1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2017-2018 HUAWEI, Inc. |
4 | * https://www.huawei.com/ |
5 | * Copyright (C) 2022, Alibaba Cloud |
6 | */ |
7 | #include "internal.h" |
8 | |
9 | static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx, |
10 | void *dentry_blk, struct erofs_dirent *de, |
11 | unsigned int nameoff, unsigned int maxsize) |
12 | { |
13 | const struct erofs_dirent *end = dentry_blk + nameoff; |
14 | |
15 | while (de < end) { |
16 | const char *de_name; |
17 | unsigned int de_namelen; |
18 | unsigned char d_type; |
19 | |
20 | d_type = fs_ftype_to_dtype(filetype: de->file_type); |
21 | |
22 | nameoff = le16_to_cpu(de->nameoff); |
23 | de_name = (char *)dentry_blk + nameoff; |
24 | |
25 | /* the last dirent in the block? */ |
26 | if (de + 1 >= end) |
27 | de_namelen = strnlen(p: de_name, maxlen: maxsize - nameoff); |
28 | else |
29 | de_namelen = le16_to_cpu(de[1].nameoff) - nameoff; |
30 | |
31 | /* a corrupted entry is found */ |
32 | if (nameoff + de_namelen > maxsize || |
33 | de_namelen > EROFS_NAME_LEN) { |
34 | erofs_err(dir->i_sb, "bogus dirent @ nid %llu" , |
35 | EROFS_I(dir)->nid); |
36 | DBG_BUGON(1); |
37 | return -EFSCORRUPTED; |
38 | } |
39 | |
40 | if (!dir_emit(ctx, name: de_name, namelen: de_namelen, |
41 | le64_to_cpu(de->nid), type: d_type)) |
42 | return 1; |
43 | ++de; |
44 | ctx->pos += sizeof(struct erofs_dirent); |
45 | } |
46 | return 0; |
47 | } |
48 | |
49 | static int erofs_readdir(struct file *f, struct dir_context *ctx) |
50 | { |
51 | struct inode *dir = file_inode(f); |
52 | struct erofs_buf buf = __EROFS_BUF_INITIALIZER; |
53 | struct super_block *sb = dir->i_sb; |
54 | unsigned long bsz = sb->s_blocksize; |
55 | const size_t dirsize = i_size_read(inode: dir); |
56 | unsigned int i = erofs_blknr(sb, ctx->pos); |
57 | unsigned int ofs = erofs_blkoff(sb, ctx->pos); |
58 | int err = 0; |
59 | bool initial = true; |
60 | |
61 | buf.inode = dir; |
62 | while (ctx->pos < dirsize) { |
63 | struct erofs_dirent *de; |
64 | unsigned int nameoff, maxsize; |
65 | |
66 | de = erofs_bread(buf: &buf, blkaddr: i, type: EROFS_KMAP); |
67 | if (IS_ERR(ptr: de)) { |
68 | erofs_err(sb, "fail to readdir of logical block %u of nid %llu" , |
69 | i, EROFS_I(dir)->nid); |
70 | err = PTR_ERR(ptr: de); |
71 | break; |
72 | } |
73 | |
74 | nameoff = le16_to_cpu(de->nameoff); |
75 | if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) { |
76 | erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu" , |
77 | nameoff, EROFS_I(dir)->nid); |
78 | err = -EFSCORRUPTED; |
79 | break; |
80 | } |
81 | |
82 | maxsize = min_t(unsigned int, dirsize - ctx->pos + ofs, bsz); |
83 | |
84 | /* search dirents at the arbitrary position */ |
85 | if (initial) { |
86 | initial = false; |
87 | |
88 | ofs = roundup(ofs, sizeof(struct erofs_dirent)); |
89 | ctx->pos = erofs_pos(sb, i) + ofs; |
90 | if (ofs >= nameoff) |
91 | goto skip_this; |
92 | } |
93 | |
94 | err = erofs_fill_dentries(dir, ctx, dentry_blk: de, de: (void *)de + ofs, |
95 | nameoff, maxsize); |
96 | if (err) |
97 | break; |
98 | skip_this: |
99 | ctx->pos = erofs_pos(sb, i) + maxsize; |
100 | ++i; |
101 | ofs = 0; |
102 | } |
103 | erofs_put_metabuf(buf: &buf); |
104 | return err < 0 ? err : 0; |
105 | } |
106 | |
107 | const struct file_operations erofs_dir_fops = { |
108 | .llseek = generic_file_llseek, |
109 | .read = generic_read_dir, |
110 | .iterate_shared = erofs_readdir, |
111 | }; |
112 | |