/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/sysctl.h>

#include <errno.h>
#include <limits.h>
#include <paths.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

extern int __sysctl(const int *name, u_int namelen, void *oldp,
    size_t *oldlenp, const void *newp, size_t newlen);

static int
set_user_str(void *dstp, size_t *dstlenp, const char *src, size_t len,
    size_t maxlen)
{
        int retval;

        retval = 0;
        if (dstp != NULL) {
                if (len > maxlen) {
                        len = maxlen;
                        errno = ENOMEM;
                        retval = -1;
                }
                memcpy(dstp, src, len);
        }
        *dstlenp = len;
        return (retval);
}

int
sysctl(const int *name, u_int namelen, void *oldp, size_t *oldlenp,
    const void *newp, size_t newlen)
{
        int retval;
        size_t orig_oldlen;

        orig_oldlen = oldlenp != NULL ? *oldlenp : 0;
        retval = __sysctl(name, namelen, oldp, oldlenp, newp, newlen);
        /*
         * Valid names under CTL_USER except USER_LOCALBASE have a dummy entry
         * in the sysctl tree (to support name lookups and enumerations) with
         * an empty/zero value, and the true value is supplied by this routine.
         * For all such names, __sysctl() is used solely to validate the name.
         *
         * Return here unless there was a successful lookup for a CTL_USER name.
         */
        if (retval != 0 || name[0] != CTL_USER)
                return (retval);

        if (namelen != 2) {
                errno = EINVAL;
                return (-1);
        }

        /* Variables under CLT_USER that may be overridden by kernel values */
        switch (name[1]) {
        case USER_LOCALBASE:
                if (oldlenp == NULL || *oldlenp > sizeof(""))
                        return (0);
                return (set_user_str(oldp, oldlenp, _PATH_LOCALBASE,
                        sizeof(_PATH_LOCALBASE), orig_oldlen));
        }

        /* Variables under CLT_USER whose values are immutably defined below */
        if (newp != NULL) {
                errno = EPERM;
                return (-1);
        }

        switch (name[1]) {
        case USER_CS_PATH:
                return (set_user_str(oldp, oldlenp, _PATH_STDPATH,
                    sizeof(_PATH_STDPATH), orig_oldlen));
        }

        if (oldp != NULL && *oldlenp < sizeof(int)) {
                errno = ENOMEM;
                return (-1);
        }
        *oldlenp = sizeof(int);
        if (oldp == NULL)
                return (0);

        switch (name[1]) {
        case USER_BC_BASE_MAX:
                *(int *)oldp = BC_BASE_MAX;
                return (0);
        case USER_BC_DIM_MAX:
                *(int *)oldp = BC_DIM_MAX;
                return (0);
        case USER_BC_SCALE_MAX:
                *(int *)oldp = BC_SCALE_MAX;
                return (0);
        case USER_BC_STRING_MAX:
                *(int *)oldp = BC_STRING_MAX;
                return (0);
        case USER_COLL_WEIGHTS_MAX:
                *(int *)oldp = COLL_WEIGHTS_MAX;
                return (0);
        case USER_EXPR_NEST_MAX:
                *(int *)oldp = EXPR_NEST_MAX;
                return (0);
        case USER_LINE_MAX:
                *(int *)oldp = LINE_MAX;
                return (0);
        case USER_RE_DUP_MAX:
                *(int *)oldp = RE_DUP_MAX;
                return (0);
        case USER_POSIX2_VERSION:
                *(int *)oldp = _POSIX2_VERSION;
                return (0);
        case USER_POSIX2_C_BIND:
#ifdef POSIX2_C_BIND
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_C_DEV:
#ifdef  POSIX2_C_DEV
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_CHAR_TERM:
#ifdef  POSIX2_CHAR_TERM
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_FORT_DEV:
#ifdef  POSIX2_FORT_DEV
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_FORT_RUN:
#ifdef  POSIX2_FORT_RUN
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_LOCALEDEF:
#ifdef  POSIX2_LOCALEDEF
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_SW_DEV:
#ifdef  POSIX2_SW_DEV
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_POSIX2_UPE:
#ifdef  POSIX2_UPE
                *(int *)oldp = 1;
#else
                *(int *)oldp = 0;
#endif
                return (0);
        case USER_STREAM_MAX:
                *(int *)oldp = FOPEN_MAX;
                return (0);
        case USER_TZNAME_MAX:
                *(int *)oldp = NAME_MAX;
                return (0);
        default:
                errno = EINVAL;
                return (-1);
        }
        /* NOTREACHED */
}