/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1994-1995 Søren Schmidt
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dirent.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/inotify.h>
#include <sys/lock.h>
#include <sys/mman.h>
#include <sys/selinfo.h>
#include <sys/pipe.h>
#include <sys/proc.h>
#include <sys/specialfd.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/sysproto.h>
#include <sys/tty.h>
#include <sys/unistd.h>
#include <sys/vnode.h>

#ifdef COMPAT_LINUX32
#include <compat/freebsd32/freebsd32_misc.h>
#include <compat/freebsd32/freebsd32_util.h>
#include <machine/../linux32/linux.h>
#include <machine/../linux32/linux32_proto.h>
#else
#include <machine/../linux/linux.h>
#include <machine/../linux/linux_proto.h>
#endif
#include <compat/linux/linux_misc.h>
#include <compat/linux/linux_util.h>
#include <compat/linux/linux_file.h>

static int      linux_common_open(struct thread *, int, const char *, int, int,
                    enum uio_seg);
static int      linux_do_accessat(struct thread *t, int, const char *, int, int);
static int      linux_getdents_error(struct thread *, int, int);

static struct bsd_to_linux_bitmap seal_bitmap[] = {
        BITMAP_1t1_LINUX(F_SEAL_SEAL),
        BITMAP_1t1_LINUX(F_SEAL_SHRINK),
        BITMAP_1t1_LINUX(F_SEAL_GROW),
        BITMAP_1t1_LINUX(F_SEAL_WRITE),
};

#define MFD_HUGETLB_ENTRY(_size)                                        \
        {                                                               \
                .bsd_value = MFD_HUGE_##_size,                          \
                .linux_value = LINUX_HUGETLB_FLAG_ENCODE_##_size        \
        }
static struct bsd_to_linux_bitmap mfd_bitmap[] = {
        BITMAP_1t1_LINUX(MFD_CLOEXEC),
        BITMAP_1t1_LINUX(MFD_ALLOW_SEALING),
        BITMAP_1t1_LINUX(MFD_HUGETLB),
        MFD_HUGETLB_ENTRY(64KB),
        MFD_HUGETLB_ENTRY(512KB),
        MFD_HUGETLB_ENTRY(1MB),
        MFD_HUGETLB_ENTRY(2MB),
        MFD_HUGETLB_ENTRY(8MB),
        MFD_HUGETLB_ENTRY(16MB),
        MFD_HUGETLB_ENTRY(32MB),
        MFD_HUGETLB_ENTRY(256MB),
        MFD_HUGETLB_ENTRY(512MB),
        MFD_HUGETLB_ENTRY(1GB),
        MFD_HUGETLB_ENTRY(2GB),
        MFD_HUGETLB_ENTRY(16GB),
};
#undef MFD_HUGETLB_ENTRY

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_creat(struct thread *td, struct linux_creat_args *args)
{

        return (kern_openat(td, AT_FDCWD, args->path, UIO_USERSPACE,
            O_WRONLY | O_CREAT | O_TRUNC, args->mode));
}
#endif

int
linux_common_openflags(int l_flags)
{
        int bsd_flags;

        bsd_flags = 0;
        switch (l_flags & LINUX_O_ACCMODE) {
        case LINUX_O_WRONLY:
                bsd_flags |= O_WRONLY;
                break;
        case LINUX_O_RDWR:
                bsd_flags |= O_RDWR;
                break;
        default:
                bsd_flags |= O_RDONLY;
        }
        if (l_flags & LINUX_O_NDELAY)
                bsd_flags |= O_NONBLOCK;
        if (l_flags & LINUX_O_APPEND)
                bsd_flags |= O_APPEND;
        if (l_flags & LINUX_O_SYNC)
                bsd_flags |= O_FSYNC;
        if (l_flags & LINUX_O_CLOEXEC)
                bsd_flags |= O_CLOEXEC;
        if (l_flags & LINUX_O_NONBLOCK)
                bsd_flags |= O_NONBLOCK;
        if (l_flags & LINUX_O_ASYNC)
                bsd_flags |= O_ASYNC;
        if (l_flags & LINUX_O_CREAT)
                bsd_flags |= O_CREAT;
        if (l_flags & LINUX_O_TRUNC)
                bsd_flags |= O_TRUNC;
        if (l_flags & LINUX_O_EXCL)
                bsd_flags |= O_EXCL;
        if (l_flags & LINUX_O_NOCTTY)
                bsd_flags |= O_NOCTTY;
        if (l_flags & LINUX_O_DIRECT)
                bsd_flags |= O_DIRECT;
        if (l_flags & LINUX_O_NOFOLLOW)
                bsd_flags |= O_NOFOLLOW;
        if (l_flags & LINUX_O_DIRECTORY)
                bsd_flags |= O_DIRECTORY;
        if (l_flags & LINUX_O_PATH)
                bsd_flags |= O_PATH;
        /* XXX LINUX_O_NOATIME: unable to be easily implemented. */
        return (bsd_flags);
}

static int
linux_common_open(struct thread *td, int dirfd, const char *path, int l_flags,
    int mode, enum uio_seg seg)
{
        struct proc *p = td->td_proc;
        struct file *fp;
        int fd;
        int bsd_flags, error;

        bsd_flags = linux_common_openflags(l_flags);
        error = kern_openat(td, dirfd, path, seg, bsd_flags, mode);
        if (error != 0) {
                if (error == EMLINK)
                        error = ELOOP;
                goto done;
        }
        if (p->p_flag & P_CONTROLT)
                goto done;
        if (bsd_flags & O_NOCTTY)
                goto done;

        /*
         * XXX In between kern_openat() and fget(), another process
         * having the same filedesc could use that fd without
         * checking below.
        */
        fd = td->td_retval[0];
        if (fget(td, fd, &cap_ioctl_rights, &fp) == 0) {
                if (fp->f_type != DTYPE_VNODE) {
                        fdrop(fp, td);
                        goto done;
                }
                sx_slock(&proctree_lock);
                PROC_LOCK(p);
                if (SESS_LEADER(p) && !(p->p_flag & P_CONTROLT)) {
                        PROC_UNLOCK(p);
                        sx_sunlock(&proctree_lock);
                        /* XXXPJD: Verify if TIOCSCTTY is allowed. */
                        (void) fo_ioctl(fp, TIOCSCTTY, (caddr_t) 0,
                            td->td_ucred, td);
                } else {
                        PROC_UNLOCK(p);
                        sx_sunlock(&proctree_lock);
                }
                fdrop(fp, td);
        }

done:
        return (error);
}

int
linux_openat(struct thread *td, struct linux_openat_args *args)
{
        int dfd;

        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->dfd;
        return (linux_common_open(td, dfd, args->filename, args->flags,
            args->mode, UIO_USERSPACE));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_open(struct thread *td, struct linux_open_args *args)
{

        return (linux_common_open(td, AT_FDCWD, args->path, args->flags,
            args->mode, UIO_USERSPACE));
}
#endif

int
linux_name_to_handle_at(struct thread *td,
    struct linux_name_to_handle_at_args *args)
{
        static const l_int valid_flags = (LINUX_AT_SYMLINK_FOLLOW |
            LINUX_AT_EMPTY_PATH);
        static const l_uint fh_size = sizeof(fhandle_t);

        fhandle_t fh;
        l_uint fh_bytes;
        l_int mount_id;
        int error, fd, bsd_flags;

        if (args->flags & ~valid_flags)
                return (EINVAL);

        fd = args->dirfd;
        if (fd == LINUX_AT_FDCWD)
                fd = AT_FDCWD;

        bsd_flags = 0;
        if (!(args->flags & LINUX_AT_SYMLINK_FOLLOW))
                bsd_flags |= AT_SYMLINK_NOFOLLOW;
        if ((args->flags & LINUX_AT_EMPTY_PATH) != 0)
                bsd_flags |= AT_EMPTY_PATH;

        error = kern_getfhat(td, bsd_flags, fd, args->name,
            UIO_USERSPACE, &fh, UIO_SYSSPACE);
        if (error != 0)
                return (error);

