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 #include <linux/decompress/unzstd.h> 17 18 #include <linux/types.h> 19 #include <linux/string.h> 20 #include <linux/init.h> 21 #include <linux/printk.h> 22 23 #ifndef CONFIG_DECOMPRESS_GZIP 24 # define gunzip NULL 25 #endif 26 #ifndef CONFIG_DECOMPRESS_BZIP2 27 # define bunzip2 NULL 28 #endif 29 #ifndef CONFIG_DECOMPRESS_LZMA 30 # define unlzma NULL 31 #endif 32 #ifndef CONFIG_DECOMPRESS_XZ 33 # define unxz NULL 34 #endif 35 #ifndef CONFIG_DECOMPRESS_LZO 36 # define unlzo NULL 37 #endif 38 #ifndef CONFIG_DECOMPRESS_LZ4 39 # define unlz4 NULL 40 #endif 41 #ifndef CONFIG_DECOMPRESS_ZSTD 42 # define unzstd NULL 43 #endif 44 45 struct compress_format { 46 unsigned char magic[2]; 47 const char *name; 48 decompress_fn decompressor; 49 }; 50 51 static const struct compress_format compressed_formats[] __initconst = { 52 { {0x1f, 0x8b}, "gzip", gunzip }, 53 { {0x1f, 0x9e}, "gzip", gunzip }, 54 { {0x42, 0x5a}, "bzip2", bunzip2 }, 55 { {0x5d, 0x00}, "lzma", unlzma }, 56 { {0xfd, 0x37}, "xz", unxz }, 57 { {0x89, 0x4c}, "lzo", unlzo }, 58 { {0x02, 0x21}, "lz4", unlz4 }, 59 { {0x28, 0xb5}, "zstd", unzstd }, 60 { {0, 0}, NULL, NULL } 61 }; 62 63 decompress_fn __init decompress_method(const unsigned char *inbuf, long len, 64 const char **name) 65 { 66 const struct compress_format *cf; 67 68 if (len < 2) { 69 if (name) 70 *name = NULL; 71 return NULL; /* Need at least this much... */ 72 } 73 74 pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]); 75 76 for (cf = compressed_formats; cf->name; cf++) { 77 if (!memcmp(inbuf, cf->magic, 2)) 78 break; 79 80 } 81 if (name) 82 *name = cf->name; 83 return cf->decompressor; 84 } 85