Merge commit '1f1540205fa6366266184180654434272c425ac2'

[unleashed.git] / usr / src / lib / libsysevent / libevchannel.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 (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <stdio.h>
#include <ctype.h>
#include <fcntl.h>
#include <errno.h>
#include <door.h>
#include <unistd.h>
#include <stddef.h>
#include <stdlib.h>
#include <strings.h>
#include <pthread.h>
#include <atomic.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/varargs.h>
#include <sys/sysevent.h>
#include <sys/sysevent_impl.h>

#include "libsysevent.h"
#include "libsysevent_impl.h"

/*
 * The functions below deal with the General Purpose Event Handling framework
 *
 * sysevent_evc_bind        - create/bind application to named channel
 * sysevent_evc_unbind      - unbind from previously bound/created channel
 * sysevent_evc_subscribe   - subscribe to existing event channel
 * sysevent_evc_unsubscribe - unsubscribe from existing event channel
 * sysevent_evc_publish     - generate a system event via an event channel
 * sysevent_evc_control     - various channel based control operation
 */

static void kill_door_servers(evchan_subscr_t *);

#define misaligned(p)   ((uintptr_t)(p) & 3)    /* 4-byte alignment required */

static pthread_key_t nrkey = PTHREAD_ONCE_KEY_NP;

/*
 * If the current thread is a door server thread servicing a door created
 * for us in sysevent_evc_xsubscribe, then an attempt to unsubscribe from
 * within door invocation context on the same channel will deadlock in the
 * kernel waiting for our own invocation to complete.  Such calls are
 * forbidden, and we abort if they are encountered (better than hanging
 * unkillably).
 *
 * We'd like to offer this detection to subscriptions established with
 * sysevent_evc_subscribe, but we don't have control over the door service
 * threads in that case.  Perhaps the fix is to always use door_xcreate
 * even for sysevent_evc_subscribe?
 */
static boolean_t
will_deadlock(evchan_t *scp)
{
        evchan_subscr_t *subp = pthread_getspecific(nrkey);
        evchan_impl_hdl_t *hdl = EVCHAN_IMPL_HNDL(scp);

        return (subp != NULL && subp->ev_subhead == hdl ? B_TRUE : B_FALSE);
}

/*
 * Check syntax of a channel name
 */
static int
sysevent_is_chan_name(const char *str)
{
        for (; *str != '\0'; str++) {
                if (!EVCH_ISCHANCHAR(*str))
                        return (0);
        }

        return (1);
}

/*
 * Check for printable characters
 */
static int
strisprint(const char *s)
{
        for (; *s != '\0'; s++) {
                if (*s < ' ' || *s > '~')
                        return (0);
        }

        return (1);
}

/*
 * sysevent_evc_bind - Create/bind application to named channel
 */
int
sysevent_evc_bind(const char *channel, evchan_t **scpp, uint32_t flags)
{
        int chanlen;
        evchan_t *scp;
        sev_bind_args_t uargs;
        int ec;

        if (scpp == NULL || misaligned(scpp)) {
                return (errno = EINVAL);
        }

        /* Provide useful value in error case */
        *scpp = NULL;

        if (channel == NULL ||
            (chanlen = strlen(channel) + 1) > MAX_CHNAME_LEN) {
                return (errno = EINVAL);
        }

        /* Check channel syntax */
        if (!sysevent_is_chan_name(channel)) {
                return (errno = EINVAL);
        }

        if (flags & ~EVCH_B_FLAGS) {
                return (errno = EINVAL);
        }

        scp = calloc(1, sizeof (evchan_impl_hdl_t));
        if (scp == NULL) {
                return (errno = ENOMEM);
        }

        /*
         * Enable sysevent driver.  Fallback if the device link doesn't exist;
         * this situation can arise if a channel is bound early in system
         * startup, prior to devfsadm(8) being invoked.
         */
        EV_FD(scp) = open(DEVSYSEVENT, O_RDWR);
        if (EV_FD(scp) == -1) {
                if (errno != ENOENT) {
                        ec = errno == EACCES ? EPERM : errno;
                        free(scp);
                        return (errno = ec);
                }

