/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 */

#include "opt_capsicum.h"
#include "opt_ktrace.h"

#define EXTERR_CATEGORY EXTERR_CAT_GENIO
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/capsicum.h>
#include <sys/exterrvar.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/inotify.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/protosw.h>
#include <sys/socketvar.h>
#include <sys/uio.h>
#include <sys/eventfd.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/resourcevar.h>
#include <sys/selinfo.h>
#include <sys/sleepqueue.h>
#include <sys/specialfd.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/vnode.h>
#include <sys/unistd.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/condvar.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <security/audit/audit.h>

/*
 * The following macro defines how many bytes will be allocated from
 * the stack instead of memory allocated when passing the IOCTL data
 * structures from userspace and to the kernel. Some IOCTLs having
 * small data structures are used very frequently and this small
 * buffer on the stack gives a significant speedup improvement for
 * those requests. The value of this define should be greater or equal
 * to 64 bytes and should also be power of two. The data structure is
 * currently hard-aligned to a 8-byte boundary on the stack. This
 * should currently be sufficient for all supported platforms.
 */
#define SYS_IOCTL_SMALL_SIZE    128     /* bytes */
#define SYS_IOCTL_SMALL_ALIGN   8       /* bytes */

#ifdef __LP64__
static int iosize_max_clamp = 0;
SYSCTL_INT(_debug, OID_AUTO, iosize_max_clamp, CTLFLAG_RW,
    &iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX");
static int devfs_iosize_max_clamp = 1;
SYSCTL_INT(_debug, OID_AUTO, devfs_iosize_max_clamp, CTLFLAG_RW,
    &devfs_iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX for devices");
#endif

/*
 * Assert that the return value of read(2) and write(2) syscalls fits
 * into a register.  If not, an architecture will need to provide the
 * usermode wrappers to reconstruct the result.
 */
CTASSERT(sizeof(register_t) >= sizeof(size_t));

static MALLOC_DEFINE(M_IOCTLOPS, "ioctlops", "ioctl data buffer");
static MALLOC_DEFINE(M_SELECT, "select", "select() buffer");
MALLOC_DEFINE(M_IOV, "iov", "large iov's");

#ifdef EXTERR_STRINGS
FEATURE(exterr_strings, "Extended error reporting includes message strings");
#endif

static int      pollout(struct thread *, struct pollfd *, struct pollfd *,
                    u_int);
static int      pollscan(struct thread *, struct pollfd *, u_int);
static int      pollrescan(struct thread *);
static int      selscan(struct thread *, fd_mask **, fd_mask **, int);
static int      selrescan(struct thread *, fd_mask **, fd_mask **);
static void     selfdalloc(struct thread *, void *);
static void     selfdfree(struct seltd *, struct selfd *);
static int      dofileread(struct thread *, int, struct file *, struct uio *,
                    off_t, int);
static int      dofilewrite(struct thread *, int, struct file *, struct uio *,
                    off_t, int);
static void     doselwakeup(struct selinfo *, int);
static void     seltdinit(struct thread *);
static int      seltdwait(struct thread *, sbintime_t, sbintime_t);
static void     seltdclear(struct thread *);

/*
 * One seltd per-thread allocated on demand as needed.
 *
 *      t - protected by st_mtx
 *      k - Only accessed by curthread or read-only
 */
struct seltd {
        STAILQ_HEAD(, selfd)    st_selq;        /* (k) List of selfds. */
        struct selfd            *st_free1;      /* (k) free fd for read set. */
        struct selfd            *st_free2;      /* (k) free fd for write set. */
        struct mtx              st_mtx;         /* Protects struct seltd */
        struct cv               st_wait;        /* (t) Wait channel. */
        int                     st_flags;       /* (t) SELTD_ flags. */
};

#define SELTD_PENDING   0x0001                  /* We have pending events. */
#define SELTD_RESCAN    0x0002                  /* Doing a rescan. */

/*
 * One selfd allocated per-thread per-file-descriptor.
 *      f - protected by sf_mtx
 */
struct selfd {
        STAILQ_ENTRY(selfd)     sf_link;        /* (k) fds owned by this td. */
        TAILQ_ENTRY(selfd)      sf_threads;     /* (f) fds on this selinfo. */
        struct selinfo          *sf_si;         /* (f) selinfo when linked. */
        struct mtx              *sf_mtx;        /* Pointer to selinfo mtx. */
        struct seltd            *sf_td;         /* (k) owning seltd. */
        void                    *sf_cookie;     /* (k) fd or pollfd. */
};

MALLOC_DEFINE(M_SELFD, "selfd", "selfd");
static struct mtx_pool *mtxpool_select;

#ifdef __LP64__
size_t
devfs_iosize_max(void)
{

        return (devfs_iosize_max_clamp || SV_CURPROC_FLAG(SV_ILP32) ?
            INT_MAX : SSIZE_MAX);
}

size_t
iosize_max(void)
{

        return (iosize_max_clamp || SV_CURPROC_FLAG(SV_ILP32) ?
            INT_MAX : SSIZE_MAX);
}
#endif

#ifndef _SYS_SYSPROTO_H_
struct read_args {
        int     fd;
        void    *buf;
        size_t  nbyte;
};
#endif
int
sys_read(struct thread *td, struct read_args *uap)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        if (uap->nbyte > IOSIZE_MAX)
                return (EXTERROR(EINVAL, "length > iosize_max"));
        aiov.iov_base = uap->buf;
        aiov.iov_len = uap->nbyte;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = uap->nbyte;
        auio.uio_segflg = UIO_USERSPACE;
        error = kern_readv(td, uap->fd, &auio);
        return (error);
}

/*
 * Positioned read system call
 */
#ifndef _SYS_SYSPROTO_H_
struct pread_args {
        int     fd;
        void    *buf;
        size_t  nbyte;
        int     pad;
        off_t   offset;
};
#endif
int
sys_pread(struct thread *td, struct pread_args *uap)
{

        return (kern_pread(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
}

int
kern_pread(struct thread *td, int fd, void *buf, size_t nbyte, off_t offset)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        if (nbyte > IOSIZE_MAX)
                return (EXTERROR(EINVAL, "length > iosize_max"));
        aiov.iov_base = buf;
        aiov.iov_len = nbyte;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = nbyte;
        auio.uio_segflg = UIO_USERSPACE;
        error = kern_preadv(td, fd, &auio, offset);
        return (error);
}

#if defined(COMPAT_FREEBSD6)
int
freebsd6_pread(struct thread *td, struct freebsd6_pread_args *uap)
{

        return (kern_pread(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
}
#endif

/*
 * Scatter read system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct readv_args {
        int     fd;
        struct  iovec *iovp;
        u_int   iovcnt;
};
#endif
int
sys_readv(struct thread *td, struct readv_args *uap)
{
        struct uio *auio;
        int error;

        error = copyinuio(uap->iovp, uap->iovcnt, &auio);
        if (error)
                return (error);
        error = kern_readv(td, uap->fd, auio);
        freeuio(auio);
        return (error);
}

int
kern_readv(struct thread *td, int fd, struct uio *auio)
{
        struct file *fp;
        int error;

        error = fget_read(td, fd, &cap_read_rights, &fp);
        if (error)
                return (error);
        error = dofileread(td, fd, fp, auio, (off_t)-1, 0);
        fdrop(fp, td);
        return (error);
}

/*
 * Scatter positioned read system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct preadv_args {
        int     fd;
        struct  iovec *iovp;
        u_int   iovcnt;
        off_t   offset;
};
#endif
int
sys_preadv(struct thread *td, struct preadv_args *uap)
{
        struct uio *auio;
        int error;

        error = copyinuio(uap->iovp, uap->iovcnt, &auio);
        if (error)
                return (error);
        error = kern_preadv(td, uap->fd, auio, uap->offset);
        freeuio(auio);
        return (error);
}

int
kern_preadv(struct thread *td, int fd, struct uio *auio, off_t offset)
{
        struct file *fp;
        int error;

        error = fget_read(td, fd, &cap_pread_rights, &fp);
        if (error)
                return (error);
        if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
                error = ESPIPE;
        else if (offset < 0 &&
            (fp->f_vnode == NULL || fp->f_vnode->v_type != VCHR))
                error = EXTERROR(EINVAL, "neg offset");
        else
                error = dofileread(td, fd, fp, auio, offset, FOF_OFFSET);
        fdrop(fp, td);
        return (error);
}

/*
 * Common code for readv and preadv that reads data in
 * from a file using the passed in uio, offset, and flags.
 */
static int
dofileread(struct thread *td, int fd, struct file *fp, struct uio *auio,
    off_t offset, int flags)
{
        ssize_t cnt;
        int error;
#ifdef KTRACE
        struct uio *ktruio = NULL;
#endif

