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