/*
 * Copyright (C) 2007 Red Hat.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/posix_acl.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include "ctree.h"
#include "btrfs_inode.h"
#include "xattr.h"

struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
{
        int size;
        const char *name;
        char *value = NULL;
        struct posix_acl *acl;

        if (!IS_POSIXACL(inode))
                return NULL;

        acl = get_cached_acl(inode, type);
        if (acl != ACL_NOT_CACHED)
                return acl;

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = POSIX_ACL_XATTR_ACCESS;
                break;
        case ACL_TYPE_DEFAULT:
                name = POSIX_ACL_XATTR_DEFAULT;
                break;
        default:
                BUG();
        }

        size = __btrfs_getxattr(inode, name, "", 0);
        if (size > 0) {
                value = kzalloc(size, GFP_NOFS);
                if (!value)
                        return ERR_PTR(-ENOMEM);
                size = __btrfs_getxattr(inode, name, value, size);
        }
        if (size > 0) {
                acl = posix_acl_from_xattr(&init_user_ns, value, size);
        } else if (size == -ENOENT || size == -ENODATA || size == 0) {
                /* FIXME, who returns -ENOENT?  I think nobody */
                acl = NULL;
        } else {
                acl = ERR_PTR(-EIO);
        }
        kfree(value);

        if (!IS_ERR(acl))
                set_cached_acl(inode, type, acl);

        return acl;
}

static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
                void *value, size_t size, int type)
{
        struct posix_acl *acl;
        int ret = 0;

        if (!IS_POSIXACL(dentry->d_inode))
                return -EOPNOTSUPP;

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

        if (IS_ERR(acl))
                return PTR_ERR(acl);
        if (acl == NULL)
                return -ENODATA;
        ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
        posix_acl_release(acl);

        return ret;
}

/*
 * Needs to be called with fs_mutex held
 */
static int btrfs_set_acl(struct btrfs_trans_handle *trans,
                         struct inode *inode, struct posix_acl *acl, int type)
{
        int ret, size = 0;
        const char *name;
        char *value = NULL;

        if (acl) {
                ret = posix_acl_valid(acl);
                if (ret < 0)
                        return ret;
                ret = 0;
        }

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = POSIX_ACL_XATTR_ACCESS;
                if (acl) {
                        ret = posix_acl_equiv_mode(acl, &inode->i_mode);
                        if (ret < 0)
                                return ret;
                        if (ret == 0)
                                acl = NULL;
                }
                ret = 0;
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode))
                        return acl ? -EINVAL : 0;
                name = POSIX_ACL_XATTR_DEFAULT;
                break;
        default:
                return -EINVAL;
        }

        if (acl) {
                size = posix_acl_xattr_size(acl->a_count);
                value = kmalloc(size, GFP_NOFS);
                if (!value) {
                        ret = -ENOMEM;
                        goto out;
                }

                ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
                if (ret < 0)
                        goto out;
        }

        ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
out:
        kfree(value);

        if (!ret)
                set_cached_acl(inode, type, acl);

        return ret;
}

static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
                const void *value, size_t size, int flags, int type)
{
        int ret;
        struct posix_acl *acl = NULL;

        if (!inode_owner_or_capable(dentry->d_inode))
                return -EPERM;

        if (!IS_POSIXACL(dentry->d_inode))
                return -EOPNOTSUPP;

        if (value) {
                acl = posix_acl_from_xattr(&init_user_ns, value, size);
                if (IS_ERR(acl))
                        return PTR_ERR(acl);

                if (acl) {
                        ret = posix_acl_valid(acl);
                        if (ret)
                                goto out;
                }
        }

        ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
out:
        posix_acl_release(acl);

        return ret;
}

/*
 * btrfs_init_acl is already generally called under fs_mutex, so the locking
 * stuff has been fixed to work with that.  If the locking stuff changes, we
 * need to re-evaluate the acl locking stuff.
 */
int btrfs_init_acl(struct btrfs_trans_handle *trans,
                   struct inode *inode, struct inode *dir)
{
        struct posix_acl *acl = NULL;
        int ret = 0;

        /* this happens with subvols */
        if (!dir)
                return 0;

        if (!S_ISLNK(inode->i_mode)) {
                if (IS_POSIXACL(dir)) {
                        acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
                        if (IS_ERR(acl))
                                return PTR_ERR(acl);
                }

                if (!acl)
                        inode->i_mode &= ~current_umask();
        }

        if (IS_POSIXACL(dir) && acl) {
                if (S_ISDIR(inode->i_mode)) {
                        ret = btrfs_set_acl(trans, inode, acl,
                                            ACL_TYPE_DEFAULT);
                        if (ret)
                                goto failed;
                }
                ret = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
                if (ret < 0)
                        return ret;

                if (ret > 0) {
                        /* we need an acl */
                        ret = btrfs_set_acl(trans, inode, acl, ACL_TYPE_ACCESS);
                } else {
                        cache_no_acl(inode);
                }
        } else {
                cache_no_acl(inode);
        }
failed:
        posix_acl_release(acl);

        return ret;
}

int btrfs_acl_chmod(struct inode *inode)
{
        struct posix_acl *acl;
        int ret = 0;

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

        if (!IS_POSIXACL(inode))
                return 0;

        acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
        if (IS_ERR_OR_NULL(acl))
                return PTR_ERR(acl);

        ret = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
        if (ret)
                return ret;
        ret = btrfs_set_acl(NULL, inode, acl, ACL_TYPE_ACCESS);
        posix_acl_release(acl);
        return ret;
}

const struct xattr_handler btrfs_xattr_acl_default_handler = {
        .prefix = POSIX_ACL_XATTR_DEFAULT,
        .flags  = ACL_TYPE_DEFAULT,
        .get    = btrfs_xattr_acl_get,
        .set    = btrfs_xattr_acl_set,
};

const struct xattr_handler btrfs_xattr_acl_access_handler = {
        .prefix = POSIX_ACL_XATTR_ACCESS,
        .flags  = ACL_TYPE_ACCESS,
        .get    = btrfs_xattr_acl_get,
        .set    = btrfs_xattr_acl_set,
};