/*      $NetBSD: fdesc_vnops.c,v 1.140 2022/03/27 17:10:55 christos Exp $       */

/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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.
 *
 *      @(#)fdesc_vnops.c       8.17 (Berkeley) 5/22/95
 *
 * #Id: fdesc_vnops.c,v 1.12 1993/04/06 16:17:17 jsp Exp #
 */

/*
 * /dev/fd Filesystem
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: fdesc_vnops.c,v 1.140 2022/03/27 17:10:55 christos Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/socketvar.h>
#include <sys/filedesc.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/dirent.h>
#include <sys/tty.h>
#include <sys/kauth.h>
#include <sys/atomic.h>

#include <miscfs/fdesc/fdesc.h>
#include <miscfs/genfs/genfs.h>

#define cttyvp(p) ((p)->p_lflag & PL_CONTROLT ? (p)->p_session->s_ttyvp : NULL)

dev_t devctty;

#if (FD_STDIN != FD_STDOUT-1) || (FD_STDOUT != FD_STDERR-1)
FD_STDIN, FD_STDOUT, FD_STDERR must be a sequence n, n+1, n+2
#endif

int     fdesc_lookup(void *);
int     fdesc_open(void *);
int     fdesc_getattr(void *);
int     fdesc_setattr(void *);
int     fdesc_read(void *);
int     fdesc_write(void *);
int     fdesc_ioctl(void *);
int     fdesc_poll(void *);
int     fdesc_kqfilter(void *);
int     fdesc_readdir(void *);
int     fdesc_readlink(void *);
int     fdesc_inactive(void *);
int     fdesc_reclaim(void *);
int     fdesc_print(void *);
int     fdesc_pathconf(void *);

static int fdesc_attr(int, struct vattr *, kauth_cred_t);

int (**fdesc_vnodeop_p)(void *);
const struct vnodeopv_entry_desc fdesc_vnodeop_entries[] = {
        { &vop_default_desc, vn_default_error },
        { &vop_parsepath_desc, genfs_parsepath },       /* parsepath */
        { &vop_lookup_desc, fdesc_lookup },             /* lookup */
        { &vop_create_desc, genfs_eopnotsupp },         /* create */
        { &vop_mknod_desc, genfs_eopnotsupp },          /* mknod */
        { &vop_open_desc, fdesc_open },                 /* open */
        { &vop_close_desc, genfs_nullop },              /* close */
        { &vop_access_desc, genfs_nullop },             /* access */
        { &vop_accessx_desc, genfs_accessx },           /* accessx */
        { &vop_getattr_desc, fdesc_getattr },           /* getattr */
        { &vop_setattr_desc, fdesc_setattr },           /* setattr */
        { &vop_read_desc, fdesc_read },                 /* read */
        { &vop_write_desc, fdesc_write },               /* write */
        { &vop_fallocate_desc, genfs_eopnotsupp },      /* fallocate */
        { &vop_fdiscard_desc, genfs_eopnotsupp },       /* fdiscard */
        { &vop_ioctl_desc, fdesc_ioctl },               /* ioctl */
        { &vop_fcntl_desc, genfs_fcntl },               /* fcntl */
        { &vop_poll_desc, fdesc_poll },                 /* poll */
        { &vop_kqfilter_desc, fdesc_kqfilter },         /* kqfilter */
        { &vop_revoke_desc, genfs_revoke },             /* revoke */
        { &vop_mmap_desc, genfs_eopnotsupp },           /* mmap */
        { &vop_fsync_desc, genfs_nullop },              /* fsync */
        { &vop_seek_desc, genfs_seek },                 /* seek */
        { &vop_remove_desc, genfs_eopnotsupp },         /* remove */
        { &vop_link_desc, genfs_erofs_link },           /* link */
        { &vop_rename_desc, genfs_eopnotsupp },         /* rename */
        { &vop_mkdir_desc, genfs_eopnotsupp },          /* mkdir */
        { &vop_rmdir_desc, genfs_eopnotsupp },          /* rmdir */
        { &vop_symlink_desc, genfs_erofs_symlink },     /* symlink */
        { &vop_readdir_desc, fdesc_readdir },           /* readdir */
        { &vop_readlink_desc, fdesc_readlink },         /* readlink */
        { &vop_abortop_desc, genfs_abortop },           /* abortop */
        { &vop_inactive_desc, fdesc_inactive },         /* inactive */
        { &vop_reclaim_desc, fdesc_reclaim },           /* reclaim */
        { &vop_lock_desc, genfs_lock },                 /* lock */
        { &vop_unlock_desc, genfs_unlock },             /* unlock */
        { &vop_bmap_desc, genfs_eopnotsupp },           /* bmap */
        { &vop_strategy_desc, genfs_badop },            /* strategy */
        { &vop_print_desc, fdesc_print },               /* print */
        { &vop_islocked_desc, genfs_islocked },         /* islocked */
        { &vop_pathconf_desc, fdesc_pathconf },         /* pathconf */
        { &vop_advlock_desc, genfs_einval },            /* advlock */
        { &vop_bwrite_desc, genfs_eopnotsupp },         /* bwrite */
        { &vop_putpages_desc, genfs_null_putpages },    /* putpages */
        { NULL, NULL }
};

