[apple/xnu.git] / bsd / kern / kern_newsysctl.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code 
 * as defined in and that are subject to the Apple Public Source License 
 * Version 2.0 (the 'License'). You may not use this file except in 
 * compliance with the License.  The rights granted to you under the 
 * License may not be used to create, or enable the creation or 
 * redistribution of, unlawful or unlicensed copies of an Apple operating 
 * system, or to circumvent, violate, or enable the circumvention or 
 * violation of, any terms of an Apple operating system software license 
 * agreement.
 *
 * Please obtain a copy of the License at 
 * http://www.opensource.apple.com/apsl/ and read it before using this 
 * file.
 *
 * The Original Code and all software distributed under the License are 
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
 * Please see the License for the specific language governing rights and 
 * limitations under the License.
 *
 * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
 */
/*-
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Karels at Berkeley Software Design, Inc.
 *
 * Quite extensively rewritten by Poul-Henning Kamp of the FreeBSD
 * project, to make these variables more userfriendly.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      @(#)kern_sysctl.c       8.4 (Berkeley) 4/14/94
 */


#include <sys/param.h>
#include <sys/buf.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/proc_internal.h>
#include <sys/systm.h>

#include <bsm/audit_kernel.h>

/*
struct sysctl_oid_list sysctl__debug_children;
struct sysctl_oid_list sysctl__kern_children;
struct sysctl_oid_list sysctl__net_children;
struct sysctl_oid_list sysctl__sysctl_children;
*/

extern struct sysctl_oid *newsysctl_list[];
extern struct sysctl_oid *machdep_sysctl_list[];


static void
sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i);



/*
 * Locking and stats
 */
static struct sysctl_lock {
        int     sl_lock;
        int     sl_want;
        int     sl_locked;
} memlock;

/*
 * XXX this does not belong here
 */
static funnel_t *
spl_kernel_funnel(void)
{
        funnel_t *cfunnel;

        cfunnel = thread_funnel_get();
        if (cfunnel != kernel_flock) {
                if (cfunnel != NULL)
                        thread_funnel_set(cfunnel, FALSE);
                thread_funnel_set(kernel_flock, TRUE);
        }
        return(cfunnel);
}

static void
splx_kernel_funnel(funnel_t *saved)
{
        if (saved != kernel_flock) {
                thread_funnel_set(kernel_flock, FALSE);
                if (saved != NULL) 
                        thread_funnel_set(saved, TRUE);
        }
}

static int sysctl_root SYSCTL_HANDLER_ARGS;

struct sysctl_oid_list sysctl__children; /* root list */

/*
 * Initialization of the MIB tree.
 *
 * Order by number in each list.
 */

void sysctl_register_oid(struct sysctl_oid *oidp)
{
        struct sysctl_oid_list *parent = oidp->oid_parent;
        struct sysctl_oid *p;
        struct sysctl_oid *q;
        int n;
        funnel_t *fnl;

        fnl = spl_kernel_funnel();

        /*
         * If this oid has a number OID_AUTO, give it a number which
         * is greater than any current oid.  Make sure it is at least
         * 100 to leave space for pre-assigned oid numbers.
         */
/*      sysctl_sysctl_debug_dump_node(parent, 3); */
        if (oidp->oid_number == OID_AUTO) {
                /* First, find the highest oid in the parent list >99 */
                n = 99;
                SLIST_FOREACH(p, parent, oid_link) {
                        if (p->oid_number > n)
                                n = p->oid_number;
                }
                oidp->oid_number = n + 1;
        }

        /*
         * Insert the oid into the parent's list in order.
         */
        q = NULL;
        SLIST_FOREACH(p, parent, oid_link) {
                if (oidp->oid_number < p->oid_number)
                        break;
                q = p;
        }
        if (q)
                SLIST_INSERT_AFTER(q, oidp, oid_link);
        else
                SLIST_INSERT_HEAD(parent, oidp, oid_link);

        splx_kernel_funnel(fnl);
}

void sysctl_unregister_oid(struct sysctl_oid *oidp)
{
        funnel_t *fnl;

        fnl = spl_kernel_funnel();
        SLIST_REMOVE(oidp->oid_parent, oidp, sysctl_oid, oid_link);
        splx_kernel_funnel(fnl);
}

