/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2018 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_FS_H_
#define	_LINUXKPI_LINUX_FS_H_

#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/semaphore.h>
#include <linux/spinlock.h>
#include <linux/dcache.h>
#include <linux/capability.h>
#include <linux/wait_bit.h>
#include <linux/kernel.h>
#include <linux/mutex.h>

struct module;
struct kiocb;
struct iovec;
struct dentry;
struct page;
struct file_lock;
struct pipe_inode_info;
struct vm_area_struct;
struct poll_table_struct;
struct files_struct;
struct pfs_node;
struct linux_cdev;

#define	inode	vnode
#define	i_cdev	v_rdev
#define	i_private v_data

#define	S_IRUGO	(S_IRUSR | S_IRGRP | S_IROTH)
#define	S_IWUGO	(S_IWUSR | S_IWGRP | S_IWOTH)

typedef struct files_struct *fl_owner_t;

struct file_operations;

struct linux_file_wait_queue {
	struct wait_queue wq;
	struct wait_queue_head *wqh;
	atomic_t state;
#define	LINUX_FWQ_STATE_INIT 0
#define	LINUX_FWQ_STATE_NOT_READY 1
#define	LINUX_FWQ_STATE_QUEUED 2
#define	LINUX_FWQ_STATE_READY 3
#define	LINUX_FWQ_STATE_MAX 4
};

struct linux_file {
	struct file	*_file;
	const struct file_operations	*f_op;
	void		*private_data;
	int		f_flags;
	int		f_mode;	/* Just starting mode. */
	struct dentry	*f_dentry;
	struct dentry	f_dentry_store;
	struct selinfo	f_selinfo;
	struct sigio	*f_sigio;
	struct vnode	*f_vnode;
#define	f_inode	f_vnode
	volatile u_int	f_count;

	/* anonymous shmem object */
	vm_object_t	f_shmem;

	/* kqfilter support */
	int		f_kqflags;
#define	LINUX_KQ_FLAG_HAS_READ (1 << 0)
#define	LINUX_KQ_FLAG_HAS_WRITE (1 << 1)
#define	LINUX_KQ_FLAG_NEED_READ (1 << 2)
#define	LINUX_KQ_FLAG_NEED_WRITE (1 << 3)
	/* protects f_selinfo.si_note */
	spinlock_t	f_kqlock;
	struct linux_file_wait_queue f_wait_queue;

	/* pointer to associated character device, if any */
	struct linux_cdev *f_cdev;

	struct rcu_head	rcu;
};

#define	file		linux_file
#define	fasync_struct	sigio *

#define	fasync_helper(fd, filp, on, queue)				\
({									\
	if ((on))							\
		*(queue) = &(filp)->f_sigio;				\
	else								\
		*(queue) = NULL;					\
	0;								\
})

#define	kill_fasync(queue, sig, pollstat)				\
do {									\
	if (*(queue) != NULL)						\
		pgsigio(*(queue), (sig), 0);				\
} while (0)

typedef int (*filldir_t)(void *, const char *, int, off_t, u64, unsigned);

struct file_operations {
	struct module *owner;
	ssize_t (*read)(struct linux_file *, char __user *, size_t, off_t *);
	ssize_t (*write)(struct linux_file *, const char __user *, size_t, off_t *);
	unsigned int (*poll) (struct linux_file *, struct poll_table_struct *);
	long (*unlocked_ioctl)(struct linux_file *, unsigned int, unsigned long);
	long (*compat_ioctl)(struct linux_file *, unsigned int, unsigned long);
	int (*mmap)(struct linux_file *, struct vm_area_struct *);
	int (*open)(struct inode *, struct file *);
	int (*release)(struct inode *, struct linux_file *);
	int (*fasync)(int, struct linux_file *, int);

/* Although not supported in FreeBSD, to align with Linux code
 * we are adding llseek() only when it is mapped to no_llseek which returns
 * an illegal seek error
 */
	off_t (*llseek)(struct linux_file *, off_t, int);
#if 0
	/* We do not support these methods.  Don't permit them to compile. */
	loff_t (*llseek)(struct file *, loff_t, int);
	ssize_t (*aio_read)(struct kiocb *, const struct iovec *,
	    unsigned long, loff_t);
	ssize_t (*aio_write)(struct kiocb *, const struct iovec *,
	    unsigned long, loff_t);
	int (*readdir)(struct file *, void *, filldir_t);
	int (*ioctl)(struct inode *, struct file *, unsigned int,
	    unsigned long);
	int (*flush)(struct file *, fl_owner_t id);
	int (*fsync)(struct file *, struct dentry *, int datasync);
	int (*aio_fsync)(struct kiocb *, int datasync);
	int (*lock)(struct file *, int, struct file_lock *);
	ssize_t (*sendpage)(struct file *, struct page *, int, size_t,
	    loff_t *, int);
	unsigned long (*get_unmapped_area)(struct file *, unsigned long,
	    unsigned long, unsigned long, unsigned long);
	int (*check_flags)(int);
	int (*flock)(struct file *, int, struct file_lock *);
	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
	    loff_t *, size_t, unsigned int);
	ssize_t (*splice_read)(struct file *, loff_t *,
	    struct pipe_inode_info *, size_t, unsigned int);
	int (*setlease)(struct file *, long, struct file_lock **);
#endif
};
#define	fops_get(fops)		(fops)
#define	replace_fops(f, fops)	((f)->f_op = (fops))

