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
|
#include <hilbert/kernel/storage/fs/tarfs.hpp>
//in tarfs_instance, node_id_t and directory_iter_t refer to the number
//of bytes into the block device that the info sector is located.
namespace hilbert::kernel::storage::fs {
#define BD_TO_FS(expr) \
{ \
bd_result _result = expr; \
if (_result == bd_result::out_of_bounds) \
return fs_result::fs_corrupt; \
if (_result == bd_result::device_error) \
return fs_result::device_error; \
}
#define FS_TO_FS(expr) \
{ \
fs_result _result = expr; \
if (_result != fs_result::success) \
return _result; \
}
tarfs_instance::tarfs_instance(block_device *bd) : bd(bd) {}
fs_result tarfs_instance::next_node(node_id_t node, node_id_t &out) {
uint64_t bytes;
FS_TO_FS(read_num(node + 124, 12, bytes))
out = node + ((bytes - 1) / 512 + 2) * 512;
uint8_t sector[512];
BD_TO_FS(bd->read_bytes(node, 512, sector))
for (unsigned i = 0; i < 512; ++i)
if (sector[i] != 0)
return fs_result::success;
return fs_result::does_not_exist;
}
fs_result tarfs_instance::read_full_name(
node_id_t node, utility::string &out
) {
out.count = 0;
out.verify_buffer_len(155);
BD_TO_FS(bd->read_bytes(node + 345, 155, out.buffer))
while (out.count < 155 && out.buffer[out.count] != '\0')
++out.count;
unsigned new_max = out.count + 100;
out.verify_buffer_len(new_max);
BD_TO_FS(bd->read_bytes(node, 100, out.buffer + out.count))
while (out.count < 255 && out.buffer[out.count] != '\0')
++out.count;
return fs_result::success;
}
//len <= 12.
fs_result tarfs_instance::read_num(
uint64_t offset, unsigned len, uint64_t &out
) {
char buf[12];
BD_TO_FS(bd->read_bytes(offset, len, buf))
out = 0;
for (unsigned i = 0; i < len && buf[i] != '\0'; ++i) {
if (buf[i] < '0' || buf[i] > '7')
return fs_result::fs_corrupt;
out = out * 8 + buf[i] - '0';
}
return fs_result::success;
}
fs_result tarfs_instance::first_child_starting_at(
node_id_t parent, node_id_t start, node_id_t &out
) {
utility::string parent_full_name;
FS_TO_FS(read_full_name(parent, parent_full_name))
utility::string child_full_name;
out = start;
while (true) {
FS_TO_FS(read_full_name(out, child_full_name))
if (child_full_name.count > parent_full_name.count &&
child_full_name.starts_with(parent_full_name)
) {
if (child_full_name.buffer[child_full_name.count - 1] == '/')
--child_full_name.count;
for (unsigned i = parent_full_name.count;
i < child_full_name.count; ++i)
if (child_full_name.buffer[i] == '/')
goto next;
return fs_result::success;
}
next:
FS_TO_FS(next_node(out, out))
}
}
fs_result tarfs_instance::get_dir_entry(node_id_t node, dir_entry &entry) {
utility::string full_name;
read_full_name(node, full_name);
if (full_name.count == 2)
entry.name.count = 0;
else {
if (full_name.buffer[full_name.count - 1] == '/')
--full_name.count;
unsigned last_slash =
utility::find_last(full_name.buffer, full_name.count, '/');
entry.name.count = full_name.count - last_slash - 1;
entry.name.verify_buffer_len(entry.name.count);
for (unsigned i = 0; i < entry.name.count; ++i)
entry.name.buffer[i] = full_name.buffer[last_slash + 1 + i];
}
entry.node = node;
char ch;
BD_TO_FS(bd->read_bytes(node + 156, 1, &ch));
switch (ch) {
case '0':
entry.type = file_type::regular_file;
break;
case '2':
entry.type = file_type::symlink;
break;
case '5':
entry.type = file_type::directory;
break;
default:
return fs_result::fs_corrupt;
}
if (entry.type == file_type::regular_file) {
uint64_t length;
FS_TO_FS(read_num(node + 124, 12, length))
entry.length = length;
}
else if (entry.type == file_type::symlink) {
utility::string target;
target.verify_buffer_len(100);
BD_TO_FS(bd->read_bytes(node + 157, 100, target.buffer))
while (target.count < 100 && target.buffer[target.count] != '\0')
++target.count;
entry.target = utility::move(target);
}
return fs_result::success;
}
fs_result tarfs_instance::get_root_node(node_id_t &out) {
utility::string full_name;
node_id_t on = 0;
while (true) {
FS_TO_FS(read_full_name(on, full_name))
if (full_name.count == 2) {
out = on;
return fs_result::success;
}
fs_result result = next_node(on, on);
if (result == fs_result::does_not_exist)
return fs_result::fs_corrupt;
FS_TO_FS(result)
}
}
fs_result tarfs_instance::get_first_child(
node_id_t node, dir_entry &out, directory_iter_t &iter_out
) {
node_id_t child;
FS_TO_FS(first_child_starting_at(node, 0, child))
dir_entry entry;
FS_TO_FS(get_dir_entry(child, entry))
out = utility::move(entry);
iter_out = (directory_iter_t)child;
return fs_result::success;
}
fs_result tarfs_instance::get_next_child(
node_id_t node, dir_entry &out, directory_iter_t &iter
) {
node_id_t start;
FS_TO_FS(next_node((node_id_t)iter, start))
node_id_t child;
FS_TO_FS(first_child_starting_at(node, start, child))
dir_entry entry;
FS_TO_FS(get_dir_entry(child, entry))
out = utility::move(entry);
iter = (directory_iter_t)child;
return fs_result::success;
}
fs_result tarfs_instance::read_bytes_from_file(
node_id_t node, uint64_t start, uint64_t count, void *into
) {
BD_TO_FS(bd->read_bytes(node + 512 + start, count, into))
return fs_result::success;
}
}
|