/*
 * Bulk-register all the oids in a linker_set.
 */
void sysctl_register_set(struct linker_set *lsp)
{
        int count = lsp->ls_length;
        int i;
        for (i = 0; i < count; i++)
                sysctl_register_oid((struct sysctl_oid *) lsp->ls_items[i]);
}

void sysctl_unregister_set(struct linker_set *lsp)
{
        int count = lsp->ls_length;
        int i;
        for (i = 0; i < count; i++)
                sysctl_unregister_oid((struct sysctl_oid *) lsp->ls_items[i]);
}


/*
 * Register OID's from fixed list
 */

void sysctl_register_fixed()
{
    int i;

    for (i=0; newsysctl_list[i]; i++) {
        sysctl_register_oid(newsysctl_list[i]);
    }
    for (i=0; machdep_sysctl_list[i]; i++) {
        sysctl_register_oid(machdep_sysctl_list[i]);
    }
}

/*
 * Register the kernel's oids on startup.
 */
struct linker_set sysctl_set;

void sysctl_register_all(void *arg)
{
        sysctl_register_set(&sysctl_set);
}

SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);

/*
 * "Staff-functions"
 *
 * These functions implement a presently undocumented interface 
 * used by the sysctl program to walk the tree, and get the type
 * so it can print the value.
 * This interface is under work and consideration, and should probably
 * be killed with a big axe by the first person who can find the time.
 * (be aware though, that the proper interface isn't as obvious as it
 * may seem, there are various conflicting requirements.
 *
 * {0,0}        printf the entire MIB-tree.
 * {0,1,...}    return the name of the "..." OID.
 * {0,2,...}    return the next OID.
 * {0,3}        return the OID of the name in "new"
 * {0,4,...}    return the kind & format info for the "..." OID.
 */

static void
sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
{
        int k;
        struct sysctl_oid *oidp;

        SLIST_FOREACH(oidp, l, oid_link) {

                for (k=0; k<i; k++)
                        printf(" ");

                printf("%d %s ", oidp->oid_number, oidp->oid_name);

                printf("%c%c",
                        oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
                        oidp->oid_kind & CTLFLAG_WR ? 'W':' ');

                if (oidp->oid_handler)
                        printf(" *Handler");

                switch (oidp->oid_kind & CTLTYPE) {
                        case CTLTYPE_NODE:
                                printf(" Node\n");
                                if (!oidp->oid_handler) {
                                        sysctl_sysctl_debug_dump_node(
                                                oidp->oid_arg1, i+2);
                                }
                                break;
                        case CTLTYPE_INT:    printf(" Int\n"); break;
                        case CTLTYPE_STRING: printf(" String\n"); break;
                        case CTLTYPE_QUAD:   printf(" Quad\n"); break;
                        case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
                        default:             printf("\n");
                }

        }
}

static int
sysctl_sysctl_debug SYSCTL_HANDLER_ARGS
{
        sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
        return ENOENT;
}

SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD,
        0, 0, sysctl_sysctl_debug, "-", "");

static int
sysctl_sysctl_name SYSCTL_HANDLER_ARGS
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int error = 0;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
        char tempbuf[10];

        while (namelen) {
                if (!lsp) {
                        snprintf(tempbuf,sizeof(tempbuf),"%d",*name);
                        if (req->oldidx)
                                error = SYSCTL_OUT(req, ".", 1);
                        if (!error)
                                error = SYSCTL_OUT(req, tempbuf, strlen(tempbuf));
                        if (error)
                                return (error);
                        namelen--;
                        name++;
                        continue;
                }
                lsp2 = 0;
                SLIST_FOREACH(oid, lsp, oid_link) {
                        if (oid->oid_number != *name)
                                continue;

                        if (req->oldidx)
                                error = SYSCTL_OUT(req, ".", 1);
                        if (!error)
                                error = SYSCTL_OUT(req, oid->oid_name,
                                        strlen(oid->oid_name));
                        if (error)
                                return (error);

                        namelen--;
                        name++;

                        if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
                                break;

                        if (oid->oid_handler)
                                break;

                        lsp2 = (struct sysctl_oid_list *)oid->oid_arg1;
                        break;
                }
                lsp = lsp2;
        }
        return (SYSCTL_OUT(req, "", 1));
}

SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD, sysctl_sysctl_name, "");

static int
sysctl_sysctl_next_ls (struct sysctl_oid_list *lsp, int *name, u_int namelen, 
        int *next, int *len, int level, struct sysctl_oid **oidpp)
{
        struct sysctl_oid *oidp;