const struct vnodeopv_desc fdesc_vnodeop_opv_desc =
        { &fdesc_vnodeop_p, fdesc_vnodeop_entries };

/*
 * Initialise cache headers
 */
void
fdesc_init(void)
{
        int cttymajor;

        /* locate the major number */
        cttymajor = devsw_name2chr("ctty", NULL, 0);
        devctty = makedev(cttymajor, 0);
}

void
fdesc_done(void)
{
}

/*
 * vp is the current namei directory
 * ndp is the name to locate in that directory...
 */
int
fdesc_lookup(void *v)
{
        struct vop_lookup_v2_args /* {
                struct vnode * a_dvp;
                struct vnode ** a_vpp;
                struct componentname * a_cnp;
        } */ *ap = v;
        struct vnode **vpp = ap->a_vpp;
        struct vnode *dvp = ap->a_dvp;
        struct componentname *cnp = ap->a_cnp;
        struct lwp *l = curlwp;
        const char *pname = cnp->cn_nameptr;
        struct proc *p = l->l_proc;
        unsigned fd = 0;
        int error, ix = -1;
        fdtab_t *dt;

        dt = atomic_load_consume(&curlwp->l_fd->fd_dt);

        if (cnp->cn_namelen == 1 && *pname == '.') {
                *vpp = dvp;
                vref(dvp);
                return (0);
        }

        switch (VTOFDESC(dvp)->fd_type) {
        default:
        case Flink:
        case Fdesc:
        case Fctty:
                error = ENOTDIR;
                goto bad;

        case Froot:
                if (cnp->cn_namelen == 2 && memcmp(pname, "fd", 2) == 0) {
                        ix = FD_DEVFD;
                        goto good;
                }

                if (cnp->cn_namelen == 3 && memcmp(pname, "tty", 3) == 0) {
                        struct vnode *ttyvp = cttyvp(p);
                        if (ttyvp == NULL) {
                                error = ENXIO;
                                goto bad;
                        }
                        ix = FD_CTTY;
                        goto good;
                }

                switch (cnp->cn_namelen) {
                case 5:
                        if (memcmp(pname, "stdin", 5) == 0) {
                                ix = FD_STDIN;
                                goto good;
                        }
                        break;
                case 6:
                        if (memcmp(pname, "stdout", 6) == 0) {
                                ix = FD_STDOUT;
                                goto good;
                        } else if (memcmp(pname, "stderr", 6) == 0) {
                                ix = FD_STDERR;
                                goto good;
                        }
                        break;
                }

                error = ENOENT;
                goto bad;

        case Fdevfd:
                if (cnp->cn_namelen == 2 && memcmp(pname, "..", 2) == 0) {
                        ix = FD_ROOT;
                        goto good;
                }

                fd = 0;
                while (*pname >= '0' && *pname <= '9') {
                        fd = 10 * fd + *pname++ - '0';
                        if (fd >= dt->dt_nfiles)
                                break;
                }

                if (*pname != '\0') {
                        error = ENOENT;
                        goto bad;
                }

                if (fd >= dt->dt_nfiles || dt->dt_ff[fd] == NULL ||
                    dt->dt_ff[fd]->ff_file == NULL) {
                        error = EBADF;
                        goto bad;
                }

                ix = FD_DESC + fd;
                goto good;
        }

bad:
        *vpp = NULL;
        return error;

good:
        KASSERT(ix != -1);
        error = vcache_get(dvp->v_mount, &ix, sizeof(ix), vpp);
        if (error)
                return error;

