/*      $NetBSD: puffs.c,v 1.129 2022/04/19 20:32:17 rillig Exp $       */

/*
 * Copyright (c) 2005, 2006, 2007  Antti Kantee.  All Rights Reserved.
 *
 * Development of this software was supported by the
 * Google Summer of Code program and the Ulla Tuominen Foundation.
 * The Google SoC project was mentored by Bill Studenmund.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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/cdefs.h>
#if !defined(lint)
__RCSID("$NetBSD: puffs.c,v 1.129 2022/04/19 20:32:17 rillig Exp $");
#endif /* !lint */

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

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <mntopts.h>
#include <paths.h>
#include <pthread.h>
#include <puffs.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "puffs_priv.h"

/* Most file systems want this for opts, so just give it to them */
const struct mntopt puffsmopts[] = {
        MOPT_STDOPTS,
        PUFFSMOPT_STD,
        MOPT_NULL,
};

pthread_mutex_t pu_lock = PTHREAD_MUTEX_INITIALIZER;

#define FILLOP(lower, upper)                                            \
do {                                                                    \
        if (pops->puffs_node_##lower)                                   \
                opmask[PUFFS_VN_##upper] = 1;                           \
} while (0)
static void
fillvnopmask(struct puffs_ops *pops, struct puffs_kargs *pa)
{
        uint8_t *opmask = pa->pa_vnopmask;

        memset(opmask, 0, sizeof(pa->pa_vnopmask));

        FILLOP(create,   CREATE);
        FILLOP(mknod,    MKNOD);
        FILLOP(open,     OPEN);
        FILLOP(close,    CLOSE);
        FILLOP(access,   ACCESS);
        FILLOP(getattr,  GETATTR);
        FILLOP(setattr,  SETATTR);
        FILLOP(poll,     POLL);
        FILLOP(mmap,     MMAP);
        FILLOP(fsync,    FSYNC);
        FILLOP(seek,     SEEK);
        FILLOP(remove,   REMOVE);
        FILLOP(link,     LINK);
        FILLOP(rename,   RENAME);
        FILLOP(mkdir,    MKDIR);
        FILLOP(rmdir,    RMDIR);
        FILLOP(symlink,  SYMLINK);
        FILLOP(readdir,  READDIR);
        FILLOP(readlink, READLINK);
        FILLOP(reclaim,  RECLAIM);
        FILLOP(inactive, INACTIVE);
        FILLOP(print,    PRINT);
        FILLOP(read,     READ);
        FILLOP(write,    WRITE);
        FILLOP(advlock,  ADVLOCK);
        FILLOP(abortop,  ABORTOP);
        FILLOP(pathconf, PATHCONF);

        FILLOP(getextattr,  GETEXTATTR);
        FILLOP(setextattr,  SETEXTATTR);
        FILLOP(listextattr, LISTEXTATTR);
        FILLOP(deleteextattr, DELETEEXTATTR);
        FILLOP(fallocate, FALLOCATE);
        FILLOP(fdiscard, FDISCARD);
}
#undef FILLOP

/*
 * Go over all framev entries and write everything we can.  This is
 * mostly for the benefit of delivering "unmount" to the kernel.
 */
static void
finalpush(struct puffs_usermount *pu)
{
        struct puffs_fctrl_io *fio;

        LIST_FOREACH(fio, &pu->pu_ios, fio_entries) {
                if (fio->stat & FIO_WRGONE)
                        continue;

                puffs__framev_output(pu, fio->fctrl, fio);
        }
}

/*ARGSUSED*/
void
puffs_kernerr_abort(struct puffs_usermount *pu, uint8_t type,
        int error, const char *str, puffs_cookie_t cookie)
{

        warnx("%s: type %d, error %d, cookie %p (%s)", __func__,
            type, error, cookie, str);
        abort();
}

