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
|
/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* autodetect.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#include "../internal.h"
static const struct {
int id;
const sqfs_u8 *value;
size_t len;
} magic[] = {
{ FSTREAM_COMPRESSOR_GZIP, (const sqfs_u8 *)"\x1F\x8B\x08", 3 },
{ FSTREAM_COMPRESSOR_XZ, (const sqfs_u8 *)("\xFD" "7zXZ"), 6 },
{ FSTREAM_COMPRESSOR_ZSTD, (const sqfs_u8 *)"\x28\xB5\x2F\xFD", 4 },
};
int istream_detect_compressor(istream_t *strm,
int (*probe)(const sqfs_u8 *data, size_t size))
{
size_t i;
int ret;
ret = istream_precache(strm);
if (ret != 0)
return ret;
if (probe != NULL) {
ret = probe(strm->buffer + strm->buffer_offset,
strm->buffer_used - strm->buffer_offset);
if (ret < 0)
return ret;
/* XXX: this means the data is uncompressed. We do this check
first since it might be perfectly OK for the uncompressed
data to contain a magic number from the table. */
if (ret > 0)
return 0;
}
for (i = 0; i < sizeof(magic) / sizeof(magic[0]); ++i) {
if ((strm->buffer_used - strm->buffer_offset) < magic[i].len)
continue;
ret = memcmp(strm->buffer + strm->buffer_offset,
magic[i].value, magic[i].len);
if (ret == 0)
return magic[i].id;
}
return 0;
}
|
