Don't read unlimited data from files

It now guards against reading infinite files such as `/dev/zero`.
And most readings are bound with a (lax) limit.
As a side effect, more checking are done when reading a file and
overall the reading procedure is more robust.

PR #19095.

src/base/bittorrent/bencoderesumedatastorage.cpp

@@ -36,6 +36,7 @@
 
 #include <QByteArray>
 #include <QDebug>
+#include <QFile>
 #include <QRegularExpression>
 #include <QThread>
 
@@ -133,17 +134,19 @@ BitTorrent::LoadResumeDataResult BitTorrent::BencodeResumeDataStorage::load(cons
     const Path fastresumePath = path() / Path(idString + u".fastresume");
     const Path torrentFilePath = path() / Path(idString + u".torrent");
 
-    QFile resumeDataFile {fastresumePath.data()};
-    if (!resumeDataFile.open(QIODevice::ReadOnly))
-        return nonstd::make_unexpected(tr("Cannot read file %1: %2").arg(fastresumePath.toString(), resumeDataFile.errorString()));
+    const auto resumeDataReadResult = Utils::IO::readFile(fastresumePath, MAX_TORRENT_SIZE);
+    if (!resumeDataReadResult)
+        return nonstd::make_unexpected(resumeDataReadResult.error().message);
 
-    QFile metadataFile {torrentFilePath.data()};
-    if (metadataFile.exists() && !metadataFile.open(QIODevice::ReadOnly))
-        return nonstd::make_unexpected(tr("Cannot read file %1: %2").arg(torrentFilePath.toString(), metadataFile.errorString()));
-
-    const QByteArray data = resumeDataFile.readAll();
-    const QByteArray metadata = (metadataFile.isOpen() ? metadataFile.readAll() : "");
+    const auto metadataReadResult = Utils::IO::readFile(torrentFilePath, MAX_TORRENT_SIZE);
+    if (!metadataReadResult)
+    {
+        if (metadataReadResult.error().status != Utils::IO::ReadError::NotExist)
+            return nonstd::make_unexpected(metadataReadResult.error().message);
+    }
 
+    const QByteArray data = resumeDataReadResult.value();
+    const QByteArray metadata = metadataReadResult.value_or(QByteArray());
     return loadTorrentResumeData(data, metadata);
 }
 
@@ -161,6 +164,8 @@ void BitTorrent::BencodeResumeDataStorage::doLoadAll() const
 
 void BitTorrent::BencodeResumeDataStorage::loadQueue(const Path &queueFilename)
 {
+    const int lineMaxLength = 48;
+
     QFile queueFile {queueFilename.data()};
     if (!queueFile.exists())
         return;
@@ -175,7 +180,7 @@ void BitTorrent::BencodeResumeDataStorage::loadQueue(const Path &queueFilename)
     int start = 0;
     while (true)
     {
-        const auto line = QString::fromLatin1(queueFile.readLine().trimmed());
+        const auto line = QString::fromLatin1(queueFile.readLine(lineMaxLength).trimmed());
         if (line.isEmpty())
             break;
 

src/base/bittorrent/dbresumedatastorage.cpp

@@ -41,7 +41,6 @@
 
 #include <QByteArray>
 #include <QDebug>
-#include <QFile>
 #include <QMutex>
 #include <QSet>
 #include <QSqlDatabase>

src/base/bittorrent/sessionimpl.cpp

@@ -60,7 +60,6 @@
 
 #include <QDebug>
 #include <QDir>
-#include <QFile>
 #include <QHostAddress>
 #include <QJsonArray>
 #include <QJsonDocument>
@@ -5101,8 +5100,8 @@ void SessionImpl::loadCategories()
 {
     m_categories.clear();
 
-    QFile confFile {(specialFolderLocation(SpecialFolder::Config) / CATEGORIES_FILE_NAME).data()};
-    if (!confFile.exists())
+    const Path path = specialFolderLocation(SpecialFolder::Config) / CATEGORIES_FILE_NAME;
+    if (!path.exists())
     {
         // TODO: Remove the following upgrade code in v4.5
         // == BEGIN UPGRADE CODE ==
@@ -5113,26 +5112,27 @@ void SessionImpl::loadCategories()
 //        return;
     }
 