/*ARGSUSED*/
void
puffs_kernerr_log(struct puffs_usermount *pu, uint8_t type,
        int error, const char *str, puffs_cookie_t cookie)
{

        syslog(LOG_WARNING, "%s: type %d, error %d, cookie %p (%s)", __func__,
            type, error, cookie, str);
}

int
puffs_getselectable(struct puffs_usermount *pu)
{

        return pu->pu_fd;
}

uint64_t
puffs__nextreq(struct puffs_usermount *pu)
{
        uint64_t rv;

        PU_LOCK();
        rv = pu->pu_nextreq++ | (uint64_t)1<<63;
        PU_UNLOCK();

        return rv;
}

int
puffs_setblockingmode(struct puffs_usermount *pu, int mode)
{
        int rv, x;

        assert(puffs_getstate(pu) == PUFFS_STATE_RUNNING);

        if (mode != PUFFSDEV_BLOCK && mode != PUFFSDEV_NONBLOCK) {
                errno = EINVAL;
                return -1;
        }

        x = mode;
        rv = ioctl(pu->pu_fd, FIONBIO, &x);

        if (rv == 0) {
                if (mode == PUFFSDEV_BLOCK)
                        pu->pu_state &= ~PU_ASYNCFD;
                else
                        pu->pu_state |= PU_ASYNCFD;
        }

        return rv;
}

int
puffs_getstate(struct puffs_usermount *pu)
{

        return pu->pu_state & PU_STATEMASK;
}

void
puffs_setstacksize(struct puffs_usermount *pu, size_t ss)
{
        long psize, minsize;
        int stackshift;
        int bonus;

        assert(puffs_getstate(pu) == PUFFS_STATE_BEFOREMOUNT);

        psize = sysconf(_SC_PAGESIZE);
        minsize = 4*psize;
        if (ss < (size_t)minsize || ss == PUFFS_STACKSIZE_MIN) {
                if (ss != PUFFS_STACKSIZE_MIN)
                        warnx("%s: adjusting " "stacksize to minimum %ld",
                            __func__, minsize);
                ss = 4*psize;
        }
 
        stackshift = -1;
        bonus = 0;
        while (ss) {
                if (ss & 0x1)
                        bonus++;
                ss >>= 1;
                stackshift++;
        }
        if (bonus > 1) {
                stackshift++;
                warnx("%s: using next power of two: %d", __func__,
                    1 << stackshift);
        }

        pu->pu_cc_stackshift = stackshift;
}

struct puffs_pathobj *
puffs_getrootpathobj(struct puffs_usermount *pu)
{
        struct puffs_node *pnr;

        pnr = pu->pu_pn_root;
        if (pnr == NULL) {
                errno = ENOENT;
                return NULL;
        }

        return &pnr->pn_po;
}

void
puffs_setroot(struct puffs_usermount *pu, struct puffs_node *pn)
{

        pu->pu_pn_root = pn;
}

struct puffs_node *
puffs_getroot(struct puffs_usermount *pu)
{

        return pu->pu_pn_root;
}

void
puffs_setrootinfo(struct puffs_usermount *pu, enum vtype vt,
        size_t vsize, dev_t rdev)
{
        struct puffs_kargs *pargs = pu->pu_kargp;

        if (puffs_getstate(pu) != PUFFS_STATE_BEFOREMOUNT) {
                warnx("%s: call has effect only before mount", __func__);
                return;
        }

        pargs->pa_root_vtype = vt;
        pargs->pa_root_vsize = (voff_t)vsize;
        pargs->pa_root_rdev = rdev;
}

void *
puffs_getspecific(struct puffs_usermount *pu)
{

        return pu->pu_privdata;
}

void
puffs_setspecific(struct puffs_usermount *pu, void *privdata)
{

        pu->pu_privdata = privdata;
}

void
puffs_setmntinfo(struct puffs_usermount *pu,
        const char *mntfromname, const char *puffsname)
{
        struct puffs_kargs *pargs = pu->pu_kargp;

