Move FindForkInGlobalIndex from BlockManager to CChainState

The helper was moved in commit b026e31,
which also mentioned that it could be moved to CChainState. So do that,
as the functionality is not block-storage related.

This also allows to drop one function argument.

src/index/base.cpp

@@ -65,7 +65,7 @@ bool BaseIndex::Init()
     if (locator.IsNull()) {
         m_best_block_index = nullptr;
     } else {
-        m_best_block_index = m_chainstate->m_blockman.FindForkInGlobalIndex(active_chain, locator);
+        m_best_block_index = m_chainstate->FindForkInGlobalIndex(locator);
     }
     m_synced = m_best_block_index.load() == active_chain.Tip();
     if (!m_synced) {

src/net_processing.cpp

@@ -3083,7 +3083,7 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         LOCK(cs_main);
 
         // Find the last block the caller has in the main chain
-        const CBlockIndex* pindex = m_chainman.m_blockman.FindForkInGlobalIndex(m_chainman.ActiveChain(), locator);
+        const CBlockIndex* pindex = m_chainman.ActiveChainstate().FindForkInGlobalIndex(locator);
 
         // Send the rest of the chain
         if (pindex)
@@ -3203,7 +3203,7 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         else
         {
             // Find the last block the caller has in the main chain
-            pindex = m_chainman.m_blockman.FindForkInGlobalIndex(m_chainman.ActiveChain(), locator);
+            pindex = m_chainman.ActiveChainstate().FindForkInGlobalIndex(locator);
             if (pindex)
                 pindex = m_chainman.ActiveChain().Next(pindex);
         }

src/node/interfaces.cpp

@@ -494,8 +494,8 @@ class ChainImpl : public Chain
     std::optional<int> findLocatorFork(const CBlockLocator& locator) override
     {
         LOCK(cs_main);
-        const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        if (CBlockIndex* fork = m_node.chainman->m_blockman.FindForkInGlobalIndex(active, locator)) {
+        const CChainState& active = Assert(m_node.chainman)->ActiveChainstate();
+        if (CBlockIndex* fork = active.FindForkInGlobalIndex(locator)) {
             return fork->nHeight;
         }
         return std::nullopt;

src/validation.cpp

@@ -155,23 +155,24 @@ CBlockIndex* BlockManager::LookupBlockIndex(const uint256& hash) const
     return it == m_block_index.end() ? nullptr : it->second;
 }
 
-CBlockIndex* BlockManager::FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
+CBlockIndex* CChainState::FindForkInGlobalIndex(const CBlockLocator& locator) const
 {
     AssertLockHeld(cs_main);
 
     // Find the latest block common to locator and chain - we expect that
     // locator.vHave is sorted descending by height.
     for (const uint256& hash : locator.vHave) {
-        CBlockIndex* pindex = LookupBlockIndex(hash);
+        CBlockIndex* pindex{m_blockman.LookupBlockIndex(hash)};
         if (pindex) {
-            if (chain.Contains(pindex))
+            if (m_chain.Contains(pindex)) {
                 return pindex;
-            if (pindex->GetAncestor(chain.Height()) == chain.Tip()) {
-                return chain.Tip();
+            }
+            if (pindex->GetAncestor(m_chain.Height()) == m_chain.Tip()) {
+                return m_chain.Tip();
             }
         }
     }
-    return chain.Genesis();
+    return m_chain.Genesis();
 }
 
 bool CheckInputScripts(const CTransaction& tx, TxValidationState& state,

src/validation.h

@@ -466,9 +466,6 @@ class BlockManager
 
     CBlockIndex* LookupBlockIndex(const uint256& hash) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
-    /** Find the last common block between the parameter chain and a locator. */
-    CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
-
     //! Returns last CBlockIndex* that is a checkpoint
     CBlockIndex* GetLastCheckpoint(const CCheckpointData& data) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
@@ -756,6 +753,9 @@ class CChainState
     /** Check whether we are doing an initial block download (synchronizing from disk or network) */
     bool IsInitialBlockDownload() const;
 
+    /** Find the last common block of this chain and a locator. */
+    CBlockIndex* FindForkInGlobalIndex(const CBlockLocator& locator) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
     /**
      * Make various assertions about the state of the block index.
      *