        /* Emit mount_id -- required before EOVERFLOW case. */
        mount_id = (fh.fh_fsid.val[0] ^ fh.fh_fsid.val[1]);
        error = copyout(&mount_id, args->mnt_id, sizeof(mount_id));
        if (error != 0)
                return (error);

        /* Check if there is room for handle. */
        error = copyin(&args->handle->handle_bytes, &fh_bytes,
            sizeof(fh_bytes));
        if (error != 0)
                return (error);

        if (fh_bytes < fh_size) {
                error = copyout(&fh_size, &args->handle->handle_bytes,
                    sizeof(fh_size));
                if (error == 0)
                        error = EOVERFLOW;
                return (error);
        }

        /* Emit handle. */
        mount_id = 0;
        /*
         * We don't use handle_type for anything yet, but initialize a known
         * value.
         */
        error = copyout(&mount_id, &args->handle->handle_type,
            sizeof(mount_id));
        if (error != 0)
                return (error);

        error = copyout(&fh, &args->handle->f_handle,
            sizeof(fh));
        return (error);
}

int
linux_open_by_handle_at(struct thread *td,
    struct linux_open_by_handle_at_args *args)
{
        l_uint fh_bytes;
        int bsd_flags, error;

        error = copyin(&args->handle->handle_bytes, &fh_bytes,
            sizeof(fh_bytes));
        if (error != 0)
                return (error);

        if (fh_bytes < sizeof(fhandle_t))
                return (EINVAL);

        bsd_flags = linux_common_openflags(args->flags);
        return (kern_fhopen(td, (void *)&args->handle->f_handle, bsd_flags));
}

int
linux_lseek(struct thread *td, struct linux_lseek_args *args)
{

        return (kern_lseek(td, args->fdes, args->off, args->whence));
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_llseek(struct thread *td, struct linux_llseek_args *args)
{
        int error;
        off_t off;

        off = (args->olow) | (((off_t) args->ohigh) << 32);

        error = kern_lseek(td, args->fd, off, args->whence);
        if (error != 0)
                return (error);

        error = copyout(td->td_retval, args->res, sizeof(off_t));
        if (error != 0)
                return (error);

        td->td_retval[0] = 0;
        return (0);
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

/*
 * Note that linux_getdents(2) and linux_getdents64(2) have the same
 * arguments. They only differ in the definition of struct dirent they
 * operate on.
 * Note that linux_readdir(2) is a special case of linux_getdents(2)
 * where count is always equals 1, meaning that the buffer is one
 * dirent-structure in size and that the code can't handle more anyway.
 * Note that linux_readdir(2) can't be implemented by means of linux_getdents(2)
 * as in case when the *dent buffer size is equal to 1 linux_getdents(2) will
 * trash user stack.
 */

static int
linux_getdents_error(struct thread *td, int fd, int err)
{
        struct vnode *vp;
        struct file *fp;
        int error;

        /* Linux return ENOTDIR in case when fd is not a directory. */
        error = getvnode(td, fd, &cap_read_rights, &fp);
        if (error != 0)
                return (error);
        vp = fp->f_vnode;
        if (vp->v_type != VDIR) {
                fdrop(fp, td);
                return (ENOTDIR);
        }
        fdrop(fp, td);
        return (err);
}

struct l_dirent {
        l_ulong         d_ino;
        l_off_t         d_off;
        l_ushort        d_reclen;
        char            d_name[LINUX_NAME_MAX + 1];
};

struct l_dirent64 {
        uint64_t        d_ino;
        int64_t         d_off;
        l_ushort        d_reclen;
        u_char          d_type;
        char            d_name[LINUX_NAME_MAX + 1];
};

/*
 * Linux uses the last byte in the dirent buffer to store d_type,
 * at least glibc-2.7 requires it. That is why l_dirent is padded with 2 bytes.
 */
#define LINUX_RECLEN(namlen)                                            \
    roundup(offsetof(struct l_dirent, d_name) + (namlen) + 2, sizeof(l_ulong))

#define LINUX_RECLEN64(namlen)                                          \
    roundup(offsetof(struct l_dirent64, d_name) + (namlen) + 1,         \
    sizeof(uint64_t))

/*
 * Do kern_getdirentries() and then skip over any invalid entries.
 * (Repeat, if there are no valid entries.)
 * Adjust bufp and lenp.
 */
static int
linux_getdirentries(struct thread *td, int fd, caddr_t *bufp, int buflen,
    off_t *basep, int *lenp)
{
        struct dirent *bdp;
        caddr_t buf;
        int error, len;

        /* Loop around until a valid entry is found or at EOF. */
        for (;;) {
                error = kern_getdirentries(td, fd, *bufp, buflen,
                    basep, NULL, UIO_SYSSPACE);
                if (error != 0)
                        return (error);
                len = td->td_retval[0];
                if (len == 0) {
                        *lenp = 0;
                        return (0);
                }
                buf = *bufp;
                while (len > 0) {
                        bdp = (struct dirent *)buf;
                        if (bdp->d_fileno != 0) {
                                *bufp = buf;
                                *lenp = len;
                                return (0);
                        }
                        buf += bdp->d_reclen;
                        len -= bdp->d_reclen;
                }
        }
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_getdents(struct thread *td, struct linux_getdents_args *args)
{
        struct dirent *bdp;
        caddr_t inp, buf, bufsav;       /* BSD-format */
        int len, reclen;                /* BSD-format */
        caddr_t outp;                   /* Linux-format */
        int resid, linuxreclen;         /* Linux-format */
        caddr_t lbuf;                   /* Linux-format */
        off_t base;
        struct l_dirent *linux_dirent;
        int buflen, error;
        size_t retval;

        buflen = min(roundup2(args->count, DEV_BSIZE), MAXBSIZE);
        bufsav = buf = malloc(buflen, M_LINUX, M_WAITOK);

        error = linux_getdirentries(td, args->fd, &buf, buflen,
            &base, &len);
        if (error != 0) {
                error = linux_getdents_error(td, args->fd, error);
                goto out1;
        }

        lbuf = malloc(LINUX_RECLEN(LINUX_NAME_MAX), M_LINUX, M_WAITOK | M_ZERO);

        inp = buf;
        outp = (caddr_t)args->dent;
        resid = args->count;
        retval = 0;

        while (len > 0) {
                bdp = (struct dirent *) inp;
                reclen = bdp->d_reclen;
                /* Copy a valid entry out. */
                if (bdp->d_fileno != 0) {
                        linuxreclen = LINUX_RECLEN(bdp->d_namlen);
                        /*
                         * No more space in the user supplied dirent buffer.
                         * Return EINVAL.
                         */
                        if (resid < linuxreclen) {
                                error = EINVAL;
                                goto out;
                        }

                        linux_dirent = (struct l_dirent*)lbuf;
                        linux_dirent->d_ino = bdp->d_fileno;
                        linux_dirent->d_off = bdp->d_off;
                        linux_dirent->d_reclen = linuxreclen;
                        /*
                         * Copy d_type to last byte of l_dirent buffer
                         */
                        lbuf[linuxreclen - 1] = bdp->d_type;
                        strlcpy(linux_dirent->d_name, bdp->d_name,
                            linuxreclen - offsetof(struct l_dirent, d_name)-1);
                        error = copyout(linux_dirent, outp, linuxreclen);
                        if (error != 0)
                                goto out;
                        retval += linuxreclen;
                        outp += linuxreclen;
                        resid -= linuxreclen;
                }

                inp += reclen;
                base += reclen;
                len -= reclen;

