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#include <linux/decompress/unlz4.h>
  15
  16#include <linux/types.h>
  17#include <linux/string.h>
  18#include <linux/init.h>
  19
  20#ifndef CONFIG_DECOMPRESS_GZIP
  21# define gunzip NULL
  22#endif
  23#ifndef CONFIG_DECOMPRESS_BZIP2
  24# define bunzip2 NULL
  25#endif
  26#ifndef CONFIG_DECOMPRESS_LZMA
  27# define unlzma NULL
  28#endif
  29#ifndef CONFIG_DECOMPRESS_XZ
  30# define unxz NULL
  31#endif
  32#ifndef CONFIG_DECOMPRESS_LZO
  33# define unlzo NULL
  34#endif
  35#ifndef CONFIG_DECOMPRESS_LZ4
  36# define unlz4 NULL
  37#endif
  38
  39struct compress_format {
  40        unsigned char magic[2];
  41        const char *name;
  42        decompress_fn decompressor;
  43};
  44
  45static const struct compress_format compressed_formats[] __initconst = {
  46        { {037, 0213}, "gzip", gunzip },
  47        { {037, 0236}, "gzip", gunzip },
  48        { {0x42, 0x5a}, "bzip2", bunzip2 },
  49        { {0x5d, 0x00}, "lzma", unlzma },
  50        { {0xfd, 0x37}, "xz", unxz },
  51        { {0x89, 0x4c}, "lzo", unlzo },
  52        { {0x02, 0x21}, "lz4", unlz4 },
  53        { {0, 0}, NULL, NULL }
  54};
  55
  56decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
  57                                const char **name)
  58{
  59        const struct compress_format *cf;
  60
  61        if (len < 2)
  62                return NULL;    /* Need at least this much... */
  63
  64        for (cf = compressed_formats; cf->name; cf++) {
  65                if (!memcmp(inbuf, cf->magic, 2))
  66                        break;
  67
  68        }
  69        if (name)
  70                *name = cf->name;
  71        return cf->decompressor;
  72}
  73
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