        (void)strlcpy(pargs->pa_mntfromname, mntfromname,
            sizeof(pargs->pa_mntfromname));
        (void)strlcpy(pargs->pa_typename, puffsname,
            sizeof(pargs->pa_typename));
}

size_t
puffs_getmaxreqlen(struct puffs_usermount *pu)
{

        return pu->pu_maxreqlen;
}

void
puffs_setmaxreqlen(struct puffs_usermount *pu, size_t reqlen)
{

        if (puffs_getstate(pu) != PUFFS_STATE_BEFOREMOUNT)
                warnx("%s: call has effect only before mount", __func__);

        pu->pu_kargp->pa_maxmsglen = reqlen;
}

void
puffs_setfhsize(struct puffs_usermount *pu, size_t fhsize, int flags)
{

        if (puffs_getstate(pu) != PUFFS_STATE_BEFOREMOUNT)
                warnx("%s: call has effect only before mount", __func__);

        pu->pu_kargp->pa_fhsize = fhsize;
        pu->pu_kargp->pa_fhflags = flags;
}

void
puffs_setncookiehash(struct puffs_usermount *pu, int nhash)
{

        if (puffs_getstate(pu) != PUFFS_STATE_BEFOREMOUNT)
                warnx("%s: call has effect only before mount", __func__);

        pu->pu_kargp->pa_nhashbuckets = nhash;
}

void
puffs_set_pathbuild(struct puffs_usermount *pu, pu_pathbuild_fn fn)
{

        pu->pu_pathbuild = fn;
}

void
puffs_set_pathtransform(struct puffs_usermount *pu, pu_pathtransform_fn fn)
{

        pu->pu_pathtransform = fn;
}

void
puffs_set_pathcmp(struct puffs_usermount *pu, pu_pathcmp_fn fn)
{

        pu->pu_pathcmp = fn;
}

void
puffs_set_pathfree(struct puffs_usermount *pu, pu_pathfree_fn fn)
{

        pu->pu_pathfree = fn;
}

void
puffs_set_namemod(struct puffs_usermount *pu, pu_namemod_fn fn)
{

        pu->pu_namemod = fn;
}

void
puffs_set_errnotify(struct puffs_usermount *pu, pu_errnotify_fn fn)
{

        pu->pu_errnotify = fn;
}

void
puffs_set_cmap(struct puffs_usermount *pu, pu_cmap_fn fn)
{

        pu->pu_cmap = fn;
}

void
puffs_ml_setloopfn(struct puffs_usermount *pu, puffs_ml_loop_fn lfn)
{

        pu->pu_ml_lfn = lfn;
}

void
puffs_ml_settimeout(struct puffs_usermount *pu, struct timespec *ts)
{

        if (ts == NULL) {
                pu->pu_ml_timep = NULL;
        } else {
                pu->pu_ml_timeout = *ts;
                pu->pu_ml_timep = &pu->pu_ml_timeout;
        }
}

void
puffs_set_prepost(struct puffs_usermount *pu,
        pu_prepost_fn pre, pu_prepost_fn pst)
{

        pu->pu_oppre = pre;
        pu->pu_oppost = pst;
}

void
puffs_setback(struct puffs_cc *pcc, int whatback)
{
        struct puffs_req *preq = puffs__framebuf_getdataptr(pcc->pcc_pb);

        assert(PUFFSOP_OPCLASS(preq->preq_opclass) == PUFFSOP_VN && (
            preq->preq_optype == PUFFS_VN_OPEN ||
            preq->preq_optype == PUFFS_VN_MMAP ||
            preq->preq_optype == PUFFS_VN_REMOVE ||
            preq->preq_optype == PUFFS_VN_RMDIR ||
            preq->preq_optype == PUFFS_VN_INACTIVE));

        preq->preq_setbacks |= whatback & PUFFS_SETBACK_MASK;
}

int
puffs_daemon(struct puffs_usermount *pu, int nochdir, int noclose)
{
        long int n;
        int parent, value, fd;
        bool is_beforemount;

        is_beforemount = (puffs_getstate(pu) < PUFFS_STATE_RUNNING);
        if (is_beforemount)
                if (pipe(pu->pu_dpipe) == -1)
                        return -1;