        }
        td->td_retval[0] = retval;

out:
        free(lbuf, M_LINUX);
out1:
        free(bufsav, M_LINUX);
        return (error);
}
#endif

int
linux_getdents64(struct thread *td, struct linux_getdents64_args *args)
{
        struct dirent *bdp;
        caddr_t inp, buf, bufsav;       /* BSD-format */
        int len, reclen;                /* BSD-format */
        caddr_t outp;                   /* Linux-format */
        int resid, linuxreclen;         /* Linux-format */
        off_t base;
        struct l_dirent64 *linux_dirent64;
        int buflen, error;
        size_t retval;

        buflen = min(roundup2(args->count, DEV_BSIZE), MAXBSIZE);
        bufsav = buf = malloc(buflen, M_LINUX, M_WAITOK);

        error = linux_getdirentries(td, args->fd, &buf, buflen,
            &base, &len);
        if (error != 0) {
                error = linux_getdents_error(td, args->fd, error);
                goto out1;
        }

        linux_dirent64 = malloc(LINUX_RECLEN64(LINUX_NAME_MAX), M_LINUX,
            M_WAITOK | M_ZERO);

        inp = buf;
        outp = (caddr_t)args->dirent;
        resid = args->count;
        retval = 0;

        while (len > 0) {
                bdp = (struct dirent *) inp;
                reclen = bdp->d_reclen;
                /* Copy a valid entry out. */
                if (bdp->d_fileno != 0) {
                        linuxreclen = LINUX_RECLEN64(bdp->d_namlen);
                        /*
                         * No more space in the user supplied dirent buffer.
                         * Return EINVAL.
                         */
                        if (resid < linuxreclen) {
                                error = EINVAL;
                                goto out;
                        }

                        linux_dirent64->d_ino = bdp->d_fileno;
                        linux_dirent64->d_off = bdp->d_off;
                        linux_dirent64->d_reclen = linuxreclen;
                        linux_dirent64->d_type = bdp->d_type;
                        strlcpy(linux_dirent64->d_name, bdp->d_name,
                            linuxreclen - offsetof(struct l_dirent64, d_name));
                        error = copyout(linux_dirent64, outp, linuxreclen);
                        if (error != 0)
                                goto out;
                        retval += linuxreclen;
                        outp += linuxreclen;
                        resid -= linuxreclen;
                }

                inp += reclen;
                base += reclen;
                len -= reclen;

        }
        td->td_retval[0] = retval;

out:
        free(linux_dirent64, M_LINUX);
out1:
        free(bufsav, M_LINUX);
        return (error);
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_readdir(struct thread *td, struct linux_readdir_args *args)
{
        struct dirent *bdp;
        caddr_t buf, bufsav;            /* BSD-format */
        int linuxreclen;                /* Linux-format */
        off_t base;
        struct l_dirent *linux_dirent;  /* Linux-format */
        int buflen, error, len;

        buflen = DEV_BSIZE;
        bufsav = buf = malloc(buflen, M_LINUX, M_WAITOK);

        error = linux_getdirentries(td, args->fd, &buf, buflen,
            &base, &len);
        if (error != 0) {
                error = linux_getdents_error(td, args->fd, error);
                goto out;
        }
        if (len == 0)
                goto out;

        linux_dirent = malloc(LINUX_RECLEN(LINUX_NAME_MAX), M_LINUX,
            M_WAITOK | M_ZERO);

        bdp = (struct dirent *) buf;
        linuxreclen = LINUX_RECLEN(bdp->d_namlen);

        linux_dirent->d_ino = bdp->d_fileno;
        linux_dirent->d_off = bdp->d_off;
        linux_dirent->d_reclen = bdp->d_namlen;
        strlcpy(linux_dirent->d_name, bdp->d_name,
            linuxreclen - offsetof(struct l_dirent, d_name));
        error = copyout(linux_dirent, args->dent, linuxreclen);
        if (error == 0)
                td->td_retval[0] = linuxreclen;

        free(linux_dirent, M_LINUX);
out:
        free(bufsav, M_LINUX);
        return (error);
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

/*
 * These exist mainly for hooks for doing /compat/linux translation.
 */

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_access(struct thread *td, struct linux_access_args *args)
{

        /* Linux convention. */
        if (args->amode & ~(F_OK | X_OK | W_OK | R_OK))
                return (EINVAL);

        return (kern_accessat(td, AT_FDCWD, args->path, UIO_USERSPACE, 0,
            args->amode));
}
#endif

static int
linux_do_accessat(struct thread *td, int ldfd, const char *filename,
    int amode, int flags)
{
        int dfd;

        /* Linux convention. */
        if (amode & ~(F_OK | X_OK | W_OK | R_OK))
                return (EINVAL);

        dfd = (ldfd == LINUX_AT_FDCWD) ? AT_FDCWD : ldfd;
        return (kern_accessat(td, dfd, filename, UIO_USERSPACE, flags, amode));
}

int
linux_faccessat(struct thread *td, struct linux_faccessat_args *args)
{

        return (linux_do_accessat(td, args->dfd, args->filename, args->amode,
            0));
}

int
linux_faccessat2(struct thread *td, struct linux_faccessat2_args *args)
{
        int flags, unsupported;

        unsupported = args->flags & ~(LINUX_AT_EACCESS | LINUX_AT_EMPTY_PATH  |
            LINUX_AT_SYMLINK_NOFOLLOW);
        if (unsupported != 0) {
                linux_msg(td, "faccessat2 unsupported flag 0x%x", unsupported);
                return (EINVAL);
        }

        flags = (args->flags & LINUX_AT_EACCESS) == 0 ? 0 :
            AT_EACCESS;
        flags |= (args->flags & LINUX_AT_EMPTY_PATH) == 0 ? 0 :
            AT_EMPTY_PATH;
        flags |= (args->flags & LINUX_AT_SYMLINK_NOFOLLOW) == 0 ? 0 :
            AT_SYMLINK_NOFOLLOW;
        return (linux_do_accessat(td, args->dfd, args->filename, args->amode,
            flags));
}


#ifdef LINUX_LEGACY_SYSCALLS
int
linux_unlink(struct thread *td, struct linux_unlink_args *args)
{
        int error;
        struct stat st;

        error = kern_funlinkat(td, AT_FDCWD, args->path, FD_NONE,
            UIO_USERSPACE, 0, 0);
        if (error == EPERM) {
                /* Introduce POSIX noncompliant behaviour of Linux */
                if (kern_statat(td, 0, AT_FDCWD, args->path,
                    UIO_USERSPACE, &st) == 0) {
                        if (S_ISDIR(st.st_mode))
                                error = EISDIR;
                }
        }

        return (error);
}
#endif

static int
linux_unlinkat_impl(struct thread *td, enum uio_seg pathseg, const char *path,
    int dfd, struct linux_unlinkat_args *args)
{
        struct stat st;
        int error;

        if (args->flag & LINUX_AT_REMOVEDIR)
                error = kern_frmdirat(td, dfd, path, FD_NONE, pathseg, 0);
        else
                error = kern_funlinkat(td, dfd, path, FD_NONE, pathseg, 0, 0);
        if (error == EPERM && !(args->flag & LINUX_AT_REMOVEDIR)) {
                /* Introduce POSIX noncompliant behaviour of Linux */
                if (kern_statat(td, AT_SYMLINK_NOFOLLOW, dfd, path,
                    pathseg, &st) == 0 && S_ISDIR(st.st_mode))
                        error = EISDIR;
        }
        return (error);
}

int
linux_unlinkat(struct thread *td, struct linux_unlinkat_args *args)
{
        int dfd;

        if (args->flag & ~LINUX_AT_REMOVEDIR)
                return (EINVAL);
        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->dfd;
        return (linux_unlinkat_impl(td, UIO_USERSPACE, args->pathname,
            dfd, args));
}

int
linux_chdir(struct thread *td, struct linux_chdir_args *args)
{

        return (kern_chdir(td, args->path, UIO_USERSPACE));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_chmod(struct thread *td, struct linux_chmod_args *args)
{

        return (kern_fchmodat(td, AT_FDCWD, args->path, UIO_USERSPACE,
            args->mode, 0));
}
#endif

int
linux_fchmodat(struct thread *td, struct linux_fchmodat_args *args)
{
        int dfd;

        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->dfd;
        return (kern_fchmodat(td, dfd, args->filename, UIO_USERSPACE,
            args->mode, 0));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_mkdir(struct thread *td, struct linux_mkdir_args *args)
{

        return (kern_mkdirat(td, AT_FDCWD, args->path, UIO_USERSPACE, args->mode));
}
#endif

int
linux_mkdirat(struct thread *td, struct linux_mkdirat_args *args)
{
        int dfd;

