LXR linux/lib/decompress.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * decompress.c
   4 *
   5 * Detect the decompression method based on magic number
   6 */
   7
   8#include <linux/decompress/generic.h>
   9
  10#include <linux/decompress/bunzip2.h>
  11#include <linux/decompress/unlzma.h>
  12#include <linux/decompress/unxz.h>
  13#include <linux/decompress/inflate.h>
  14#include <linux/decompress/unlzo.h>
  15#include <linux/decompress/unlz4.h>
  16
  17#include <linux/types.h>
  18#include <linux/string.h>
  19#include <linux/init.h>
  20#include <linux/printk.h>
  21
  22#ifndef CONFIG_DECOMPRESS_GZIP
  23# define gunzip NULL
  24#endif
  25#ifndef CONFIG_DECOMPRESS_BZIP2
  26# define bunzip2 NULL
  27#endif
  28#ifndef CONFIG_DECOMPRESS_LZMA
  29# define unlzma NULL
  30#endif
  31#ifndef CONFIG_DECOMPRESS_XZ
  32# define unxz NULL
  33#endif
  34#ifndef CONFIG_DECOMPRESS_LZO
  35# define unlzo NULL
  36#endif
  37#ifndef CONFIG_DECOMPRESS_LZ4
  38# define unlz4 NULL
  39#endif
  40
  41struct compress_format {
  42        unsigned char magic[2];
  43        const char *name;
  44        decompress_fn decompressor;
  45};
  46
  47static const struct compress_format compressed_formats[] __initconst = {
  48        { {0x1f, 0x8b}, "gzip", gunzip },
  49        { {0x1f, 0x9e}, "gzip", gunzip },
  50        { {0x42, 0x5a}, "bzip2", bunzip2 },
  51        { {0x5d, 0x00}, "lzma", unlzma },
  52        { {0xfd, 0x37}, "xz", unxz },
  53        { {0x89, 0x4c}, "lzo", unlzo },
  54        { {0x02, 0x21}, "lz4", unlz4 },
  55        { {0, 0}, NULL, NULL }
  56};
  57
  58decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
  59                                const char **name)
  60{
  61        const struct compress_format *cf;
  62
  63        if (len < 2) {
  64                if (name)
  65                        *name = NULL;
  66                return NULL;    /* Need at least this much... */
  67        }
  68
  69        pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
  70
  71        for (cf = compressed_formats; cf->name; cf++) {
  72                if (!memcmp(inbuf, cf->magic, 2))
  73                        break;
  74
  75        }
  76        if (name)
  77                *name = cf->name;
  78        return cf->decompressor;
  79}
  80