	QList<JavaInstallPtr> javas;
+
+	QString archType = "unknown";
+	if (keyType == KEY_WOW64_64KEY)
+		archType = "64";
+	else if (keyType == KEY_WOW64_32KEY)
+		archType = "32";
+
+	HKEY jreKey;
+	if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, keyName.toStdString().c_str(), 0,
+					  KEY_READ | keyType | KEY_ENUMERATE_SUB_KEYS, &jreKey) == ERROR_SUCCESS)
+	{
+		// Read the current type version from the registry.
+		// This will be used to find any key that contains the JavaHome value.
+		char *value = new char[0];
+		DWORD valueSz = 0;
+		if (RegQueryValueExA(jreKey, "CurrentVersion", NULL, NULL, (BYTE *)value, &valueSz) ==
+			ERROR_MORE_DATA)
+		{
+			value = new char[valueSz];
+			RegQueryValueExA(jreKey, "CurrentVersion", NULL, NULL, (BYTE *)value, &valueSz);
+		}
+
+		QString recommended = value;
+
+		TCHAR subKeyName[255];
+		DWORD subKeyNameSize, numSubKeys, retCode;
+
+		// Get the number of subkeys
+		RegQueryInfoKey(jreKey, NULL, NULL, NULL, &numSubKeys, NULL, NULL, NULL, NULL, NULL,
+						NULL, NULL);
+
+		// Iterate until RegEnumKeyEx fails
+		if (numSubKeys > 0)
+		{
+			for (int i = 0; i < numSubKeys; i++)
+			{
+				subKeyNameSize = 255;
+				retCode = RegEnumKeyEx(jreKey, i, subKeyName, &subKeyNameSize, NULL, NULL, NULL,
+									   NULL);
+				if (retCode == ERROR_SUCCESS)
+				{
+					// Now open the registry key for the version that we just got.
+					QString newKeyName = keyName + "\\" + subKeyName;
+
+					HKEY newKey;
+					if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, newKeyName.toStdString().c_str(), 0,
+									 KEY_READ | KEY_WOW64_64KEY, &newKey) == ERROR_SUCCESS)
+					{
+						// Read the JavaHome value to find where Java is installed.
+						value = new char[0];
+						valueSz = 0;
+						if (RegQueryValueEx(newKey, "JavaHome", NULL, NULL, (BYTE *)value,
+											&valueSz) == ERROR_MORE_DATA)
+						{
+							value = new char[valueSz];
+							RegQueryValueEx(newKey, "JavaHome", NULL, NULL, (BYTE *)value,
+											&valueSz);
+
+							// Now, we construct the version object and add it to the list.
+							JavaInstallPtr javaVersion(new JavaInstall());
+
+							javaVersion->id = subKeyName;
+							javaVersion->arch = archType;
+							javaVersion->path =
+								QDir(FS::PathCombine(value, "bin")).absoluteFilePath("javaw.exe");
+							javas.append(javaVersion);
+						}
+
+						RegCloseKey(newKey);
+					}
+				}
+			}
+		}
+
+		RegCloseKey(jreKey);
+	}
+
+	return javas;
+}
+
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	QList<JavaInstallPtr> java_candidates;
+
+	QList<JavaInstallPtr> JRE64s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_64KEY, "SOFTWARE\\JavaSoft\\Java Runtime Environment");
+	QList<JavaInstallPtr> JDK64s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_64KEY, "SOFTWARE\\JavaSoft\\Java Development Kit");
+	QList<JavaInstallPtr> JRE32s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_32KEY, "SOFTWARE\\JavaSoft\\Java Runtime Environment");
+	QList<JavaInstallPtr> JDK32s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_32KEY, "SOFTWARE\\JavaSoft\\Java Development Kit");
+
+	java_candidates.append(JRE64s);
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre6/bin/javaw.exe"));
+	java_candidates.append(JDK64s);
+	java_candidates.append(JRE32s);
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre6/bin/javaw.exe"));
+	java_candidates.append(JDK32s);
+	java_candidates.append(MakeJavaPtr(this->GetDefaultJava()->path));
+
+	QList<QString> candidates;
+	for(JavaInstallPtr java_candidate : java_candidates)
+	{
+		if(!candidates.contains(java_candidate->path))
+		{
+			candidates.append(java_candidate->path);
+		}
+	}
+
+	return candidates;
+}
+
+#elif defined(Q_OS_MAC)
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+	javas.append("/Applications/Xcode.app/Contents/Applications/Application Loader.app/Contents/MacOS/itms/java/bin/java");
+	javas.append("/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java");
+	javas.append("/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java");
+	QDir libraryJVMDir("/Library/Java/JavaVirtualMachines/");
+	QStringList libraryJVMJavas = libraryJVMDir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
+	foreach (const QString &java, libraryJVMJavas) {
+		javas.append(libraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/bin/java");
+		javas.append(libraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/jre/bin/java");
+	}
+	QDir systemLibraryJVMDir("/System/Library/Java/JavaVirtualMachines/");
+	QStringList systemLibraryJVMJavas = systemLibraryJVMDir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
+	foreach (const QString &java, systemLibraryJVMJavas) {
+		javas.append(systemLibraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/bin/java");
+		javas.append(systemLibraryJVMDir.absolutePath() + "/" + java + "/Contents/Commands/java");
+	}
+	return javas;
+}
+
+#elif defined(Q_OS_LINUX)
