/*
   * FUSE: Filesystem in Userspace
   * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
   *
   * This program can be distributed under the terms of the GNU GPL.
   * See the file COPYING.
   */
  
  #include "fuse_i.h"
  
  #include <linux/posix_acl.h>
  #include <linux/posix_acl_xattr.h>
  
  struct posix_acl *fuse_get_acl(struct inode *inode, int type)
  {
  	struct fuse_conn *fc = get_fuse_conn(inode);
  	int size;
  	const char *name;
  	void *value = NULL;
  	struct posix_acl *acl;

  	if (fuse_is_bad(inode))
  		return ERR_PTR(-EIO);

  	if (!fc->posix_acl || fc->no_getxattr)
  		return NULL;
  
  	if (type == ACL_TYPE_ACCESS)
  		name = XATTR_NAME_POSIX_ACL_ACCESS;
  	else if (type == ACL_TYPE_DEFAULT)
  		name = XATTR_NAME_POSIX_ACL_DEFAULT;
  	else
  		return ERR_PTR(-EOPNOTSUPP);
  
  	value = kmalloc(PAGE_SIZE, GFP_KERNEL);
  	if (!value)
  		return ERR_PTR(-ENOMEM);
  	size = fuse_getxattr(inode, name, value, PAGE_SIZE);
  	if (size > 0)

  		acl = posix_acl_from_xattr(fc->user_ns, value, size);

  	else if ((size == 0) || (size == -ENODATA) ||
  		 (size == -EOPNOTSUPP && fc->no_getxattr))
  		acl = NULL;
  	else if (size == -ERANGE)
  		acl = ERR_PTR(-E2BIG);
  	else
  		acl = ERR_PTR(size);
  
  	kfree(value);
  	return acl;
  }
  
  int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  {
  	struct fuse_conn *fc = get_fuse_conn(inode);
  	const char *name;
  	int ret;

  	if (fuse_is_bad(inode))
  		return -EIO;

  	if (!fc->posix_acl || fc->no_setxattr)
  		return -EOPNOTSUPP;
  
  	if (type == ACL_TYPE_ACCESS)
  		name = XATTR_NAME_POSIX_ACL_ACCESS;
  	else if (type == ACL_TYPE_DEFAULT)
  		name = XATTR_NAME_POSIX_ACL_DEFAULT;
  	else
  		return -EINVAL;
  
  	if (acl) {
  		/*
  		 * Fuse userspace is responsible for updating access
  		 * permissions in the inode, if needed. fuse_setxattr
  		 * invalidates the inode attributes, which will force
  		 * them to be refreshed the next time they are used,
  		 * and it also updates i_ctime.
  		 */
  		size_t size = posix_acl_xattr_size(acl->a_count);
  		void *value;
  
  		if (size > PAGE_SIZE)
  			return -E2BIG;
  
  		value = kmalloc(size, GFP_KERNEL);
  		if (!value)
  			return -ENOMEM;

  		ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);

  		if (ret < 0) {
  			kfree(value);
  			return ret;
  		}
  
  		ret = fuse_setxattr(inode, name, value, size, 0);
  		kfree(value);
  	} else {
  		ret = fuse_removexattr(inode, name);
  	}
  	forget_all_cached_acls(inode);
  	fuse_invalidate_attr(inode);
  
  	return ret;
  }