c++ - 重定向子进程的输入和输出不起作用

Question

我编写了两个 C++ 应用程序，一个是控制台，另一个是图形用户界面。我希望 gui 应用程序启动控制台应用程序并在其上插入输入并重定向输出和错误并将它们显示在文本框中。

我的代码在按下运行按钮后无法在 gui 应用程序中运行并且不显示输出并且 gui 应用程序似乎卡住了!

这是我的代码:

[控制台部分]:

#include <iostream>
using namespace std;

int main()
{
int pass;
//cout << "welcome message from cpp app ..." << endl;
cout << "please enter pass => ";
cin >> pass;
if (pass==12345)
    cout << "ok!" << endl;
else
    cout << "oops!" << endl;
//system("pause");
return 0;
}

[GUI部分]:

#include <windows.h>
#include <CommCtrl.h>

#define TEXTBOX1 100
#define BUTTON1 101

HWND htbx = nullptr;
HANDLE hChildStd_IN_Rd = nullptr;
HANDLE hChildStd_IN_Wr = nullptr;
HANDLE hChildStd_OUT_Rd = nullptr;
HANDLE hChildStd_OUT_Wr = nullptr;

int MessageLoop();

void ShowError()
{
    LPVOID lpMsgBuf;
    DWORD dw = GetLastError();
    DWORD flags = FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |FORMAT_MESSAGE_IGNORE_INSERTS;
    FormatMessage(flags, nullptr, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), LPWSTR(&lpMsgBuf), 0, nullptr);
    MessageBox(nullptr, LPCWSTR(lpMsgBuf), L"error", MB_OK);
    LocalFree(lpMsgBuf);
}
void WriteToPipe(LPCWSTR Commands2Write) 
{
    DWORD dwWritten;
    bool bSuccess = false;
    bSuccess = WriteFile(hChildStd_IN_Wr, Commands2Write, sizeof(Commands2Write), &dwWritten, nullptr);
    if (!bSuccess)
        ShowError();
    if (!CloseHandle(hChildStd_IN_Wr))
        ShowError();
}
void ReadFromPipe()
{
    DWORD dwRead;
    LPVOID lpDataBuf[4096];

    if (hChildStd_OUT_Rd==INVALID_HANDLE_VALUE)
    {
        MessageBox(0, L"INVALID HANDLE", L"error", MB_OK);
    }

    //bool bSuccess = false;
    /*bSuccess = ReadFile(hChildStd_OUT_Rd, lpDataBuf, 4096, &dwRead, nullptr);
    if (!bSuccess)
        ShowError();*/

    while (ReadFile(hChildStd_OUT_Rd, lpDataBuf, sizeof(lpDataBuf), &dwRead, nullptr))
    {
       SendMessage(htbx, WM_SETTEXT, 0, LPARAM(LPCWSTR(lpDataBuf)));
      // MessageBox(nullptr, LPCWSTR(lpDataBuf), L"Result", MB_OK);
    }
    LocalFree(lpDataBuf);

}
void Run()
{
    bool bSuccess = false;
    PROCESS_INFORMATION PI;
    ZeroMemory(&PI, sizeof(PI));
    STARTUPINFO SI;
    ZeroMemory(&SI, sizeof(SI));
    SI.cb = sizeof(SI);
    SI.dwFlags =  STARTF_USESTDHANDLES;
    //SI.hStdError = hChildStd_OUT_Wr;
    //SI.hStdOutput = hChildStd_OUT_Wr;
    //SI.hStdInput = hChildStd_IN_Rd;
    SI.hStdError = hChildStd_OUT_Rd;
    SI.hStdOutput = hChildStd_OUT_Rd;
    SI.hStdInput = hChildStd_IN_Wr;