#define	FMODE_READ	FREAD
#define	FMODE_WRITE	FWRITE
#define	FMODE_EXEC	FEXEC
#define	FMODE_UNSIGNED_OFFSET	0x2000
int __register_chrdev(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name,
    const struct file_operations *fops);
int __register_chrdev_p(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name,
    const struct file_operations *fops, uid_t uid,
    gid_t gid, int mode);
void __unregister_chrdev(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name);

static inline void
unregister_chrdev(unsigned int major, const char *name)
{

	__unregister_chrdev(major, 0, 256, name);
}

static inline int
register_chrdev(unsigned int major, const char *name,
    const struct file_operations *fops)
{

	return (__register_chrdev(major, 0, 256, name, fops));
}

static inline int
register_chrdev_p(unsigned int major, const char *name,
    const struct file_operations *fops, uid_t uid, gid_t gid, int mode)
{

	return (__register_chrdev_p(major, 0, 256, name, fops, uid, gid, mode));
}

static inline int
register_chrdev_region(dev_t dev, unsigned range, const char *name)
{

	return 0;
}

static inline void
unregister_chrdev_region(dev_t dev, unsigned range)
{

	return;
}

static inline int
alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
			const char *name)
{

	return 0;
}

/* No current support for seek op in FreeBSD */
static inline int
nonseekable_open(struct inode *inode, struct file *filp)
{
	return 0;
}

static inline int
simple_open(struct inode *inode, struct file *filp)
{
	filp->private_data = inode->i_private;
	return 0;
}

extern unsigned int linux_iminor(struct inode *);
#define	iminor(...) linux_iminor(__VA_ARGS__)

static inline struct linux_file *
get_file(struct linux_file *f)
{

	refcount_acquire(f->_file == NULL ? &f->f_count : &f->_file->f_count);
	return (f);
}

static inline bool
get_file_rcu(struct linux_file *f)
{
	return (refcount_acquire_if_not_zero(
	    f->_file == NULL ? &f->f_count : &f->_file->f_count));
}

static inline struct inode *
igrab(struct inode *inode)
{
	int error;

	error = vget(inode, 0);
	if (error)
		return (NULL);

	return (inode);
}

static inline void
iput(struct inode *inode)
{

	vrele(inode);
}

static inline loff_t
no_llseek(struct file *file, loff_t offset, int whence)
{

	return (-ESPIPE);
}

static inline loff_t
default_llseek(struct file *file, loff_t offset, int whence)
{
	return (no_llseek(file, offset, whence));
}

static inline loff_t
generic_file_llseek(struct file *file, loff_t offset, int whence)
{
	return (no_llseek(file, offset, whence));
}

static inline loff_t
noop_llseek(struct linux_file *file, loff_t offset, int whence)
{

	return (file->_file->f_offset);
}

static inline struct vnode *
file_inode(const struct linux_file *file)
{

	return (file->f_vnode);
}

static inline int
call_mmap(struct linux_file *file, struct vm_area_struct *vma)
{

	return (file->f_op->mmap(file, vma));
}

static inline void
i_size_write(struct inode *inode, loff_t i_size)
{
}

/*
 * simple_read_from_buffer: copy data from kernel-space origin
 * buffer into user-space destination buffer
 *
 * @dest: destination buffer
 * @read_size: number of bytes to be transferred
 * @ppos: starting transfer position pointer
 * @orig: origin buffer
 * @buf_size: size of destination and origin buffers
 *
 * Return value:
 * On success, total bytes copied with *ppos incremented accordingly.
 * On failure, negative value.
 */
static inline ssize_t
simple_read_from_buffer(void __user *dest, size_t read_size, loff_t *ppos,
    void *orig, size_t buf_size)
{
	void *read_pos = ((char *) orig) + *ppos;
	size_t buf_remain = buf_size - *ppos;
	ssize_t num_read;

	if (buf_remain < 0 || buf_remain > buf_size)
		return -EINVAL;

	if (read_size > buf_remain)
		read_size = buf_remain;

	/* copy_to_user returns number of bytes NOT read */
	num_read = read_size - copy_to_user(dest, read_pos, read_size);
	if (num_read == 0)
		return -EFAULT;
	*ppos += num_read;

	return (num_read);
}

MALLOC_DECLARE(M_LSATTR);

#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)		\
static inline int							\
__fops ## _open(struct inode *inode, struct file *filp)			\
{									\
	return (simple_attr_open(inode, filp, __get, __set, __fmt));	\
}									\
static const struct file_operations __fops = {				\
	.owner	 = THIS_MODULE,						\
	.open	 = __fops ## _open,					\
	.release = simple_attr_release,					\
	.read	 = simple_attr_read,					\
	.write	 = simple_attr_write,					\
	.llseek	 = no_llseek						\
}

int simple_attr_open(struct inode *inode, struct file *filp,
    int (*get)(void *, uint64_t *), int (*set)(void *, uint64_t),
    const char *fmt);

int simple_attr_release(struct inode *inode, struct file *filp);

ssize_t simple_attr_read(struct file *filp, char *buf, size_t read_size, loff_t *ppos);

ssize_t simple_attr_write(struct file *filp, const char *buf, size_t write_size, loff_t *ppos);

#endif /* _LINUXKPI_LINUX_FS_H_ */