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/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#include <linux/printk.h>
  20
  21#ifndef CONFIG_DECOMPRESS_GZIP
  22# define gunzip NULL
  23#endif
  24#ifndef CONFIG_DECOMPRESS_BZIP2
  25# define bunzip2 NULL
  26#endif
  27#ifndef CONFIG_DECOMPRESS_LZMA
  28# define unlzma NULL
  29#endif
  30#ifndef CONFIG_DECOMPRESS_XZ
  31# define unxz NULL
  32#endif
  33#ifndef CONFIG_DECOMPRESS_LZO
  34# define unlzo NULL
  35#endif
  36#ifndef CONFIG_DECOMPRESS_LZ4
  37# define unlz4 NULL
  38#endif
  39
  40struct compress_format {
  41        unsigned char magic[2];
  42        const char *name;
  43        decompress_fn decompressor;
  44};
  45
  46static const struct compress_format compressed_formats[] __initconst = {
  47        { {0x1f, 0x8b}, "gzip", gunzip },
  48        { {0x1f, 0x9e}, "gzip", gunzip },
  49        { {0x42, 0x5a}, "bzip2", bunzip2 },
  50        { {0x5d, 0x00}, "lzma", unlzma },
  51        { {0xfd, 0x37}, "xz", unxz },
  52        { {0x89, 0x4c}, "lzo", unlzo },
  53        { {0x02, 0x21}, "lz4", unlz4 },
  54        { {0, 0}, NULL, NULL }
  55};
  56
  57decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
  58                                const char **name)
  59{
  60        const struct compress_format *cf;
  61
  62        if (len < 2) {
  63                if (name)
  64                        *name = NULL;
  65                return NULL;    /* Need at least this much... */
  66        }
  67
  68        pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
  69
  70        for (cf = compressed_formats; cf->name; cf++) {
  71                if (!memcmp(inbuf, cf->magic, 2))
  72                        break;
  73
  74        }
  75        if (name)
  76                *name = cf->name;
  77        return cf->decompressor;
  78}
  79