#ifndef FILEWRAPPER_HPP
#define FILEWRAPPER_HPP

/* Part of Underdog. https://underdog.sourceforge.net
 * Released under GPLv3. Other licenses may be available.
 * Robert White © Copyright 2014 <rwhite@pobox.com>
 */


#include <string>
#include <exception>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>


struct FileWrapper {
  struct BadFile: public std::exception { };
  
  FileWrapper(std::string name, int flags, int base = AT_FDCWD):
    FileDescriptor(openat(base,name.c_str(),flags))
  {
    if (FileDescriptor == -1) {
      throw BadFile();
    }
  }

  explicit
  FileWrapper(const FileWrapper & X):
    FileDescriptor(dup(X.FileDescriptor))
  {
    if (FileDescriptor == -1) {
      throw BadFile();
    }
  }
  
  explicit
  FileWrapper(int other_fd):
    FileDescriptor(dup(other_fd))
  {
    if (FileDescriptor == -1) {
      throw BadFile();
    }
  }
  
  FileWrapper(int other_fd, int new_fd):
    FileDescriptor(dup2(other_fd,new_fd))
  {
    if (FileDescriptor == -1) {
      throw BadFile();
    }
  }
  
  void
  Replace(const FileWrapper & X)
  {
    int newfd = dup(X.FileDescriptor);
    if (newfd != -1) {
      close(FileDescriptor);
      FileDescriptor = newfd;
    }
  }
  
  ~FileWrapper()
  {
    close(FileDescriptor);
  }
  
  operator int() const { return FileDescriptor; }
  int fd() const { return FileDescriptor; }
  
protected:
  int FileDescriptor;

private:
  FileWrapper & operator =(const FileWrapper & X);
};

#endif