Add evmc::loader library to support dynamic loading

circle.yml

@@ -15,7 +15,8 @@ jobs:
           command: cmake --build ~/build
       - run:
           name: "Unit tests"
-          command: ~/build/test/evmc-test
+          working_directory: ~/build/test
+          command: ./evmc-test
       - run:
           name: "Test"
           command: cmake --build ~/build --target test

include/evmc/loader.h

@@ -0,0 +1,24 @@
+/* EVMC: Ethereum Client-VM Connector API.
+ * Copyright 2018 Pawel Bylica.
+ * Licensed under the MIT License. See the LICENSE file.
+ */
+
+#pragma once
+
+#if __cplusplus
+extern "C" {
+#endif
+
+enum evmc_loader_error_code
+{
+    EVMC_LOADER_SUCCESS = 0,
+    EVMC_LOADER_CANNOT_OPEN,
+    EVMC_LOADER_SYMBOL_NOT_FOUND,
+    EVMC_LOADER_INVALID_ARGUMENT,
+};
+
+struct evmc_instance* evmc_load(const char* filename, enum evmc_loader_error_code* error_code);
+
+#if __cplusplus
+}
+#endif

lib/CMakeLists.txt

@@ -3,3 +3,4 @@
 # Licensed under the MIT License. See the LICENSE file.
 
 add_subdirectory(instructions)
+add_subdirectory(loader)

lib/loader/CMakeLists.txt

@@ -0,0 +1,18 @@
+# EVMC: Ethereum Client-VM Connector API.
+# Copyright 2018 Pawel Bylica.
+# Licensed under the MIT License. See the LICENSE file.
+
+add_library(
+    loader STATIC
+    ${include_dir}/evmc/loader.h
+    loader.c
+)
+
+add_library(evmc::loader ALIAS loader)
+set_target_properties(loader PROPERTIES OUTPUT_NAME evmc-loader)
+target_include_directories(loader PUBLIC $<BUILD_INTERFACE:${include_dir}>$<INSTALL_INTERFACE:include>)
+if(CMAKE_DL_LIBS)
+    target_link_libraries(loader INTERFACE ${CMAKE_DL_LIBS})
+endif()
+
+install(TARGETS loader EXPORT evmcTargets DESTINATION ${CMAKE_INSTALL_LIBDIR})

lib/loader/loader.c

@@ -0,0 +1,94 @@
+/* EVMC: Ethereum Client-VM Connector API.
+ * Copyright 2018 Pawel Bylica.
+ * Licensed under the MIT License. See the LICENSE file.
+ */
+
+#include <evmc/loader.h>
+
+#include <stdint.h>
+#include <string.h>
+
+#include <dlfcn.h>
+
+#define PATH_MAX_LENGTH 4096
+
+#pragma GCC diagnostic ignored "-Wincompatible-pointer-types"
+
+typedef struct evmc_instance* (*evmc_create_fn)();
+
+struct evmc_instance* evmc_load(const char* filename, enum evmc_loader_error_code* error_code)
+{
+    enum evmc_loader_error_code ec = EVMC_LOADER_SUCCESS;
+    struct evmc_instance* instance = NULL;
+
+    if (!filename)
+    {
+        ec = EVMC_LOADER_INVALID_ARGUMENT;
+        goto exit;
+    }
+
+    const size_t length = strlen(filename);
+    if (length == 0 || length > PATH_MAX_LENGTH)
+    {
+        ec = EVMC_LOADER_INVALID_ARGUMENT;
+        goto exit;
+    }
+
+    void* handle = dlopen(filename, RTLD_LAZY);
+    if (!handle)
+    {
+        ec = EVMC_LOADER_CANNOT_OPEN;
+        goto exit;
+    }
+
+    const char prefix[] = "evmc_create_";
+    const size_t prefix_length = strlen(prefix);
+    char name[sizeof(prefix) + PATH_MAX_LENGTH];
+    strcpy(name, prefix);
+
+    const char* sep_pos = strrchr(filename, '/');
+    const char* name_pos = sep_pos ? sep_pos + 1 : filename;
+
+    const char lib_prefix[] = "lib";
+    const size_t lib_prefix_length = strlen(lib_prefix);
+    if (strncmp(name_pos, lib_prefix, lib_prefix_length) == 0)
+        name_pos += lib_prefix_length;
+
+    strncpy(name + prefix_length, name_pos, PATH_MAX_LENGTH);
+
+    char* ext_pos = strrchr(name, '.');
+    if (ext_pos)
+        *ext_pos = 0;
+
+    char* dash_pos = name;
+    while ((dash_pos = strchr(dash_pos, '-')) != NULL)
+        *dash_pos++ = '_';
+
+    const void* symbol = dlsym(handle, name);
+    if (!symbol)
+    {
+        const char* short_name_pos = strrchr(name, '_');
+        if (short_name_pos)
+        {
+            short_name_pos += 1;
+            memmove(name + prefix_length, short_name_pos, strlen(short_name_pos) + 1);
+            symbol = dlsym(handle, name);
+        }
+    }
+
+    if (symbol)
+    {
+        evmc_create_fn create_fn = (evmc_create_fn)(uintptr_t)symbol;
+        instance = create_fn();
+    }
+    else
+    {
+        dlclose(handle);
+        ec = EVMC_LOADER_SYMBOL_NOT_FOUND;
+    }
+
+exit:
+    if (error_code)
+        *error_code = ec;
+    return instance;
+}

test/unittests/CMakeLists.txt

@@ -2,10 +2,34 @@
 # Copyright 2018 Pawel Bylica.
 # Licensed under the MIT License. See the LICENSE file.
 
+add_library(vm-mock SHARED vm_mock.c)
+
+if(UNIX)
+    set(cmd create_symlink)
+else()
+    set(cmd copy)
+endif()
+
+add_custom_command(
+    TARGET vm-mock POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> ${CMAKE_SHARED_LIBRARY_PREFIX}aaa${CMAKE_SHARED_LIBRARY_SUFFIX}
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> double_prefix_aaa.evm
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> double-prefix-aaa.evm
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> eee-bbb.dll
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> ${CMAKE_SHARED_LIBRARY_PREFIX}eee1${CMAKE_SHARED_LIBRARY_SUFFIX}
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> eee2${CMAKE_SHARED_LIBRARY_SUFFIX}
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> ${CMAKE_SHARED_LIBRARY_PREFIX}eee3
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE_NAME:vm-mock> eee4
+    COMMAND ${CMAKE_COMMAND} -E ${cmd} $<TARGET_FILE:vm-mock> ../aaa.evm
+    COMMAND ${CMAKE_COMMAND} -E touch empty.file
+)
+
 add_executable(
     evmc-test
     test_instructions.cpp
+    test_loader.cpp
 )
 
-target_link_libraries(evmc-test PRIVATE instructions GTest::gtest GTest::main)
+target_link_libraries(evmc-test PRIVATE instructions loader GTest::gtest GTest::main)
 set_target_properties(evmc-test PROPERTIES RUNTIME_OUTPUT_DIRECTORY ..)
+add_dependencies(evmc-test vm-mock)

test/unittests/test_loader.cpp

@@ -0,0 +1,176 @@
+// EVMC: Ethereum Client-VM Connector API.
+// Copyright 2018 Pawel Bylica.
+// Licensed under the MIT License. See the LICENSE file.
+
+#include <evmc/loader.h>
+
+#include <gtest/gtest.h>
+
+TEST(loader, nonexistent)
+{
+    evmc_loader_error_code ec;
+    auto x = evmc_load("nonexistent", &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_CANNOT_OPEN);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load("nonexistent", nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, longpath)
+{
+    std::vector<char> path(5000, 'a');
+    *path.rbegin() = 0;
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path.data(), &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_INVALID_ARGUMENT);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path.data(), nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, not_so)
+{
+    auto path = "unittests/empty.file";
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_CANNOT_OPEN);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path, nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, null_path)
+{
+    evmc_loader_error_code ec;
+    auto x = evmc_load(nullptr, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_INVALID_ARGUMENT);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(nullptr, nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, empty_path)
+{
+    evmc_loader_error_code ec;
+    auto x = evmc_load("", &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_INVALID_ARGUMENT);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load("", nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, aaa)
+{
+    auto path = "unittests/libaaa.so";
+
+    evmc_loader_error_code ec;
+    auto x = (uintptr_t)evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SUCCESS);
+    EXPECT_EQ(x, 0xaaa);
+
+    x = (uintptr_t)evmc_load(path, nullptr);
+    EXPECT_EQ(x, 0xaaa);
+}
+
+TEST(loader, prefix_aaa)
+{
+    auto paths = {"unittests/double-prefix-aaa.evm", "unittests/double_prefix_aaa.evm"};
+
+    for (auto& path : paths)
+    {
+        evmc_loader_error_code ec;
+        auto x = (uintptr_t)evmc_load(path, &ec);
+        EXPECT_EQ(ec, EVMC_LOADER_SUCCESS);
+        EXPECT_EQ(x, 0xaaa);
+
+        x = (uintptr_t)evmc_load(path, nullptr);
+        EXPECT_EQ(x, 0xaaa);
+    }
+}
+
+TEST(loader, eee_bbb)
+{
+    auto path = "unittests/eee-bbb.dll";
+
+    evmc_loader_error_code ec;
+    auto x = (uintptr_t)evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SUCCESS);
+    EXPECT_EQ(x, 0xeeebbb);
+
+    x = (uintptr_t)evmc_load(path, nullptr);
+    EXPECT_EQ(x, 0xeeebbb);
+}
+
+TEST(loader, DISABLED_nextto)
+{
+    // FIXME: Does not work because dlopen searches only system paths.
+
+    auto path = "aaa.evm";
+
+    evmc_loader_error_code ec;
+    auto x = (uintptr_t)evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SUCCESS);
+    EXPECT_EQ(x, 0xaaa);
+
+    x = (uintptr_t)evmc_load(path, nullptr);
+    EXPECT_EQ(x, 0xaaa);
+}
+
+TEST(loader, eee1)
+{
+    auto path = "unittests/libeee1.so";
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SYMBOL_NOT_FOUND);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path, nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, eee2)
+{
+    auto path = "unittests/eee2.so";
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SYMBOL_NOT_FOUND);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path, nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, eee3)
+{
+    auto path = "unittests/libeee3";
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SYMBOL_NOT_FOUND);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path, nullptr);
+    EXPECT_EQ(x, nullptr);
+}
+
+TEST(loader, eee4)
+{
+    auto path = "unittests/eee4";
+
+    evmc_loader_error_code ec;
+    auto x = evmc_load(path, &ec);
+    EXPECT_EQ(ec, EVMC_LOADER_SYMBOL_NOT_FOUND);
+    EXPECT_EQ(x, nullptr);
+
+    x = evmc_load(path, nullptr);
+    EXPECT_EQ(x, nullptr);
+}

test/unittests/vm_mock.c

@@ -0,0 +1,14 @@
+/* EVMC: Ethereum Client-VM Connector API.
+ * Copyright 2018 Pawel Bylica.
+ * Licensed under the MIT License. See the LICENSE file.
+ */
+
+void* evmc_create_aaa()
+{
+    return (void*)0xaaa;
+}
+
+void* evmc_create_eee_bbb()
+{
+    return (void*)0xeeebbb;
+}