        AUDIT_ARG_FD(fd);

        /* Finish zero length reads right here */
        if (auio->uio_resid == 0) {
                td->td_retval[0] = 0;
                return (0);
        }
        auio->uio_rw = UIO_READ;
        auio->uio_offset = offset;
        auio->uio_td = td;
#ifdef KTRACE
        if (KTRPOINT(td, KTR_GENIO)) 
                ktruio = cloneuio(auio);
#endif
        cnt = auio->uio_resid;
        if ((error = fo_read(fp, auio, td->td_ucred, flags, td))) {
                if (auio->uio_resid != cnt && (error == ERESTART ||
                    error == EINTR || error == EWOULDBLOCK))
                        error = 0;
        }
        cnt -= auio->uio_resid;
#ifdef KTRACE
        if (ktruio != NULL) {
                ktruio->uio_resid = cnt;
                ktrgenio(fd, UIO_READ, ktruio, error);
        }
#endif
        td->td_retval[0] = cnt;
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct write_args {
        int     fd;
        const void *buf;
        size_t  nbyte;
};
#endif
int
sys_write(struct thread *td, struct write_args *uap)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        if (uap->nbyte > IOSIZE_MAX)
                return (EXTERROR(EINVAL, "length > iosize_max"));
        aiov.iov_base = (void *)(uintptr_t)uap->buf;
        aiov.iov_len = uap->nbyte;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = uap->nbyte;
        auio.uio_segflg = UIO_USERSPACE;
        error = kern_writev(td, uap->fd, &auio);
        return (error);
}

/*
 * Positioned write system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct pwrite_args {
        int     fd;
        const void *buf;
        size_t  nbyte;
        int     pad;
        off_t   offset;
};
#endif
int
sys_pwrite(struct thread *td, struct pwrite_args *uap)
{

        return (kern_pwrite(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
}

int
kern_pwrite(struct thread *td, int fd, const void *buf, size_t nbyte,
    off_t offset)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        if (nbyte > IOSIZE_MAX)
                return (EXTERROR(EINVAL, "length > iosize_max"));
        aiov.iov_base = (void *)(uintptr_t)buf;
        aiov.iov_len = nbyte;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = nbyte;
        auio.uio_segflg = UIO_USERSPACE;
        error = kern_pwritev(td, fd, &auio, offset);
        return (error);
}

#if defined(COMPAT_FREEBSD6)
int
freebsd6_pwrite(struct thread *td, struct freebsd6_pwrite_args *uap)
{

        return (kern_pwrite(td, uap->fd, uap->buf, uap->nbyte, uap->offset));
}
#endif

/*
 * Gather write system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct writev_args {
        int     fd;
        struct  iovec *iovp;
        u_int   iovcnt;
};
#endif
int
sys_writev(struct thread *td, struct writev_args *uap)
{
        struct uio *auio;
        int error;

        error = copyinuio(uap->iovp, uap->iovcnt, &auio);
        if (error)
                return (error);
        error = kern_writev(td, uap->fd, auio);
        freeuio(auio);
        return (error);
}

int
kern_writev(struct thread *td, int fd, struct uio *auio)
{
        struct file *fp;
        int error;

        error = fget_write(td, fd, &cap_write_rights, &fp);
        if (error)
                return (error);
        error = dofilewrite(td, fd, fp, auio, (off_t)-1, 0);
        fdrop(fp, td);
        return (error);
}

/*
 * Gather positioned write system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct pwritev_args {
        int     fd;
        struct  iovec *iovp;
        u_int   iovcnt;
        off_t   offset;
};
#endif
int
sys_pwritev(struct thread *td, struct pwritev_args *uap)
{
        struct uio *auio;
        int error;

        error = copyinuio(uap->iovp, uap->iovcnt, &auio);
        if (error)
                return (error);
        error = kern_pwritev(td, uap->fd, auio, uap->offset);
        freeuio(auio);
        return (error);
}

int
kern_pwritev(struct thread *td, int fd, struct uio *auio, off_t offset)
{
        struct file *fp;
        int error;

        error = fget_write(td, fd, &cap_pwrite_rights, &fp);
        if (error)
                return (error);
        if (!(fp->f_ops->fo_flags & DFLAG_SEEKABLE))
                error = ESPIPE;
        else if (offset < 0 &&
            (fp->f_vnode == NULL || fp->f_vnode->v_type != VCHR))
                error = EXTERROR(EINVAL, "neg offset");
        else
                error = dofilewrite(td, fd, fp, auio, offset, FOF_OFFSET);
        fdrop(fp, td);
        return (error);
}

/*
 * Common code for writev and pwritev that writes data to
 * a file using the passed in uio, offset, and flags.
 */
static int
dofilewrite(struct thread *td, int fd, struct file *fp, struct uio *auio,
    off_t offset, int flags)
{
        ssize_t cnt;
        int error;

        AUDIT_ARG_FD(fd);

        auio->uio_rw = UIO_WRITE;
        auio->uio_td = td;
        auio->uio_offset = offset;
        error = kern_filewrite(td, fd, fp, auio, flags, &cnt);

        /*
         * Handle short writes and generate SIGPIPE if needed.
         * Socket layer is responsible for special error handling,
         * see sousrsend().
         */
        if (error != 0 && fp->f_type != DTYPE_SOCKET) {
                if (cnt != 0 && (error == ERESTART ||
                    error == EINTR || error == EWOULDBLOCK))
                        error = 0;
                if (error == EPIPE) {
                        PROC_LOCK(td->td_proc);
                        tdsignal(td, SIGPIPE);
                        PROC_UNLOCK(td->td_proc);
                }
        }

        if (error == 0)
                td->td_retval[0] = cnt;
        return (error);
}

/*
 * Write io request specified by auio into the file fp.  If fd != -1,
 * might generate the ktrace io point.
 */
int
kern_filewrite(struct thread *td, int fd, struct file *fp, struct uio *auio,
    int flags, ssize_t *cntp)
{
        ssize_t cnt;
        int error;
#ifdef KTRACE
        struct uio *ktruio;

        ktruio = fd != -1 && KTRPOINT(td, KTR_GENIO) ? cloneuio(auio) : NULL;
#endif
        cnt = auio->uio_resid;
        error = fo_write(fp, auio, td->td_ucred, flags, td);
        cnt -= auio->uio_resid;
#ifdef KTRACE
        if (ktruio != NULL) {
                if (error == 0)
                        ktruio->uio_resid = cnt;
                ktrgenio(fd, UIO_WRITE, ktruio, error);
        }
#endif

        *cntp = cnt;
        return (error);
}

/*
 * Truncate a file given a file descriptor.
 *
 * Can't use fget_write() here, since must return EINVAL and not EBADF if the
 * descriptor isn't writable.
 */
int
kern_ftruncate(struct thread *td, int fd, off_t length)
{
        struct file *fp;
        int error;

        AUDIT_ARG_FD(fd);
        if (length < 0)
                return (EXTERROR(EINVAL, "negative length"));
        error = fget(td, fd, &cap_ftruncate_rights, &fp);
        if (error)
                return (error);
        AUDIT_ARG_FILE(td->td_proc, fp);
        if (!(fp->f_flag & FWRITE)) {
                fdrop(fp, td);
                return (EXTERROR(EINVAL, "non-writable"));
        }
        error = fo_truncate(fp, length, td->td_ucred, td);
        fdrop(fp, td);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct ftruncate_args {
        int     fd;
        int     pad;
        off_t   length;
};
#endif
int
sys_ftruncate(struct thread *td, struct ftruncate_args *uap)
{

        return (kern_ftruncate(td, uap->fd, uap->length));
}

#if defined(COMPAT_43)
#ifndef _SYS_SYSPROTO_H_
struct oftruncate_args {
        int     fd;
        long    length;
};
#endif
int
oftruncate(struct thread *td, struct oftruncate_args *uap)
{

        return (kern_ftruncate(td, uap->fd, uap->length));
}
#endif /* COMPAT_43 */

#ifndef _SYS_SYSPROTO_H_
struct ioctl_args {
        int     fd;
        u_long  com;
        caddr_t data;
};
#endif
/* ARGSUSED */
int
sys_ioctl(struct thread *td, struct ioctl_args *uap)
{
        u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(SYS_IOCTL_SMALL_ALIGN);
        uint32_t com;
        int arg, error;
        u_int size;
        caddr_t data;

#ifdef INVARIANTS
        if (uap->com > 0xffffffff) {
                printf(
                    "WARNING pid %d (%s): ioctl sign-extension ioctl %lx\n",
                    td->td_proc->p_pid, td->td_name, uap->com);
        }
#endif
        com = (uint32_t)uap->com;

