/*
 * 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   */

#include "lint.h"
#include "file64.h"
#include "mtlib.h"
#include <stdio.h>
#include <stddef.h>
#include <values.h>
#include <memory.h>
#include <thread.h>
#include <synch.h>
#include <errno.h>
#include <sys/types.h>
#include "stdiom.h"
#include "mse.h"

size_t
fread(void *ptr, size_t size, size_t count, FILE *iop)
{
        ssize_t s;
        int c;
        char *dptr = (char *)ptr;
        rmutex_t *lk;

        FLOCKFILE(lk, iop);

        _SET_ORIENTATION_BYTE(iop);

        /* is it a readable stream */
        if (!(iop->_flag & (_IOREAD | _IORW))) {
                iop->_flag |= _IOERR;
                errno = EBADF;
                FUNLOCKFILE(lk);
                return (0);
        }

        if (iop->_flag & _IOEOF) {
                FUNLOCKFILE(lk);
                return (0);
        }

        /* These checks are here to avoid the multiply */
        if (count == 1)
                s = size;
        else if (size == 1)
                s = count;
        else
                s = size * count;

        while (s > 0) {
                if (iop->_cnt < s) {
                        if (iop->_cnt > 0) {
                                (void) memcpy((void*)dptr, iop->_ptr,
                                    iop->_cnt);
                                dptr += iop->_cnt;
                                s -= iop->_cnt;
                        }
                        /*
                         * filbuf clobbers _cnt & _ptr,
                         * so don't waste time setting them.
                         */
                        if ((c = __filbuf(iop)) == EOF)
                                break;
                        *dptr++ = (char)c;
                        s--;
                }
                if (iop->_cnt >= s) {
                        char *tmp = (char *)iop->_ptr;
                        switch (s) {
                        case 8:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 7:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 6:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 5:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 4:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 3:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 2:
                                *dptr++ = *tmp++;
                                /*FALLTHRU*/
                        case 1:
                                *dptr++ = *tmp++;
                                break;
                        default:
                                (void) memcpy((void*)dptr, iop->_ptr,
                                    (size_t)s);
                        }
                        iop->_ptr += s;
                        iop->_cnt -= s;
                        FUNLOCKFILE(lk);
                        return (count);
                }
        }
        FUNLOCKFILE(lk);
        return (size != 0 ? count - ((s + size - 1) / size) : 0);
}