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