// SPDX-License-Identifier: GPL-2.0

  /*
   *  file.c
   *
   *  Copyright (C) 1995, 1996 by Volker Lendecke
   *  Modified 1997 Peter Waltenberg, Bill Hawes, David Woodhouse for 2.1 dcache
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/uaccess.h>

  
  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/fcntl.h>
  #include <linux/stat.h>
  #include <linux/mm.h>

  #include <linux/vmalloc.h>

  #include <linux/sched.h>

  #include "ncp_fs.h"

  static int ncp_fsync(struct file *file, loff_t start, loff_t end, int datasync)

  {

  	return file_write_and_wait_range(file, start, end);

  }
  
  /*
   * Open a file with the specified read/write mode.
   */
  int ncp_make_open(struct inode *inode, int right)
  {
  	int error;
  	int access;
  
  	error = -EINVAL;
  	if (!inode) {

  		pr_err("%s: got NULL inode
  ", __func__);

  		goto out;
  	}

  	ncp_dbg(1, "opened=%d, volume # %u, dir entry # %u
  ",

  		atomic_read(&NCP_FINFO(inode)->opened), 
  		NCP_FINFO(inode)->volNumber, 
  		NCP_FINFO(inode)->dirEntNum);
  	error = -EACCES;

  	mutex_lock(&NCP_FINFO(inode)->open_mutex);

  	if (!atomic_read(&NCP_FINFO(inode)->opened)) {
  		struct ncp_entry_info finfo;
  		int result;
  
  		/* tries max. rights */
  		finfo.access = O_RDWR;
  		result = ncp_open_create_file_or_subdir(NCP_SERVER(inode),
  					inode, NULL, OC_MODE_OPEN,
  					0, AR_READ | AR_WRITE, &finfo);
  		if (!result)
  			goto update;
  		/* RDWR did not succeeded, try readonly or writeonly as requested */
  		switch (right) {
  			case O_RDONLY:
  				finfo.access = O_RDONLY;
  				result = ncp_open_create_file_or_subdir(NCP_SERVER(inode),
  					inode, NULL, OC_MODE_OPEN,
  					0, AR_READ, &finfo);
  				break;
  			case O_WRONLY:
  				finfo.access = O_WRONLY;
  				result = ncp_open_create_file_or_subdir(NCP_SERVER(inode),
  					inode, NULL, OC_MODE_OPEN,
  					0, AR_WRITE, &finfo);
  				break;
  		}
  		if (result) {

  			ncp_vdbg("failed, result=%d
  ", result);

  			goto out_unlock;
  		}
  		/*
  		 * Update the inode information.
  		 */
  	update:
  		ncp_update_inode(inode, &finfo);
  		atomic_set(&NCP_FINFO(inode)->opened, 1);
  	}
  
  	access = NCP_FINFO(inode)->access;

  	ncp_vdbg("file open, access=%x
  ", access);

  	if (access == right || access == O_RDWR) {
  		atomic_inc(&NCP_FINFO(inode)->opened);
  		error = 0;
  	}
  
  out_unlock:

  	mutex_unlock(&NCP_FINFO(inode)->open_mutex);

  out:
  	return error;
  }
  
  static ssize_t

  ncp_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

  {

  	struct file *file = iocb->ki_filp;

  	struct inode *inode = file_inode(file);

  	size_t already_read = 0;

  	off_t pos = iocb->ki_pos;

  	size_t bufsize;
  	int error;

  	void *freepage;

  	size_t freelen;

  	ncp_dbg(1, "enter %pD2
  ", file);

  	if (!iov_iter_count(to))

  		return 0;
  	if (pos > inode->i_sb->s_maxbytes)
  		return 0;

  	iov_iter_truncate(to, inode->i_sb->s_maxbytes - pos);

  
  	error = ncp_make_open(inode, O_RDONLY);
  	if (error) {

  		ncp_dbg(1, "open failed, error=%d
  ", error);

  		return error;
  	}
  
  	bufsize = NCP_SERVER(inode)->buffer_size;
  
