/*
   * decompress.c
   *
   * Detect the decompression method based on magic number
   */
  
  #include <linux/decompress/generic.h>
  
  #include <linux/decompress/bunzip2.h>
  #include <linux/decompress/unlzma.h>

  #include <linux/decompress/unxz.h>

  #include <linux/decompress/inflate.h>

  #include <linux/decompress/unlzo.h>

  
  #include <linux/types.h>
  #include <linux/string.h>

  #ifndef CONFIG_DECOMPRESS_GZIP
  # define gunzip NULL
  #endif
  #ifndef CONFIG_DECOMPRESS_BZIP2
  # define bunzip2 NULL
  #endif
  #ifndef CONFIG_DECOMPRESS_LZMA
  # define unlzma NULL
  #endif

  #ifndef CONFIG_DECOMPRESS_XZ
  # define unxz NULL
  #endif

  #ifndef CONFIG_DECOMPRESS_LZO
  # define unlzo NULL
  #endif

  static const struct compress_format {
  	unsigned char magic[2];
  	const char *name;
  	decompress_fn decompressor;
  } compressed_formats[] = {

  	{ {037, 0213}, "gzip", gunzip },
  	{ {037, 0236}, "gzip", gunzip },

  	{ {0x42, 0x5a}, "bzip2", bunzip2 },

  	{ {0x5d, 0x00}, "lzma", unlzma },

  	{ {0xfd, 0x37}, "xz", unxz },

  	{ {0x89, 0x4c}, "lzo", unlzo },

  	{ {0, 0}, NULL, NULL }
  };
  
  decompress_fn decompress_method(const unsigned char *inbuf, int len,
  				const char **name)
  {
  	const struct compress_format *cf;
  
  	if (len < 2)
  		return NULL;	/* Need at least this much... */

  	for (cf = compressed_formats; cf->name; cf++) {

  		if (!memcmp(inbuf, cf->magic, 2))
  			break;
  
  	}
  	if (name)
  		*name = cf->name;
  	return cf->decompressor;
  }