/*
   * Copyright IBM Corporation, 2010
   * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of version 2.1 of the GNU Lesser General Public License
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it would be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   *
   */
  
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  #include <linux/slab.h>

  #include <linux/sched.h>

  #include <linux/posix_acl_xattr.h>
  #include "xattr.h"
  #include "acl.h"

  #include "v9fs.h"

  #include "v9fs_vfs.h"

  #include "fid.h"

  
  static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
  {
  	ssize_t size;
  	void *value = NULL;

  	struct posix_acl *acl = NULL;

  
  	size = v9fs_fid_xattr_get(fid, name, NULL, 0);
  	if (size > 0) {
  		value = kzalloc(size, GFP_NOFS);
  		if (!value)
  			return ERR_PTR(-ENOMEM);
  		size = v9fs_fid_xattr_get(fid, name, value, size);
  		if (size > 0) {

  			acl = posix_acl_from_xattr(&init_user_ns, value, size);

  			if (IS_ERR(acl))
  				goto err_out;
  		}
  	} else if (size == -ENODATA || size == 0 ||
  		   size == -ENOSYS || size == -EOPNOTSUPP) {
  		acl = NULL;
  	} else
  		acl = ERR_PTR(-EIO);
  
  err_out:
  	kfree(value);
  	return acl;
  }
  
  int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
  {
  	int retval = 0;
  	struct posix_acl *pacl, *dacl;

  	struct v9fs_session_info *v9ses;

  	v9ses = v9fs_inode2v9ses(inode);

  	if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
  			((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {

  		set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
  		set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
  		return 0;
  	}

  	/* get the default/access acl values and cache them */

  	dacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_DEFAULT);
  	pacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_ACCESS);

  
  	if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
  		set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
  		set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);

  	} else
  		retval = -EIO;

  	if (!IS_ERR(dacl))
  		posix_acl_release(dacl);
  
  	if (!IS_ERR(pacl))
  		posix_acl_release(pacl);

  	return retval;
  }
  
  static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
  {
  	struct posix_acl *acl;
  	/*
  	 * 9p Always cache the acl value when
  	 * instantiating the inode (v9fs_inode_from_fid)
  	 */
  	acl = get_cached_acl(inode, type);

  	BUG_ON(is_uncached_acl(acl));

  	return acl;
  }

  struct posix_acl *v9fs_iop_get_acl(struct inode *inode, int type)

  {

  	struct v9fs_session_info *v9ses;
  
  	v9ses = v9fs_inode2v9ses(inode);

  	if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
  			((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {

  		/*

  		 * On access = client  and acl = on mode get the acl

  		 * values from the server
  		 */

  		return NULL;

  	}

  	return v9fs_get_cached_acl(inode, type);

  }

  static int v9fs_set_acl(struct p9_fid *fid, int type, struct posix_acl *acl)

  {
  	int retval;
  	char *name;
  	size_t size;
  	void *buffer;

  	if (!acl)
  		return 0;

  	/* Set a setxattr request to server */
  	size = posix_acl_xattr_size(acl->a_count);
  	buffer = kmalloc(size, GFP_KERNEL);
  	if (!buffer)
  		return -ENOMEM;

  	retval = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);

  	if (retval < 0)
  		goto err_free_out;
  	switch (type) {
  	case ACL_TYPE_ACCESS:

  		name = XATTR_NAME_POSIX_ACL_ACCESS;

  		break;
  	case ACL_TYPE_DEFAULT:

  		name = XATTR_NAME_POSIX_ACL_DEFAULT;

  		break;
  	default:
  		BUG();
  	}

  	retval = v9fs_fid_xattr_set(fid, name, buffer, size, 0);

  err_free_out:
  	kfree(buffer);
  	return retval;
  }

  int v9fs_acl_chmod(struct inode *inode, struct p9_fid *fid)

  {
  	int retval = 0;

  	struct posix_acl *acl;

  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  	acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
  	if (acl) {

  		retval = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);

  		if (retval)
  			return retval;

  		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);

  		retval = v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);

  		posix_acl_release(acl);

  	}
  	return retval;
  }

  int v9fs_set_create_acl(struct inode *inode, struct p9_fid *fid,

  			struct posix_acl *dacl, struct posix_acl *acl)

