ia32/os/copy_subr.c

	copy_subr.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Miscellaneous C routines for copying data around without
 * descending into assembler.  Compilers are pretty good at
 * scheduling instructions, and humans are pretty hopeless at
 * writing correct assembler.
 */

#include <sys/types.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/param.h>

/*
 * copyinstr_noerr and copyoutstr_noerr can be implemented completely
 * in C on machines with shared user and kernel context.
 */
static int
copystr_nofault(const char *src, char *dst, size_t maxlength,
    size_t *lencopied)
{
    int error = 0;
    size_t leftover;

    if ((leftover = maxlength) == 0)
        error = ENAMETOOLONG;
    else
        do {
            leftover--;
            if ((*dst++ = *src++) == '\0')
                break;
            if (leftover == 0) {
                error = ENAMETOOLONG;
                break;
            }
        /*CONSTCOND*/
        } while (1);

    if (lencopied)
        *lencopied = maxlength - leftover;
    return (error);
}


int
copyinstr_noerr(const char *uaddr, char *kaddr, size_t maxlength,
    size_t *lencopied)
{
    char *ua = (char *)uaddr;

    ASSERT((uintptr_t)kaddr > kernelbase);

    if ((uintptr_t)ua > kernelbase) {
        /*
         * force fault at kernelbase
         */
        ua = (char *)kernelbase;
    }
    return (copystr_nofault(ua, kaddr, maxlength, lencopied));
}

int
copyoutstr_noerr(const char *kaddr, char *uaddr, size_t maxlength,
    size_t *lencopied)
{
    char *ua = (char *)uaddr;

    ASSERT((uintptr_t)kaddr > kernelbase);

    if ((uintptr_t)ua > kernelbase) {
        /*
         * force fault at kernelbase
         */
        ua = (char *)kernelbase;
    }
    return (copystr_nofault(kaddr, ua, maxlength, lencopied));
}