Improved error reporting

src/map/atlas.cpp

@@ -112,7 +112,7 @@ Atlas::Atlas(const QString &fileName, bool TAR, const Projection &proj,
 
 	if (TAR) {
 		if (!tar.open()) {
-			_errorString = "Error reading tar file";
+			_errorString = "Error reading tar file: " + tar.errorString();
 			return;
 		}
 		QString tbaFileName(tbaFile(tar.files()));

src/map/mbtilesmap.cpp

@@ -82,6 +82,11 @@ bool MBTilesMap::getZooms()
 			_zooms.append(i);
 	}
 
+	if (!_zooms.size()) {
+		_errorString = "Empty tile set";
+		return false;
+	}
+
 	_zi = _zooms.size() - 1;
 
 	return true;

src/map/ozf.cpp

@@ -179,20 +179,22 @@ bool OZF::readTileTable()
 
 bool OZF::open()
 {
-	if (!_file.open(QIODevice::ReadOnly))
+	if (!_file.open(QIODevice::ReadOnly)) {
+		_error = _file.errorString();
 		return false;
+	}
 
 	if (!_zooms.isEmpty())
 		return true;
 
 	if (!readHeaders()) {
-		qWarning("%s: Invalid header", qPrintable(_file.fileName()));
+		_error = "Invalid header";
 		_file.close();
 		return false;
 	}
 
 	if (!readTileTable()) {
-		qWarning("%s: Invalid tile table", qPrintable(_file.fileName()));
+		_error = "Invalid tile table";
 		_file.close();
 		return false;
 	}

src/map/ozf.h

@@ -17,6 +17,7 @@ public:
 
 	bool open();
 	void close() {_file.close();}
+	const QString &errorString() const {return _error;}
 
 	QString fileName() const {return _file.fileName();}
 	bool isOpen() const {return _file.isOpen();}
@@ -49,6 +50,7 @@ private:
 	quint8 _key;
 	QList<Zoom> _zooms;
 	QFile _file;
+	QString _error;
 };
 
 #endif // OZF_H

src/map/ozimap.cpp

@@ -66,7 +66,7 @@ OziMap::OziMap(const QString &fileName, const Projection &proj, QObject *parent)
 
 		_tar = new Tar(fileName);
 		if (!_tar->open()) {
-			_errorString = "Error reading tar file";
+			_errorString = "Error reading tar file: " + _tar->errorString();
 			return;
 		}
 		QStringList files(_tar->files());
@@ -202,7 +202,7 @@ OziMap::OziMap(const QString &dirName, Tar &tar, const Projection &proj,
 	}
 	_tar = new Tar(tf);
 	if (!_tar->open()) {
-		_errorString = _tar->fileName() + ": error reading tar file";
+		_errorString = _tar->fileName() + ": " + _tar->errorString();
 		return;
 	}
 	if (!setTileInfo(_tar->files())) {
@@ -245,8 +245,8 @@ bool OziMap::setImageInfo(const QString &path)
 
 	if (OZF::isOZF(_map.path)) {
 		_ozf = new OZF(_map.path);
-		if (!_ozf || !_ozf->open()) {
-			_errorString = QString("%1: Error loading OZF file").arg(_map.path);
+		if (!_ozf->open()) {
+			_errorString = QString("%1: %2").arg(_map.path, _ozf->errorString());
 			return false;
 		}
 		_scale = _ozf->scale(_zoom);
@@ -312,19 +312,24 @@ void OziMap::load(const Projection &in, const Projection &out,
 
 	if (_tar) {
 		Q_ASSERT(!_tar->isOpen());
-		if (!_tar->open())
+		if (!_tar->open()) {
+			qWarning("%s: %s", qPrintable(_tar->fileName()),
+			  qPrintable(_tar->errorString()));
 			return;
+		}
 	}
 	if (_ozf) {
 		Q_ASSERT(!_ozf->isOpen());
-		if (!_ozf->open())
+		if (!_ozf->open()) {
+			qWarning("%s: %s", qPrintable(_ozf->fileName()),
+			  qPrintable(_ozf->errorString()));
 			return;
+		}
 	}
 	if (!_tile.isValid() && !_ozf) {
 		Q_ASSERT(!_img);
 		_img = new Image(_map.path);
-		if (_img)
-			_img->setDevicePixelRatio(_mapRatio);
+		_img->setDevicePixelRatio(_mapRatio);
 	}
 }
 

src/map/tar.cpp

@@ -46,8 +46,10 @@ static quint64 number(const char* data, size_t size, int base = 8)
 
 bool Tar::open()
 {
-	if (!_file.open(QIODevice::ReadOnly))
+	if (!_file.open(QIODevice::ReadOnly)) {
+		_error = _file.errorString();
 		return false;
+	}
 
 	if (!_index.isEmpty())
 		return true;
@@ -72,6 +74,7 @@ bool Tar::loadTar()
 		if (ret < BLOCKSIZE) {
 			_file.close();
 			_index.clear();
+			_error = "Error reading header block";
 			return false;
 		}
 		size = number(hdr->size, sizeof(hdr->size));
@@ -79,6 +82,7 @@ bool Tar::loadTar()
 		if (!_file.seek(_file.pos() + BLOCKCOUNT(size) * BLOCKSIZE)) {
 			_file.close();
 			_index.clear();
+			_error = "Error skipping data blocks";
 			return false;
 		}
 	}

src/map/tar.h

@@ -12,6 +12,7 @@ public:
 
 	bool open();
 	void close() {_file.close();}
+	const QString &errorString() const {return _error;}
 
 	QStringList files() const {return _index.keys();}
 	QByteArray file(const QString &name);
@@ -26,6 +27,7 @@ private:
 
 	QFile _file;
 	QMap<QString, quint64> _index;
+	QString _error;
 };
 
 #endif // TAR_H