        *len = level;
        SLIST_FOREACH(oidp, lsp, oid_link) {
                *next = oidp->oid_number;
                *oidpp = oidp;

                if (!namelen) {
                        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
                                return 0;
                        if (oidp->oid_handler) 
                                /* We really should call the handler here...*/
                                return 0;
                        lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                        if (!sysctl_sysctl_next_ls (lsp, 0, 0, next+1, 
                                len, level+1, oidpp))
                                return 0;
                        goto next;
                }

                if (oidp->oid_number < *name)
                        continue;

                if (oidp->oid_number > *name) {
                        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                                return 0;
                        if (oidp->oid_handler)
                                return 0;
                        lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                        if (!sysctl_sysctl_next_ls (lsp, name+1, namelen-1, 
                                next+1, len, level+1, oidpp))
                                return (0);
                        goto next;
                }
                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                        continue;

                if (oidp->oid_handler)
                        continue;

                lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                if (!sysctl_sysctl_next_ls (lsp, name+1, namelen-1, next+1, 
                        len, level+1, oidpp))
                        return (0);
        next:
                namelen = 1;
                *len = level;
        }
        return 1;
}

static int
sysctl_sysctl_next SYSCTL_HANDLER_ARGS
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int i, j, error;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children;
        int newoid[CTL_MAXNAME];

        i = sysctl_sysctl_next_ls (lsp, name, namelen, newoid, &j, 1, &oid);
        if (i)
                return ENOENT;
        error = SYSCTL_OUT(req, newoid, j * sizeof (int));
        return (error);
}

SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD, sysctl_sysctl_next, "");

static int
name2oid (char *name, int *oid, int *len, struct sysctl_oid **oidpp)
{
        int i;
        struct sysctl_oid *oidp;
        struct sysctl_oid_list *lsp = &sysctl__children;
        char *p;

        if (!*name)
                return ENOENT;

        p = name + strlen(name) - 1 ;
        if (*p == '.')
                *p = '\0';

        *len = 0;

        for (p = name; *p && *p != '.'; p++) 
                ;
        i = *p;
        if (i == '.')
                *p = '\0';

        oidp = SLIST_FIRST(lsp);

        while (oidp && *len < CTL_MAXNAME) {
                if (strcmp(name, oidp->oid_name)) {
                        oidp = SLIST_NEXT(oidp, oid_link);
                        continue;
                }
                *oid++ = oidp->oid_number;
                (*len)++;

                if (!i) {
                        if (oidpp)
                                *oidpp = oidp;
                        return (0);
                }

                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                        break;

                if (oidp->oid_handler)
                        break;

                lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                oidp = SLIST_FIRST(lsp);
                name = p+1;
                for (p = name; *p && *p != '.'; p++) 
                                ;
                i = *p;
                if (i == '.')
                        *p = '\0';
        }
        return ENOENT;
}

static int
sysctl_sysctl_name2oid SYSCTL_HANDLER_ARGS
{
        char *p;
        int error, oid[CTL_MAXNAME], len;
        struct sysctl_oid *op = 0;

        if (!req->newlen) 
                return ENOENT;
        if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
                return (ENAMETOOLONG);

        MALLOC(p, char *,req->newlen+1, M_TEMP, M_WAITOK);
        if (!p)
            return ENOMEM;

        error = SYSCTL_IN(req, p, req->newlen);
        if (error) {
                FREE(p, M_TEMP);
                return (error);
        }

        p [req->newlen] = '\0';

        error = name2oid(p, oid, &len, &op);

        FREE(p, M_TEMP);

        if (error)
                return (error);

        error = SYSCTL_OUT(req, oid, len * sizeof *oid);
        return (error);
}

SYSCTL_PROC(_sysctl, 3, name2oid, CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_KERN, 0, 0, 
        sysctl_sysctl_name2oid, "I", "");

static int
sysctl_sysctl_oidfmt SYSCTL_HANDLER_ARGS
{
        int *name = (int *) arg1, error;
        u_int namelen = arg2;
        int indx;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children;

        oid = SLIST_FIRST(lsp);

        indx = 0;
        while (oid && indx < CTL_MAXNAME) {
                if (oid->oid_number == name[indx]) {
                        indx++;
                        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                                if (oid->oid_handler)
                                        goto found;
                                if (indx == namelen)
                                        goto found;
                                lsp = (struct sysctl_oid_list *)oid->oid_arg1;
                                oid = SLIST_FIRST(lsp);
                        } else {
                                if (indx != namelen)
                                        return EISDIR;
                                goto found;
                        }
                } else {
                        oid = SLIST_NEXT(oid, oid_link);
                }
        }
        return ENOENT;
found:
        if (!oid->oid_fmt)
                return ENOENT;
        error = SYSCTL_OUT(req, 
                &oid->oid_kind, sizeof(oid->oid_kind));
        if (!error)
                error = SYSCTL_OUT(req, oid->oid_fmt, 
                        strlen(oid->oid_fmt)+1);
        return (error);
}


SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD, sysctl_sysctl_oidfmt, "");

/*
 * Default "handler" functions.
 */

/*
 * Handle an int, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_int SYSCTL_HANDLER_ARGS
{
        int error = 0;

        if (arg1)
                error = SYSCTL_OUT(req, arg1, sizeof(int));
        else
                error = SYSCTL_OUT(req, &arg2, sizeof(int));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(int));

        if (error == 0)
                AUDIT_ARG(value, *(int *)arg1);
        return (error);
}

/*
 * Handle a long, signed or unsigned.  arg1 points to it.
 */

int
sysctl_handle_long SYSCTL_HANDLER_ARGS
{
        int error = 0;

        if (!arg1)
                return (EINVAL);
        error = SYSCTL_OUT(req, arg1, sizeof(long));

        if (error || !req->newptr)
                return (error);

        error = SYSCTL_IN(req, arg1, sizeof(long));
        return (error);
}

/*
 * Handle a quad, signed or unsigned.  arg1 points to it.
 */

int
sysctl_handle_quad SYSCTL_HANDLER_ARGS
{
        int error = 0;

        if (!arg1)
                return (EINVAL);
        error = SYSCTL_OUT(req, arg1, sizeof(long long));

        if (error || !req->newptr)
                return (error);

        error = SYSCTL_IN(req, arg1, sizeof(long long));
        return (error);
}

/*
 * Expose an int value as a quad.
 *
 * This interface allows us to support interfaces defined
 * as using quad values while the implementation is still
 * using ints.
 */
int
sysctl_handle_int2quad SYSCTL_HANDLER_ARGS
{
        int error = 0;
        long long val;
        int newval;

        if (!arg1)
                return (EINVAL);
        val = (long long)*(int *)arg1;
        error = SYSCTL_OUT(req, &val, sizeof(long long));

        if (error || !req->newptr)
                return (error);

        error = SYSCTL_IN(req, &val, sizeof(long long));
        if (!error) {
                /*
                 * Value must be representable; check by
                 * casting and then casting back.
                 */
                newval = (int)val;
                if ((long long)newval != val) {
                        error = ERANGE;
                } else {
                        *(int *)arg1 = newval;
                }
        }
        return (error);
}

/*
 * Handle our generic '\0' terminated 'C' string.
 * Two cases:
 *      a variable string:  point arg1 at it, arg2 is max length.
 *      a constant string:  point arg1 at it, arg2 is zero.
 */

int
sysctl_handle_string SYSCTL_HANDLER_ARGS
{
        int error=0;

        error = SYSCTL_OUT(req, arg1, strlen((char *)arg1)+1);

        if (error || !req->newptr)
                return (error);

        if ((req->newlen - req->newidx) >= arg2) {
                error = EINVAL;
        } else {
                arg2 = (req->newlen - req->newidx);
                error = SYSCTL_IN(req, arg1, arg2);
                ((char *)arg1)[arg2] = '\0';
        }

        return (error);
}

/*
 * Handle any kind of opaque data.
 * arg1 points to it, arg2 is the size.
 */

int
sysctl_handle_opaque SYSCTL_HANDLER_ARGS
{
        int error;

        error = SYSCTL_OUT(req, arg1, arg2);

        if (error || !req->newptr)
                return (error);

        error = SYSCTL_IN(req, arg1, arg2);

        return (error);
}

/*
 * Transfer functions to/from kernel space.
 */
static int
sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
{
        size_t i = 0;

        if (req->oldptr) {
                i = l;
                if (i > req->oldlen - req->oldidx)
                        i = req->oldlen - req->oldidx;
                if (i > 0)
                        bcopy((void*)p, CAST_DOWN(char *, (req->oldptr + req->oldidx)), i);
        }
        req->oldidx += l;
        if (req->oldptr && i != l)
                return (ENOMEM);
        return (0);
}

static int
sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
{
        if (!req->newptr)
                return 0;
        if (req->newlen - req->newidx < l)
                return (EINVAL);
        bcopy(CAST_DOWN(char *, (req->newptr + req->newidx)), p, l);
        req->newidx += l;
        return (0);
}

int
kernel_sysctl(struct proc *p, int *name, u_int namelen, void *old, size_t *oldlenp, void *new, size_t newlen)
{
        int error = 0;
        struct sysctl_req req;
        funnel_t *fnl;

