libropkg: implement tar file reader

libropkg/reader.h

@@ -0,0 +1,17 @@
+#ifndef _READER_H_
+#define _READER_H_
+
+#include "tar.h"
+
+#include <blue/compress/cstream.h>
+#include <ropkg/reader.h>
+
+struct ropkg_reader {
+	b_cstream *r_stream;
+	struct ustar_header r_cur_header;
+	size_t r_cur_header_offset;
+	struct ropkg_file_info f_cur_file;
+	bool r_eof;
+};
+
+#endif