Question

这是关于Boost.Process 0.5的问题，而不是以后的问题或earlier version，Boost现在包含一个具有不同语法和功能的Boost.Process库。

假设我有一个简单的程序，要求输入一个数字并返回另一个数字，即：

// ask.x,  simple program with IO
#include<iostream>
int main(){
    double n;
    std::cout << "number?" << std::endl;
    std::cin >> n;
    std::cout << n + 1 << std::endl;
}

现在，我希望通过Boost.Process 0.5（http://www.highscore.de/boost/process0.5/boost_process/tutorial.html）与该程序进行交互式编程。当我尝试使用该库时，我没有得到预期的行为，该号码永远不会发送到该程序。（阅读第一行是好的）。我试着写一下http://www.highscore.de/boost/process0.5/boost_process/tutorial.html#boost_process.tutorial.synchronous_i_o中描述的例子的概括，但我失败了。

MWE，上半部分是很多必要的样板，也是我认为我犯错的地方。

#include <boost/process.hpp> // version 0.5
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#include <string>
#define ALSOSEND // for fully interactive case
using namespace boost;
int main() {
    // Boilerplate code, see input only example here https://stackoverflow.com/questions/12329065/how-to-bind-program-termination-with-end-of-stream-in-boost-process-0-5
    process::pipe pi = boost::process::create_pipe();
    process::pipe po = boost::process::create_pipe();
    {
        iostreams::file_descriptor_sink sink(
            pi.sink, 
            iostreams::close_handle
        );
        iostreams::file_descriptor_source source(
            po.source, 
            boost::iostreams::close_handle
        );
        process::execute(
            process::initializers::run_exe("./ask.x"), 
            process::initializers::bind_stdout(sink)
    #ifdef ALSOSEND
            , process::initializers::bind_stdin(source)
    #endif
        );
    }

    iostreams::file_descriptor_source fdsource(pi.source,  iostreams::close_handle);
    iostreams::stream<iostreams::file_descriptor_source> is(fdsource);
    iostreams::file_descriptor_sink fdsink(po.source,  iostreams::close_handle);
    iostreams::stream<iostreams::file_descriptor_sink> os(fdsink);

    // actual interaction with the process
    std::string line;
    std::getline(is, line);
    assert(line == "number?");
    std::cout << "sending: " << "5" << std::endl;
    os << "5" << std::endl; // RUN GETS STUCK HERE
    std::getline(is, line);
    assert(line == "6");
}

显然，我不了解接收器和源的逻辑。我也尝试使用单个pipe作为接收器和源，但它没有用。

如何让程序从已执行的项目读取和写入？

我找不到输入和输出都是交错的例子。

编辑以显示使用早期版本库的工作示例

这是如何在Boost.Process GSOC2010中完成的（不是0.5作为在上面的问题中），注意与实际的互动程序与上面相同。

#include <boost/filesystem.hpp> // quasibug in process GSOC2010 needs to include filesystem BEFORE
#include <boost/process.hpp> // version GSOC2010 (not 0.5)
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#include <string>

using namespace boost;
int main() {
    // boiler plate code
    std::vector<std::string> args;
    process::context ctx;
    ctx.process_name       = "askprocess";
    ctx.streams[process::stdout_id] = boost::process::behavior::pipe();
    ctx.streams[process::stdin_id ] = boost::process::behavior::pipe();

    process::child c = create_child("./ask", args, ctx);
    process::pistream is(c.get_handle(process::stdout_id));
    process::postream os(c.get_handle(process::stdin_id ));

    // actual interaction with the process
    std::string line;
    std::getline(is, line);
    assert(line == "number?");
    std::cout << "sending: " << "5" << std::endl;
    os << "5" << std::endl; // RUN GETS STUCK HERE
    std::getline(is, line);
    assert(line == "6");
}

Answer 1

在以下行中似乎是一个拼写错误：

iostreams::file_descriptor_sink fdsink(po.source,  iostreams::close_handle);

必须：

iostreams::file_descriptor_sink fdsink(po.sink,  iostreams::close_handle);

如何与Boost.Process 0.5中的进程同步交互

1 个答案: