kernel: Add pure kernel bitcoin-chainstate

This showcases a re-implementation of bitcoin-chainstate only using the
kernel C++ API header.

Author: sedited

src/kernel/CMakeLists.txt

@@ -145,3 +145,16 @@ install(TARGETS bitcoinkernel
 
 install(FILES bitcoinkernel.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} COMPONENT Kernel)
 
+add_executable(kernel-bitcoin-chainstate
+    bitcoin-chainstate.cpp
+)
+
+target_link_libraries(kernel-bitcoin-chainstate
+  PRIVATE
+    core_interface
+    bitcoinkernel
+)
+
+set_target_properties(kernel-bitcoin-chainstate PROPERTIES
+  SKIP_BUILD_RPATH OFF
+)

src/kernel/bitcoin-chainstate.cpp

@@ -0,0 +1,197 @@
+#include <kernel/bitcoinkernel_wrapper.h>
+
+#include <cassert>
+#include <filesystem>
+#include <iostream>
+#include <optional>
+#include <sstream>
+
+std::vector<unsigned char> hex_string_to_char_vec(const std::string& hex)
+{
+    std::vector<unsigned char> bytes;
+
+    for (size_t i{0}; i < hex.length(); i += 2) {
+        std::string byteString{hex.substr(i, 2)};
+        unsigned char byte = (char)std::strtol(byteString.c_str(), nullptr, 16);
+        bytes.push_back(byte);
+    }
+
+    return bytes;
+}
+
+class KernelLog
+{
+public:
+    void LogMessage(const char* message)
+    {
+        std::cout << "kernel: " << message;
+    }
+};
+
+class TestValidationInterface : public ValidationInterface<TestValidationInterface>
+{
+public:
+    TestValidationInterface() : ValidationInterface() {}
+
+    std::optional<std::string> m_expected_valid_block = std::nullopt;
+
+    void BlockChecked(const UnownedBlock block, const BlockValidationState state) override
+    {
+        auto mode{state.ValidationMode()};
+        switch (mode) {
+        case kernel_ValidationMode::kernel_VALIDATION_STATE_VALID: {
+            std::cout << "Valid block" << std::endl;
+            return;
+        }
+        case kernel_ValidationMode::kernel_VALIDATION_STATE_INVALID: {
+            std::cout << "Invalid block: ";
+            auto result{state.BlockValidationResult()};
+            switch (result) {
+            case kernel_BlockValidationResult::kernel_BLOCK_RESULT_UNSET:
+                std::cout << "initial value. Block has not yet been rejected" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_HEADER_LOW_WORK:
+                std::cout << "the block header may be on a too-little-work chain" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_CONSENSUS:
+                std::cout << "invalid by consensus rules (excluding any below reasons)" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_CACHED_INVALID:
+                std::cout << "this block was cached as being invalid and we didn't store the reason why" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_INVALID_HEADER:
+                std::cout << "invalid proof of work or time too old" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_MUTATED:
+                std::cout << "the block's data didn't match the data committed to by the PoW" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_MISSING_PREV:
+                std::cout << "We don't have the previous block the checked one is built on" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_INVALID_PREV:
+                std::cout << "A block this one builds on is invalid" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_TIME_FUTURE:
+                std::cout << "block timestamp was > 2 hours in the future (or our clock is bad)" << std::endl;
+                break;
+            case kernel_BlockValidationResult::kernel_BLOCK_CHECKPOINT:
+                std::cout << "the block failed to meet one of our checkpoints" << std::endl;
+                break;
+            }
+            return;
+        }
+        case kernel_ValidationMode::kernel_VALIDATION_STATE_ERROR: {
+            std::cout << "Internal error" << std::endl;
+            return;
+        }
+        }
+    }
+};
+
+class TestKernelNotifications : public KernelNotifications<TestKernelNotifications>
+{
+public:
+    void BlockTipHandler(kernel_SynchronizationState state, kernel_BlockIndex* index) override
+    {
+        std::cout << "Block tip changed" << std::endl;