    SECURITY_ATTRIBUTES SA;
    SA.nLength = sizeof(SECURITY_ATTRIBUTES);
    SA.bInheritHandle = TRUE;
    SA.lpSecurityDescriptor = nullptr;

    if (!CreatePipe(&hChildStd_OUT_Rd, &hChildStd_OUT_Wr, &SA, 0))
        ShowError();
    if (!SetHandleInformation(hChildStd_OUT_Rd, HANDLE_FLAG_INHERIT, 0))
        ShowError();
    if (!CreatePipe(&hChildStd_IN_Rd, &hChildStd_IN_Wr, &SA, 0))
        ShowError();
    if (!SetHandleInformation(hChildStd_IN_Wr, HANDLE_FLAG_INHERIT, 0))
        ShowError();
    bSuccess = CreateProcess(L"C:\\Windows\\system32\\cmd.exe",
        L" /c C:\\testa.exe", nullptr, nullptr, TRUE, 0, nullptr, nullptr, &SI, &PI);

    if (!bSuccess){ ShowError(); }
            else{CloseHandle(PI.hProcess);CloseHandle(PI.hThread);}

        WriteToPipe(L"12345");
        ReadFromPipe();
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

    switch (Msg)
    {
    case WM_CREATE:
    {
        CreateWindowEx(0, WC_BUTTON, L"Run", WS_VISIBLE | WS_CHILD, 420, 100, 75, 35, hWnd, HMENU(BUTTON1), nullptr, nullptr);
        htbx=CreateWindowEx(0, WC_EDIT, L"", WS_VISIBLE | WS_CHILD | WS_BORDER| ES_MULTILINE, 10, 10, 400, 300, hWnd, HMENU(TEXTBOX1), nullptr, nullptr);
    }
    break;
    case WM_COMMAND:
        {
            switch (LOWORD(wParam))
            {
            case BUTTON1:
                Run();
                break;
            default:
                break;
            }
        }
        break;
    case WM_CLOSE:
        DestroyWindow(hWnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, Msg, wParam, lParam);
    }

    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPreviewInstance, LPSTR lpcmdline, int ncmdshow)
{
    WNDCLASSEX wndexcls;
    wndexcls.lpszClassName = L"win";
    wndexcls.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndexcls.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wndexcls.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndexcls.hbrBackground = (HBRUSH)(COLOR_3DSHADOW + 1);
    wndexcls.lpszMenuName = NULL;
    wndexcls.style = NULL;
    wndexcls.hInstance = hInstance;
    wndexcls.cbSize = sizeof(WNDCLASSEX);
    wndexcls.cbClsExtra = 0;
    wndexcls.cbWndExtra = 0;
    wndexcls.lpfnWndProc = WndProc;
    RegisterClassEx(&wndexcls);
    HWND Win_Handle = CreateWindowEx(0, L"win", L"TestApp", WS_OVERLAPPEDWINDOW, 100, 100, 640, 380, 0, 0, hInstance, 0);
    ShowWindow(Win_Handle, SW_SHOWDEFAULT);
    UpdateWindow(Win_Handle);

    int exitcode;
    exitcode = MessageLoop();
    return exitcode;
}

int MessageLoop()
{
    MSG wnd_msg;
    while (GetMessage(&wnd_msg, NULL, 0, 0)>0)
    {
        TranslateMessage(&wnd_msg);
        DispatchMessage(&wnd_msg);
    }
    return (int)wnd_msg.wParam;
}

更新:

我已经根据 Barmak Shemirani 的回答更新了代码并使用了 ANSI 字符集。但是 writetopipe 部分不起作用，在 readfrompipe 部分中，如果您在 CreateProcessA 中使用“/c dir”而不是“/c C:\consoleapp.exe”作为第二个参数，例如，它只显示第一行输出而不是总产量。为什么会这样？

[更新代码]:

