Root/lib/decompress.c

1/*
2 * decompress.c
3 *
4 * Detect the decompression method based on magic number
5 */
6
7#include <linux/decompress/generic.h>
8
9#include <linux/decompress/bunzip2.h>
10#include <linux/decompress/unlzma.h>
11#include <linux/decompress/inflate.h>
12#include <linux/decompress/unlzo.h>
13
14#include <linux/types.h>
15#include <linux/string.h>
16
17#ifndef CONFIG_DECOMPRESS_GZIP
18# define gunzip NULL
19#endif
20#ifndef CONFIG_DECOMPRESS_BZIP2
21# define bunzip2 NULL
22#endif
23#ifndef CONFIG_DECOMPRESS_LZMA
24# define unlzma NULL
25#endif
26#ifndef CONFIG_DECOMPRESS_LZO
27# define unlzo NULL
28#endif
29
30static const struct compress_format {
31    unsigned char magic[2];
32    const char *name;
33    decompress_fn decompressor;
34} compressed_formats[] = {
35    { {037, 0213}, "gzip", gunzip },
36    { {037, 0236}, "gzip", gunzip },
37    { {0x42, 0x5a}, "bzip2", bunzip2 },
38    { {0x5d, 0x00}, "lzma", unlzma },
39    { {0x89, 0x4c}, "lzo", unlzo },
40    { {0, 0}, NULL, NULL }
41};
42
43decompress_fn decompress_method(const unsigned char *inbuf, int len,
44                const char **name)
45{
46    const struct compress_format *cf;
47
48    if (len < 2)
49        return NULL; /* Need at least this much... */
50
51    for (cf = compressed_formats; cf->name; cf++) {
52        if (!memcmp(inbuf, cf->magic, 2))
53            break;
54
55    }
56    if (name)
57        *name = cf->name;
58    return cf->decompressor;
59}
60

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