/*
 * Copyright (c) 1990, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * Filesystem FIFO type ops.  All entry points are MPSAFE.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/unistd.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/event.h>
#include <sys/un.h>

#include <sys/socketvar2.h>

#include "fifo.h"

/*
 * This structure is associated with the FIFO vnode and stores
 * the state associated with the FIFO.
 */
struct fifoinfo {
        struct socket   *fi_readsock;
        struct socket   *fi_writesock;
        long            fi_readers;
        long            fi_writers;
};

#define FIFO_LOCK_POOL  128
#define FIFO_LOCK_MASK  (FIFO_LOCK_POOL - 1)

static int      fifo_badop (void);
static int      fifo_print (struct vop_print_args *);
static int      fifo_lookup (struct vop_old_lookup_args *);
static int      fifo_open (struct vop_open_args *);
static int      fifo_close (struct vop_close_args *);
static int      fifo_read (struct vop_read_args *);
static int      fifo_write (struct vop_write_args *);
static int      fifo_ioctl (struct vop_ioctl_args *);
static int      fifo_kqfilter (struct vop_kqfilter_args *);
static int      fifo_inactive (struct  vop_inactive_args *);
static int      fifo_bmap (struct vop_bmap_args *);
static int      fifo_pathconf (struct vop_pathconf_args *);
static int      fifo_advlock (struct vop_advlock_args *);

static void     filt_fifordetach(struct knote *kn);
static int      filt_fiforead(struct knote *kn, long hint);
static void     filt_fifowdetach(struct knote *kn);
static int      filt_fifowrite(struct knote *kn, long hint);

static struct filterops fiforead_filtops =
        { FILTEROP_ISFD, NULL, filt_fifordetach, filt_fiforead };
static struct filterops fifowrite_filtops =
        { FILTEROP_ISFD, NULL, filt_fifowdetach, filt_fifowrite };

struct vop_ops fifo_vnode_vops = {
        .vop_default =          vop_defaultop,
        .vop_access =           (void *)vop_ebadf,
        .vop_advlock =          fifo_advlock,
        .vop_bmap =             fifo_bmap,
        .vop_close =            fifo_close,
        .vop_old_create =       (void *)fifo_badop,
        .vop_getattr =          (void *)vop_ebadf,
        .vop_inactive =         fifo_inactive,
        .vop_ioctl =            fifo_ioctl,
        .vop_kqfilter =         fifo_kqfilter,
        .vop_old_link =         (void *)fifo_badop,
        .vop_old_lookup =       fifo_lookup,
        .vop_old_mkdir =        (void *)fifo_badop,
        .vop_old_mknod =        (void *)fifo_badop,
        .vop_open =             fifo_open,
        .vop_pathconf =         fifo_pathconf,
        .vop_print =            fifo_print,
        .vop_read =             fifo_read,
        .vop_readdir =          (void *)fifo_badop,
        .vop_readlink =         (void *)fifo_badop,
        .vop_reallocblks =      (void *)fifo_badop,
        .vop_reclaim =          (void *)vop_null,
        .vop_old_remove =       (void *)fifo_badop,
        .vop_old_rename =       (void *)fifo_badop,
        .vop_old_rmdir =        (void *)fifo_badop,
        .vop_setattr =          (void *)vop_ebadf,
        .vop_old_symlink =      (void *)fifo_badop,
        .vop_write =            fifo_write
};

VNODEOP_SET(fifo_vnode_vops);

static MALLOC_DEFINE(M_FIFOINFO, "Fifo info", "Fifo info entries");

/*
 * The vnode might be using a shared lock, we need an exclusive lock
 * for open/close sequencing.  Create a little pool of locks.
 */
static struct lock fifo_locks[FIFO_LOCK_POOL];

static __inline
void
fifo_lock(struct vnode *vp)
{
        int hv;

        hv = ((intptr_t)vp / sizeof(*vp)) & FIFO_LOCK_MASK;
        lockmgr(&fifo_locks[hv], LK_EXCLUSIVE);
}

static __inline
void
fifo_unlock(struct vnode *vp)
{
        int hv;

        hv = ((intptr_t)vp / sizeof(*vp)) & FIFO_LOCK_MASK;
        lockmgr(&fifo_locks[hv], LK_RELEASE);
}

static void
fifo_init(void)
{
        int i;

        for (i = 0; i < FIFO_LOCK_POOL; ++i)
                lockinit(&fifo_locks[i], "fifolk", 0, 0);
}
SYSINIT(fifoinit, SI_SUB_PSEUDO, SI_ORDER_ANY, fifo_init, NULL);

