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);
 }