        switch (fork()) {
        case -1:
                return -1;
        case 0:
                parent = 0;
                break;
        default:
                parent = 1;
                break;
        }
        if (is_beforemount)
                PU_SETSFLAG(pu, PU_PUFFSDAEMON);

        if (parent) {
                if (is_beforemount) {
                        close(pu->pu_dpipe[1]);
                        n = read(pu->pu_dpipe[0], &value, sizeof(int));
                        if (n == -1)
                                err(1, "puffs_daemon");
                        if (n != sizeof(value))
                                errx(1, "puffs_daemon got %ld bytes", n);
                        if (value) {
                                errno = value;
                                err(1, "puffs_daemon");
                        }
                }
                exit(0);
        } else {
                if (setsid() == -1)
                        goto fail;

                if (!nochdir)
                        chdir("/");

                if (!noclose) {
                        fd = open(_PATH_DEVNULL, O_RDWR, 0);
                        if (fd == -1)
                                goto fail;
                        dup2(fd, STDIN_FILENO);
                        dup2(fd, STDOUT_FILENO);
                        dup2(fd, STDERR_FILENO);
                        if (fd > STDERR_FILENO)
                                close(fd);
                }
                return 0;
        }

 fail:
        if (is_beforemount) {
                n = write(pu->pu_dpipe[1], &errno, sizeof(int));
                assert(n == 4);
        }
        return -1;
}

static void
shutdaemon(struct puffs_usermount *pu, int error)
{
        ssize_t n;

        n = write(pu->pu_dpipe[1], &error, sizeof(int));
        assert(n == 4);
        close(pu->pu_dpipe[0]);
        close(pu->pu_dpipe[1]);
        pu->pu_state &= ~PU_PUFFSDAEMON;
}

int
puffs_mount(struct puffs_usermount *pu, const char *dir, int mntflags,
        puffs_cookie_t cookie)
{
        int rv, fd, sverrno;
        char *comfd;

        pu->pu_kargp->pa_root_cookie = cookie;

        /* XXXkludgehere */
        /* kauth doesn't provide this service any longer */
        if (geteuid() != 0)
                mntflags |= MNT_NOSUID | MNT_NODEV;

        /*
         * Undocumented...  Well, documented only here.
         *
         * This is used for imaginative purposes.  If the env variable is
         * set, puffs_mount() doesn't do the regular mount procedure.
         * Rather, it crams the mount data down the comfd and sets comfd as
         * the puffs descriptor.
         *
         * This shouldn't be used unless you can read my mind ( ... or write
         * it, not to mention execute it, but that's starting to get silly).
         */
        if ((comfd = getenv("PUFFS_COMFD")) != NULL) {
                size_t len;

                if (sscanf(comfd, "%d", &pu->pu_fd) != 1) {
                        errno = EINVAL;
                        rv = -1;
                        goto out;
                }
                /* check that what we got at least resembles an fd */
                if (fcntl(pu->pu_fd, F_GETFL) == -1) {
                        rv = -1;
                        goto out;
                }

#define allwrite(buf, len)                                              \
do {                                                                    \
        ssize_t al_rv;                                                  \
        al_rv = write(pu->pu_fd, buf, len);                             \
        if ((size_t)al_rv != len) {                                     \
                if (al_rv != -1)                                        \
                        errno = EIO;                                    \
                rv = -1;                                                \
                goto out;                                               \
        }                                                               \
} while (0)
                len = strlen(dir)+1;
                allwrite(&len, sizeof(len));
                allwrite(dir, len);
                len = strlen(pu->pu_kargp->pa_mntfromname)+1;
                allwrite(&len, sizeof(len));
                allwrite(pu->pu_kargp->pa_mntfromname, len);
                allwrite(&mntflags, sizeof(mntflags));
                len = sizeof(*pu->pu_kargp);
                allwrite(&len, sizeof(len));
                allwrite(pu->pu_kargp, sizeof(*pu->pu_kargp));
                allwrite(&pu->pu_flags, sizeof(pu->pu_flags));
#undef allwrite

