7 files changed, 90 insertions, 9 deletions
diff --git a/src/blockchain_db/CMakeLists.txt b/src/blockchain_db/CMakeLists.txt
index 0a21e4920..77faade17 100644
--- a/src/blockchain_db/CMakeLists.txt
+++ b/src/blockchain_db/CMakeLists.txt
@@ -1,4 +1,4 @@
-# Copyright (c) 2014-2019, The Monero Project
+# Copyright (c) 2014-2020, The Monero Project
 #
 # All rights reserved.
 #
diff --git a/src/blockchain_db/blockchain_db.cpp b/src/blockchain_db/blockchain_db.cpp
index 01faf43c4..9e977b1b9 100644
--- a/src/blockchain_db/blockchain_db.cpp
+++ b/src/blockchain_db/blockchain_db.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 // 
 // All rights reserved.
 // 
diff --git a/src/blockchain_db/blockchain_db.h b/src/blockchain_db/blockchain_db.h
index 3e2387da4..f513651ed 100644
--- a/src/blockchain_db/blockchain_db.h
+++ b/src/blockchain_db/blockchain_db.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 //
 // All rights reserved.
 //
@@ -1039,6 +1039,16 @@ public:
   virtual difficulty_type get_block_difficulty(const uint64_t& height) const = 0;
 
   /**
+   * @brief correct blocks cumulative difficulties that were incorrectly calculated due to the 'difficulty drift' bug
+   *
+   * If the block does not exist, the subclass should throw BLOCK_DNE
+   *
+   * @param start_height the height where the drift starts
+   * @param new_cumulative_difficulties new cumulative difficulties to be stored
+   */
+  virtual void correct_block_cumulative_difficulties(const uint64_t& start_height, const std::vector<difficulty_type>& new_cumulative_difficulties) = 0;
+
+  /**
    * @brief fetch a block's already generated coins
    *
    * The subclass should return the total coins generated as of the block
diff --git a/src/blockchain_db/lmdb/db_lmdb.cpp b/src/blockchain_db/lmdb/db_lmdb.cpp
index 76671c7b9..6ea55d09d 100644
--- a/src/blockchain_db/lmdb/db_lmdb.cpp
+++ b/src/blockchain_db/lmdb/db_lmdb.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification, are
@@ -25,6 +25,13 @@
 // 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.
 
+#ifndef _WIN32
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#endif
+
 #include "db_lmdb.h"
 
 #include <boost/filesystem.hpp>
@@ -1287,6 +1294,26 @@ BlockchainLMDB::BlockchainLMDB(bool batch_transactions): BlockchainDB()
   m_hardfork = nullptr;
 }
 
+void BlockchainLMDB::check_mmap_support()
+{
+#ifndef _WIN32
+  const boost::filesystem::path mmap_test_file = m_folder / boost::filesystem::unique_path();
+  int mmap_test_fd = ::open(mmap_test_file.string().c_str(), O_RDWR | O_CREAT, 0600);
+  if (mmap_test_fd < 0)
+    throw0(DB_ERROR((std::string("Failed to check for mmap support: open failed: ") + strerror(errno)).c_str()));
+  epee::misc_utils::auto_scope_leave_caller scope_exit_handler = epee::misc_utils::create_scope_leave_handler([mmap_test_fd, &mmap_test_file]() {
+    ::close(mmap_test_fd);
+    boost::filesystem::remove(mmap_test_file.string());
+  });
+  if (write(mmap_test_fd, "mmaptest", 8) != 8)
+    throw0(DB_ERROR((std::string("Failed to check for mmap support: write failed: ") + strerror(errno)).c_str()));
+  void *mmap_res = mmap(NULL, 8, PROT_READ, MAP_SHARED, mmap_test_fd, 0);
+  if (mmap_res == MAP_FAILED)
+    throw0(DB_ERROR("This filesystem does not support mmap: use --data-dir to place the blockchain on a filesystem which does"));
+  munmap(mmap_res, 8);
+#endif
+}
+
 void BlockchainLMDB::open(const std::string& filename, const int db_flags)
 {
   int result;
@@ -1328,6 +1355,8 @@ void BlockchainLMDB::open(const std::string& filename, const int db_flags)
 
   m_folder = filename;
 
+  check_mmap_support();
+
 #ifdef __OpenBSD__
   if ((mdb_flags & MDB_WRITEMAP) == 0) {
     MCLOG_RED(el::Level::Info, "global", "Running on OpenBSD: forcing WRITEMAP");
@@ -2750,6 +2779,44 @@ difficulty_type BlockchainLMDB::get_block_difficulty(const uint64_t& height) con
   return diff1 - diff2;
 }
 