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	qDebug() << "Linux Java detection incomplete - defaulting to \"java\"";
+
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+    javas.append("/opt/java/bin/java");
+    javas.append("/usr/bin/java");
+
+	return javas;
+}
+#else
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	qDebug() << "Unknown operating system build - defaulting to \"java\"";
+
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+
+	return javas;
+}
+#endif
diff --git a/libraries/logic/java/JavaUtils.h b/libraries/logic/java/JavaUtils.h
new file mode 100644
index 00000000..3fb88341
--- /dev/null
+++ b/libraries/logic/java/JavaUtils.h
@@ -0,0 +1,43 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QStringList>
+
+#include "JavaCheckerJob.h"
+#include "JavaChecker.h"
+#include "JavaInstallList.h"
+
+#ifdef Q_OS_WIN
+#include <windows.h>
+#endif
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT JavaUtils : public QObject
+{
+	Q_OBJECT
+public:
+	JavaUtils();
+
+	JavaInstallPtr MakeJavaPtr(QString path, QString id = "unknown", QString arch = "unknown");
+	QList<QString> FindJavaPaths();
+	JavaInstallPtr GetDefaultJava();
+
+#ifdef Q_OS_WIN
+	QList<JavaInstallPtr> FindJavaFromRegistryKey(DWORD keyType, QString keyName);
+#endif
+};
diff --git a/libraries/logic/java/JavaVersion.cpp b/libraries/logic/java/JavaVersion.cpp
new file mode 100644
index 00000000..84fc48a4
--- /dev/null
+++ b/libraries/logic/java/JavaVersion.cpp
@@ -0,0 +1,112 @@
+#include "JavaVersion.h"
+#include <MMCStrings.h>
+
+#include <QRegularExpression>
+#include <QString>
+
+JavaVersion & JavaVersion::operator=(const QString & javaVersionString)
+{
+	string = javaVersionString;
+
+	auto getCapturedInteger = [](const QRegularExpressionMatch & match, const QString &what) -> int
+	{
+		auto str = match.captured(what);
+		if(str.isEmpty())
+		{
+			return 0;
+		}
+		return str.toInt();
+	};
+
+	QRegularExpression pattern;
+	if(javaVersionString.startsWith("1."))
+	{
+		pattern = QRegularExpression ("1[.](?<major>[0-9]+)([.](?<minor>[0-9]+))?(_(?<security>[0-9]+)?)?(-(?<prerelease>[a-zA-Z0-9]+))?");
+	}
+	else
+	{
+		pattern = QRegularExpression("(?<major>[0-9]+)([.](?<minor>[0-9]+))?([.](?<security>[0-9]+))?(-(?<prerelease>[a-zA-Z0-9]+))?");
+	}
+
+	auto match = pattern.match(string);
+	parseable = match.hasMatch();
+	major = getCapturedInteger(match, "major");
+	minor = getCapturedInteger(match, "minor");
+	security = getCapturedInteger(match, "security");
+	prerelease = match.captured("prerelease");
+	return *this;
+}
+
+JavaVersion::JavaVersion(const QString &rhs)
+{
+	operator=(rhs);
+}
+
+QString JavaVersion::toString()
+{
+	return string;
+}
+
+bool JavaVersion::requiresPermGen()
+{
+	if(parseable)
+	{
+		return major < 8;
+	}
+	return true;
+}
+
+bool JavaVersion::operator<(const JavaVersion &rhs)
+{
+	if(parseable && rhs.parseable)
+	{
+		if(major < rhs.major)
+			return true;
+		if(major > rhs.major)
+			return false;
+		if(minor < rhs.minor)
+			return true;
+		if(minor > rhs.minor)
+			return false;
+		if(security < rhs.security)
+			return true;
+		if(security > rhs.security)
+			return false;
+
+		// everything else being equal, consider prerelease status
+		bool thisPre = !prerelease.isEmpty();
+		bool rhsPre = !rhs.prerelease.isEmpty();
+		if(thisPre && !rhsPre)
+		{
+			// this is a prerelease and the other one isn't -> lesser
+			return true;
+		}
+		else if(!thisPre && rhsPre)
+		{
+			// this isn't a prerelease and the other one is -> greater
+			return false;
+		}
+		else if(thisPre && rhsPre)
+		{
+			// both are prereleases - use natural compare...
+			return Strings::naturalCompare(prerelease, rhs.prerelease, Qt::CaseSensitive) < 0;
+		}
+		// neither is prerelease, so they are the same -> this cannot be less than rhs
+		return false;
+	}
+	else return Strings::naturalCompare(string, rhs.string, Qt::CaseSensitive) < 0;
+}
+
+bool JavaVersion::operator==(const JavaVersion &rhs)
+{
+	if(parseable && rhs.parseable)
+	{
+		return major == rhs.major && minor == rhs.minor && security == rhs.security && prerelease == rhs.prerelease;
+	}
+	return string == rhs.string;
+}
+
+bool JavaVersion::operator>(const JavaVersion &rhs)
+{
+	return (!operator<(rhs)) && (!operator==(rhs));
+}
diff --git a/libraries/logic/java/JavaVersion.h b/libraries/logic/java/JavaVersion.h
new file mode 100644
index 00000000..f9a733d3
--- /dev/null
+++ b/libraries/logic/java/JavaVersion.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "multimc_logic_export.h"
+#include <QString>
+
+class MULTIMC_LOGIC_EXPORT JavaVersion
+{
+	friend class JavaVersionTest;
+public:
+	JavaVersion() {};
+	JavaVersion(const QString & rhs);
+
+	JavaVersion & operator=(const QString & rhs);
+
+	bool operator<(const JavaVersion & rhs);
+	bool operator==(const JavaVersion & rhs);
+	bool operator>(const JavaVersion & rhs);
+
+	bool requiresPermGen();
+
+	QString toString();
+
+private:
+	QString string;
+	int major = 0;
+	int minor = 0;
+	int security = 0;
+	bool parseable = false;
+	QString prerelease;
+};