allow exporting outputs in chunks

this will make it easier huge wallets to do so without hitting
random limits (eg, max string size in node).

13 files changed, 348 insertions, 72 deletions

diff --git a/src/device_trezor/device_trezor.cpp b/src/device_trezor/device_trezor.cpp
index 6f7ae9a6b..9065cf0bb 100644
--- a/src/device_trezor/device_trezor.cpp
+++ b/src/device_trezor/device_trezor.cpp
@@ -511,7 +511,7 @@ namespace trezor {
                                 tools::wallet2::signed_tx_set & signed_tx,
                                 hw::tx_aux_data & aux_data)
     {
-      CHECK_AND_ASSERT_THROW_MES(unsigned_tx.transfers.first == 0, "Unsuported non zero offset");
+      CHECK_AND_ASSERT_THROW_MES(std::get<0>(unsigned_tx.transfers) == 0, "Unsuported non zero offset");
 
       TREZOR_AUTO_LOCK_CMD();
       require_connected();
@@ -522,7 +522,7 @@ namespace trezor {
       const size_t num_tx = unsigned_tx.txes.size();
       m_num_transations_to_sign = num_tx;
       signed_tx.key_images.clear();
-      signed_tx.key_images.resize(unsigned_tx.transfers.second.size());
+      signed_tx.key_images.resize(std::get<2>(unsigned_tx.transfers).size());
 
       for(size_t tx_idx = 0; tx_idx < num_tx; ++tx_idx) {
         std::shared_ptr<protocol::tx::Signer> signer;
@@ -566,8 +566,8 @@ namespace trezor {
         cpend.key_images = key_images;
 
         // KI sync
-        for(size_t cidx=0, trans_max=unsigned_tx.transfers.second.size(); cidx < trans_max; ++cidx){
-          signed_tx.key_images[cidx] = unsigned_tx.transfers.second[cidx].m_key_image;
+        for(size_t cidx=0, trans_max=std::get<2>(unsigned_tx.transfers).size(); cidx < trans_max; ++cidx){
+          signed_tx.key_images[cidx] = std::get<2>(unsigned_tx.transfers)[cidx].m_key_image;
         }
 
         size_t num_sources = cdata.tx_data.sources.size();
@@ -579,9 +579,9 @@ namespace trezor {
           CHECK_AND_ASSERT_THROW_MES(src_idx < cdata.tx.vin.size(), "Invalid idx_mapped");
 
           size_t idx_map_src = cdata.tx_data.selected_transfers[idx_mapped];
-          CHECK_AND_ASSERT_THROW_MES(idx_map_src >= unsigned_tx.transfers.first, "Invalid offset");
+          CHECK_AND_ASSERT_THROW_MES(idx_map_src >= std::get<0>(unsigned_tx.transfers), "Invalid offset");
 
-          idx_map_src -= unsigned_tx.transfers.first;
+          idx_map_src -= std::get<0>(unsigned_tx.transfers);
           CHECK_AND_ASSERT_THROW_MES(idx_map_src < signed_tx.key_images.size(), "Invalid key image index");
 
           const auto vini = boost::get<cryptonote::txin_to_key>(cdata.tx.vin[src_idx]);
diff --git a/src/device_trezor/trezor/protocol.hpp b/src/device_trezor/trezor/protocol.hpp
index 858db1520..aa4b3a305 100644
--- a/src/device_trezor/trezor/protocol.hpp
+++ b/src/device_trezor/trezor/protocol.hpp
@@ -232,8 +232,8 @@ namespace tx {
     }
 
     const tools::wallet2::transfer_details & get_transfer(size_t idx) const {
-      CHECK_AND_ASSERT_THROW_MES(idx < m_unsigned_tx->transfers.second.size() + m_unsigned_tx->transfers.first && idx >= m_unsigned_tx->transfers.first, "Invalid transfer index");
-      return m_unsigned_tx->transfers.second[idx - m_unsigned_tx->transfers.first];
+      CHECK_AND_ASSERT_THROW_MES(idx < std::get<2>(m_unsigned_tx->transfers).size() + std::get<0>(m_unsigned_tx->transfers) && idx >= std::get<0>(m_unsigned_tx->transfers), "Invalid transfer index");
+      return std::get<2>(m_unsigned_tx->transfers)[idx - std::get<0>(m_unsigned_tx->transfers)];
     }
 
