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
|
/* SPDX-License-Identifier: GPL-3.0-or-later */
#include "meta_reader.h"
#include "util.h"
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
meta_reader_t *meta_reader_create(int fd, compressor_t *cmp)
{
meta_reader_t *m = calloc(1, sizeof(*m));
if (m == NULL) {
perror("creating meta data reader");
return NULL;
}
m->fd = fd;
m->cmp = cmp;
return m;
}
void meta_reader_destroy(meta_reader_t *m)
{
free(m);
}
int meta_reader_seek(meta_reader_t *m, uint64_t block_start, size_t offset)
{
bool compressed;
uint16_t header;
ssize_t ret;
size_t size;
if (offset >= sizeof(m->data)) {
fputs("Tried to seek past end of meta data block.\n", stderr);
return -1;
}
if (block_start == m->block_offset) {
m->offset = offset;
return 0;
}
if (lseek(m->fd, block_start, SEEK_SET) == (off_t)-1) {
perror("seek on image file");
return -1;
}
ret = read_retry(m->fd, &header, 2);
if (ret < 0)
goto fail_rd;
if ((size_t)ret < 2)
goto fail_trunc;
header = le16toh(header);
compressed = (header & 0x8000) == 0;
size = header & 0x7FFF;
if (size > sizeof(m->data)) {
fputs("found meta data block larger than maximum size\n",
stderr);
return -1;
}
m->block_offset = block_start;
m->offset = offset;
m->next_block = block_start + size + 2;
memset(m->data, 0, sizeof(m->data));
ret = read_retry(m->fd, m->data, size);
if (ret < 0)
goto fail_rd;
if ((size_t)ret < size)
goto fail_trunc;
if (compressed) {
ret = m->cmp->do_block(m->cmp, m->data, size);
if (ret <= 0) {
fputs("error uncompressing meta data block\n", stderr);
return -1;
}
}
return 0;
fail_trunc:
fputs("reading meta data: unexpected end of file\n", stderr);
return -1;
fail_rd:
perror("reading meta data");
return -1;
}
int meta_reader_read(meta_reader_t *m, void *data, size_t size)
{
size_t diff;
while (size != 0) {
diff = sizeof(m->data) - m->offset;
if (diff == 0) {
if (meta_reader_seek(m, m->next_block, 0))
return -1;
diff = sizeof(m->data);
}
if (diff > size)
diff = size;
memcpy(data, m->data + m->offset, diff);
m->offset += diff;
data = (char *)data + diff;
size -= diff;
}
return 0;
}
|
