fuzz: DisableNextWrite

This is required in the process_message(s) fuzz targets to avoid leaking
the next write time from one run to the next. Also, disable it
completely because it is not needed and due to leveldb-internal
non-determinism.

Author: MarcoFalke

src/test/fuzz/process_message.cpp

@@ -65,6 +65,7 @@ FUZZ_TARGET(process_message, .init = initialize_process_message)
     auto& chainman = static_cast<TestChainstateManager&>(*g_setup->m_node.chainman);
     SetMockTime(1610000000); // any time to successfully reset ibd
     chainman.ResetIbd();
+    chainman.DisableNextWrite();
 
     node::Warnings warnings{};
     NetGroupManager netgroupman{{}};

src/test/fuzz/process_messages.cpp

@@ -55,6 +55,7 @@ FUZZ_TARGET(process_messages, .init = initialize_process_messages)
     auto& chainman = static_cast<TestChainstateManager&>(*g_setup->m_node.chainman);
     SetMockTime(1610000000); // any time to successfully reset ibd
     chainman.ResetIbd();
+    chainman.DisableNextWrite();
 
     node::Warnings warnings{};
     NetGroupManager netgroupman{{}};

src/test/util/validation.cpp

@@ -9,6 +9,15 @@
 #include <validation.h>
 #include <validationinterface.h>
 
+void TestChainstateManager::DisableNextWrite()
+{
+    struct TestChainstate : public Chainstate {
+        void ResetNextWrite() { m_next_write = NodeClock::time_point::max() - 1s; }
+    };
+    for (auto* cs : GetAll()) {
+        static_cast<TestChainstate*>(cs)->ResetNextWrite();
+    }
+}
 void TestChainstateManager::ResetIbd()
 {
     m_cached_finished_ibd = false;

src/test/util/validation.h

@@ -10,6 +10,8 @@
 class CValidationInterface;
 
 struct TestChainstateManager : public ChainstateManager {
+    /** Disable the next write of all chainstates */
+    void DisableNextWrite();
     /** Reset the ibd cache to its initial state */
     void ResetIbd();
     /** Toggle IsInitialBlockDownload from true to false */

src/validation.h

@@ -785,7 +785,7 @@ class Chainstate
         return m_mempool ? &m_mempool->cs : nullptr;
     }
 
-private:
+protected:
     bool ActivateBestChainStep(BlockValidationState& state, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);
     bool ConnectTip(BlockValidationState& state, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions& disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);