merklecheckoutputstream.h

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/*
 * Copyright (C) 2001-2006 Jacek Sieka, arnetheduck on gmail point com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#if !defined(MERKLE_CHECK_OUTPUT_STREAM_H)
#define MERKLE_CHECK_OUTPUT_STREAM_H

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include "Streams.h"
#include "MerkleTree.h"

template<class TreeType, bool managed>
class MerkleCheckOutputStream : public OutputStream {
public:
	MerkleCheckOutputStream(const TreeType& aTree, OutputStream* aStream, int64_t start) : s(aStream), real(aTree), cur(aTree.getBlockSize()), verified(0), bufPos(0) {
		// Only start at block boundaries
		dcassert(start % aTree.getBlockSize() == 0);
		cur.setFileSize(start);

		size_t nBlocks = static_cast<size_t>(start / aTree.getBlockSize());
		if(nBlocks > aTree.getLeaves().size()) {
			dcdebug("Invalid tree / parameters");
			return;
		}
		cur.getLeaves().insert(cur.getLeaves().begin(), aTree.getLeaves().begin(), aTree.getLeaves().begin() + nBlocks);
	}

	virtual ~MerkleCheckOutputStream() throw() { if(managed) delete s; }

	virtual size_t flush() throw(FileException) {
		if (bufPos != 0)
			cur.update(buf, bufPos);
		bufPos = 0;

		cur.finalize();
		if(cur.getLeaves().size() == real.getLeaves().size()) {
			if (cur.getRoot() != real.getRoot())
				throw FileException(STRING(TTH_INCONSISTENCY));
		} else {
			checkTrees();
		}
		return s->flush();
	}

	virtual size_t write(const void* b, size_t len) throw(FileException) {
		u_int8_t* xb = (u_int8_t*)b;
		size_t pos = 0;

		if(bufPos != 0) {
			size_t bytes = min(TreeType::BASE_BLOCK_SIZE - bufPos, len);
			memcpy(buf + bufPos, xb, bytes);
			pos = bytes;
			bufPos += bytes;

			if(bufPos == TreeType::BASE_BLOCK_SIZE) {
				cur.update(buf, TreeType::BASE_BLOCK_SIZE);
				bufPos = 0;
			}
		}

		if(pos < len) {
			dcassert(bufPos == 0);
			size_t left = len - pos;
			size_t part = left - (left %  TreeType::BASE_BLOCK_SIZE);
			if(part > 0) {
				cur.update(xb + pos, part);
				pos += part;
			}
			left = len - pos;
			memcpy(buf, xb + pos, left);
			bufPos = left;
		}

		checkTrees();
		return s->write(b, len);
	}

	int64_t verifiedBytes() {
		return min(real.getFileSize(), (int64_t)(cur.getBlockSize() * cur.getLeaves().size()));
	}
private:
	OutputStream* s;
	const TreeType& real;
	TreeType cur;
	size_t verified;

	u_int8_t buf[TreeType::BASE_BLOCK_SIZE];
	size_t bufPos;

	void checkTrees() throw(FileException) {
		while(cur.getLeaves().size() > verified) {
			if(cur.getLeaves().size() > real.getLeaves().size() ||
				!(cur.getLeaves()[verified] == real.getLeaves()[verified])) 
			{
				throw FileException(STRING(TTH_INCONSISTENCY));
			}
			verified++;
		}
	}
};

#endif // !defined(MERKLE_CHECK_OUTPUT_STREAM_H)