     const tools::wallet2::transfer_details & get_source_transfer(size_t idx) const {
diff --git a/src/serialization/tuple.h b/src/serialization/tuple.h
new file mode 100644
index 000000000..6d98e05b0
--- /dev/null
+++ b/src/serialization/tuple.h
@@ -0,0 +1,169 @@
+// Copyright (c) 2014-2020, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// 
+// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
+
+#pragma once
+#include <memory>
+#include "serialization.h"
+
+namespace serialization
+{
+  namespace detail
+  {
+    template <typename Archive, class T>
+    bool serialize_tuple_element(Archive& ar, T& e)
+    {
+      return ::do_serialize(ar, e);
+    }
+
+    template <typename Archive>
+    bool serialize_tuple_element(Archive& ar, uint64_t& e)
+    {
+      ar.serialize_varint(e);
+      return true;
+    }
+  }
+}
+
+template <template <bool> class Archive, class E0, class E1, class E2>
+inline bool do_serialize(Archive<false>& ar, std::tuple<E0,E1,E2>& p)
+{
+  size_t cnt;
+  ar.begin_array(cnt);
+  if (!ar.good())
+    return false;
+  if (cnt != 3)
+    return false;
+
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<0>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<1>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<2>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+
+  ar.end_array();
+  return true;
+}
+
+template <template <bool> class Archive, class E0, class E1, class E2>
+inline bool do_serialize(Archive<true>& ar, std::tuple<E0,E1,E2>& p)
+{
+  ar.begin_array(3);
+  if (!ar.good())
+    return false;
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<0>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<1>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<2>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.end_array();
+  return true;
+}
+
+template <template <bool> class Archive, class E0, class E1, class E2, class E3>
+inline bool do_serialize(Archive<false>& ar, std::tuple<E0,E1,E2,E3>& p)
+{
+  size_t cnt;
+  ar.begin_array(cnt);
+  if (!ar.good())
+    return false;
+  if (cnt != 4)
+    return false;
+
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<0>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<1>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<2>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if (!::serialization::detail::serialize_tuple_element(ar, std::get<3>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+
+  ar.end_array();
+  return true;
+}
+
+template <template <bool> class Archive, class E0, class E1, class E2, class E3>
+inline bool do_serialize(Archive<true>& ar, std::tuple<E0,E1,E2,E3>& p)
+{
+  ar.begin_array(4);
+  if (!ar.good())
+    return false;
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<0>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<1>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<2>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.delimit_array();
+  if(!::serialization::detail::serialize_tuple_element(ar, std::get<3>(p)))
+    return false;
+  if (!ar.good())
+    return false;
+  ar.end_array();
+  return true;
+}
+
diff --git a/src/simplewallet/simplewallet.cpp b/src/simplewallet/simplewallet.cpp
index a8f4e5a07..9b63ceca6 100644
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@@ -7912,8 +7912,10 @@ bool simple_wallet::accept_loaded_tx(const std::function<size_t()> get_num_txes,
 bool simple_wallet::accept_loaded_tx(const tools::wallet2::unsigned_tx_set &txs)
 {
   std::string extra_message;
-  if (!txs.transfers.second.empty())
-    extra_message = (boost::format("%u outputs to import. ") % (unsigned)txs.transfers.second.size()).str();
+  if (!std::get<2>(txs.new_transfers).empty())
+    extra_message = (boost::format("%u outputs to import. ") % (unsigned)std::get<2>(txs.new_transfers).size()).str();
+  else if (!std::get<2>(txs.transfers).empty())
+    extra_message = (boost::format("%u outputs to import. ") % (unsigned)std::get<2>(txs.transfers).size()).str();
   return accept_loaded_tx([&txs](){return txs.txes.size();}, [&txs](size_t n)->const tools::wallet2::tx_construction_data&{return txs.txes[n];}, extra_message);
 }
 //----------------------------------------------------------------------------------------------------
diff --git a/src/wallet/api/wallet.cpp b/src/wallet/api/wallet.cpp
index 1ee2e20b6..807dba33b 100644
--- a/src/wallet/api/wallet.cpp
+++ b/src/wallet/api/wallet.cpp
@@ -1146,8 +1146,8 @@ UnsignedTransaction *WalletImpl::loadUnsignedTx(const std::string &unsigned_file
   