-    if (!confFile.open(QFile::ReadOnly))
+    const int fileMaxSize = 1024 * 1024;
+    const auto readResult = Utils::IO::readFile(path, fileMaxSize);
+    if (!readResult)
     {
-        LogMsg(tr("Failed to load Categories. File: \"%1\". Error: \"%2\"")
-               .arg(confFile.fileName(), confFile.errorString()), Log::CRITICAL);
+        LogMsg(tr("Failed to load Categories. %1").arg(readResult.error().message), Log::WARNING);
         return;
     }
 
     QJsonParseError jsonError;
-    const QJsonDocument jsonDoc = QJsonDocument::fromJson(confFile.readAll(), &jsonError);
+    const QJsonDocument jsonDoc = QJsonDocument::fromJson(readResult.value(), &jsonError);
     if (jsonError.error != QJsonParseError::NoError)
     {
         LogMsg(tr("Failed to parse Categories configuration. File: \"%1\". Error: \"%2\"")
-               .arg(confFile.fileName(), jsonError.errorString()), Log::WARNING);
+               .arg(path.toString(), jsonError.errorString()), Log::WARNING);
         return;
     }
 
     if (!jsonDoc.isObject())
     {
-        LogMsg(tr("Failed to load Categories configuration. File: \"%1\". Reason: invalid data format")
-               .arg(confFile.fileName()), Log::WARNING);
+        LogMsg(tr("Failed to load Categories configuration. File: \"%1\". Error: \"Invalid data format\"")
+               .arg(path.toString()), Log::WARNING);
         return;
     }
 

src/base/bittorrent/torrentimpl.cpp

@@ -46,7 +46,6 @@
 
 #include <QByteArray>
 #include <QDebug>
-#include <QFile>
 #include <QPointer>
 #include <QSet>
 #include <QStringList>

src/base/bittorrent/torrentinfo.cpp

@@ -103,28 +103,20 @@ nonstd::expected<TorrentInfo, QString> TorrentInfo::load(const QByteArray &data)
 
 nonstd::expected<TorrentInfo, QString> TorrentInfo::loadFromFile(const Path &path) noexcept
 {
-    QFile file {path.data()};
-    if (!file.open(QIODevice::ReadOnly))
-        return nonstd::make_unexpected(file.errorString());
-
-    if (file.size() > MAX_TORRENT_SIZE)
-        return nonstd::make_unexpected(tr("File size exceeds max limit %1").arg(Utils::Misc::friendlyUnit(MAX_TORRENT_SIZE)));
-
     QByteArray data;
     try
     {
-        data = file.readAll();
+        const auto readResult = Utils::IO::readFile(path, MAX_TORRENT_SIZE);
+        if (!readResult)
+            return nonstd::make_unexpected(readResult.error().message);
+        data = readResult.value();
     }
     catch (const std::bad_alloc &e)
     {
-        return nonstd::make_unexpected(tr("Torrent file read error: %1").arg(QString::fromLocal8Bit(e.what())));
+        return nonstd::make_unexpected(tr("Failed to allocate memory when reading file. File: \"%1\". Error: \"%2\"")
+            .arg(path.toString(), QString::fromLocal8Bit(e.what())));
     }
 
-    if (data.size() != file.size())
-        return nonstd::make_unexpected(tr("Torrent file read error: size mismatch"));
-
-    file.close();
-
     return load(data);
 }
 

src/base/rss/feed_serializer.cpp

@@ -31,7 +31,6 @@
 
 #include "feed_serializer.h"
 
-#include <QFile>
 #include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
@@ -46,23 +45,21 @@ const int ARTICLEDATALIST_TYPEID = qRegisterMetaType<QVector<QVariantHash>>();
 
 void RSS::Private::FeedSerializer::load(const Path &dataFileName, const QString &url)
 {
-    QFile file {dataFileName.data()};
+    const int fileMaxSize = 10 * 1024 * 1024;
+    const auto readResult = Utils::IO::readFile(dataFileName, fileMaxSize);
+    if (!readResult)
+    {
+        if (readResult.error().status == Utils::IO::ReadError::NotExist)
+        {
+            emit loadingFinished({});
+            return;
+        }
 
