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

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fdopen.c    5.2 (Berkeley) 3/9/86";
#endif LIBC_SCCS and not lint

/*
 * Unix routine to do an "fopen" on file descriptor
 * The mode has to be repeated because you can't query its
 * status
 */

#include <sys/types.h>
#include <sys/file.h>
#include <stdio.h>

FILE *
fdopen(fd, mode)
        register char *mode;
{
        extern FILE *_findiop();
        static int nofile = -1;
        register FILE *iop;

        if (nofile < 0)
                nofile = getdtablesize();

        if (fd < 0 || fd >= nofile)
                return (NULL);

        iop = _findiop();
        if (iop == NULL)
                return (NULL);

        iop->_cnt = 0;
        iop->_file = fd;
        iop->_bufsiz = 0;
        iop->_base = iop->_ptr = NULL;

        switch (*mode) {
        case 'r':
                iop->_flag = _IOREAD;
                break;
        case 'a':
                lseek(fd, (off_t)0, L_XTND);
                /* fall into ... */
        case 'w':
                iop->_flag = _IOWRT;
                break;
        default:
                return (NULL);
        }

        if (mode[1] == '+')
                iop->_flag = _IORW;

        return (iop);
}