block index checking on load, extra redundant checks, misc refactoring

This commit is contained in:
Satoshi Nakamoto 2010-08-28 00:49:30 +00:00 committed by Gavin Andresen
parent 43deefa435
commit 7a37c906a1
5 changed files with 126 additions and 62 deletions

11
db.cpp
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@ -419,6 +419,9 @@ bool CTxDB::LoadBlockIndex()
// Watch for genesis block
if (pindexGenesisBlock == NULL && diskindex.GetBlockHash() == hashGenesisBlock)
pindexGenesisBlock = pindexNew;
if (!pindexNew->CheckIndex())
return error("LoadBlockIndex() : CheckIndex failed at %d", pindexNew->nHeight);
}
else
{
@ -454,7 +457,7 @@ bool CTxDB::LoadBlockIndex()
pindexBest = mapBlockIndex[hashBestChain];
nBestHeight = pindexBest->nHeight;
bnBestChainWork = pindexBest->bnChainWork;
printf("LoadBlockIndex(): hashBestChain=%s height=%d\n", hashBestChain.ToString().substr(0,16).c_str(), nBestHeight);
printf("LoadBlockIndex(): hashBestChain=%s height=%d\n", hashBestChain.ToString().substr(0,20).c_str(), nBestHeight);
// Load bnBestInvalidWork, OK if it doesn't exist
ReadBestInvalidWork(bnBestInvalidWork);
@ -463,6 +466,8 @@ bool CTxDB::LoadBlockIndex()
CBlockIndex* pindexFork = NULL;
for (CBlockIndex* pindex = pindexBest; pindex && pindex->pprev; pindex = pindex->pprev)
{
if (pindex->nHeight < 74000 && !mapArgs.count("-checkblocks"))
break;
CBlock block;
if (!block.ReadFromDisk(pindex))
return error("LoadBlockIndex() : block.ReadFromDisk failed");
@ -629,8 +634,8 @@ bool CWalletDB::LoadWallet()
//printf("LoadWallet %s\n", wtx.GetHash().ToString().c_str());
//printf(" %12I64d %s %s %s\n",
// wtx.vout[0].nValue,
// DateTimeStrFormat("%x %H:%M:%S", wtx.nTime).c_str(),
// wtx.hashBlock.ToString().substr(0,16).c_str(),
// DateTimeStrFormat("%x %H:%M:%S", wtx.GetBlockTime()).c_str(),
// wtx.hashBlock.ToString().substr(0,20).c_str(),
// wtx.mapValue["message"].c_str());
}
else if (strType == "key" || strType == "wkey")

View File

@ -500,8 +500,8 @@ bool CTransaction::AcceptTransaction(CTxDB& txdb, bool fCheckInputs, bool* pfMis
return error("AcceptTransaction() : CheckTransaction failed");
// To help v0.1.5 clients who would see it as a negative number
if (nLockTime > INT_MAX)
return error("AcceptTransaction() : not accepting nLockTime beyond 2038");
if ((int64)nLockTime > INT_MAX)
return error("AcceptTransaction() : not accepting nLockTime beyond 2038 yet");
// Do we already have it?