        /*
         * Interpret high order word to find amount of data to be
         * copied to/from the user's address space.
         */
        size = IOCPARM_LEN(com);
        if ((size > IOCPARM_MAX) ||
            ((com & (IOC_VOID  | IOC_IN | IOC_OUT)) == 0) ||
#if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
            ((com & IOC_OUT) && size == 0) ||
#else
            ((com & (IOC_IN | IOC_OUT)) && size == 0) ||
#endif
            ((com & IOC_VOID) && size > 0 && size != sizeof(int)))
                return (ENOTTY);

        if (size > 0) {
                if (com & IOC_VOID) {
                        /* Integer argument. */
                        arg = (intptr_t)uap->data;
                        data = (void *)&arg;
                        size = 0;
                } else {
                        if (size > SYS_IOCTL_SMALL_SIZE)
                                data = malloc((u_long)size, M_IOCTLOPS, M_WAITOK);
                        else
                                data = smalldata;
                }
        } else
                data = (void *)&uap->data;
        if (com & IOC_IN) {
                error = copyin(uap->data, data, (u_int)size);
                if (error != 0)
                        goto out;
        } else if (com & IOC_OUT) {
                /*
                 * Zero the buffer so the user always
                 * gets back something deterministic.
                 */
                bzero(data, size);
        }

        error = kern_ioctl(td, uap->fd, com, data);

        if (error == 0 && (com & IOC_OUT))
                error = copyout(data, uap->data, (u_int)size);

out:
        if (size > SYS_IOCTL_SMALL_SIZE)
                free(data, M_IOCTLOPS);
        return (error);
}

int
kern_ioctl(struct thread *td, int fd, u_long com, caddr_t data)
{
        struct file *fp;
        struct filedesc *fdp;
        int error, f_flag, tmp, locked;

        AUDIT_ARG_FD(fd);
        AUDIT_ARG_CMD(com);

        fdp = td->td_proc->p_fd;

        switch (com) {
        case FIONCLEX:
        case FIOCLEX:
                FILEDESC_XLOCK(fdp);
                locked = LA_XLOCKED;
                break;
        default:
#ifdef CAPABILITIES
                FILEDESC_SLOCK(fdp);
                locked = LA_SLOCKED;
#else
                locked = LA_UNLOCKED;
#endif
                break;
        }

#ifdef CAPABILITIES
        if ((fp = fget_noref(fdp, fd)) == NULL) {
                error = EBADF;
                goto out;
        }
        if ((error = cap_ioctl_check(fdp, fd, com)) != 0) {
                fp = NULL;      /* fhold() was not called yet */
                goto out;
        }
        if (!fhold(fp)) {
                error = EBADF;
                fp = NULL;
                goto out;
        }
        if (locked == LA_SLOCKED) {
                FILEDESC_SUNLOCK(fdp);
                locked = LA_UNLOCKED;
        }
#else
        error = fget(td, fd, &cap_ioctl_rights, &fp);
        if (error != 0) {
                fp = NULL;
                goto out;
        }
#endif
        if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
                error = EBADF;
                goto out;
        }

        f_flag = 0;
        switch (com) {
        case FIONCLEX:
                fdp->fd_ofiles[fd].fde_flags &= ~UF_EXCLOSE;
                break;
        case FIOCLEX:
                fdp->fd_ofiles[fd].fde_flags |= UF_EXCLOSE;
                break;
        case FIONBIO:
        case FIOASYNC:
                f_flag = com == FIONBIO ? FNONBLOCK : FASYNC;
                tmp = *(int *)data;
                fsetfl_lock(fp);
                if (((fp->f_flag & f_flag) != 0) != (tmp != 0)) {
                        error = fo_ioctl(fp, com, (void *)&tmp, td->td_ucred,
                            td);
                        if (error == 0) {
                                if (tmp != 0)
                                        atomic_set_int(&fp->f_flag, f_flag);
                                else
                                        atomic_clear_int(&fp->f_flag, f_flag);
                        }
                }
                fsetfl_unlock(fp);
                break;
        default:
                error = fo_ioctl(fp, com, data, td->td_ucred, td);
                break;
        }

out:
        switch (locked) {
        case LA_XLOCKED:
                FILEDESC_XUNLOCK(fdp);
                break;
#ifdef CAPABILITIES
        case LA_SLOCKED:
                FILEDESC_SUNLOCK(fdp);
                break;
#endif
        default:
                FILEDESC_UNLOCK_ASSERT(fdp);
                break;
        }
        if (fp != NULL)
                fdrop(fp, td);
        return (error);
}

int
sys_posix_fallocate(struct thread *td, struct posix_fallocate_args *uap)
{
        int error;

        error = kern_posix_fallocate(td, uap->fd, uap->offset, uap->len);
        return (kern_posix_error(td, error));
}

int
kern_posix_fallocate(struct thread *td, int fd, off_t offset, off_t len)
{
        struct file *fp;
        int error;

        AUDIT_ARG_FD(fd);
        if (offset < 0)
                return (EXTERROR(EINVAL, "negative offset"));
        if (len <= 0)
                return (EXTERROR(EINVAL, "negative length"));
        /* Check for wrap. */
        if (offset > OFF_MAX - len)
                return (EFBIG);
        AUDIT_ARG_FD(fd);
        error = fget(td, fd, &cap_pwrite_rights, &fp);
        if (error != 0)
                return (error);
        AUDIT_ARG_FILE(td->td_proc, fp);
        if ((fp->f_ops->fo_flags & DFLAG_SEEKABLE) == 0) {
                error = ESPIPE;
                goto out;
        }
        if ((fp->f_flag & FWRITE) == 0) {
                error = EBADF;
                goto out;
        }

        error = fo_fallocate(fp, offset, len, td);
 out:
        fdrop(fp, td);
        return (error);
}

int
sys_fspacectl(struct thread *td, struct fspacectl_args *uap)
{
        struct spacectl_range rqsr, rmsr;
        int error, cerror;

        error = copyin(uap->rqsr, &rqsr, sizeof(rqsr));
        if (error != 0)
                return (error);

        error = kern_fspacectl(td, uap->fd, uap->cmd, &rqsr, uap->flags,
            &rmsr);
        if (uap->rmsr != NULL) {
                cerror = copyout(&rmsr, uap->rmsr, sizeof(rmsr));
                if (error == 0)
                        error = cerror;
        }
        return (error);
}

int
kern_fspacectl(struct thread *td, int fd, int cmd,
    const struct spacectl_range *rqsr, int flags, struct spacectl_range *rmsrp)
{
        struct file *fp;
        struct spacectl_range rmsr;
        int error;

        AUDIT_ARG_FD(fd);
        AUDIT_ARG_CMD(cmd);
        AUDIT_ARG_FFLAGS(flags);

        if (rqsr == NULL)
                return (EXTERROR(EINVAL, "no range"));
        rmsr = *rqsr;
        if (rmsrp != NULL)
                *rmsrp = rmsr;

        if (cmd != SPACECTL_DEALLOC)
                return (EXTERROR(EINVAL, "cmd", cmd));
        if (rqsr->r_offset < 0)
                return (EXTERROR(EINVAL, "neg offset"));
        if (rqsr->r_len <= 0)
                return (EXTERROR(EINVAL, "neg len"));
        if (rqsr->r_offset > OFF_MAX - rqsr->r_len)
                return (EXTERROR(EINVAL, "offset too large"));
        if ((flags & ~SPACECTL_F_SUPPORTED) != 0)
                return (EXTERROR(EINVAL, "reserved flags", flags));

        error = fget_write(td, fd, &cap_pwrite_rights, &fp);
        if (error != 0)
                return (error);
        AUDIT_ARG_FILE(td->td_proc, fp);
        if ((fp->f_ops->fo_flags & DFLAG_SEEKABLE) == 0) {
                error = ESPIPE;
                goto out;
        }
        if ((fp->f_flag & FWRITE) == 0) {
                error = EBADF;
                goto out;
        }

        error = fo_fspacectl(fp, cmd, &rmsr.r_offset, &rmsr.r_len, flags,
            td->td_ucred, td);
        /* fspacectl is not restarted after signals if the file is modified. */
        if (rmsr.r_len != rqsr->r_len && (error == ERESTART ||
            error == EINTR || error == EWOULDBLOCK))
                error = 0;
        if (rmsrp != NULL)
                *rmsrp = rmsr;
out:
        fdrop(fp, td);
        return (error);
}

int
kern_specialfd(struct thread *td, int type, void *arg)
{
        struct file *fp;
        int error, fd, fflags;

