1 files changed, 211 insertions, 0 deletions
diff --git a/src/liblzma/common/block_header_encoder.c b/src/liblzma/common/block_header_encoder.c
new file mode 100644
index 00000000..594b4fc0
--- /dev/null
+++ b/src/liblzma/common/block_header_encoder.c
@@ -0,0 +1,211 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       block_header_encoder.c
+/// \brief      Encodes Block Header 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 "common.h"
+#include "check.h"
+
+
+extern LZMA_API lzma_ret
+lzma_block_header_size(lzma_options_block *options)
+{
+	// Block Flags take two bytes.
+	size_t size = 2;
+
+	// Compressed Size
+	if (!lzma_vli_is_valid(options->compressed_size)) {
+		return LZMA_PROG_ERROR;
+
+	} else if (options->compressed_reserve != 0) {
+		// Make sure that the known Compressed Size fits into the
+		// reserved space. Note that lzma_vli_size() will return zero
+		// if options->compressed_size is LZMA_VLI_VALUE_UNKNOWN, so
+		// we don't need to handle that special case separately.
+		if (options->compressed_reserve > LZMA_VLI_BYTES_MAX
+				|| lzma_vli_size(options->compressed_size)
+				> (size_t)(options->compressed_reserve))
+			return LZMA_PROG_ERROR;
+
+		size += options->compressed_reserve;
+
+	} else if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN) {
+		// Compressed Size is known. We have already checked
+		// that is is a valid VLI, and since it isn't
+		// LZMA_VLI_VALUE_UNKNOWN, we can be sure that
+		// lzma_vli_size() will succeed.
+		size += lzma_vli_size(options->compressed_size);
+	}
+
+	// Uncompressed Size
+	if (!lzma_vli_is_valid(options->uncompressed_size)) {
+		return LZMA_PROG_ERROR;
+
+	} else if (options->uncompressed_reserve != 0) {
+		if (options->uncompressed_reserve > LZMA_VLI_BYTES_MAX
+				|| lzma_vli_size(options->uncompressed_size)
+				> (size_t)(options->uncompressed_reserve))
+			return LZMA_PROG_ERROR;
+
+		size += options->uncompressed_reserve;
+
+	} else if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN) {
+		size += lzma_vli_size(options->uncompressed_size);
+	}
+
+	// List of Filter Flags
+	for (size_t i = 0; options->filters[i].id != LZMA_VLI_VALUE_UNKNOWN;
+			++i) {
+		// Don't allow too many filters.
+		if (i == 7)
+			return LZMA_PROG_ERROR;
+
+		uint32_t tmp;
+		const lzma_ret ret = lzma_filter_flags_size(&tmp,
+				options->filters + i);
+		if (ret != LZMA_OK)
+			return ret;
+
+		size += tmp;
+	}
+
+	// CRC32
+	if (options->has_crc32)
+		size += 4;
+
+	// Padding
+	int32_t padding;
+	if (options->padding == LZMA_BLOCK_HEADER_PADDING_AUTO) {
+		const uint32_t preferred = lzma_alignment_output(
+				options->filters, 1);
+		const uint32_t unaligned = size + options->alignment;
+		padding = (int32_t)(unaligned % preferred);
+		if (padding != 0)
+			padding = preferred - padding;
+	} else if (options->padding >= LZMA_BLOCK_HEADER_PADDING_MIN
+			&& options->padding <= LZMA_BLOCK_HEADER_PADDING_MAX) {
+		padding = options->padding;
+	} else {
+		return LZMA_PROG_ERROR;
+	}
+
+	// All success. Copy the calculated values to the options structure.
+	options->padding = padding;
+	options->header_size = size + (size_t)(padding);
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API lzma_ret
+lzma_block_header_encode(uint8_t *out, const lzma_options_block *options)
+{
+	// We write the Block Flags later.
+	if (options->header_size < 2)
+		return LZMA_PROG_ERROR;
+
+	const size_t out_size = options->header_size;
+	size_t out_pos = 2;
+
+	// Compressed Size
+	if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN
+			|| options->compressed_reserve != 0) {
+		const lzma_vli size = options->compressed_size
+					!= LZMA_VLI_VALUE_UNKNOWN
+				? options->compressed_size : 0;
+		size_t vli_pos = 0;
+		if (lzma_vli_encode(
+				size, &vli_pos, options->compressed_reserve,
+				out, &out_pos, out_size) != LZMA_STREAM_END)
+			return LZMA_PROG_ERROR;
+
+	}
+
+	// Uncompressed Size
+	if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN
+			|| options->uncompressed_reserve != 0) {
+		const lzma_vli size = options->uncompressed_size
+					!= LZMA_VLI_VALUE_UNKNOWN
+				? options->uncompressed_size : 0;
+		size_t vli_pos = 0;
+		if (lzma_vli_encode(
+				size, &vli_pos, options->uncompressed_reserve,
+				out, &out_pos, out_size) != LZMA_STREAM_END)
+			return LZMA_PROG_ERROR;
+
+	}
+
+	// Filter Flags
+	size_t filter_count;
+	for (filter_count = 0; options->filters[filter_count].id
+			!= LZMA_VLI_VALUE_UNKNOWN; ++filter_count) {
+		// There can be at maximum of seven filters.
+		if (filter_count == 7)
+			return LZMA_PROG_ERROR;
+
+		const lzma_ret ret = lzma_filter_flags_encode(out, &out_pos,
+				out_size, options->filters + filter_count);
+		// FIXME: Don't return LZMA_BUF_ERROR.
+		if (ret != LZMA_OK)
+			return ret;
+	}
+
+	// Block Flags 1
+	out[0] = filter_count;
+
+	if (options->has_eopm)
+		out[0] |= 0x08;
+	else if (options->uncompressed_size == LZMA_VLI_VALUE_UNKNOWN)
+		return LZMA_PROG_ERROR;
+
+	if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN
+			|| options->compressed_reserve != 0)
+		out[0] |= 0x10;
+
+	if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN
+			|| options->uncompressed_reserve != 0)
+		out[0] |= 0x20;
+
+	if (options->is_metadata)
+		out[0] |= 0x80;
+
+	// Block Flags 2
+	if (options->padding < LZMA_BLOCK_HEADER_PADDING_MIN
+			|| options->padding > LZMA_BLOCK_HEADER_PADDING_MAX)
+		return LZMA_PROG_ERROR;
+
+	out[1] = (uint8_t)(options->padding);
+
+	// CRC32
+	if (options->has_crc32) {
+		if (out_size - out_pos < 4)
+			return LZMA_PROG_ERROR;
+
+		const uint32_t crc = lzma_crc32(out, out_pos, 0);
+		for (size_t i = 0; i < 4; ++i)
+			out[out_pos++] = crc >> (i * 8);
+	}
+
+	// Padding - the amount of available space must now match with
+	// the size of the Padding field.
+	if (out_size - out_pos != (size_t)(options->padding))
+		return LZMA_PROG_ERROR;
+
+	memzero(out + out_pos, (size_t)(options->padding));
+
+	return LZMA_OK;
+}