/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2007-2009 Google Inc. and Amit Singh
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * 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.
 * * Neither the name of Google Inc. 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 COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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.
 *
 * Copyright (C) 2005 Csaba Henk.
 * All rights reserved.
 *
 * Copyright (c) 2019 The FreeBSD Foundation
 *
 * Portions of this software were developed by BFF Storage Systems, LLC under
 * sponsorship from the FreeBSD Foundation.
 *
 * 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 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 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/counter.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/sdt.h>
#include <sys/sysctl.h>

#include "fuse.h"
#include "fuse_file.h"
#include "fuse_internal.h"
#include "fuse_io.h"
#include "fuse_ipc.h"
#include "fuse_node.h"

MALLOC_DEFINE(M_FUSE_FILEHANDLE, "fuse_filefilehandle", "FUSE file handle");

SDT_PROVIDER_DECLARE(fusefs);
/* 
 * Fuse trace probe:
 * arg0: verbosity.  Higher numbers give more verbose messages
 * arg1: Textual message
 */
SDT_PROBE_DEFINE2(fusefs, , file, trace, "int", "char*");

static counter_u64_t fuse_fh_count;

SYSCTL_COUNTER_U64(_vfs_fusefs_stats, OID_AUTO, filehandle_count, CTLFLAG_RD,
    &fuse_fh_count, "number of open FUSE filehandles");

/* Get the FUFH type for a particular access mode */
static inline fufh_type_t
fflags_2_fufh_type(int fflags)
{
        if ((fflags & FREAD) && (fflags & FWRITE))
                return FUFH_RDWR;
        else if (fflags & (FWRITE))
                return FUFH_WRONLY;
        else if (fflags & (FREAD))
                return FUFH_RDONLY;
        else if (fflags & (FEXEC))
                return FUFH_EXEC;
        else
                panic("FUSE: What kind of a flag is this (%x)?", fflags);
}

int
fuse_filehandle_open(struct vnode *vp, int a_mode,
    struct fuse_filehandle **fufhp, struct thread *td, struct ucred *cred)
{
        struct mount *mp = vnode_mount(vp);
        struct fuse_dispatcher fdi;
        const struct fuse_open_out default_foo = {
                .fh = 0,
                .open_flags = FOPEN_KEEP_CACHE,
                .padding = 0
        };
        struct fuse_open_in *foi = NULL;
        const struct fuse_open_out *foo;
        fufh_type_t fufh_type;
        int err = 0;
        int oflags = 0;
        int op = FUSE_OPEN;
        int relop = FUSE_RELEASE;

        fufh_type = fflags_2_fufh_type(a_mode);
        oflags = fufh_type_2_fflags(fufh_type);

        if (vnode_isdir(vp)) {
                op = FUSE_OPENDIR;
                relop = FUSE_RELEASEDIR;
                /* vn_open_vnode already rejects FWRITE on directories */
                MPASS(fufh_type == FUFH_RDONLY || fufh_type == FUFH_EXEC);
        }
        fdisp_init(&fdi, sizeof(*foi));
        if (fsess_not_impl(mp, op)) {
                /* The operation implicitly succeeds */
                foo = &default_foo;
        } else {
                fdisp_make_vp(&fdi, op, vp, td, cred);

                foi = fdi.indata;
                foi->flags = oflags;

                err = fdisp_wait_answ(&fdi);
                if (err == ENOSYS) {
                        /* The operation implicitly succeeds */
                        foo = &default_foo;
                        fsess_set_notimpl(mp, op);
                        fsess_set_notimpl(mp, relop);
                        err = 0;
                } else if (err) {
                        SDT_PROBE2(fusefs, , file, trace, 1,
                                "OUCH ... daemon didn't give fh");
                        if (err == ENOENT)
                                fuse_internal_vnode_disappear(vp);
                        goto out;
                } else {
                        foo = fdi.answ;
                        fsess_set_impl(mp, op);
                }
        }

        fuse_filehandle_init(vp, fufh_type, fufhp, td, cred, foo);
        fuse_vnode_open(vp, foo->open_flags, td);

out:
        if (foi)
                fdisp_destroy(&fdi);
        return err;
}

int
fuse_filehandle_close(struct vnode *vp, struct fuse_filehandle *fufh,
    struct thread *td, struct ucred *cred)
{
        struct mount *mp = vnode_mount(vp);
        struct fuse_dispatcher fdi;
        struct fuse_release_in *fri;

        int err = 0;
        int op = FUSE_RELEASE;

        ASSERT_VOP_ELOCKED(vp, __func__);

        if (fuse_isdeadfs(vp)) {
                goto out;
        }
        if (vnode_isdir(vp))
                op = FUSE_RELEASEDIR;

        if (fsess_not_impl(mp, op))
                goto out;

        fdisp_init(&fdi, sizeof(*fri));
        fdisp_make_vp(&fdi, op, vp, td, cred);
        fri = fdi.indata;
        fri->fh = fufh->fh_id;
        fri->flags = fufh_type_2_fflags(fufh->fufh_type);
        /* 
         * If the file has a POSIX lock then we're supposed to set lock_owner.
         * If not, then lock_owner is undefined.  So we may as well always set
         * it.
         */
        fri->lock_owner = td->td_proc->p_pid;

        err = fdisp_wait_answ(&fdi);
        fdisp_destroy(&fdi);

out:
        counter_u64_add(fuse_fh_count, -1);
        LIST_REMOVE(fufh, next);
        free(fufh, M_FUSE_FILEHANDLE);

        return err;
}

/*
 * Check for a valid file handle, first the type requested, but if that
 * isn't valid, try for FUFH_RDWR.
 * Return true if there is any file handle with the correct credentials and
 * a fufh type that includes the provided one.
 * A pid of 0 means "don't care"
 */
bool
fuse_filehandle_validrw(struct vnode *vp, int mode,
        struct ucred *cred, pid_t pid)
{
        struct fuse_vnode_data *fvdat = VTOFUD(vp);
        struct fuse_filehandle *fufh;
        fufh_type_t fufh_type = fflags_2_fufh_type(mode);

