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
|
/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
* meta_reader.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#define SQFS_BUILDING_DLL
#include "config.h"
#include "sqfs/meta_reader.h"
#include "sqfs/compress.h"
#include "sqfs/error.h"
#include "sqfs/data.h"
#include "sqfs/io.h"
#include "util.h"
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
struct sqfs_meta_reader_t {
uint64_t start;
uint64_t limit;
size_t data_used;
/* The location of the current block in the image */
uint64_t block_offset;
/* The location of the next block after the current one */
uint64_t next_block;
/* A byte offset into the uncompressed data of the current block */
size_t offset;
/* The underlying file descriptor to read from */
sqfs_file_t *file;
/* A pointer to the compressor to use for extracting data */
sqfs_compressor_t *cmp;
/* The raw data read from the input file */
uint8_t data[SQFS_META_BLOCK_SIZE];
/* The uncompressed data read from the input file */
uint8_t scratch[SQFS_META_BLOCK_SIZE];
};
sqfs_meta_reader_t *sqfs_meta_reader_create(sqfs_file_t *file,
sqfs_compressor_t *cmp,
uint64_t start, uint64_t limit)
{
sqfs_meta_reader_t *m = calloc(1, sizeof(*m));
if (m == NULL)
return NULL;
m->start = start;
m->limit = limit;
m->file = file;
m->cmp = cmp;
return m;
}
void sqfs_meta_reader_destroy(sqfs_meta_reader_t *m)
{
free(m);
}
int sqfs_meta_reader_seek(sqfs_meta_reader_t *m, uint64_t block_start,
size_t offset)
{
bool compressed;
uint16_t header;
ssize_t ret;
size_t size;
int err;
if (block_start < m->start || block_start >= m->limit)
return SQFS_ERROR_OUT_OF_BOUNDS;
if (block_start == m->block_offset) {
if (offset >= m->data_used)
return SQFS_ERROR_OUT_OF_BOUNDS;
m->offset = offset;
return 0;
}
err = m->file->read_at(m->file, block_start, &header, 2);
if (err)
return err;
header = le16toh(header);
compressed = (header & 0x8000) == 0;
size = header & 0x7FFF;
if (size > sizeof(m->data))
return SQFS_ERROR_CORRUPTED;
if ((block_start + 2 + size) > m->limit)
return SQFS_ERROR_OUT_OF_BOUNDS;
err = m->file->read_at(m->file, block_start + 2, m->data, size);
if (err)
return err;
if (compressed) {
ret = m->cmp->do_block(m->cmp, m->data, size,
m->scratch, sizeof(m->scratch));
if (ret < 0)
return ret;
memcpy(m->data, m->scratch, ret);
m->data_used = ret;
} else {
m->data_used = size;
}
if (offset >= m->data_used)
return SQFS_ERROR_OUT_OF_BOUNDS;
m->block_offset = block_start;
m->next_block = block_start + size + 2;
m->offset = offset;
return 0;
}
void sqfs_meta_reader_get_position(const sqfs_meta_reader_t *m,
uint64_t *block_start, size_t *offset)
{
*block_start = m->block_offset;
*offset = m->offset;
}
int sqfs_meta_reader_read(sqfs_meta_reader_t *m, void *data, size_t size)
{
size_t diff;
int ret;
while (size != 0) {
diff = m->data_used - m->offset;
if (diff == 0) {
ret = sqfs_meta_reader_seek(m, m->next_block, 0);
if (ret)
return ret;
diff = m->data_used;
}
if (diff > size)
diff = size;
memcpy(data, m->data + m->offset, diff);
m->offset += diff;
data = (char *)data + diff;
size -= diff;
}
return 0;
}
|
