/*
 * 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;
                        struct posix_acl *old_acl = acl;

                        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.
                                 */
                                posix_acl_release(old_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,
};