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