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 { {037, 0213}, "gzip", gunzip },
48 { {037, 0236}, "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
decompress_method(const unsigned char * inbuf,long len,const char ** name)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 }
76