1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * decompress.c 4 * 5 * Detect the decompression method based on magic number 6 */ 7 8 #include <linux/decompress/generic.h> 9 10 #include <linux/decompress/bunzip2.h> 11 #include <linux/decompress/unlzma.h> 12 #include <linux/decompress/unxz.h> 13 #include <linux/decompress/inflate.h> 14 #include <linux/decompress/unlzo.h> 15 #include <linux/decompress/unlz4.h> 16 17 #include <linux/types.h> 18 #include <linux/string.h> 19 #include <linux/init.h> 20 #include <linux/printk.h> 21 22 #ifndef CONFIG_DECOMPRESS_GZIP 23 # define gunzip NULL 24 #endif 25 #ifndef CONFIG_DECOMPRESS_BZIP2 26 # define bunzip2 NULL 27 #endif 28 #ifndef CONFIG_DECOMPRESS_LZMA 29 # define unlzma NULL 30 #endif 31 #ifndef CONFIG_DECOMPRESS_XZ 32 # define unxz NULL 33 #endif 34 #ifndef CONFIG_DECOMPRESS_LZO 35 # define unlzo NULL 36 #endif 37 #ifndef CONFIG_DECOMPRESS_LZ4 38 # define unlz4 NULL 39 #endif 40 41 struct compress_format { 42 unsigned char magic[2]; 43 const char *name; 44 decompress_fn decompressor; 45 }; 46 47 static const struct compress_format compressed_formats[] __initconst = { 48 { {0x1f, 0x8b}, "gzip", gunzip }, 49 { {0x1f, 0x9e}, "gzip", gunzip }, 50 { {0x42, 0x5a}, "bzip2", bunzip2 }, 51 { {0x5d, 0x00}, "lzma", unlzma }, 52 { {0xfd, 0x37}, "xz", unxz }, 53 { {0x89, 0x4c}, "lzo", unlzo }, 54 { {0x02, 0x21}, "lz4", unlz4 }, 55 { {0, 0}, NULL, NULL } 56 }; 57 58 decompress_fn __init decompress_method(const unsigned char *inbuf, long len, 59 const char **name) 60 { 61 const struct compress_format *cf; 62 63 if (len < 2) { 64 if (name) 65 *name = NULL; 66 return NULL; /* Need at least this much... */ 67 } 68 69 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]); 70 71 for (cf = compressed_formats; cf->name; cf++) { 72 if (!memcmp(inbuf, cf->magic, 2)) 73 break; 74 75 } 76 if (name) 77 *name = cf->name; 78 return cf->decompressor; 79 } 80