1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
#include "internal.h"
static void debug_one_dentry(unsigned char d_type, const char *de_name,
unsigned int de_namelen)
{
#ifdef CONFIG_EROFS_FS_DEBUG
/* since the on-disk name could not have the trailing '\0' */
unsigned char dbg_namebuf[EROFS_NAME_LEN + 1];
memcpy(dbg_namebuf, de_name, de_namelen);
dbg_namebuf[de_namelen] = '\0';
debugln("found dirent %s de_len %u d_type %d", dbg_namebuf,
de_namelen, d_type);
#endif
}
static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
void *dentry_blk, unsigned int *ofs,
unsigned int nameoff, unsigned int maxsize)
{
struct erofs_dirent *de = dentry_blk + *ofs;
const struct erofs_dirent *end = dentry_blk + nameoff;
while (de < end) {
const char *de_name;
unsigned int de_namelen;
unsigned char d_type;
d_type = fs_ftype_to_dtype(de->file_type);
nameoff = le16_to_cpu(de->nameoff);
de_name = (char *)dentry_blk + nameoff;
/* the last dirent in the block? */
if (de + 1 >= end)
de_namelen = strnlen(de_name, maxsize - nameoff);
else
de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
/* a corrupted entry is found */
if (unlikely(nameoff + de_namelen > maxsize ||
de_namelen > EROFS_NAME_LEN)) {
errln("bogus dirent @ nid %llu", EROFS_V(dir)->nid);
DBG_BUGON(1);
return -EFSCORRUPTED;
}
debug_one_dentry(d_type, de_name, de_namelen);
if (!dir_emit(ctx, de_name, de_namelen,
le64_to_cpu(de->nid), d_type))
/* stopped by some reason */
return 1;
++de;
*ofs += sizeof(struct erofs_dirent);
}
*ofs = maxsize;
return 0;
}
static int erofs_readdir(struct file *f, struct dir_context *ctx)
{
struct inode *dir = file_inode(f);
struct address_space *mapping = dir->i_mapping;
const size_t dirsize = i_size_read(dir);
unsigned int i = ctx->pos / EROFS_BLKSIZ;
unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
int err = 0;
bool initial = true;
while (ctx->pos < dirsize) {
struct page *dentry_page;
struct erofs_dirent *de;
unsigned int nameoff, maxsize;
dentry_page = read_mapping_page(mapping, i, NULL);
if (dentry_page == ERR_PTR(-ENOMEM)) {
err = -ENOMEM;
break;
} else if (IS_ERR(dentry_page)) {
errln("fail to readdir of logical block %u of nid %llu",
i, EROFS_V(dir)->nid);
err = -EFSCORRUPTED;
break;
}
de = (struct erofs_dirent *)kmap(dentry_page);
nameoff = le16_to_cpu(de->nameoff);
if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
nameoff >= PAGE_SIZE)) {
errln("%s, invalid de[0].nameoff %u @ nid %llu",
__func__, nameoff, EROFS_V(dir)->nid);
err = -EFSCORRUPTED;
goto skip_this;
}
maxsize = min_t(unsigned int,
dirsize - ctx->pos + ofs, PAGE_SIZE);
/* search dirents at the arbitrary position */
if (unlikely(initial)) {
initial = false;
ofs = roundup(ofs, sizeof(struct erofs_dirent));
if (unlikely(ofs >= nameoff))
goto skip_this;
}
err = erofs_fill_dentries(dir, ctx, de, &ofs,
nameoff, maxsize);
skip_this:
kunmap(dentry_page);
put_page(dentry_page);
ctx->pos = blknr_to_addr(i) + ofs;
if (unlikely(err))
break;
++i;
ofs = 0;
}
return err < 0 ? err : 0;
}
const struct file_operations erofs_dir_fops = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = erofs_readdir,
};
|