        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->dfd;
        return (kern_mkdirat(td, dfd, args->pathname, UIO_USERSPACE, args->mode));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_rmdir(struct thread *td, struct linux_rmdir_args *args)
{

        return (kern_frmdirat(td, AT_FDCWD, args->path, FD_NONE,
            UIO_USERSPACE, 0));
}

int
linux_rename(struct thread *td, struct linux_rename_args *args)
{

        return (kern_renameat(td, AT_FDCWD, args->from, AT_FDCWD,
            args->to, UIO_USERSPACE, 0));
}
#endif

int
linux_renameat(struct thread *td, struct linux_renameat_args *args)
{
        struct linux_renameat2_args renameat2_args = {
            .olddfd = args->olddfd,
            .oldname = args->oldname,
            .newdfd = args->newdfd,
            .newname = args->newname,
            .flags = 0
        };

        return (linux_renameat2(td, &renameat2_args));
}

int
linux_renameat2(struct thread *td, struct linux_renameat2_args *args)
{
        int olddfd, newdfd;
        u_int atflags;

        atflags = 0;
        if ((args->flags & ~(LINUX_RENAME_EXCHANGE |
            LINUX_RENAME_NOREPLACE | LINUX_RENAME_WHITEOUT)) != 0)
                return (EINVAL);
        if ((args->flags & LINUX_RENAME_EXCHANGE) != 0 &&
            (args->flags & (LINUX_RENAME_NOREPLACE |
            LINUX_RENAME_WHITEOUT)) != 0)
                return (EINVAL);
        if ((args->flags & LINUX_RENAME_NOREPLACE) != 0) {
                if ((args->flags & (LINUX_RENAME_EXCHANGE |
                    LINUX_RENAME_WHITEOUT)) != 0)
                        return (EINVAL);
                args->flags &= ~LINUX_RENAME_NOREPLACE;
                atflags |= AT_RENAME_NOREPLACE;
        }

        if (args->flags != 0) {
                /*
                 * This spams the console on Ubuntu Focal.
                 *
                 * What's needed here is a general mechanism to let
                 * users know about missing features without hogging
                 * the system.
                 */
#if 0
                linux_msg(td, "renameat2 unsupported flags %#x",
                    args->flags);
#endif
                return (EINVAL);
        }

        olddfd = (args->olddfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->olddfd;
        newdfd = (args->newdfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->newdfd;
        return (kern_renameat(td, olddfd, args->oldname, newdfd,
            args->newname, UIO_USERSPACE, atflags));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_symlink(struct thread *td, struct linux_symlink_args *args)
{

        return (kern_symlinkat(td, args->path, AT_FDCWD, args->to,
            UIO_USERSPACE));
}
#endif

int
linux_symlinkat(struct thread *td, struct linux_symlinkat_args *args)
{
        int dfd;

        dfd = (args->newdfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->newdfd;
        return (kern_symlinkat(td, args->oldname, dfd, args->newname,
            UIO_USERSPACE));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_readlink(struct thread *td, struct linux_readlink_args *args)
{

        if (args->count <= 0)
                return (EINVAL);

        return (kern_readlinkat(td, AT_FDCWD, args->name, UIO_USERSPACE,
            args->buf, UIO_USERSPACE, args->count));
}
#endif

int
linux_readlinkat(struct thread *td, struct linux_readlinkat_args *args)
{
        int dfd;

        if (args->bufsiz <= 0)
                return (EINVAL);

        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->dfd;
        return (kern_readlinkat(td, dfd, args->path, UIO_USERSPACE,
            args->buf, UIO_USERSPACE, args->bufsiz));
}

int
linux_truncate(struct thread *td, struct linux_truncate_args *args)
{

        return (kern_truncate(td, args->path, UIO_USERSPACE, args->length));
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_truncate64(struct thread *td, struct linux_truncate64_args *args)
{
        off_t length;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        length = PAIR32TO64(off_t, args->length);
#else
        length = args->length;
#endif

        return (kern_truncate(td, args->path, UIO_USERSPACE, length));
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

int
linux_ftruncate(struct thread *td, struct linux_ftruncate_args *args)
{

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

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_ftruncate64(struct thread *td, struct linux_ftruncate64_args *args)
{
        off_t length;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        length = PAIR32TO64(off_t, args->length);
#else
        length = args->length;
#endif

        return (kern_ftruncate(td, args->fd, length));
}
#endif

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_link(struct thread *td, struct linux_link_args *args)
{

        return (kern_linkat(td, AT_FDCWD, AT_FDCWD, args->path, args->to,
            UIO_USERSPACE, AT_SYMLINK_FOLLOW));
}
#endif

int
linux_linkat(struct thread *td, struct linux_linkat_args *args)
{
        int olddfd, newdfd, flag;

        if (args->flag & ~(LINUX_AT_SYMLINK_FOLLOW | LINUX_AT_EMPTY_PATH))
                return (EINVAL);

        flag = (args->flag & LINUX_AT_SYMLINK_FOLLOW) != 0 ? AT_SYMLINK_FOLLOW :
            0;
        flag |= (args->flag & LINUX_AT_EMPTY_PATH) != 0 ? AT_EMPTY_PATH : 0;

        olddfd = (args->olddfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->olddfd;
        newdfd = (args->newdfd == LINUX_AT_FDCWD) ? AT_FDCWD : args->newdfd;
        return (kern_linkat(td, olddfd, newdfd, args->oldname,
            args->newname, UIO_USERSPACE, flag));
}

int
linux_fdatasync(struct thread *td, struct linux_fdatasync_args *uap)
{

        return (kern_fsync(td, uap->fd, false));
}

int
linux_sync_file_range(struct thread *td, struct linux_sync_file_range_args *uap)
{
        off_t nbytes, offset;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        nbytes = PAIR32TO64(off_t, uap->nbytes);
        offset = PAIR32TO64(off_t, uap->offset);
#else
        nbytes = uap->nbytes;
        offset = uap->offset;
#endif

        if (offset < 0 || nbytes < 0 ||
            (uap->flags & ~(LINUX_SYNC_FILE_RANGE_WAIT_BEFORE |
            LINUX_SYNC_FILE_RANGE_WRITE |
            LINUX_SYNC_FILE_RANGE_WAIT_AFTER)) != 0) {
                return (EINVAL);
        }

        return (kern_fsync(td, uap->fd, false));
}

int
linux_pread(struct thread *td, struct linux_pread_args *uap)
{
        struct vnode *vp;
        off_t offset;
        int error;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        offset = PAIR32TO64(off_t, uap->offset);
#else
        offset = uap->offset;
#endif

        error = kern_pread(td, uap->fd, uap->buf, uap->nbyte, offset);
        if (error == 0) {
                /* This seems to violate POSIX but Linux does it. */
                error = fgetvp(td, uap->fd, &cap_pread_rights, &vp);
                if (error != 0)
                        return (error);
                if (vp->v_type == VDIR)
                        error = EISDIR;
                vrele(vp);
        }
        return (error);
}

int
linux_pwrite(struct thread *td, struct linux_pwrite_args *uap)
{
        off_t offset;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        offset = PAIR32TO64(off_t, uap->offset);
#else
        offset = uap->offset;
#endif

        return (linux_enobufs2eagain(td, uap->fd,
            kern_pwrite(td, uap->fd, uap->buf, uap->nbyte, offset)));
}

#define HALF_LONG_BITS ((sizeof(l_long) * NBBY / 2))

static inline off_t
pos_from_hilo(unsigned long high, unsigned long low)
{

        return (((off_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
}

int
linux_preadv(struct thread *td, struct linux_preadv_args *uap)
{
        struct uio *auio;
        int error;
        off_t offset;

        /*
         * According http://man7.org/linux/man-pages/man2/preadv.2.html#NOTES
         * pos_l and pos_h, respectively, contain the
         * low order and high order 32 bits of offset.
         */
        offset = pos_from_hilo(uap->pos_h, uap->pos_l);
        if (offset < 0)
                return (EINVAL);
#ifdef COMPAT_LINUX32
        error = freebsd32_copyinuio(PTRIN(uap->vec), uap->vlen, &auio);
#else
        error = copyinuio(uap->vec, uap->vlen, &auio);
#endif
        if (error != 0)
                return (error);
        error = kern_preadv(td, uap->fd, auio, offset);
        freeuio(auio);
        return (error);
}

int
linux_pwritev(struct thread *td, struct linux_pwritev_args *uap)
{
        struct uio *auio;
        int error;
        off_t offset;

