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 <linux/filelock.h>
10 #include "efs.h"
11
12 static int efs_readdir(struct file *, struct dir_context *);
13
14 const struct file_operations efs_dir_operations = {
15 .llseek = generic_file_llseek,
16 .read = generic_read_dir,
17 .iterate_shared = efs_readdir,
18 .setlease = generic_setlease,
19 };
20
21 const struct inode_operations efs_dir_inode_operations = {
22 .lookup = efs_lookup,
23 };
24
efs_readdir(struct file * file,struct dir_context * ctx)25 static int efs_readdir(struct file *file, struct dir_context *ctx)
26 {
27 struct inode *inode = file_inode(file);
28 efs_block_t block;
29 int slot;
30
31 if (inode->i_size & (EFS_DIRBSIZE-1))
32 pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
33 __func__);
34
35 /* work out where this entry can be found */
36 block = ctx->pos >> EFS_DIRBSIZE_BITS;
37
38 /* each block contains at most 256 slots */
39 slot = ctx->pos & 0xff;
40
41 /* look at all blocks */
42 while (block < inode->i_blocks) {
43 struct efs_dir *dirblock;
44 struct buffer_head *bh;
45
46 /* read the dir block */
47 bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
48
49 if (!bh) {
50 pr_err("%s(): failed to read dir block %d\n",
51 __func__, block);
52 break;
53 }
54
55 dirblock = (struct efs_dir *) bh->b_data;
56
57 if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
58 pr_err("%s(): invalid directory block\n", __func__);
59 brelse(bh);
60 break;
61 }
62
63 for (; slot < dirblock->slots; slot++) {
64 struct efs_dentry *dirslot;
65 efs_ino_t inodenum;
66 const char *nameptr;
67 int namelen;
68
69 if (dirblock->space[slot] == 0)
70 continue;
71
72 dirslot = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
73
74 inodenum = be32_to_cpu(dirslot->inode);
75 namelen = dirslot->namelen;
76 nameptr = dirslot->name;
77 pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n",
78 __func__, block, slot, dirblock->slots-1,
79 inodenum, nameptr, namelen);
80 if (!namelen)
81 continue;
82 /* found the next entry */
83 ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
84
85 /* sanity check */
86 if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
87 pr_warn("directory entry %d exceeds directory block\n",
88 slot);
89 continue;
90 }
91
92 /* copy filename and data in dirslot */
93 if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
94 brelse(bh);
95 return 0;
96 }
97 }
98 brelse(bh);
99
100 slot = 0;
101 block++;
102 }
103 ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
104 return 0;
105 }
106