+    }
+
+    void ProgressHandler(const char* title, int progress_percent, bool resume_possible) override
+    {
+        std::cout << "Made progress: " << title << " " << progress_percent << "%" << std::endl;
+    }
+
+    void WarningSetHandler(kernel_Warning warning, const char* message) override
+    {
+        std::cout << message << std::endl;
+    }
+
+    void WarningUnsetHandler(kernel_Warning warning) override
+    {
+        std::cout << "Warning unset: " << warning << std::endl;
+    }
+
+    void FlushErrorHandler(const char* error) override
+    {
+        std::cout << error << std::endl;
+    }
+
+    void FatalErrorHandler(const char* error) override
+    {
+        std::cout << error << std::endl;
+    }
+};
+
+int main(int argc, char* argv[])
+{
+    // SETUP: Argument parsing and handling
+    if (argc != 2) {
+        std::cerr
+            << "Usage: " << argv[0] << " DATADIR" << std::endl
+            << "Display DATADIR information, and process hex-encoded blocks on standard input." << std::endl
+            << std::endl
+            << "IMPORTANT: THIS EXECUTABLE IS EXPERIMENTAL, FOR TESTING ONLY, AND EXPECTED TO" << std::endl
+            << "           BREAK IN FUTURE VERSIONS. DO NOT USE ON YOUR ACTUAL DATADIR." << std::endl;
+        return 1;
+    }
+    std::filesystem::path abs_datadir{std::filesystem::absolute(argv[1])};
+    std::filesystem::create_directories(abs_datadir);
+
+    kernel_LoggingOptions logging_options = {
+        .log_timestamps = true,
+        .log_time_micros = false,
+        .log_threadnames = false,
+        .log_sourcelocations = false,
+        .always_print_category_levels = true,
+    };
+
+    Logger logger{std::make_unique<KernelLog>(KernelLog{}), logging_options};
+
+    ContextOptions options{};
+    ChainParams params{kernel_ChainType::kernel_CHAIN_TYPE_REGTEST};
+    options.SetChainParams(params);
+
+    TestKernelNotifications notifications{};
+    options.SetNotifications(notifications);
+
+    Context context{options};
+    assert(context);
+
+    ChainstateManagerOptions chainman_opts{context, abs_datadir};
+    assert(chainman_opts);
+    BlockManagerOptions blockman_opts{context, abs_datadir / "blocks"};
+    assert(blockman_opts);
+
+    auto chainman{std::make_unique<ChainMan>(context, chainman_opts, blockman_opts)};
+    assert(chainman);
+
+    ChainstateLoadOptions chainstate_load_opts{};
+    assert(chainman->LoadChainstate(chainstate_load_opts));
+
+    std::cout << "Enter the block you want to validate on the next line:" << std::endl;
+
+    for (std::string line; std::getline(std::cin, line);) {
+        if (line.empty()) {
+            std::cerr << "Empty line found, try again:" << std::endl;
+            continue;
+        }
+
+        auto raw_block{hex_string_to_char_vec(line)};
+        auto block = Block{raw_block};
+        if (!block) {
+            std::cout << "Failed to parse entered block, try again:" << std::endl;
+            continue;
+        }
+
+        bool new_block = false;
+        bool accepted = chainman->ProcessBlock(block, &new_block);
+        if (accepted) {
+            std::cout << "Validated block successfully." << std::endl;
+        } else {
+            std::cout << "Block was not accepted" << std::endl;
+        }
+        if (!new_block) {
+            std::cout << "Block is a duplicate" << std::endl;
+        }
+    }
+}

test/lint/lint-locale-dependence.py

@@ -46,6 +46,7 @@
     "src/test/fuzz/locale.cpp:.*setlocale",
     "src/test/util_tests.cpp:.*strtoll",
     "src/test/kernel/test_kernel.cpp:.*strtol",
+    "src/kernel/bitcoin-chainstate.cpp:.*strtol",
     "src/wallet/bdb.cpp:.*DbEnv::strerror",  # False positive
     "src/util/syserror.cpp:.*strerror",      # Outside this function use `SysErrorString`
 ]

test/lint/test_runner/src/main.rs

@@ -276,6 +276,7 @@ fn lint_std_filesystem() -> LintResult {
             "./src/",
             ":(exclude)src/util/fs.h",
             ":(exclude)src/test/kernel/test_kernel.cpp",
+            ":(exclude)src/kernel/bitcoin-chainstate.cpp",
         ])
         .status()
         .expect("command error")