/*
 * fifo_vnoperate()
 */
int
fifo_vnoperate(struct vop_generic_args *ap)
{
        return (VOCALL(&fifo_vnode_vops, ap));
}

/*
 * Trivial lookup routine that always fails.
 *
 * fifo_lookup(struct vnode *a_dvp, struct vnode **a_vpp,
 *             struct componentname *a_cnp)
 */
/* ARGSUSED */
static int
fifo_lookup(struct vop_old_lookup_args *ap)
{
        *ap->a_vpp = NULL;
        return (ENOTDIR);
}

/*
 * Create/destroy the socket pairs for the fifo
 */
static
struct fifoinfo *
fifo_fip_create(int *errorp)
{
        struct thread *td = curthread;
        struct fifoinfo *fip;
        struct socket *rso, *wso;

        fip = kmalloc(sizeof(*fip), M_FIFOINFO, M_WAITOK);
        *errorp = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, td);
        if (*errorp) {
                kfree(fip, M_FIFOINFO);
                return NULL;
        }
        rso->so_options &= ~SO_LINGER;
        fip->fi_readsock = rso;
        *errorp = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, td);
        if (*errorp) {
                soclose(rso, FNONBLOCK);
                kfree(fip, M_FIFOINFO);
                return NULL;
        }
        wso->so_options &= ~SO_LINGER;
        fip->fi_writesock = wso;
        *errorp = unp_connect2(wso, rso, td->td_ucred);
        if (*errorp) {
                soclose(wso, FNONBLOCK);
                soclose(rso, FNONBLOCK);
                kfree(fip, M_FIFOINFO);
                return NULL;
        }
        fip->fi_readers = fip->fi_writers = 0;
        wso->so_snd.ssb_lowat = PIPE_BUF;
        sosetstate(rso, SS_CANTRCVMORE);

        return fip;
}

static int
fifo_fip_destroy(struct fifoinfo *fip)
{
        int error1, error;

        error1 = soclose(fip->fi_readsock, FNONBLOCK);
        error = soclose(fip->fi_writesock, FNONBLOCK);
        kfree(fip, M_FIFOINFO);
        if (error1)
                error = error1;
        return error;
}

/*
 * Open called to set up a new instance of a fifo or
 * to find an active instance of a fifo.
 *
 * fifo_open(struct vnode *a_vp, int a_mode, struct ucred *a_cred,
 *           struct file *a_fp)
 */
/* ARGSUSED */
static int
fifo_open(struct vop_open_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct fifoinfo *fip;
        int error;

        error = 0;

        /*
         * Create the fip if necessary
         */
        fifo_lock(vp);
        if ((fip = vp->v_fifoinfo) == NULL) {
                fip = fifo_fip_create(&error);
                if (fip == NULL) {
                        fifo_unlock(vp);
                        return error;
                }
                vp->v_fifoinfo = fip;
        }

        /*
         * Adjust fi_readers and fi_writers interlocked and issue wakeups
         * as appropriate.
         */
        if (ap->a_mode & FREAD) {
                fip->fi_readers++;
                if (fip->fi_readers == 1) {
                        soisreconnected(fip->fi_writesock);
                        if (fip->fi_writers > 0) {
                                wakeup((caddr_t)&fip->fi_writers);
                                sowwakeup(fip->fi_writesock);
                        }
                }
        }
        if (ap->a_mode & FWRITE) {
                fip->fi_writers++;
                if (fip->fi_writers == 1) {
                        soisreconnected(fip->fi_readsock);
                        if (fip->fi_readers > 0) {
                                wakeup((caddr_t)&fip->fi_readers);
                                sorwakeup(fip->fi_writesock);
                        }
                }
        }