                rv = 0;
        } else {
                char rp[MAXPATHLEN];
                size_t rplen,dirlen;

                if (realpath(dir, rp) == NULL) {
                        rv = -1;
                        goto out;
                }

                rplen = strlen(rp);
                dirlen = strlen(dir);
                if (strncmp(dir, rp, rplen) != 0 ||
                    strspn(dir + rplen, "/") != dirlen - rplen) {
                        warnx("%s: `%s' is a %s path.", __func__, dir,
                            dir[0] != '/' ? "relative" : "non canonical");
                        warnx("%s: using `%s' instead.", __func__, rp);
                }

                fd = open(_PATH_PUFFS, O_RDWR);
                if (fd == -1) {
                        warnx("%s: cannot open `%s'", __func__, _PATH_PUFFS);
                        rv = -1;
                        goto out;
                }
                if (fd <= 2)
                        warnx("%s: device fd %d (<= 2), sure this is "
                            "what you want?", __func__, fd);

                pu->pu_kargp->pa_fd = pu->pu_fd = fd;
                if ((rv = mount(MOUNT_PUFFS, rp, mntflags,
                    pu->pu_kargp, sizeof(struct puffs_kargs))) == -1)
                        goto out;
        }

        PU_SETSTATE(pu, PUFFS_STATE_RUNNING);

 out:
        if (rv != 0)
                sverrno = errno;
        else
                sverrno = 0;
        free(pu->pu_kargp);
        pu->pu_kargp = NULL;

        if (PU_GETSFLAG(pu, PU_PUFFSDAEMON))
                shutdaemon(pu, sverrno);

        errno = sverrno;
        return rv;
}

struct puffs_usermount *
puffs_init(struct puffs_ops *pops, const char *mntfromname,
        const char *puffsname, void *priv, uint32_t pflags)
{
        struct puffs_usermount *pu;
        struct puffs_kargs *pargs;
        int sverrno;

        if (puffsname == PUFFS_DEFER)
                puffsname = "n/a";
        if (mntfromname == PUFFS_DEFER)
                mntfromname = "n/a";
        if (priv == PUFFS_DEFER)
                priv = NULL;

        pu = malloc(sizeof(struct puffs_usermount));
        if (pu == NULL)
                goto failfree;
        memset(pu, 0, sizeof(struct puffs_usermount));

        pargs = pu->pu_kargp = malloc(sizeof(struct puffs_kargs));
        if (pargs == NULL)
                goto failfree;
        memset(pargs, 0, sizeof(struct puffs_kargs));

        pargs->pa_vers = PUFFSVERSION;
        pargs->pa_flags = PUFFS_FLAG_KERN(pflags);
        fillvnopmask(pops, pargs);
        puffs_setmntinfo(pu, mntfromname, puffsname);

        puffs_zerostatvfs(&pargs->pa_svfsb);
        pargs->pa_root_cookie = NULL;
        pargs->pa_root_vtype = VDIR;
        pargs->pa_root_vsize = 0;
        pargs->pa_root_rdev = 0;
        pargs->pa_maxmsglen = 0;
        if (/*CONSTCOND*/ sizeof(time_t) == 4)
                pargs->pa_time32 = 1;
        else
                pargs->pa_time32 = 0;

        pu->pu_flags = pflags;
        pu->pu_ops = *pops;
        free(pops); /* XXX */

        pu->pu_privdata = priv;
        pu->pu_cc_stackshift = PUFFS_CC_STACKSHIFT_DEFAULT;
        LIST_INIT(&pu->pu_pnodelst);
        LIST_INIT(&pu->pu_ios);
        LIST_INIT(&pu->pu_ios_rmlist);
        LIST_INIT(&pu->pu_ccmagazin);
        TAILQ_INIT(&pu->pu_sched);

        pu->pu_framectrl[PU_FRAMECTRL_FS].rfb = puffs__fsframe_read;
        pu->pu_framectrl[PU_FRAMECTRL_FS].wfb = puffs__fsframe_write;
        pu->pu_framectrl[PU_FRAMECTRL_FS].cmpfb = puffs__fsframe_cmp;
        pu->pu_framectrl[PU_FRAMECTRL_FS].gotfb = puffs__fsframe_gotframe;
        pu->pu_framectrl[PU_FRAMECTRL_FS].fdnotfn = puffs_framev_unmountonclose;

