dll.c

#include <windows.h>
#include <stdio.h>

void RunWhoamiAndSaveOutput() {
    SECURITY_ATTRIBUTES sa;
    HANDLE hRead, hWrite;
    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    CHAR buffer[4096];
    DWORD bytesRead;
    BOOL bSuccess;

    // Step 1: Set up security attributes
    sa.nLength = sizeof(SECURITY_ATTRIBUTES);
    sa.bInheritHandle = TRUE;
    sa.lpSecurityDescriptor = NULL;

    // Step 2: Create a pipe for the child process's STDOUT
    if (!CreatePipe(&hRead, &hWrite, &sa, 0)) {
        // Handle the error.
        return;
    }

    // Ensure the read handle to the pipe is not inherited
    SetHandleInformation(hRead, HANDLE_FLAG_INHERIT, 0);

    // Step 3: Set up the STARTUPINFO structure
    ZeroMemory(&si, sizeof(STARTUPINFO));
    si.cb = sizeof(STARTUPINFO);
    si.hStdError = hWrite;
    si.hStdOutput = hWrite;
    si.dwFlags |= STARTF_USESTDHANDLES;

    // Step 4: Create the child process
    ZeroMemory(&pi, sizeof(PROCESS_INFORMATION));
    TCHAR cmdLine[] = TEXT("whoami");

    bSuccess = CreateProcess(
        NULL,
        cmdLine,
        NULL,
        NULL,
        TRUE,
        0,
        NULL,
        NULL,
        &si,
        &pi
    );

    // Step 5: Close the write end of the pipe
    CloseHandle(hWrite);

    if (!bSuccess) {
        // Handle the error.
        CloseHandle(hRead);
        return;
    }

    // Step 6: Read the output from the child process
    FILE *outputFile = fopen("output.txt", "w");
    if (!outputFile) {
        // Handle the error.
        CloseHandle(hRead);
        return;
    }

    while (TRUE) {
        bSuccess = ReadFile(hRead, buffer, sizeof(buffer) - 1, &bytesRead, NULL);
        if (!bSuccess || bytesRead == 0) break;

        buffer[bytesRead] = '\0';
        fputs(buffer, outputFile);
    }

    fclose(outputFile);

    // Step 7: Clean up
    WaitForSingleObject(pi.hProcess, INFINITE);

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