feat(logs): parse log4j xml events in logs

Signed-off-by: Rachel Powers <508861+Ryex@users.noreply.github.com>

launcher/CMakeLists.txt

@@ -175,6 +175,8 @@ set(LAUNCH_SOURCES
     launch/LogModel.h
     launch/TaskStepWrapper.cpp
     launch/TaskStepWrapper.h
+    logs/LogParser.cpp
+    logs/LogParser.h
 )
 
 # Old update system

launcher/MessageLevel.cpp

@@ -4,6 +4,8 @@ MessageLevel::Enum MessageLevel::getLevel(const QString& levelName)
 {
     if (levelName == "Launcher")
         return MessageLevel::Launcher;
+    else if (levelName == "Trace")
+        return MessageLevel::Trace;
     else if (levelName == "Debug")
         return MessageLevel::Debug;
     else if (levelName == "Info")

launcher/MessageLevel.h

@@ -12,6 +12,7 @@ enum Enum {
     StdOut,   /**< Undetermined stderr messages */
     StdErr,   /**< Undetermined stdout messages */
     Launcher, /**< Launcher Messages */
+    Trace,    /**< Trace Messages */
     Debug,    /**< Debug Messages */
     Info,     /**< Info Messages */
     Message,  /**< Standard Messages */

launcher/launch/LaunchTask.cpp

@@ -37,11 +37,14 @@
 
 #include "launch/LaunchTask.h"
 #include <assert.h>
+#include <qlogging.h>
+#include <QAnyStringView>
 #include <QCoreApplication>
 #include <QDebug>
 #include <QDir>
 #include <QRegularExpression>
 #include <QStandardPaths>
+#include <variant>
 #include "MessageLevel.h"
 #include "tasks/Task.h"
 
@@ -213,6 +216,52 @@ shared_qobject_ptr<LogModel> LaunchTask::getLogModel()
     return m_logModel;
 }
 
+bool LaunchTask::parseXmlLogs(QString const& line, MessageLevel::Enum level)
+{
+    LogParser* parser;
+    switch (level) {
+        case MessageLevel::StdErr:
+            parser = &m_stderrParser;
+            break;
+        case MessageLevel::StdOut:
+            parser = &m_stdoutParser;
+            break;
+        default:
+            return false;
+    }
+
+    parser->appendLine(line);
+    auto items = parser->parseAvailable();
+    if (auto err = parser->getError(); err.has_value()) {
+        auto& model = *getLogModel();
+        model.append(MessageLevel::Error, tr("[Log4j Parse Error] Failed to parse log4j log event: %1").arg(err.value().errMessage));
+        return false;
+    } else {
+        if (items.has_value()) {
+            auto& model = *getLogModel();
+            for (auto const& item : items.value()) {
+                if (std::holds_alternative<LogParser::LogEntry>(item)) {
+                    auto entry = std::get<LogParser::LogEntry>(item);
+                    auto msg = QString("[%1] [%2/%3] [%4]: %5")
+                                   .arg(entry.timestamp.toString("HH:mm:ss"))
+                                   .arg(entry.thread)
+                                   .arg(entry.levelText)
+                                   .arg(entry.logger)
+                                   .arg(entry.message);
+                    msg = censorPrivateInfo(msg);
+                    model.append(entry.level, msg);
+                } else if (std::holds_alternative<LogParser::PlainText>(item)) {
+                    auto msg = std::get<LogParser::PlainText>(item).message;
+                    level = m_instance->guessLevel(msg, level);
+                    msg = censorPrivateInfo(msg);
+                    model.append(level, msg);
+                }
+            }
+        }
+    }
+    return true;
+}
+
 void LaunchTask::onLogLines(const QStringList& lines, MessageLevel::Enum defaultLevel)
 {
     for (auto& line : lines) {
@@ -222,6 +271,10 @@ void LaunchTask::onLogLines(const QStringList& lines, MessageLevel::Enum default
 
 void LaunchTask::onLogLine(QString line, MessageLevel::Enum level)
 {
+    if (parseXmlLogs(line, level)) {
+        return;
+    }
+
     // if the launcher part set a log level, use it
     auto innerLevel = MessageLevel::fromLine(line);
     if (innerLevel != MessageLevel::Unknown) {
@@ -229,7 +282,7 @@ void LaunchTask::onLogLine(QString line, MessageLevel::Enum level)
     }
 
