forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
dir.c
281 lines (249 loc) · 6.71 KB
/
dir.c
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
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/*
* QNX6 file system, Linux implementation.
*
* Version : 1.0.0
*
* History :
*
* 01-02-2012 by Kai Bankett ([email protected]) : first release.
* 16-02-2012 pagemap extension by Al Viro
*
*/
#include "qnx6.h"
static unsigned qnx6_lfile_checksum(char *name, unsigned size)
{
unsigned crc = 0;
char *end = name + size;
while (name < end) {
crc = ((crc >> 1) + *(name++)) ^
((crc & 0x00000001) ? 0x80000000 : 0);
}
return crc;
}
static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
{
struct address_space *mapping = dir->i_mapping;
struct page *page = read_mapping_page(mapping, n, NULL);
if (!IS_ERR(page))
kmap(page);
return page;
}
static unsigned last_entry(struct inode *inode, unsigned long page_nr)
{
unsigned long last_byte = inode->i_size;
last_byte -= page_nr << PAGE_SHIFT;
if (last_byte > PAGE_SIZE)
last_byte = PAGE_SIZE;
return last_byte / QNX6_DIR_ENTRY_SIZE;
}
static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
struct qnx6_long_dir_entry *de,
struct page **p)
{
struct qnx6_sb_info *sbi = QNX6_SB(sb);
u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */
/* within page */
u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_MASK;
struct address_space *mapping = sbi->longfile->i_mapping;
struct page *page = read_mapping_page(mapping, n, NULL);
if (IS_ERR(page))
return ERR_CAST(page);
kmap(*p = page);
return (struct qnx6_long_filename *)(page_address(page) + offs);
}
static int qnx6_dir_longfilename(struct inode *inode,
struct qnx6_long_dir_entry *de,
struct dir_context *ctx,
unsigned de_inode)
{
struct qnx6_long_filename *lf;
struct super_block *s = inode->i_sb;
struct qnx6_sb_info *sbi = QNX6_SB(s);
struct page *page;
int lf_size;
if (de->de_size != 0xff) {
/* error - long filename entries always have size 0xff
in direntry */
pr_err("invalid direntry size (%i).\n", de->de_size);
return 0;
}
lf = qnx6_longname(s, de, &page);
if (IS_ERR(lf)) {
pr_err("Error reading longname\n");
return 0;
}
lf_size = fs16_to_cpu(sbi, lf->lf_size);
if (lf_size > QNX6_LONG_NAME_MAX) {
pr_debug("file %s\n", lf->lf_fname);
pr_err("Filename too long (%i)\n", lf_size);
qnx6_put_page(page);
return 0;
}
/* calc & validate longfilename checksum
mmi 3g filesystem does not have that checksum */
if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
qnx6_lfile_checksum(lf->lf_fname, lf_size))
pr_info("long filename checksum error.\n");
pr_debug("qnx6_readdir:%.*s inode:%u\n",
lf_size, lf->lf_fname, de_inode);
if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
qnx6_put_page(page);
return 0;
}
qnx6_put_page(page);
/* success */
return 1;
}
static int qnx6_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
struct super_block *s = inode->i_sb;
struct qnx6_sb_info *sbi = QNX6_SB(s);
loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
unsigned long npages = dir_pages(inode);
unsigned long n = pos >> PAGE_SHIFT;
unsigned start = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE;
bool done = false;
ctx->pos = pos;
if (ctx->pos >= inode->i_size)
return 0;
for ( ; !done && n < npages; n++, start = 0) {
struct page *page = qnx6_get_page(inode, n);
int limit = last_entry(inode, n);
struct qnx6_dir_entry *de;
int i = start;
if (IS_ERR(page)) {
pr_err("%s(): read failed\n", __func__);
ctx->pos = (n + 1) << PAGE_SHIFT;
return PTR_ERR(page);
}
de = ((struct qnx6_dir_entry *)page_address(page)) + start;
for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
int size = de->de_size;
u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
if (!no_inode || !size)
continue;
if (size > QNX6_SHORT_NAME_MAX) {
/* long filename detected
get the filename from long filename
structure / block */
if (!qnx6_dir_longfilename(inode,
(struct qnx6_long_dir_entry *)de,
ctx, no_inode)) {
done = true;
break;
}
} else {
pr_debug("%s():%.*s inode:%u\n",
__func__, size, de->de_fname,
no_inode);
if (!dir_emit(ctx, de->de_fname, size,
no_inode, DT_UNKNOWN)) {
done = true;
break;
}
}
}
qnx6_put_page(page);
}
return 0;
}
/*
* check if the long filename is correct.
*/
static unsigned qnx6_long_match(int len, const char *name,
struct qnx6_long_dir_entry *de, struct inode *dir)
{
struct super_block *s = dir->i_sb;
struct qnx6_sb_info *sbi = QNX6_SB(s);
struct page *page;
int thislen;
struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
if (IS_ERR(lf))
return 0;
thislen = fs16_to_cpu(sbi, lf->lf_size);
if (len != thislen) {
qnx6_put_page(page);
return 0;
}
if (memcmp(name, lf->lf_fname, len) == 0) {
qnx6_put_page(page);
return fs32_to_cpu(sbi, de->de_inode);
}
qnx6_put_page(page);
return 0;
}
/*
* check if the filename is correct.
*/
static unsigned qnx6_match(struct super_block *s, int len, const char *name,
struct qnx6_dir_entry *de)
{
struct qnx6_sb_info *sbi = QNX6_SB(s);
if (memcmp(name, de->de_fname, len) == 0)
return fs32_to_cpu(sbi, de->de_inode);
return 0;
}
unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
struct page **res_page)
{
struct super_block *s = dir->i_sb;
struct qnx6_inode_info *ei = QNX6_I(dir);
struct page *page = NULL;
unsigned long start, n;
unsigned long npages = dir_pages(dir);
unsigned ino;
struct qnx6_dir_entry *de;
struct qnx6_long_dir_entry *lde;
*res_page = NULL;
if (npages == 0)
return 0;
start = ei->i_dir_start_lookup;
if (start >= npages)
start = 0;
n = start;
do {
page = qnx6_get_page(dir, n);
if (!IS_ERR(page)) {
int limit = last_entry(dir, n);
int i;
de = (struct qnx6_dir_entry *)page_address(page);
for (i = 0; i < limit; i++, de++) {
if (len <= QNX6_SHORT_NAME_MAX) {
/* short filename */
if (len != de->de_size)
continue;
ino = qnx6_match(s, len, name, de);
if (ino)
goto found;
} else if (de->de_size == 0xff) {
/* deal with long filename */
lde = (struct qnx6_long_dir_entry *)de;
ino = qnx6_long_match(len,
name, lde, dir);
if (ino)
goto found;
} else
pr_err("undefined filename size in inode.\n");
}
qnx6_put_page(page);
}
if (++n >= npages)
n = 0;
} while (n != start);
return 0;
found:
*res_page = page;
ei->i_dir_start_lookup = n;
return ino;
}
const struct file_operations qnx6_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = qnx6_readdir,
.fsync = generic_file_fsync,
};
const struct inode_operations qnx6_dir_inode_operations = {
.lookup = qnx6_lookup,
};