From fad59a2f0f37f5b7f6076fd91be43448e35f4b7e Mon Sep 17 00:00:00 2001
From: MarcoFalke <*~=`'#}+{/-|&$^_@721217.xyz>
Date: Thu, 11 Jul 2024 16:20:06 +0200
Subject: [PATCH] log: LogError with FlatFilePos in UndoReadFromDisk

These errors should never happen in normal operation. If they do,
knowing the FlatFilePos may be useful to determine if data corruption
happened. Also, handle the error pos.IsNull() as part of OpenUndoFile,
because it may as well have happened due to data corruption.

This mirrors the LogError behavior from ReadBlockFromDisk.
---
 src/node/blockstorage.cpp | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index 16d8d256150..fe5762e2c5f 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -703,15 +703,10 @@ bool BlockManager::UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex& in
 {
     const FlatFilePos pos{WITH_LOCK(::cs_main, return index.GetUndoPos())};
 
-    if (pos.IsNull()) {
-        LogError("%s: no undo data available\n", __func__);
-        return false;
-    }
-
     // Open history file to read
     AutoFile filein{OpenUndoFile(pos, true)};
     if (filein.IsNull()) {
-        LogError("%s: OpenUndoFile failed\n", __func__);
+        LogError("%s: OpenUndoFile failed for %s\n", __func__, pos.ToString());
         return false;
     }
 
@@ -723,13 +718,13 @@ bool BlockManager::UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex& in
         verifier >> blockundo;
         filein >> hashChecksum;
     } catch (const std::exception& e) {
-        LogError("%s: Deserialize or I/O error - %s\n", __func__, e.what());
+        LogError("%s: Deserialize or I/O error - %s at %s\n", __func__, e.what(), pos.ToString());
         return false;
     }
 
     // Verify checksum
     if (hashChecksum != verifier.GetHash()) {
-        LogError("%s: Checksum mismatch\n", __func__);
+        LogError("%s: Checksum mismatch at %s\n", __func__, pos.ToString());
         return false;
     }