1/*
2 * dir.c
3 *
4 * Copyright (c) 1999 Al Smith
5 */
6
7#include <linux/buffer_head.h>
8#include "efs.h"
9
10static int efs_readdir(struct file *, struct dir_context *);
11
12const struct file_operations efs_dir_operations = {
13	.llseek		= generic_file_llseek,
14	.read		= generic_read_dir,
15	.iterate	= efs_readdir,
16};
17
18const struct inode_operations efs_dir_inode_operations = {
19	.lookup		= efs_lookup,
20};
21
22static int efs_readdir(struct file *file, struct dir_context *ctx)
23{
24	struct inode *inode = file_inode(file);
25	efs_block_t		block;
26	int			slot;
27
28	if (inode->i_size & (EFS_DIRBSIZE-1))
29		pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
30			__func__);
31
32	/* work out where this entry can be found */
33	block = ctx->pos >> EFS_DIRBSIZE_BITS;
34
35	/* each block contains at most 256 slots */
36	slot  = ctx->pos & 0xff;
37
38	/* look at all blocks */
39	while (block < inode->i_blocks) {
40		struct efs_dir		*dirblock;
41		struct buffer_head *bh;
42
43		/* read the dir block */
44		bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
45
46		if (!bh) {
47			pr_err("%s(): failed to read dir block %d\n",
48			       __func__, block);
49			break;
50		}
51
52		dirblock = (struct efs_dir *) bh->b_data;
53
54		if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
55			pr_err("%s(): invalid directory block\n", __func__);
56			brelse(bh);
57			break;
58		}
59
60		for (; slot < dirblock->slots; slot++) {
61			struct efs_dentry *dirslot;
62			efs_ino_t inodenum;
63			const char *nameptr;
64			int namelen;
65
66			if (dirblock->space[slot] == 0)
67				continue;
68
69			dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
70
71			inodenum = be32_to_cpu(dirslot->inode);
72			namelen  = dirslot->namelen;
73			nameptr  = dirslot->name;
74			pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n",
75				 __func__, block, slot, dirblock->slots-1,
76				 inodenum, nameptr, namelen);
77			if (!namelen)
78				continue;
79			/* found the next entry */
80			ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
81
82			/* sanity check */
83			if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
84				pr_warn("directory entry %d exceeds directory block\n",
85					slot);
86				continue;
87			}
88
89			/* copy filename and data in dirslot */
90			if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
91				brelse(bh);
92				return 0;
93			}
94		}
95		brelse(bh);
96
97		slot = 0;
98		block++;
99	}
100	ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
101	return 0;
102}
103
104