                EV_FD(scp) = open(DEVICESYSEVENT, O_RDWR);
                if (EV_FD(scp) == -1) {
                        ec = errno == EACCES ? EPERM : errno;
                        free(scp);
                        return (errno = ec);
                }
        }

        /*
         * Force to close the fd's when process is doing exec.
         * The driver will then release stale binding handles.
         * The driver will release also the associated subscriptions
         * if EVCH_SUB_KEEP flag was not set.
         */
        (void) fcntl(EV_FD(scp), F_SETFD, FD_CLOEXEC);

        uargs.chan_name.name = (uintptr_t)channel;
        uargs.chan_name.len = chanlen;
        uargs.flags = flags;

        if (ioctl(EV_FD(scp), SEV_CHAN_OPEN, &uargs) != 0) {
                ec = errno;
                (void) close(EV_FD(scp));
                free(scp);
                return (errno = ec);
        }

        /* Needed to detect a fork() */
        EV_PID(scp) = getpid();
        (void) mutex_init(EV_LOCK(scp), USYNC_THREAD, NULL);

        *scpp = scp;

        return (0);
}

/*
 * sysevent_evc_unbind - Unbind from previously bound/created channel
 */
int
sysevent_evc_unbind(evchan_t *scp)
{
        sev_unsubscribe_args_t uargs;
        evchan_subscr_t *subp;
        int errcp;

        if (scp == NULL || misaligned(scp))
                return (errno = EINVAL);

        if (will_deadlock(scp))
                return (errno = EDEADLK);

        (void) mutex_lock(EV_LOCK(scp));

        /*
         * Unsubscribe, if we are in the process which did the bind.
         */
        if (EV_PID(scp) == getpid()) {
                uargs.sid.name = '\0';
                uargs.sid.len = 0;
                /*
                 * The unsubscribe ioctl will block until all door upcalls have
                 * drained.
                 */
                if (ioctl(EV_FD(scp), SEV_UNSUBSCRIBE, (intptr_t)&uargs) != 0) {
                        errcp = errno;
                        (void) mutex_unlock(EV_LOCK(scp));
                        return (errno = errcp);
                }
        }

        while ((subp =  EV_SUB_NEXT(scp)) != NULL) {
                EV_SUB_NEXT(scp) = subp->evsub_next;

                /* If door_xcreate was applied we can clean up */
                if (subp->evsub_attr)
                        kill_door_servers(subp);

                if (door_revoke(subp->evsub_door_desc) != 0 && errno == EPERM)
                        (void) close(subp->evsub_door_desc);

                free(subp->evsub_sid);
                free(subp);
        }

        (void) mutex_unlock(EV_LOCK(scp));

        /*
         * The close of the driver will do the unsubscribe if a) it is the last
         * close and b) we are in a child which inherited subscriptions.
         */
        (void) close(EV_FD(scp));
        (void) mutex_destroy(EV_LOCK(scp));
        free(scp);

        return (0);
}

/*
 * sysevent_evc_publish - Generate a system event via an event channel
 */
int
sysevent_evc_publish(evchan_t *scp, const char *class,
    const char *subclass, const char *vendor,
    const char *pub_name, nvlist_t *attr_list,
    uint32_t flags)
{
        sysevent_t *ev;
        sev_publish_args_t uargs;
        int rc;
        int ec;

        if (scp == NULL || misaligned(scp)) {
                return (errno = EINVAL);
        }

        /* No inheritance of binding handles via fork() */
        if (EV_PID(scp) != getpid()) {
                return (errno = EINVAL);
        }

        ev = sysevent_alloc_event((char *)class, (char *)subclass,
            (char *)vendor, (char *)pub_name, attr_list);
        if (ev == NULL) {
                return (errno);
        }

        uargs.ev.name = (uintptr_t)ev;
        uargs.ev.len = SE_SIZE(ev);
        uargs.flags = flags;

