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
45struct compress_format {
46	unsigned char magic[2];
47	const char *name;
48	decompress_fn decompressor;
49};
50
51static 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
63decompress_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}

 
 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
34static 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
48decompress_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}