        /*
         * According http://man7.org/linux/man-pages/man2/pwritev.2.html#NOTES
         * pos_l and pos_h, respectively, contain the
         * low order and high order 32 bits of offset.
         */
        offset = pos_from_hilo(uap->pos_h, uap->pos_l);
        if (offset < 0)
                return (EINVAL);
#ifdef COMPAT_LINUX32
        error = freebsd32_copyinuio(PTRIN(uap->vec), uap->vlen, &auio);
#else
        error = copyinuio(uap->vec, uap->vlen, &auio);
#endif
        if (error != 0)
                return (error);
        error = kern_pwritev(td, uap->fd, auio, offset);
        freeuio(auio);
        return (linux_enobufs2eagain(td, uap->fd, error));
}

int
linux_mount(struct thread *td, struct linux_mount_args *args)
{
        struct mntarg *ma = NULL;
        char *fstypename, *mntonname, *mntfromname, *data;
        int error, fsflags;

        fstypename = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        mntonname = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        mntfromname = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        data = NULL;
        error = copyinstr(args->filesystemtype, fstypename, MNAMELEN - 1,
            NULL);
        if (error != 0)
                goto out;
        if (args->specialfile != NULL) {
                error = copyinstr(args->specialfile, mntfromname, MNAMELEN - 1, NULL);
                if (error != 0)
                        goto out;
        } else {
                mntfromname[0] = '\0';
        }
        error = copyinstr(args->dir, mntonname, MNAMELEN - 1, NULL);
        if (error != 0)
                goto out;

        if (strcmp(fstypename, "ext2") == 0) {
                strcpy(fstypename, "ext2fs");
        } else if (strcmp(fstypename, "proc") == 0) {
                strcpy(fstypename, "linprocfs");
        } else if (strcmp(fstypename, "vfat") == 0) {
                strcpy(fstypename, "msdosfs");
        } else if (strcmp(fstypename, "fuse") == 0 ||
            strncmp(fstypename, "fuse.", 5) == 0) {
                char *fuse_options, *fuse_option, *fuse_name;

                strcpy(mntfromname, "/dev/fuse");
                strcpy(fstypename, "fusefs");
                data = malloc(MNAMELEN, M_TEMP, M_WAITOK);
                error = copyinstr(args->data, data, MNAMELEN - 1, NULL);
                if (error != 0)
                        goto out;

                fuse_options = data;
                while ((fuse_option = strsep(&fuse_options, ",")) != NULL) {
                        fuse_name = strsep(&fuse_option, "=");
                        if (fuse_name == NULL || fuse_option == NULL)
                                goto out;
                        ma = mount_arg(ma, fuse_name, fuse_option, -1);
                }

                /*
                 * The FUSE server uses Linux errno values instead of FreeBSD
                 * ones; add a flag to tell fuse(4) to do errno translation.
                 */
                ma = mount_arg(ma, "linux_errnos", "1", -1);
        }

        fsflags = 0;

        /*
         * Linux SYNC flag is not included; the closest equivalent
         * FreeBSD has is !ASYNC, which is our default.
         */
        if (args->rwflag & LINUX_MS_RDONLY)
                fsflags |= MNT_RDONLY;
        if (args->rwflag & LINUX_MS_NOSUID)
                fsflags |= MNT_NOSUID;
        if (args->rwflag & LINUX_MS_NOEXEC)
                fsflags |= MNT_NOEXEC;
        if (args->rwflag & LINUX_MS_REMOUNT)
                fsflags |= MNT_UPDATE;

        ma = mount_arg(ma, "fstype", fstypename, -1);
        ma = mount_arg(ma, "fspath", mntonname, -1);
        ma = mount_arg(ma, "from", mntfromname, -1);
        error = kernel_mount(ma, fsflags);
out:
        free(fstypename, M_TEMP);
        free(mntonname, M_TEMP);
        free(mntfromname, M_TEMP);
        free(data, M_TEMP);
        return (error);
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_oldumount(struct thread *td, struct linux_oldumount_args *args)
{

        return (kern_unmount(td, args->path, 0));
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_umount(struct thread *td, struct linux_umount_args *args)
{
        uint64_t flags;

        flags = 0;
        if ((args->flags & LINUX_MNT_FORCE) != 0) {
                args->flags &= ~LINUX_MNT_FORCE;
                flags |= MNT_FORCE;
        }
        if (args->flags != 0) {
                linux_msg(td, "unsupported umount2 flags %#x", args->flags);
                return (EINVAL);
        }

        return (kern_unmount(td, args->path, flags));
}
#endif

/*
 * fcntl family of syscalls
 */

struct l_flock {
        l_short         l_type;
        l_short         l_whence;
        l_off_t         l_start;
        l_off_t         l_len;
        l_pid_t         l_pid;
}
#if defined(__amd64__) && defined(COMPAT_LINUX32)
__packed
#endif
;

static void
linux_to_bsd_flock(struct l_flock *linux_flock, struct flock *bsd_flock)
{
        switch (linux_flock->l_type) {
        case LINUX_F_RDLCK:
                bsd_flock->l_type = F_RDLCK;
                break;
        case LINUX_F_WRLCK:
                bsd_flock->l_type = F_WRLCK;
                break;
        case LINUX_F_UNLCK:
                bsd_flock->l_type = F_UNLCK;
                break;
        default:
                bsd_flock->l_type = -1;
                break;
        }
        bsd_flock->l_whence = linux_flock->l_whence;
        bsd_flock->l_start = (off_t)linux_flock->l_start;
        bsd_flock->l_len = (off_t)linux_flock->l_len;
        bsd_flock->l_pid = (pid_t)linux_flock->l_pid;
        bsd_flock->l_sysid = 0;
}

static void
bsd_to_linux_flock(struct flock *bsd_flock, struct l_flock *linux_flock)
{
        switch (bsd_flock->l_type) {
        case F_RDLCK:
                linux_flock->l_type = LINUX_F_RDLCK;
                break;
        case F_WRLCK:
                linux_flock->l_type = LINUX_F_WRLCK;
                break;
        case F_UNLCK:
                linux_flock->l_type = LINUX_F_UNLCK;
                break;
        }
        linux_flock->l_whence = bsd_flock->l_whence;
        linux_flock->l_start = (l_off_t)bsd_flock->l_start;
        linux_flock->l_len = (l_off_t)bsd_flock->l_len;
        linux_flock->l_pid = (l_pid_t)bsd_flock->l_pid;
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
struct l_flock64 {
        l_short         l_type;
        l_short         l_whence;
        l_loff_t        l_start;
        l_loff_t        l_len;
        l_pid_t         l_pid;
}
#if defined(__amd64__) && defined(COMPAT_LINUX32)
__packed
#endif
;

static void
linux_to_bsd_flock64(struct l_flock64 *linux_flock, struct flock *bsd_flock)
{
        switch (linux_flock->l_type) {
        case LINUX_F_RDLCK:
                bsd_flock->l_type = F_RDLCK;
                break;
        case LINUX_F_WRLCK:
                bsd_flock->l_type = F_WRLCK;
                break;
        case LINUX_F_UNLCK:
                bsd_flock->l_type = F_UNLCK;
                break;
        default:
                bsd_flock->l_type = -1;
                break;
        }
        bsd_flock->l_whence = linux_flock->l_whence;
        bsd_flock->l_start = (off_t)linux_flock->l_start;
        bsd_flock->l_len = (off_t)linux_flock->l_len;
        bsd_flock->l_pid = (pid_t)linux_flock->l_pid;
        bsd_flock->l_sysid = 0;
}

