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
erofs_fill_dentries(struct inode * dir,struct dir_context * ctx,void * dentry_blk,struct erofs_dirent * de,unsigned int nameoff,unsigned int maxsize)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(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(de_name, 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, de_name, de_namelen,
41 le64_to_cpu(de->nid), d_type))
42 return 1;
43 ++de;
44 ctx->pos += sizeof(struct erofs_dirent);
45 }
46 return 0;
47 }
48
erofs_readdir(struct file * f,struct dir_context * ctx)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 const size_t dirsize = i_size_read(dir);
54 unsigned int i = ctx->pos / EROFS_BLKSIZ;
55 unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
56 int err = 0;
57 bool initial = true;
58
59 while (ctx->pos < dirsize) {
60 struct erofs_dirent *de;
61 unsigned int nameoff, maxsize;
62
63 de = erofs_bread(&buf, dir, i, EROFS_KMAP);
64 if (IS_ERR(de)) {
65 erofs_err(dir->i_sb,
66 "fail to readdir of logical block %u of nid %llu",
67 i, EROFS_I(dir)->nid);
68 err = PTR_ERR(de);
69 break;
70 }
71
72 nameoff = le16_to_cpu(de->nameoff);
73 if (nameoff < sizeof(struct erofs_dirent) ||
74 nameoff >= EROFS_BLKSIZ) {
75 erofs_err(dir->i_sb,
76 "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,
83 dirsize - ctx->pos + ofs, EROFS_BLKSIZ);
84
85 /* search dirents at the arbitrary position */
86 if (initial) {
87 initial = false;
88
89 ofs = roundup(ofs, sizeof(struct erofs_dirent));
90 ctx->pos = blknr_to_addr(i) + ofs;
91 if (ofs >= nameoff)
92 goto skip_this;
93 }
94
95 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
96 nameoff, maxsize);
97 if (err)
98 break;
99 skip_this:
100 ctx->pos = blknr_to_addr(i) + maxsize;
101 ++i;
102 ofs = 0;
103 }
104 erofs_put_metabuf(&buf);
105 return err < 0 ? err : 0;
106 }
107
108 const struct file_operations erofs_dir_fops = {
109 .llseek = generic_file_llseek,
110 .read = generic_read_dir,
111 .iterate_shared = erofs_readdir,
112 };
113