        (void) mutex_lock(EV_LOCK(scp));

        rc = ioctl(EV_FD(scp), SEV_PUBLISH, (intptr_t)&uargs);
        ec = errno;

        (void) mutex_unlock(EV_LOCK(scp));

        sysevent_free(ev);

        if (rc != 0) {
                return (ec);
        }
        return (0);
}

/*
 * Generic callback which catches events from the kernel and calls
 * subscribers call back routine.
 *
 * Kernel guarantees that door_upcalls are disabled when unsubscription
 * was issued that's why cookie points always to a valid evchan_subscr_t *.
 *
 * Furthermore it's not necessary to lock subp because the sysevent
 * framework guarantees no unsubscription until door_return.
 */
/*ARGSUSED3*/
static void
door_upcall(void *cookie, char *args, size_t alen,
    door_desc_t *ddp, uint_t ndid)
{
        evchan_subscr_t *subp = EVCHAN_SUBSCR(cookie);
        int rval = 0;

        /*
         * If we've been invoked simply to kill the thread then
         * exit now.
         */
        if (subp->evsub_state == EVCHAN_SUB_STATE_CLOSING)
                pthread_exit(NULL);

        if (args == NULL || alen <= (size_t)0) {
                /* Skip callback execution */
                rval = EINVAL;
        } else {
                rval = subp->evsub_func((sysevent_t *)(void *)args,
                    subp->evsub_cookie);
        }

        /*
         * Fill in return values for door_return
         */
        alen = sizeof (rval);
        bcopy(&rval, args, alen);

        (void) door_return(args, alen, NULL, 0);
}

static pthread_once_t xsub_thrattr_once = PTHREAD_ONCE_INIT;
static pthread_attr_t xsub_thrattr;

static void
xsub_thrattr_init(void)
{
        (void) pthread_attr_init(&xsub_thrattr);
        (void) pthread_attr_setdetachstate(&xsub_thrattr,
            PTHREAD_CREATE_DETACHED);
        (void) pthread_attr_setscope(&xsub_thrattr, PTHREAD_SCOPE_SYSTEM);
}

/*
 * Our door server create function is only called during initial
 * door_xcreate since we specify DOOR_NO_DEPLETION_CB.
 */
int
xsub_door_server_create(door_info_t *dip, void *(*startf)(void *),
    void *startfarg, void *cookie)
{
        evchan_subscr_t *subp = EVCHAN_SUBSCR(cookie);
        struct sysevent_subattr_impl *xsa = subp->evsub_attr;
        pthread_attr_t *thrattr;
        sigset_t oset;
        int err;

        if (subp->evsub_state == EVCHAN_SUB_STATE_CLOSING)
                return (0);     /* shouldn't happen, but just in case */

        /*
         * If sysevent_evc_xsubscribe was called electing to use a
         * different door server create function then let it take it
         * from here.
         */
        if (xsa->xs_thrcreate) {
                return (xsa->xs_thrcreate(dip, startf, startfarg,
                    xsa->xs_thrcreate_cookie));
        }

        if (xsa->xs_thrattr == NULL) {
                (void) pthread_once(&xsub_thrattr_once, xsub_thrattr_init);
                thrattr = &xsub_thrattr;
        } else {
                thrattr = xsa->xs_thrattr;
        }

        (void) pthread_sigmask(SIG_SETMASK, &xsa->xs_sigmask, &oset);
        err = pthread_create(NULL, thrattr, startf, startfarg);
        (void) pthread_sigmask(SIG_SETMASK, &oset, NULL);

        return (err == 0 ? 1 : -1);
}

void
xsub_door_server_setup(void *cookie)
{
        evchan_subscr_t *subp = EVCHAN_SUBSCR(cookie);
        struct sysevent_subattr_impl *xsa = subp->evsub_attr;

        if (xsa->xs_thrsetup == NULL) {
                (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
                (void) pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
        }