   // Check tx data and construct confirmation message
   std::string extra_message;
-  if (!transaction->m_unsigned_tx_set.transfers.second.empty())
-    extra_message = (boost::format("%u outputs to import. ") % (unsigned)transaction->m_unsigned_tx_set.transfers.second.size()).str();
+  if (!std::get<2>(transaction->m_unsigned_tx_set.transfers).empty())
+    extra_message = (boost::format("%u outputs to import. ") % (unsigned)std::get<2>(transaction->m_unsigned_tx_set.transfers).size()).str();
   transaction->checkLoadedTx([&transaction](){return transaction->m_unsigned_tx_set.txes.size();}, [&transaction](size_t n)->const tools::wallet2::tx_construction_data&{return transaction->m_unsigned_tx_set.txes[n];}, extra_message);
   setStatus(transaction->status(), transaction->errorString());
     
diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 536460396..05d86a817 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -6604,9 +6604,9 @@ bool wallet2::sign_tx(const std::string &unsigned_filename, const std::string &s
 //----------------------------------------------------------------------------------------------------
 bool wallet2::sign_tx(unsigned_tx_set &exported_txs, std::vector<wallet2::pending_tx> &txs, signed_tx_set &signed_txes)
 {
-  if (!exported_txs.new_transfers.second.empty())
+  if (!std::get<2>(exported_txs.new_transfers).empty())
     import_outputs(exported_txs.new_transfers);
-  else if (!exported_txs.transfers.second.empty())
+  else if (!std::get<2>(exported_txs.transfers).empty())
     import_outputs(exported_txs.transfers);
 
   // sign the transactions
@@ -10800,7 +10800,7 @@ void wallet2::cold_sign_tx(const std::vector<pending_tx>& ptx_vector, signed_tx_
   {
     txs.txes.push_back(get_construction_data_with_decrypted_short_payment_id(tx, m_account.get_device()));
   }
-  txs.transfers = std::make_pair(0, m_transfers);
+  txs.transfers = std::make_tuple(0, m_transfers.size(), m_transfers);
 
   auto dev_cold = dynamic_cast<::hw::device_cold*>(&hwdev);
   CHECK_AND_ASSERT_THROW_MES(dev_cold, "Device does not implement cold signing interface");
@@ -13103,18 +13103,29 @@ void wallet2::import_blockchain(const std::tuple<size_t, crypto::hash, std::vect
   m_last_block_reward = cryptonote::get_outs_money_amount(genesis.miner_tx);
 }
 //----------------------------------------------------------------------------------------------------
-std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> wallet2::export_outputs(bool all) const
+std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::exported_transfer_details>> wallet2::export_outputs(bool all, uint32_t start, uint32_t count) const
 {
   PERF_TIMER(export_outputs);
   std::vector<tools::wallet2::exported_transfer_details> outs;
 
+  // invalid cases
+  THROW_WALLET_EXCEPTION_IF(count == 0, error::wallet_internal_error, "Nothing requested");
+  THROW_WALLET_EXCEPTION_IF(!all && start > 0, error::wallet_internal_error, "Incremental mode is incompatible with non-zero start");
+
+  // valid cases:
+  // all: all outputs, subject to start/count
+  // !all: incremental, subject to count
+  // for convenience, start/count are allowed to go past the valid range, then nothing is returned
+
   size_t offset = 0;
   if (!all)
     while (offset < m_transfers.size() && (m_transfers[offset].m_key_image_known && !m_transfers[offset].m_key_image_request))
       ++offset;
+  else
+    offset = start;
 
   outs.reserve(m_transfers.size() - offset);
-  for (size_t n = offset; n < m_transfers.size(); ++n)
+  for (size_t n = offset; n < m_transfers.size() && n - offset < count; ++n)
   {
     const transfer_details &td = m_transfers[n];
 
@@ -13138,16 +13149,16 @@ std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> wall
     outs.push_back(etd);
   }
 
