/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

#pragma weak __filbuf = _filbuf

#include "lint.h"
#include "file64.h"
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include "stdiom.h"


static int
_xpg4_check(void)
{
        extern int      __xpg4;

        return (__xpg4);
}

/* fill buffer, return first character or EOF */
int
_filbuf(FILE *iop)
{
        ssize_t res;
        size_t nbyte;
        Uchar *endbuf;
#ifdef  _LP64
        unsigned int    flag;
#else
        unsigned char   flag;
#endif

        if (!(iop->_flag & _IOREAD)) {  /* check, correct permissions */
                if (iop->_flag & _IORW) {
                        iop->_flag |= _IOREAD;  /* change direction */
                                                /* to read - fseek */
                } else {
                        errno = EBADF;
                        return (EOF);
                }
        }

        if (iop->_base == 0) {
                /* Get the buffer and end of buffer */
                if ((endbuf = _findbuf(iop)) == 0) {
                        return (EOF);
                }
        } else {
                endbuf = _bufend(iop);
        }

        /*
         * Flush all line-buffered streams before we
         * read no-buffered or line-buffered input.
         */
        if (iop->_flag & (_IONBF | _IOLBF))
                _flushlbf();
        /*
         * Changed the get family fns in Solaris 10 to comply with the
         * 1990 C Standard and standards based upon it.  If the
         * end-of-file indicator for the stream is set, or if the stream
         * is at end-of-file, the function will return EOF, and the file
         * position indicator for the stream will not be advanced.
         * Additional bytes appended to the file do not clear the EOF
         * indicator.
         */
        if ((flag = iop->_flag) & _IOEOF) {
                if (_xpg4_check()) {
                        /*
                         * A previous read() has returned 0 (below),
                         * therefore iop->_cnt was set to 0, and the EOF
                         * indicator was set before returning EOF.  Reset
                         * iop->_cnt to 0; it has likely been changed by
                         * a function such as getc().
                         */
                        iop->_cnt = 0;
                        return (EOF);
                }
        }

        /*
         * Fill buffer or read 1 byte for unbuffered, handling any errors.
         */
        iop->_ptr = iop->_base;
        if (flag & _IONBF)
                nbyte = 1;
        else
                nbyte = endbuf - iop->_base;
        if ((res = _xread(iop, (char *)iop->_base, nbyte)) > 0) {
                iop->_cnt = res - 1;
                return (*iop->_ptr++);
        }

        iop->_cnt = 0;
        if (res == 0)
                iop->_flag |= _IOEOF;
        else if (!cancel_active())
                iop->_flag |= _IOERR;
        return (EOF);
}