        /*
         * Prevent returning VNON nodes.
         * Operation fdesc_inactive() will reset the type to VNON.
         */
        if (ix == FD_CTTY)
                (*vpp)->v_type = VCHR;
        else if (ix >= FD_DESC)
                (*vpp)->v_type = VREG;
        KASSERT((*vpp)->v_type != VNON);

        return 0;
}

int
fdesc_open(void *v)
{
        struct vop_open_args /* {
                struct vnode *a_vp;
                int  a_mode;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;

        switch (VTOFDESC(vp)->fd_type) {
        case Fdesc:
                /*
                 * XXX Kludge: set dupfd to contain the value of the
                 * the file descriptor being sought for duplication.
                 * The error return ensures that the vnode for this
                 * device will be released by vn_open. vn_open will
                 * then detect this special error and take the actions
                 * in fd_dupopen. Other callers of vn_open or VOP_OPEN
                 * not prepared to deal with this situation will
                 * report a real error.
                 */
                curlwp->l_dupfd = VTOFDESC(vp)->fd_fd;  /* XXX */
                return EDUPFD;

        case Fctty:
                return cdev_open(devctty, ap->a_mode, 0, curlwp);
        case Froot:
        case Fdevfd:
        case Flink:
                break;
        }

        return (0);
}

static int
fdesc_attr(int fd, struct vattr *vap, kauth_cred_t cred)
{
        file_t *fp;
        struct stat stb;
        int error;

        if ((fp = fd_getfile(fd)) == NULL)
                return (EBADF);

        switch (fp->f_type) {
        case DTYPE_VNODE:
                vn_lock(fp->f_vnode, LK_SHARED | LK_RETRY);
                error = VOP_GETATTR(fp->f_vnode, vap, cred);
                VOP_UNLOCK(fp->f_vnode);
                if (error == 0 && vap->va_type == VDIR) {
                        /*
                         * directories can cause loops in the namespace,
                         * so turn off the 'x' bits to avoid trouble.
                         */
                        vap->va_mode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
                }
                break;

        default:
                memset(&stb, 0, sizeof(stb));
                error = (*fp->f_ops->fo_stat)(fp, &stb);
                if (error)
                        break;

                vattr_null(vap);
                switch(fp->f_type) {
                case DTYPE_SOCKET:
                        vap->va_type = VSOCK;
                        break;
                case DTYPE_PIPE:
                        vap->va_type = VFIFO;
                        break;
                default:
                        /* use VNON perhaps? */
                        vap->va_type = VBAD;
                        break;
                }
                vap->va_mode = stb.st_mode;
                vap->va_nlink = stb.st_nlink;
                vap->va_uid = stb.st_uid;
                vap->va_gid = stb.st_gid;
                vap->va_fsid = stb.st_dev;
                vap->va_fileid = stb.st_ino;
                vap->va_size = stb.st_size;
                vap->va_blocksize = stb.st_blksize;
                vap->va_atime = stb.st_atimespec;
                vap->va_mtime = stb.st_mtimespec;
                vap->va_ctime = stb.st_ctimespec;
                vap->va_gen = stb.st_gen;
                vap->va_flags = stb.st_flags;
                vap->va_rdev = stb.st_rdev;
                vap->va_bytes = stb.st_blocks * stb.st_blksize;
                break;
        }

        fd_putfile(fd);
        return (error);
}

int
fdesc_getattr(void *v)
{
        struct vop_getattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                kauth_cred_t a_cred;
                struct lwp *a_l;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct vattr *vap = ap->a_vap;
        unsigned fd;
        int error = 0;
        struct timeval tv;

        switch (VTOFDESC(vp)->fd_type) {
        case Froot:
        case Fdevfd:
        case Flink:
        case Fctty:
                vattr_null(vap);
                vap->va_fileid = VTOFDESC(vp)->fd_ix;

