usr/src/lib/libc/stdio/fdopen.c

/* @(#)fdopen.c 4.2 (Berkeley) 3/9/81 */
/*
 * Unix routine to do an "fopen" on file descriptor
 * The mode has to be repeated because you can't query its
 * status
 */

#include        <stdio.h>
#include        <errno.h>

FILE *
fdopen(fd, mode)
register char *mode;
{
        extern int errno;
        register FILE *iop;
        extern FILE *_lastbuf;

        for (iop = _iob; iop->_flag&(_IOREAD|_IOWRT|_IORW); iop++)
                if (iop >= _lastbuf)
                        return(NULL);
        iop->_cnt = 0;
        iop->_file = fd;
        if (*mode != 'r') {
                iop->_flag |= _IOWRT;
                if (*mode == 'a')
                        lseek(fd, 0L, 2);
        } else
                iop->_flag |= _IOREAD;
        if (mode[1] == '+') {
                iop->_flag &= ~(_IOREAD|_IOWRT);
                iop->_flag |= _IORW;
        }
        return(iop);
}