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#include <linux/decompress/unlz4.h> 15 16#include <linux/types.h> 17#include <linux/string.h> 18#include <linux/init.h> 19#include <linux/printk.h> 20 21#ifndef CONFIG_DECOMPRESS_GZIP 22# define gunzip NULL 23#endif 24#ifndef CONFIG_DECOMPRESS_BZIP2 25# define bunzip2 NULL 26#endif 27#ifndef CONFIG_DECOMPRESS_LZMA 28# define unlzma NULL 29#endif 30#ifndef CONFIG_DECOMPRESS_XZ 31# define unxz NULL 32#endif 33#ifndef CONFIG_DECOMPRESS_LZO 34# define unlzo NULL 35#endif 36#ifndef CONFIG_DECOMPRESS_LZ4 37# define unlz4 NULL 38#endif 39 40struct compress_format { 41 unsigned char magic[2]; 42 const char *name; 43 decompress_fn decompressor; 44}; 45 46static const struct compress_format compressed_formats[] __initconst = { 47 { {0x1f, 0x8b}, "gzip", gunzip }, 48 { {0x1f, 0x9e}, "gzip", gunzip }, 49 { {0x42, 0x5a}, "bzip2", bunzip2 }, 50 { {0x5d, 0x00}, "lzma", unlzma }, 51 { {0xfd, 0x37}, "xz", unxz }, 52 { {0x89, 0x4c}, "lzo", unlzo }, 53 { {0x02, 0x21}, "lz4", unlz4 }, 54 { {0, 0}, NULL, NULL } 55}; 56 57decompress_fn __init decompress_method(const unsigned char *inbuf, long len, 58 const char **name) 59{ 60 const struct compress_format *cf; 61 62 if (len < 2) 63 return NULL; /* Need at least this much... */ 64 65 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]); 66 67 for (cf = compressed_formats; cf->name; cf++) { 68 if (!memcmp(inbuf, cf->magic, 2)) 69 break; 70 71 } 72 if (name) 73 *name = cf->name; 74 return cf->decompressor; 75} 76