#define R_ALL (S_IRUSR|S_IRGRP|S_IROTH)
#define W_ALL (S_IWUSR|S_IWGRP|S_IWOTH)
#define X_ALL (S_IXUSR|S_IXGRP|S_IXOTH)

                switch (VTOFDESC(vp)->fd_type) {
                case Flink:
                        vap->va_mode = R_ALL|X_ALL;
                        vap->va_type = VLNK;
                        vap->va_rdev = 0;
                        vap->va_nlink = 1;
                        vap->va_size = strlen(VTOFDESC(vp)->fd_link);
                        break;

                case Fctty:
                        vap->va_mode = R_ALL|W_ALL;
                        vap->va_type = VCHR;
                        vap->va_rdev = devctty;
                        vap->va_nlink = 1;
                        vap->va_size = 0;
                        break;

                default:
                        vap->va_mode = R_ALL|X_ALL;
                        vap->va_type = VDIR;
                        vap->va_rdev = 0;
                        vap->va_nlink = 2;
                        vap->va_size = DEV_BSIZE;
                        break;
                }
                vap->va_uid = 0;
                vap->va_gid = 0;
                vap->va_fsid = vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0];
                vap->va_blocksize = DEV_BSIZE;
                getmicroboottime(&tv);
                vap->va_atime.tv_sec = tv.tv_sec;
                vap->va_atime.tv_nsec = 0;
                vap->va_mtime = vap->va_atime;
                vap->va_ctime = vap->va_mtime;
                vap->va_gen = 0;
                vap->va_flags = 0;
                vap->va_bytes = 0;
                break;

        case Fdesc:
                fd = VTOFDESC(vp)->fd_fd;
                error = fdesc_attr(fd, vap, ap->a_cred);
                break;

        default:
                panic("fdesc_getattr");
                break;
        }

        if (error == 0)
                vp->v_type = vap->va_type;

        return (error);
}

int
fdesc_setattr(void *v)
{
        struct vop_setattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                kauth_cred_t a_cred;
        } */ *ap = v;
        file_t *fp;
        unsigned fd;

        /*
         * Can't mess with the root vnode
         */
        switch (VTOFDESC(ap->a_vp)->fd_type) {
        case Fdesc:
                break;

        case Fctty:
                return (0);

        default:
                return (EACCES);
        }

        fd = VTOFDESC(ap->a_vp)->fd_fd;
        if ((fp = fd_getfile(fd)) == NULL)
                return (EBADF);

        /*
         * XXX: Can't reasonably set the attr's on any types currently.
         *      On vnode's this will cause truncation and socket/pipes make
         *      no sense.
         */
        fd_putfile(fd);
        return (0);
}


struct fdesc_target {
        ino_t ft_fileno;
        u_char ft_type;
        u_char ft_namlen;
        const char *ft_name;
} fdesc_targets[] = {
#define N(s) sizeof(s)-1, s
        { FD_DEVFD,  DT_DIR,     N("fd")     },
        { FD_STDIN,  DT_LNK,     N("stdin")  },
        { FD_STDOUT, DT_LNK,     N("stdout") },
        { FD_STDERR, DT_LNK,     N("stderr") },
        { FD_CTTY,   DT_UNKNOWN, N("tty")    },
#undef N
#define UIO_MX _DIRENT_RECLEN((struct dirent *)NULL, sizeof("stderr") - 1)
};
static int nfdesc_targets = sizeof(fdesc_targets) / sizeof(fdesc_targets[0]);

int
fdesc_readdir(void *v)
{
        struct vop_readdir_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                kauth_cred_t a_cred;
                int *a_eofflag;
                off_t **a_cookies;
                int *a_ncookies;
        } */ *ap = v;
        struct uio *uio = ap->a_uio;
        struct dirent d;
        off_t i;
        int j;
        int error;
        off_t *cookies = NULL;
        int ncookies;
        fdtab_t *dt;

        switch (VTOFDESC(ap->a_vp)->fd_type) {
        case Fctty:
                return 0;

        case Fdesc:
                return ENOTDIR;

        default:
                break;
        }

        dt = atomic_load_consume(&curlwp->l_fd->fd_dt);

        if (uio->uio_resid < UIO_MX)
                return EINVAL;
        if (uio->uio_offset < 0)
                return EINVAL;