static void
bsd_to_linux_flock64(struct flock *bsd_flock, struct l_flock64 *linux_flock)
{
        switch (bsd_flock->l_type) {
        case F_RDLCK:
                linux_flock->l_type = LINUX_F_RDLCK;
                break;
        case F_WRLCK:
                linux_flock->l_type = LINUX_F_WRLCK;
                break;
        case F_UNLCK:
                linux_flock->l_type = LINUX_F_UNLCK;
                break;
        }
        linux_flock->l_whence = bsd_flock->l_whence;
        linux_flock->l_start = (l_loff_t)bsd_flock->l_start;
        linux_flock->l_len = (l_loff_t)bsd_flock->l_len;
        linux_flock->l_pid = (l_pid_t)bsd_flock->l_pid;
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

static int
fcntl_common(struct thread *td, struct linux_fcntl_args *args)
{
        struct l_flock linux_flock;
        struct flock bsd_flock;
        struct pipe *fpipe;
        struct file *fp;
        long arg;
        int error, result;

        switch (args->cmd) {
        case LINUX_F_DUPFD:
                return (kern_fcntl(td, args->fd, F_DUPFD, args->arg));

        case LINUX_F_GETFD:
                return (kern_fcntl(td, args->fd, F_GETFD, 0));

        case LINUX_F_SETFD:
                return (kern_fcntl(td, args->fd, F_SETFD, args->arg));

        case LINUX_F_GETFL:
                error = kern_fcntl(td, args->fd, F_GETFL, 0);
                result = td->td_retval[0];
                td->td_retval[0] = 0;
                if (result & O_RDONLY)
                        td->td_retval[0] |= LINUX_O_RDONLY;
                if (result & O_WRONLY)
                        td->td_retval[0] |= LINUX_O_WRONLY;
                if (result & O_RDWR)
                        td->td_retval[0] |= LINUX_O_RDWR;
                if (result & O_NDELAY)
                        td->td_retval[0] |= LINUX_O_NONBLOCK;
                if (result & O_APPEND)
                        td->td_retval[0] |= LINUX_O_APPEND;
                if (result & O_FSYNC)
                        td->td_retval[0] |= LINUX_O_SYNC;
                if (result & O_ASYNC)
                        td->td_retval[0] |= LINUX_O_ASYNC;
#ifdef LINUX_O_NOFOLLOW
                if (result & O_NOFOLLOW)
                        td->td_retval[0] |= LINUX_O_NOFOLLOW;
#endif
#ifdef LINUX_O_DIRECT
                if (result & O_DIRECT)
                        td->td_retval[0] |= LINUX_O_DIRECT;
#endif
                return (error);

        case LINUX_F_SETFL:
                arg = 0;
                if (args->arg & LINUX_O_NDELAY)
                        arg |= O_NONBLOCK;
                if (args->arg & LINUX_O_APPEND)
                        arg |= O_APPEND;
                if (args->arg & LINUX_O_SYNC)
                        arg |= O_FSYNC;
                if (args->arg & LINUX_O_ASYNC)
                        arg |= O_ASYNC;
#ifdef LINUX_O_NOFOLLOW
                if (args->arg & LINUX_O_NOFOLLOW)
                        arg |= O_NOFOLLOW;
#endif
#ifdef LINUX_O_DIRECT
                if (args->arg & LINUX_O_DIRECT)
                        arg |= O_DIRECT;
#endif
                return (kern_fcntl(td, args->fd, F_SETFL, arg));

        case LINUX_F_GETLK:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock(&linux_flock, &bsd_flock);
                error = kern_fcntl(td, args->fd, F_GETLK, (intptr_t)&bsd_flock);
                if (error)
                        return (error);
                bsd_to_linux_flock(&bsd_flock, &linux_flock);
                return (copyout(&linux_flock, (void *)args->arg,
                    sizeof(linux_flock)));

        case LINUX_F_SETLK:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock(&linux_flock, &bsd_flock);
                return (kern_fcntl(td, args->fd, F_SETLK,
                    (intptr_t)&bsd_flock));

        case LINUX_F_SETLKW:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock(&linux_flock, &bsd_flock);
                return (kern_fcntl(td, args->fd, F_SETLKW,
                     (intptr_t)&bsd_flock));

        case LINUX_F_GETOWN:
                return (kern_fcntl(td, args->fd, F_GETOWN, 0));

        case LINUX_F_SETOWN:
                /*
                 * XXX some Linux applications depend on F_SETOWN having no
                 * significant effect for pipes (SIGIO is not delivered for
                 * pipes under Linux-2.2.35 at least).
                 */
                error = fget(td, args->fd,
                    &cap_fcntl_rights, &fp);
                if (error)
                        return (error);
                if (fp->f_type == DTYPE_PIPE) {
                        fdrop(fp, td);
                        return (EINVAL);
                }
                fdrop(fp, td);

                return (kern_fcntl(td, args->fd, F_SETOWN, args->arg));

        case LINUX_F_DUPFD_CLOEXEC:
                return (kern_fcntl(td, args->fd, F_DUPFD_CLOEXEC, args->arg));
        /*
         * Our F_SEAL_* values match Linux one for maximum compatibility.  So we
         * only needed to account for different values for fcntl(2) commands.
         */
        case LINUX_F_GET_SEALS:
                error = kern_fcntl(td, args->fd, F_GET_SEALS, 0);
                if (error != 0)
                        return (error);
                td->td_retval[0] = bsd_to_linux_bits(td->td_retval[0],
                    seal_bitmap, 0);
                return (0);

        case LINUX_F_ADD_SEALS:
                return (kern_fcntl(td, args->fd, F_ADD_SEALS,
                    linux_to_bsd_bits(args->arg, seal_bitmap, 0)));

        case LINUX_F_GETPIPE_SZ:
                error = fget(td, args->fd,
                    &cap_fcntl_rights, &fp);
                if (error != 0)
                        return (error);
                if (fp->f_type != DTYPE_PIPE) {
                        fdrop(fp, td);
                        return (EINVAL);
                }
                fpipe = fp->f_data;
                td->td_retval[0] = fpipe->pipe_buffer.size;
                fdrop(fp, td);
                return (0);

        case LINUX_F_DUPFD_QUERY:
                error = kern_kcmp(td, td->td_proc->p_pid, td->td_proc->p_pid,
                    KCMP_FILE, args->fd, args->arg);
                if (error != 0)
                        return (error);
                td->td_retval[0] = (td->td_retval[0] == 0) ? 1 : 0;
                return (0);

        default:
                linux_msg(td, "unsupported fcntl cmd %d", args->cmd);
                return (EINVAL);
        }
}

int
linux_fcntl(struct thread *td, struct linux_fcntl_args *args)
{

        return (fcntl_common(td, args));
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_fcntl64(struct thread *td, struct linux_fcntl64_args *args)
{
        struct l_flock64 linux_flock;
        struct flock bsd_flock;
        struct linux_fcntl_args fcntl_args;
        int error;

        switch (args->cmd) {
        case LINUX_F_GETLK64:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock64(&linux_flock, &bsd_flock);
                error = kern_fcntl(td, args->fd, F_GETLK, (intptr_t)&bsd_flock);
                if (error)
                        return (error);
                bsd_to_linux_flock64(&bsd_flock, &linux_flock);
                return (copyout(&linux_flock, (void *)args->arg,
                            sizeof(linux_flock)));

        case LINUX_F_SETLK64:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock64(&linux_flock, &bsd_flock);
                return (kern_fcntl(td, args->fd, F_SETLK,
                    (intptr_t)&bsd_flock));

        case LINUX_F_SETLKW64:
                error = copyin((void *)args->arg, &linux_flock,
                    sizeof(linux_flock));
                if (error)
                        return (error);
                linux_to_bsd_flock64(&linux_flock, &bsd_flock);
                return (kern_fcntl(td, args->fd, F_SETLKW,
                    (intptr_t)&bsd_flock));
        }

        fcntl_args.fd = args->fd;
        fcntl_args.cmd = args->cmd;
        fcntl_args.arg = args->arg;
        return (fcntl_common(td, &fcntl_args));
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_chown(struct thread *td, struct linux_chown_args *args)
{

        return (kern_fchownat(td, AT_FDCWD, args->path, UIO_USERSPACE,
            args->uid, args->gid, 0));
}
#endif

int
linux_fchownat(struct thread *td, struct linux_fchownat_args *args)
{
        int dfd, flag, unsupported;

        unsupported = args->flag & ~(LINUX_AT_SYMLINK_NOFOLLOW | LINUX_AT_EMPTY_PATH);
        if (unsupported != 0) {
                linux_msg(td, "fchownat unsupported flag 0x%x", unsupported);
                return (EINVAL);
        }

        flag = (args->flag & LINUX_AT_SYMLINK_NOFOLLOW) == 0 ? 0 :
            AT_SYMLINK_NOFOLLOW;
        flag |= (args->flag & LINUX_AT_EMPTY_PATH) == 0 ? 0 :
            AT_EMPTY_PATH;

        dfd = (args->dfd == LINUX_AT_FDCWD) ? AT_FDCWD :  args->dfd;
        return (kern_fchownat(td, dfd, args->filename, UIO_USERSPACE,
            args->uid, args->gid, flag));
}

