cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dir.c (2435B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * dir.c
      4 *
      5 * Copyright (c) 1999 Al Smith
      6 */
      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}