1 files changed, 90 insertions, 0 deletions
diff --git a/src/liblzma/common/block_util.c b/src/liblzma/common/block_util.c
new file mode 100644
index 0000000..acb3111
--- /dev/null
+++ b/src/liblzma/common/block_util.c
@@ -0,0 +1,90 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       block_util.c
+/// \brief      Utility functions to handle lzma_block
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+#include "index.h"
+
+
+extern LZMA_API(lzma_ret)
+lzma_block_compressed_size(lzma_block *block, lzma_vli unpadded_size)
+{
+	// Validate everything but Uncompressed Size and filters.
+	if (lzma_block_unpadded_size(block) == 0)
+		return LZMA_PROG_ERROR;
+
+	const uint32_t container_size = block->header_size
+			+ lzma_check_size(block->check);
+
+	// Validate that Compressed Size will be greater than zero.
+	if (unpadded_size <= container_size)
+		return LZMA_DATA_ERROR;
+
+	// Calculate what Compressed Size is supposed to be.
+	// If Compressed Size was present in Block Header,
+	// compare that the new value matches it.
+	const lzma_vli compressed_size = unpadded_size - container_size;
+	if (block->compressed_size != LZMA_VLI_UNKNOWN
+			&& block->compressed_size != compressed_size)
+		return LZMA_DATA_ERROR;
+
+	block->compressed_size = compressed_size;
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_vli)
+lzma_block_unpadded_size(const lzma_block *block)
+{
+	// Validate the values that we are interested in i.e. all but
+	// Uncompressed Size and the filters.
+	//
+	// NOTE: This function is used for validation too, so it is
+	// essential that these checks are always done even if
+	// Compressed Size is unknown.
+	if (block == NULL || block->version > 1
+			|| block->header_size < LZMA_BLOCK_HEADER_SIZE_MIN
+			|| block->header_size > LZMA_BLOCK_HEADER_SIZE_MAX
+			|| (block->header_size & 3)
+			|| !lzma_vli_is_valid(block->compressed_size)
+			|| block->compressed_size == 0
+			|| (unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
+		return 0;
+
+	// If Compressed Size is unknown, return that we cannot know
+	// size of the Block either.
+	if (block->compressed_size == LZMA_VLI_UNKNOWN)
+		return LZMA_VLI_UNKNOWN;
+
+	// Calculate Unpadded Size and validate it.
+	const lzma_vli unpadded_size = block->compressed_size
+				+ block->header_size
+				+ lzma_check_size(block->check);
+
+	assert(unpadded_size >= UNPADDED_SIZE_MIN);
+	if (unpadded_size > UNPADDED_SIZE_MAX)
+		return 0;
+
+	return unpadded_size;
+}
+
+
+extern LZMA_API(lzma_vli)
+lzma_block_total_size(const lzma_block *block)
+{
+	lzma_vli unpadded_size = lzma_block_unpadded_size(block);
+
+	if (unpadded_size != LZMA_VLI_UNKNOWN)
+		unpadded_size = vli_ceil4(unpadded_size);
+
+	return unpadded_size;
+}