1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2017-2018 HUAWEI, Inc.
4*4882a593Smuzhiyun * https://www.huawei.com/
5*4882a593Smuzhiyun * Created by Gao Xiang <gaoxiang25@huawei.com>
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun #include "internal.h"
8*4882a593Smuzhiyun
debug_one_dentry(unsigned char d_type,const char * de_name,unsigned int de_namelen)9*4882a593Smuzhiyun static void debug_one_dentry(unsigned char d_type, const char *de_name,
10*4882a593Smuzhiyun unsigned int de_namelen)
11*4882a593Smuzhiyun {
12*4882a593Smuzhiyun #ifdef CONFIG_EROFS_FS_DEBUG
13*4882a593Smuzhiyun /* since the on-disk name could not have the trailing '\0' */
14*4882a593Smuzhiyun unsigned char dbg_namebuf[EROFS_NAME_LEN + 1];
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun memcpy(dbg_namebuf, de_name, de_namelen);
17*4882a593Smuzhiyun dbg_namebuf[de_namelen] = '\0';
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf,
20*4882a593Smuzhiyun de_namelen, d_type);
21*4882a593Smuzhiyun #endif
22*4882a593Smuzhiyun }
23*4882a593Smuzhiyun
erofs_fill_dentries(struct inode * dir,struct dir_context * ctx,void * dentry_blk,unsigned int * ofs,unsigned int nameoff,unsigned int maxsize)24*4882a593Smuzhiyun static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
25*4882a593Smuzhiyun void *dentry_blk, unsigned int *ofs,
26*4882a593Smuzhiyun unsigned int nameoff, unsigned int maxsize)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun struct erofs_dirent *de = dentry_blk + *ofs;
29*4882a593Smuzhiyun const struct erofs_dirent *end = dentry_blk + nameoff;
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun while (de < end) {
32*4882a593Smuzhiyun const char *de_name;
33*4882a593Smuzhiyun unsigned int de_namelen;
34*4882a593Smuzhiyun unsigned char d_type;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun d_type = fs_ftype_to_dtype(de->file_type);
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun nameoff = le16_to_cpu(de->nameoff);
39*4882a593Smuzhiyun de_name = (char *)dentry_blk + nameoff;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun /* the last dirent in the block? */
42*4882a593Smuzhiyun if (de + 1 >= end)
43*4882a593Smuzhiyun de_namelen = strnlen(de_name, maxsize - nameoff);
44*4882a593Smuzhiyun else
45*4882a593Smuzhiyun de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun /* a corrupted entry is found */
48*4882a593Smuzhiyun if (nameoff + de_namelen > maxsize ||
49*4882a593Smuzhiyun de_namelen > EROFS_NAME_LEN) {
50*4882a593Smuzhiyun erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
51*4882a593Smuzhiyun EROFS_I(dir)->nid);
52*4882a593Smuzhiyun DBG_BUGON(1);
53*4882a593Smuzhiyun return -EFSCORRUPTED;
54*4882a593Smuzhiyun }
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun debug_one_dentry(d_type, de_name, de_namelen);
57*4882a593Smuzhiyun if (!dir_emit(ctx, de_name, de_namelen,
58*4882a593Smuzhiyun le64_to_cpu(de->nid), d_type))
59*4882a593Smuzhiyun /* stopped by some reason */
60*4882a593Smuzhiyun return 1;
61*4882a593Smuzhiyun ++de;
62*4882a593Smuzhiyun *ofs += sizeof(struct erofs_dirent);
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun *ofs = maxsize;
65*4882a593Smuzhiyun return 0;
66*4882a593Smuzhiyun }
67*4882a593Smuzhiyun
