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
debug_one_dentry(unsigned char d_type,const char * de_name,unsigned int de_namelen)9 static void debug_one_dentry(unsigned char d_type, const char *de_name,
10 unsigned int de_namelen)
11 {
12 #ifdef CONFIG_EROFS_FS_DEBUG
13 /* since the on-disk name could not have the trailing '\0' */
14 unsigned char dbg_namebuf[EROFS_NAME_LEN + 1];
15
16 memcpy(dbg_namebuf, de_name, de_namelen);
17 dbg_namebuf[de_namelen] = '\0';
18
19 erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf,
20 de_namelen, d_type);
21 #endif
22 }
23
erofs_fill_dentries(struct inode * dir,struct dir_context * ctx,void * dentry_blk,struct erofs_dirent * de,unsigned int nameoff,unsigned int maxsize)24 static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
25 void *dentry_blk, struct erofs_dirent *de,
26 unsigned int nameoff, unsigned int maxsize)
27 {
28 const struct erofs_dirent *end = dentry_blk + nameoff;
29
30 while (de < end) {
31 const char *de_name;
32 unsigned int de_namelen;
33 unsigned char d_type;
34
35 d_type = fs_ftype_to_dtype(de->file_type);
36
37 nameoff = le16_to_cpu(de->nameoff);
38 de_name = (char *)dentry_blk + nameoff;
39
40 /* the last dirent in the block? */
41 if (de + 1 >= end)
42 de_namelen = strnlen(de_name, maxsize - nameoff);
43 else
44 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
45
46 /* a corrupted entry is found */
47 if (nameoff + de_namelen > maxsize ||
48 de_namelen > EROFS_NAME_LEN) {
49 erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
50 EROFS_I(dir)->nid);
51 DBG_BUGON(1);
52 return -EFSCORRUPTED;
53 }
54
55 debug_one_dentry(d_type, de_name, de_namelen);
56 if (!dir_emit(ctx, de_name, de_namelen,
57 le64_to_cpu(de->nid), d_type))
58 /* stopped by some reason */
59 return 1;
60 ++de;
61 ctx->pos += sizeof(struct erofs_dirent);
62 }
63 return 0;
64 }
65
erofs_readdir(struct file * f,struct dir_context * ctx)66 static int erofs_readdir(struct file *f, struct dir_context *ctx)
67 {
68 struct inode *dir = file_inode(f);
69 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
70 struct super_block *sb = dir->i_sb;
71 unsigned long bsz = sb->s_blocksize;
72 const size_t dirsize = i_size_read(dir);
73 unsigned int i = erofs_blknr(sb, ctx->pos);
74 unsigned int ofs = erofs_blkoff(sb, ctx->pos);
75 int err = 0;
76 bool initial = true;
77
78 while (ctx->pos < dirsize) {
79 struct erofs_dirent *de;
80 unsigned int nameoff, maxsize;
81
82 de = erofs_bread(&buf, dir, i, EROFS_KMAP);
83 if (IS_ERR(de)) {
84 erofs_err(sb, "fail to readdir of logical block %u of nid %llu",
85 i, EROFS_I(dir)->nid);
86 err = PTR_ERR(de);
87 break;
88 }
89
90 nameoff = le16_to_cpu(de->nameoff);
91 if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) {
92 erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",
93 nameoff, EROFS_I(dir)->nid);
94 err = -EFSCORRUPTED;
95 break;
96 }
97
98 maxsize = min_t(unsigned int, dirsize - ctx->pos + ofs, bsz);
99
100 /* search dirents at the arbitrary position */
101 if (initial) {
102 initial = false;
103
104 ofs = roundup(ofs, sizeof(struct erofs_dirent));
105 ctx->pos = erofs_pos(sb, i) + ofs;
106 if (ofs >= nameoff)
107 goto skip_this;
108 }
109
110 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
111 nameoff, maxsize);
112 if (err)
113 break;
114 skip_this:
115 ctx->pos = erofs_pos(sb, i) + maxsize;
116 ++i;
117 ofs = 0;
118 }
119 erofs_put_metabuf(&buf);
120 return err < 0 ? err : 0;
121 }
122
123 const struct file_operations erofs_dir_fops = {
124 .llseek = generic_file_llseek,
125 .read = generic_read_dir,
126 .iterate_shared = erofs_readdir,
127 };
128