uint256 hash = GetHash();
@ -519,6 +519,9 @@ bool CTransaction::AcceptTransaction(CTxDB& txdb, bool fCheckInputs, bool* pfMis
COutPoint outpoint = vin[i].prevout;
if (mapNextTx.count(outpoint))
{
// Disable replacement feature for now
return false;
// Allow replacing with a newer version of the same transaction
if (i != 0)
return false;
@ -550,8 +553,8 @@ bool CTransaction::AcceptTransaction(CTxDB& txdb, bool fCheckInputs, bool* pfMis
{
if (ptxOld)
{
printf("mapTransaction.erase(%s) replacing with new version\n", ptxOld->GetHash().ToString().c_str());
mapTransactions.erase(ptxOld->GetHash());
printf("AcceptTransaction() : replacing tx %s with new version\n", ptxOld->GetHash().ToString().c_str());
ptxOld->RemoveFromMemoryPool();
}
AddToMemoryPool();
}
@ -748,6 +751,12 @@ void ResendWalletTransactions()
if (fFirst)
return;
// Only do it if there's been a new block since last time
static int64 nLastTime;
if (nTimeBestReceived < nLastTime)
return;
nLastTime = GetTime();
// Rebroadcast any of our txes that aren't in a block yet
printf("ResendWalletTransactions()\n");
CTxDB txdb("r");
@ -785,9 +794,13 @@ void ResendWalletTransactions()
// CBlock and CBlockIndex
//
bool CBlock::ReadFromDisk(const CBlockIndex* pblockindex, bool fReadTransactions)
bool CBlock::ReadFromDisk(const CBlockIndex* pindex, bool fReadTransactions)
{
return ReadFromDisk(pblockindex->nFile, pblockindex->nBlockPos, fReadTransactions);
if (!ReadFromDisk(pindex->nFile, pindex->nBlockPos, fReadTransactions))
return false;
if (GetHash() != pindex->GetBlockHash())
return error("CBlock::ReadFromDisk() : GetHash() doesn't match index");
return true;
}
uint256 GetOrphanRoot(const CBlock* pblock)
@ -829,7 +842,7 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast)
assert(pindexFirst);
// Limit adjustment step
int64 nActualTimespan = (int64)pindexLast->nTime - (int64)pindexFirst->nTime;
int64 nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
printf(" nActualTimespan = %"PRI64d" before bounds\n", nActualTimespan);
if (nActualTimespan < nTargetTimespan/4)
nActualTimespan = nTargetTimespan/4;
@ -854,6 +867,22 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast)
return bnNew.GetCompact();
}
bool CheckProofOfWork(uint256 hash, unsigned int nBits)
{
CBigNum bnTarget;
bnTarget.SetCompact(nBits);
// Check range
if (bnTarget <= 0 || bnTarget > bnProofOfWorkLimit)
return error("CheckProofOfWork() : nBits below minimum work");
// Check proof of work matches claimed amount
if (hash > bnTarget.getuint256())
return error("CheckProofOfWork() : hash doesn't match nBits");
return true;
}
bool IsInitialBlockDownload()
{
if (pindexBest == NULL)
@ -866,7 +895,7 @@ bool IsInitialBlockDownload()
nLastUpdate = GetTime();
}
return (GetTime() - nLastUpdate < 10 &&
pindexBest->nTime < GetTime() - 24 * 60 * 60);
pindexBest->GetBlockTime() < GetTime() - 24 * 60 * 60);
}
bool IsLockdown()
@ -884,8 +913,8 @@ void Lockdown(CBlockIndex* pindexNew)
CTxDB().WriteBestInvalidWork(bnBestInvalidWork);
MainFrameRepaint();
}
printf("Lockdown: invalid block=%s height=%d work=%s\n", pindexNew->GetBlockHash().ToString().substr(0,22).c_str(), pindexNew->nHeight, pindexNew->bnChainWork.ToString().c_str());
printf("Lockdown: current best=%s height=%d work=%s\n", hashBestChain.ToString().substr(0,22).c_str(), nBestHeight, bnBestChainWork.ToString().c_str());
