GNU Linux-libre 4.9.308-gnu1
[releases.git] / fs / efs / dir.c
1 /*
2  * dir.c
3  *
4  * Copyright (c) 1999 Al Smith
5  */
6
7 #include <linux/buffer_head.h>
8 #include "efs.h"
9
10 static int efs_readdir(struct file *, struct dir_context *);
11
12 const struct file_operations efs_dir_operations = {
13         .llseek         = generic_file_llseek,
14         .read           = generic_read_dir,
15         .iterate_shared = efs_readdir,
16 };
17
18 const struct inode_operations efs_dir_inode_operations = {
19         .lookup         = efs_lookup,
20 };
21
22 static 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 }