WIRE-420: explain recovery after interrupted chain initialization

libraries/chain/block_log.cpp

@@ -15,6 +15,12 @@ static_assert(__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__);
 
 namespace sysio { namespace chain {
 
+   namespace {
+      constexpr auto empty_active_block_log_message =
+         "{} is empty: the launch that created it did not complete startup. "
+         "Rerun once with --delete-all-blocks.";
+   }
+
    enum versions {
       initial_version = 1,                  ///< complete block log from genesis
       block_x_start_version = 2,            ///< adds optional partial block log, cannot be used for replay without snapshot
@@ -1565,8 +1571,11 @@ namespace sysio { namespace chain {
                                       });
       }
 
-      if (first_block_file.empty() && std::filesystem::exists(block_dir / "blocks.log")) {
-         first_block_file = block_dir / "blocks.log";
+      const auto active_log = block_dir / "blocks.log";
+      if (first_block_file.empty() && std::filesystem::exists(active_log)) {
+         SYS_ASSERT(std::filesystem::file_size(active_log) > 0, block_log_exception,
+                    empty_active_block_log_message, active_log.generic_string());
+         first_block_file = active_log;
       }
 
       if (!first_block_file.empty()) {

libraries/chain/controller.cpp

@@ -51,6 +51,12 @@
 
 namespace sysio::chain {
 
+namespace {
+constexpr auto missing_database_header_message =
+   "State database has no version header: the launch that created it did not complete startup. "
+   "Rerun once with --delete-all-blocks.";
+}
+
 using resource_limits::resource_limits_manager;
 
 using controller_index_set = index_set<
@@ -1481,7 +1487,7 @@ struct controller_impl {
       const auto& header_idx = db.get_index<database_header_multi_index>().indices().get<by_id>();
 
       SYS_ASSERT(header_idx.begin() != header_idx.end(), bad_database_version_exception,
-                 "state database version pre-dates versioning, please restore from a compatible snapshot or replay!");
+                 missing_database_header_message);
 
       auto header_itr = header_idx.begin();
       header_itr->validate();

unittests/block_log_extract.cpp

@@ -4,6 +4,7 @@
 
 #include <sysio/chain/block_log.hpp>
 #include <sysio/chain/block.hpp>
+#include <fstream>
 #include <regex>
 
 using namespace sysio::chain;
@@ -49,6 +50,29 @@ struct block_log_extract_fixture {
 
 BOOST_AUTO_TEST_SUITE(block_log_extraction_tests)
 
+/** An active log created before interrupted startup has no preamble to read. */
+BOOST_AUTO_TEST_CASE(empty_active_log_reports_interrupted_initialization) {
+   fc::temp_directory active_dir;
+   {
+      block_log uninitialized(active_dir.path());
+   }
+   const auto expected = (active_dir.path() / "blocks.log").generic_string() +
+                         " is empty: the launch that created it did not complete startup. "
+                         "Rerun once with --delete-all-blocks.";
+   BOOST_REQUIRE_EXCEPTION(block_log::extract_chain_context(active_dir.path(), {}), block_log_exception,
+                           [&](const auto& ex) { return ex.top_message() == expected; });
+}
+
+BOOST_AUTO_TEST_CASE(empty_retained_log_is_rejected) {
+   fc::temp_directory active_dir;
+   fc::temp_directory retained_dir;
+   {
+      std::ofstream log(retained_dir.path() / "blocks-3-7.log", std::ios::binary);
+   }
+   BOOST_CHECK_THROW(block_log::extract_chain_context(active_dir.path(), retained_dir.path()),
+                     std::ios_base::failure);
+}
+
 BOOST_FIXTURE_TEST_CASE(extract_from_middle, block_log_extract_fixture) try {
 
    fc::temp_directory output_dir;

unittests/restart_chain_tests.cpp

@@ -1,5 +1,5 @@
-#include <sstream>
 #include <fstream>
+#include <sstream>
 
 #include <sysio/chain/block_log.hpp>
 #include <sysio/chain/global_property_object.hpp>
@@ -89,6 +89,36 @@ class replay_tester : public base_tester {
 
 BOOST_AUTO_TEST_SUITE(restart_chain_tests)
 
+/** An interrupted initialization leaves a state database without a version header. */
+BOOST_AUTO_TEST_CASE(interrupted_initialization_reports_missing_database_header) {
+   tester reference;
+   auto cfg = reference.get_config();
+   fc::temp_directory directory;
+   cfg.state_dir = directory.path() / "state";
+   cfg.blocks_dir = directory.path() / "blocks";
+   cfg.finalizers_dir = directory.path() / "finalizers";
+   {
+      controller interrupted(cfg, reference.control->get_chain_id());
+      interrupted.add_indices();
+   }
+   BOOST_REQUIRE_EXCEPTION(controller::extract_chain_id_from_db(cfg.state_dir), bad_database_version_exception,
+                           [](const auto& ex) {
+                              return ex.top_message() ==
+                                     "State database has no version header: the launch that created it did not complete startup. "
+                                     "Rerun once with --delete-all-blocks.";
+                           });
+}
+
+/** A partially written active log still reports its original read failure. */
+BOOST_AUTO_TEST_CASE(restart_rejects_truncated_block_log) {
+   fc::temp_directory directory;
+   {
+      std::ofstream log(directory.path() / "blocks.log", std::ios::binary);
+      log.put('\0');
+   }
+   BOOST_CHECK_THROW(block_log::extract_chain_context(directory.path(), {}), std::ios_base::failure);
+}
+
 /// Existing chain state must never restart with missing, corrupt, unreadable, or mismatched replay protection.
 BOOST_AUTO_TEST_CASE(dedup_state_required_on_restart) {
    for (const std::string damage : {"missing", "corrupt", "unreadable", "mismatched"}) {