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_lchown(struct thread *td, struct linux_lchown_args *args)
{

        return (kern_fchownat(td, AT_FDCWD, args->path, UIO_USERSPACE, args->uid,
            args->gid, AT_SYMLINK_NOFOLLOW));
}
#endif

static int
convert_fadvice(int advice)
{
        switch (advice) {
        case LINUX_POSIX_FADV_NORMAL:
                return (POSIX_FADV_NORMAL);
        case LINUX_POSIX_FADV_RANDOM:
                return (POSIX_FADV_RANDOM);
        case LINUX_POSIX_FADV_SEQUENTIAL:
                return (POSIX_FADV_SEQUENTIAL);
        case LINUX_POSIX_FADV_WILLNEED:
                return (POSIX_FADV_WILLNEED);
        case LINUX_POSIX_FADV_DONTNEED:
                return (POSIX_FADV_DONTNEED);
        case LINUX_POSIX_FADV_NOREUSE:
                return (POSIX_FADV_NOREUSE);
        default:
                return (-1);
        }
}

int
linux_fadvise64(struct thread *td, struct linux_fadvise64_args *args)
{
        off_t offset;
        int advice;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        offset = PAIR32TO64(off_t, args->offset);
#else
        offset = args->offset;
#endif

        advice = convert_fadvice(args->advice);
        if (advice == -1)
                return (EINVAL);
        return (kern_posix_fadvise(td, args->fd, offset, args->len, advice));
}

#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
int
linux_fadvise64_64(struct thread *td, struct linux_fadvise64_64_args *args)
{
        off_t len, offset;
        int advice;

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        len = PAIR32TO64(off_t, args->len);
        offset = PAIR32TO64(off_t, args->offset);
#else
        len = args->len;
        offset = args->offset;
#endif

        advice = convert_fadvice(args->advice);
        if (advice == -1)
                return (EINVAL);
        return (kern_posix_fadvise(td, args->fd, offset, len, advice));
}
#endif /* __i386__ || (__amd64__ && COMPAT_LINUX32) */

#ifdef LINUX_LEGACY_SYSCALLS
int
linux_pipe(struct thread *td, struct linux_pipe_args *args)
{
        int fildes[2];
        int error;

        error = kern_pipe(td, fildes, 0, NULL, NULL);
        if (error != 0)
                return (error);

        error = copyout(fildes, args->pipefds, sizeof(fildes));
        if (error != 0) {
                (void)kern_close(td, fildes[0]);
                (void)kern_close(td, fildes[1]);
        }

        return (error);
}
#endif

int
linux_pipe2(struct thread *td, struct linux_pipe2_args *args)
{
        int fildes[2];
        int error, flags;

        if ((args->flags & ~(LINUX_O_NONBLOCK | LINUX_O_CLOEXEC)) != 0)
                return (EINVAL);

        flags = 0;
        if ((args->flags & LINUX_O_NONBLOCK) != 0)
                flags |= O_NONBLOCK;
        if ((args->flags & LINUX_O_CLOEXEC) != 0)
                flags |= O_CLOEXEC;
        error = kern_pipe(td, fildes, flags, NULL, NULL);
        if (error != 0)
                return (error);

        error = copyout(fildes, args->pipefds, sizeof(fildes));
        if (error != 0) {
                (void)kern_close(td, fildes[0]);
                (void)kern_close(td, fildes[1]);
        }

        return (error);
}

int
linux_dup3(struct thread *td, struct linux_dup3_args *args)
{
        int cmd;
        intptr_t newfd;

        if (args->oldfd == args->newfd)
                return (EINVAL);
        if ((args->flags & ~LINUX_O_CLOEXEC) != 0)
                return (EINVAL);
        if (args->flags & LINUX_O_CLOEXEC)
                cmd = F_DUP2FD_CLOEXEC;
        else
                cmd = F_DUP2FD;

        newfd = args->newfd;
        return (kern_fcntl(td, args->oldfd, cmd, newfd));
}

int
linux_fallocate(struct thread *td, struct linux_fallocate_args *args)
{
        off_t len, offset;

        /*
         * We emulate only posix_fallocate system call for which
         * mode should be 0.
         */
        if (args->mode != 0)
                return (EOPNOTSUPP);

#if defined(__amd64__) && defined(COMPAT_LINUX32)
        len = PAIR32TO64(off_t, args->len);
        offset = PAIR32TO64(off_t, args->offset);
#else
        len = args->len;
        offset = args->offset;
#endif

        return (kern_posix_fallocate(td, args->fd, offset, len));
}

int
linux_copy_file_range(struct thread *td, struct linux_copy_file_range_args
    *args)
{
        l_loff_t inoff, outoff, *inoffp, *outoffp;
        int error, flags;

        /*
         * copy_file_range(2) on Linux doesn't define any flags (yet), so is
         * the native implementation.  Enforce it.
         */
        if (args->flags != 0) {
                linux_msg(td, "copy_file_range unsupported flags 0x%x",
                    args->flags);
                return (EINVAL);
        }
        flags = 0;
        inoffp = outoffp = NULL;
        if (args->off_in != NULL) {
                error = copyin(args->off_in, &inoff, sizeof(l_loff_t));
                if (error != 0)
                        return (error);
                inoffp = &inoff;
        }
        if (args->off_out != NULL) {
                error = copyin(args->off_out, &outoff, sizeof(l_loff_t));
                if (error != 0)
                        return (error);
                outoffp = &outoff;
        }

        error = kern_copy_file_range(td, args->fd_in, inoffp, args->fd_out,
            outoffp, args->len, flags);
        if (error == 0 && args->off_in != NULL)
                error = copyout(inoffp, args->off_in, sizeof(l_loff_t));
        if (error == 0 && args->off_out != NULL)
                error = copyout(outoffp, args->off_out, sizeof(l_loff_t));
        return (error);
}

#define LINUX_MEMFD_PREFIX      "memfd:"

int
linux_memfd_create(struct thread *td, struct linux_memfd_create_args *args)
{
        char memfd_name[LINUX_NAME_MAX + 1];
        int error, flags, shmflags, oflags;

        /*
         * This is our clever trick to avoid the heap allocation to copy in the
         * uname.  We don't really need to go this far out of our way, but it
         * does keep the rest of this function fairly clean as they don't have
         * to worry about cleanup on the way out.
         */
        error = copyinstr(args->uname_ptr,
            memfd_name + sizeof(LINUX_MEMFD_PREFIX) - 1,
            LINUX_NAME_MAX - sizeof(LINUX_MEMFD_PREFIX) - 1, NULL);
        if (error != 0) {
                if (error == ENAMETOOLONG)
                        error = EINVAL;
                return (error);
        }

        memcpy(memfd_name, LINUX_MEMFD_PREFIX, sizeof(LINUX_MEMFD_PREFIX) - 1);
        flags = linux_to_bsd_bits(args->flags, mfd_bitmap, 0);
        if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
            MFD_HUGE_MASK)) != 0)
                return (EINVAL);
        /* Size specified but no HUGETLB. */
        if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0)
                return (EINVAL);
        /* We don't actually support HUGETLB. */
        if ((flags & MFD_HUGETLB) != 0)
                return (ENOSYS);
        oflags = O_RDWR;
        shmflags = SHM_GROW_ON_WRITE;
        if ((flags & MFD_CLOEXEC) != 0)
                oflags |= O_CLOEXEC;
        if ((flags & MFD_ALLOW_SEALING) != 0)
                shmflags |= SHM_ALLOW_SEALING;
        return (kern_shm_open2(td, SHM_ANON, oflags, 0, shmflags, NULL,
            memfd_name, NULL));
}

int
linux_splice(struct thread *td, struct linux_splice_args *args)
{

        linux_msg(td, "syscall splice not really implemented");