        fflags = 0;
        error = falloc_noinstall(td, &fp);
        if (error != 0)
                return (error);

        switch (type) {
        case SPECIALFD_EVENTFD: {
                struct specialfd_eventfd *ae;

                ae = arg;
                if ((ae->flags & EFD_CLOEXEC) != 0)
                        fflags |= O_CLOEXEC;
                error = eventfd_create_file(td, fp, ae->initval, ae->flags);
                break;
        }
        case SPECIALFD_INOTIFY: {
                struct specialfd_inotify *si;

                si = arg;
                error = inotify_create_file(td, fp, si->flags, &fflags);
                break;
        }
        default:
                error = EXTERROR(EINVAL, "invalid type", type);
                break;
        }

        if (error == 0)
                error = finstall(td, fp, &fd, fflags, NULL);
        fdrop(fp, td);
        if (error == 0)
                td->td_retval[0] = fd;
        return (error);
}

int
sys___specialfd(struct thread *td, struct __specialfd_args *args)
{
        int error;

        switch (args->type) {
        case SPECIALFD_EVENTFD: {
                struct specialfd_eventfd ae;

                if (args->len != sizeof(struct specialfd_eventfd)) {
                        error = EXTERROR(EINVAL, "eventfd params ABI");
                        break;
                }
                error = copyin(args->req, &ae, sizeof(ae));
                if (error != 0)
                        break;
                if ((ae.flags & ~(EFD_CLOEXEC | EFD_NONBLOCK |
                    EFD_SEMAPHORE)) != 0) {
                        error = EXTERROR(EINVAL, "reserved flag");
                        break;
                }
                error = kern_specialfd(td, args->type, &ae);
                break;
        }
        case SPECIALFD_INOTIFY: {
                struct specialfd_inotify si;

                if (args->len != sizeof(si)) {
                        error = EINVAL;
                        break;
                }
                error = copyin(args->req, &si, sizeof(si));
                if (error != 0)
                        break;
                error = kern_specialfd(td, args->type, &si);
                break;
        }
        default:
                error = EXTERROR(EINVAL, "unknown type", args->type);
                break;
        }
        return (error);
}

int
poll_no_poll(int events)
{
        /*
         * Return true for read/write.  If the user asked for something
         * special, return POLLNVAL, so that clients have a way of
         * determining reliably whether or not the extended
         * functionality is present without hard-coding knowledge
         * of specific filesystem implementations.
         */
        if (events & ~POLLSTANDARD)
                return (POLLNVAL);

        return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
}

int
sys_pselect(struct thread *td, struct pselect_args *uap)
{
        struct timespec ts;
        struct timeval tv, *tvp;
        sigset_t set, *uset;
        int error;

        if (uap->ts != NULL) {
                error = copyin(uap->ts, &ts, sizeof(ts));
                if (error != 0)
                    return (error);
                TIMESPEC_TO_TIMEVAL(&tv, &ts);
                tvp = &tv;
        } else
                tvp = NULL;
        if (uap->sm != NULL) {
                error = copyin(uap->sm, &set, sizeof(set));
                if (error != 0)
                        return (error);
                uset = &set;
        } else
                uset = NULL;
        return (kern_pselect(td, uap->nd, uap->in, uap->ou, uap->ex, tvp,
            uset, NFDBITS));
}

int
kern_pselect(struct thread *td, int nd, fd_set *in, fd_set *ou, fd_set *ex,
    struct timeval *tvp, sigset_t *uset, int abi_nfdbits)
{
        int error;

        if (uset != NULL) {
                error = kern_sigprocmask(td, SIG_SETMASK, uset,
                    &td->td_oldsigmask, 0);
                if (error != 0)
                        return (error);
                td->td_pflags |= TDP_OLDMASK;
        }
        error = kern_select(td, nd, in, ou, ex, tvp, abi_nfdbits);
        if (uset != NULL) {
                /*
                 * Make sure that ast() is called on return to
                 * usermode and TDP_OLDMASK is cleared, restoring old
                 * sigmask.  If we didn't get interrupted, then the caller is
                 * likely not expecting a signal to hit that should normally be
                 * blocked by its signal mask, so we restore the mask before
                 * any signals could be delivered.
                 */
                if (error == EINTR) {
                        ast_sched(td, TDA_SIGSUSPEND);
                } else {
                        /* *select(2) should never restart. */
                        MPASS(error != ERESTART);
                        ast_sched(td, TDA_PSELECT);
                }
        }

        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct select_args {
        int     nd;
        fd_set  *in, *ou, *ex;
        struct  timeval *tv;
};
#endif
int
sys_select(struct thread *td, struct select_args *uap)
{
        struct timeval tv, *tvp;
        int error;

        if (uap->tv != NULL) {
                error = copyin(uap->tv, &tv, sizeof(tv));
                if (error)
                        return (error);
                tvp = &tv;
        } else
                tvp = NULL;

        return (kern_select(td, uap->nd, uap->in, uap->ou, uap->ex, tvp,
            NFDBITS));
}

/*
 * In the unlikely case when user specified n greater then the last
 * open file descriptor, check that no bits are set after the last
 * valid fd.  We must return EBADF if any is set.
 *
 * There are applications that rely on the behaviour.
 *
 * nd is fd_nfiles.
 */
static int
select_check_badfd(fd_set *fd_in, int nd, int ndu, int abi_nfdbits)
{
        char *addr, *oaddr;
        int b, i, res;
        uint8_t bits;

        if (nd >= ndu || fd_in == NULL)
                return (0);

        oaddr = NULL;
        bits = 0; /* silence gcc */
        for (i = nd; i < ndu; i++) {
                b = i / NBBY;
#if BYTE_ORDER == LITTLE_ENDIAN
                addr = (char *)fd_in + b;
#else
                addr = (char *)fd_in;
                if (abi_nfdbits == NFDBITS) {
                        addr += rounddown(b, sizeof(fd_mask)) +
                            sizeof(fd_mask) - 1 - b % sizeof(fd_mask);
                } else {
                        addr += rounddown(b, sizeof(uint32_t)) +
                            sizeof(uint32_t) - 1 - b % sizeof(uint32_t);
                }
#endif
                if (addr != oaddr) {
                        res = fubyte(addr);
                        if (res == -1)
                                return (EFAULT);
                        oaddr = addr;
                        bits = res;
                }
                if ((bits & (1 << (i % NBBY))) != 0)
                        return (EBADF);
        }
        return (0);
}

int
kern_select(struct thread *td, int nd, fd_set *fd_in, fd_set *fd_ou,
    fd_set *fd_ex, struct timeval *tvp, int abi_nfdbits)
{
        struct filedesc *fdp;
        /*
         * The magic 2048 here is chosen to be just enough for FD_SETSIZE
         * infds with the new FD_SETSIZE of 1024, and more than enough for
         * FD_SETSIZE infds, outfds and exceptfds with the old FD_SETSIZE
         * of 256.
         */
        fd_mask s_selbits[howmany(2048, NFDBITS)];
        fd_mask *ibits[3], *obits[3], *selbits, *sbp;
        struct timeval rtv;
        sbintime_t asbt, precision, rsbt;
        u_int nbufbytes, ncpbytes, ncpubytes, nfdbits;
        int error, lf, ndu;

        if (nd < 0)
                return (EXTERROR(EINVAL, "negative ndescs"));
        fdp = td->td_proc->p_fd;
        ndu = nd;
        lf = fdp->fd_nfiles;
        if (nd > lf)
                nd = lf;

        error = select_check_badfd(fd_in, nd, ndu, abi_nfdbits);
        if (error != 0)
                return (error);
        error = select_check_badfd(fd_ou, nd, ndu, abi_nfdbits);
        if (error != 0)
                return (error);
        error = select_check_badfd(fd_ex, nd, ndu, abi_nfdbits);
        if (error != 0)
                return (error);

        /*
         * Allocate just enough bits for the non-null fd_sets.  Use the
         * preallocated auto buffer if possible.
         */
        nfdbits = roundup(nd, NFDBITS);
        ncpbytes = nfdbits / NBBY;
        ncpubytes = roundup(nd, abi_nfdbits) / NBBY;
        nbufbytes = 0;
        if (fd_in != NULL)
                nbufbytes += 2 * ncpbytes;
        if (fd_ou != NULL)
                nbufbytes += 2 * ncpbytes;
        if (fd_ex != NULL)
                nbufbytes += 2 * ncpbytes;
        if (nbufbytes <= sizeof s_selbits)
                selbits = &s_selbits[0];
        else
                selbits = malloc(nbufbytes, M_SELECT, M_WAITOK);

