Introduce IOFile abstract class to refactor BufferedFile and GZipFile

IOFile provides the same interface of old BufferedFile. It provides
extension points as pure virtual functions. Those functions are
implemented by 2 concrete subclasses: BufferedFile and GZipFile.

src/IOFile.h

@@ -0,0 +1,103 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2011 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef D_IO_FILE_H
+#define D_IO_FILE_H
+
+#include "OutputFile.h"
+
+#include <string>
+#include <iosfwd>
+
+namespace aria2 {
+
+// This is a wrapper base class intended to provide
+// fopen/fclose/fread/fwrite/fgets functionality.
+class IOFile:public OutputFile {
+private:
+  typedef void (IOFile::*unspecified_bool_type)() const;
+  void goodState() const {}
+public:
+  IOFile() {}
+  virtual ~IOFile() {}
+  // Returns true if file is opened and ferror returns 0. Otherwise
+  // returns false.
+  operator unspecified_bool_type() const;
+  // wrapper for fread. Using 1 for 2nd argument of fread.
+  size_t read(void* ptr, size_t count);
+  // wrapper for fwrite. Using 1 for 2nd argument of fwrite.
+  size_t write(const void* ptr, size_t count);
+  virtual size_t write(const char* str);
+  // wrapper for fgets
+  char* gets(char* s, int size);
+  // wrapper for fgets, but trailing '\n' is replaced with '\0'.
+  char* getsn(char* s, int size);
+  // Reads one line and returns it. The last '\n' is removed.
+  std::string getLine();
+  // wrapper for fclose
+  int close();
+  // wrapper for fflush
+  int flush();
+  // Return true if file is opened && feof(fp_) != 0. Otherwise
+  // returns false.
+  bool eof();
+  // Returns true if file supports ANSI color escape codes.
+  bool supportsColor();
+  // Convenient method. Read data to end of file and write them into
+  // given stream. Returns written size.
+  size_t transfer(std::ostream& out);
+  int vprintf(const char* format, va_list va);
+  // Mode for reading
+  static const char READ[];
+  // Mode for writing
+  static const char WRITE[];
+  // Mode for append
+  static const char APPEND[];
+protected:
+  virtual size_t onRead(void* ptr, size_t count) = 0;
+  virtual size_t onWrite(const void* ptr, size_t count) = 0;
+  virtual char* onGets(char* s, int size) = 0;
+  virtual int onVprintf(const char* format, va_list va) = 0;
+  virtual int onFlush() = 0;
+  virtual int onClose() = 0;
+  virtual bool onSupportsColor() = 0;
+
+  virtual bool isError() const = 0;
+  virtual bool isEOF() const = 0;
+  virtual bool isOpen() const = 0;
+};
+
+} // namespace aria2
+
+#endif // D_IO_FILE_H