        /* defaults for some user-settable translation functions */
        pu->pu_cmap = NULL; /* identity translation */

        pu->pu_pathbuild = puffs_stdpath_buildpath;
        pu->pu_pathfree = puffs_stdpath_freepath;
        pu->pu_pathcmp = puffs_stdpath_cmppath;
        pu->pu_pathtransform = NULL;
        pu->pu_namemod = NULL;

        pu->pu_errnotify = puffs_kernerr_log;

        PU_SETSTATE(pu, PUFFS_STATE_BEFOREMOUNT);

        return pu;

 failfree:
        /* can't unmount() from here for obvious reasons */
        sverrno = errno;
        free(pu);
        errno = sverrno;
        return NULL;
}

void
puffs_cancel(struct puffs_usermount *pu, int error)
{
        assert(puffs_getstate(pu) < PUFFS_STATE_RUNNING);
        assert(PU_GETSFLAG(pu, PU_PUFFSDAEMON));
        shutdaemon(pu, error);
        free(pu);
}

/*ARGSUSED1*/
int
puffs_exit(struct puffs_usermount *pu, int unused /* strict compat */)
{
        struct puffs_framebuf *pb;
        struct puffs_req *preq;
        void *winp;
        size_t winlen;
        int sverrno;

        pb = puffs_framebuf_make();
        if (pb == NULL) {
                errno = ENOMEM;
                return -1;
        }

        winlen = sizeof(struct puffs_req);
        if (puffs_framebuf_getwindow(pb, 0, &winp, &winlen) == -1) {
                sverrno = errno;
                puffs_framebuf_destroy(pb);
                errno = sverrno;
                return -1;
        }
        preq = winp;

        preq->preq_buflen = sizeof(struct puffs_req);
        preq->preq_opclass = PUFFSOP_UNMOUNT;
        preq->preq_id = puffs__nextreq(pu);

        puffs_framev_enqueue_justsend(pu, puffs_getselectable(pu), pb, 1, 0);

        return 0;
}

/* no sigset_t static initializer */
static int sigs[NSIG] = { 0, };
static int sigcatch = 0;

int
puffs_unmountonsignal(int sig, bool sigignore)
{

        if (sig < 0 || sig >= (int)NSIG) {
                errno = EINVAL;
                return -1;
        }
        if (sigignore)
                if (signal(sig, SIG_IGN) == SIG_ERR)
                        return -1;

        if (!sigs[sig])
                sigcatch++;
        sigs[sig] = 1;

        return 0;
}

/*
 * Actual mainloop.  This is called from a context which can block.
 * It is called either from puffs_mainloop (indirectly, via
 * puffs_cc_continue() or from puffs_cc_yield()).
 */
void
puffs__theloop(struct puffs_cc *pcc)
{
        struct puffs_usermount *pu = pcc->pcc_pu;
        struct puffs_framectrl *pfctrl;
        struct puffs_fctrl_io *fio;
        struct kevent *curev;
        size_t nchanges;
        int ndone;

        while (puffs_getstate(pu) != PUFFS_STATE_UNMOUNTED) {

                /*
                 * Schedule existing requests.
                 */
                while ((pcc = TAILQ_FIRST(&pu->pu_sched)) != NULL) {
                        TAILQ_REMOVE(&pu->pu_sched, pcc, pcc_schedent);
                        puffs__goto(pcc);
                }

                if (pu->pu_ml_lfn)
                        pu->pu_ml_lfn(pu);

                /* XXX: can we still do these optimizations? */
#if 0
                /*
                 * Do this here, because:
                 *  a) loopfunc might generate some results
                 *  b) it's still "after" event handling (except for round 1)
                 */
                if (puffs_req_putput(ppr) == -1)
                        goto out;
                puffs_req_resetput(ppr);

