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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 | #include <linux/printk.h> | |
20 | ||
21 | #ifndef CONFIG_DECOMPRESS_GZIP | |
22 | # define gunzip NULL | |
23 | #endif | |
24 | #ifndef CONFIG_DECOMPRESS_BZIP2 | |
25 | # define bunzip2 NULL | |
26 | #endif | |
27 | #ifndef CONFIG_DECOMPRESS_LZMA | |
28 | # define unlzma NULL | |
29 | #endif | |
30 | #ifndef CONFIG_DECOMPRESS_XZ | |
31 | # define unxz NULL | |
32 | #endif | |
33 | #ifndef CONFIG_DECOMPRESS_LZO | |
34 | # define unlzo NULL | |
35 | #endif | |
36 | #ifndef CONFIG_DECOMPRESS_LZ4 | |
37 | # define unlz4 NULL | |
38 | #endif | |
39 | ||
40 | struct compress_format { | |
41 | unsigned char magic[2]; | |
42 | const char *name; | |
43 | decompress_fn decompressor; | |
44 | }; | |
45 | ||
46 | static const struct compress_format compressed_formats[] __initconst = { | |
47 | { {0x1f, 0x8b}, "gzip", gunzip }, | |
48 | { {0x1f, 0x9e}, "gzip", gunzip }, | |
49 | { {0x42, 0x5a}, "bzip2", bunzip2 }, | |
50 | { {0x5d, 0x00}, "lzma", unlzma }, | |
51 | { {0xfd, 0x37}, "xz", unxz }, | |
52 | { {0x89, 0x4c}, "lzo", unlzo }, | |
53 | { {0x02, 0x21}, "lz4", unlz4 }, | |
54 | { {0, 0}, NULL, NULL } | |
55 | }; | |
56 | ||
57 | decompress_fn __init decompress_method(const unsigned char *inbuf, long len, | |
58 | const char **name) | |
59 | { | |
60 | const struct compress_format *cf; | |
61 | ||
62 | if (len < 2) | |
63 | return NULL; /* Need at least this much... */ | |
64 | ||
65 | pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]); | |
66 | ||
67 | for (cf = compressed_formats; cf->name; cf++) { | |
68 | if (!memcmp(inbuf, cf->magic, 2)) | |
69 | break; | |
70 | ||
71 | } | |
72 | if (name) | |
73 | *name = cf->name; | |
74 | return cf->decompressor; | |
75 | } |