printf("Lockdown: invalid block=%s height=%d work=%s\n", pindexNew->GetBlockHash().ToString().substr(0,20).c_str(), pindexNew->nHeight, pindexNew->bnChainWork.ToString().c_str());
printf("Lockdown: current best=%s height=%d work=%s\n", hashBestChain.ToString().substr(0,20).c_str(), nBestHeight, bnBestChainWork.ToString().c_str());
printf("Lockdown: IsLockdown()=%d\n", (IsLockdown() ? 1 : 0));
if (IsLockdown())
printf("Lockdown: WARNING: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.\n");
@ -1008,14 +1037,13 @@ bool CTransaction::ConnectInputs(CTxDB& txdb, map<uint256, CTxIndex>& mapTestPoo
nValueIn += txPrev.vout[prevout.n].nValue;
// Check for negative or overflow input values
if (txPrev.vout[prevout.n].nValue < 0)
return error("ConnectInputs() : txin.nValue negative");
if (txPrev.vout[prevout.n].nValue > MAX_MONEY)
return error("ConnectInputs() : txin.nValue too high");
if (nValueIn > MAX_MONEY)
return error("ConnectInputs() : txin total too high");
if (!MoneyRange(txPrev.vout[prevout.n].nValue) || !MoneyRange(nValueIn))
return error("ConnectInputs() : txin values out of range");
}
if (nValueIn < GetValueOut())
return error("ConnectInputs() : %s value in < value out", GetHash().ToString().substr(0,6).c_str());
// Tally transaction fees
int64 nTxFee = nValueIn - GetValueOut();
if (nTxFee < 0)
@ -1180,7 +1208,7 @@ bool Reorganize(CTxDB& txdb, CBlockIndex* pindexNew)
foreach(CBlockIndex* pindex, vDisconnect)
{
CBlock block;
if (!block.ReadFromDisk(pindex->nFile, pindex->nBlockPos))
if (!block.ReadFromDisk(pindex))
return error("Reorganize() : ReadFromDisk for disconnect failed");
if (!block.DisconnectBlock(txdb, pindex))
return error("Reorganize() : DisconnectBlock failed");
@ -1197,7 +1225,7 @@ bool Reorganize(CTxDB& txdb, CBlockIndex* pindexNew)
{
CBlockIndex* pindex = vConnect[i];
CBlock block;
if (!block.ReadFromDisk(pindex->nFile, pindex->nBlockPos))
if (!block.ReadFromDisk(pindex))
return error("Reorganize() : ReadFromDisk for connect failed");
if (!block.ConnectBlock(txdb, pindex))
{
@ -1283,7 +1311,7 @@ bool CBlock::SetBestChain(CTxDB& txdb, CBlockIndex* pindexNew)
bnBestChainWork = pindexNew->bnChainWork;
nTimeBestReceived = GetTime();
nTransactionsUpdated++;
printf("SetBestChain: new best=%s height=%d work=%s\n", hashBestChain.ToString().substr(0,22).c_str(), nBestHeight, bnBestChainWork.ToString().c_str());
printf("SetBestChain: new best=%s height=%d work=%s\n", hashBestChain.ToString().substr(0,20).c_str(), nBestHeight, bnBestChainWork.ToString().c_str());
return true;
}
@ -1294,7 +1322,7 @@ bool CBlock::AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos)
// Check for duplicate
uint256 hash = GetHash();
if (mapBlockIndex.count(hash))
return error("AddToBlockIndex() : %s already exists", hash.ToString().substr(0,16).c_str());
return error("AddToBlockIndex() : %s already exists", hash.ToString().substr(0,20).c_str());
// Construct new block index object
CBlockIndex* pindexNew = new CBlockIndex(nFile, nBlockPos, *this);
@ -1346,7 +1374,7 @@ bool CBlock::CheckBlock() const
return error("CheckBlock() : size limits failed");
// Check timestamp
if (nTime > GetAdjustedTime() + 2 * 60 * 60)
if (GetBlockTime() > GetAdjustedTime() + 2 * 60 * 60)
return error("CheckBlock() : block timestamp too far in the future");
// First transaction must be coinbase, the rest must not be
@ -1362,10 +1390,8 @@ bool CBlock::CheckBlock() const
return error("CheckBlock() : CheckTransaction failed");
// Check proof of work matches claimed amount