  {

  	set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
  	set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
  	v9fs_set_acl(fid, ACL_TYPE_DEFAULT, dacl);
  	v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);

  	return 0;
  }

  void v9fs_put_acl(struct posix_acl *dacl,
  		  struct posix_acl *acl)
  {
  	posix_acl_release(dacl);
  	posix_acl_release(acl);
  }

  int v9fs_acl_mode(struct inode *dir, umode_t *modep,

  		  struct posix_acl **dpacl, struct posix_acl **pacl)
  {
  	int retval = 0;

  	umode_t mode = *modep;

  	struct posix_acl *acl = NULL;
  
  	if (!S_ISLNK(mode)) {
  		acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
  		if (IS_ERR(acl))
  			return PTR_ERR(acl);
  		if (!acl)
  			mode &= ~current_umask();
  	}
  	if (acl) {

  		if (S_ISDIR(mode))

  			*dpacl = posix_acl_dup(acl);

  		retval = __posix_acl_create(&acl, GFP_NOFS, &mode);

  		if (retval < 0)
  			return retval;

  		if (retval > 0)

  			*pacl = acl;

  		else

  			posix_acl_release(acl);

  	}
  	*modep  = mode;
  	return 0;

  }

  static int v9fs_xattr_get_acl(const struct xattr_handler *handler,

  			      struct dentry *dentry, struct inode *inode,
  			      const char *name, void *buffer, size_t size)

  {

  	struct v9fs_session_info *v9ses;

  	struct posix_acl *acl;
  	int error;

  	v9ses = v9fs_dentry2v9ses(dentry);

  	/*
  	 * We allow set/get/list of acl when access=client is not specified
  	 */
  	if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)

  		return v9fs_xattr_get(dentry, handler->name, buffer, size);

  	acl = v9fs_get_cached_acl(inode, handler->flags);

  	if (IS_ERR(acl))
  		return PTR_ERR(acl);
  	if (acl == NULL)
  		return -ENODATA;

  	error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);

  	posix_acl_release(acl);
  
  	return error;
  }

  static int v9fs_xattr_set_acl(const struct xattr_handler *handler,

  			      struct dentry *dentry, struct inode *inode,
  			      const char *name, const void *value,
  			      size_t size, int flags)

  {

  	int retval;
  	struct posix_acl *acl;

  	struct v9fs_session_info *v9ses;

  	v9ses = v9fs_dentry2v9ses(dentry);

  	/*
  	 * set the attribute on the remote. Without even looking at the
  	 * xattr value. We leave it to the server to validate
  	 */
  	if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)

  		return v9fs_xattr_set(dentry, handler->name, value, size,

  				      flags);

  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;

  	if (!inode_owner_or_capable(inode))

  		return -EPERM;
  	if (value) {
  		/* update the cached acl value */

  		acl = posix_acl_from_xattr(&init_user_ns, value, size);

  		if (IS_ERR(acl))
  			return PTR_ERR(acl);
  		else if (acl) {

  			retval = posix_acl_valid(inode->i_sb->s_user_ns, acl);

  			if (retval)
  				goto err_out;
  		}
  	} else
  		acl = NULL;

  	switch (handler->flags) {

  	case ACL_TYPE_ACCESS:

  		if (acl) {

  			struct iattr iattr;
  
  			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
  			if (retval)

  				goto err_out;

  			if (!acl) {
  				/*
  				 * ACL can be represented
  				 * by the mode bits. So don't
  				 * update ACL.

  				 */

  				value = NULL;
  				size = 0;

  			}

  			iattr.ia_valid = ATTR_MODE;
  			/* FIXME should we update ctime ?
  			 * What is the following setxattr update the
  			 * mode ?
  			 */
  			v9fs_vfs_setattr_dotl(dentry, &iattr);

  		}
  		break;
  	case ACL_TYPE_DEFAULT:

  		if (!S_ISDIR(inode->i_mode)) {

  			retval = acl ? -EINVAL : 0;

  			goto err_out;
  		}
  		break;
  	default:
  		BUG();
  	}

  	retval = v9fs_xattr_set(dentry, handler->name, value, size, flags);

  	if (!retval)

  		set_cached_acl(inode, handler->flags, acl);

  err_out:
  	posix_acl_release(acl);
  	return retval;

  }
  
  const struct xattr_handler v9fs_xattr_acl_access_handler = {

  	.name	= XATTR_NAME_POSIX_ACL_ACCESS,

  	.flags	= ACL_TYPE_ACCESS,
  	.get	= v9fs_xattr_get_acl,
  	.set	= v9fs_xattr_set_acl,
  };
  
  const struct xattr_handler v9fs_xattr_acl_default_handler = {

  	.name	= XATTR_NAME_POSIX_ACL_DEFAULT,

  	.flags	= ACL_TYPE_DEFAULT,
  	.get	= v9fs_xattr_get_acl,
  	.set	= v9fs_xattr_set_acl,
  };