BSD 3 development

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

/* Copyright (c) 1979 Regents of the University of California */
#include        <stdio.h>
_filbuf(iop)
register struct _iobuf *iop;
{
       static char smallbuf[_NFILE];
       register n;
       char *malloc();

       if ((iop->_flag&_IOREAD) == 0)
               _error("Reading bad file\n");
       if (iop->_flag&_IOSTRG)
               return(-1);
tryagain:
       if (iop->_base==NULL) {
               if (iop->_flag&_IONBF) {
                       iop->_base = &smallbuf[fileno(iop)];
                       goto tryagain;
               }
               if ((iop->_base = malloc(BUFSIZ)) == NULL) {
                       iop->_flag |= _IONBF;
                       goto tryagain;
               }
               iop->_flag |= _IOMYBUF;
       }
       if((iop->_flag & _IODIRT) && !(iop->_flag & _IONBF) && (iop->_flag & _IOWRT)) {
               if (iop->_delta)
                       if (lseek(iop->_file,(long)  -iop->_delta, 1) < 0) {
                               _error("Seek error in filbuf\n");
                               iop->_flag |= _IOERR;
                       }
               if( 0 < (n = iop->_ptr - iop->_base))
                       if( n != write(iop->_file, iop->_base, n) )
                               iop->_flag |= _IOERR;
               iop->_flag &= ~_IODIRT;
       }
       iop->_ptr = iop->_base;
       iop->_cnt = read(fileno(iop), iop->_ptr, iop->_flag&_IONBF?1:BUFSIZ);
       iop->_delta = iop->_cnt;
       if (--iop->_cnt < 0) {
               if (iop->_cnt == -1)
                       iop->_flag |= _IOEOF;
               else
                       iop->_flag |= _IOERR;
               iop->_cnt = 0;
               return(-1);
       }
       return(*iop->_ptr++&0377);
}