        /*
         * Assign pointers into the bit buffers and fetch the input bits.
         * Put the output buffers together so that they can be bzeroed
         * together.
         */
        sbp = selbits;
#define getbits(name, x) \
        do {                                                            \
                if (name == NULL) {                                     \
                        ibits[x] = NULL;                                \
                        obits[x] = NULL;                                \
                } else {                                                \
                        ibits[x] = sbp + nbufbytes / 2 / sizeof *sbp;   \
                        obits[x] = sbp;                                 \
                        sbp += ncpbytes / sizeof *sbp;                  \
                        error = copyin(name, ibits[x], ncpubytes);      \
                        if (error != 0)                                 \
                                goto done;                              \
                        if (ncpbytes != ncpubytes)                      \
                                bzero((char *)ibits[x] + ncpubytes,     \
                                    ncpbytes - ncpubytes);              \
                }                                                       \
        } while (0)
        getbits(fd_in, 0);
        getbits(fd_ou, 1);
        getbits(fd_ex, 2);
#undef  getbits

#if BYTE_ORDER == BIG_ENDIAN && defined(__LP64__)
        /*
         * XXX: swizzle_fdset assumes that if abi_nfdbits != NFDBITS,
         * we are running under 32-bit emulation. This should be more
         * generic.
         */
#define swizzle_fdset(bits)                                             \
        if (abi_nfdbits != NFDBITS && bits != NULL) {                   \
                int i;                                                  \
                for (i = 0; i < ncpbytes / sizeof *sbp; i++)            \
                        bits[i] = (bits[i] >> 32) | (bits[i] << 32);    \
        }
#else
#define swizzle_fdset(bits)
#endif

        /* Make sure the bit order makes it through an ABI transition */
        swizzle_fdset(ibits[0]);
        swizzle_fdset(ibits[1]);
        swizzle_fdset(ibits[2]);

        if (nbufbytes != 0)
                bzero(selbits, nbufbytes / 2);

        precision = 0;
        if (tvp != NULL) {
                rtv = *tvp;
                if (rtv.tv_sec < 0 || rtv.tv_usec < 0 ||
                    rtv.tv_usec >= 1000000) {
                        error = EXTERROR(EINVAL, "invalid timeval");
                        goto done;
                }
                if (!timevalisset(&rtv))
                        asbt = 0;
                else if (rtv.tv_sec <= INT32_MAX) {
                        rsbt = tvtosbt(rtv);
                        precision = rsbt;
                        precision >>= tc_precexp;
                        if (TIMESEL(&asbt, rsbt))
                                asbt += tc_tick_sbt;
                        if (asbt <= SBT_MAX - rsbt)
                                asbt += rsbt;
                        else
                                asbt = -1;
                } else
                        asbt = -1;
        } else
                asbt = -1;
        seltdinit(td);
        /* Iterate until the timeout expires or descriptors become ready. */
        for (;;) {
                error = selscan(td, ibits, obits, nd);
                if (error || td->td_retval[0] != 0)
                        break;
                error = seltdwait(td, asbt, precision);
                if (error)
                        break;
                error = selrescan(td, ibits, obits);
                if (error || td->td_retval[0] != 0)
                        break;
        }
        seltdclear(td);

done:
        /* select is not restarted after signals... */
        if (error == ERESTART)
                error = EINTR;
        if (error == EWOULDBLOCK)
                error = 0;

        /* swizzle bit order back, if necessary */
        swizzle_fdset(obits[0]);
        swizzle_fdset(obits[1]);
        swizzle_fdset(obits[2]);
#undef swizzle_fdset

#define putbits(name, x) \
        if (name && (error2 = copyout(obits[x], name, ncpubytes))) \
                error = error2;
        if (error == 0) {
                int error2;

                putbits(fd_in, 0);
                putbits(fd_ou, 1);
                putbits(fd_ex, 2);
#undef putbits
        }
        if (selbits != &s_selbits[0])
                free(selbits, M_SELECT);

        return (error);
}
/* 
 * Convert a select bit set to poll flags.
 *
 * The backend always returns POLLHUP/POLLERR if appropriate and we
 * return this as a set bit in any set.
 */
static const int select_flags[3] = {
    POLLRDNORM | POLLHUP | POLLERR,
    POLLWRNORM | POLLHUP | POLLERR,
    POLLRDBAND | POLLERR
};

/*
 * Compute the fo_poll flags required for a fd given by the index and
 * bit position in the fd_mask array.
 */
static __inline int
selflags(fd_mask **ibits, int idx, fd_mask bit)
{
        int flags;
        int msk;

        flags = 0;
        for (msk = 0; msk < 3; msk++) {
                if (ibits[msk] == NULL)
                        continue;
                if ((ibits[msk][idx] & bit) == 0)
                        continue;
                flags |= select_flags[msk];
        }
        return (flags);
}

/*
 * Set the appropriate output bits given a mask of fired events and the
 * input bits originally requested.
 */
static __inline int
selsetbits(fd_mask **ibits, fd_mask **obits, int idx, fd_mask bit, int events)
{
        int msk;
        int n;

        n = 0;
        for (msk = 0; msk < 3; msk++) {
                if ((events & select_flags[msk]) == 0)
                        continue;
                if (ibits[msk] == NULL)
                        continue;
                if ((ibits[msk][idx] & bit) == 0)
                        continue;
                /*
                 * XXX Check for a duplicate set.  This can occur because a
                 * socket calls selrecord() twice for each poll() call
                 * resulting in two selfds per real fd.  selrescan() will
                 * call selsetbits twice as a result.
                 */
                if ((obits[msk][idx] & bit) != 0)
                        continue;
                obits[msk][idx] |= bit;
                n++;
        }

        return (n);
}

/*
 * Traverse the list of fds attached to this thread's seltd and check for
 * completion.
 */
static int
selrescan(struct thread *td, fd_mask **ibits, fd_mask **obits)
{
        struct filedesc *fdp;
        struct selinfo *si;
        struct seltd *stp;
        struct selfd *sfp;
        struct selfd *sfn;
        struct file *fp;
        fd_mask bit;
        int fd, ev, n, idx;
        int error;
        bool only_user;

        fdp = td->td_proc->p_fd;
        stp = td->td_sel;
        n = 0;
        only_user = FILEDESC_IS_ONLY_USER(fdp);
        STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn) {
                fd = (int)(uintptr_t)sfp->sf_cookie;
                si = sfp->sf_si;
                selfdfree(stp, sfp);
                /* If the selinfo wasn't cleared the event didn't fire. */
                if (si != NULL)
                        continue;
                if (only_user)
                        error = fget_only_user(fdp, fd, &cap_event_rights, &fp);
                else
                        error = fget_unlocked(td, fd, &cap_event_rights, &fp);
                if (__predict_false(error != 0))
                        return (error);
                idx = fd / NFDBITS;
                bit = (fd_mask)1 << (fd % NFDBITS);
                ev = fo_poll(fp, selflags(ibits, idx, bit), td->td_ucred, td);
                if (only_user)
                        fput_only_user(fdp, fp);
                else
                        fdrop(fp, td);
                if (ev != 0)
                        n += selsetbits(ibits, obits, idx, bit, ev);
        }
        stp->st_flags = 0;
        td->td_retval[0] = n;
        return (0);
}

/*
 * Perform the initial filedescriptor scan and register ourselves with
 * each selinfo.
 */
static int
selscan(struct thread *td, fd_mask **ibits, fd_mask **obits, int nfd)
{
        struct filedesc *fdp;
        struct file *fp;
        fd_mask bit;
        int ev, flags, end, fd;
        int n, idx;
        int error;
        bool only_user;

        fdp = td->td_proc->p_fd;
        n = 0;
        only_user = FILEDESC_IS_ONLY_USER(fdp);
        for (idx = 0, fd = 0; fd < nfd; idx++) {
                end = imin(fd + NFDBITS, nfd);
                for (bit = 1; fd < end; bit <<= 1, fd++) {
                        /* Compute the list of events we're interested in. */
                        flags = selflags(ibits, idx, bit);
                        if (flags == 0)
                                continue;
                        if (only_user)
                                error = fget_only_user(fdp, fd, &cap_event_rights, &fp);
                        else
                                error = fget_unlocked(td, fd, &cap_event_rights, &fp);
                        if (__predict_false(error != 0))
                                return (error);
                        selfdalloc(td, (void *)(uintptr_t)fd);
                        ev = fo_poll(fp, flags, td->td_ucred, td);
                        if (only_user)
                                fput_only_user(fdp, fp);
                        else
                                fdrop(fp, td);
                        if (ev != 0)
                                n += selsetbits(ibits, obits, idx, bit, ev);
                }
        }

