linux/lib/decompress.c
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   1/*
   2 * decompress.c
   3 *
   4 * Detect the decompression method based on magic number
   5 */
   6
   7#include <linux/decompress/generic.h>
   8
   9#include <linux/decompress/bunzip2.h>
  10#include <linux/decompress/unlzma.h>
  11#include <linux/decompress/unxz.h>
  12#include <linux/decompress/inflate.h>
  13#include <linux/decompress/unlzo.h>
  14
  15#include <linux/types.h>
  16#include <linux/string.h>
  17#include <linux/init.h>
  18
  19#ifndef CONFIG_DECOMPRESS_GZIP
  20# define gunzip NULL
  21#endif
  22#ifndef CONFIG_DECOMPRESS_BZIP2
  23# define bunzip2 NULL
  24#endif
  25#ifndef CONFIG_DECOMPRESS_LZMA
  26# define unlzma NULL
  27#endif
  28#ifndef CONFIG_DECOMPRESS_XZ
  29# define unxz NULL
  30#endif
  31#ifndef CONFIG_DECOMPRESS_LZO
  32# define unlzo NULL
  33#endif
  34
  35struct compress_format {
  36        unsigned char magic[2];
  37        const char *name;
  38        decompress_fn decompressor;
  39};
  40
  41static const struct compress_format compressed_formats[] __initdata = {
  42        { {037, 0213}, "gzip", gunzip },
  43        { {037, 0236}, "gzip", gunzip },
  44        { {0x42, 0x5a}, "bzip2", bunzip2 },
  45        { {0x5d, 0x00}, "lzma", unlzma },
  46        { {0xfd, 0x37}, "xz", unxz },
  47        { {0x89, 0x4c}, "lzo", unlzo },
  48        { {0, 0}, NULL, NULL }
  49};
  50
  51decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
  52                                const char **name)
  53{
  54        const struct compress_format *cf;
  55
  56        if (len < 2)
  57                return NULL;    /* Need at least this much... */
  58
  59        for (cf = compressed_formats; cf->name; cf++) {
  60                if (!memcmp(inbuf, cf->magic, 2))
  61                        break;
  62
  63        }
  64        if (name)
  65                *name = cf->name;
  66        return cf->decompressor;
  67}
  68
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