ctypes wintypes WCHAR字符串附加空格

一开始我认为这是代码中的一些小问题。在调试时，我发现情况并非如此。从您的示例开始，我开发了另一个示例，说明了一些关键点。

测试.h：

#if !defined(TEST_DLL_H)
#define TEST_DLL_H

#if defined(_WIN32)
#  if defined(TEST_EXPORTS)
#    define TEST_API __declspec(dllexport)
#  else
#    define TEST_API __declspec(dllimport)
#  endif
#  define CALLING_CONVENTION __cdecl
#else
#  define __TEXT(X) L##X
#  define TEXT(X) __TEXT(X)
#  define TEST_API
#  define CALLING_CONVENTION
#endif

namespace TestDll {
typedef struct Simple_ {
wchar_t a[1024];
} Simple;
extern "C" {
TEST_API int CALLING_CONVENTION simple(Simple *pSimple);
TEST_API int CALLING_CONVENTION printStr(char *pStr);
TEST_API int CALLING_CONVENTION wprintWstr(wchar_t *pWstr);
TEST_API wchar_t* CALLING_CONVENTION wstr();
TEST_API void CALLING_CONVENTION clearWstr(wchar_t *pWstr);
}
};
#endif  // TEST_DLL_H

test.cpp：

#define TEST_EXPORTS
#include "test.h"
#if defined(_WIN32)
#  include <Windows.h>
#else
#  include <wchar.h>
#  define __FUNCTION__ "function"
#endif
#include <stdio.h>
//#include <iostream>
#define PRINT_MSG_0() printf("From C: - [%s] (%d) - [%s]n", __FILE__, __LINE__, __FUNCTION__)
#define WPRINT_MSG_0() wprintf(L"From C: - [%s] (%d) - [%s]n", TEXT(__FILE__), __LINE__, TEXT(__FUNCTION__))
#define DUMMY_TEXT_W L"Dummy text."

//using namespace std;

int TestDll::simple(Simple *pSimple) {
//std::wcout << pSimple->a << std::endl;
WPRINT_MSG_0();
int ret = wprintf(L"%s", pSimple->a);
wprintf(L"n");
return ret;
}

int TestDll::printStr(char *pStr) {
PRINT_MSG_0();
int ret = printf("%s", pStr);
printf("n");
return ret;
}

int TestDll::wprintWstr(wchar_t *pWstr) {
WPRINT_MSG_0();
int ret = wprintf(L"%s", pWstr);
wprintf(L"n");
int len = wcslen(pWstr);
char *buf = (char*)pWstr;
wprintf(L"Hex (%d): ", len);
for (int i = 0; i < len * sizeof(wchar_t); i++)
wprintf(L"%02X ", buf[i]);
wprintf(L"n");
return ret;
}

wchar_t *TestDll::wstr() {
wchar_t *ret = (wchar_t*)malloc((wcslen(DUMMY_TEXT_W) + 1) * sizeof(wchar_t));
wcscpy(ret, DUMMY_TEXT_W);
return ret;
}

void TestDll::clearWstr(wchar_t *pWstr) {
free(pWstr);
}

main.cpp：

#include "test.h"
#include <stdio.h>
#if defined(_WIN32)
#  include <Windows.h>
#endif

int main() {
char *text = "Hello, world!";
TestDll::Simple s = { TEXT("Hello, world!") };
int ret = simple(&s);  // ??? Compiles even if namespace not specified here !!!
printf(""simple" returned %dn", ret);
ret = TestDll::printStr("Hello, world!");
printf(""printStr" returned %dn", ret);
ret = TestDll::wprintWstr(s.a);
printf(""wprintWstr" returned %dn", ret);
return 0;
}

code.py:

#!/usr/bin/env python3
import sys
import ctypes

DLL_NMAME = "./test.dll"
DUMMY_TEXT = "Hello, world!"

