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 15 #include <linux/types.h> 16 #include <linux/string.h> 17 #include <linux/init.h> 18 19 #ifndef CONFIG_DECOMPRESS_GZIP 20 # define gunzip NULL 21 #endif 22 #ifndef CONFIG_DECOMPRESS_BZIP2 23 # define bunzip2 NULL 24 #endif 25 #ifndef CONFIG_DECOMPRESS_LZMA 26 # define unlzma NULL 27 #endif 28 #ifndef CONFIG_DECOMPRESS_XZ 29 # define unxz NULL 30 #endif 31 #ifndef CONFIG_DECOMPRESS_LZO 32 # define unlzo NULL 33 #endif 34 35 struct compress_format { 36 unsigned char magic[2]; 37 const char *name; 38 decompress_fn decompressor; 39 }; 40 41 static const struct compress_format compressed_formats[] __initconst = { 42 { {037, 0213}, "gzip", gunzip }, 43 { {037, 0236}, "gzip", gunzip }, 44 { {0x42, 0x5a}, "bzip2", bunzip2 }, 45 { {0x5d, 0x00}, "lzma", unlzma }, 46 { {0xfd, 0x37}, "xz", unxz }, 47 { {0x89, 0x4c}, "lzo", unlzo }, 48 { {0, 0}, NULL, NULL } 49 }; 50 51 decompress_fn __init decompress_method(const unsigned char *inbuf, int len, 52 const char **name) 53 { 54 const struct compress_format *cf; 55 56 if (len < 2) 57 return NULL; /* Need at least this much... */ 58 59 for (cf = compressed_formats; cf->name; cf++) { 60 if (!memcmp(inbuf, cf->magic, 2)) 61 break; 62 63 } 64 if (name) 65 *name = cf->name; 66 return cf->decompressor; 67 } 68