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