        (void) pthread_setspecific(nrkey, (void *)subp);

        if (xsa->xs_thrsetup)
                xsa->xs_thrsetup(xsa->xs_thrsetup_cookie);
}

/*
 * Cause private door server threads to exit.  We have already performed the
 * unsubscribe ioctl which stops new invocations and waits until all
 * existing invocations are complete.  So all server threads should be
 * blocked in door_return.  The door has not yet been revoked.  We will
 * invoke repeatedly after setting the evsub_state to be noticed on
 * wakeup; each invocation will result in the death of one server thread.
 *
 * You'd think it would be easier to kill these threads, such as through
 * pthread_cancel.  Unfortunately door_return is not a cancellation point,
 * and if you do cancel a thread blocked in door_return the EINTR check in
 * the door_return assembly logic causes us to loop with EINTR forever!
 */
static void
kill_door_servers(evchan_subscr_t *subp)
{
        door_arg_t da;

        bzero(&da, sizeof (da));
        subp->evsub_state = EVCHAN_SUB_STATE_CLOSING;
        membar_producer();

        (void) door_call(subp->evsub_door_desc, &da);
}

static int
sysevent_evc_subscribe_cmn(evchan_t *scp, const char *sid, const char *class,
    int (*event_handler)(sysevent_t *ev, void *cookie),
    void *cookie, uint32_t flags, struct sysevent_subattr_impl *xsa)
{
        evchan_subscr_t *subp;
        int upcall_door;
        sev_subscribe_args_t uargs;
        uint32_t sid_len;
        uint32_t class_len;
        int ec;

        if (scp == NULL || misaligned(scp) || sid == NULL || class == NULL) {
                return (errno = EINVAL);
        }

        /* No inheritance of binding handles via fork() */
        if (EV_PID(scp) != getpid()) {
                return (errno = EINVAL);
        }

        if ((sid_len = strlen(sid) + 1) > MAX_SUBID_LEN || sid_len == 1 ||
            (class_len = strlen(class) + 1) > MAX_CLASS_LEN) {
                return (errno = EINVAL);
        }

        /* Check for printable characters */
        if (!strisprint(sid)) {
                return (errno = EINVAL);
        }

        if (event_handler == NULL) {
                return (errno = EINVAL);
        }

        if (pthread_key_create_once_np(&nrkey, NULL) != 0)
                return (errno); /* ENOMEM or EAGAIN */

        /* Create subscriber data */
        if ((subp = calloc(1, sizeof (evchan_subscr_t))) == NULL) {
                return (errno);
        }

        if ((subp->evsub_sid = strdup(sid)) == NULL) {
                ec = errno;
                free(subp);
                return (ec);
        }

        /*
         * EC_ALL string will not be copied to kernel - NULL is assumed
         */
        if (strcmp(class, EC_ALL) == 0) {
                class = NULL;
                class_len = 0;
        }

        /*
         * Fill this in now for the xsub_door_server_setup dance
         */
        subp->ev_subhead = EVCHAN_IMPL_HNDL(scp);
        subp->evsub_state = EVCHAN_SUB_STATE_ACTIVE;

        if (xsa == NULL) {
                upcall_door = door_create(door_upcall, (void *)subp,
                    DOOR_REFUSE_DESC | DOOR_NO_CANCEL);
        } else {
                subp->evsub_attr = xsa;

                /*
                 * Create a private door with exactly one thread to
                 * service the callbacks (the GPEC kernel implementation
                 * serializes deliveries for each subscriber id).
                 */
                upcall_door = door_xcreate(door_upcall, (void *)subp,
                    DOOR_REFUSE_DESC | DOOR_NO_CANCEL | DOOR_NO_DEPLETION_CB,
                    xsub_door_server_create, xsub_door_server_setup,
                    (void *)subp, 1);
        }

        if (upcall_door == -1) {
                ec = errno;
                free(subp->evsub_sid);
                free(subp);
                return (ec);
        }