-  return std::make_pair(offset, outs);
+  return std::make_tuple(offset, m_transfers.size(), outs);
 }
 //----------------------------------------------------------------------------------------------------
-std::string wallet2::export_outputs_to_str(bool all) const
+std::string wallet2::export_outputs_to_str(bool all, uint32_t start, uint32_t count) const
 {
   PERF_TIMER(export_outputs_to_str);
 
   std::stringstream oss;
   binary_archive<true> ar(oss);
-  auto outputs = export_outputs(all);
+  auto outputs = export_outputs(all, start, count);
   THROW_WALLET_EXCEPTION_IF(!::serialization::serialize(ar, outputs), error::wallet_internal_error, "Failed to serialize output data");
 
   std::string magic(OUTPUT_EXPORT_FILE_MAGIC, strlen(OUTPUT_EXPORT_FILE_MAGIC));
@@ -13160,23 +13171,34 @@ std::string wallet2::export_outputs_to_str(bool all) const
   return magic + ciphertext;
 }
 //----------------------------------------------------------------------------------------------------
-size_t wallet2::import_outputs(const std::pair<uint64_t, std::vector<tools::wallet2::transfer_details>> &outputs)
+size_t wallet2::import_outputs(const std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::transfer_details>> &outputs)
 {
   PERF_TIMER(import_outputs);
 
   THROW_WALLET_EXCEPTION_IF(!m_offline, error::wallet_internal_error, "Hot wallets cannot import outputs");
 
-  THROW_WALLET_EXCEPTION_IF(outputs.first > m_transfers.size(), error::wallet_internal_error,
+  // we can now import piecemeal
+  const size_t offset = std::get<0>(outputs);
+  const size_t num_outputs = std::get<1>(outputs);
+  const std::vector<tools::wallet2::transfer_details> &output_array = std::get<2>(outputs);
+
+  THROW_WALLET_EXCEPTION_IF(offset > m_transfers.size(), error::wallet_internal_error,
       "Imported outputs omit more outputs that we know of");
 
-  const size_t offset = outputs.first;
+  THROW_WALLET_EXCEPTION_IF(offset >= num_outputs, error::wallet_internal_error,
+      "Offset is larger than total outputs");
+  THROW_WALLET_EXCEPTION_IF(output_array.size() > num_outputs - offset, error::wallet_internal_error,
+      "Offset is larger than total outputs");
+
   const size_t original_size = m_transfers.size();
-  m_transfers.resize(offset + outputs.second.size());
-  for (size_t i = 0; i < offset; ++i)
-    m_transfers[i].m_key_image_request = false;
-  for (size_t i = 0; i < outputs.second.size(); ++i)
+  if (offset + output_array.size() > m_transfers.size())
+    m_transfers.resize(offset + output_array.size());
+  else if (num_outputs < m_transfers.size())
+    m_transfers.resize(num_outputs);
+
+  for (size_t i = 0; i < output_array.size(); ++i)
   {
-    transfer_details td = outputs.second[i];
+    transfer_details td = output_array[i];
 
     // skip those we've already imported, or which have different data
     if (i + offset < original_size)
@@ -13228,23 +13250,34 @@ process:
   return m_transfers.size();
 }
 //----------------------------------------------------------------------------------------------------
-size_t wallet2::import_outputs(const std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> &outputs)
+size_t wallet2::import_outputs(const std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::exported_transfer_details>> &outputs)
 {
   PERF_TIMER(import_outputs);
 
   THROW_WALLET_EXCEPTION_IF(!m_offline, error::wallet_internal_error, "Hot wallets cannot import outputs");
 
-  THROW_WALLET_EXCEPTION_IF(outputs.first > m_transfers.size(), error::wallet_internal_error,
+  // we can now import piecemeal
+  const size_t offset = std::get<0>(outputs);
+  const size_t num_outputs = std::get<1>(outputs);
+  const std::vector<tools::wallet2::exported_transfer_details> &output_array = std::get<2>(outputs);
+
+  THROW_WALLET_EXCEPTION_IF(offset > m_transfers.size(), error::wallet_internal_error,
       "Imported outputs omit more outputs that we know of. Try using export_outputs all.");
 
