LXR linux/lib/decompress.c

   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/inflate.h>
  12#include <linux/decompress/unlzo.h>
  13
  14#include <linux/types.h>
  15#include <linux/string.h>
  16
  17#ifndef CONFIG_DECOMPRESS_GZIP
  18# define gunzip NULL
  19#endif
  20#ifndef CONFIG_DECOMPRESS_BZIP2
  21# define bunzip2 NULL
  22#endif
  23#ifndef CONFIG_DECOMPRESS_LZMA
  24# define unlzma NULL
  25#endif
  26#ifndef CONFIG_DECOMPRESS_LZO
  27# define unlzo NULL
  28#endif
  29
  30static const struct compress_format {
  31        unsigned char magic[2];
  32        const char *name;
  33        decompress_fn decompressor;
  34} compressed_formats[] = {
  35        { {037, 0213}, "gzip", gunzip },
  36        { {037, 0236}, "gzip", gunzip },
  37        { {0x42, 0x5a}, "bzip2", bunzip2 },
  38        { {0x5d, 0x00}, "lzma", unlzma },
  39        { {0x89, 0x4c}, "lzo", unlzo },
  40        { {0, 0}, NULL, NULL }
  41};
  42
  43decompress_fn decompress_method(const unsigned char *inbuf, int len,
  44                                const char **name)
  45{
  46        const struct compress_format *cf;
  47
  48        if (len < 2)
  49                return NULL;    /* Need at least this much... */
  50
  51        for (cf = compressed_formats; cf->name; cf++) {
  52                if (!memcmp(inbuf, cf->magic, 2))
  53                        break;
  54
  55        }
  56        if (name)
  57                *name = cf->name;
  58        return cf->decompressor;
  59}
  60