        /* Complete subscriber information */
        subp->evsub_door_desc = upcall_door;
        subp->evsub_func = event_handler;
        subp->evsub_cookie = cookie;

        (void) mutex_lock(EV_LOCK(scp));

        uargs.sid.name = (uintptr_t)sid;
        uargs.sid.len = sid_len;
        uargs.class_info.name = (uintptr_t)class;
        uargs.class_info.len = class_len;
        uargs.door_desc = subp->evsub_door_desc;
        uargs.flags = flags;
        if (ioctl(EV_FD(scp), SEV_SUBSCRIBE, (intptr_t)&uargs) != 0) {
                ec = errno;
                (void) mutex_unlock(EV_LOCK(scp));
                if (xsa)
                        kill_door_servers(subp);
                (void) door_revoke(upcall_door);
                free(subp->evsub_sid);
                free(subp);
                return (ec);
        }

        /* Attach to subscriber list */
        subp->evsub_next = EV_SUB_NEXT(scp);
        EV_SUB_NEXT(scp) = subp;

        (void) mutex_unlock(EV_LOCK(scp));

        return (0);
}

/*
 * sysevent_evc_subscribe - subscribe to an existing event channel
 * using a non-private door (which will create as many server threads
 * as the apparent maximum concurrency requirements suggest).
 */
int
sysevent_evc_subscribe(evchan_t *scp, const char *sid, const char *class,
    int (*event_handler)(sysevent_t *ev, void *cookie),
    void *cookie, uint32_t flags)
{
        return (sysevent_evc_subscribe_cmn(scp, sid, class, event_handler,
            cookie, flags, NULL));
}

static void
subattr_dfltinit(struct sysevent_subattr_impl *xsa)
{
        (void) sigfillset(&xsa->xs_sigmask);
        (void) sigdelset(&xsa->xs_sigmask, SIGABRT);
}

static struct sysevent_subattr_impl dfltsa;
pthread_once_t dfltsa_inited = PTHREAD_ONCE_INIT;

static void
init_dfltsa(void)
{
        subattr_dfltinit(&dfltsa);
}

/*
 * sysevent_evc_subscribe - subscribe to an existing event channel
 * using a private door with control over thread creation.
 */
int
sysevent_evc_xsubscribe(evchan_t *scp, const char *sid, const char *class,
    int (*event_handler)(sysevent_t *ev, void *cookie),
    void *cookie, uint32_t flags, sysevent_subattr_t *attr)
{
        struct sysevent_subattr_impl *xsa;

        if (attr != NULL) {
                xsa = (struct sysevent_subattr_impl *)attr;
        } else {
                xsa = &dfltsa;
                (void) pthread_once(&dfltsa_inited, init_dfltsa);
        }

        return (sysevent_evc_subscribe_cmn(scp, sid, class, event_handler,
            cookie, flags, xsa));
}

sysevent_subattr_t *
sysevent_subattr_alloc(void)
{
        struct sysevent_subattr_impl *xsa = calloc(1, sizeof (*xsa));

        if (xsa != NULL)
                subattr_dfltinit(xsa);

        return (xsa != NULL ? (sysevent_subattr_t *)xsa : NULL);
}

void
sysevent_subattr_free(sysevent_subattr_t *attr)
{
        struct sysevent_subattr_impl *xsa =
            (struct sysevent_subattr_impl *)attr;

        free(xsa);
}

void
sysevent_subattr_thrcreate(sysevent_subattr_t *attr,
    door_xcreate_server_func_t *thrcreate, void *cookie)
{
        struct sysevent_subattr_impl *xsa =
            (struct sysevent_subattr_impl *)attr;

        xsa->xs_thrcreate = thrcreate;
        xsa->xs_thrcreate_cookie = cookie;
}

void
sysevent_subattr_thrsetup(sysevent_subattr_t *attr,
    door_xcreate_thrsetup_func_t *thrsetup, void *cookie)
{
        struct sysevent_subattr_impl *xsa =
            (struct sysevent_subattr_impl *)attr;

