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
11 static int efs_readdir(struct file *, struct dir_context *);
12
13 const struct file_operations efs_dir_operations = {
14 .llseek = generic_file_llseek,
15 .read = generic_read_dir,
16 .iterate_shared = efs_readdir,
17 };
18
19 const struct inode_operations efs_dir_inode_operations = {
20 .lookup = efs_lookup,
21 };
22
efs_readdir(struct file * file,struct dir_context * ctx)23 static 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