// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/ufs/namei.c
 *
 * Migration to usage of "page cache" on May 2006 by
 * Evgeniy Dushistov <dushistov@mail.ru> based on ext2 code base.
 *
 * Copyright (C) 1998
 * Daniel Pirkl <daniel.pirkl@email.cz>
 * Charles University, Faculty of Mathematics and Physics
 *
 *  from
 *
 *  linux/fs/ext2/namei.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/namei.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

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

#include "ufs_fs.h"
#include "ufs.h"
#include "util.h"

static inline int ufs_add_nondir(struct dentry *dentry, struct inode *inode)
{
        int err = ufs_add_link(dentry, inode);
        if (!err) {
                d_instantiate_new(dentry, inode);
                return 0;
        }
        inode_dec_link_count(inode);
        discard_new_inode(inode);
        return err;
}

static struct dentry *ufs_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
{
        struct inode * inode = NULL;
        ino_t ino;
        
        if (dentry->d_name.len > UFS_MAXNAMLEN)
                return ERR_PTR(-ENAMETOOLONG);

        ino = ufs_inode_by_name(dir, &dentry->d_name);
        if (ino)
                inode = ufs_iget(dir->i_sb, ino);
        return d_splice_alias(inode, dentry);
}

/*
 * By the time this is called, we already have created
 * the directory cache entry for the new file, but it
 * is so far negative - it has no inode.
 *
 * If the create succeeds, we fill in the inode information
 * with d_instantiate(). 
 */
static int ufs_create (struct user_namespace * mnt_userns,
                struct inode * dir, struct dentry * dentry, umode_t mode,
                bool excl)
{
        struct inode *inode;

        inode = ufs_new_inode(dir, mode);
        if (IS_ERR(inode))
                return PTR_ERR(inode);

        inode->i_op = &ufs_file_inode_operations;
        inode->i_fop = &ufs_file_operations;
        inode->i_mapping->a_ops = &ufs_aops;
        mark_inode_dirty(inode);
        return ufs_add_nondir(dentry, inode);
}

static int ufs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
                     struct dentry *dentry, umode_t mode, dev_t rdev)
{
        struct inode *inode;
        int err;

        if (!old_valid_dev(rdev))
                return -EINVAL;

        inode = ufs_new_inode(dir, mode);
        err = PTR_ERR(inode);
        if (!IS_ERR(inode)) {
                init_special_inode(inode, mode, rdev);
                ufs_set_inode_dev(inode->i_sb, UFS_I(inode), rdev);
                mark_inode_dirty(inode);
                err = ufs_add_nondir(dentry, inode);
        }
        return err;
}

static int ufs_symlink (struct user_namespace * mnt_userns, struct inode * dir,
        struct dentry * dentry, const char * symname)
{
        struct super_block * sb = dir->i_sb;
        int err;
        unsigned l = strlen(symname)+1;
        struct inode * inode;

        if (l > sb->s_blocksize)
                return -ENAMETOOLONG;

        inode = ufs_new_inode(dir, S_IFLNK | S_IRWXUGO);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                return err;

        if (l > UFS_SB(sb)->s_uspi->s_maxsymlinklen) {
                /* slow symlink */
                inode->i_op = &page_symlink_inode_operations;
                inode_nohighmem(inode);
                inode->i_mapping->a_ops = &ufs_aops;
                err = page_symlink(inode, symname, l);
                if (err)
                        goto out_fail;
        } else {
                /* fast symlink */
                inode->i_op = &simple_symlink_inode_operations;
                inode->i_link = (char *)UFS_I(inode)->i_u1.i_symlink;
                memcpy(inode->i_link, symname, l);
                inode->i_size = l-1;
        }
        mark_inode_dirty(inode);

        return ufs_add_nondir(dentry, inode);

out_fail:
        inode_dec_link_count(inode);
        discard_new_inode(inode);
        return err;
}

static int ufs_link (struct dentry * old_dentry, struct inode * dir,
        struct dentry *dentry)
{
        struct inode *inode = d_inode(old_dentry);
        int error;

        inode->i_ctime = current_time(inode);
        inode_inc_link_count(inode);
        ihold(inode);

        error = ufs_add_link(dentry, inode);
        if (error) {
                inode_dec_link_count(inode);
                iput(inode);
        } else
                d_instantiate(dentry, inode);
        return error;
}

static int ufs_mkdir(struct user_namespace * mnt_userns, struct inode * dir,
        struct dentry * dentry, umode_t mode)
{
        struct inode * inode;
        int err;

