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/inflate.h> 12#include <linux/decompress/unlzo.h> 13 14#include <linux/types.h> 15#include <linux/string.h> 16 17#ifndef CONFIG_DECOMPRESS_GZIP 18# define gunzip NULL 19#endif 20#ifndef CONFIG_DECOMPRESS_BZIP2 21# define bunzip2 NULL 22#endif 23#ifndef CONFIG_DECOMPRESS_LZMA 24# define unlzma NULL 25#endif 26#ifndef CONFIG_DECOMPRESS_LZO 27# define unlzo NULL 28#endif 29 30static const struct compress_format { 31 unsigned char magic[2]; 32 const char *name; 33 decompress_fn decompressor; 34} compressed_formats[] = { 35 { {037, 0213}, "gzip", gunzip }, 36 { {037, 0236}, "gzip", gunzip }, 37 { {0x42, 0x5a}, "bzip2", bunzip2 }, 38 { {0x5d, 0x00}, "lzma", unlzma }, 39 { {0x89, 0x4c}, "lzo", unlzo }, 40 { {0, 0}, NULL, NULL } 41}; 42 43decompress_fn decompress_method(const unsigned char *inbuf, int len, 44 const char **name) 45{ 46 const struct compress_format *cf; 47 48 if (len < 2) 49 return NULL; /* Need at least this much... */ 50 51 for (cf = compressed_formats; cf->name; cf++) { 52 if (!memcmp(inbuf, cf->magic, 2)) 53 break; 54 55 } 56 if (name) 57 *name = cf->name; 58 return cf->decompressor; 59} 60