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 20 #ifndef CONFIG_DECOMPRESS_GZIP 21 # define gunzip NULL 22 #endif 23 #ifndef CONFIG_DECOMPRESS_BZIP2 24 # define bunzip2 NULL 25 #endif 26 #ifndef CONFIG_DECOMPRESS_LZMA 27 # define unlzma NULL 28 #endif 29 #ifndef CONFIG_DECOMPRESS_XZ 30 # define unxz NULL 31 #endif 32 #ifndef CONFIG_DECOMPRESS_LZO 33 # define unlzo NULL 34 #endif 35 #ifndef CONFIG_DECOMPRESS_LZ4 36 # define unlz4 NULL 37 #endif 38 39 struct compress_format { 40 unsigned char magic[2]; 41 const char *name; 42 decompress_fn decompressor; 43 }; 44 45 static const struct compress_format compressed_formats[] __initconst = { 46 { {037, 0213}, "gzip", gunzip }, 47 { {037, 0236}, "gzip", gunzip }, 48 { {0x42, 0x5a}, "bzip2", bunzip2 }, 49 { {0x5d, 0x00}, "lzma", unlzma }, 50 { {0xfd, 0x37}, "xz", unxz }, 51 { {0x89, 0x4c}, "lzo", unlzo }, 52 { {0x02, 0x21}, "lz4", unlz4 }, 53 { {0, 0}, NULL, NULL } 54 }; 55 56 decompress_fn __init decompress_method(const unsigned char *inbuf, int len, 57 const char **name) 58 { 59 const struct compress_format *cf; 60 61 if (len < 2) 62 return NULL; /* Need at least this much... */ 63 64 for (cf = compressed_formats; cf->name; cf++) { 65 if (!memcmp(inbuf, cf->magic, 2)) 66 break; 67 68 } 69 if (name) 70 *name = cf->name; 71 return cf->decompressor; 72 } 73