Externals: Add libLZMA.

Externals/liblzma/simple/simple_decoder.c

@@ -0,0 +1,40 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       simple_decoder.c
+/// \brief      Properties decoder for simple filters
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "simple_decoder.h"
+
+
+extern lzma_ret
+lzma_simple_props_decode(void **options, const lzma_allocator *allocator,
+		const uint8_t *props, size_t props_size)
+{
+	if (props_size == 0)
+		return LZMA_OK;
+
+	if (props_size != 4)
+		return LZMA_OPTIONS_ERROR;
+
+	lzma_options_bcj *opt = lzma_alloc(
+			sizeof(lzma_options_bcj), allocator);
+	if (opt == NULL)
+		return LZMA_MEM_ERROR;
+
+	opt->start_offset = unaligned_read32le(props);
+
+	// Don't leave an options structure allocated if start_offset is zero.
+	if (opt->start_offset == 0)
+		lzma_free(opt, allocator);
+	else
+		*options = opt;
+
+	return LZMA_OK;
+}