        /*
         * Construct request.
         */
        bzero(&req, sizeof req);
        req.p = p;
        if (oldlenp)
                req.oldlen = *oldlenp;
        if (old)
                req.oldptr = CAST_USER_ADDR_T(old);
        if (newlen) {
                req.newlen = newlen;
                req.newptr = CAST_USER_ADDR_T(new);
        }
        req.oldfunc = sysctl_old_kernel;
        req.newfunc = sysctl_new_kernel;
        req.lock = 1;

        /*
         * Locking.  Tree traversal always begins with the kernel funnel held.
         */
        fnl = spl_kernel_funnel();

        /* XXX this should probably be done in a general way */
        while (memlock.sl_lock) {
                memlock.sl_want = 1;
                (void) tsleep((caddr_t)&memlock, PRIBIO+1, "sysctl", 0);
                memlock.sl_locked++;
        }
        memlock.sl_lock = 1;

        /* make the request */
        error = sysctl_root(0, name, namelen, &req);

        /* unlock memory if required */
        if (req.lock == 2)
                vsunlock(req.oldptr, (user_size_t)req.oldlen, B_WRITE);

        memlock.sl_lock = 0;

        if (memlock.sl_want) {
                memlock.sl_want = 0;
                wakeup((caddr_t)&memlock);
        }

        /*
         * Undo locking.
         */
        splx_kernel_funnel(fnl);

        if (error && error != ENOMEM)
                return (error);

        if (oldlenp)
                *oldlenp = req.oldidx;

        return (error);
}

/*
 * Transfer function to/from user space.
 */
static int
sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
{
        int error = 0;
        size_t i = 0;

        if (req->oldptr) {
                if (req->oldlen - req->oldidx < l)
                    return (ENOMEM);
                i = l;
                if (i > req->oldlen - req->oldidx)
                        i = req->oldlen - req->oldidx;
                if (i > 0)
                        error = copyout((void*)p, (req->oldptr + req->oldidx), i);
        }
        req->oldidx += l;
        if (error)
                return (error);
        if (req->oldptr && i < l)
                return (ENOMEM);
        return (0);
}

static int
sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
{
        int error;

        if (!req->newptr)
                return 0;
        if (req->newlen - req->newidx < l)
                return (EINVAL);
        error = copyin((req->newptr + req->newidx), p, l);
        req->newidx += l;
        return (error);
}

/*
 * Traverse our tree, and find the right node, execute whatever it points
 * at, and return the resulting error code.
 */

int
sysctl_root SYSCTL_HANDLER_ARGS
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int indx, i;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children;
        int error;

        oid = SLIST_FIRST(lsp);

        indx = 0;
        while (oid && indx < CTL_MAXNAME) {
                if (oid->oid_number == name[indx]) {
                        indx++;
                        if (oid->oid_kind & CTLFLAG_NOLOCK)
                                req->lock = 0;
                        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                                if (oid->oid_handler)
                                        goto found;
                                if (indx == namelen)
                                        return ENOENT;
                                lsp = (struct sysctl_oid_list *)oid->oid_arg1;
                                oid = SLIST_FIRST(lsp);
                        } else {
                                if (indx != namelen)
                                        return EISDIR;
                                goto found;
                        }
                } else {
                        oid = SLIST_NEXT(oid, oid_link);
                }
        }
        return ENOENT;
found:
        /* If writing isn't allowed */
        if (req->newptr && (!(oid->oid_kind & CTLFLAG_WR) ||
                            ((oid->oid_kind & CTLFLAG_SECURE) && securelevel > 0))) {
                return (EPERM);
        }

        /*
         * If we're inside the kernel, the OID must be marked as kernel-valid.
         * XXX This mechanism for testing is bad.
         */
        if ((req->oldfunc == sysctl_old_kernel) && !(oid->oid_kind & CTLFLAG_KERN))
                return(EPERM);