        td->td_retval[0] = n;
        return (0);
}

int
sys_poll(struct thread *td, struct poll_args *uap)
{
        struct timespec ts, *tsp;

        if (uap->timeout != INFTIM) {
                if (uap->timeout < 0)
                        return (EXTERROR(EINVAL, "invalid timeout"));
                ts.tv_sec = uap->timeout / 1000;
                ts.tv_nsec = (uap->timeout % 1000) * 1000000;
                tsp = &ts;
        } else
                tsp = NULL;

        return (kern_poll(td, uap->fds, uap->nfds, tsp, NULL));
}

/*
 * kfds points to an array in the kernel.
 */
int
kern_poll_kfds(struct thread *td, struct pollfd *kfds, u_int nfds,
    struct timespec *tsp, sigset_t *uset)
{
        sbintime_t sbt, precision, tmp;
        time_t over;
        struct timespec ts;
        int error;

        precision = 0;
        if (tsp != NULL) {
                if (!timespecvalid_interval(tsp))
                        return (EXTERROR(EINVAL, "invalid timespec"));
                if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
                        sbt = 0;
                else {
                        ts = *tsp;
                        if (ts.tv_sec > INT32_MAX / 2) {
                                over = ts.tv_sec - INT32_MAX / 2;
                                ts.tv_sec -= over;
                        } else
                                over = 0;
                        tmp = tstosbt(ts);
                        precision = tmp;
                        precision >>= tc_precexp;
                        if (TIMESEL(&sbt, tmp))
                                sbt += tc_tick_sbt;
                        sbt += tmp;
                }
        } else
                sbt = -1;

        if (uset != NULL) {
                error = kern_sigprocmask(td, SIG_SETMASK, uset,
                    &td->td_oldsigmask, 0);
                if (error)
                        return (error);
                td->td_pflags |= TDP_OLDMASK;
        }

        seltdinit(td);
        /* Iterate until the timeout expires or descriptors become ready. */
        for (;;) {
                error = pollscan(td, kfds, nfds);
                if (error || td->td_retval[0] != 0)
                        break;
                error = seltdwait(td, sbt, precision);
                if (error)
                        break;
                error = pollrescan(td);
                if (error || td->td_retval[0] != 0)
                        break;
        }
        seltdclear(td);

        /* poll is not restarted after signals... */
        if (error == ERESTART)
                error = EINTR;
        if (error == EWOULDBLOCK)
                error = 0;

        if (uset != NULL) {
                /*
                 * Make sure that ast() is called on return to
                 * usermode and TDP_OLDMASK is cleared, restoring old
                 * sigmask.  If we didn't get interrupted, then the caller is
                 * likely not expecting a signal to hit that should normally be
                 * blocked by its signal mask, so we restore the mask before
                 * any signals could be delivered.
                 */
                if (error == EINTR)
                        ast_sched(td, TDA_SIGSUSPEND);
                else
                        ast_sched(td, TDA_PSELECT);
        }

        return (error);
}

int
sys_ppoll(struct thread *td, struct ppoll_args *uap)
{
        struct timespec ts, *tsp;
        sigset_t set, *ssp;
        int error;

        if (uap->ts != NULL) {
                error = copyin(uap->ts, &ts, sizeof(ts));
                if (error)
                        return (error);
                tsp = &ts;
        } else
                tsp = NULL;
        if (uap->set != NULL) {
                error = copyin(uap->set, &set, sizeof(set));
                if (error)
                        return (error);
                ssp = &set;
        } else
                ssp = NULL;
        return (kern_poll(td, uap->fds, uap->nfds, tsp, ssp));
}

/*
 * ufds points to an array in user space.
 */
int
kern_poll(struct thread *td, struct pollfd *ufds, u_int nfds,
    struct timespec *tsp, sigset_t *set)
{
        struct pollfd *kfds;
        struct pollfd stackfds[32];
        int error;

        if (kern_poll_maxfds(nfds))
                return (EXTERROR(EINVAL, "too large nfds"));
        if (nfds > nitems(stackfds))
                kfds = mallocarray(nfds, sizeof(*kfds), M_TEMP, M_WAITOK);
        else
                kfds = stackfds;
        error = copyin(ufds, kfds, nfds * sizeof(*kfds));
        if (error != 0)
                goto out;

        error = kern_poll_kfds(td, kfds, nfds, tsp, set);
        if (error == 0)
                error = pollout(td, kfds, ufds, nfds);
#ifdef KTRACE
        if (error == 0 && KTRPOINT(td, KTR_STRUCT_ARRAY))
                ktrstructarray("pollfd", UIO_USERSPACE, ufds, nfds,
                    sizeof(*ufds));
#endif

out:
        if (nfds > nitems(stackfds))
                free(kfds, M_TEMP);
        return (error);
}

bool
kern_poll_maxfds(u_int nfds)
{

        /*
         * This is kinda bogus.  We have fd limits, but that is not
         * really related to the size of the pollfd array.  Make sure
         * we let the process use at least FD_SETSIZE entries and at
         * least enough for the system-wide limits.  We want to be reasonably
         * safe, but not overly restrictive.
         */
        return (nfds > maxfilesperproc && nfds > FD_SETSIZE);
}

static int
pollrescan(struct thread *td)
{
        struct seltd *stp;
        struct selfd *sfp;
        struct selfd *sfn;
        struct selinfo *si;
        struct filedesc *fdp;
        struct file *fp;
        struct pollfd *fd;
        int n, error;
        bool only_user;

        n = 0;
        fdp = td->td_proc->p_fd;
        stp = td->td_sel;
        only_user = FILEDESC_IS_ONLY_USER(fdp);
        STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn) {
                fd = (struct pollfd *)sfp->sf_cookie;
                si = sfp->sf_si;
                selfdfree(stp, sfp);
                /* If the selinfo wasn't cleared the event didn't fire. */
                if (si != NULL)
                        continue;
                if (only_user)
                        error = fget_only_user(fdp, fd->fd, &cap_event_rights, &fp);
                else
                        error = fget_unlocked(td, fd->fd, &cap_event_rights, &fp);
                if (__predict_false(error != 0)) {
                        fd->revents = POLLNVAL;
                        n++;
                        continue;
                }
                /*
                 * Note: backend also returns POLLHUP and
                 * POLLERR if appropriate.
                 */
                fd->revents = fo_poll(fp, fd->events, td->td_ucred, td);
                if (only_user)
                        fput_only_user(fdp, fp);
                else
                        fdrop(fp, td);
                if (fd->revents != 0)
                        n++;
        }
        stp->st_flags = 0;
        td->td_retval[0] = n;
        return (0);
}

static int
pollout(struct thread *td, struct pollfd *fds, struct pollfd *ufds, u_int nfd)
{
        int error = 0;
        u_int i = 0;
        u_int n = 0;

        for (i = 0; i < nfd; i++) {
                error = copyout(&fds->revents, &ufds->revents,
                    sizeof(ufds->revents));
                if (error)
                        return (error);
                if (fds->revents != 0)
                        n++;
                fds++;
                ufds++;
        }
        td->td_retval[0] = n;
        return (0);
}

static int
pollscan(struct thread *td, struct pollfd *fds, u_int nfd)
{
        struct filedesc *fdp;
        struct file *fp;
        int i, n, error;
        bool only_user;

        n = 0;
        fdp = td->td_proc->p_fd;
        only_user = FILEDESC_IS_ONLY_USER(fdp);
        for (i = 0; i < nfd; i++, fds++) {
                if (fds->fd < 0) {
                        fds->revents = 0;
                        continue;
                }
                if (only_user)
                        error = fget_only_user(fdp, fds->fd, &cap_event_rights, &fp);
                else
                        error = fget_unlocked(td, fds->fd, &cap_event_rights, &fp);
                if (__predict_false(error != 0)) {
                        fds->revents = POLLNVAL;
                        n++;
                        continue;
                }
                /*
                 * Note: backend also returns POLLHUP and
                 * POLLERR if appropriate.
                 */
                selfdalloc(td, fds);
                fds->revents = fo_poll(fp, fds->events,
                    td->td_ucred, td);
                if (only_user)
                        fput_only_user(fdp, fp);
                else
                        fdrop(fp, td);
                /*
                 * POSIX requires POLLOUT to be never
                 * set simultaneously with POLLHUP.
                 */
                if ((fds->revents & POLLHUP) != 0)
                        fds->revents &= ~POLLOUT;

                if (fds->revents != 0)
                        n++;
        }
        td->td_retval[0] = n;
        return (0);
}

