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