     // If the level is still undetermined, guess level
-    if (level == MessageLevel::StdErr || level == MessageLevel::StdOut || level == MessageLevel::Unknown) {
+    if (level == MessageLevel::Unknown) {
         level = m_instance->guessLevel(line, level);
     }
 

launcher/launch/LaunchTask.h

@@ -43,6 +43,7 @@
 #include "LaunchStep.h"
 #include "LogModel.h"
 #include "MessageLevel.h"
+#include "logs/LogParser.h"
 
 class LaunchTask : public Task {
     Q_OBJECT
@@ -114,6 +115,9 @@ class LaunchTask : public Task {
    private: /*methods */
     void finalizeSteps(bool successful, const QString& error);
 
+   protected:
+    bool parseXmlLogs(QString const& line, MessageLevel::Enum level);
+
    protected: /* data */
     MinecraftInstancePtr m_instance;
     shared_qobject_ptr<LogModel> m_logModel;
@@ -122,4 +126,6 @@ class LaunchTask : public Task {
     int currentStep = -1;
     State state = NotStarted;
     qint64 m_pid = -1;
+    LogParser m_stdoutParser;
+    LogParser m_stderrParser;
 };

launcher/logs/LogParser.cpp

@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2025 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *
+ *  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, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "LogParser.h"
+
+void LogParser::appendLine(QAnyStringView data)
+{
+    if (!m_partialData.isEmpty()) {
+        m_buffer = QString(m_partialData);
+        m_buffer.append("\n");
+        m_buffer.append(data.toString());
+        m_partialData.clear();
+    } else {
+        m_buffer.append(data.toString());
+    }
+}
+
+std::optional<LogParser::Error> LogParser::getError()
+{
+    return m_error;
+}
+
+MessageLevel::Enum LogParser::parseLogLevel(const QString& level)
+{
+    auto test = level.trimmed().toUpper();
+    if (test == "TRACE") {
+        return MessageLevel::Trace;
+    } else if (test == "DEBUG") {
+        return MessageLevel::Debug;
+    } else if (test == "INFO") {
+        return MessageLevel::Info;
+    } else if (test == "WARN") {
+        return MessageLevel::Warning;
+    } else if (test == "ERROR") {
+        return MessageLevel::Error;
+    } else if (test == "FATAL") {
+        return MessageLevel::Fatal;
+    } else {
+        return MessageLevel::Unknown;
+    }
+}
+
+std::optional<LogParser::LogEntry> LogParser::parseAttributes()
+{
+    LogParser::LogEntry entry{
+        "",
+        MessageLevel::Info,
+    };
+    auto attributes = m_parser.attributes();
+
+    for (const auto& attr : attributes) {
+        auto name = attr.name();
+        auto value = attr.value();
+        if (name == "logger") {
+            entry.logger = value.trimmed().toString();
+        } else if (name == "timestamp") {
+            if (value.trimmed().isEmpty()) {
+                m_parser.raiseError("log4j:Event Missing required attribute: timestamp");
+                return {};
+            }
+            entry.timestamp = QDateTime::fromSecsSinceEpoch(value.trimmed().toLongLong());
+        } else if (name == "level") {
+            entry.levelText = value.trimmed().toString();
+            entry.level = parseLogLevel(entry.levelText);
+        } else if (name == "thread") {
+            entry.thread = value.trimmed().toString();
+        }
+    }
+    if (entry.logger.isEmpty()) {
+        m_parser.raiseError("log4j:Event Missing required attribute: logger");
+        return {};
+    }
+
+    return entry;
+}
+
+void LogParser::setError()
+{
+    m_error = {
+        m_parser.errorString(),
+        m_parser.error(),
+    };
+}
+
+void LogParser::clearError()
+{
+    m_error = {};  // clear previous error
+}
+
+bool isPotentialLog4JStart(QStringView buffer)
+{
+    static QString target = QStringLiteral("<log4j:event");
+    if (buffer.isEmpty() || buffer[0] != '<') {
+        return false;
+    }
+    auto bufLower = buffer.toString().toLower();
+    return target.startsWith(bufLower) || bufLower.startsWith(target);
+}
+
+std::optional<LogParser::ParsedItem> LogParser::parseNext()
+{
+    clearError();
+
+    if (m_buffer.isEmpty()) {
+        return {};
+    }
+
+    if (m_buffer.trimmed().isEmpty()) {
+        m_buffer.clear();
+        return {};
+    }
+
+    // check if we have a full xml log4j event
+    bool isCompleteLog4j = false;
+    m_parser.clear();
+    m_parser.setNamespaceProcessing(false);
+    m_parser.addData(m_buffer);
+    if (m_parser.readNextStartElement()) {
+        if (m_parser.qualifiedName() == "log4j:Event") {
+            int depth = 1;
+            bool eod = false;
+            while (depth > 0 && !eod) {
+                auto tok = m_parser.readNext();
+                switch (tok) {
+                    case QXmlStreamReader::TokenType::StartElement: {
+                        depth += 1;
+                    } break;
+                    case QXmlStreamReader::TokenType::EndElement: {
+                        depth -= 1;
+                    } break;
+                    case QXmlStreamReader::TokenType::EndDocument: {
+                        eod = true;  // break outer while loop
+                    } break;
+                    default: {
+                        // no op
+                    }
+                }
+                if (m_parser.hasError()) {
+                    break;
+                }
+            }
+
+            isCompleteLog4j = depth == 0;
+        }
+    }
+
+    if (isCompleteLog4j) {
+        return parseLog4J();
+    } else {
+        if (isPotentialLog4JStart(m_buffer)) {
+            m_partialData = QString(m_buffer);
+            return LogParser::Partial{ QString(m_buffer) };
+        }
+
+        int start = 0;
+        auto bufView = QStringView(m_buffer);
