// 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/decompress/unzstd.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#ifndef CONFIG_DECOMPRESS_ZSTD# define unzstd NULL#endif struct compress_format {	unsigned char magic[2];	const char *name;	decompress_fn decompressor;}; static const struct compress_format compressed_formats[] __initconst = {	{ .magic = {0x1f, 0x8b}, .name = "gzip", .decompressor = gunzip },	{ .magic = {0x1f, 0x9e}, .name = "gzip", .decompressor = gunzip },	{ .magic = {0x42, 0x5a}, .name = "bzip2", .decompressor = bunzip2 },	{ .magic = {0x5d, 0x00}, .name = "lzma", .decompressor = unlzma },	{ .magic = {0xfd, 0x37}, .name = "xz", .decompressor = unxz },	{ .magic = {0x89, 0x4c}, .name = "lzo", .decompressor = unlzo },	{ .magic = {0x02, 0x21}, .name = "lz4", .decompressor = unlz4 },	{ .magic = {0x28, 0xb5}, .name = "zstd", .decompressor = unzstd },	{ /* sentinel */ }}; 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;}