refactor: Move early loadtxoutset checks into ActiveSnapshot

Also changes the return type of ActiveSnapshot to allow returning the
error message to the user of the loadtxoutset RPC.

1 files changed, 22 insertions, 8 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index c34d60f137..53db1cb5b1 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -5647,23 +5647,38 @@ Chainstate& ChainstateManager::InitializeChainstate(CTxMemPool* mempool)
     return destroyed && !fs::exists(db_path);
 }
 
-bool ChainstateManager::ActivateSnapshot(
+util::Result<void> ChainstateManager::ActivateSnapshot(
         AutoFile& coins_file,
         const SnapshotMetadata& metadata,
         bool in_memory)
 {
     uint256 base_blockhash = metadata.m_base_blockhash;
+    int base_blockheight = metadata.m_base_blockheight;
 
     if (this->SnapshotBlockhash()) {
-        LogPrintf("[snapshot] can't activate a snapshot-based chainstate more than once\n");
-        return false;
+        return util::Error{_("Can't activate a snapshot-based chainstate more than once")};
     }
 
     {
         LOCK(::cs_main);
+
+        if (!GetParams().AssumeutxoForBlockhash(base_blockhash).has_value()) {
+            auto available_heights = GetParams().GetAvailableSnapshotHeights();
+            std::string heights_formatted = util::Join(available_heights, ", ", [&](const auto& i) { return util::ToString(i); });
+            return util::Error{strprintf(_("assumeutxo block hash in snapshot metadata not recognized (hash: %s, height: %s). The following snapshot heights are available: %s."),
+                base_blockhash.ToString(),
+                base_blockheight,
+                heights_formatted)};
+        }
+
+        CBlockIndex* snapshot_start_block = m_blockman.LookupBlockIndex(base_blockhash);
+        if (!snapshot_start_block) {
+            return util::Error{strprintf(_("The base block header (%s) must appear in the headers chain. Make sure all headers are syncing, and call loadtxoutset again."),
+                          base_blockhash.ToString())};
+        }
+
         if (Assert(m_active_chainstate->GetMempool())->size() > 0) {
-            LogPrintf("[snapshot] can't activate a snapshot when mempool not empty\n");
-            return false;
+            return util::Error{_("Can't activate a snapshot when mempool not empty.")};
         }
     }
 
@@ -5713,7 +5728,6 @@ bool ChainstateManager::ActivateSnapshot(
     }
 
     auto cleanup_bad_snapshot = [&](const char* reason) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
-        LogPrintf("[snapshot] activation failed - %s\n", reason);
         this->MaybeRebalanceCaches();
 
         // PopulateAndValidateSnapshot can return (in error) before the leveldb datadir
@@ -5729,7 +5743,7 @@ bool ChainstateManager::ActivateSnapshot(
                     "Manually remove it before restarting.\n"), fs::PathToString(*snapshot_datadir)));
             }
         }
-        return false;
+        return util::Error{_(reason)};
     };
 
     if (!this->PopulateAndValidateSnapshot(*snapshot_chainstate, coins_file, metadata)) {
@@ -5772,7 +5786,7 @@ bool ChainstateManager::ActivateSnapshot(
         m_snapshot_chainstate->CoinsTip().DynamicMemoryUsage() / (1000 * 1000));
 
     this->MaybeRebalanceCaches();
-    return true;
+    return {};
 }
 
 static void FlushSnapshotToDisk(CCoinsViewCache& coins_cache, bool snapshot_loaded)