-    if (!file.exists())
-    {
-        emit loadingFinished({});
-    }
-    else if (file.open(QFile::ReadOnly))
-    {
-        emit loadingFinished(loadArticles(file.readAll(), url));
-        file.close();
-    }
-    else
-    {
-        LogMsg(tr("Couldn't read RSS Session data from %1. Error: %2")
-               .arg(dataFileName.toString(), file.errorString())
-               , Log::WARNING);
+        LogMsg(tr("Failed to read RSS session data. %1").arg(readResult.error().message), Log::WARNING);
+        return;
     }
+
+    emit loadingFinished(loadArticles(readResult.value(), url));
 }
 
 void RSS::Private::FeedSerializer::store(const Path &dataFileName, const QVector<QVariantHash> &articlesData)

src/base/rss/rss_autodownloader.cpp

@@ -48,6 +48,7 @@
 #include "../logger.h"
 #include "../profile.h"
 #include "../utils/fs.h"
+#include "../utils/io.h"
 #include "rss_article.h"
 #include "rss_autodownloadrule.h"
 #include "rss_feed.h"
@@ -493,21 +494,21 @@ void AutoDownloader::processJob(const QSharedPointer<ProcessingJob> &job)
 
 void AutoDownloader::load()
 {
-    QFile rulesFile {(m_fileStorage->storageDir() / Path(RULES_FILE_NAME)).data()};
+    const qint64 maxFileSize = 10 * 1024 * 1024;
+    const auto readResult = Utils::IO::readFile((m_fileStorage->storageDir() / Path(RULES_FILE_NAME)), maxFileSize);
+    if (!readResult)
+    {
+        if (readResult.error().status == Utils::IO::ReadError::NotExist)
+        {
+            loadRulesLegacy();
+            return;
+        }
 
-    if (!rulesFile.exists())
-    {
-        loadRulesLegacy();
-    }
-    else if (rulesFile.open(QFile::ReadOnly))
-    {
-        loadRules(rulesFile.readAll());
-    }
-    else
-    {
-        LogMsg(tr("Couldn't read RSS AutoDownloader rules from %1. Error: %2")
-                .arg(rulesFile.fileName(), rulesFile.errorString()), Log::CRITICAL);
+        LogMsg((tr("Failed to read RSS AutoDownloader rules. %1").arg(readResult.error().message)), Log::WARNING);
+        return;
     }
+
+    loadRules(readResult.value());
 }
 
 void AutoDownloader::loadRules(const QByteArray &data)

src/base/rss/rss_session.cpp

@@ -45,6 +45,7 @@
 #include "../profile.h"
 #include "../settingsstorage.h"
 #include "../utils/fs.h"
+#include "../utils/io.h"
 #include "rss_article.h"
 #include "rss_feed.h"
 #include "rss_folder.h"
@@ -261,33 +262,35 @@ Item *Session::itemByPath(const QString &path) const
 
 void Session::load()
 {
-    QFile itemsFile {(m_confFileStorage->storageDir() / Path(FEEDS_FILE_NAME)).data()};
-    if (!itemsFile.exists())
-    {
-        loadLegacy();
-        return;
-    }
+    const int fileMaxSize = 10 * 1024 * 1024;
+    const Path path = m_confFileStorage->storageDir() / Path(FEEDS_FILE_NAME);
 
-    if (!itemsFile.open(QFile::ReadOnly))
+    const auto readResult = Utils::IO::readFile(path, fileMaxSize);
+    if (!readResult)
     {
-        LogMsg(tr("Couldn't read RSS session data. File: \"%1\". Error: \"%2\"")
-            .arg(itemsFile.fileName(), itemsFile.errorString()), Log::WARNING);
+        if (readResult.error().status == Utils::IO::ReadError::NotExist)
+        {
+            loadLegacy();
+            return;
+        }
+
+        LogMsg(tr("Failed to read RSS session data. %1").arg(readResult.error().message), Log::WARNING);
         return;
     }
 
     QJsonParseError jsonError;
-    const QJsonDocument jsonDoc = QJsonDocument::fromJson(itemsFile.readAll(), &jsonError);
+    const QJsonDocument jsonDoc = QJsonDocument::fromJson(readResult.value(), &jsonError);
     if (jsonError.error != QJsonParseError::NoError)
     {
-        LogMsg(tr("Couldn't parse RSS session data. File: \"%1\". Error: \"%2\"")
-            .arg(itemsFile.fileName(), jsonError.errorString()), Log::WARNING);
+        LogMsg(tr("Failed to parse RSS session data. File: \"%1\". Error: \"%2\"")
+            .arg(path.toString(), jsonError.errorString()), Log::WARNING);
         return;
     }
 