+void BlockchainLMDB::correct_block_cumulative_difficulties(const uint64_t& start_height, const std::vector<difficulty_type>& new_cumulative_difficulties)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  mdb_txn_cursors *m_cursors = &m_wcursors;
+
+  int result = 0;
+  block_wtxn_start();
+  CURSOR(block_info)
+
+  const uint64_t bc_height = height();
+  if (start_height + new_cumulative_difficulties.size() != bc_height)
+  {
+    block_wtxn_abort();
+    throw0(DB_ERROR("Incorrect new_cumulative_difficulties size"));
+  }
+
+  for (uint64_t height = start_height; height < bc_height; ++height)
+  {
+    MDB_val_set(key, height);
+    result = mdb_cursor_get(m_cur_block_info, (MDB_val *)&zerokval, &key, MDB_GET_BOTH);
+    if (result)
+      throw1(BLOCK_DNE(lmdb_error("Failed to get block info: ", result).c_str()));
+
+    mdb_block_info bi = *(mdb_block_info*)key.mv_data;
+    const difficulty_type d = new_cumulative_difficulties[height - start_height];
+    bi.bi_diff_hi = ((d >> 64) & 0xffffffffffffffff).convert_to<uint64_t>();
+    bi.bi_diff_lo = (d & 0xffffffffffffffff).convert_to<uint64_t>();
+
+    MDB_val_set(key2, height);
+    MDB_val_set(val, bi);
+    result = mdb_cursor_put(m_cur_block_info, &key2, &val, MDB_CURRENT);
+    if (result)
+      throw0(DB_ERROR(lmdb_error("Failed to overwrite block info to db transaction: ", result).c_str()));
+  }
+  block_wtxn_stop();
+}
+
 uint64_t BlockchainLMDB::get_block_already_generated_coins(const uint64_t& height) const
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
diff --git a/src/blockchain_db/lmdb/db_lmdb.h b/src/blockchain_db/lmdb/db_lmdb.h
index 6ddeed671..5abb8014f 100644
--- a/src/blockchain_db/lmdb/db_lmdb.h
+++ b/src/blockchain_db/lmdb/db_lmdb.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification, are
@@ -229,6 +229,8 @@ public:
 
   virtual difficulty_type get_block_difficulty(const uint64_t& height) const;
 
+  virtual void correct_block_cumulative_difficulties(const uint64_t& start_height, const std::vector<difficulty_type>& new_cumulative_difficulties);
+
   virtual uint64_t get_block_already_generated_coins(const uint64_t& height) const;
 
   virtual uint64_t get_block_long_term_weight(const uint64_t& height) const;
@@ -356,6 +358,7 @@ public:
   static int compare_string(const MDB_val *a, const MDB_val *b);
 
 private:
+  void check_mmap_support();
   void do_resize(uint64_t size_increase=0);
 
   bool need_resize(uint64_t threshold_size=0) const;
diff --git a/src/blockchain_db/locked_txn.h b/src/blockchain_db/locked_txn.h
index d14631ddb..1834f56fb 100644
--- a/src/blockchain_db/locked_txn.h
+++ b/src/blockchain_db/locked_txn.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 //
 // All rights reserved.
 //
diff --git a/src/blockchain_db/testdb.h b/src/blockchain_db/testdb.h
index 638dd3b37..92911d081 100644
--- a/src/blockchain_db/testdb.h
+++ b/src/blockchain_db/testdb.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2019, The Monero Project
+// Copyright (c) 2014-2020, The Monero Project
 // 
 // All rights reserved.
 // 
@@ -69,8 +69,8 @@ public:
   virtual cryptonote::blobdata get_block_blob(const crypto::hash& h) const override { return cryptonote::blobdata(); }
   virtual bool get_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
   virtual bool get_pruned_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
-  virtual bool get_pruned_tx_blobs_from(const crypto::hash& h, size_t count, std::vector<cryptonote::blobdata> &bd) const { return false; }
-  virtual bool get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const { return false; }
+  virtual bool get_pruned_tx_blobs_from(const crypto::hash& h, size_t count, std::vector<cryptonote::blobdata> &bd) const override { return false; }
+  virtual bool get_blocks_from(uint64_t start_height, size_t min_count, size_t max_count, size_t max_size, std::vector<std::pair<std::pair<cryptonote::blobdata, crypto::hash>, std::vector<std::pair<crypto::hash, cryptonote::blobdata>>>>& blocks, bool pruned, bool skip_coinbase, bool get_miner_tx_hash) const override { return false; }
   virtual bool get_prunable_tx_blob(const crypto::hash& h, cryptonote::blobdata &tx) const override { return false; }
   virtual bool get_prunable_tx_hash(const crypto::hash& tx_hash, crypto::hash &prunable_hash) const override { return false; }
   virtual uint64_t get_block_height(const crypto::hash& h) const override { return 0; }
@@ -82,6 +82,7 @@ public:
   virtual std::vector<uint64_t> get_block_weights(uint64_t start_height, size_t count) const override { return {}; }
   virtual cryptonote::difficulty_type get_block_cumulative_difficulty(const uint64_t& height) const override { return 10; }
   virtual cryptonote::difficulty_type get_block_difficulty(const uint64_t& height) const override { return 0; }
+  virtual void correct_block_cumulative_difficulties(const uint64_t& start_height, const std::vector<difficulty_type>& new_cumulative_difficulties) override {}
   virtual uint64_t get_block_already_generated_coins(const uint64_t& height) const override { return 10000000000; }
   virtual uint64_t get_block_long_term_weight(const uint64_t& height) const override { return 128; }
   virtual std::vector<uint64_t> get_long_term_block_weights(uint64_t start_height, size_t count) const override { return {}; }