refactor: move RewindBlockIndex to CChainState

This is in preparation for multiple chainstate initialization in init.

Author: jamesob

src/init.cpp

@@ -1614,7 +1614,7 @@ bool AppInitMain(NodeContext& node)
                 // It both disconnects blocks based on ::ChainActive(), and drops block data in
                 // BlockIndex() based on lack of available witness data.
                 uiInterface.InitMessage(_("Rewinding blocks...").translated);
-                if (!RewindBlockIndex(chainparams)) {
+                if (!::ChainstateActive().RewindBlockIndex(chainparams)) {
                     strLoadError = _("Unable to rewind the database to a pre-fork state. You will need to redownload the blockchain").translated;
                     break;
                 }

src/validation.cpp

@@ -4538,26 +4538,15 @@ bool CChainState::RewindBlockIndex(const CChainParams& params)
             PruneBlockIndexCandidates();
 
             CheckBlockIndex(params.GetConsensus());
-        }
-    }
-
-    return true;
-}
-
-bool RewindBlockIndex(const CChainParams& params) {
-    if (!::ChainstateActive().RewindBlockIndex(params)) {
-        return false;
-    }
 
-    LOCK(cs_main);
-    if (::ChainActive().Tip() != nullptr) {
-        // FlushStateToDisk can possibly read ::ChainActive(). Be conservative
-        // and skip it here, we're about to -reindex-chainstate anyway, so
-        // it'll get called a bunch real soon.
-        BlockValidationState state;
-        if (!::ChainstateActive().FlushStateToDisk(params, state, FlushStateMode::ALWAYS)) {
-            LogPrintf("RewindBlockIndex: unable to flush state to disk (%s)\n", state.ToString());
-            return false;
+            // FlushStateToDisk can possibly read ::ChainActive(). Be conservative
+            // and skip it here, we're about to -reindex-chainstate anyway, so
+            // it'll get called a bunch real soon.
+            BlockValidationState state;
+            if (!FlushStateToDisk(params, state, FlushStateMode::ALWAYS)) {
+                LogPrintf("RewindBlockIndex: unable to flush state to disk (%s)\n", state.ToString());
+                return false;
+            }
         }
     }
 

src/validation.h

@@ -380,9 +380,6 @@ bool TestBlockValidity(BlockValidationState& state, const CChainParams& chainpar
  *  Note that transaction witness validation rules are always enforced when P2SH is enforced. */
 bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& params);
 
-/** When there are blocks in the active chain with missing data, rewind the chainstate and remove them from the block index */
-bool RewindBlockIndex(const CChainParams& params) LOCKS_EXCLUDED(cs_main);
-
 /** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
 int GetWitnessCommitmentIndex(const CBlock& block);