#include <fcntl.h>
#include "file.h"
#define PERMS 0666

FILE _iob[OPEN_MAX] = {
     { 0, (char *) 0, (char *) 0, _READ, 0},
     { 0, (char *) 0, (char *) 0, _WRITE, 1},
     { 0, (char *) 0, (char *) 0, _WRITE | _UNBUF, 2}
};

int _fillbuf(FILE *fp) {
     int bufsize;

     if ((fp->flag&(_READ|_EOF|_ERR)) != _READ)
	  return EOF;
     bufsize = (fp->flag & _UNBUF) ? 1 : BUFSIZ;
     if (fp->base == NULL)
	  if ((fp->base = (char *) malloc(bufsize)) == NULL)
	       return EOF;
     fp->ptr = fp->base;
     fp->cnt = read(fp->fd, fp->ptr, bufsize);
     if (--fp->cnt < 0) {
	  if (fp->cnt == -1)
	       fp->flag |= _EOF;
	  else
	       fp->flag != _ERR;
	  fp->cnt = 0;
	  return EOF;
     }
     return (unsigned char) *fp->ptr++;
}

FILE *fopen(char *name, char *mode) {
     int fd;
     FILE *fp;

     if (*mode != 'r' && *mode != 'w' && *mode != 'a')
	  return NULL;
     for (fp = _iob; fp < _iob + OPEN_MAX; fp++)
	  if ((fp->flag & (_READ + _WRITE)) == 0)
	       break;
     if (fp >= _iob + OPEN_MAX)
	  return NULL;

     if (*mode == 'w')
	  fd = creat(name, PERMS);
     else if (*mode == 'a') {
	  if ((fd = open(name, O_WRONLY, 0)) == -1)
	       fd = creat(name, PERMS);
	  lseek(fd, 0L, 2);
     } else
	  fd = open(name, O_RDONLY, 0);
     if (fd == -1)
	  return NULL;
     fp->fd = fd;
     fp->cnt = 0;
     fp->base = NULL;
     fp->flag = (*mode == 'r') ? _READ : _WRITE;
     return fp;
}