        xsa->xs_thrsetup = thrsetup;
        xsa->xs_thrsetup_cookie = cookie;
}

void
sysevent_subattr_sigmask(sysevent_subattr_t *attr, sigset_t *set)
{
        struct sysevent_subattr_impl *xsa =
            (struct sysevent_subattr_impl *)attr;

        if (set) {
                xsa->xs_sigmask = *set;
        } else {
                (void) sigfillset(&xsa->xs_sigmask);
                (void) sigdelset(&xsa->xs_sigmask, SIGABRT);
        }
}

void
sysevent_subattr_thrattr(sysevent_subattr_t *attr, pthread_attr_t *thrattr)
{
        struct sysevent_subattr_impl *xsa =
            (struct sysevent_subattr_impl *)attr;

        xsa->xs_thrattr = thrattr;
}

/*
 * sysevent_evc_unsubscribe - Unsubscribe from an existing event channel
 */
int
sysevent_evc_unsubscribe(evchan_t *scp, const char *sid)
{
        int all_subscribers = 0;
        sev_unsubscribe_args_t uargs;
        evchan_subscr_t *subp, *prevsubp, *tofree;
        int errcp;
        int rc;

        if (scp == NULL || misaligned(scp))
                return (errno = EINVAL);

        if (sid == NULL || strlen(sid) == 0 ||
            (strlen(sid) >= MAX_SUBID_LEN))
                return (errno = EINVAL);

        /* No inheritance of binding handles via fork() */
        if (EV_PID(scp) != getpid())
                return (errno = EINVAL);

        if (strcmp(sid, EVCH_ALLSUB) == 0) {
                all_subscribers++;
                /* Indicates all subscriber id's for this channel */
                uargs.sid.name = '\0';
                uargs.sid.len = 0;
        } else {
                uargs.sid.name = (uintptr_t)sid;
                uargs.sid.len = strlen(sid) + 1;
        }

        if (will_deadlock(scp))
                return (errno = EDEADLK);

        (void) mutex_lock(EV_LOCK(scp));

        /*
         * The unsubscribe ioctl will block until all door upcalls have drained.
         */
        rc = ioctl(EV_FD(scp), SEV_UNSUBSCRIBE, (intptr_t)&uargs);

        if (rc != 0) {
                errcp = errno;
                (void) mutex_unlock(EV_LOCK(scp));
                return (errno = errcp); /* EFAULT, ENXIO, EINVAL possible */
        }


        /*
         * Search for the matching subscriber.  If EVCH_ALLSUB was specified
         * then the ioctl above will have returned 0 even if there are
         * no subscriptions, so the initial EV_SUB_NEXT can be NULL.
         */
        prevsubp = NULL;
        subp =  EV_SUB_NEXT(scp);
        while (subp != NULL) {
                if (all_subscribers || strcmp(subp->evsub_sid, sid) == 0) {
                        if (prevsubp == NULL) {
                                EV_SUB_NEXT(scp) = subp->evsub_next;
                        } else {
                                prevsubp->evsub_next = subp->evsub_next;
                        }

                        tofree = subp;
                        subp = subp->evsub_next;

                        /* If door_xcreate was applied we can clean up */
                        if (tofree->evsub_attr)
                                kill_door_servers(tofree);

                        (void) door_revoke(tofree->evsub_door_desc);
                        free(tofree->evsub_sid);
                        free(tofree);

                        /* Freed single subscriber already? */
                        if (all_subscribers == 0)
                                break;
                } else {
                        prevsubp = subp;
                        subp = subp->evsub_next;
                }
        }

        (void) mutex_unlock(EV_LOCK(scp));

        return (0);
}

/*
 * sysevent_evc_control - Various channel based control operation
 */
int
sysevent_evc_control(evchan_t *scp, int cmd, /* arg */ ...)
{
        va_list ap;
        uint32_t *chlenp;
        sev_control_args_t uargs;
        int rc = 0;

        if (scp == NULL || misaligned(scp)) {
                return (errno = EINVAL);
        }

