Bugfix: only track UTXO modification after lookup

Otherwise, if CCoinsViewCache::ModifyCoins throws an exception in between
setting hasModifier and constructing the CCoinsModifier, the cache ends up
in an inconsistent state, resulting in an assert failure in the next
modification.

Bug discovered by Wladimir J. van der Laan.

Rebased-From: 1c52aad540
Github-Pull: #5597
This commit is contained in:
Pieter Wuille 2015-01-04 17:15:02 +01:00 committed by Wladimir J. van der Laan
parent 3022e7df2a
commit 008138c04a
No known key found for this signature in database
GPG Key ID: 74810B012346C9A6

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@ -106,7 +106,6 @@ bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const {
CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
assert(!hasModifier);
hasModifier = true;
std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
if (ret.second) {
if (!base->GetCoins(txid, ret.first->second.coins)) {
@ -247,7 +246,10 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
return tx.ComputePriority(dResult);
}
CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_) : cache(cache_), it(it_) {}
CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_) : cache(cache_), it(it_) {
assert(!cache.hasModifier);
cache.hasModifier = true;
}
CCoinsModifier::~CCoinsModifier()
{