#include <windows.h>
#include <CommCtrl.h>

#define TEXTBOX1 100
#define BUTTON1 101

HWND htbx = nullptr;
HANDLE out_read = NULL;
HANDLE out_write = NULL;
HANDLE in_read = NULL;
HANDLE in_write = NULL;

int MessageLoop();

void ShowError()
{
    LPVOID lpMsgBuf;
    DWORD dw = GetLastError();
    DWORD flags = FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |FORMAT_MESSAGE_IGNORE_INSERTS;
    FormatMessageA(flags, nullptr, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), LPSTR(&lpMsgBuf), 0, nullptr);
    MessageBoxA(nullptr, LPCSTR(lpMsgBuf), "error", MB_OK);
    LocalFree(lpMsgBuf);
}

void WriteToPipe() 
{
    DWORD writecount;
    char bufw[1024]; 
    //memset(bufw, 12345, 5);
    strncpy_s(bufw, "12345", sizeof(bufw));

    if (WriteFile(in_write, bufw, sizeof(bufw), &writecount, NULL))
    {
        if (!writecount)
        {
            ShowError();
        }

    }
    if (!CloseHandle(in_write))
        ShowError();

    LocalFree(bufw);
}
void ReadFromPipe()
{
    DWORD readCount;
    char bufr[1024];
    memset(bufr, 0, sizeof(bufr));
    if (ReadFile(out_read, bufr, sizeof(bufr), &readCount, NULL))
    {
        if (readCount)
        {
            SendMessageA(htbx, EM_SETSEL, WPARAM(-1), LPARAM(-1));
            SendMessageA(htbx, EM_REPLACESEL, 0, LPARAM(bufr));
        }
    }
    if (!CloseHandle(out_read))
        ShowError();

    LocalFree(bufr);
}
DWORD WINAPI run(LPVOID)
{
    PROCESS_INFORMATION pi{};
    STARTUPINFOA si{ sizeof STARTUPINFO };
    si.dwFlags = STARTF_USESTDHANDLES;

    { //set handles

        SECURITY_ATTRIBUTES secAttr;
        secAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
        secAttr.bInheritHandle = TRUE;
        secAttr.lpSecurityDescriptor = nullptr;

        if (!CreatePipe(&out_read, &out_write, &secAttr, 0)) ShowError();
        if (!SetHandleInformation(out_read, HANDLE_FLAG_INHERIT, 0)) ShowError();
        if (!CreatePipe(&in_read, &in_write, &secAttr, 0)) ShowError();
        if (!SetHandleInformation(in_write, HANDLE_FLAG_INHERIT, 0)) ShowError();

        si.hStdOutput = out_write;
        si.hStdError = out_write;
        si.hStdInput = in_read;
        si.dwFlags |= STARTF_USESTDHANDLES;
    }

    if (!CreateProcessA("C:\\Windows\\system32\\cmd.exe",
        "/c C:\\consoleapp.exe", 0, 0, TRUE, 0, 0, 0, &si, &pi))
        ShowError();

    while (pi.hProcess && WaitForSingleObject(pi.hProcess, 25) == WAIT_TIMEOUT)
    {
        if (out_read == INVALID_HANDLE_VALUE)
            ShowError();
        if (in_write == INVALID_HANDLE_VALUE)
            ShowError();

        WriteToPipe();
        ReadFromPipe();
    }

    CloseHandle(pi.hProcess);
    CloseHandle(pi.hThread);