-  const size_t offset = outputs.first;
+  THROW_WALLET_EXCEPTION_IF(offset >= num_outputs, error::wallet_internal_error,
+      "Offset is larger than total outputs");
+  THROW_WALLET_EXCEPTION_IF(output_array.size() > num_outputs - offset, error::wallet_internal_error,
+      "Offset is larger than total outputs");
+
   const size_t original_size = m_transfers.size();
-  m_transfers.resize(offset + outputs.second.size());
-  for (size_t i = 0; i < offset; ++i)
-    m_transfers[i].m_key_image_request = false;
-  for (size_t i = 0; i < outputs.second.size(); ++i)
+  if (offset + output_array.size() > m_transfers.size())
+    m_transfers.resize(offset + output_array.size());
+  else if (num_outputs < m_transfers.size())
+    m_transfers.resize(num_outputs);
+
+  for (size_t i = 0; i < output_array.size(); ++i)
   {
-    exported_transfer_details etd = outputs.second[i];
+    exported_transfer_details etd = output_array[i];
     transfer_details &td = m_transfers[i + offset];
 
     // setup td with "cheap" loaded data
@@ -13358,7 +13391,7 @@ size_t wallet2::import_outputs_from_str(const std::string &outputs_st)
   {
     std::string body(data, headerlen);
 
-    std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> new_outputs;
+    std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::exported_transfer_details>> new_outputs;
     try
     {
       binary_archive<false> ar{epee::strspan<std::uint8_t>(body)};
@@ -13368,9 +13401,9 @@ size_t wallet2::import_outputs_from_str(const std::string &outputs_st)
     }
     catch (...) {}
     if (!loaded)
-      new_outputs.second.clear();
+      std::get<2>(new_outputs).clear();
 
-    std::pair<uint64_t, std::vector<tools::wallet2::transfer_details>> outputs;
+    std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::transfer_details>> outputs;
     if (!loaded) try
     {
       binary_archive<false> ar{epee::strspan<std::uint8_t>(body)};
@@ -13395,11 +13428,12 @@ size_t wallet2::import_outputs_from_str(const std::string &outputs_st)
 
     if (!loaded)
     {
-      outputs.first = 0;
-      outputs.second = {};
+      std::get<0>(outputs) = 0;
+      std::get<1>(outputs) = 0;
+      std::get<2>(outputs) = {};
     }
 
-    imported_outputs = !new_outputs.second.empty() ? import_outputs(new_outputs) : !outputs.second.empty() ? import_outputs(outputs) : 0;
+    imported_outputs = !std::get<2>(new_outputs).empty() ? import_outputs(new_outputs) : !std::get<2>(outputs).empty() ? import_outputs(outputs) : 0;
   }
   catch (const std::exception &e)
   {
diff --git a/src/wallet/wallet2.h b/src/wallet/wallet2.h
index 06d4e636e..e684505f6 100644
--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@@ -63,6 +63,7 @@
 #include "serialization/crypto.h"
 #include "serialization/string.h"
 #include "serialization/pair.h"
+#include "serialization/tuple.h"
 #include "serialization/containers.h"
 
 #include "wallet_errors.h"
@@ -673,16 +674,32 @@ private:
     struct unsigned_tx_set
     {
       std::vector<tx_construction_data> txes;
-      std::pair<size_t, wallet2::transfer_container> transfers;
-      std::pair<size_t, std::vector<wallet2::exported_transfer_details>> new_transfers;
+      std::tuple<uint64_t, uint64_t, wallet2::transfer_container> transfers;
+      std::tuple<uint64_t, uint64_t, std::vector<wallet2::exported_transfer_details>> new_transfers;
 
