port/stdio/_filbuf.c

/*
 * 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 ident   "%Z%%M% %I% %E% SMI"


#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) {
        if ((endbuf = _findbuf(iop)) == 0) /* get buffer and */
                        /* end_of_buffer */
            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 = read(GET_FD(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);
}