4 files changed, 99 insertions, 11 deletions

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index e95c71ac8a..8a9e7d1444 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1074,11 +1074,32 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
 
     if (fRescan && fRunScan && requests.size()) {
         CBlockIndex* pindex = nLowestTimestamp > minimumTimestamp ? chainActive.FindEarliestAtLeast(std::max<int64_t>(nLowestTimestamp - 7200, 0)) : chainActive.Genesis();
-
+        CBlockIndex* scannedRange = nullptr;
         if (pindex) {
-            pwalletMain->ScanForWalletTransactions(pindex, true);
+            scannedRange = pwalletMain->ScanForWalletTransactions(pindex, true);
             pwalletMain->ReacceptWalletTransactions();
         }
+
+        if (!scannedRange || scannedRange->nHeight > pindex->nHeight) {
+            std::vector<UniValue> results = response.getValues();
+            response.clear();
+            response.setArray();
+            size_t i = 0;
+            for (const UniValue& request : requests.getValues()) {
+                // If key creation date is within the successfully scanned
+                // range, or if the import result already has an error set, let
+                // the result stand unmodified. Otherwise replace the result
+                // with an error message.
+                if (GetImportTimestamp(request, now) - 7200 >= scannedRange->GetBlockTimeMax() || results.at(i).exists("error")) {
+                    response.push_back(results.at(i));
+                } else {
+                    UniValue result = UniValue(UniValue::VOBJ);
+                    result.pushKV("success", UniValue(false));
+                    result.pushKV("error", JSONRPCError(RPC_MISC_ERROR, strprintf("Failed to rescan before time %d, transactions may be missing.", scannedRange->GetBlockTimeMax())));
+                    response.push_back(std::move(result));
+                }
+            }
+        }
     }
 
     return response;
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index ca086c86a8..d32e8ba06a 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -9,10 +9,16 @@
 #include <utility>
 #include <vector>
 
+#include "rpc/server.h"
+#include "test/test_bitcoin.h"
+#include "validation.h"
 #include "wallet/test/wallet_test_fixture.h"
 
 #include <boost/foreach.hpp>
 #include <boost/test/unit_test.hpp>
+#include <univalue.h>
+
+extern UniValue importmulti(const JSONRPCRequest& request);
 
 // how many times to run all the tests to have a chance to catch errors that only show up with particular random shuffles
 #define RUN_TESTS 100
@@ -355,4 +361,58 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
     empty_wallet();
 }
 
+BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
+{
+    LOCK(cs_main);
+
+    // Cap last block file size, and mine new block in a new block file.
+    CBlockIndex* oldTip = chainActive.Tip();
+    GetBlockFileInfo(oldTip->GetBlockPos().nFile)->nSize = MAX_BLOCKFILE_SIZE;
+    CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
+    CBlockIndex* newTip = chainActive.Tip();
+
+    // Verify ScanForWalletTransactions picks up transactions in both the old
+    // and new block files.
+    {
+        CWallet wallet;
+        LOCK(wallet.cs_wallet);
+        wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
+        BOOST_CHECK_EQUAL(oldTip, wallet.ScanForWalletTransactions(oldTip));
+        BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 100 * COIN);
+    }
+
+    // Prune the older block file.
+    PruneOneBlockFile(oldTip->GetBlockPos().nFile);
+    UnlinkPrunedFiles({oldTip->GetBlockPos().nFile});
+
+    // Verify ScanForWalletTransactions only picks transactions in the new block
+    // file.
+    {
+        CWallet wallet;
+        LOCK(wallet.cs_wallet);
+        wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
+        BOOST_CHECK_EQUAL(newTip, wallet.ScanForWalletTransactions(oldTip));
+        BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 50 * COIN);
+    }
+
+    {
+        CWallet wallet;
+        ::pwalletMain = &wallet;
+        UniValue key;
+        key.setObject();
+        key.pushKV("scriptPubKey", HexStr(GetScriptForRawPubKey(coinbaseKey.GetPubKey())));
+        key.pushKV("timestamp", 0);
+        key.pushKV("internal", UniValue(true));
+        UniValue keys;
+        keys.setArray();
+        keys.push_back(key);
+        JSONRPCRequest request;
+        request.params.setArray();
+        request.params.push_back(keys);
+
+        UniValue response = importmulti(request);
+        BOOST_CHECK_EQUAL(response.write(), strprintf("[{\"success\":false,\"error\":{\"code\":-1,\"message\":\"Failed to rescan before time %d, transactions may be missing.\"}}]", newTip->GetBlockTimeMax()));
+    }
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 8df15a060e..63501b04be 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1545,10 +1545,14 @@ void CWalletTx::GetAccountAmounts(const string& strAccount, CAmount& nReceived,
  * Scan the block chain (starting in pindexStart) for transactions
  * 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.
+ *
  */
-int CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
+CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
 {
-    int ret = 0;
+    CBlockIndex* ret = nullptr;
     int64_t nNow = GetTime();
     const CChainParams& chainParams = Params();
 
@@ -1570,12 +1574,15 @@ int CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
                 ShowProgress(_("Rescanning..."), std::max(1, std::min(99, (int)((GuessVerificationProgress(chainParams.TxData(), pindex) - dProgressStart) / (dProgressTip - dProgressStart) * 100))));
 
             CBlock block;
-            ReadBlockFromDisk(block, pindex, Params().GetConsensus());
-            int posInBlock;
-            for (posInBlock = 0; posInBlock < (int)block.vtx.size(); posInBlock++)
-            {
-                if (AddToWalletIfInvolvingMe(*block.vtx[posInBlock], pindex, posInBlock, fUpdate))
-                    ret++;
+            if (ReadBlockFromDisk(block, pindex, Params().GetConsensus())) {
+                for (size_t posInBlock = 0; posInBlock < block.vtx.size(); ++posInBlock) {
+                    AddToWalletIfInvolvingMe(*block.vtx[posInBlock], pindex, posInBlock, fUpdate);
+                }
+                if (!ret) {
+                    ret = pindex;
+                }
+            } else {
+                ret = nullptr;
             }
             pindex = chainActive.Next(pindex);
             if (GetTime() >= nNow + 60) {
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index a7b15a8441..98e4fb87b9 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -788,7 +788,7 @@ public:
     bool LoadToWallet(const CWalletTx& wtxIn);
     void SyncTransaction(const CTransaction& tx, const CBlockIndex *pindex, int posInBlock) override;
     bool AddToWalletIfInvolvingMe(const CTransaction& tx, const CBlockIndex* pIndex, int posInBlock, bool fUpdate);
-    int ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate = false);
+    CBlockIndex* ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate = false);
     void ReacceptWalletTransactions();
     void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman) override;
     std::vector<uint256> ResendWalletTransactionsBefore(int64_t nTime, CConnman* connman);