  	error = -EIO;
  	freelen = ncp_read_bounce_size(bufsize);
  	freepage = vmalloc(freelen);
  	if (!freepage)
  		goto outrel;
  	error = 0;
  	/* First read in as much as possible for each bufsize. */

  	while (iov_iter_count(to)) {

  		int read_this_time;

  		size_t to_read = min_t(size_t,

  				     bufsize - (pos % bufsize),

  				     iov_iter_count(to));

  
  		error = ncp_read_bounce(NCP_SERVER(inode),
  			 	NCP_FINFO(inode)->file_handle,

  				pos, to_read, to, &read_this_time, 

  				freepage, freelen);
  		if (error) {
  			error = -EIO;	/* NW errno -> Linux errno */
  			break;
  		}
  		pos += read_this_time;

  		already_read += read_this_time;

  		if (read_this_time != to_read)

  			break;

  	}
  	vfree(freepage);

  	iocb->ki_pos = pos;

  
  	file_accessed(file);

  	ncp_dbg(1, "exit %pD2
  ", file);

  outrel:
  	ncp_inode_close(inode);		
  	return already_read ? already_read : error;
  }
  
  static ssize_t

  ncp_file_write_iter(struct kiocb *iocb, struct iov_iter *from)

  {

  	struct file *file = iocb->ki_filp;

  	struct inode *inode = file_inode(file);

  	size_t already_written = 0;

  	size_t bufsize;
  	int errno;

  	void *bouncebuffer;

  	off_t pos;

  	ncp_dbg(1, "enter %pD2
  ", file);

  	errno = generic_write_checks(iocb, from);
  	if (errno <= 0)

  		return errno;

  	errno = ncp_make_open(inode, O_WRONLY);
  	if (errno) {

  		ncp_dbg(1, "open failed, error=%d
  ", errno);

  		return errno;
  	}
  	bufsize = NCP_SERVER(inode)->buffer_size;

  	errno = file_update_time(file);
  	if (errno)
  		goto outrel;

  	bouncebuffer = vmalloc(bufsize);
  	if (!bouncebuffer) {
  		errno = -EIO;	/* -ENOMEM */
  		goto outrel;
  	}

  	pos = iocb->ki_pos;

  	while (iov_iter_count(from)) {

  		int written_this_time;

  		size_t to_write = min_t(size_t,

  				      bufsize - (pos % bufsize),

  				      iov_iter_count(from));

  		if (!copy_from_iter_full(bouncebuffer, to_write, from)) {

  			errno = -EFAULT;
  			break;
  		}
  		if (ncp_write_kernel(NCP_SERVER(inode), 
  		    NCP_FINFO(inode)->file_handle,
  		    pos, to_write, bouncebuffer, &written_this_time) != 0) {
  			errno = -EIO;
  			break;
  		}
  		pos += written_this_time;

  		already_written += written_this_time;

  		if (written_this_time != to_write)

  			break;

  	}
  	vfree(bouncebuffer);

  	iocb->ki_pos = pos;

  	if (pos > i_size_read(inode)) {

  		inode_lock(inode);

  		if (pos > i_size_read(inode))
  			i_size_write(inode, pos);

  		inode_unlock(inode);

  	}

  	ncp_dbg(1, "exit %pD2
  ", file);

  outrel:
  	ncp_inode_close(inode);		
  	return already_written ? already_written : errno;
  }
  
  static int ncp_release(struct inode *inode, struct file *file) {
  	if (ncp_make_closed(inode)) {

  		ncp_dbg(1, "failed to close
  ");

  	}
  	return 0;
  }

  const struct file_operations ncp_file_operations =

  {

  	.llseek		= generic_file_llseek,

  	.read_iter	= ncp_file_read_iter,
  	.write_iter	= ncp_file_write_iter,

  	.unlocked_ioctl	= ncp_ioctl,

  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= ncp_compat_ioctl,
  #endif

  	.mmap		= ncp_mmap,
  	.release	= ncp_release,
  	.fsync		= ncp_fsync,
  };

  const struct inode_operations ncp_file_inode_operations =

  {
  	.setattr	= ncp_notify_change,
  };