        /*
         * Handle blocking as appropriate
         */
        if ((ap->a_mode & FREAD) && (ap->a_mode & O_NONBLOCK) == 0) {
                if (fip->fi_writers == 0) {
                        fifo_unlock(vp);
                        vn_unlock(vp);
                        error = tsleep((caddr_t)&fip->fi_readers,
                                       PCATCH, "fifoor", 0);
                        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                        fifo_lock(vp);
                        if (error)
                                goto bad;
                        /*
                         * We must have got woken up because we had a writer.
                         * That (and not still having one) is the condition
                         * that we must wait for.
                         */
                }
        }
        if (ap->a_mode & FWRITE) {
                if (ap->a_mode & O_NONBLOCK) {
                        if (fip->fi_readers == 0) {
                                error = ENXIO;
                                goto bad;
                        }
                } else {
                        if (fip->fi_readers == 0) {
                                fifo_unlock(vp);
                                vn_unlock(vp);
                                error = tsleep((caddr_t)&fip->fi_writers,
                                               PCATCH, "fifoow", 0);
                                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                                fifo_lock(vp);
                                if (error)
                                        goto bad;
                                /*
                                 * We must have got woken up because we had
                                 * a reader.  That (and not still having one)
                                 * is the condition that we must wait for.
                                 */
                        }
                }
        }
        vsetflags(vp, VNOTSEEKABLE);
        error = vop_stdopen(ap);
        fifo_unlock(vp);

        return (error);

bad:
        if (ap->a_mode & FREAD) {
                fip->fi_readers--;
                if (fip->fi_readers == 0)
                        soisdisconnected(fip->fi_writesock);
        }
        if (ap->a_mode & FWRITE) {
                fip->fi_writers--;
                if (fip->fi_writers == 0)
                        soisdisconnected(fip->fi_readsock);
        }
        if (fip->fi_readers == 0 && fip->fi_writers == 0) {
                vp->v_fifoinfo = NULL;
                (void)fifo_fip_destroy(fip);
        }
        fifo_unlock(vp);

        return (error);
}

/*
 * Vnode op for read
 *
 * fifo_read(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 *           struct ucred *a_cred)
 */
/* ARGSUSED */
static int
fifo_read(struct vop_read_args *ap)
{
        struct uio *uio = ap->a_uio;
        struct vnode *vp = ap->a_vp;
        struct socket *rso = vp->v_fifoinfo->fi_readsock;
        int error;
        int flags;

#ifdef DIAGNOSTIC
        if (uio->uio_rw != UIO_READ)
                panic("fifo_read mode");
#endif
        if (uio->uio_resid == 0)
                return (0);
        if (ap->a_ioflag & IO_NDELAY)
                flags = MSG_FNONBLOCKING;
        else
                flags = 0;
        vn_unlock(vp);
        lwkt_gettoken(&vp->v_token);
        error = soreceive(rso, NULL, uio, NULL, NULL, &flags);
        lwkt_reltoken(&vp->v_token);
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        return (error);
}

/*
 * Vnode op for write
 *
 * fifo_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 *            struct ucred *a_cred)
 */
/* ARGSUSED */
static int
fifo_write(struct vop_write_args *ap)
{
        struct thread *td = ap->a_uio->uio_td;
        struct vnode *vp = ap->a_vp;
        struct socket *wso = vp->v_fifoinfo->fi_writesock;
        int error;
        int flags;

#ifdef DIAGNOSTIC
        if (ap->a_uio->uio_rw != UIO_WRITE)
                panic("fifo_write mode");
#endif
        if (ap->a_ioflag & IO_NDELAY)
                flags = MSG_FNONBLOCKING;
        else
                flags = 0;
        vn_unlock(vp);
        lwkt_gettoken(&vp->v_token);
        error = sosend(wso, NULL, ap->a_uio, 0, NULL, flags, td);
        lwkt_reltoken(&vp->v_token);
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        return (error);
}

