path: root/lib/decompress.c (plain)
blob: 62696dff5730be1927edfdafc7bc314e71226a88

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	if (name)
64	*name = NULL;
65	return NULL; /* Need at least this much... */
66	}
67
68	pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
69
70	for (cf = compressed_formats; cf->name; cf++) {
71	if (!memcmp(inbuf, cf->magic, 2))
72	break;
73
74	}
75	if (name)
76	*name = cf->name;
77	return cf->decompressor;
78	}
79