GNU Linux-libre 5.19-rc6-gnu
[releases.git] / fs / efs / dir.c
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
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 }