/*
 * Device ioctl operation.
 *
 * fifo_ioctl(struct vnode *a_vp, int a_command, caddr_t a_data, int a_fflag,
 *            struct ucred *a_cred, struct sysmsg *a_sysmsg)
 */
/* ARGSUSED */
static int
fifo_ioctl(struct vop_ioctl_args *ap)
{
        struct file filetmp;    /* Local */
        struct vnode *vp = ap->a_vp;
        int error;

        if (ap->a_fflag & FREAD) {
                filetmp.f_data = vp->v_fifoinfo->fi_readsock;
                lwkt_gettoken(&vp->v_token);
                error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
                                  ap->a_cred, ap->a_sysmsg);
                lwkt_reltoken(&vp->v_token);
                if (error)
                        return (error);
        }
        if (ap->a_fflag & FWRITE) {
                filetmp.f_data = vp->v_fifoinfo->fi_writesock;
                lwkt_gettoken(&vp->v_token);
                error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
                                  ap->a_cred, ap->a_sysmsg);
                lwkt_reltoken(&vp->v_token);
                if (error)
                        return (error);
        }
        return (0);
}

/*
 * fifo_kqfilter(struct vnode *a_vp, struct knote *a_kn)
 */
/* ARGSUSED */
static int
fifo_kqfilter(struct vop_kqfilter_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct fifoinfo *fi = vp->v_fifoinfo;
        struct socket *so;
        struct signalsockbuf *ssb;

        lwkt_gettoken(&vp->v_token);

        switch (ap->a_kn->kn_filter) {
        case EVFILT_READ:
                ap->a_kn->kn_fop = &fiforead_filtops;
                so = fi->fi_readsock;
                ssb = &so->so_rcv;
                break;
        case EVFILT_WRITE:
                ap->a_kn->kn_fop = &fifowrite_filtops;
                so = fi->fi_writesock;
                ssb = &so->so_snd;
                break;
        default:
                lwkt_reltoken(&vp->v_token);
                return (EOPNOTSUPP);
        }

        ap->a_kn->kn_hook = (caddr_t)vp;
        ssb_insert_knote(ssb, ap->a_kn);

        lwkt_reltoken(&vp->v_token);
        return (0);
}

static void
filt_fifordetach(struct knote *kn)
{
        struct vnode *vp = (void *)kn->kn_hook;
        struct socket *so = vp->v_fifoinfo->fi_readsock;

        lwkt_gettoken(&vp->v_token);
        ssb_remove_knote(&so->so_rcv, kn);
        lwkt_reltoken(&vp->v_token);
}

static int
filt_fiforead(struct knote *kn, long hint)
{
        struct vnode *vp = (void *)kn->kn_hook;
        struct socket *so = vp->v_fifoinfo->fi_readsock;

        lwkt_gettoken(&vp->v_token);
        kn->kn_data = so->so_rcv.ssb_cc;
        if ((kn->kn_sfflags & NOTE_OLDAPI) == 0 &&
            so->so_state & SS_ISDISCONNECTED) {
                if (kn->kn_data == 0)
                        kn->kn_flags |= EV_NODATA;
                kn->kn_flags |= EV_EOF | EV_HUP;
                lwkt_reltoken(&vp->v_token);
                return (1);
        }
        kn->kn_flags &= ~(EV_EOF | EV_HUP | EV_NODATA);
        lwkt_reltoken(&vp->v_token);
        if ((kn->kn_sfflags & NOTE_HUPONLY) == 0)
                return (kn->kn_data > 0);
        return 0;
}

static void
filt_fifowdetach(struct knote *kn)
{
        struct vnode *vp = (void *)kn->kn_hook;
        struct socket *so = vp->v_fifoinfo->fi_writesock;

        lwkt_gettoken(&vp->v_token);
        ssb_remove_knote(&so->so_snd, kn);
        lwkt_reltoken(&vp->v_token);
}

static int
filt_fifowrite(struct knote *kn, long hint)
{
        struct vnode *vp = (void *)kn->kn_hook;
        struct socket *so = vp->v_fifoinfo->fi_writesock;

        lwkt_gettoken(&vp->v_token);
        kn->kn_data = ssb_space(&so->so_snd);
        if (so->so_state & SS_ISDISCONNECTED) {
                kn->kn_flags |= EV_EOF | EV_HUP | EV_NODATA;
                lwkt_reltoken(&vp->v_token);
                return (1);
        }
        kn->kn_flags &= ~(EV_EOF | EV_HUP | EV_NODATA);
        lwkt_reltoken(&vp->v_token);
        return (kn->kn_data >= so->so_snd.ssb_lowat);
}