erofs_readdir(struct file * f,struct dir_context * ctx)68*4882a593Smuzhiyun static int erofs_readdir(struct file *f, struct dir_context *ctx)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun struct inode *dir = file_inode(f);
71*4882a593Smuzhiyun struct address_space *mapping = dir->i_mapping;
72*4882a593Smuzhiyun const size_t dirsize = i_size_read(dir);
73*4882a593Smuzhiyun unsigned int i = ctx->pos / EROFS_BLKSIZ;
74*4882a593Smuzhiyun unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
75*4882a593Smuzhiyun int err = 0;
76*4882a593Smuzhiyun bool initial = true;
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun while (ctx->pos < dirsize) {
79*4882a593Smuzhiyun struct page *dentry_page;
80*4882a593Smuzhiyun struct erofs_dirent *de;
81*4882a593Smuzhiyun unsigned int nameoff, maxsize;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun dentry_page = read_mapping_page(mapping, i, NULL);
84*4882a593Smuzhiyun if (dentry_page == ERR_PTR(-ENOMEM)) {
85*4882a593Smuzhiyun err = -ENOMEM;
86*4882a593Smuzhiyun break;
87*4882a593Smuzhiyun } else if (IS_ERR(dentry_page)) {
88*4882a593Smuzhiyun erofs_err(dir->i_sb,
89*4882a593Smuzhiyun "fail to readdir of logical block %u of nid %llu",
90*4882a593Smuzhiyun i, EROFS_I(dir)->nid);
91*4882a593Smuzhiyun err = -EFSCORRUPTED;
92*4882a593Smuzhiyun break;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun de = (struct erofs_dirent *)kmap(dentry_page);
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun nameoff = le16_to_cpu(de->nameoff);
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun if (nameoff < sizeof(struct erofs_dirent) ||
100*4882a593Smuzhiyun nameoff >= PAGE_SIZE) {
101*4882a593Smuzhiyun erofs_err(dir->i_sb,
102*4882a593Smuzhiyun "invalid de[0].nameoff %u @ nid %llu",
103*4882a593Smuzhiyun nameoff, EROFS_I(dir)->nid);
104*4882a593Smuzhiyun err = -EFSCORRUPTED;
105*4882a593Smuzhiyun goto skip_this;
106*4882a593Smuzhiyun }
107*4882a593Smuzhiyun
108*4882a593Smuzhiyun maxsize = min_t(unsigned int,
109*4882a593Smuzhiyun dirsize - ctx->pos + ofs, PAGE_SIZE);
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun /* search dirents at the arbitrary position */
112*4882a593Smuzhiyun if (initial) {
113*4882a593Smuzhiyun initial = false;
114*4882a593Smuzhiyun
115*4882a593Smuzhiyun ofs = roundup(ofs, sizeof(struct erofs_dirent));
116*4882a593Smuzhiyun if (ofs >= nameoff)
117*4882a593Smuzhiyun goto skip_this;
118*4882a593Smuzhiyun }
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun err = erofs_fill_dentries(dir, ctx, de, &ofs,
121*4882a593Smuzhiyun nameoff, maxsize);
122*4882a593Smuzhiyun skip_this:
123*4882a593Smuzhiyun kunmap(dentry_page);
124*4882a593Smuzhiyun
125*4882a593Smuzhiyun put_page(dentry_page);
126*4882a593Smuzhiyun
127*4882a593Smuzhiyun ctx->pos = blknr_to_addr(i) + ofs;
128*4882a593Smuzhiyun
129*4882a593Smuzhiyun if (err)
130*4882a593Smuzhiyun break;
131*4882a593Smuzhiyun ++i;
132*4882a593Smuzhiyun ofs = 0;
133*4882a593Smuzhiyun }
134*4882a593Smuzhiyun return err < 0 ? err : 0;
135*4882a593Smuzhiyun }
136*4882a593Smuzhiyun
137*4882a593Smuzhiyun const struct file_operations erofs_dir_fops = {
138*4882a593Smuzhiyun .llseek = generic_file_llseek,
139*4882a593Smuzhiyun .read = generic_read_dir,
140*4882a593Smuzhiyun .iterate_shared = erofs_readdir,
141*4882a593Smuzhiyun };
142*4882a593Smuzhiyun
143