/*
 * linux/fs/ext2/xattr_user.c
 * Handler for extended user attributes.
 *
 * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include "ext2.h"
#include "xattr.h"

#ifdef CONFIG_EXT2_FS_POSIX_ACL
# include "acl.h"
#endif

#define XATTR_USER_PREFIX "user."

static size_t
ext2_xattr_user_list(char *list, struct inode *inode,
		     const char *name, int name_len)
{
	const int prefix_len = sizeof(XATTR_USER_PREFIX)-1;

	if (!test_opt(inode->i_sb, XATTR_USER))
		return 0;

	if (list) {
		memcpy(list, XATTR_USER_PREFIX, prefix_len);
		memcpy(list+prefix_len, name, name_len);
		list[prefix_len + name_len] = '\0';
	}
	return prefix_len + name_len + 1;
}

static int
ext2_xattr_user_get(struct inode *inode, const char *name,
		    void *buffer, size_t size)
{
	int error;

	if (strcmp(name, "") == 0)
		return -EINVAL;
	if (!test_opt(inode->i_sb, XATTR_USER))
		return -EOPNOTSUPP;
#ifdef CONFIG_EXT2_FS_POSIX_ACL
	error = ext2_permission_locked(inode, MAY_READ);
#else
	error = permission(inode, MAY_READ);
#endif
	if (error)
		return error;

	return ext2_xattr_get(inode, EXT2_XATTR_INDEX_USER, name, buffer, size);
}

static int
ext2_xattr_user_set(struct inode *inode, const char *name,
		    const void *value, size_t size, int flags)
{
	int error;

	if (strcmp(name, "") == 0)
		return -EINVAL;
	if (!test_opt(inode->i_sb, XATTR_USER))
		return -EOPNOTSUPP;
	if ( !S_ISREG(inode->i_mode) &&
	    (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
		return -EPERM;
#ifdef CONFIG_EXT2_FS_POSIX_ACL
	error = ext2_permission_locked(inode, MAY_WRITE);
#else
	error = permission(inode, MAY_WRITE);
#endif
	if (error)
		return error;

	return ext2_xattr_set(inode, EXT2_XATTR_INDEX_USER, name,
			      value, size, flags);
}

struct ext2_xattr_handler ext2_xattr_user_handler = {
	.prefix	= XATTR_USER_PREFIX,
	.list	= ext2_xattr_user_list,
	.get	= ext2_xattr_user_get,
	.set	= ext2_xattr_user_set,
};

int __init
init_ext2_xattr_user(void)
{
	return ext2_xattr_register(EXT2_XATTR_INDEX_USER,
				   &ext2_xattr_user_handler);
}

void
exit_ext2_xattr_user(void)
{
	ext2_xattr_unregister(EXT2_XATTR_INDEX_USER,
			      &ext2_xattr_user_handler);
}
