Add functions to construct locators without CChain

This introduces an insignificant performance penalty, as it means locator
construction needs to use the skiplist-based CBlockIndex::GetAncestor()
function instead of the lookup-based CChain, but avoids the need for
callers to have access to a relevant CChain object.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/chain.h b/src/chain.h
index cc1d9e2d22..2d3b084b9b 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -473,8 +473,8 @@ public:
     /** Set/initialize a chain with a given tip. */
     void SetTip(CBlockIndex& block);
 
-    /** Return a CBlockLocator that refers to a block in this chain (by default the tip). */
-    CBlockLocator GetLocator(const CBlockIndex* pindex = nullptr) const;
+    /** Return a CBlockLocator that refers to the tip in of this chain. */
+    CBlockLocator GetLocator() const;
 
     /** Find the last common block between this chain and a block index entry. */
     const CBlockIndex* FindFork(const CBlockIndex* pindex) const;
@@ -483,4 +483,10 @@ public:
     CBlockIndex* FindEarliestAtLeast(int64_t nTime, int height) const;
 };
 
+/** Get a locator for a block index entry. */
+CBlockLocator GetLocator(const CBlockIndex* index);
+
+/** Construct a list of hash entries to put in a locator.  */
+std::vector<uint256> LocatorEntries(const CBlockIndex* index);
+
 #endif // BITCOIN_CHAIN_H