/*
 * fifo_inactive(struct vnode *a_vp)
 */
static int
fifo_inactive(struct vop_inactive_args *ap)
{
        return (0);
}

/*
 * This is a noop, simply returning what one has been given.
 *
 * fifo_bmap(struct vnode *a_vp, off_t a_loffset, 
 *           off_t *a_doffsetp, int *a_runp, int *a_runb)
 */
static int
fifo_bmap(struct vop_bmap_args *ap)
{
        if (ap->a_doffsetp != NULL)
                *ap->a_doffsetp = ap->a_loffset;
        if (ap->a_runp != NULL)
                *ap->a_runp = 0;
        if (ap->a_runb != NULL)
                *ap->a_runb = 0;
        return (0);
}

/*
 * Device close routine
 *
 * fifo_close(struct vnode *a_vp, int a_fflag)
 */
/* ARGSUSED */
static int
fifo_close(struct vop_close_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct fifoinfo *fip;
        int error;

        fifo_lock(vp);
        fip = vp->v_fifoinfo;
        if (fip == NULL) {
                vop_stdclose(ap);
                fifo_unlock(vp);
                return 0;
        }
        if (ap->a_fflag & FREAD) {
                fip->fi_readers--;
                if (fip->fi_readers == 0)
                        soisdisconnected(fip->fi_writesock);
        }
        if (ap->a_fflag & FWRITE) {
                fip->fi_writers--;
                if (fip->fi_writers == 0)
                        soisdisconnected(fip->fi_readsock);
        }
        if (fip->fi_readers == 0 && fip->fi_writers == 0) {
                vp->v_fifoinfo = NULL;
                error = fifo_fip_destroy(fip);
        } else {
                error = 0;
        }
        vop_stdclose(ap);
        fifo_unlock(vp);

        return error;
}

/*
 * Print out internal contents of a fifo vnode.
 */
int
fifo_printinfo(struct vnode *vp)
{
        struct fifoinfo *fip = vp->v_fifoinfo;

        kprintf(", fifo with %ld readers and %ld writers",
                fip->fi_readers, fip->fi_writers);
        return (0);
}

/*
 * Print out the contents of a fifo vnode.
 *
 * fifo_print(struct vnode *a_vp)
 */
static int
fifo_print(struct vop_print_args *ap)
{
        kprintf("tag VT_NON");
        fifo_printinfo(ap->a_vp);
        kprintf("\n");
        return (0);
}

/*
 * Return POSIX pathconf information applicable to fifo's.
 *
 * fifo_pathconf(struct vnode *a_vp, int a_name, int *a_retval)
 */
int
fifo_pathconf(struct vop_pathconf_args *ap)
{
        switch (ap->a_name) {
        case _PC_LINK_MAX:
                *ap->a_retval = LINK_MAX;
                return (0);
        case _PC_PIPE_BUF:
                *ap->a_retval = PIPE_BUF;
                return (0);
        case _PC_CHOWN_RESTRICTED:
                *ap->a_retval = 1;
                return (0);
        default:
                return (EINVAL);
        }
        /* NOTREACHED */
}

/*
 * Fifo advisory byte-level locks.
 *
 * fifo_advlock(struct vnode *a_vp, caddr_t a_id, int a_op, struct flock *a_fl,
 *              int a_flags)
 */
/* ARGSUSED */
static int
fifo_advlock(struct vop_advlock_args *ap)
{
        return ((ap->a_flags & F_POSIX) ? EINVAL : EOPNOTSUPP);
}

/*
 * Fifo bad operation
 */
static int
fifo_badop(void)
{
        panic("fifo_badop called");
        /* NOTREACHED */
}