        /* 
         * Unlike fuse_filehandle_get, we want to search for a filehandle with
         * the exact cred, and no fallback
         */
        LIST_FOREACH(fufh, &fvdat->handles, next) {
                if (fufh->fufh_type == fufh_type &&
                    fufh->uid == cred->cr_uid &&
                    fufh->gid == cred->cr_rgid &&
                    (pid == 0 || fufh->pid == pid))
                        return true;
        }

        if (fufh_type == FUFH_EXEC)
                return false;

        /* Fallback: find a RDWR list entry with the right cred */
        LIST_FOREACH(fufh, &fvdat->handles, next) {
                if (fufh->fufh_type == FUFH_RDWR &&
                    fufh->uid == cred->cr_uid &&
                    fufh->gid == cred->cr_rgid &&
                    (pid == 0 || fufh->pid == pid))
                        return true;
        }

        return false;
}

int
fuse_filehandle_get(struct vnode *vp, int fflag,
    struct fuse_filehandle **fufhp, struct ucred *cred, pid_t pid)
{
        struct fuse_vnode_data *fvdat = VTOFUD(vp);
        struct fuse_filehandle *fufh;
        fufh_type_t fufh_type;

        fufh_type = fflags_2_fufh_type(fflag);
        /* cred can be NULL for in-kernel clients */
        if (cred == NULL)
                goto fallback;

        LIST_FOREACH(fufh, &fvdat->handles, next) {
                if (fufh->fufh_type == fufh_type &&
                    fufh->uid == cred->cr_uid &&
                    fufh->gid == cred->cr_rgid &&
                    (pid == 0 || fufh->pid == pid))
                        goto found;
        }

fallback:
        /* Fallback: find a list entry with the right flags */
        LIST_FOREACH(fufh, &fvdat->handles, next) {
                if (fufh->fufh_type == fufh_type)
                        break;
        }

        if (fufh == NULL)
                return EBADF;

found:
        if (fufhp != NULL)
                *fufhp = fufh;
        return 0;
}

/* Get a file handle with any kind of flags */
int
fuse_filehandle_get_anyflags(struct vnode *vp,
    struct fuse_filehandle **fufhp, struct ucred *cred, pid_t pid)
{
        struct fuse_vnode_data *fvdat = VTOFUD(vp);
        struct fuse_filehandle *fufh;

        if (cred == NULL)
                goto fallback;

        LIST_FOREACH(fufh, &fvdat->handles, next) {
                if (fufh->uid == cred->cr_uid &&
                    fufh->gid == cred->cr_rgid &&
                    (pid == 0 || fufh->pid == pid))
                        goto found;
        }

fallback:
        /* Fallback: find any list entry */
        fufh = LIST_FIRST(&fvdat->handles);

        if (fufh == NULL)
                return EBADF;

found:
        if (fufhp != NULL)
                *fufhp = fufh;
        return 0;
}

int
fuse_filehandle_getrw(struct vnode *vp, int fflag,
    struct fuse_filehandle **fufhp, struct ucred *cred, pid_t pid)
{
        int err;

        err = fuse_filehandle_get(vp, fflag, fufhp, cred, pid);
        if (err)
                err = fuse_filehandle_get(vp, FREAD | FWRITE, fufhp, cred, pid);
        return err;
}

void
fuse_filehandle_init(struct vnode *vp, fufh_type_t fufh_type,
    struct fuse_filehandle **fufhp, struct thread *td, const struct ucred *cred,
    const struct fuse_open_out *foo)
{
        struct fuse_vnode_data *fvdat = VTOFUD(vp);
        struct fuse_filehandle *fufh;

        fufh = malloc(sizeof(struct fuse_filehandle), M_FUSE_FILEHANDLE,
                M_WAITOK);
        MPASS(fufh != NULL);
        fufh->fh_id = foo->fh;
        fufh->fufh_type = fufh_type;
        fufh->gid = cred->cr_rgid;
        fufh->uid = cred->cr_uid;
        fufh->pid = td->td_proc->p_pid;
        fufh->fuse_open_flags = foo->open_flags;
        if (!FUFH_IS_VALID(fufh)) {
                panic("FUSE: init: invalid filehandle id (type=%d)", fufh_type);
        }
        LIST_INSERT_HEAD(&fvdat->handles, fufh, next);
        if (fufhp != NULL)
                *fufhp = fufh;

        counter_u64_add(fuse_fh_count, 1);

        if (foo->open_flags & FOPEN_DIRECT_IO) {
                ASSERT_VOP_ELOCKED(vp, __func__);
                VTOFUD(vp)->flag |= FN_DIRECTIO;
                fuse_io_invalbuf(vp, td);
        } else {
                if ((foo->open_flags & FOPEN_KEEP_CACHE) == 0)
                        fuse_io_invalbuf(vp, td);
                /*
                 * XXX Update the flag without the lock for now.  See
                 * https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=293088
                 */
                VTOFUD(vp)->flag &= ~FN_DIRECTIO;
        }

}

void
fuse_file_init(void)
{
        fuse_fh_count = counter_u64_alloc(M_WAITOK);
}

void
fuse_file_destroy(void)
{
        counter_u64_free(fuse_fh_count);
}