        inode_inc_link_count(dir);

        inode = ufs_new_inode(dir, S_IFDIR|mode);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                goto out_dir;

        inode->i_op = &ufs_dir_inode_operations;
        inode->i_fop = &ufs_dir_operations;
        inode->i_mapping->a_ops = &ufs_aops;

        inode_inc_link_count(inode);

        err = ufs_make_empty(inode, dir);
        if (err)
                goto out_fail;

        err = ufs_add_link(dentry, inode);
        if (err)
                goto out_fail;

        d_instantiate_new(dentry, inode);
        return 0;

out_fail:
        inode_dec_link_count(inode);
        inode_dec_link_count(inode);
        discard_new_inode(inode);
out_dir:
        inode_dec_link_count(dir);
        return err;
}

static int ufs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct inode * inode = d_inode(dentry);
        struct ufs_dir_entry *de;
        struct page *page;
        int err = -ENOENT;

        de = ufs_find_entry(dir, &dentry->d_name, &page);
        if (!de)
                goto out;

        err = ufs_delete_entry(dir, de, page);
        if (err)
                goto out;

        inode->i_ctime = dir->i_ctime;
        inode_dec_link_count(inode);
        err = 0;
out:
        return err;
}

static int ufs_rmdir (struct inode * dir, struct dentry *dentry)
{
        struct inode * inode = d_inode(dentry);
        int err= -ENOTEMPTY;

        if (ufs_empty_dir (inode)) {
                err = ufs_unlink(dir, dentry);
                if (!err) {
                        inode->i_size = 0;
                        inode_dec_link_count(inode);
                        inode_dec_link_count(dir);
                }
        }
        return err;
}

static int ufs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
                      struct dentry *old_dentry, struct inode *new_dir,
                      struct dentry *new_dentry, unsigned int flags)
{
        struct inode *old_inode = d_inode(old_dentry);
        struct inode *new_inode = d_inode(new_dentry);
        struct page *dir_page = NULL;
        struct ufs_dir_entry * dir_de = NULL;
        struct page *old_page;
        struct ufs_dir_entry *old_de;
        int err = -ENOENT;

        if (flags & ~RENAME_NOREPLACE)
                return -EINVAL;

        old_de = ufs_find_entry(old_dir, &old_dentry->d_name, &old_page);
        if (!old_de)
                goto out;

        if (S_ISDIR(old_inode->i_mode)) {
                err = -EIO;
                dir_de = ufs_dotdot(old_inode, &dir_page);
                if (!dir_de)
                        goto out_old;
        }

        if (new_inode) {
                struct page *new_page;
                struct ufs_dir_entry *new_de;

                err = -ENOTEMPTY;
                if (dir_de && !ufs_empty_dir(new_inode))
                        goto out_dir;

                err = -ENOENT;
                new_de = ufs_find_entry(new_dir, &new_dentry->d_name, &new_page);
                if (!new_de)
                        goto out_dir;
                ufs_set_link(new_dir, new_de, new_page, old_inode, 1);
                new_inode->i_ctime = current_time(new_inode);
                if (dir_de)
                        drop_nlink(new_inode);
                inode_dec_link_count(new_inode);
        } else {
                err = ufs_add_link(new_dentry, old_inode);
                if (err)
                        goto out_dir;
                if (dir_de)
                        inode_inc_link_count(new_dir);
        }

        /*
         * Like most other Unix systems, set the ctime for inodes on a
         * rename.
         */
        old_inode->i_ctime = current_time(old_inode);

        ufs_delete_entry(old_dir, old_de, old_page);
        mark_inode_dirty(old_inode);

        if (dir_de) {
                if (old_dir != new_dir)
                        ufs_set_link(old_inode, dir_de, dir_page, new_dir, 0);
                else {
                        kunmap(dir_page);
                        put_page(dir_page);
                }
                inode_dec_link_count(old_dir);
        }
        return 0;


out_dir:
        if (dir_de) {
                kunmap(dir_page);
                put_page(dir_page);
        }
out_old:
        kunmap(old_page);
        put_page(old_page);
out:
        return err;
}

const struct inode_operations ufs_dir_inode_operations = {
        .create         = ufs_create,
        .lookup         = ufs_lookup,
        .link           = ufs_link,
        .unlink         = ufs_unlink,
        .symlink        = ufs_symlink,
        .mkdir          = ufs_mkdir,
        .rmdir          = ufs_rmdir,
        .mknod          = ufs_mknod,
        .rename         = ufs_rename,
};