Fix importmulti failure to return rescan errors

An off-by-one-block bug in importmulti rescan logic could cause it to return
success in an edge case even when a rescan was not successful. The case where
this would happen is if there were multiple blocks in a row with the same
GetBlockTimeMax() value, and the last block was scanned successfully, but one
or more of the earlier blocks was not readable.

1 files changed, 5 insertions, 9 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index ea329d6eb..e93708209 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1456,10 +1456,9 @@ void CWalletTx::GetAmounts(std::list<COutputEntry>& listReceived,
  * from or to us. If fUpdate is true, found transactions that already
  * exist in the wallet will be updated.
  *
- * Returns pointer to the first block in the last contiguous range that was
- * successfully scanned or elided (elided if pIndexStart points at a block
- * before CWallet::nTimeFirstKey). Returns null if there is no such range, or
- * the range doesn't include chainActive.Tip().
+ * Returns null if scan was successful. Otherwise, if a complete rescan was not
+ * possible (due to pruning or corruption), returns pointer to the most recent
+ * block that could not be scanned.
  */
 CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
 {
@@ -1467,7 +1466,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
     const CChainParams& chainParams = Params();
 
     CBlockIndex* pindex = pindexStart;
-    CBlockIndex* ret = pindexStart;
+    CBlockIndex* ret = nullptr;
     {
         LOCK2(cs_main, cs_wallet);
         fAbortRescan = false;
@@ -1495,11 +1494,8 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
                 for (size_t posInBlock = 0; posInBlock < block.vtx.size(); ++posInBlock) {
                     AddToWalletIfInvolvingMe(block.vtx[posInBlock], pindex, posInBlock, fUpdate);
                 }
-                if (!ret) {
-                    ret = pindex;
-                }
             } else {
-                ret = nullptr;
+                ret = pindex;
             }
             pindex = chainActive.Next(pindex);
         }