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