// SPDX-License-Identifier: GPL-2.0
/*
 * namei.c
 *
 * Copyright (c) 1999 Al Smith
 *
 * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
 */

#include <linux/buffer_head.h>
#include <linux/string.h>
#include <linux/exportfs.h>
#include "efs.h"


static efs_ino_t efs_find_entry(struct inode *inode, const char *name, int len)
{
        struct buffer_head *bh;

        int                     slot, namelen;
        char                    *nameptr;
        struct efs_dir          *dirblock;
        struct efs_dentry       *dirslot;
        efs_ino_t               inodenum;
        efs_block_t             block;
 
        if (inode->i_size & (EFS_DIRBSIZE-1))
                pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
                        __func__);

        for(block = 0; block < inode->i_blocks; block++) {

                bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
                if (!bh) {
                        pr_err("%s(): failed to read dir block %d\n",
                               __func__, block);
                        return 0;
                }
    
                dirblock = (struct efs_dir *) bh->b_data;

                if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
                        pr_err("%s(): invalid directory block\n", __func__);
                        brelse(bh);
                        return 0;
                }

                for (slot = 0; slot < dirblock->slots; slot++) {
                        dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));

                        namelen  = dirslot->namelen;
                        nameptr  = dirslot->name;

                        if ((namelen == len) && (!memcmp(name, nameptr, len))) {
                                inodenum = be32_to_cpu(dirslot->inode);
                                brelse(bh);
                                return inodenum;
                        }
                }
                brelse(bh);
        }
        return 0;
}

struct dentry *efs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
        efs_ino_t inodenum;
        struct inode *inode = NULL;

        inodenum = efs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
        if (inodenum)
                inode = efs_iget(dir->i_sb, inodenum);

        return d_splice_alias(inode, dentry);
}

static struct inode *efs_nfs_get_inode(struct super_block *sb, u64 ino,
                u32 generation)
{
        struct inode *inode;

        if (ino == 0)
                return ERR_PTR(-ESTALE);
        inode = efs_iget(sb, ino);
        if (IS_ERR(inode))
                return ERR_CAST(inode);

        if (generation && inode->i_generation != generation) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }

        return inode;
}

struct dentry *efs_fh_to_dentry(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                                    efs_nfs_get_inode);
}

struct dentry *efs_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                                    efs_nfs_get_inode);
}

struct dentry *efs_get_parent(struct dentry *child)
{
        struct dentry *parent = ERR_PTR(-ENOENT);
        efs_ino_t ino;

        ino = efs_find_entry(d_inode(child), "..", 2);
        if (ino)
                parent = d_obtain_alias(efs_iget(child->d_sb, ino));

        return parent;
}