[linux-block.git] / lib / decompress.c

// SPDX-License-Identifier: GPL-2.0
/*
 * decompress.c
 *
 * Detect the decompression method based on magic number
 */

#include <linux/decompress/generic.h>

#include <linux/decompress/bunzip2.h>
#include <linux/decompress/unlzma.h>
#include <linux/decompress/unxz.h>
#include <linux/decompress/inflate.h>
#include <linux/decompress/unlzo.h>
#include <linux/decompress/unlz4.h>

#include <linux/types.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/printk.h>

#ifndef CONFIG_DECOMPRESS_GZIP
# define gunzip NULL
#endif
#ifndef CONFIG_DECOMPRESS_BZIP2
# define bunzip2 NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZMA
# define unlzma NULL
#endif
#ifndef CONFIG_DECOMPRESS_XZ
# define unxz NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZO
# define unlzo NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZ4
# define unlz4 NULL
#endif

struct compress_format {
	unsigned char magic[2];
	const char *name;
	decompress_fn decompressor;
};

static const struct compress_format compressed_formats[] __initconst = {
	{ {0x1f, 0x8b}, "gzip", gunzip },
	{ {0x1f, 0x9e}, "gzip", gunzip },
	{ {0x42, 0x5a}, "bzip2", bunzip2 },
	{ {0x5d, 0x00}, "lzma", unlzma },
	{ {0xfd, 0x37}, "xz", unxz },
	{ {0x89, 0x4c}, "lzo", unlzo },
	{ {0x02, 0x21}, "lz4", unlz4 },
	{ {0, 0}, NULL, NULL }
};

decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
				const char **name)
{
	const struct compress_format *cf;

	if (len < 2) {
		if (name)
			*name = NULL;
		return NULL;	/* Need at least this much... */
	}

	pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);

	for (cf = compressed_formats; cf->name; cf++) {
		if (!memcmp(inbuf, cf->magic, 2))
			break;

	}
	if (name)
		*name = cf->name;
	return cf->decompressor;
}
Commit	Line	Data
	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
	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	}