                /* micro optimization: skip kevent syscall if possible */
                if (pu->pu_nfds == 1 && pu->pu_ml_timep == NULL
                    && (pu->pu_state & PU_ASYNCFD) == 0) {
                        pfctrl = XXX->fctrl;
                        puffs_framev_input(pu, pfctrl, XXX);
                        continue;
                }
#endif

                /* else: do full processing */
                /* Don't bother worrying about O(n) for now */
                LIST_FOREACH(fio, &pu->pu_ios, fio_entries) {
                        if (fio->stat & FIO_WRGONE)
                                continue;

                        pfctrl = fio->fctrl;

                        /*
                         * Try to write out everything to avoid the
                         * need for enabling EVFILT_WRITE.  The likely
                         * case is that we can fit everything into the
                         * socket buffer.
                         */
                        puffs__framev_output(pu, pfctrl, fio);
                }

                /*
                 * Build list of which to enable/disable in writecheck.
                 */
                nchanges = 0;
                LIST_FOREACH(fio, &pu->pu_ios, fio_entries) {
                        if (fio->stat & FIO_WRGONE)
                                continue;

                        /* en/disable write checks for kqueue as needed */
                        assert((FIO_EN_WRITE(fio) && FIO_RM_WRITE(fio)) == 0);
                        if (FIO_EN_WRITE(fio)) {
                                EV_SET(&pu->pu_evs[nchanges], fio->io_fd,
                                    EVFILT_WRITE, EV_ENABLE, 0, 0,
                                    (intptr_t)fio);
                                fio->stat |= FIO_WR;
                                nchanges++;
                        }
                        if (FIO_RM_WRITE(fio)) {
                                EV_SET(&pu->pu_evs[nchanges], fio->io_fd,
                                    EVFILT_WRITE, EV_DISABLE, 0, 0,
                                    (intptr_t)fio);
                                fio->stat &= ~FIO_WR;
                                nchanges++;
                        }
                }

                ndone = kevent(pu->pu_kq, pu->pu_evs, nchanges,
                    pu->pu_evs, pu->pu_nevs, pu->pu_ml_timep);

                if (ndone == -1) {
                        if (errno != EINTR)
                                break;
                        else
                                continue;
                }

                /* uoptimize */
                if (ndone == 0)
                        continue;

                /* iterate over the results */
                for (curev = pu->pu_evs; ndone--; curev++) {
                        int what;

#if 0
                        /* get & possibly dispatch events from kernel */
                        if (curev->ident == puffsfd) {
                                if (puffs_req_handle(pgr, ppr, 0) == -1)
                                        goto out;
                                continue;
                        }
#endif

                        fio = (void *)curev->udata;
                        if (__predict_true(fio))
                                pfctrl = fio->fctrl;
                        else
                                pfctrl = NULL;
                        if (curev->flags & EV_ERROR) {
                                assert(curev->filter == EVFILT_WRITE);
                                fio->stat &= ~FIO_WR;

                                /* XXX: how to know if it's a transient error */
                                puffs__framev_writeclose(pu, fio,
                                    (int)curev->data);
                                puffs__framev_notify(fio, PUFFS_FBIO_ERROR);
                                continue;
                        }

                        what = 0;
                        switch (curev->filter) {
                        case EVFILT_READ:
                                puffs__framev_input(pu, pfctrl, fio);
                                what |= PUFFS_FBIO_READ;
                                break;
                        case EVFILT_WRITE:
                                puffs__framev_output(pu, pfctrl, fio);
                                what |= PUFFS_FBIO_WRITE;
                                break;
                        case EVFILT_SIGNAL:
                                if ((pu->pu_state & PU_DONEXIT) == 0) {
                                        PU_SETSFLAG(pu, PU_DONEXIT);
                                        puffs_exit(pu, 0);
                                }
                                break;
                        default:
                                warn("unhandled filter %d", curev->filter);
                        }
                        if (what)
                                puffs__framev_notify(fio, what);
                }

