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/unxz.h>
12#include <linux/decompress/inflate.h>
13#include <linux/decompress/unlzo.h>
14#include <linux/decompress/unlz4.h>
15
16#include <linux/types.h>
17#include <linux/string.h>
18#include <linux/init.h>
19
20#ifndef CONFIG_DECOMPRESS_GZIP
21# define gunzip NULL
22#endif
23#ifndef CONFIG_DECOMPRESS_BZIP2
24# define bunzip2 NULL
25#endif
26#ifndef CONFIG_DECOMPRESS_LZMA
27# define unlzma NULL
28#endif
29#ifndef CONFIG_DECOMPRESS_XZ
30# define unxz NULL
31#endif
32#ifndef CONFIG_DECOMPRESS_LZO
33# define unlzo NULL
34#endif
35#ifndef CONFIG_DECOMPRESS_LZ4
36# define unlz4 NULL
37#endif
38
39struct compress_format {
40    unsigned char magic[2];
41    const char *name;
42    decompress_fn decompressor;
43};
44
45static const struct compress_format compressed_formats[] __initconst = {
46    { {037, 0213}, "gzip", gunzip },
47    { {037, 0236}, "gzip", gunzip },
48    { {0x42, 0x5a}, "bzip2", bunzip2 },
49    { {0x5d, 0x00}, "lzma", unlzma },
50    { {0xfd, 0x37}, "xz", unxz },
51    { {0x89, 0x4c}, "lzo", unlzo },
52    { {0x02, 0x21}, "lz4", unlz4 },
53    { {0, 0}, NULL, NULL }
54};
55
56decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
57                const char **name)
58{
59    const struct compress_format *cf;
60
61    if (len < 2)
62        return NULL; /* Need at least this much... */
63
64    for (cf = compressed_formats; cf->name; cf++) {
65        if (!memcmp(inbuf, cf->magic, 2))
66            break;
67
68    }
69    if (name)
70        *name = cf->name;
71    return cf->decompressor;
72}
73

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