BSD 2 development

[unix-history] / src / libNS / freopen.c

/* Copyright (c) 1979 Regents of the University of California */
#include        <stdio.h>

struct _iobuf *freopen(file, mode, iop)
register char *mode;
register struct _iobuf *iop;
{
       register f;
       int unixmode, a_flag;

       fclose(iop);
       a_flag = 0;
       for(;*mode;mode++) {
               switch(*mode) {

               case 'w':
                       iop->_flag |= _IOWRT;
                       break;

               case 'r':
                       iop->_flag |= _IOREAD;
                       break;

               case 'a':
                       a_flag = 1;
                       iop->_flag |= _IOWRT ;
               }
       }
       if((unixmode = (iop->_flag & 3) - 1) < 0) {
               unixmode = 0;
               iop->_flag = 1;
       }
       if ((iop->_flag & _IOWRT) && a_flag==0 ) {
               f = creat(file, 0644);
               if((iop->_flag & _IOREAD) && (f > 0)) {
                       close(f);
                       f = open(file,2);
               }
       } else if ((0>(f = open(file, unixmode))) && (a_flag || !(iop->_flag&_IOREAD))){
                       f = creat(file, 0644);
                       close(f);
                       f = open(file,unixmode);
               }

       if (f < 0)
               return(NULL);
       if (a_flag)
               lseek(f, (long) 0, 2);
       iop->_file = f;
       return(iop);
}