BSD 3 development

[unix-history] / usr / src / lib / libNS / fseek.c

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

/*
* Seek for standard library.  Coordinates with buffering.
*/

long fseek(iop, offset, ptrname)
register FILE *iop;
long offset;
{
       register n, resync;

       if (iop->_flag&_IODIRT) {
               fflush(iop);
               return(lseek(fileno(iop), offset, ptrname));
       }
       if (iop->_flag&(_IOREAD|_IOWRT)) {
               resync = 0;
               if (ptrname==1) {       /* relative */
                       n = iop->_cnt;
                       if (n<0)
                               n = 0;
               } else {
                       n = offset&01;
                       resync = n;
               }
               n = lseek(fileno(iop), offset - n, ptrname);
               iop->_cnt = 0;
               iop->_ptr = iop->_base ;
               iop->_delta = 0;
               if (resync)
                       getc(iop);
               return(n);
       }
       _error("fseek\n");
}

/*  The current character is always iop->_cnt characters behind the current 
position in the file, except when a file is open and in use for pure writing
in which case it is _IODIRT(y), and will be correctly positioned by fflush */