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1// SPDX-License-Identifier: GPL-2.02/*3 * dir.c4 *5 * Copyright (c) 1999 Al Smith6 */7 8#include <linux/buffer_head.h>9#include "efs.h"10 11static int efs_readdir(struct file *, struct dir_context *);12 13const struct file_operations efs_dir_operations = {14 .llseek = generic_file_llseek,15 .read = generic_read_dir,16 .iterate_shared = efs_readdir,17};18 19const struct inode_operations efs_dir_inode_operations = {20 .lookup = efs_lookup,21};22 23static int efs_readdir(struct file *file, struct dir_context *ctx)24{25 struct inode *inode = file_inode(file);26 efs_block_t block;27 int slot;28 29 if (inode->i_size & (EFS_DIRBSIZE-1))30 pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",31 __func__);32 33 /* work out where this entry can be found */34 block = ctx->pos >> EFS_DIRBSIZE_BITS;35 36 /* each block contains at most 256 slots */37 slot = ctx->pos & 0xff;38 39 /* look at all blocks */40 while (block < inode->i_blocks) {41 struct efs_dir *dirblock;42 struct buffer_head *bh;43 44 /* read the dir block */45 bh = sb_bread(inode->i_sb, efs_bmap(inode, block));46 47 if (!bh) {48 pr_err("%s(): failed to read dir block %d\n",49 __func__, block);50 break;51 }52 53 dirblock = (struct efs_dir *) bh->b_data; 54 55 if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {56 pr_err("%s(): invalid directory block\n", __func__);57 brelse(bh);58 break;59 }60 61 for (; slot < dirblock->slots; slot++) {62 struct efs_dentry *dirslot;63 efs_ino_t inodenum;64 const char *nameptr;65 int namelen;66 67 if (dirblock->space[slot] == 0)68 continue;69 70 dirslot = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));71 72 inodenum = be32_to_cpu(dirslot->inode);73 namelen = dirslot->namelen;74 nameptr = dirslot->name;75 pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n",76 __func__, block, slot, dirblock->slots-1,77 inodenum, nameptr, namelen);78 if (!namelen)79 continue;80 /* found the next entry */81 ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;82 83 /* sanity check */84 if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {85 pr_warn("directory entry %d exceeds directory block\n",86 slot);87 continue;88 }89 90 /* copy filename and data in dirslot */91 if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {92 brelse(bh);93 return 0;94 }95 }96 brelse(bh);97 98 slot = 0;99 block++;100 }101 ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;102 return 0;103}104