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 #include <linux/decompress/unzstd.h>
17
18 #include <linux/types.h>
19 #include <linux/string.h>
20 #include <linux/init.h>
21 #include <linux/printk.h>
22
23 #ifndef CONFIG_DECOMPRESS_GZIP
24 # define gunzip NULL
25 #endif
26 #ifndef CONFIG_DECOMPRESS_BZIP2
27 # define bunzip2 NULL
28 #endif
29 #ifndef CONFIG_DECOMPRESS_LZMA
30 # define unlzma NULL
31 #endif
32 #ifndef CONFIG_DECOMPRESS_XZ
33 # define unxz NULL
34 #endif
35 #ifndef CONFIG_DECOMPRESS_LZO
36 # define unlzo NULL
37 #endif
38 #ifndef CONFIG_DECOMPRESS_LZ4
39 # define unlz4 NULL
40 #endif
41 #ifndef CONFIG_DECOMPRESS_ZSTD
42 # define unzstd NULL
43 #endif
44
45 struct compress_format {
46 unsigned char magic[2];
47 const char *name;
48 decompress_fn decompressor;
49 };
50
51 static const struct compress_format compressed_formats[] __initconst = {
52 { {0x1f, 0x8b}, "gzip", gunzip },
53 { {0x1f, 0x9e}, "gzip", gunzip },
54 { {0x42, 0x5a}, "bzip2", bunzip2 },
55 { {0x5d, 0x00}, "lzma", unlzma },
56 { {0xfd, 0x37}, "xz", unxz },
57 { {0x89, 0x4c}, "lzo", unlzo },
58 { {0x02, 0x21}, "lz4", unlz4 },
59 { {0x28, 0xb5}, "zstd", unzstd },
60 { {0, 0}, NULL, NULL }
61 };
62
63 decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
64 const char **name)
65 {
66 const struct compress_format *cf;
67
68 if (len < 2) {
69 if (name)
70 *name = NULL;
71 return NULL; /* Need at least this much... */
72 }
73
74 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
75
76 for (cf = compressed_formats; cf->name; cf++) {
77 if (!memcmp(inbuf, cf->magic, 2))
78 break;
79
80 }
81 if (name)
82 *name = cf->name;
83 return cf->decompressor;
84 }
85
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