if (CBigNum().SetCompact(nBits) > bnProofOfWorkLimit)
return error("CheckBlock() : nBits below minimum work");
if (GetHash() > CBigNum().SetCompact(nBits).getuint256())
return error("CheckBlock() : hash doesn't match nBits");
if (!CheckProofOfWork(GetHash(), nBits))
return error("CheckBlock() : proof of work failed");
// Check merkleroot
if (hashMerkleRoot != BuildMerkleTree())
@ -1388,12 +1414,12 @@ bool CBlock::AcceptBlock()
CBlockIndex* pindexPrev = (*mi).second;
// Check timestamp against prev
if (nTime <= pindexPrev->GetMedianTimePast())
if (GetBlockTime() <= pindexPrev->GetMedianTimePast())
return error("AcceptBlock() : block's timestamp is too early");
// Check that all transactions are finalized
foreach(const CTransaction& tx, vtx)
if (!tx.IsFinal(pindexPrev->nHeight+1, nTime))
if (!tx.IsFinal(pindexPrev->nHeight+1, GetBlockTime()))
return error("AcceptBlock() : contains a non-final transaction");
// Check proof of work
@ -1442,9 +1468,9 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
// Check for duplicate
uint256 hash = pblock->GetHash();
if (mapBlockIndex.count(hash))
return error("ProcessBlock() : already have block %d %s", mapBlockIndex[hash]->nHeight, hash.ToString().substr(0,16).c_str());
return error("ProcessBlock() : already have block %d %s", mapBlockIndex[hash]->nHeight, hash.ToString().substr(0,20).c_str());
if (mapOrphanBlocks.count(hash))
return error("ProcessBlock() : already have block (orphan) %s", hash.ToString().substr(0,16).c_str());
return error("ProcessBlock() : already have block (orphan) %s", hash.ToString().substr(0,20).c_str());
// Preliminary checks
if (!pblock->CheckBlock())
@ -1456,7 +1482,7 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
// If don't already have its previous block, shunt it off to holding area until we get it
if (!mapBlockIndex.count(pblock->hashPrevBlock))
{
printf("ProcessBlock: ORPHAN BLOCK, prev=%s\n", pblock->hashPrevBlock.ToString().substr(0,16).c_str());
printf("ProcessBlock: ORPHAN BLOCK, prev=%s\n", pblock->hashPrevBlock.ToString().substr(0,20).c_str());
mapOrphanBlocks.insert(make_pair(hash, pblock));
mapOrphanBlocksByPrev.insert(make_pair(pblock->hashPrevBlock, pblock));
@ -1731,8 +1757,8 @@ void PrintBlockTree()
pindex->nHeight,
pindex->nFile,
pindex->nBlockPos,
block.GetHash().ToString().substr(0,16).c_str(),
DateTimeStrFormat("%x %H:%M:%S", block.nTime).c_str(),
block.GetHash().ToString().substr(0,20).c_str(),
DateTimeStrFormat("%x %H:%M:%S", block.GetBlockTime()).c_str(),
block.vtx.size());
CRITICAL_BLOCK(cs_mapWallet)
@ -2157,12 +2183,12 @@ bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
if (pindex)
pindex = pindex->pnext;
int nLimit = 500 + locator.GetDistanceBack();
printf("getblocks %d to %s limit %d\n", (pindex ? pindex->nHeight : -1), hashStop.ToString().substr(0,16).c_str(), nLimit);
printf("getblocks %d to %s limit %d\n", (pindex ? pindex->nHeight : -1), hashStop.ToString().substr(0,20).c_str(), nLimit);
for (; pindex; pindex = pindex->pnext)
{
if (pindex->GetBlockHash() == hashStop)
{
printf(" getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,16).c_str());
printf(" getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str());
break;
}
pfrom->PushInventory(CInv(MSG_BLOCK, pindex->GetBlockHash()));
@ -2170,7 +2196,7 @@ bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
{
// When this block is requested, we'll send an inv that'll make them
// getblocks the next batch of inventory.