+        while (start < bufView.length()) {
+            if (qsizetype pos = bufView.right(bufView.length() - start).indexOf('<'); pos != -1) {
+                auto slicestart = start + pos;
+                auto slice = bufView.right(bufView.length() - slicestart);
+                if (isPotentialLog4JStart(slice)) {
+                    if (slicestart > 0) {
+                        auto text = m_buffer.left(slicestart);
+                        m_buffer = m_buffer.right(m_buffer.length() - slicestart);
+                        if (!text.trimmed().isEmpty()) {
+                            return LogParser::PlainText{ text };
+                        }
+                    }
+                    m_partialData = QString(m_buffer);
+                    return LogParser::Partial{ QString(m_buffer) };
+                }
+                start = slicestart + 1;
+            } else {
+                break;
+            }
+        }
+
+        // no log4j found, all plain text
+        auto text = QString(m_buffer);
+        m_buffer.clear();
+        if (text.trimmed().isEmpty()) {
+            return {};
+        } else {
+            return LogParser::PlainText{ text };
+        }
+    }
+}
+
+std::optional<QList<LogParser::ParsedItem>> LogParser::parseAvailable()
+{
+    QList<LogParser::ParsedItem> items;
+    bool doNext = true;
+    while (doNext) {
+        auto item_ = parseNext();
+        if (m_error.has_value()) {
+            return {};
+        }
+        if (item_.has_value()) {
+            auto item = item_.value();
+            if (std::holds_alternative<LogParser::Partial>(item)) {
+                break;
+            } else {
+                items.push_back(item);
+            }
+        } else {
+            doNext = false;
+        }
+    }
+    return items;
+}
+
+std::optional<LogParser::ParsedItem> LogParser::parseLog4J()
+{
+    m_parser.clear();
+    m_parser.setNamespaceProcessing(false);
+    m_parser.addData(m_buffer);
+
+    m_parser.readNextStartElement();
+    if (m_parser.qualifiedName() == "log4j:Event") {
+        auto entry_ = parseAttributes();
+        if (!entry_.has_value()) {
+            setError();
+            return {};
+        }
+        auto entry = entry_.value();
+
+        bool foundMessage = false;
+        int depth = 1;
+
+        while (!m_parser.atEnd()) {
+            auto tok = m_parser.readNext();
+            switch (tok) {
+                case QXmlStreamReader::TokenType::StartElement: {
+                    depth += 1;
+                    if (m_parser.qualifiedName() == "log4j:Message") {
+                        QString message;
+                        bool messageComplete = false;
+
+                        while (!messageComplete) {
+                            auto tok = m_parser.readNext();
+
+                            switch (tok) {
+                                case QXmlStreamReader::TokenType::Characters: {
+                                    message.append(m_parser.text());
+                                } break;
+                                case QXmlStreamReader::TokenType::EndElement: {
+                                    if (m_parser.qualifiedName() == "log4j:Message") {
+                                        messageComplete = true;
+                                    }
+                                } break;
+                                case QXmlStreamReader::TokenType::EndDocument: {
+                                    return {};  // parse fail
+                                } break;
+                                default: {
+                                    // no op
+                                }
+                            }
+
+                            if (m_parser.hasError()) {
+                                return {};
+                            }
+                        }
+
+                        entry.message = message;
+                        foundMessage = true;
+                        depth -= 1;
+                    }
+                    break;
+                    case QXmlStreamReader::TokenType::EndElement: {
+                        depth -= 1;
+                        if (depth == 0 && m_parser.qualifiedName() == "log4j:Event") {
+                            if (foundMessage) {
+                                auto consumed = m_parser.characterOffset();
+                                if (consumed > 0 && consumed <= m_buffer.length()) {
+                                    m_buffer = m_buffer.right(m_buffer.length() - consumed);
+
+                                    if (!m_buffer.isEmpty() && m_buffer.trimmed().isEmpty()) {
+                                        // only whitespace, dump it
+                                        m_buffer.clear();
+                                    }
+                                }
+                                clearError();
+                                return entry;
+                            }
+                            m_parser.raiseError("log4j:Event Missing required attribute: message");
+                            setError();
+                            return {};
+                        }
+                    } break;
+                    case QXmlStreamReader::TokenType::EndDocument: {
+                        return {};
+                    } break;
+                    default: {
+                        // no op
+                    }
+                }
+            }
+
+            if (m_parser.hasError()) {
+                return {};
+            }
+        }
+    }
+
+    throw std::runtime_error("unreachable: already verified this was a complete log4j:Event");
+}

