/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2017 Mellanox Technologies, Ltd.
 * 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 unmodified, 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 ``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 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.
 */
#ifndef _LINUXKPI_LINUX_FILE_H_
#define _LINUXKPI_LINUX_FILE_H_

#include <sys/param.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/refcount.h>
#include <sys/capsicum.h>
#include <sys/proc.h>

#include <linux/fs.h>
#include <linux/slab.h>

#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/cleanup.h>

struct linux_file;

#undef file

extern const struct fileops linuxfileops;

static inline struct linux_file *
linux_fget(unsigned int fd)
{
        struct file *file;

        /* lookup file pointer by file descriptor index */
        if (fget_unlocked(curthread, fd, &cap_no_rights, &file) != 0)
                return (NULL);

        /* check if file handle really belongs to us */
        if (file->f_data == NULL ||
            file->f_ops != &linuxfileops) {
                fdrop(file, curthread);
                return (NULL);
        }
        return ((struct linux_file *)file->f_data);
}

extern void linux_file_free(struct linux_file *filp);

static inline void
fput(struct linux_file *filp)
{
        if (refcount_release(filp->_file == NULL ?
            &filp->f_count : &filp->_file->f_count)) {
                linux_file_free(filp);
        }
}

static inline unsigned int
file_count(struct linux_file *filp)
{
        return (filp->_file == NULL ?
            filp->f_count : filp->_file->f_count);
}

static inline void
put_unused_fd(unsigned int fd)
{
        struct file *file;

        if (fget_unlocked(curthread, fd, &cap_no_rights, &file) != 0) {
                return;
        }
        /*
         * NOTE: We should only get here when the "fd" has not been
         * installed, so no need to free the associated Linux file
         * structure.
         */
        fdclose(curthread, file, fd);

        /* drop extra reference */
        fdrop(file, curthread);
}

static inline void
fd_install(unsigned int fd, struct linux_file *filp)
{
        struct file *file;

        if (fget_unlocked(curthread, fd, &cap_no_rights, &file) != 0) {
                filp->_file = NULL;
        } else {
                filp->_file = file;
                finit(file, filp->f_mode, DTYPE_DEV, filp, &linuxfileops);

                /* transfer reference count from "filp" to "file" */
                while (refcount_release(&filp->f_count) == 0)
                        refcount_acquire(&file->f_count);
        }

        /* drop the extra reference */
        fput(filp);
}

static inline int
get_unused_fd(void)
{
        struct file *file;
        int error;
        int fd;

        error = falloc(curthread, &file, &fd, 0);
        if (error)
                return -error;
        /* drop the extra reference */
        fdrop(file, curthread);
        return fd;
}

static inline int
get_unused_fd_flags(int flags)
{
        struct file *file;
        int error;
        int fd;

        error = falloc(curthread, &file, &fd, flags);
        if (error)
                return -error;
        /* drop the extra reference */
        fdrop(file, curthread);
        return fd;
}

extern struct linux_file *linux_file_alloc(void);

static inline struct linux_file *
alloc_file(int mode, const struct file_operations *fops)
{
        struct linux_file *filp;

        filp = linux_file_alloc();
        filp->f_op = fops;
        filp->f_mode = mode;

        return (filp);
}

struct fd {
        struct linux_file *linux_file;
};

static inline void fdput(struct fd fd)
{
        fput(fd.linux_file);
}

static inline struct fd fdget(unsigned int fd)
{
        struct linux_file *f = linux_fget(fd);
        return (struct fd){f};
}

#define file            linux_file
#define fget(...)       linux_fget(__VA_ARGS__)

#endif  /* _LINUXKPI_LINUX_FILE_H_ */