        /*
         * splice(2) is documented to return EINVAL in various circumstances;
         * returning it instead of ENOSYS should hint the caller to use fallback
         * instead.
         */
        return (EINVAL);
}

int
linux_close_range(struct thread *td, struct linux_close_range_args *args)
{
        u_int flags = 0;

        /*
         * Implementing close_range(CLOSE_RANGE_UNSHARE) allows Linux to
         * unshare filedesc table of the calling thread from others threads
         * in a thread group (i.e., process in the FreeBSD) or others processes,
         * which shares the same table, before closing the files. FreeBSD does
         * not have compatible unsharing mechanism due to the fact that sharing
         * process resources, including filedesc table, is at thread level in the
         * Linux, while in the FreeBSD it is at the process level.
         * Return EINVAL for now if the CLOSE_RANGE_UNSHARE flag is specified
         * until this new Linux API stabilizes.
         */

        if ((args->flags & ~(LINUX_CLOSE_RANGE_CLOEXEC)) != 0)
                return (EINVAL);
        if (args->first > args->last)
                return (EINVAL);
        if ((args->flags & LINUX_CLOSE_RANGE_CLOEXEC) != 0)
                flags |= CLOSE_RANGE_CLOEXEC;
        return (kern_close_range(td, flags, args->first, args->last));
}

int
linux_enobufs2eagain(struct thread *td, int fd, int error)
{
        struct file *fp;

        if (error != ENOBUFS)
                return (error);
        if (fget(td, fd, &cap_no_rights, &fp) != 0)
                return (error);
        if (fp->f_type == DTYPE_SOCKET && (fp->f_flag & FNONBLOCK) != 0)
                error = EAGAIN;
        fdrop(fp, td);
        return (error);
}

int
linux_write(struct thread *td, struct linux_write_args *args)
{
        struct write_args bargs = {
                .fd     = args->fd,
                .buf    = args->buf,
                .nbyte  = args->nbyte,
        };

        return (linux_enobufs2eagain(td, args->fd, sys_write(td, &bargs)));
}

int
linux_writev(struct thread *td, struct linux_writev_args *args)
{
        struct uio *auio;
        int error;

#ifdef COMPAT_LINUX32
        error = freebsd32_copyinuio(PTRIN(args->iovp), args->iovcnt, &auio);
#else
        error = copyinuio(args->iovp, args->iovcnt, &auio);
#endif
        if (error != 0)
                return (error);
        error = kern_writev(td, args->fd, auio);
        freeuio(auio);
        return (linux_enobufs2eagain(td, args->fd, error));
}

static int
linux_inotify_init_flags(int l_flags)
{
        int bsd_flags;

        if ((l_flags & ~(LINUX_IN_CLOEXEC | LINUX_IN_NONBLOCK)) != 0)
                linux_msg(NULL, "inotify_init1 unsupported flags 0x%x",
                    l_flags);

        bsd_flags = 0;
        if ((l_flags & LINUX_IN_CLOEXEC) != 0)
                bsd_flags |= O_CLOEXEC;
        if ((l_flags & LINUX_IN_NONBLOCK) != 0)
                bsd_flags |= O_NONBLOCK;
        return (bsd_flags);
}

static int
inotify_init_common(struct thread *td, int flags)
{
        struct specialfd_inotify si;

        si.flags = linux_inotify_init_flags(flags);
        return (kern_specialfd(td, SPECIALFD_INOTIFY, &si));
}

#if defined(__i386__) || defined(__amd64__)
int
linux_inotify_init(struct thread *td, struct linux_inotify_init_args *args)
{
        return (inotify_init_common(td, 0));
}
#endif

int
linux_inotify_init1(struct thread *td, struct linux_inotify_init1_args *args)
{
        return (inotify_init_common(td, args->flags));
}

/*
 * The native implementation uses the same values for inotify events as
 * libinotify, which gives us binary compatibility with Linux.  This simplifies
 * the shim implementation a lot, as otherwise we would have to handle read(2)
 * calls on inotify descriptors and translate events to Linux's ABI.
 */
_Static_assert(LINUX_IN_ACCESS == IN_ACCESS,
    "IN_ACCESS mismatch");
_Static_assert(LINUX_IN_MODIFY == IN_MODIFY,
    "IN_MODIFY mismatch");
_Static_assert(LINUX_IN_ATTRIB == IN_ATTRIB,
    "IN_ATTRIB mismatch");
_Static_assert(LINUX_IN_CLOSE_WRITE == IN_CLOSE_WRITE,
    "IN_CLOSE_WRITE mismatch");
_Static_assert(LINUX_IN_CLOSE_NOWRITE == IN_CLOSE_NOWRITE,
    "IN_CLOSE_NOWRITE mismatch");
_Static_assert(LINUX_IN_OPEN == IN_OPEN,
    "IN_OPEN mismatch");
_Static_assert(LINUX_IN_MOVED_FROM == IN_MOVED_FROM,
    "IN_MOVED_FROM mismatch");
_Static_assert(LINUX_IN_MOVED_TO == IN_MOVED_TO,
    "IN_MOVED_TO mismatch");
_Static_assert(LINUX_IN_CREATE == IN_CREATE,
    "IN_CREATE mismatch");
_Static_assert(LINUX_IN_DELETE == IN_DELETE,
    "IN_DELETE mismatch");
_Static_assert(LINUX_IN_DELETE_SELF == IN_DELETE_SELF,
    "IN_DELETE_SELF mismatch");
_Static_assert(LINUX_IN_MOVE_SELF == IN_MOVE_SELF,
    "IN_MOVE_SELF mismatch");

_Static_assert(LINUX_IN_UNMOUNT == IN_UNMOUNT,
    "IN_UNMOUNT mismatch");
_Static_assert(LINUX_IN_Q_OVERFLOW == IN_Q_OVERFLOW,
    "IN_Q_OVERFLOW mismatch");
_Static_assert(LINUX_IN_IGNORED == IN_IGNORED,
    "IN_IGNORED mismatch");

_Static_assert(LINUX_IN_ISDIR == IN_ISDIR,
    "IN_ISDIR mismatch");
_Static_assert(LINUX_IN_ONLYDIR == IN_ONLYDIR,
    "IN_ONLYDIR mismatch");
_Static_assert(LINUX_IN_DONT_FOLLOW == IN_DONT_FOLLOW,
    "IN_DONT_FOLLOW mismatch");
_Static_assert(LINUX_IN_MASK_CREATE == IN_MASK_CREATE,
    "IN_MASK_CREATE mismatch");
_Static_assert(LINUX_IN_MASK_ADD == IN_MASK_ADD,
    "IN_MASK_ADD mismatch");
_Static_assert(LINUX_IN_ONESHOT == IN_ONESHOT,
    "IN_ONESHOT mismatch");
_Static_assert(LINUX_IN_EXCL_UNLINK == IN_EXCL_UNLINK,
    "IN_EXCL_UNLINK mismatch");

static int
linux_inotify_watch_flags(int l_flags)
{
        if ((l_flags & ~(LINUX_IN_ALL_EVENTS | LINUX_IN_ALL_FLAGS)) != 0) {
                linux_msg(NULL, "inotify_add_watch unsupported flags 0x%x",
                    l_flags);
        }

        return (l_flags);
}

int
linux_inotify_add_watch(struct thread *td,
    struct linux_inotify_add_watch_args *args)
{
        return (kern_inotify_add_watch(args->fd, AT_FDCWD, args->pathname,
            linux_inotify_watch_flags(args->mask), td));
}

int
linux_inotify_rm_watch(struct thread *td,
    struct linux_inotify_rm_watch_args *args)
{
        return (kern_inotify_rm_watch(args->fd, args->wd, td));
}