Bug 90521 [Import/Export] NumberFormatException during import zip file
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/TarInputStream.java
int ret = super.read(header, 512 - bytestoread, bytestoread);
			if( ret < 0 ) {
				throw new IOException("early end of stream"); 
			}
			bytestoread -= ret;
			bytesread += ret;
		}
		
		if(headerChecksum(header) == 0) {
			
			if(filepos > 0) {
				return null;
			}
			
			
			throw new TarException("not in tar format"); 
		}
		
		
		if(!isValidTarHeader(header)) {
			throw new TarException("not in tar format"); 
		}
		StringBuffer name = new StringBuffer();
		while(pos < 100 && header[pos] != 0) {
			name.append((char) (header[pos] & 0xff));
			pos++;
		}
		
		pos = 345;
		if(header[pos] != 0) {