     if (!jsonDoc.isObject())
     {
-        LogMsg(tr("Couldn't load RSS session data. File: \"%1\". Error: Invalid data format.")
-            .arg(itemsFile.fileName()), Log::WARNING);
+        LogMsg(tr("Failed to load RSS session data. File: \"%1\". Error: \"Invalid data format.\"")
+            .arg(path.toString()), Log::WARNING);
         return;
     }
 

src/base/search/searchpluginmanager.cpp

@@ -36,6 +36,7 @@
 #include <QDomDocument>
 #include <QDomElement>
 #include <QDomNode>
+#include <QFile>
 #include <QPointer>
 #include <QProcess>
 #include <QUrl>
@@ -517,7 +518,7 @@ void SearchPluginManager::update()
     nova.start(Utils::ForeignApps::pythonInfo().executableName, params, QIODevice::ReadOnly);
     nova.waitForFinished();
 
-    const auto capabilities = QString::fromUtf8(nova.readAll());
+    const auto capabilities = QString::fromUtf8(nova.readAllStandardOutput());
     QDomDocument xmlDoc;
     if (!xmlDoc.setContent(capabilities))
     {
@@ -629,13 +630,15 @@ Path SearchPluginManager::pluginPath(const QString &name)
 
 PluginVersion SearchPluginManager::getPluginVersion(const Path &filePath)
 {
+    const int lineMaxLength = 16;
+
     QFile pluginFile {filePath.data()};
     if (!pluginFile.open(QIODevice::ReadOnly | QIODevice::Text))
         return {};
 
     while (!pluginFile.atEnd())
     {
-        const auto line = QString::fromUtf8(pluginFile.readLine()).remove(u' ');
+        const auto line = QString::fromUtf8(pluginFile.readLine(lineMaxLength)).remove(u' ');
         if (!line.startsWith(u"#VERSION:", Qt::CaseInsensitive)) continue;
 
         const QString versionStr = line.mid(9);

src/base/torrentfileswatcher.cpp

@@ -177,33 +177,35 @@ void TorrentFilesWatcher::initWorker()
 
 void TorrentFilesWatcher::load()
 {
-    QFile confFile {(specialFolderLocation(SpecialFolder::Config) / Path(CONF_FILE_NAME)).data()};
-    if (!confFile.exists())
-    {
-        loadLegacy();
-        return;
-    }
+    const int fileMaxSize = 10 * 1024 * 1024;
+    const Path path = specialFolderLocation(SpecialFolder::Config) / Path(CONF_FILE_NAME);
 
-    if (!confFile.open(QFile::ReadOnly))
+    const auto readResult = Utils::IO::readFile(path, fileMaxSize);
+    if (!readResult)
     {
-        LogMsg(tr("Couldn't load Watched Folders configuration from %1. Error: %2")
-            .arg(confFile.fileName(), confFile.errorString()), Log::WARNING);
+        if (readResult.error().status == Utils::IO::ReadError::NotExist)
+        {
+            loadLegacy();
+            return;
+        }
+
+        LogMsg(tr("Failed to load Watched Folders configuration. %1").arg(readResult.error().message), Log::WARNING);
         return;
     }
 
     QJsonParseError jsonError;
-    const QJsonDocument jsonDoc = QJsonDocument::fromJson(confFile.readAll(), &jsonError);
+    const QJsonDocument jsonDoc = QJsonDocument::fromJson(readResult.value(), &jsonError);
     if (jsonError.error != QJsonParseError::NoError)
     {
-        LogMsg(tr("Couldn't parse Watched Folders configuration from %1. Error: %2")
-            .arg(confFile.fileName(), jsonError.errorString()), Log::WARNING);
+        LogMsg(tr("Failed to parse Watched Folders configuration from %1. Error: \"%2\"")
+            .arg(path.toString(), jsonError.errorString()), Log::WARNING);
         return;
     }
 
     if (!jsonDoc.isObject())
     {
-        LogMsg(tr("Couldn't load Watched Folders configuration from %1. Invalid data format.")
-            .arg(confFile.fileName()), Log::WARNING);
+        LogMsg(tr("Failed to load Watched Folders configuration from %1. Error: \"Invalid data format.\"")
+            .arg(path.toString()), Log::WARNING);
         return;
     }
 