WCharArr1024 = ctypes.c_wchar * 1024
class SimpleStruct(ctypes.Structure):
_fields_ = [
("a", WCharArr1024),
]

def main():
test_dll = ctypes.CDLL(DLL_NMAME)
simple_func = test_dll.simple
simple_func.argtypes = [ctypes.POINTER(SimpleStruct)]
simple_func.restype = ctypes.c_int
stuct_obj = SimpleStruct(a=DUMMY_TEXT)
print_str_func = test_dll.printStr
print_str_func.argtypes = [ctypes.c_char_p]
print_str_func.restype = ctypes.c_int
wprint_wstr_func = test_dll.wprintWstr
wprint_wstr_func.argtypes = [ctypes.c_wchar_p]
wprint_wstr_func.restype = ctypes.c_int
wstr_func = test_dll.wstr
wstr_func.argtypes = []
wstr_func.restype = ctypes.c_wchar_p
clear_wstr_func = test_dll.clearWstr
clear_wstr_func.argtypes = [ctypes.c_wchar_p]
clear_wstr_func.restype = None
#print("From PY: [{:s}]".format(stuct_obj.a))
ret = simple_func(ctypes.byref(stuct_obj))
print(""{:s}" returned {:d}".format(simple_func.__name__, ret))
ret = print_str_func(DUMMY_TEXT.encode())
print(""{:s}" returned {:d}".format(print_str_func.__name__, ret))
#ret = wprint_wstr_func(ctypes.cast(DUMMY_TEXT.encode(), ctypes.c_wchar_p))
ret = wprint_wstr_func(DUMMY_TEXT)
print(""{:s}" returned {:d}".format(wprint_wstr_func.__name__, ret))
s = wstr_func()
print(""{:s}" returned "{:s}"".format(wstr_func.__name__, s))
#clear_wstr_func(s)

if __name__ == "__main__":
#print("Python {:s} on {:s}n".format(sys.version, sys.platform))
main()

更改：

• 删除了C++层(以排除尽可能多的变量)，仅依赖C
• 将代码调整为符合Nix(我在Ubtu上运行过它，但我遇到了其他不打算讨论的问题)
• 增加了更多的功能(这是一个调试过程)，以收集尽可能多的信息
• 进行了一些重命名、重构和其他不重要的更改
• 在调查过程中，我发现了一个有趣的问题(来自main.cpp)。显然，simple函数会编译，即使我没有准备声明它的命名空间。这不适用于其他函数经过一些快速尝试，我意识到这是因为Simple参数(可能是因为它也是命名空间的一部分？)。无论如何，没有花太多时间，也没有弄清真相，可能是未定义的行为(这只是因为运气不好)
• 窄函数和宽函数是混合的，即NO-NO，仅用于调试/演示目的

输出：

e:WorkDevStackOverflowq054269984>"c:Installx86MicrosoftVisual Studio Community2015vcvcvarsall.bat" x64
e:WorkDevStackOverflowq054269984>dir /b
code.py
main.cpp
test.cpp
test.h
e:WorkDevStackOverflowq054269984>cl /nologo /DDLL /DUNICODE /MD /EHsc test.cpp  /link /NOLOGO /DLL /OUT:test.dll
test.cpp
Creating library test.lib and object test.exp
e:WorkDevStackOverflowq054269984>cl /nologo /DUNICODE /MD /EHsc main.cpp  /link /NOLOGO /OUT:main.exe test.lib
main.cpp
e:WorkDevStackOverflowq054269984>dir /b
code.py
main.cpp
main.exe
main.obj
test.cpp
test.dll
test.exp
test.h
test.lib
test.obj
e:WorkDevStackOverflowq054269984>main.exe
From C: - [test.cpp] (23) - [TestDll::simple]
Hello, world!
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
From C: - [test.cpp] (39) - [TestDll::wprintWstr]
Hello, world!
Hex (13): 48 00 65 00 6C 00 6C 00 6F 00 2C 00 20 00 77 00 6F 00 72 00 6C 00 64 00 21 00
"wprintWstr" returned 13
e:WorkDevStackOverflowq054269984>"e:WorkDevVEnvspy_064_03.06.08_test0Scriptspython.exe" code.py
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32
F r o m   C :   -   [ t e s t . c p p ]   ( 2 3 )   -   [ T e s t D l l : : s i m p l e ]
H e l l o ,   w o r l d !
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
F r o m   C :   -   [ t e s t . c p p ]   ( 3 9 )   -   [ T e s t D l l : : w p r i n t W s t r ]
H e l l o ,   w o r l d !
H e x   ( 1 3 ) :   4 8   0 0   6 5   0 0   6 C   0 0   6 C   0 0   6 F   0 0   2 C   0 0   2 0   0 0   7 7   0 0   6 F   0 0   7 2   0 0   6 C   0 0   6 4   0 0   2 1   0 0
"wprintWstr" returned 13
"wstr" returned "Dummy text."

