muduo之GzipFile

        GzipFile封装了gzip的一些API，记录一下

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)

#pragma once

#include "muduo/base/StringPiece.h"
#include "muduo/base/noncopyable.h"
#include <zlib.h>

namespace muduo
{

class GzipFile : noncopyable
{
 public:
  GzipFile(GzipFile&& rhs) noexcept
    : file_(rhs.file_)
  {
    rhs.file_ = NULL;
  }

  ~GzipFile()
  {
    if (file_)
    {
      ::gzclose(file_);
    }
  }

  GzipFile& operator=(GzipFile&& rhs) noexcept
  {
    swap(rhs);
    return *this;
  }

  bool valid() const { return file_ != NULL; }
  void swap(GzipFile& rhs) { std::swap(file_, rhs.file_); }
#if ZLIB_VERNUM >= 0x1240
  bool setBuffer(int size) { return ::gzbuffer(file_, size) == 0; }
#endif

  // return the number of uncompressed bytes actually read, 0 for eof, -1 for error
  int read(void* buf, int len) { return ::gzread(file_, buf, len); }

  // return the number of uncompressed bytes actually written
  int write(StringPiece buf) { return ::gzwrite(file_, buf.data(), buf.size()); }

  // number of uncompressed bytes
  off_t tell() const { return ::gztell(file_); }

#if ZLIB_VERNUM >= 0x1240
  // number of compressed bytes
  off_t offset() const { return ::gzoffset(file_); }
#endif

  // int flush(int f) { return ::gzflush(file_, f); }

  static GzipFile openForRead(StringArg filename)
  {
    return GzipFile(::gzopen(filename.c_str(), "rbe"));
  }

  static GzipFile openForAppend(StringArg filename)
  {
    return GzipFile(::gzopen(filename.c_str(), "abe"));
  }

  static GzipFile openForWriteExclusive(StringArg filename)
  {
    return GzipFile(::gzopen(filename.c_str(), "wbxe"));
  }

  static GzipFile openForWriteTruncate(StringArg filename)
  {
    return GzipFile(::gzopen(filename.c_str(), "wbe"));
  }

 private:
  explicit GzipFile(gzFile file)
    : file_(file)
  {
  }

  gzFile file_;
};

}  // namespace muduo