/*
 * XXX This was created specifically to support netncp and netsmb.  This
 * allows the caller to specify a socket to wait for events on.  It returns
 * 0 if any events matched and an error otherwise.  There is no way to
 * determine which events fired.
 */
int
selsocket(struct socket *so, int events, struct timeval *tvp, struct thread *td)
{
        struct timeval rtv;
        sbintime_t asbt, precision, rsbt;
        int error;

        precision = 0;  /* stupid gcc! */
        if (tvp != NULL) {
                rtv = *tvp;
                if (rtv.tv_sec < 0 || rtv.tv_usec < 0 || 
                    rtv.tv_usec >= 1000000)
                        return (EXTERROR(EINVAL, "invalid timeval"));
                if (!timevalisset(&rtv))
                        asbt = 0;
                else if (rtv.tv_sec <= INT32_MAX) {
                        rsbt = tvtosbt(rtv);
                        precision = rsbt;
                        precision >>= tc_precexp;
                        if (TIMESEL(&asbt, rsbt))
                                asbt += tc_tick_sbt;
                        if (asbt <= SBT_MAX - rsbt)
                                asbt += rsbt;
                        else
                                asbt = -1;
                } else
                        asbt = -1;
        } else
                asbt = -1;
        seltdinit(td);
        /*
         * Iterate until the timeout expires or the socket becomes ready.
         */
        for (;;) {
                selfdalloc(td, NULL);
                if (so->so_proto->pr_sopoll(so, events, td) != 0) {
                        error = 0;
                        break;
                }
                error = seltdwait(td, asbt, precision);
                if (error)
                        break;
        }
        seltdclear(td);
        /* XXX Duplicates ncp/smb behavior. */
        if (error == ERESTART)
                error = 0;
        return (error);
}

/*
 * Preallocate two selfds associated with 'cookie'.  Some fo_poll routines
 * have two select sets, one for read and another for write.
 */
static void
selfdalloc(struct thread *td, void *cookie)
{
        struct seltd *stp;

        stp = td->td_sel;
        if (stp->st_free1 == NULL)
                stp->st_free1 = malloc(sizeof(*stp->st_free1), M_SELFD, M_WAITOK|M_ZERO);
        stp->st_free1->sf_td = stp;
        stp->st_free1->sf_cookie = cookie;
        if (stp->st_free2 == NULL)
                stp->st_free2 = malloc(sizeof(*stp->st_free2), M_SELFD, M_WAITOK|M_ZERO);
        stp->st_free2->sf_td = stp;
        stp->st_free2->sf_cookie = cookie;
}

static void
selfdfree(struct seltd *stp, struct selfd *sfp)
{
        STAILQ_REMOVE(&stp->st_selq, sfp, selfd, sf_link);
        /*
         * Paired with doselwakeup.
         */
        if (atomic_load_acq_ptr((uintptr_t *)&sfp->sf_si) != (uintptr_t)NULL) {
                mtx_lock(sfp->sf_mtx);
                if (sfp->sf_si != NULL) {
                        TAILQ_REMOVE(&sfp->sf_si->si_tdlist, sfp, sf_threads);
                }
                mtx_unlock(sfp->sf_mtx);
        }
        free(sfp, M_SELFD);
}

/* Drain the waiters tied to all the selfd belonging the specified selinfo. */
void
seldrain(struct selinfo *sip)
{

        /*
         * This feature is already provided by doselwakeup(), thus it is
         * enough to go for it.
         * Eventually, the context, should take care to avoid races
         * between thread calling select()/poll() and file descriptor
         * detaching, but, again, the races are just the same as
         * selwakeup().
         */
        doselwakeup(sip, -1);
}

/*
 * Record a select request.
 */
void
selrecord(struct thread *selector, struct selinfo *sip)
{
        struct selfd *sfp;
        struct seltd *stp;
        struct mtx *mtxp;

        stp = selector->td_sel;
        /*
         * Don't record when doing a rescan.
         */
        if (stp->st_flags & SELTD_RESCAN)
                return;
        /*
         * Grab one of the preallocated descriptors.
         */
        sfp = NULL;
        if ((sfp = stp->st_free1) != NULL)
                stp->st_free1 = NULL;
        else if ((sfp = stp->st_free2) != NULL)
                stp->st_free2 = NULL;
        else
                panic("selrecord: No free selfd on selq");
        mtxp = sip->si_mtx;
        if (mtxp == NULL)
                mtxp = mtx_pool_find(mtxpool_select, sip);
        /*
         * Initialize the sfp and queue it in the thread.
         */
        sfp->sf_si = sip;
        sfp->sf_mtx = mtxp;
        STAILQ_INSERT_TAIL(&stp->st_selq, sfp, sf_link);
        /*
         * Now that we've locked the sip, check for initialization.
         */
        mtx_lock(mtxp);
        if (sip->si_mtx == NULL) {
                sip->si_mtx = mtxp;
                TAILQ_INIT(&sip->si_tdlist);
        }
        /*
         * Add this thread to the list of selfds listening on this selinfo.
         */
        TAILQ_INSERT_TAIL(&sip->si_tdlist, sfp, sf_threads);
        mtx_unlock(sip->si_mtx);
}

/* Wake up a selecting thread. */
void
selwakeup(struct selinfo *sip)
{
        doselwakeup(sip, -1);
}

/* Wake up a selecting thread, and set its priority. */
void
selwakeuppri(struct selinfo *sip, int pri)
{
        doselwakeup(sip, pri);
}

/*
 * Do a wakeup when a selectable event occurs.
 */
static void
doselwakeup(struct selinfo *sip, int pri)
{
        struct selfd *sfp;
        struct selfd *sfn;
        struct seltd *stp;

        /* If it's not initialized there can't be any waiters. */
        if (sip->si_mtx == NULL)
                return;
        /*
         * Locking the selinfo locks all selfds associated with it.
         */
        mtx_lock(sip->si_mtx);
        TAILQ_FOREACH_SAFE(sfp, &sip->si_tdlist, sf_threads, sfn) {
                /*
                 * Once we remove this sfp from the list and clear the
                 * sf_si seltdclear will know to ignore this si.
                 */
                TAILQ_REMOVE(&sip->si_tdlist, sfp, sf_threads);
                stp = sfp->sf_td;
                mtx_lock(&stp->st_mtx);
                stp->st_flags |= SELTD_PENDING;
                cv_broadcastpri(&stp->st_wait, pri);
                mtx_unlock(&stp->st_mtx);
                /*
                 * Paired with selfdfree.
                 *
                 * Storing this only after the wakeup provides an invariant that
                 * stp is not used after selfdfree returns.
                 */
                atomic_store_rel_ptr((uintptr_t *)&sfp->sf_si, (uintptr_t)NULL);
        }
        mtx_unlock(sip->si_mtx);
}

static void
seltdinit(struct thread *td)
{
        struct seltd *stp;

        stp = td->td_sel;
        if (stp != NULL) {
                MPASS(stp->st_flags == 0);
                MPASS(STAILQ_EMPTY(&stp->st_selq));
                return;
        }
        stp = malloc(sizeof(*stp), M_SELECT, M_WAITOK|M_ZERO);
        mtx_init(&stp->st_mtx, "sellck", NULL, MTX_DEF);
        cv_init(&stp->st_wait, "select");
        stp->st_flags = 0;
        STAILQ_INIT(&stp->st_selq);
        td->td_sel = stp;
}

static int
seltdwait(struct thread *td, sbintime_t sbt, sbintime_t precision)
{
        struct seltd *stp;
        int error;

        stp = td->td_sel;
        /*
         * An event of interest may occur while we do not hold the seltd
         * locked so check the pending flag before we sleep.
         */
        mtx_lock(&stp->st_mtx);
        /*
         * Any further calls to selrecord will be a rescan.
         */
        stp->st_flags |= SELTD_RESCAN;
        if (stp->st_flags & SELTD_PENDING) {
                mtx_unlock(&stp->st_mtx);
                return (0);
        }
        if (sbt == 0)
                error = EWOULDBLOCK;
        else if (sbt != -1)
                error = cv_timedwait_sig_sbt(&stp->st_wait, &stp->st_mtx,
                    sbt, precision, C_ABSOLUTE);
        else
                error = cv_wait_sig(&stp->st_wait, &stp->st_mtx);
        mtx_unlock(&stp->st_mtx);

        return (error);
}

void
seltdfini(struct thread *td)
{
        struct seltd *stp;

        stp = td->td_sel;
        if (stp == NULL)
                return;
        MPASS(stp->st_flags == 0);
        MPASS(STAILQ_EMPTY(&stp->st_selq));
        if (stp->st_free1)
                free(stp->st_free1, M_SELFD);
        if (stp->st_free2)
                free(stp->st_free2, M_SELFD);
        td->td_sel = NULL;
        cv_destroy(&stp->st_wait);
        mtx_destroy(&stp->st_mtx);
        free(stp, M_SELECT);
}

