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 #include <linux/printk.h> 20 21 #ifndef CONFIG_DECOMPRESS_GZIP 22 # define gunzip NULL 23 #endif 24 #ifndef CONFIG_DECOMPRESS_BZIP2 25 # define bunzip2 NULL 26 #endif 27 #ifndef CONFIG_DECOMPRESS_LZMA 28 # define unlzma NULL 29 #endif 30 #ifndef CONFIG_DECOMPRESS_XZ 31 # define unxz NULL 32 #endif 33 #ifndef CONFIG_DECOMPRESS_LZO 34 # define unlzo NULL 35 #endif 36 #ifndef CONFIG_DECOMPRESS_LZ4 37 # define unlz4 NULL 38 #endif 39 40 struct compress_format { 41 unsigned char magic[2]; 42 const char *name; 43 decompress_fn decompressor; 44 }; 45 46 static const struct compress_format compressed_formats[] __initconst = { 47 { {0x1f, 0x8b}, "gzip", gunzip }, 48 { {0x1f, 0x9e}, "gzip", gunzip }, 49 { {0x42, 0x5a}, "bzip2", bunzip2 }, 50 { {0x5d, 0x00}, "lzma", unlzma }, 51 { {0xfd, 0x37}, "xz", unxz }, 52 { {0x89, 0x4c}, "lzo", unlzo }, 53 { {0x02, 0x21}, "lz4", unlz4 }, 54 { {0, 0}, NULL, NULL } 55 }; 56 57 decompress_fn __init decompress_method(const unsigned char *inbuf, long len, 58 const char **name) 59 { 60 const struct compress_format *cf; 61 62 if (len < 2) { 63 if (name) 64 *name = NULL; 65 return NULL; /* Need at least this much... */ 66 } 67 68 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]); 69 70 for (cf = compressed_formats; cf->name; cf++) { 71 if (!memcmp(inbuf, cf->magic, 2)) 72 break; 73 74 } 75 if (name) 76 *name = cf->name; 77 return cf->decompressor; 78 } 79