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