1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * decompress.c
4 *
5 * Detect the decompression method based on magic number
6 */
7
8 #include <linux/decompress/generic.h>
9
10 #include <linux/decompress/bunzip2.h>
11 #include <linux/decompress/unlzma.h>
12 #include <linux/decompress/unxz.h>
13 #include <linux/decompress/inflate.h>
14 #include <linux/decompress/unlzo.h>
15 #include <linux/decompress/unlz4.h>
16
17 #include <linux/types.h>
18 #include <linux/string.h>
19 #include <linux/init.h>
20 #include <linux/printk.h>
21
22 #ifndef CONFIG_DECOMPRESS_GZIP
23 # define gunzip NULL
24 #endif
25 #ifndef CONFIG_DECOMPRESS_BZIP2
26 # define bunzip2 NULL
27 #endif
28 #ifndef CONFIG_DECOMPRESS_LZMA
29 # define unlzma NULL
30 #endif
31 #ifndef CONFIG_DECOMPRESS_XZ
32 # define unxz NULL
33 #endif
34 #ifndef CONFIG_DECOMPRESS_LZO
35 # define unlzo NULL
36 #endif
37 #ifndef CONFIG_DECOMPRESS_LZ4
38 # define unlz4 NULL
39 #endif
40
41 struct compress_format {
42 unsigned char magic[2];
43 const char *name;
44 decompress_fn decompressor;
45 };
46
47 static const struct compress_format compressed_formats[] __initconst = {
48 { {0x1f, 0x8b}, "gzip", gunzip },
49 { {0x1f, 0x9e}, "gzip", gunzip },
50 { {0x42, 0x5a}, "bzip2", bunzip2 },
51 { {0x5d, 0x00}, "lzma", unlzma },
52 { {0xfd, 0x37}, "xz", unxz },
53 { {0x89, 0x4c}, "lzo", unlzo },
54 { {0x02, 0x21}, "lz4", unlz4 },
55 { {0, 0}, NULL, NULL }
56 };
57
decompress_method(const unsigned char * inbuf,long len,const char ** name)58 decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
59 const char **name)
60 {
61 const struct compress_format *cf;
62
63 if (len < 2) {
64 if (name)
65 *name = NULL;
66 return NULL; /* Need at least this much... */
67 }
68
69 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
70
71 for (cf = compressed_formats; cf->name; cf++) {
72 if (!memcmp(inbuf, cf->magic, 2))
73 break;
74
75 }
76 if (name)
77 *name = cf->name;
78 return cf->decompressor;
79 }
80