From 8f799e1bcf169bd3ddc516c8c052715466d5d356 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20T=C5=AFma?= <tumic@cbox.cz>
Date: Sun, 12 May 2019 01:23:18 +0200
Subject: [PATCH] Fixed possible crash when the cache wouldn't accept the new
 item

---
 src/map/IMG/img.cpp     | 20 +++++++++-----------
 src/map/IMG/img.h       |  2 +-
 src/map/IMG/subfile.cpp |  3 +--
 3 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/src/map/IMG/img.cpp b/src/map/IMG/img.cpp
index 1f901deb..6f08eae8 100644
--- a/src/map/IMG/img.cpp
+++ b/src/map/IMG/img.cpp
@@ -230,20 +230,18 @@ template<class T> bool IMG::readValue(T &val)
 	return true;
 }
 
-QByteArray IMG::readBlock(int blockNum)
+bool IMG::readBlock(int blockNum, QByteArray &data)
 {
 	QByteArray *block = _blockCache[blockNum];
 	if (!block) {
 		if (!_file.seek((qint64)blockNum * (qint64)_blockSize))
-			return QByteArray();
-		QByteArray *ba = new QByteArray();
-		ba->resize(_blockSize);
-		if (read(ba->data(), _blockSize) < _blockSize) {
-			delete ba;
-			return QByteArray();
-		}
-		_blockCache.insert(blockNum, ba);
-		return *ba;
+			return false;
+		data.resize(_blockSize);
+		if (read(data.data(), _blockSize) < _blockSize)
+			return false;
+		_blockCache.insert(blockNum, new QByteArray(data));
 	} else
-		return *block;
+		data = *block;
+
+	return true;
 }
diff --git a/src/map/IMG/img.h b/src/map/IMG/img.h
index 736aa8e9..f479bd9b 100644
--- a/src/map/IMG/img.h
+++ b/src/map/IMG/img.h
@@ -65,7 +65,7 @@ private:
 	typedef RTree<VectorTile*, double, 2> TileTree;
 
 	int blockSize() const {return _blockSize;}
-	QByteArray readBlock(int blockNum);
+	bool readBlock(int blockNum, QByteArray &data);
 	qint64 read(char *data, qint64 maxSize);
 	template<class T> bool readValue(T &val);
 
diff --git a/src/map/IMG/subfile.cpp b/src/map/IMG/subfile.cpp
index b8991ec1..12ccdf80 100644
--- a/src/map/IMG/subfile.cpp
+++ b/src/map/IMG/subfile.cpp
@@ -33,8 +33,7 @@ bool SubFile::seek(Handle &handle, quint32 pos) const
 	if (handle.blockNum != blockNum) {
 		if (blockNum >= _blocks.size())
 			return false;
-		handle.data = _img->readBlock(_blocks.at(blockNum));
-		if (handle.data.isNull())
+		if (!_img->readBlock(_blocks.at(blockNum), handle.data))
 			return false;
 		handle.blockNum = blockNum;
 	}