launcher/logs/LogParser.h

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2025 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *
+ *  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, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <QAnyStringView>
+#include <QDateTime>
+#include <QList>
+#include <QString>
+#include <QStringView>
+#include <QXmlStreamReader>
+#include <optional>
+#include <variant>
+#include "MessageLevel.h"
+
+class LogParser {
+   public:
+    struct LogEntry {
+        QString logger;
+        MessageLevel::Enum level;
+        QString levelText;
+        QDateTime timestamp;
+        QString thread;
+        QString message;
+    };
+    struct Partial {
+        QString data;
+    };
+    struct PlainText {
+        QString message;
+    };
+    struct Error {
+        QString errMessage;
+        QXmlStreamReader::Error error;
+    };
+
+    using ParsedItem = std::variant<LogEntry, PlainText, Partial>;
+
+   public:
+    LogParser() = default;
+
+    void appendLine(QAnyStringView data);
+    std::optional<ParsedItem> parseNext();
+    std::optional<QList<ParsedItem>> parseAvailable();
+    std::optional<Error> getError();
+
+   protected:
+    MessageLevel::Enum parseLogLevel(const QString& level);
+    std::optional<LogEntry> parseAttributes();
+    void setError();
+    void clearError();
+
+    std::optional<ParsedItem> parseLog4J();
+
+   private:
+    QString m_buffer;
+    QString m_partialData;
+    QXmlStreamReader m_parser;
+    std::optional<Error> m_error;
+};