// SPDX-License-Identifier: GPL-2.0
/*
 * dir.c
 *
 * Copyright (c) 1999 Al Smith
 */

#include <linux/buffer_head.h>
#include <linux/filelock.h>
#include "efs.h"

static int efs_readdir(struct file *, struct dir_context *);

const struct file_operations efs_dir_operations = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .iterate_shared = efs_readdir,
        .setlease       = generic_setlease,
};

const struct inode_operations efs_dir_inode_operations = {
        .lookup         = efs_lookup,
};

static int efs_readdir(struct file *file, struct dir_context *ctx)
{
        struct inode *inode = file_inode(file);
        efs_block_t             block;
        int                     slot;

        if (inode->i_size & (EFS_DIRBSIZE-1))
                pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
                        __func__);

        /* work out where this entry can be found */
        block = ctx->pos >> EFS_DIRBSIZE_BITS;

        /* each block contains at most 256 slots */
        slot  = ctx->pos & 0xff;

        /* look at all blocks */
        while (block < inode->i_blocks) {
                struct efs_dir          *dirblock;
                struct buffer_head *bh;

                /* read the dir 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);
                        break;
                }

                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);
                        break;
                }

                for (; slot < dirblock->slots; slot++) {
                        struct efs_dentry *dirslot;
                        efs_ino_t inodenum;
                        const char *nameptr;
                        int namelen;

                        if (dirblock->space[slot] == 0)
                                continue;

                        dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));

                        inodenum = be32_to_cpu(dirslot->inode);
                        namelen  = dirslot->namelen;
                        nameptr  = dirslot->name;
                        pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n",
                                 __func__, block, slot, dirblock->slots-1,
                                 inodenum, nameptr, namelen);
                        if (!namelen)
                                continue;
                        /* found the next entry */
                        ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;

                        /* sanity check */
                        if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
                                pr_warn("directory entry %d exceeds directory block\n",
                                        slot);
                                continue;
                        }

                        /* copy filename and data in dirslot */
                        if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
                                brelse(bh);
                                return 0;
                        }
                }
                brelse(bh);

                slot = 0;
                block++;
        }
        ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
        return 0;
}