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node-api,src: fix module registration in MSVC C++
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PR-URL: #42459
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
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vmoroz authored and mhdawson committed Apr 7, 2022
1 parent 646e057 commit 44fdf95
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Showing 6 changed files with 95 additions and 3 deletions.
8 changes: 5 additions & 3 deletions src/node.h
Original file line number Diff line number Diff line change
Expand Up @@ -827,11 +827,13 @@ extern "C" NODE_EXTERN void node_module_register(void* mod);
#endif

#if defined(_MSC_VER)
#pragma section(".CRT$XCU", read)
#define NODE_C_CTOR(fn) \
NODE_CTOR_PREFIX void __cdecl fn(void); \
__declspec(dllexport, allocate(".CRT$XCU")) \
void (__cdecl*fn ## _)(void) = fn; \
namespace { \
struct fn##_ { \
fn##_() { fn(); }; \
} fn##_v_; \
} \
NODE_CTOR_PREFIX void __cdecl fn(void)
#else
#define NODE_C_CTOR(fn) \
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17 changes: 17 additions & 0 deletions src/node_api.h
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Expand Up @@ -44,12 +44,29 @@ typedef struct napi_module {
#define NAPI_MODULE_VERSION 1

#if defined(_MSC_VER)
#if defined(__cplusplus)
#define NAPI_C_CTOR(fn) \
static void __cdecl fn(void); \
namespace { \
struct fn##_ { \
fn##_() { fn(); } \
} fn##_v_; \
} \
static void __cdecl fn(void)
#else // !defined(__cplusplus)
#pragma section(".CRT$XCU", read)
// The NAPI_C_CTOR macro defines a function fn that is called during CRT
// initialization.
// C does not support dynamic initialization of static variables and this code
// simulates C++ behavior. Exporting the function pointer prevents it from being
// optimized. See for details:
// https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-initialization?view=msvc-170
#define NAPI_C_CTOR(fn) \
static void __cdecl fn(void); \
__declspec(dllexport, allocate(".CRT$XCU")) void(__cdecl * fn##_)(void) = \
fn; \
static void __cdecl fn(void)
#endif // defined(__cplusplus)
#else
#define NAPI_C_CTOR(fn) \
static void fn(void) __attribute__((constructor)); \
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3 changes: 3 additions & 0 deletions test/js-native-api/common.h
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,9 @@
#define DECLARE_NODE_API_GETTER(name, func) \
{ (name), NULL, NULL, (func), NULL, NULL, napi_default, NULL }

#define DECLARE_NODE_API_PROPERTY_VALUE(name, value) \
{ (name), NULL, NULL, NULL, NULL, (value), napi_default, NULL }

void add_returned_status(napi_env env,
const char* key,
napi_value object,
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8 changes: 8 additions & 0 deletions test/node-api/test_init_order/binding.gyp
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
{
"targets": [
{
"target_name": "test_init_order",
"sources": [ "test_init_order.cc" ]
}
]
}
10 changes: 10 additions & 0 deletions test/node-api/test_init_order/test.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
'use strict';

// This test verifies that C++ static variable dynamic initialization is called
// correctly and does not interfere with the module initialization.
const common = require('../../common');
const test_init_order = require(`./build/${common.buildType}/test_init_order`);
const assert = require('assert');

assert.strictEqual(test_init_order.cppIntValue, 42);
assert.strictEqual(test_init_order.cppStringValue, '123');
52 changes: 52 additions & 0 deletions test/node-api/test_init_order/test_init_order.cc
Original file line number Diff line number Diff line change
@@ -0,0 +1,52 @@
#include <node_api.h>
#include <memory>
#include <string>
#include "../../js-native-api/common.h"

// This test verifies that use of the NAPI_MODULE in C++ code does not
// interfere with the C++ dynamic static initializers.

namespace {

// This class uses dynamic static initializers for the test.
// In production code developers must avoid dynamic static initializers because
// they affect the start up time. They must prefer static initialization such as
// use of constexpr functions or classes with constexpr constructors. E.g.
// instead of using std::string, it is preferrable to use const char[], or
// constexpr std::string_view starting with C++17, or even constexpr
// std::string starting with C++20.
struct MyClass {
static const std::unique_ptr<int> valueHolder;
static const std::string testString;
};

const std::unique_ptr<int> MyClass::valueHolder =
std::unique_ptr<int>(new int(42));
// NOLINTNEXTLINE(runtime/string)
const std::string MyClass::testString = std::string("123");

} // namespace

EXTERN_C_START
napi_value Init(napi_env env, napi_value exports) {
napi_value cppIntValue, cppStringValue;
NODE_API_CALL(env,
napi_create_int32(env, *MyClass::valueHolder, &cppIntValue));
NODE_API_CALL(
env,
napi_create_string_utf8(
env, MyClass::testString.c_str(), NAPI_AUTO_LENGTH, &cppStringValue));

napi_property_descriptor descriptors[] = {
DECLARE_NODE_API_PROPERTY_VALUE("cppIntValue", cppIntValue),
DECLARE_NODE_API_PROPERTY_VALUE("cppStringValue", cppStringValue)};

NODE_API_CALL(env,
napi_define_properties(
env, exports, std::size(descriptors), descriptors));

return exports;
}
EXTERN_C_END

NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)

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