blockchain_db: fix db txn ending too early

The db txn in add_block ending caused the entire overarching
batch txn to stop.
Also add a new guard class so a db txn can be stopped in the
face of exceptions.

Also use a read only db txn in init when the db itself is
read only, and do not save the max tx size in that case.

2 files changed, 21 insertions, 2 deletions

diff --git a/tests/core_tests/chaingen.h b/tests/core_tests/chaingen.h
index f2bcb7787..2ecbdc436 100644
--- a/tests/core_tests/chaingen.h
+++ b/tests/core_tests/chaingen.h
@@ -643,7 +643,15 @@ public:
     log_event("cryptonote::block");
 
     cryptonote::block_verification_context bvc = AUTO_VAL_INIT(bvc);
-    m_c.handle_incoming_block(t_serializable_object_to_blob(b), &b, bvc);
+    cryptonote::blobdata bd = t_serializable_object_to_blob(b);
+    std::vector<cryptonote::block> pblocks;
+    if (m_c.prepare_handle_incoming_blocks(std::vector<cryptonote::block_complete_entry>(1, {bd, {}}), pblocks))
+    {
+      m_c.handle_incoming_block(bd, &b, bvc);
+      m_c.cleanup_handle_incoming_blocks();
+    }
+    else
+      bvc.m_verifivation_failed = true;
     bool r = check_block_verification_context(bvc, m_ev_index, b, m_validator);
     CHECK_AND_NO_ASSERT_MES(r, false, "block verification context check failed");
     return r;
@@ -666,7 +674,14 @@ public:
     log_event("serialized_block");
 
     cryptonote::block_verification_context bvc = AUTO_VAL_INIT(bvc);
-    m_c.handle_incoming_block(sr_block.data, NULL, bvc);
+    std::vector<cryptonote::block> pblocks;
+    if (m_c.prepare_handle_incoming_blocks(std::vector<cryptonote::block_complete_entry>(1, {sr_block.data, {}}), pblocks))
+    {
+      m_c.handle_incoming_block(sr_block.data, NULL, bvc);
+      m_c.cleanup_handle_incoming_blocks();
+    }
+    else
+      bvc.m_verifivation_failed = true;
 
     cryptonote::block blk;
     std::stringstream ss;
diff --git a/tests/unit_tests/blockchain_db.cpp b/tests/unit_tests/blockchain_db.cpp
index 4fbc21ddc..f302d7946 100644
--- a/tests/unit_tests/blockchain_db.cpp
+++ b/tests/unit_tests/blockchain_db.cpp
@@ -271,6 +271,8 @@ TYPED_TEST(BlockchainDBTest, AddBlock)
   this->get_filenames();
   this->init_hard_fork();
 
+  db_wtxn_guard guard(this->m_db);
+
   // adding a block with no parent in the blockchain should throw.
   // note: this shouldn't be possible, but is a good (and cheap) failsafe.
   //
@@ -317,6 +319,8 @@ TYPED_TEST(BlockchainDBTest, RetrieveBlockData)
   this->get_filenames();
   this->init_hard_fork();
 
+  db_wtxn_guard guard(this->m_db);
+
   ASSERT_NO_THROW(this->m_db->add_block(this->m_blocks[0], t_sizes[0], t_sizes[0],  t_diffs[0], t_coins[0], this->m_txs[0]));
 
   ASSERT_EQ(t_sizes[0], this->m_db->get_block_weight(0));