        error = 0;
        i = uio->uio_offset;
        (void)memset(&d, 0, UIO_MX);
        d.d_reclen = UIO_MX;
        if (ap->a_ncookies)
                ncookies = uio->uio_resid / UIO_MX;
        else
                ncookies = 0;

        if (VTOFDESC(ap->a_vp)->fd_type == Froot) {
                struct fdesc_target *ft;

                if (i >= nfdesc_targets)
                        return 0;

                if (ap->a_ncookies) {
                        ncookies = uimin(ncookies, (nfdesc_targets - i));
                        cookies = malloc(ncookies * sizeof(off_t),
                            M_TEMP, M_WAITOK);
                        *ap->a_cookies = cookies;
                        *ap->a_ncookies = ncookies;
                }

                for (ft = &fdesc_targets[i]; uio->uio_resid >= UIO_MX &&
                    i < nfdesc_targets; ft++, i++) {
                        switch (ft->ft_fileno) {
                        case FD_CTTY:
                                if (cttyvp(curproc) == NULL)
                                        continue;
                                break;

                        case FD_STDIN:
                        case FD_STDOUT:
                        case FD_STDERR:
                                if ((ft->ft_fileno - FD_STDIN) >=
                                    dt->dt_nfiles)
                                        continue;
                                if (dt->dt_ff[ft->ft_fileno - FD_STDIN]
                                    == NULL || dt->dt_ff[ft->ft_fileno -
                                    FD_STDIN]->ff_file == NULL)
                                        continue;
                                break;
                        }

                        d.d_fileno = ft->ft_fileno;
                        d.d_namlen = ft->ft_namlen;
                        (void)memcpy(d.d_name, ft->ft_name, ft->ft_namlen + 1);
                        d.d_type = ft->ft_type;

                        if ((error = uiomove(&d, UIO_MX, uio)) != 0)
                                break;
                        if (cookies)
                                *cookies++ = i + 1;
                }
        } else {
                if (ap->a_ncookies) {
                        ncookies = uimin(ncookies, dt->dt_nfiles + 2);
                        cookies = malloc(ncookies * sizeof(off_t),
                            M_TEMP, M_WAITOK);
                        *ap->a_cookies = cookies;
                        *ap->a_ncookies = ncookies;
                }
                for (; i - 2 < dt->dt_nfiles && uio->uio_resid >= UIO_MX; i++) {
                        switch (i) {
                        case 0:
                        case 1:
                                d.d_fileno = FD_ROOT;           /* XXX */
                                d.d_namlen = i + 1;
                                (void)memcpy(d.d_name, "..", d.d_namlen);
                                d.d_name[i + 1] = '\0';
                                d.d_type = DT_DIR;
                                break;

                        default:
                                j = (int)i - 2;
                                if (dt->dt_ff[j] == NULL ||
                                    dt->dt_ff[j]->ff_file == NULL)
                                        continue;
                                d.d_fileno = j + FD_STDIN;
                                d.d_namlen = snprintf(d.d_name,
                                    sizeof(d.d_name), "%d", j);
                                d.d_type = DT_UNKNOWN;
                                break;
                        }

                        if ((error = uiomove(&d, UIO_MX, uio)) != 0)
                                break;
                        if (cookies)
                                *cookies++ = i + 1;
                }
        }

        if (ap->a_ncookies && error) {
                free(*ap->a_cookies, M_TEMP);
                *ap->a_ncookies = 0;
                *ap->a_cookies = NULL;
        }

        uio->uio_offset = i;
        return error;
}

int
fdesc_readlink(void *v)
{
        struct vop_readlink_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        int error;

        if (vp->v_type != VLNK)
                return (EPERM);

        if (VTOFDESC(vp)->fd_type == Flink) {
                const char *ln = VTOFDESC(vp)->fd_link;
                error = uiomove(__UNCONST(ln), strlen(ln), ap->a_uio);
        } else {
                error = EOPNOTSUPP;
        }

        return (error);
}

int
fdesc_read(void *v)
{
        struct vop_read_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int  a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        int error = EOPNOTSUPP;
        struct vnode *vp = ap->a_vp;

