1 files changed, 75 insertions, 0 deletions
diff --git a/src/liblzma/common/stream_flags_encoder.c b/src/liblzma/common/stream_flags_encoder.c
new file mode 100644
index 00000000..55468580
--- /dev/null
+++ b/src/liblzma/common/stream_flags_encoder.c
@@ -0,0 +1,75 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       stream_flags_encoder.c
+/// \brief      Encodes Stream Header and Footer for .lzma files
+//
+//  Copyright (C) 2007 Lasse Collin
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2.1 of the License, or (at your option) any later version.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//  Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "stream_common.h"
+
+
+static bool
+stream_flags_encode(uint8_t *flags_byte, const lzma_stream_flags *options)
+{
+	// Check type
+	if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX)
+		return true;
+
+	*flags_byte = options->check;
+
+	// Usage of CRC32 in Block Headers
+	if (options->has_crc32)
+		*flags_byte |= 0x08;
+
+	// Single- or Multi-Block
+	if (options->is_multi)
+		*flags_byte |= 0x10;
+
+	return false;
+}
+
+
+extern LZMA_API lzma_ret
+lzma_stream_header_encode(uint8_t *out, const lzma_stream_flags *options)
+{
+	// Magic
+	memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
+
+	// Stream Flags
+	if (stream_flags_encode(out + sizeof(lzma_header_magic), options))
+		return LZMA_PROG_ERROR;;
+
+	// CRC32 of the Stream Header
+	const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic), 1, 0);
+
+	for (size_t i = 0; i < 4; ++i)
+		out[sizeof(lzma_header_magic) + 1 + i] = crc >> (i * 8);
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API lzma_ret
+lzma_stream_tail_encode(uint8_t *out, const lzma_stream_flags *options)
+{
+	// Stream Flags
+	if (stream_flags_encode(out, options))
+		return LZMA_PROG_ERROR;
+
+	// Magic
+	memcpy(out + 1, lzma_footer_magic, sizeof(lzma_footer_magic));
+
+	return LZMA_OK;
+}