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[unix-history] / usr / src / lib / libc / stdio / ftell.c

#ifndef lint
static char sccsid[] = "@(#)ftell.c     5.1 (Berkeley) %G%";
#endif not lint

/*
* Return file offset.
* Coordinates with buffering.
*/

#include        <stdio.h>
long    lseek();


long ftell(iop)
register FILE *iop;
{
       register long tres;
       register adjust;

       if (iop->_cnt < 0)
               iop->_cnt = 0;
       if (iop->_flag&_IOREAD)
               adjust = - iop->_cnt;
       else if (iop->_flag&(_IOWRT|_IORW)) {
               adjust = 0;
               if (iop->_flag&_IOWRT && iop->_base && (iop->_flag&_IONBF)==0)
                       adjust = iop->_ptr - iop->_base;
       } else
               return(-1);
       tres = lseek(fileno(iop), 0L, 1);
       if (tres<0)
               return(tres);
       tres += adjust;
       return(tres);
}