xref: /openbmc/linux/lib/decompress.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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 
30 static 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 
43 decompress_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