       BEGIN_SERIALIZE_OBJECT()
-        VERSION_FIELD(1)
+        VERSION_FIELD(2)
         FIELD(txes)
-        if (version >= 1)
-          FIELD(new_transfers)
-        else
-          FIELD(transfers)
+        if (version == 0)
+        {
+          std::pair<size_t, wallet2::transfer_container> v0_transfers;
+          FIELD(v0_transfers);
+          std::get<0>(transfers) = std::get<0>(v0_transfers);
+          std::get<1>(transfers) = std::get<0>(v0_transfers) + std::get<1>(v0_transfers).size();
+          std::get<2>(transfers) = std::get<1>(v0_transfers);
+          return true;
+        }
+        if (version == 1)
+        {
+          std::pair<size_t, std::vector<wallet2::exported_transfer_details>> v1_transfers;
+          FIELD(v1_transfers);
+          std::get<0>(new_transfers) = std::get<0>(v1_transfers);
+          std::get<1>(new_transfers) = std::get<0>(v1_transfers) + std::get<1>(v1_transfers).size();
+          std::get<2>(new_transfers) = std::get<1>(v1_transfers);
+          return true;
+        }
+
+        FIELD(new_transfers)
       END_SERIALIZE()
     };
 
@@ -1453,10 +1470,10 @@ private:
     bool verify_with_public_key(const std::string &data, const crypto::public_key &public_key, const std::string &signature) const;
 
     // Import/Export wallet data
-    std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> export_outputs(bool all = false) const;
-    std::string export_outputs_to_str(bool all = false) const;
-    size_t import_outputs(const std::pair<uint64_t, std::vector<tools::wallet2::exported_transfer_details>> &outputs);
-    size_t import_outputs(const std::pair<uint64_t, std::vector<tools::wallet2::transfer_details>> &outputs);
+    std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::exported_transfer_details>> export_outputs(bool all = false, uint32_t start = 0, uint32_t count = 0xffffffff) const;
+    std::string export_outputs_to_str(bool all = false, uint32_t start = 0, uint32_t count = 0) const;
+    size_t import_outputs(const std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::exported_transfer_details>> &outputs);
+    size_t import_outputs(const std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::transfer_details>> &outputs);
     size_t import_outputs_from_str(const std::string &outputs_st);
     payment_container export_payments() const;
     void import_payments(const payment_container &payments);
@@ -1904,7 +1921,7 @@ BOOST_CLASS_VERSION(tools::wallet2::unconfirmed_transfer_details, 8)
 BOOST_CLASS_VERSION(tools::wallet2::confirmed_transfer_details, 6)
 BOOST_CLASS_VERSION(tools::wallet2::address_book_row, 18)
 BOOST_CLASS_VERSION(tools::wallet2::reserve_proof_entry, 0)
-BOOST_CLASS_VERSION(tools::wallet2::unsigned_tx_set, 0)
+BOOST_CLASS_VERSION(tools::wallet2::unsigned_tx_set, 1)
 BOOST_CLASS_VERSION(tools::wallet2::signed_tx_set, 1)
 BOOST_CLASS_VERSION(tools::wallet2::tx_construction_data, 4)
 BOOST_CLASS_VERSION(tools::wallet2::pending_tx, 3)
@@ -1914,6 +1931,17 @@ namespace boost
 {
   namespace serialization
   {
+    template<class Archive, class F, class S, class T>
+    inline void serialize(
+        Archive & ar,
+        std::tuple<F, S, T> & t,
+        const unsigned int /* file_version */
+    ){
+        ar & boost::serialization::make_nvp("f", std::get<0>(t));
+        ar & boost::serialization::make_nvp("s", std::get<1>(t));
+        ar & boost::serialization::make_nvp("t", std::get<2>(t));
+    }
+
     template <class Archive>
     inline typename std::enable_if<!Archive::is_loading::value, void>::type initialize_transfer_details(Archive &a, tools::wallet2::transfer_details &x, const boost::serialization::version_type ver)
     {
@@ -2274,7 +2302,17 @@ namespace boost
     inline void serialize(Archive &a, tools::wallet2::unsigned_tx_set &x, const boost::serialization::version_type ver)
     {
       a & x.txes;
-      a & x.transfers;
+      if (ver == 0)
+      {
+        // load old version
+        std::pair<size_t, tools::wallet2::transfer_container> old_transfers;
+        a & old_transfers;
+        std::get<0>(x.transfers) = std::get<0>(old_transfers);
+        std::get<1>(x.transfers) = std::get<0>(old_transfers) + std::get<1>(old_transfers).size();
+        std::get<2>(x.transfers) = std::get<1>(old_transfers);
+        return;
+      }
+      throw std::runtime_error("Boost serialization not supported for newest unsigned_tx_set");
     }
 