                /*
                 * Really free fd's now that we don't have references
                 * to them.
                 */
                while ((fio = LIST_FIRST(&pu->pu_ios_rmlist)) != NULL) {
                        LIST_REMOVE(fio, fio_entries);
                        free(fio);
                }
        }

        if (puffs__cc_restoremain(pu) == -1)
                warn("cannot restore main context.  impending doom");
}
int
puffs_mainloop(struct puffs_usermount *pu)
{
        struct puffs_fctrl_io *fio;
        struct puffs_cc *pcc;
        struct kevent *curev;
        size_t nevs;
        int sverrno, i;

        assert(puffs_getstate(pu) >= PUFFS_STATE_RUNNING);

        pu->pu_kq = kqueue();
        if (pu->pu_kq == -1)
                goto out;
        pu->pu_state |= PU_HASKQ;

        puffs_setblockingmode(pu, PUFFSDEV_NONBLOCK);
        if (puffs__framev_addfd_ctrl(pu, puffs_getselectable(pu),
            PUFFS_FBIO_READ | PUFFS_FBIO_WRITE,
            &pu->pu_framectrl[PU_FRAMECTRL_FS]) == -1)
                goto out;

        nevs = pu->pu_nevs + sigcatch;
        if (reallocarr(&pu->pu_evs, nevs, sizeof(struct kevent)) != 0) {
                errno = ENOMEM;
                goto out;
        }
        pu->pu_nevs = nevs;

        curev = pu->pu_evs;

        LIST_FOREACH(fio, &pu->pu_ios, fio_entries) {
                EV_SET(curev, fio->io_fd, EVFILT_READ, EV_ADD,
                    0, 0, (intptr_t)fio);
                curev++;
                EV_SET(curev, fio->io_fd, EVFILT_WRITE, EV_ADD | EV_DISABLE,
                    0, 0, (intptr_t)fio);
                curev++;
        }
        for (i = 0; i < NSIG; i++) {
                if (sigs[i]) {
                        EV_SET(curev, i, EVFILT_SIGNAL, EV_ADD | EV_ENABLE,
                            0, 0, 0);
                        curev++;
                }
        }
        assert(curev - pu->pu_evs == (ssize_t)pu->pu_nevs);
        if (kevent(pu->pu_kq, pu->pu_evs, pu->pu_nevs, NULL, 0, NULL) == -1)
                goto out;

        pu->pu_state |= PU_INLOOP;

        /*
         * Create alternate execution context and jump to it.  Note
         * that we come "out" of savemain twice.  Where we come out
         * of it depends on the architecture.  If the return address is
         * stored on the stack, we jump out from puffs_cc_continue(),
         * for a register return address from puffs__cc_savemain().
         * PU_MAINRESTORE makes sure we DTRT in both cases.
         */
        if (puffs__cc_create(pu, puffs__theloop, &pcc) == -1) {
                goto out;
        }

#if 0
        if (puffs__cc_savemain(pu) == -1) {
                goto out;
        }
#else
        /*
         * XXX
         * puffs__cc_savemain() uses getcontext() and then returns.
         * the caller (this function) may overwrite the stack frame
         * of puffs__cc_savemain(), so when we call setcontext() later and
         * return from puffs__cc_savemain() again, the return address or
         * saved stack pointer can be garbage.
         * avoid this by calling getcontext() directly here.
         */
        extern int puffs_fakecc;
        if (!puffs_fakecc) {
                PU_CLRSFLAG(pu, PU_MAINRESTORE);
                if (getcontext(&pu->pu_mainctx) == -1) {
                        goto out;
                }
        }
#endif

        if ((pu->pu_state & PU_MAINRESTORE) == 0)
                puffs_cc_continue(pcc);

        finalpush(pu);
        errno = 0;

 out:
        /* store the real error for a while */
        sverrno = errno;

        errno = sverrno;
        if (errno)
                return -1;
        else
                return 0;
}