win32 确保从子进程正确读取所有数据

Question

我想使用 WIN32 API CreateProcess 从另一个 C++ 应用程序启动一个控制台 C++ 应用程序。该子控制台应用程序返回一些结果，我想读取父应用程序中子进程的结果。这是我的代码。

void executeCommand(const std::string& lpCommandLine) 
{
  PROCESS_INFORMATION processInfo;
  STARTUPINFOA startupInfo;
  SECURITY_ATTRIBUTES saAttr;

  HANDLE stdoutReadHandle  = NULL;
  HANDLE stdoutWriteHandle = NULL;

  std::string outbuf;
  DWORD bytes_read;
  char tBuf[257];
  DWORD exitcode;
  BOOL bSuccess = FALSE;

  memset(&saAttr, 0, sizeof(saAttr));
  saAttr.nLength              = sizeof(SECURITY_ATTRIBUTES);
  saAttr.bInheritHandle       = TRUE;
  saAttr.lpSecurityDescriptor = NULL;



 // Create a pipe for the child process's STDOUT.
  if (!CreatePipe(&stdoutReadHandle, &stdoutWriteHandle, &saAttr, 5000))
  {
    return;
  }

  // Ensure the read handle to the pipe for STDOUT is not inherited.
  if (!SetHandleInformation(stdoutReadHandle, HANDLE_FLAG_INHERIT, 0))
  {
    return;
  }

  memset(&startupInfo, 0, sizeof(startupInfo));
  startupInfo.cb          = sizeof(startupInfo);
  startupInfo.hStdError   = stdoutWriteHandle;
  startupInfo.hStdOutput  = stdoutWriteHandle;
  startupInfo.wShowWindow = SW_HIDE;
  startupInfo.hStdInput   = GetStdHandle(STD_INPUT_HANDLE);
  startupInfo.dwFlags |= STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;

  if (!CreateProcessA(NULL, (LPSTR)lpCommandLine.c_str(), NULL, NULL, TRUE, CREATE_NEW_CONSOLE,
                      NULL,
                      0, &startupInfo,
                      &processInfo))
  {
    return;
  }

  CloseHandle(stdoutWriteHandle);

  for (;;)
  {
    bSuccess = ReadFile(stdoutReadHandle, tBuf, 256, &bytes_read, NULL);

    if (!bSuccess || bytes_read == 0)
    {
      break;
    }
    if (bytes_read > 0)
    {
      tBuf[bytes_read] = '\0';
      outbuf += tBuf;
    }
  }

  cmdOutput_ = outbuf;

  if (WaitForSingleObject(processInfo.hProcess, INFINITE) != WAIT_OBJECT_0)
  {
    return;
  }

  if (!GetExitCodeProcess(processInfo.hProcess, &exitcode))
  {
    return;
  }

  CloseHandle(processInfo.hProcess);
  CloseHandle(processInfo.hThread);
}

现在我的问题是，ReadFile 是否有可能立即返回而不读取任何数据，或者不从子进程 stdout 读取完整数据并且仍然返回非零值（这是成功的）？

如果是这样，那么确保读取完整数据并且只有这样我才能继续父进程的最佳方法是什么？