        /* Most likely only root can write */
        if (!(oid->oid_kind & CTLFLAG_ANYBODY) &&
            req->newptr && req->p &&
            (error = suser(req->p->p_ucred, &req->p->p_acflag)))
                return (error);

        if (!oid->oid_handler) {
            return EINVAL;
        }


        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                i = (oid->oid_handler) (oid,
                                        name + indx, namelen - indx,
                                        req);
        } else {
                i = (oid->oid_handler) (oid,
                                        oid->oid_arg1, oid->oid_arg2,
                                        req);
        }

        return (i);
}

#ifndef _SYS_SYSPROTO_H_
struct sysctl_args {
        int     *name;
        u_int   namelen;
        void    *old;
        size_t  *oldlenp;
        void    *new;
        size_t  newlen;
};
#endif

int
/* __sysctl(struct proc *p, struct sysctl_args *uap) */
new_sysctl(struct proc *p, struct sysctl_args *uap)
{
        int error, i, name[CTL_MAXNAME];
        size_t j;

        if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
                return (EINVAL);

        error = copyin(CAST_USER_ADDR_T(uap->name), &name, uap->namelen * sizeof(int));
        if (error)
                return (error);

        error = userland_sysctl(p, name, uap->namelen,
                                    CAST_USER_ADDR_T(uap->old), uap->oldlenp, 0,
                                    CAST_USER_ADDR_T(uap->new), uap->newlen, &j);
        if (error && error != ENOMEM)
                return (error);
        if (uap->oldlenp) {
                i = copyout(&j, CAST_USER_ADDR_T(uap->oldlenp), sizeof(j));
                if (i)
                        return (i);
        }
        return (error);
}

/*
 * This is used from various compatibility syscalls too.  That's why name
 * must be in kernel space.
 */
int
userland_sysctl(struct proc *p, int *name, u_int namelen, user_addr_t oldp, 
                size_t *oldlenp, int inkernel, user_addr_t newp, size_t newlen, 
                size_t *retval)
{
        int error = 0;
        struct sysctl_req req, req2;

        bzero(&req, sizeof req);

        req.p = p;

        if (oldlenp) {
                if (inkernel) {
                        req.oldlen = *oldlenp;
                } else {
                        error = copyin(CAST_USER_ADDR_T(oldlenp), &req.oldlen, sizeof(*oldlenp));
                        if (error)
                                return (error);
                }
        }

        if (oldp) {
                req.oldptr = oldp;
        }

        if (newlen) {
                req.newlen = newlen;
                req.newptr = newp;
        }

        req.oldfunc = sysctl_old_user;
        req.newfunc = sysctl_new_user;
        req.lock = 1;

        do {
            req2 = req;
            error = sysctl_root(0, name, namelen, &req2);
        } while (error == EAGAIN);

        req = req2;

        if (error && error != ENOMEM)
                return (error);

        if (retval) {
                if (req.oldptr && req.oldidx > req.oldlen)
                        *retval = req.oldlen;
                else
                        *retval = req.oldidx;
        }
        return (error);
}

/* Non-standard BSDI extension - only present on their 4.3 net-2 releases */
#define KINFO_BSDI_SYSINFO      (101<<8)

/*
 * Kernel versions of the userland sysctl helper functions.
 *
 * These allow sysctl to be used in the same fashion in both
 * userland and the kernel.
 *
 * Note that some sysctl handlers use copyin/copyout, which
 * may not work correctly.
 */

static int
sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp, size_t newlen)
{

        return(kernel_sysctl(current_proc(), name, namelen, oldp, oldlenp, newp, newlen));
}

static int
sysctlnametomib(const char *name, int *mibp, size_t *sizep)
{
        int oid[2];
        int error;

        /* magic service node */
        oid[0] = 0;
        oid[1] = 3;

        /* look up OID for name */
        *sizep *= sizeof(int);
        error = sysctl(oid, 2, mibp, sizep, (void *)name, strlen(name));
        *sizep /= sizeof(int);
        return(error);
}

int
sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *newp, size_t newlen)
{
        int oid[CTL_MAXNAME + 2];
        int error;
        size_t oidlen;

        /* look up the OID */
        oidlen = CTL_MAXNAME;
        error = sysctlnametomib(name, oid, &oidlen);

        /* now use the OID */
        if (error == 0)
                error = sysctl(oid, oidlen, oldp, oldlenp, newp, newlen);
        return(error);
}