| 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 | } |