        /* No inheritance of binding handles via fork() */
        if (EV_PID(scp) != getpid()) {
                return (errno = EINVAL);
        }

        va_start(ap, cmd);

        uargs.cmd = cmd;

        (void) mutex_lock(EV_LOCK(scp));

        switch (cmd) {
        case EVCH_GET_CHAN_LEN:
        case EVCH_GET_CHAN_LEN_MAX:
                chlenp = va_arg(ap, uint32_t *);
                if (chlenp == NULL || misaligned(chlenp)) {
                        rc = EINVAL;
                        break;
                }
                rc = ioctl(EV_FD(scp), SEV_CHAN_CONTROL, (intptr_t)&uargs);
                *chlenp = uargs.value;
                break;

        case EVCH_SET_CHAN_LEN:
                /* Range change will be handled in framework */
                uargs.value = va_arg(ap, uint32_t);
                rc = ioctl(EV_FD(scp), SEV_CHAN_CONTROL, (intptr_t)&uargs);
                break;

        default:
                rc = EINVAL;
        }

        (void) mutex_unlock(EV_LOCK(scp));

        if (rc == -1) {
                rc = errno;
        }

        va_end(ap);

        return (errno = rc);
}

int
sysevent_evc_setpropnvl(evchan_t *scp, nvlist_t *nvl)
{
        sev_propnvl_args_t uargs;
        char *buf = NULL;
        size_t nvlsz = 0;
        int rc;

        if (scp == NULL || misaligned(scp))
                return (errno = EINVAL);

        if (nvl != NULL &&
            nvlist_pack(nvl, &buf, &nvlsz, NV_ENCODE_NATIVE, 0) != 0)
                return (errno);

        uargs.packednvl.name = (uint64_t)(uintptr_t)buf;
        uargs.packednvl.len = (uint32_t)nvlsz;

        rc = ioctl(EV_FD(scp), SEV_SETPROPNVL, (intptr_t)&uargs);

        free(buf);

        return (rc);
}

int
sysevent_evc_getpropnvl(evchan_t *scp, nvlist_t **nvlp)
{
        sev_propnvl_args_t uargs;
        char buf[1024], *bufp = buf;    /* stack buffer */
        size_t sz = sizeof (buf);
        char *buf2 = NULL;              /* allocated if stack buf too small */
        int64_t expgen = -1;
        int rc;

        if (scp == NULL || misaligned(scp) || nvlp == NULL)
                return (errno = EINVAL);

        *nvlp = NULL;

again:
        uargs.packednvl.name = (uint64_t)(uintptr_t)bufp;
        uargs.packednvl.len = (uint32_t)sz;

        rc = ioctl(EV_FD(scp), SEV_GETPROPNVL, (intptr_t)&uargs);

        if (rc == E2BIG)
                return (errno = E2BIG); /* driver refuses to copyout */

        /*
         * If the packed nvlist is too big for the buffer size we offered
         * then the ioctl returns EOVERFLOW and indicates in the 'len'
         * the size required for the current property nvlist generation
         * (itself returned in the generation member).
         */
        if (rc == EOVERFLOW &&
            (buf2 == NULL || uargs.generation != expgen)) {
                free(buf2);

                if ((sz = uargs.packednvl.len) > 1024 * 1024)
                        return (E2BIG);

                bufp = buf2 = malloc(sz);

                if (buf2 == NULL)
                        return (errno = ENOMEM);

                expgen = uargs.generation;
                goto again;
        }

        /*
         * The chan prop nvlist can be absent, in which case the ioctl
         * returns success and uargs.packednvl.len of 0;  we have already
         * set *nvlp to NULL.  Otherwise we must unpack the nvl.
         */
        if (rc == 0 && uargs.packednvl.len != 0 &&
            nvlist_unpack(bufp, uargs.packednvl.len, nvlp, 0) != 0)
                rc = EINVAL;

        free(buf2);

        return (rc ? errno = rc : 0);
}