@@ -426,17 +428,26 @@ void TorrentFilesWatcher::Worker::processFolder(const Path &path, const Path &wa
 
         if (filePath.hasExtension(u".magnet"_qs))
         {
+            const int fileMaxSize = 100 * 1024 * 1024;
+
             QFile file {filePath.data()};
             if (file.open(QIODevice::ReadOnly | QIODevice::Text))
             {
-                while (!file.atEnd())
+                if (file.size() <= fileMaxSize)
                 {
-                    const auto line = QString::fromLatin1(file.readLine()).trimmed();
-                    emit magnetFound(BitTorrent::MagnetUri(line), addTorrentParams);
-                }
+                    while (!file.atEnd())
+                    {
+                        const auto line = QString::fromLatin1(file.readLine()).trimmed();
+                        emit magnetFound(BitTorrent::MagnetUri(line), addTorrentParams);
+                    }
 
-                file.close();
-                Utils::Fs::removeFile(filePath);
+                    file.close();
+                    Utils::Fs::removeFile(filePath);
+                }
+                else
+                {
+                    LogMsg(tr("Magnet file too big. File: %1").arg(file.errorString()));
+                }
             }
             else
             {

src/base/utils/io.cpp

@@ -31,7 +31,9 @@
 #include <libtorrent/bencode.hpp>
 #include <libtorrent/entry.hpp>
 
+#include <QCoreApplication>
 #include <QByteArray>
+#include <QFile>
 #include <QFileDevice>
 #include <QSaveFile>
 #include <QString>
@@ -69,6 +71,36 @@ Utils::IO::FileDeviceOutputIterator &Utils::IO::FileDeviceOutputIterator::operat
     return *this;
 }
 
+nonstd::expected<QByteArray, Utils::IO::ReadError> Utils::IO::readFile(const Path &path, const qint64 maxSize, const QIODevice::OpenMode additionalMode)
+{
+    QFile file {path.data()};
+    if (!file.open(QIODevice::ReadOnly | additionalMode))
+    {
+        const QString message = QCoreApplication::translate("Utils::IO", "File open error. File: \"%1\". Error: \"%2\"")
+            .arg(file.fileName(), file.errorString());
+        return nonstd::make_unexpected(ReadError {ReadError::NotExist, message});
+    }
+
+    const qint64 fileSize = file.size();
+    if ((maxSize >= 0) && (fileSize > maxSize))
+    {
+        const QString message = QCoreApplication::translate("Utils::IO", "File size exceeds limit. File: \"%1\". File size: %2. Size limit: %3")
+            .arg(file.fileName(), QString::number(fileSize), QString::number(maxSize));
+        return nonstd::make_unexpected(ReadError {ReadError::ExceedSize, message});
+    }
+
+    // Do not use `QIODevice::readAll()` it won't stop when reading `/dev/zero`
+    const QByteArray data = file.read(fileSize);
+    if (const qint64 dataSize = data.size(); dataSize != fileSize)
+    {
+        const QString message = QCoreApplication::translate("Utils::IO", "Read size mismatch. File: \"%1\". Expected: %2. Actual: %3")
+            .arg(file.fileName(), QString::number(fileSize), QString::number(dataSize));
+        return nonstd::make_unexpected(ReadError {ReadError::SizeMismatch, message});
+    }
+
+    return data;
+}
+
 nonstd::expected<void, QString> Utils::IO::saveToFile(const Path &path, const QByteArray &data)
 {
     if (const Path parentPath = path.parentPath(); !parentPath.isEmpty())

src/base/utils/io.h

@@ -33,6 +33,8 @@
 
 #include <libtorrent/fwd.hpp>
 
+#include <QIODevice>
+
 #include "base/3rdparty/expected.hpp"
 #include "base/pathfwd.h"
 
@@ -81,6 +83,23 @@ namespace Utils::IO
         int m_bufferSize = 0;
     };
 
+    struct ReadError
+    {
+        enum Code
+        {
+            NotExist,
+            ExceedSize,
+            SizeMismatch
+        };
+
+        Code status = {};
+        QString message;
+    };
+
+    // TODO: define a specific type for `additionalMode`
+    // providing `size` is explicit and is strongly recommended
+    nonstd::expected<QByteArray, ReadError> readFile(const Path &path, qint64 size, QIODevice::OpenMode additionalMode = {});
+
     nonstd::expected<void, QString> saveToFile(const Path &path, const QByteArray &data);
     nonstd::expected<void, QString> saveToFile(const Path &path, const lt::entry &data);
 }