1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/drivers/staging/erofs/dir.c
4 *
5 * Copyright (C) 2017-2018 HUAWEI, Inc.
6 * http://www.huawei.com/
7 * Created by Gao Xiang <gaoxiang25@huawei.com>
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License. See the file COPYING in the main directory of the Linux
11 * distribution for more details.
12 */
13 #include "internal.h"
14
15 static const unsigned char erofs_filetype_table[EROFS_FT_MAX] = {
16 [EROFS_FT_UNKNOWN] = DT_UNKNOWN,
17 [EROFS_FT_REG_FILE] = DT_REG,
18 [EROFS_FT_DIR] = DT_DIR,
19 [EROFS_FT_CHRDEV] = DT_CHR,
20 [EROFS_FT_BLKDEV] = DT_BLK,
21 [EROFS_FT_FIFO] = DT_FIFO,
22 [EROFS_FT_SOCK] = DT_SOCK,
23 [EROFS_FT_SYMLINK] = DT_LNK,
24 };
25
erofs_fill_dentries(struct dir_context * ctx,void * dentry_blk,unsigned * ofs,unsigned nameoff,unsigned maxsize)26 static int erofs_fill_dentries(struct dir_context *ctx,
27 void *dentry_blk, unsigned *ofs,
28 unsigned nameoff, unsigned maxsize)
29 {
30 struct erofs_dirent *de = dentry_blk;
31 const struct erofs_dirent *end = dentry_blk + nameoff;
32
33 de = dentry_blk + *ofs;
34 while (de < end) {
35 const char *de_name;
36 int de_namelen;
37 unsigned char d_type;
38 #ifdef CONFIG_EROFS_FS_DEBUG
39 unsigned dbg_namelen;
40 unsigned char dbg_namebuf[EROFS_NAME_LEN];
41 #endif
42
43 if (unlikely(de->file_type < EROFS_FT_MAX))
44 d_type = erofs_filetype_table[de->file_type];
45 else
46 d_type = DT_UNKNOWN;
47
48 nameoff = le16_to_cpu(de->nameoff);
49 de_name = (char *)dentry_blk + nameoff;
50
51 de_namelen = unlikely(de + 1 >= end) ?
52 /* last directory entry */
53 strnlen(de_name, maxsize - nameoff) :
54 le16_to_cpu(de[1].nameoff) - nameoff;
55
56 /* the corrupted directory found */
57 BUG_ON(de_namelen < 0);
58
59 #ifdef CONFIG_EROFS_FS_DEBUG
60 dbg_namelen = min(EROFS_NAME_LEN - 1, de_namelen);
61 memcpy(dbg_namebuf, de_name, dbg_namelen);
62 dbg_namebuf[dbg_namelen] = '\0';
63
64 debugln("%s, found de_name %s de_len %d d_type %d", __func__,
65 dbg_namebuf, de_namelen, d_type);
66 #endif
67
68 if (!dir_emit(ctx, de_name, de_namelen,
69 le64_to_cpu(de->nid), d_type))
70 /* stoped by some reason */
71 return 1;
72 ++de;
73 *ofs += sizeof(struct erofs_dirent);
74 }
75 *ofs = maxsize;
76 return 0;
77 }
78
erofs_readdir(struct file * f,struct dir_context * ctx)79 static int erofs_readdir(struct file *f, struct dir_context *ctx)
80 {
81 struct inode *dir = file_inode(f);
82 struct address_space *mapping = dir->i_mapping;
83 const size_t dirsize = i_size_read(dir);
84 unsigned i = ctx->pos / EROFS_BLKSIZ;
85 unsigned ofs = ctx->pos % EROFS_BLKSIZ;
86 int err = 0;
87 bool initial = true;
88
89 while (ctx->pos < dirsize) {
90 struct page *dentry_page;
91 struct erofs_dirent *de;
92 unsigned nameoff, maxsize;
93
94 dentry_page = read_mapping_page(mapping, i, NULL);
95 if (IS_ERR(dentry_page))
96 continue;
97
98 lock_page(dentry_page);
99 de = (struct erofs_dirent *)kmap(dentry_page);
100
101 nameoff = le16_to_cpu(de->nameoff);
102
103 if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
104 nameoff >= PAGE_SIZE)) {
105 errln("%s, invalid de[0].nameoff %u",
106 __func__, nameoff);
107
108 err = -EIO;
109 goto skip_this;
110 }
111
112 maxsize = min_t(unsigned, dirsize - ctx->pos + ofs, PAGE_SIZE);
113
114 /* search dirents at the arbitrary position */
115 if (unlikely(initial)) {
116 initial = false;
117
118 ofs = roundup(ofs, sizeof(struct erofs_dirent));
119 if (unlikely(ofs >= nameoff))
120 goto skip_this;
121 }
122
123 err = erofs_fill_dentries(ctx, de, &ofs, nameoff, maxsize);
124 skip_this:
125 kunmap(dentry_page);
126
127 unlock_page(dentry_page);
128 put_page(dentry_page);
129
130 ctx->pos = blknr_to_addr(i) + ofs;
131
132 if (unlikely(err))
133 break;
134 ++i;
135 ofs = 0;
136 }
137 return err < 0 ? err : 0;
138 }
139
140 const struct file_operations erofs_dir_fops = {
141 .llseek = generic_file_llseek,
142 .read = generic_read_dir,
143 .iterate = erofs_readdir,
144 };
145
146
