blockstorage, refactor: pass GetFirstStoredBlock() start_block by reference

instead of by pointer, so as to not accept a nullptr.

Author: jonatack

src/index/base.cpp

@@ -75,7 +75,7 @@ bool BaseIndex::Init()
         if (!m_best_block_index) {
             // index is not built yet
             // make sure we have all block data back to the genesis
-            prune_violation = m_chainstate->m_blockman.GetFirstStoredBlock(active_chain.Tip()) != active_chain.Genesis();
+            prune_violation = m_chainstate->m_blockman.GetFirstStoredBlock(*active_chain.Tip()) != active_chain.Genesis();
         }
         // in case the index has a best block set and is not fully synced
         // check if we have the required blocks to continue building the index

src/node/blockstorage.cpp

@@ -390,11 +390,10 @@ bool BlockManager::IsBlockPruned(const CBlockIndex* pblockindex)
     return (m_have_pruned && !(pblockindex->nStatus & BLOCK_HAVE_DATA) && pblockindex->nTx > 0);
 }
 
-const CBlockIndex* BlockManager::GetFirstStoredBlock(const CBlockIndex* start_block)
+const CBlockIndex* BlockManager::GetFirstStoredBlock(const CBlockIndex& start_block)
 {
     AssertLockHeld(::cs_main);
-    assert(start_block);
-    const CBlockIndex* last_block = start_block;
+    const CBlockIndex* last_block = &start_block;
     while (last_block->pprev && (last_block->pprev->nStatus & BLOCK_HAVE_DATA)) {
         last_block = last_block->pprev;
     }

src/node/blockstorage.h

@@ -179,7 +179,7 @@ class BlockManager
     const CBlockIndex* GetLastCheckpoint(const CCheckpointData& data) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     //! Find the first block that is not pruned
-    const CBlockIndex* GetFirstStoredBlock(const CBlockIndex* start_block) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
+    const CBlockIndex* GetFirstStoredBlock(const CBlockIndex& start_block) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     /** True if any block files have ever been pruned. */
     bool m_have_pruned = false;

src/rpc/blockchain.cpp

@@ -760,8 +760,9 @@ static RPCHelpMan pruneblockchain()
     CChain& active_chain = active_chainstate.m_chain;
 
     int heightParam = request.params[0].get_int();
-    if (heightParam < 0)
+    if (heightParam < 0) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Negative block height.");
+    }
 
     // Height value more than a billion is too high to be a block height, and
     // too low to be a block time (corresponds to timestamp from Sep 2001).
@@ -786,7 +787,7 @@ static RPCHelpMan pruneblockchain()
     }
 
     PruneBlockFilesManual(active_chainstate, height);
-    const CBlockIndex* block = CHECK_NONFATAL(active_chain.Tip());
+    const CBlockIndex& block{*CHECK_NONFATAL(active_chain.Tip())};
     const CBlockIndex* last_block{active_chainstate.m_blockman.GetFirstStoredBlock(block)};
 
     return static_cast<uint64_t>(last_block->nHeight);
@@ -1215,7 +1216,7 @@ RPCHelpMan getblockchaininfo()
     obj.pushKV("size_on_disk", chainman.m_blockman.CalculateCurrentUsage());
     obj.pushKV("pruned", node::fPruneMode);
     if (node::fPruneMode) {
-        obj.pushKV("pruneheight", chainman.m_blockman.GetFirstStoredBlock(&tip)->nHeight);
+        obj.pushKV("pruneheight", chainman.m_blockman.GetFirstStoredBlock(tip)->nHeight);
 
         // if 0, execution bypasses the whole if block.
         bool automatic_pruning{args.GetIntArg("-prune", 0) != 1};