• 它似乎与Python相关
• 字符串本身没有混乱(它们的长度和wprintf返回值是正确的)。更像是stdout是罪魁祸首

然后，我更进一步：

e:WorkDevStackOverflowq054269984>for /f %f in ('dir /b "e:WorkDevVEnvspy_064*"') do ("e:WorkDevVEnvs%fScriptspython.exe" code.py)
e:WorkDevStackOverflowq054269984>("e:WorkDevVEnvspy_064_02.07.15_test0Scriptspython.exe" code.py )
Python 2.7.15 (v2.7.15:ca079a3ea3, Apr 30 2018, 16:30:26) [MSC v.1500 64 bit (AMD64)] on win32
From C: - [test.cpp] (23) - [TestDll::simple]
Hello, world!
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
From C: - [test.cpp] (39) - [TestDll::wprintWstr]
Hello, world!
Hex (13): 48 00 65 00 6C 00 6C 00 6F 00 2C 00 20 00 77 00 6F 00 72 00 6C 00 64 00 21 00
"wprintWstr" returned 13
"wstr" returned "Dummy text."
e:WorkDevStackOverflowq054269984>("e:WorkDevVEnvspy_064_03.04.04_test0Scriptspython.exe" code.py )
Python 3.4.4 (v3.4.4:737efcadf5a6, Dec 20 2015, 20:20:57) [MSC v.1600 64 bit (AMD64)] on win32
From C: - [test.cpp] (23) - [TestDll::simple]
Hello, world!
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
From C: - [test.cpp] (39) - [TestDll::wprintWstr]
Hello, world!
Hex (13): 48 00 65 00 6C 00 6C 00 6F 00 2C 00 20 00 77 00 6F 00 72 00 6C 00 64 00 21 00
"wprintWstr" returned 13
"wstr" returned "Dummy text."
e:WorkDevStackOverflowq054269984>("e:WorkDevVEnvspy_064_03.05.04_test0Scriptspython.exe" code.py )
Python 3.5.4 (v3.5.4:3f56838, Aug  8 2017, 02:17:05) [MSC v.1900 64 bit (AMD64)] on win32
F r o m   C :   -   [ t e s t . c p p ]   ( 2 3 )   -   [ T e s t D l l : : s i m p l e ]
H e l l o ,   w o r l d !
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
F r o m   C :   -   [ t e s t . c p p ]   ( 3 9 )   -   [ T e s t D l l : : w p r i n t W s t r ]
H e l l o ,   w o r l d !
H e x   ( 1 3 ) :   4 8   0 0   6 5   0 0   6 C   0 0   6 C   0 0   6 F   0 0   2 C   0 0   2 0   0 0   7 7   0 0   6 F   0 0   7 2   0 0   6 C   0 0   6 4   0 0   2 1   0 0
"wprintWstr" returned 13
"wstr" returned "Dummy text."
e:WorkDevStackOverflowq054269984>("e:WorkDevVEnvspy_064_03.06.08_test0Scriptspython.exe" code.py )
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32
F r o m   C :   -   [ t e s t . c p p ]   ( 2 3 )   -   [ T e s t D l l : : s i m p l e ]
H e l l o ,   w o r l d !
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
F r o m   C :   -   [ t e s t . c p p ]   ( 3 9 )   -   [ T e s t D l l : : w p r i n t W s t r ]
H e l l o ,   w o r l d !
H e x   ( 1 3 ) :   4 8   0 0   6 5   0 0   6 C   0 0   6 C   0 0   6 F   0 0   2 C   0 0   2 0   0 0   7 7   0 0   6 F   0 0   7 2   0 0   6 C   0 0   6 4   0 0   2 1   0 0
"wprintWstr" returned 13
"wstr" returned "Dummy text."
e:WorkDevStackOverflowq054269984>("e:WorkDevVEnvspy_064_03.07.02_test0Scriptspython.exe" code.py )
Python 3.7.2 (tags/v3.7.2:9a3ffc0492, Dec 23 2018, 23:09:28) [MSC v.1916 64 bit (AMD64)] on win32
F r o m   C :   -   [ t e s t . c p p ]   ( 2 3 )   -   [ T e s t D l l : : s i m p l e ]
H e l l o ,   w o r l d !
"simple" returned 13
From C: - [test.cpp] (31) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
F r o m   C :   -   [ t e s t . c p p ]   ( 3 9 )   -   [ T e s t D l l : : w p r i n t W s t r ]
H e l l o ,   w o r l d !
H e x   ( 1 3 ) :   4 8   0 0   6 5   0 0   6 C   0 0   6 C   0 0   6 F   0 0   2 C   0 0   2 0   0 0   7 7   0 0   6 F   0 0   7 2   0 0   6 C   0 0   6 4   0 0   2 1   0 0
"wprintWstr" returned 13
"wstr" returned "Dummy text."

