Fix compatibility with Tar specification

IB-7877

Signed-off-by: Raul Metsma <[email protected]>

client/CDoc2.cpp

@@ -242,19 +242,23 @@ namespace cdoc20 {
 					return false;
 			}
 			Header eof{};
-			return io->write((const char*)&eof, Header::Size) == Header::Size;
+			return io->write((const char*)&eof, Header::Size) == Header::Size &&
+				io->write((const char*)&eof, Header::Size) == Header::Size;
 		}
 
 		std::vector<CDoc::File> files(bool &warning) const
 		{
 			std::vector<CDoc::File> result;
 			Header h {};
+			auto readHeader = [&h, this] { return io->read((char*)&h, Header::Size) == Header::Size; };
 			while(io->bytesAvailable() > 0)
 			{
-				if(io->read((char*)&h, Header::Size) != Header::Size)
+				if(!readHeader())
 					return {};
 				if(h.isNull())
 				{
+					if(!readHeader() && !h.isNull())
+						return {};
 					warning = io->bytesAvailable() > 0;
 					return result;
 				}
@@ -270,7 +274,7 @@ namespace cdoc20 {
 					if(paxData.size() != f.size)
 						return {};
 					io->skip(padding(f.size));
-					if(io->read((char*)&h, Header::Size) != Header::Size || h.isNull() || !h.verify())
+					if(!readHeader() || h.isNull() || !h.verify())
 						return {};
 					f.size = fromOctal(h.size);
 					for(const QByteArray &data: paxData.split('\n'))