/*
 * Remove the references to the thread from all of the objects we were
 * polling.
 */
static void
seltdclear(struct thread *td)
{
        struct seltd *stp;
        struct selfd *sfp;
        struct selfd *sfn;

        stp = td->td_sel;
        STAILQ_FOREACH_SAFE(sfp, &stp->st_selq, sf_link, sfn)
                selfdfree(stp, sfp);
        stp->st_flags = 0;
}

static void selectinit(void *);
SYSINIT(select, SI_SUB_SYSCALLS, SI_ORDER_ANY, selectinit, NULL);
static void
selectinit(void *dummy __unused)
{

        mtxpool_select = mtx_pool_create("select mtxpool", 128, MTX_DEF);
}

/*
 * Set up a syscall return value that follows the convention specified for
 * posix_* functions.
 */
int
kern_posix_error(struct thread *td, int error)
{

        if (error <= 0)
                return (error);
        td->td_errno = error;
        td->td_pflags |= TDP_NERRNO;
        td->td_retval[0] = error;
        return (0);
}

int
kcmp_cmp(uintptr_t a, uintptr_t b)
{
        if (a == b)
                return (0);
        else if (a < b)
                return (1);
        return (2);
}

static int
kcmp_pget(struct thread *td, pid_t pid, struct proc **pp)
{
        int error;

        if (pid == td->td_proc->p_pid) {
                *pp = td->td_proc;
                return (0);
        }
        error = pget(pid, PGET_NOTID | PGET_CANDEBUG | PGET_NOTWEXIT |
            PGET_HOLD, pp);
        MPASS(*pp != td->td_proc);
        return (error);
}

int
kern_kcmp(struct thread *td, pid_t pid1, pid_t pid2, int type,
    uintptr_t idx1, uintptr_t idx2)
{
        struct proc *p1, *p2;
        struct file *fp1, *fp2;
        int error, res;

        res = -1;
        p1 = p2 = NULL;
        error = kcmp_pget(td, pid1, &p1);
        if (error == 0)
                error = kcmp_pget(td, pid2, &p2);
        if (error != 0)
                goto out;

        switch (type) {
        case KCMP_FILE:
        case KCMP_FILEOBJ:
                error = fget_remote(td, p1, idx1, NULL, NULL, &fp1);
                if (error == 0) {
                        error = fget_remote(td, p2, idx2, NULL, NULL, &fp2);
                        if (error == 0) {
                                if (type == KCMP_FILEOBJ)
                                        res = fo_cmp(fp1, fp2, td);
                                else
                                        res = kcmp_cmp((uintptr_t)fp1,
                                            (uintptr_t)fp2);
                                fdrop(fp2, td);
                        }
                        fdrop(fp1, td);
                }
                break;
        case KCMP_FILES:
                res = kcmp_cmp((uintptr_t)p1->p_fd, (uintptr_t)p2->p_fd);
                break;
        case KCMP_SIGHAND:
                res = kcmp_cmp((uintptr_t)p1->p_sigacts,
                    (uintptr_t)p2->p_sigacts);
                break;
        case KCMP_VM:
                res = kcmp_cmp((uintptr_t)p1->p_vmspace,
                    (uintptr_t)p2->p_vmspace);
                break;
        default:
                error = EXTERROR(EINVAL, "unknown op");
                break;
        }

out:
        if (p1 != NULL && p1 != td->td_proc)
                PRELE(p1);
        if (p2 != NULL && p2 != td->td_proc)
                PRELE(p2);

        td->td_retval[0] = res;
        return (error);
}

int
sys_kcmp(struct thread *td, struct kcmp_args *uap)
{
        return (kern_kcmp(td, uap->pid1, uap->pid2, uap->type,
            uap->idx1, uap->idx2));
}

int
file_kcmp_generic(struct file *fp1, struct file *fp2, struct thread *td)
{
        if (fp1->f_type != fp2->f_type)
                return (3);
        return (kcmp_cmp((uintptr_t)fp1->f_data, (uintptr_t)fp2->f_data));
}

int
exterr_to_ue(struct thread *td, struct uexterror *ue)
{
        if ((td->td_pflags2 & TDP2_EXTERR) == 0)
                return (ENOENT);

        memset(ue, 0, sizeof(*ue));
        ue->error = td->td_kexterr.error;
        ue->cat = td->td_kexterr.cat;
        ue->src_line = td->td_kexterr.src_line;
        ue->p1 = td->td_kexterr.p1;
        ue->p2 = td->td_kexterr.p2;
        if (td->td_kexterr.msg != NULL)
                strlcpy(ue->msg, td->td_kexterr.msg, sizeof(ue->msg));
        return (0);
}

void
exterr_copyout(struct thread *td)
{
        struct uexterror ue;
        ksiginfo_t ksi;
        void *uloc;
        size_t sz;
        int error;

        MPASS((td->td_pflags2 & TDP2_UEXTERR) != 0);

        uloc = (char *)td->td_exterr_ptr + __offsetof(struct uexterror,
            error);
        error = exterr_to_ue(td, &ue);
        if (error != 0) {
                ue.error = 0;
                sz = sizeof(ue.error);
        } else {
                ktrexterr(td);
                sz = sizeof(ue) - __offsetof(struct uexterror, error);
        }
        error = copyout(&ue.error, uloc, sz);
        if (error != 0) {
                td->td_pflags2 &= ~TDP2_UEXTERR;
                ksiginfo_init_trap(&ksi);
                ksi.ksi_signo = SIGSEGV;
                ksi.ksi_code = SEGV_ACCERR;
                ksi.ksi_addr = uloc;
                trapsignal(td, &ksi);
        }
}

int
sys_exterrctl(struct thread *td, struct exterrctl_args *uap)
{
        return (kern_exterrctl(td, uap->op, uap->flags, uap->ptr));
}

int
kern_exterrctl(struct thread *td, u_int op, u_int flags, void *ptr)
{
        uint32_t ver;
        int error;

        if ((flags & ~(EXTERRCTLF_FORCE)) != 0)
                return (EINVAL);
        switch (op) {
        case EXTERRCTL_ENABLE:
                if ((td->td_pflags2 & TDP2_UEXTERR) != 0 &&
                    (flags & EXTERRCTLF_FORCE) == 0)
                        return (EBUSY);
                td->td_pflags2 &= ~TDP2_UEXTERR;
                error = copyin(ptr, &ver, sizeof(ver));
                if (error != 0)
                        return (error);
                if (ver != UEXTERROR_VER)
                        return (EINVAL);
                td->td_pflags2 |= TDP2_UEXTERR;
                td->td_exterr_ptr = ptr;
                return (0);
        case EXTERRCTL_DISABLE:
                if ((td->td_pflags2 & TDP2_UEXTERR) == 0)
                        return (EINVAL);
                td->td_pflags2 &= ~TDP2_UEXTERR;
                return (0);
        case EXTERRCTL_UD:
                /*
                 * Important: this code must always return EINVAL and never any
                 * extended error, for testing purposes.
                 */
                /* FALLTHROUGH */
        default:
                return (EINVAL);
        }
}

int
exterr_set(int eerror, int category, const char *mmsg, uint64ptr_t pp1,
    uint64ptr_t pp2, int line)
{
        struct thread *td;

        td = curthread;
        if ((td->td_pflags2 & TDP2_UEXTERR) != 0) {
                td->td_pflags2 |= TDP2_EXTERR;
                td->td_kexterr.error = eerror;
                td->td_kexterr.cat = category;
                td->td_kexterr.msg = mmsg;
                td->td_kexterr.p1 = pp1;
                td->td_kexterr.p2 = pp2;
                td->td_kexterr.src_line = line;
        }
        return (eerror);
}

int
exterr_set_from(const struct kexterr *ke)
{
        struct thread *td;

        td = curthread;
        if ((td->td_pflags2 & TDP2_UEXTERR) != 0) {
                td->td_pflags2 |= TDP2_EXTERR;
                td->td_kexterr = *ke;
        }
        return (td->td_kexterr.error);
}

void
exterr_clear(struct kexterr *ke)
{
        memset(ke, 0, sizeof(*ke));
}

#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>

void
exterr_db_print(struct kexterr *ke)
{
        db_printf("errno %d cat %d msg %s p1 %#jx p2 %#jx line %d\n",
            ke->error, ke->cat, ke->msg == NULL ? "<none>" : ke->msg,
            (uintmax_t)ke->p1, (uintmax_t)ke->p2, ke->src_line);
}
#endif