// SPDX-License-Identifier: GPL-2.0 /* * dir.c * * Copyright (c) 1999 Al Smith */ #include <linux/buffer_head.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, }; 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; }