     template <class Archive>
diff --git a/src/wallet/wallet_rpc_server.cpp b/src/wallet/wallet_rpc_server.cpp
index 7ec5fc7a1..1f0a1371f 100644
--- a/src/wallet/wallet_rpc_server.cpp
+++ b/src/wallet/wallet_rpc_server.cpp
@@ -2792,7 +2792,7 @@ namespace tools
 
     try
     {
-      res.outputs_data_hex = epee::string_tools::buff_to_hex_nodelimer(m_wallet->export_outputs_to_str(req.all));
+      res.outputs_data_hex = epee::string_tools::buff_to_hex_nodelimer(m_wallet->export_outputs_to_str(req.all, req.start, req.count));
     }
     catch (const std::exception &e)
     {
diff --git a/src/wallet/wallet_rpc_server_commands_defs.h b/src/wallet/wallet_rpc_server_commands_defs.h
index ecfc8e673..2cca323ee 100644
--- a/src/wallet/wallet_rpc_server_commands_defs.h
+++ b/src/wallet/wallet_rpc_server_commands_defs.h
@@ -1785,9 +1785,13 @@ namespace wallet_rpc
     struct request_t
     {
       bool all;
+      uint32_t start;
+      uint32_t count;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(all)
+        KV_SERIALIZE_OPT(start, 0u)
+        KV_SERIALIZE_OPT(count, 0xffffffffu)
       END_KV_SERIALIZE_MAP()
     };
     typedef epee::misc_utils::struct_init<request_t> request;
diff --git a/tests/data/fuzz/cold-outputs/out-all-6 b/tests/data/fuzz/cold-outputs/out-all-6
index d24fc604f..8016928e3 100644
--- a/tests/data/fuzz/cold-outputs/out-all-6
+++ b/tests/data/fuzz/cold-outputs/out-all-6
diff --git a/tests/functional_tests/cold_signing.py b/tests/functional_tests/cold_signing.py
index 9f8143a8c..983cd9029 100755
--- a/tests/functional_tests/cold_signing.py
+++ b/tests/functional_tests/cold_signing.py
@@ -34,6 +34,7 @@
 from __future__ import print_function
 from framework.daemon import Daemon
 from framework.wallet import Wallet
+import random
 
 SEED = 'velvet lymph giddy number token physics poetry unquoted nibs useful sabotage limits benches lifestyle eden nitrogen anvil fewest avoid batch vials washing fences goat unquoted'
 STANDARD_ADDRESS = '42ey1afDFnn4886T7196doS9GPMzexD9gXpsZJDwVjeRVdFCSoHnv7KPbBeGpzJBzHRCAs9UxqeoyFQMYbqSWYTfJJQAWDm'
@@ -44,8 +45,10 @@ class ColdSigningTest():
         self.reset()
         self.create(0)
         self.mine()
-        self.transfer()
-        self.self_transfer_to_subaddress()
+        for piecemeal_output_export in [False, True]:
+            self.transfer(piecemeal_output_export)
+        for piecemeal_output_export in [False, True]:
+            self.self_transfer_to_subaddress(piecemeal_output_export)
         self.transfer_after_empty_export_import()
 
     def reset(self):
@@ -93,19 +96,42 @@ class ColdSigningTest():
         daemon.generateblocks(STANDARD_ADDRESS, 80)
         wallet.refresh()
 
-    def export_import(self):
+    def export_import(self, piecemeal_output_export):
         self.hot_wallet.refresh()
-        res = self.hot_wallet.export_outputs()
-        self.cold_wallet.import_outputs(res.outputs_data_hex)
+
+        if piecemeal_output_export:
+            res = self.hot_wallet.incoming_transfers()
+            num_outputs = len(res.transfers)
+            done = [False] * num_outputs
+            while len([x for x in done if not done[x]]) > 0:
+                start = int(random.random() * num_outputs)
+                if start == num_outputs:
+                    num_outputs -= 1
+                count = 1 + int(random.random() * 5)
+                res = self.hot_wallet.export_outputs(all = True, start = start, count = count)
+                try:
+                    self.cold_wallet.import_outputs(res.outputs_data_hex)
+                except Exception as e:
+                    # this just means we selected later outputs first, without filling
+                    # new outputs first
+                    if 'Imported outputs omit more outputs that we know of' not in str(e):
+                        raise
+                for i in range(start, start + count):
+                    if i < len(done):
+                        done[i] = True
+        else:
+            res = self.hot_wallet.export_outputs()
+            self.cold_wallet.import_outputs(res.outputs_data_hex)
+
         res = self.cold_wallet.export_key_images(True)
         self.hot_wallet.import_key_images(res.signed_key_images, offset = res.offset)
 
