/*

   * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
   *
   * This file is released under the GPL.

   *
   * Generic ACL support for in-memory filesystems.

   */
  
  #include <linux/sched.h>

  #include <linux/gfp.h>

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

  #include <linux/posix_acl.h>
  #include <linux/posix_acl_xattr.h>

  
  static size_t
  generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
  		const char *name, size_t name_len, int type)

  {
  	struct posix_acl *acl;

  	const char *xname;

  	size_t size;

  	acl = get_cached_acl(dentry->d_inode, type);

  	if (!acl)
  		return 0;
  	posix_acl_release(acl);

  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		xname = POSIX_ACL_XATTR_ACCESS;
  		break;
  	case ACL_TYPE_DEFAULT:
  		xname = POSIX_ACL_XATTR_DEFAULT;
  		break;
  	default:
  		return 0;

  	}

  	size = strlen(xname) + 1;

  	if (list && size <= list_size)

  		memcpy(list, xname, size);

  	return size;
  }

  static int
  generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
  		     size_t size, int type)

  {
  	struct posix_acl *acl;
  	int error;

  	if (strcmp(name, "") != 0)
  		return -EINVAL;
  
  	acl = get_cached_acl(dentry->d_inode, type);

  	if (!acl)
  		return -ENODATA;
  	error = posix_acl_to_xattr(acl, buffer, size);
  	posix_acl_release(acl);
  
  	return error;
  }

  static int
  generic_acl_set(struct dentry *dentry, const char *name, const void *value,
  		     size_t size, int flags, int type)

  {

  	struct inode *inode = dentry->d_inode;

  	struct posix_acl *acl = NULL;
  	int error;

  	if (strcmp(name, "") != 0)
  		return -EINVAL;

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

  	if (!inode_owner_or_capable(inode))

  		return -EPERM;
  	if (value) {
  		acl = posix_acl_from_xattr(value, size);
  		if (IS_ERR(acl))
  			return PTR_ERR(acl);
  	}
  	if (acl) {

  		error = posix_acl_valid(acl);
  		if (error)
  			goto failed;

  		switch (type) {
  		case ACL_TYPE_ACCESS:

  			error = posix_acl_equiv_mode(acl, &inode->i_mode);

  			if (error < 0)
  				goto failed;

  			inode->i_ctime = CURRENT_TIME;

  			if (error == 0) {
  				posix_acl_release(acl);
  				acl = NULL;
  			}
  			break;
  		case ACL_TYPE_DEFAULT:
  			if (!S_ISDIR(inode->i_mode)) {
  				error = -EINVAL;
  				goto failed;
  			}
  			break;

  		}
  	}

  	set_cached_acl(inode, type, acl);

  	error = 0;
  failed:
  	posix_acl_release(acl);
  	return error;
  }
  
  /**
   * generic_acl_init  -  Take care of acl inheritance at @inode create time

   *
   * Files created inside a directory with a default ACL inherit the
   * directory's default ACL.
   */
  int

  generic_acl_init(struct inode *inode, struct inode *dir)

  {
  	struct posix_acl *acl = NULL;

  	int error;

  	if (!S_ISLNK(inode->i_mode))

  		acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);

  	if (acl) {

  		if (S_ISDIR(inode->i_mode))
  			set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);

  		error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);

  		if (error < 0)
  			return error;

  		if (error > 0)
  			set_cached_acl(inode, ACL_TYPE_ACCESS, acl);

  	} else {
  		inode->i_mode &= ~current_umask();

  	}
  	error = 0;

  	posix_acl_release(acl);
  	return error;
  }
  
  /**
   * generic_acl_chmod  -  change the access acl of @inode upon chmod()

   *
   * A chmod also changes the permissions of the owner, group/mask, and
   * other ACL entries.
   */
  int

  generic_acl_chmod(struct inode *inode)

  {

  	struct posix_acl *acl;

  	int error = 0;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;

  	acl = get_cached_acl(inode, ACL_TYPE_ACCESS);

  	if (acl) {

  		error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
  		if (error)
  			return error;
  		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);

  		posix_acl_release(acl);

  	}
  	return error;
  }

  const struct xattr_handler generic_acl_access_handler = {

  	.prefix = POSIX_ACL_XATTR_ACCESS,
  	.flags	= ACL_TYPE_ACCESS,
  	.list	= generic_acl_list,
  	.get	= generic_acl_get,
  	.set	= generic_acl_set,
  };

  const struct xattr_handler generic_acl_default_handler = {

  	.prefix = POSIX_ACL_XATTR_DEFAULT,
  	.flags	= ACL_TYPE_DEFAULT,
  	.list	= generic_acl_list,
  	.get	= generic_acl_get,
  	.set	= generic_acl_set,
  };