        switch (VTOFDESC(vp)->fd_type) {
        case Fctty:
                VOP_UNLOCK(vp);
                error = cdev_read(devctty, ap->a_uio, ap->a_ioflag);
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

int
fdesc_write(void *v)
{
        struct vop_write_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int  a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        int error = EOPNOTSUPP;
        struct vnode *vp = ap->a_vp;

        switch (VTOFDESC(vp)->fd_type) {
        case Fctty:
                VOP_UNLOCK(vp);
                error = cdev_write(devctty, ap->a_uio, ap->a_ioflag);
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

int
fdesc_ioctl(void *v)
{
        struct vop_ioctl_args /* {
                struct vnode *a_vp;
                u_long a_command;
                void *a_data;
                int  a_fflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        int error = EOPNOTSUPP;

        switch (VTOFDESC(ap->a_vp)->fd_type) {
        case Fctty:
                error = cdev_ioctl(devctty, ap->a_command, ap->a_data,
                    ap->a_fflag, curlwp);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

int
fdesc_poll(void *v)
{
        struct vop_poll_args /* {
                struct vnode *a_vp;
                int a_events;
        } */ *ap = v;
        int revents;

        switch (VTOFDESC(ap->a_vp)->fd_type) {
        case Fctty:
                revents = cdev_poll(devctty, ap->a_events, curlwp);
                break;

        default:
                revents = genfs_poll(v);
                break;
        }

        return (revents);
}

int
fdesc_kqfilter(void *v)
{
        struct vop_kqfilter_args /* {
                struct vnode *a_vp;
                struct knote *a_kn;
        } */ *ap = v;
        int error, fd;
        file_t *fp;

        switch (VTOFDESC(ap->a_vp)->fd_type) {
        case Fctty:
                error = cdev_kqfilter(devctty, ap->a_kn);
                break;

        case Fdesc:
                /* just invoke kqfilter for the underlying descriptor */
                fd = VTOFDESC(ap->a_vp)->fd_fd;
                if ((fp = fd_getfile(fd)) == NULL)
                        return (1);
                error = (*fp->f_ops->fo_kqfilter)(fp, ap->a_kn);
                fd_putfile(fd);
                break;

        default:
                return (genfs_kqfilter(v));
        }

        return (error);
}

int
fdesc_inactive(void *v)
{
        struct vop_inactive_v2_args /* {
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct fdescnode *fd = VTOFDESC(vp);

        /*
         * Clear out the v_type field to avoid
         * nasty things happening on reclaim.
         */
        if (fd->fd_type == Fctty || fd->fd_type == Fdesc)
                vp->v_type = VNON;

        return (0);
}

int
fdesc_reclaim(void *v)
{
        struct vop_reclaim_v2_args /* {
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct fdescnode *fd = VTOFDESC(vp);

        VOP_UNLOCK(vp);

        vp->v_data = NULL;
        kmem_free(fd, sizeof(struct fdescnode));

        return (0);
}

/*
 * Return POSIX pathconf information applicable to special devices.
 */
int
fdesc_pathconf(void *v)
{
        struct vop_pathconf_args /* {
                struct vnode *a_vp;
                int a_name;
                register_t *a_retval;
        } */ *ap = v;

        switch (ap->a_name) {
        case _PC_LINK_MAX:
                *ap->a_retval = LINK_MAX;
                return (0);
        case _PC_MAX_CANON:
                *ap->a_retval = MAX_CANON;
                return (0);
        case _PC_MAX_INPUT:
                *ap->a_retval = MAX_INPUT;
                return (0);
        case _PC_PIPE_BUF:
                *ap->a_retval = PIPE_BUF;
                return (0);
        case _PC_CHOWN_RESTRICTED:
                *ap->a_retval = 1;
                return (0);
        case _PC_VDISABLE:
                *ap->a_retval = _POSIX_VDISABLE;
                return (0);
        case _PC_SYNC_IO:
                *ap->a_retval = 1;
                return (0);
        default:
                return genfs_pathconf(ap);
        }
        /* NOTREACHED */
}

/*
 * Print out the contents of a /dev/fd vnode.
 */
/* ARGSUSED */
int
fdesc_print(void *v)
{
        printf("tag VT_NON, fdesc vnode\n");
        return (0);
}