-    def create_tx(self, destination_addr):
+    def create_tx(self, destination_addr, piecemeal_output_export):
         daemon = Daemon()
 
         dst = {'address': destination_addr, 'amount': 1000000000000}
 
-        self.export_import()
+        self.export_import(piecemeal_output_export)
 
         res = self.hot_wallet.transfer([dst], ring_size = 16, get_tx_key = False)
         assert len(res.tx_hash) == 32*2
@@ -166,11 +192,11 @@ class ColdSigningTest():
         res = self.cold_wallet.get_tx_key(txid)
         assert len(res.tx_key) == 64
 
-        self.export_import()
+        self.export_import(piecemeal_output_export)
 
-    def transfer(self):
+    def transfer(self, piecemeal_output_export):
         print("Creating transaction in hot wallet")
-        self.create_tx(STANDARD_ADDRESS)
+        self.create_tx(STANDARD_ADDRESS, piecemeal_output_export)
 
         res = self.cold_wallet.get_address()
         assert len(res['addresses']) == 1
@@ -182,9 +208,9 @@ class ColdSigningTest():
         assert res['addresses'][0].address == STANDARD_ADDRESS
         assert res['addresses'][0].used
 
-    def self_transfer_to_subaddress(self):
+    def self_transfer_to_subaddress(self, piecemeal_output_export):
         print("Self-spending to subaddress in hot wallet")
-        self.create_tx(SUBADDRESS)
+        self.create_tx(SUBADDRESS, piecemeal_output_export)
 
         res = self.cold_wallet.get_address()
         assert len(res['addresses']) == 2
@@ -203,9 +229,9 @@ class ColdSigningTest():
     def transfer_after_empty_export_import(self):
         print("Creating transaction in hot wallet after empty export & import")
         start_len = len(self.hot_wallet.get_transfers()['in'])
-        self.export_import()
+        self.export_import(False)
         assert start_len == len(self.hot_wallet.get_transfers()['in'])
-        self.create_tx(STANDARD_ADDRESS)
+        self.create_tx(STANDARD_ADDRESS, False)
         assert start_len == len(self.hot_wallet.get_transfers()['in']) - 1
 
 class Guard:
diff --git a/tests/fuzz/cold-outputs.cpp b/tests/fuzz/cold-outputs.cpp
index a7e8a6530..fddd5359b 100644
--- a/tests/fuzz/cold-outputs.cpp
+++ b/tests/fuzz/cold-outputs.cpp
@@ -50,7 +50,7 @@ BEGIN_INIT_SIMPLE_FUZZER()
 END_INIT_SIMPLE_FUZZER()
 
 BEGIN_SIMPLE_FUZZER()
-  std::pair<uint64_t, std::vector<tools::wallet2::transfer_details>> outputs;
+  std::tuple<uint64_t, uint64_t, std::vector<tools::wallet2::transfer_details>> outputs;
   binary_archive<false> ar{{buf, len}};
   ::serialization::serialize(ar, outputs);
   size_t n_outputs = wallet->import_outputs(outputs);
diff --git a/utils/python-rpc/framework/wallet.py b/utils/python-rpc/framework/wallet.py
index 01e937627..f2618b0a8 100644
--- a/utils/python-rpc/framework/wallet.py
+++ b/utils/python-rpc/framework/wallet.py
@@ -763,10 +763,13 @@ class Wallet(object):
         }
         return self.rpc.send_json_rpc_request(get_languages)
 
-    def export_outputs(self):
+    def export_outputs(self, all = False, start = 0, count = 0xffffffff):
         export_outputs = {
             'method': 'export_outputs',
             'params': {
+                'all': all,
+                'start': start,
+                'count': count,
             },
             'jsonrpc': '2.0', 
             'id': '0'