printf(" getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,16).c_str());
printf(" getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str());
pfrom->hashContinue = pindex->GetBlockHash();
break;
}
@ -2237,7 +2263,7 @@ bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
vRecv >> *pblock;
//// debug print
printf("received block %s\n", pblock->GetHash().ToString().substr(0,16).c_str());
printf("received block %s\n", pblock->GetHash().ToString().substr(0,20).c_str());
// pblock->print();
CInv inv(MSG_BLOCK, pblock->GetHash());

68
main.h
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@ -19,8 +19,8 @@ static const unsigned int MAX_BLOCK_SIZE = 1000000;
static const int64 COIN = 100000000;
static const int64 CENT = 1000000;
static const int64 MAX_MONEY = 21000000 * COIN;
inline bool MoneyRange(int64 nValue) { return (nValue >= 0 && nValue <= MAX_MONEY); }
static const int COINBASE_MATURITY = 100;
static const CBigNum bnProofOfWorkLimit(~uint256(0) >> 32);
@ -83,6 +83,7 @@ string SendMoneyToBitcoinAddress(string strAddress, int64 nValue, CWalletTx& wtx
void GenerateBitcoins(bool fGenerate);
void ThreadBitcoinMiner(void* parg);
void BitcoinMiner();
bool CheckProofOfWork(uint256 hash, unsigned int nBits);
bool IsInitialBlockDownload();
bool IsLockdown();
@ -338,6 +339,8 @@ public:
int64 GetCredit() const
{
if (!MoneyRange(nValue))
throw runtime_error("CTxOut::GetCredit() : value out of range");
if (IsMine())
return nValue;
return 0;
@ -424,7 +427,7 @@ public:
nBlockHeight = nBestHeight;
if (nBlockTime == 0)
nBlockTime = GetAdjustedTime();
if (nLockTime < (nLockTime < 500000000 ? nBlockHeight : nBlockTime))
if ((int64)nLockTime < (nLockTime < 500000000 ? (int64)nBlockHeight : nBlockTime))
return true;
foreach(const CTxIn& txin, vin)
if (!txin.IsFinal())
@ -481,8 +484,8 @@ public:
if (txout.nValue > MAX_MONEY)
return error("CTransaction::CheckTransaction() : txout.nValue too high");
nValueOut += txout.nValue;
if (nValueOut > MAX_MONEY)
return error("CTransaction::CheckTransaction() : txout total too high");
if (!MoneyRange(nValueOut))
return error("CTransaction::CheckTransaction() : txout total out of range");
}
if (IsCoinBase())
@ -512,7 +515,11 @@ public:
{
int64 nDebit = 0;
foreach(const CTxIn& txin, vin)
{
nDebit += txin.GetDebit();
if (!MoneyRange(nDebit))
throw runtime_error("CTransaction::GetDebit() : value out of range");
}
return nDebit;
}
@ -520,7 +527,11 @@ public:
{
int64 nCredit = 0;
foreach(const CTxOut& txout, vout)
{
nCredit += txout.GetCredit();
if (!MoneyRange(nCredit))
throw runtime_error("CTransaction::GetCredit() : value out of range");
}
return nCredit;
}
@ -529,9 +540,9 @@ public:
int64 nValueOut = 0;
foreach(const CTxOut& txout, vout)
{
if (txout.nValue < 0)
throw runtime_error("CTransaction::GetValueOut() : negative value");
nValueOut += txout.nValue;
if (!MoneyRange(txout.nValue) || !MoneyRange(nValueOut))
throw runtime_error("CTransaction::GetValueOut() : value out of range");
}
return nValueOut;
}
@ -930,6 +941,11 @@ public:
return Hash(BEGIN(nVersion), END(nNonce));
}
int64 GetBlockTime() const
{
return (int64)nTime;
}
uint256 BuildMerkleTree() const
{
@ -1030,10 +1046,8 @@ public:
filein >> *this;
// Check the header
if (CBigNum().SetCompact(nBits) > bnProofOfWorkLimit)
return error("CBlock::ReadFromDisk() : nBits errors in block header");
if (GetHash() > CBigNum().SetCompact(nBits).getuint256())
return error("CBlock::ReadFromDisk() : GetHash() errors in block header");
if (!CheckProofOfWork(GetHash(), nBits))