如图所示，从Python3.5开始，行为是可复制的。

我认为这是因为[Python]:PEP 529——将Windows文件系统编码更改为UTF-8，但这仅适用于3.6版本。

然后我开始阅读(我甚至试图在Python3.4和Python 3.5之间进行区分)，但没有取得多大成功。我浏览过的一些文章：

• [MSDN]：Windows与C++-使用Printf与现代C++
• [MSDN]：VS2005，控制台，Unicode，wcout失败
• [Python3]：Python 3.5的新增功能

然后我注意到[SO]：在Windows控制台应用程序中输出unicode字符串(@DuckMaestro的答案)，并开始玩[MS.Docs]：_setmode。

添加：

#include <io.h>
#include <fcntl.h>

static int set_stdout_mode(int mode) {
fflush(stdout);
int ret = _setmode(_fileno(stdout), mode);
return ret;
}

并像test.cpp中的int stdout_mode = set_stdout_mode(_O_TEXT);一样调用它，然后从C输出任何内容(和C++：std::wcout行未注释)，得到：

e:WorkDevStackOverflowq054269984>"e:WorkDevVEnvspy_064_03.06.08_test0Scriptspython.exe" code.py
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32
Hello, world!
From C: - [test.cpp] (32) - [TestDll::simple]
Hello, world!
"simple" returned 13
From C: - [test.cpp] (40) - [TestDll::printStr]
Hello, world!
"printStr" returned 13
From C: - [test.cpp] (48) - [TestDll::wprintWstr]
Hello, world!
Hex (13): 48 00 65 00 6C 00 6C 00 6F 00 2C 00 20 00 77 00 6F 00 72 00 6C 00 64 00 21 00
"wprintWstr" returned 13
"wstr" returned "Dummy text."

• 虽然它有效，但我不知道为什么。它可能是未定义的行为
  • 打印_setmode的返回值，显示Python 3.4和main.exe自动将模式设置为_O_TEXT(>0x4000)，而较新的Python版本(不起作用的版本)将其设置为_O_BINARY(0x8000)-这显然是的原因(可能与以下内容有关：[Python]：问题#16587-Py_Initialize在Windows上破坏wprintf)
  • 当调用printf或std::cout时，试图将其设置为任何与宽相关的常量(_O_U16TEXT、_O_U8TEXT)会使程序崩溃(即使在使用宽函数时恢复原始模式-在窄函数之前)
• 尝试输出真实的Unicode字符将不起作用(很可能)
• 您可以在Python端实现相同的目标：msvcrt.setmode(sys.stdout.fileno(), 0x4000)