| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* |
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| 3 | * decompress.c |
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| 4 | * |
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| 5 | * Detect the decompression method based on magic number |
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| 6 | */ |
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| 7 | |
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| 8 | #include <linux/decompress/generic.h> |
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| 9 | |
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| 10 | #include <linux/decompress/bunzip2.h> |
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| 11 | #include <linux/decompress/unlzma.h> |
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| 12 | #include <linux/decompress/unxz.h> |
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| 13 | #include <linux/decompress/inflate.h> |
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| 14 | #include <linux/decompress/unlzo.h> |
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| 15 | #include <linux/decompress/unlz4.h> |
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| 16 | #include <linux/decompress/unzstd.h> |
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| 17 | |
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| 18 | #include <linux/types.h> |
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| 19 | #include <linux/string.h> |
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| 20 | #include <linux/init.h> |
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| 21 | #include <linux/printk.h> |
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| 22 | |
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| 23 | #ifndef CONFIG_DECOMPRESS_GZIP |
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| 24 | # define gunzip NULL |
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| 25 | #endif |
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| 26 | #ifndef CONFIG_DECOMPRESS_BZIP2 |
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| 27 | # define bunzip2 NULL |
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| 28 | #endif |
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| 29 | #ifndef CONFIG_DECOMPRESS_LZMA |
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| 30 | # define unlzma NULL |
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| 31 | #endif |
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| 32 | #ifndef CONFIG_DECOMPRESS_XZ |
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| 33 | # define unxz NULL |
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| 34 | #endif |
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| 35 | #ifndef CONFIG_DECOMPRESS_LZO |
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| 36 | # define unlzo NULL |
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| 37 | #endif |
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| 38 | #ifndef CONFIG_DECOMPRESS_LZ4 |
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| 39 | # define unlz4 NULL |
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| 40 | #endif |
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| 41 | #ifndef CONFIG_DECOMPRESS_ZSTD |
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| 42 | # define unzstd NULL |
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| 43 | #endif |
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| 44 | |
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| 45 | struct compress_format { |
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| 46 | unsigned char magic[2]; |
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| 47 | const char *name; |
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| 48 | decompress_fn decompressor; |
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| 49 | }; |
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| 50 | |
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| 51 | static const struct compress_format compressed_formats[] __initconst = { |
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| 52 | { {0x1f, 0x8b}, "gzip" , gunzip }, |
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| 53 | { {0x1f, 0x9e}, "gzip" , gunzip }, |
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| 54 | { {0x42, 0x5a}, "bzip2" , bunzip2 }, |
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| 55 | { {0x5d, 0x00}, "lzma" , unlzma }, |
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| 56 | { {0xfd, 0x37}, "xz" , unxz }, |
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| 57 | { {0x89, 0x4c}, "lzo" , unlzo }, |
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| 58 | { {0x02, 0x21}, "lz4" , unlz4 }, |
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| 59 | { {0x28, 0xb5}, "zstd" , unzstd }, |
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| 60 | { {0, 0}, NULL, NULL } |
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| 61 | }; |
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| 62 | |
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| 63 | decompress_fn __init decompress_method(const unsigned char *inbuf, long len, |
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| 64 | const char **name) |
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| 65 | { |
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| 66 | const struct compress_format *cf; |
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| 67 | |
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| 68 | if (len < 2) { |
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| 69 | if (name) |
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| 70 | *name = NULL; |
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| 71 | return NULL; /* Need at least this much... */ |
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| 72 | } |
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| 73 | |
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| 74 | pr_debug("Compressed data magic: %#.2x %#.2x\n" , inbuf[0], inbuf[1]); |
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| 75 | |
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| 76 | for (cf = compressed_formats; cf->name; cf++) { |
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| 77 | if (!memcmp(p: inbuf, q: cf->magic, size: 2)) |
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| 78 | break; |
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| 79 | |
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| 80 | } |
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| 81 | if (name) |
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| 82 | *name = cf->name; |
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| 83 | return cf->decompressor; |
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| 84 | } |
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| 85 | |
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