io.h

/*
Copyright (c) 2009 Yahoo! Inc.  All rights reserved.  The copyrights
embodied in the content of this file are licensed under the BSD
(revised) open source license
 */

#ifndef IO_H__
#define IO_H__

#include <fcntl.h>
#include "v_array.h"
#include<iostream>

#ifndef O_LARGEFILE //for OSX
#define O_LARGEFILE 0
#endif

class io_buf {
 public:
  v_array<char> space; //space.begin = beginning of loaded values.  space.end = end of read or written values.
  v_array<int> files;
  size_t count; // maximum number of file descriptors.
  size_t current; //file descriptor currently being used.
  char* endloaded; //end of loaded values
  v_array<char> currentname;
  v_array<char> finalname;
  
  static const int READ = 1;
  static const int WRITE = 2;

  void init(){
    size_t s = 1 << 16;
    reserve(space, s);
    current = 0;
    count = 0;
    endloaded = space.begin;
  }

  virtual int open_file(const char* name, int flag=READ){
    int ret;
    switch(flag){
    case READ:
      ret = open(name, O_RDONLY|O_LARGEFILE);
      if(ret!=-1)
        push(files,ret);
      break;

    case WRITE:
      ret = open(name, O_CREAT|O_WRONLY|O_LARGEFILE|O_TRUNC,0666);
      if(ret!=-1)
        push(files,ret);
      break;

    default:
      std::cerr << "Unknown file operation. Something other than READ/WRITE specified" << std::endl;
      ret = -1;
    }
    return ret;
  }

  virtual void reset_file(int f){
    lseek(f, 0, SEEK_SET);
    endloaded = space.begin;
    space.end = space.begin;
  }

  io_buf() {
    init();
  }

  virtual ~io_buf(){
    free(files.begin);
    free(space.begin);
  }

  void set(char *p){space.end = p;}

  virtual ssize_t read_file(int f, void* buf, size_t nbytes){
    return read(f, buf, nbytes);
  }

  size_t fill(int f) {
    if (space.end_array - endloaded == 0)
      {
	size_t offset = endloaded - space.begin;
	reserve(space, 2 * (space.end_array - space.begin));
	endloaded = space.begin+offset;
      }
    ssize_t num_read = read_file(f, endloaded, space.end_array - endloaded);
    if (num_read >= 0)
      {
	endloaded = endloaded+num_read;
	return num_read;
      }
    else
      return 0;
  }

  virtual ssize_t write_file(int f, const void* buf, size_t nbytes){
    return write(f, buf, nbytes);
  }

  virtual void flush() {
    if (write_file(files[0], space.begin, space.index()) != (int) space.index())
      std::cerr << "error, failed to write example\n";
    space.end = space.begin; fsync(files[0]); }

  virtual bool close_file(){
    if(files.index()>0){
      close(files.pop());
      return true;
    }
    return false;
  }

  void close_files(){
    while(close_file());
  }
};

void buf_write(io_buf &o, char* &pointer, int n);
unsigned int buf_read(io_buf &i, char* &pointer, int n);
size_t readto(io_buf &i, char* &pointer, char terminal);
#endif