    return 0;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
    switch (Msg)
    {
    case WM_CREATE:
    {
        CreateWindowExA(0, WC_BUTTONA, "Run", WS_VISIBLE | WS_CHILD, 420, 100, 75, 35, hWnd, HMENU(BUTTON1), nullptr, nullptr);
        htbx=CreateWindowExA(0, WC_EDITA, "", WS_VISIBLE | WS_CHILD | WS_BORDER| ES_MULTILINE, 10, 10, 400, 300, hWnd, HMENU(TEXTBOX1), nullptr, nullptr);
    }
    break;
    case WM_COMMAND:
        {
            switch (LOWORD(wParam))
            {
            case BUTTON1:
                //Run();
                CreateThread(NULL, 0, run, 0, 0, NULL);
                break;
            default:
                break;
            }
        }
        break;
    case WM_CLOSE:
        DestroyWindow(hWnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, Msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPreviewInstance, LPSTR lpcmdline, int ncmdshow)
{
    WNDCLASSEXA wndexcls;
    wndexcls.lpszClassName = "win";
    wndexcls.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndexcls.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wndexcls.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndexcls.hbrBackground = (HBRUSH)(COLOR_3DSHADOW + 1);
    wndexcls.lpszMenuName = NULL;
    wndexcls.style = NULL;
    wndexcls.hInstance = hInstance;
    wndexcls.cbSize = sizeof(WNDCLASSEX);
    wndexcls.cbClsExtra = 0;
    wndexcls.cbWndExtra = 0;
    wndexcls.lpfnWndProc = WndProc;
    RegisterClassExA(&wndexcls);
    HWND Win_Handle = CreateWindowExA(0, "win", "TestApp", WS_OVERLAPPEDWINDOW, 100, 100, 640, 380, 0, 0, hInstance, 0);
    ShowWindow(Win_Handle, SW_SHOWDEFAULT);
    UpdateWindow(Win_Handle);
    int exitcode;
    exitcode = MessageLoop();
    return exitcode;
}

int MessageLoop()
{
    MSG wnd_msg;
    while (GetMessage(&wnd_msg, NULL, 0, 0)>0)
    {
        TranslateMessage(&wnd_msg);
        DispatchMessage(&wnd_msg);
    }
    return (int)wnd_msg.wParam;
}

Answer 1

我不确定重定向控制台窗口的输入和输出是否有意义。如果这是出于练习目的，那么我已经展示了一个更简单的示例来重定向控制台的输出。

控制台程序好像是ANSI，而Windows程序是UNICODE。这部分变得困惑，你必须在某些地方使用 ANSI API。

DWORD WINAPI run(LPVOID)
{
    HANDLE out_read = NULL;
    HANDLE out_write = NULL;

    PROCESS_INFORMATION pi{};
    STARTUPINFO si{ sizeof STARTUPINFO };
    si.dwFlags = STARTF_USESTDHANDLES;

    { //set handles

        SECURITY_ATTRIBUTES secAttr;
        secAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
        secAttr.bInheritHandle = TRUE;
        secAttr.lpSecurityDescriptor = nullptr;

        if (!CreatePipe(&out_read, &out_write, &secAttr, 0)) error();
        if (!SetHandleInformation(out_read, HANDLE_FLAG_INHERIT, 0)) error();

        si.hStdOutput = out_write;
        si.dwFlags |= STARTF_USESTDHANDLES;
    }

    if (!CreateProcess(L"consoleProgram.exe", 0, 0, 0, TRUE, 0, 0, 0, &si, &pi))
        error();

    while (pi.hProcess && WaitForSingleObject(pi.hProcess, 25) == WAIT_TIMEOUT)
    {
        if (out_read == INVALID_HANDLE_VALUE)
            break;

        DWORD readCount;
        char buf[1024];
        memset(buf, 0, sizeof buf);
        if (ReadFile(out_read, buf, sizeof(buf), &readCount, NULL))
        {
            if (readCount)
            {
                SendMessageA(hedit, EM_SETSEL, WPARAM(-1), LPARAM(-1));
                SendMessageA(hedit, EM_REPLACESEL, 0, (LPARAM)buf);
            }
        }
    }

    CloseHandle(pi.hProcess);
    CloseHandle(pi.hThread);

    return 0;
}

LRESULT CALLBACK WndProc(...)
{
    ...
    case WM_COMMAND:
        switch (LOWORD(wParam))
            case BUTTON1:
                CreateThread(NULL, 0, run, 0, 0, NULL);
            ...
}