From 069ccfcbc4e8b2ec9dd6cb128a18ba2bee1c8929 Mon Sep 17 00:00:00 2001
From: Aaron Dewes <aaron.dewes@web.de>
Date: Wed, 26 May 2021 09:32:17 +0200
Subject: [PATCH] Add reindex=auto flag to automatically reindex corrupt data

This PR allows the reindex flag to be set to auto, which automatically starts a reindex if the chain state or block index are corrupt.
This can be especially useful for  Raspberry Pi based full nodes, which often experience power outages or similar issues which can corrupt data.
It allows full node operators to make Bitcoin Core reindex automatically, without having to worry about removing the reindex flag again. (Which isn't much effort, but can be annoying to forget)

Github-Pull: #22072
Rebased-From: 602f4da9178dff11853431f9a7115194f6a016ac
---
 src/init.cpp | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/init.cpp b/src/init.cpp
index 20cb483a3a..534e9eb6e2 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -434,7 +434,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-prune=<n>", strprintf("Reduce storage requirements by enabling pruning (deleting) of old blocks. This allows the pruneblockchain RPC to be called to delete specific blocks and enables automatic pruning of old blocks if a target size in MiB is provided. This mode is incompatible with -txindex. "
             "Warning: Reverting this setting requires re-downloading the entire blockchain. "
             "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >=%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-reindex", "Rebuild chain state and block index from the blk*.dat files on disk. This will also rebuild active optional indexes.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-reindex", "Rebuild chain state and block index from the blk*.dat files on disk. This will also rebuild active optional indexes. Setting this to auto automatically reindexes the block database if it is corrupted.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-reindex-chainstate", "Rebuild chain state from the currently indexed blocks. When in pruning mode or if blocks on disk might be corrupted, use full -reindex instead. Deactivate all optional indexes before running this.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-settings=<file>", strprintf("Specify path to dynamic settings data file. Can be disabled with -nosettings. File is written at runtime and not meant to be edited by users (use %s instead for custom settings). Relative paths will be prefixed by datadir location. (default: %s)", BITCOIN_CONF_FILENAME, BITCOIN_SETTINGS_FILENAME), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #if HAVE_SYSTEM
@@ -1380,6 +1380,8 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
 
     // ********************************************************* Step 7: load block chain
 
+    // If reindex=auto, then this returns false, which is intentional,
+    // because we check for auto only if corruption is detected
     fReindex = args.GetBoolArg("-reindex", false);
     bool fReindexChainState = args.GetBoolArg("-reindex-chainstate", false);
 
@@ -1468,12 +1470,20 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
         }
 
         if (!fLoaded && !ShutdownRequested()) {
-            // first suggest a reindex
+            // If reindex=auto, directly start the reindex
+            bool fAutoReindex = (args.GetArg("-reindex", "0") == "auto");
             if (!options.reindex) {
-                bool fRet = uiInterface.ThreadSafeQuestion(
-                    error + Untranslated(".\n\n") + _("Do you want to rebuild the block database now?"),
-                    error.original + ".\nPlease restart with -reindex or -reindex-chainstate to recover.",
-                    "", CClientUIInterface::MSG_ERROR | CClientUIInterface::BTN_ABORT);
+                bool fRet;
+                if(!fAutoReindex) {
+                    // suggest a reindex to GUI users
+                    fRet = uiInterface.ThreadSafeQuestion(
+                        error + Untranslated(".\n\n") + _("Do you want to rebuild the block database now?"),
+                        error.original + ".\nPlease restart with -reindex or -reindex-chainstate to recover.",
+                        "", CClientUIInterface::MSG_ERROR | CClientUIInterface::BTN_ABORT);
+                } else {
+                    LogPrintf("Automatically running a reindex.\n");
+                    fRet = true;
+                }
                 if (fRet) {
                     fReindex = true;
                     AbortShutdown();