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1// SPDX-License-Identifier: GPL-2.02/*3 * decompress.c4 *5 * Detect the decompression method based on magic number6 */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_GZIP24# define gunzip NULL25#endif26#ifndef CONFIG_DECOMPRESS_BZIP227# define bunzip2 NULL28#endif29#ifndef CONFIG_DECOMPRESS_LZMA30# define unlzma NULL31#endif32#ifndef CONFIG_DECOMPRESS_XZ33# define unxz NULL34#endif35#ifndef CONFIG_DECOMPRESS_LZO36# define unlzo NULL37#endif38#ifndef CONFIG_DECOMPRESS_LZ439# define unlz4 NULL40#endif41#ifndef CONFIG_DECOMPRESS_ZSTD42# define unzstd NULL43#endif44 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}85