Merge commit 'origin/master' into next

[linux-2.6-omap-h63xx.git] / lib / decompress.c

diff --git a/lib/decompress.c b/lib/decompress.c
new file mode 100644 (file)
index 0000000..d2842f5
--- /dev/null
+++ b/lib/decompress.c
@@ -0,0 +1,54 @@
+/*
+ * 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/inflate.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
+
+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 },
+       { {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;
+}