return error("CBlock::ReadFromDisk() : errors in block header");
return true;
}
@ -1043,9 +1057,9 @@ public:
void print() const
{
printf("CBlock(hash=%s, ver=%d, hashPrevBlock=%s, hashMerkleRoot=%s, nTime=%u, nBits=%08x, nNonce=%u, vtx=%d)\n",
GetHash().ToString().substr(0,16).c_str(),
GetHash().ToString().substr(0,20).c_str(),
nVersion,
hashPrevBlock.ToString().substr(0,16).c_str(),
hashPrevBlock.ToString().substr(0,20).c_str(),
hashMerkleRoot.ToString().substr(0,6).c_str(),
nTime, nBits, nNonce,
vtx.size());
@ -1064,7 +1078,7 @@ public:
int64 GetBlockValue(int nHeight, int64 nFees) const;
bool DisconnectBlock(CTxDB& txdb, CBlockIndex* pindex);
bool ConnectBlock(CTxDB& txdb, CBlockIndex* pindex);
bool ReadFromDisk(const CBlockIndex* blockindex, bool fReadTransactions=true);
bool ReadFromDisk(const CBlockIndex* pindex, bool fReadTransactions=true);
bool SetBestChain(CTxDB& txdb, CBlockIndex* pindexNew);
bool AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos);
bool CheckBlock() const;
@ -1142,8 +1156,15 @@ public:
return *phashBlock;
}
int64 GetBlockTime() const
{
return (int64)nTime;
}
CBigNum GetBlockWork() const
{
if (CBigNum().SetCompact(nBits) <= 0)
return 0;
return (CBigNum(1)<<256) / (CBigNum().SetCompact(nBits)+1);
}
@ -1152,6 +1173,11 @@ public:
return (pnext || this == pindexBest);
}
bool CheckIndex() const
{
return CheckProofOfWork(GetBlockHash(), nBits);
}
bool EraseBlockFromDisk()
{
// Open history file
@ -1171,13 +1197,13 @@ public:
int64 GetMedianTimePast() const
{
unsigned int pmedian[nMedianTimeSpan];
unsigned int* pbegin = &pmedian[nMedianTimeSpan];
unsigned int* pend = &pmedian[nMedianTimeSpan];
int64 pmedian[nMedianTimeSpan];
int64* pbegin = &pmedian[nMedianTimeSpan];
int64* pend = &pmedian[nMedianTimeSpan];
const CBlockIndex* pindex = this;
for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
*(--pbegin) = pindex->nTime;
*(--pbegin) = pindex->GetBlockTime();
sort(pbegin, pend);
return pbegin[(pend - pbegin)/2];
@ -1189,7 +1215,7 @@ public:
for (int i = 0; i < nMedianTimeSpan/2; i++)
{
if (!pindex->pnext)
return nTime;
return GetBlockTime();
pindex = pindex->pnext;
}
return pindex->GetMedianTimePast();
@ -1202,7 +1228,7 @@ public:
return strprintf("CBlockIndex(nprev=%08x, pnext=%08x, nFile=%d, nBlockPos=%-6d nHeight=%d, merkle=%s, hashBlock=%s)",
pprev, pnext, nFile, nBlockPos, nHeight,
hashMerkleRoot.ToString().substr(0,6).c_str(),
GetBlockHash().ToString().substr(0,16).c_str());
GetBlockHash().ToString().substr(0,20).c_str());
}
void print() const
@ -1272,8 +1298,8 @@ public:
str += CBlockIndex::ToString();
str += strprintf("\n hashBlock=%s, hashPrev=%s, hashNext=%s)",
GetBlockHash().ToString().c_str(),
hashPrev.ToString().substr(0,16).c_str(),
hashNext.ToString().substr(0,16).c_str());
hashPrev.ToString().substr(0,20).c_str(),
hashNext.ToString().substr(0,20).c_str());
return str;
}

2
net.h
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@ -424,7 +424,7 @@ public:
string ToString() const
{
return strprintf("%s %s", GetCommand(), hash.ToString().substr(0,16).c_str());
return strprintf("%s %s", GetCommand(), hash.ToString().substr(0,20).c_str());
}
void print() const

View File

@ -20,7 +20,7 @@ class CDataStream;
class CAutoFile;
static const int VERSION = 310;
static const char* pszSubVer = ".3";
static const char* pszSubVer = ".4";
@ -81,6 +81,13 @@ enum
#define READWRITE(obj) (nSerSize += ::SerReadWrite(s, (obj), nType, nVersion, ser_action))
#define READWRITEVER(obj) \
do { \
READWRITE((obj)); \
if ((obj) == 10300) \
(obj) = 300; \
} while (false)