如何程序终止绑定尾流中Boost.Process 0.5？ [英] How to bind program termination with end-of-stream in Boost.Process 0.5?

问题描述

在的Boost.Process 0.5这个简单的例子（<一个href=\"http://www.highscore.de/boost/process0.5/index.html\">http://www.highscore.de/boost/process0.5/index.html)一个程序（ LS ）的输出是喂养流。流工作正常，但出乎预期该流不失效（如尾流）程序结束（类似Boost.Process的，如：<一previous版本后， href=\"http://www.highscore.de/boost/process/index.html\">http://www.highscore.de/boost/process/index.html)

我是什么，以便使（示例中的是）流子程序退出后自动失效失踪？

也许是，我在的Boost.Streams 流来设置一个选项类file_descriptor ？

 的#include＆LT;升压/ process.hpp＆GT; // 0.5版本从http://www.highscore.de/boost/process0.5/process.zip
＃包括LT＆;提升/输入输出流/设备/ file_descriptor.hpp＆GT;
＃包括LT＆;升压/输入输出流/ stream.hpp＆GT;
＃包括LT＆;串GT;
使用空间boost ::进程;
使用空间boost ::过程::初始化;
使用空间boost ::输入输出流;
诠释主（）{
    提高::进程::管P = create_pipe（）;
    file_descriptor_sink水槽（p.sink，close_handle）;
    孩子C =执行（run_exe（在/ usr /斌/ LS），bind_stdout（汇））;
    file_descriptor_source源（p.source，close_handle）;
    流＆LT; file_descriptor_source＆GT;是（源）;
    性病::字符串s;
    而（的std ::函数getline（是，S））{
        性病::法院LT＆;＆LT; 读：＆LT;＆LT;小号所述＆;＆下;的std :: ENDL;
    }
    的std ::堵塞＆LT;＆LT; 结束＆LT;＆LT;的std :: ENDL; //永远达不到
}
 

解决方案

我与鲍里斯Schaeling，图书馆的作者的私人（实际上是通过Nabble）通信。丢弃几种可能性，像POSIX /虫子了Boost.Iostreams后，他给我的code，它的工作原理略有修改。基本上，我可以推断的是，类file_descriptor汇必须是超出范围（破坏）为了使流返回EOF。工作code只是增加了对特定范围汇（末尾列出）。我想，这使得很容易封装了所有在 pistream 的类也。 （在我的名单下一步将是允许还输出到过程。）

与升压1.48（Fedora的17）的作品。

 的#include＆LT;升压/ process.hpp＆GT; // 0.5版
＃包括LT＆;提升/输入输出流/设备/ file_descriptor.hpp＆GT;
＃包括LT＆;升压/输入输出流/ stream.hpp＆GT;
＃包括LT＆;串GT;使用空间boost ::进程;
使用空间boost ::过程::初始化;
使用空间boost ::输入输出流;诠释主（）{
    配管p = create_pipe（）;
    {
        //注意，水槽范围
        file_descriptor_sink水槽（p.sink，close_handle）;
        / *子C = * / //没有必要举行一个子对象，它似乎。
        执行（run_exe（在/ usr /斌/ LS），bind_stdout（汇））;
    } //注意，水槽范围    file_descriptor_source源（p.source，close_handle）;
    流＆LT; file_descriptor_source＆GT;是（源）;
    性病::字符串s;
    而（的std ::函数getline（是，S））{
        性病::法院LT＆;＆LT; 读：＆LT;＆LT;小号所述＆;＆下;的std :: ENDL;
    }
    的std ::堵塞＆LT;＆LT; 结束＆LT;＆LT;的std :: ENDL; //永远达不到
}
 

编译与 C（郎）++ -lboost_system -lboost_iostreams

编辑：这似乎是工作为好，这避免了人工范围，但由于片必须是可能会造成混淆临时

  ...
    配管p = create_pipe（）;
    执行（run_exe（在/ usr /斌/ LS），bind_stdout（
        file_descriptor_sink（p.sink，close_handle）
    ））;
    file_descriptor_source源（p.source，close_handle）;
    ...
 

In this simple example of Boost.Process 0.5 ( http://www.highscore.de/boost/process0.5/index.html) the output of a program (ls) is feeding a stream. The stream works fine but contrary to the expectation the stream doesn't become invalid (e.g. end-of-stream) after the program finishes (similar to previous version of Boost.Process, e.g. http://www.highscore.de/boost/process/index.html)

What am I missing in order to make the stream (is in the example) automatically invalid after child program exits?

Perhaps is it an option that I have to set in the Boost.Streams stream of file_descriptor?

#include <boost/process.hpp> // version 0.5 from http://www.highscore.de/boost/process0.5/process.zip
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#include <string>
using namespace boost::process;
using namespace boost::process::initializers;
using namespace boost::iostreams;
int main(){
    boost::process::pipe p = create_pipe();
    file_descriptor_sink sink(p.sink, close_handle);
    child c = execute(run_exe("/usr/bin/ls"), bind_stdout(sink));
    file_descriptor_source source(p.source,  close_handle);
    stream<file_descriptor_source> is(source);
    std::string s;
    while(std::getline(is, s)){
        std::cout << "read: " << s << std::endl;
    }
    std::clog << "end" << std::endl; // never reach
}

解决方案

I had a private (actually through Nabble) communication with Boris Schaeling, the author of the library. After discarding several possibilities, like bugs in posix/boost.iostreams, he gave me a slight modification of the code that works. Basically, what I can deduce is that the file_descriptor sink must be out of scope (destroyed) in order for the stream to return an EOF. The working code simply adds a specific scope for sink (listed at the end). I think this makes easy to encapsulate all in a pistream kind of class. (Next step in my list will be to allow also output to the process.)

Works with Boost 1.48 (Fedora 17).

#include <boost/process.hpp> // version 0.5
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#include <string>

using namespace boost::process;
using namespace boost::process::initializers;
using namespace boost::iostreams;

int main() {
    pipe p = create_pipe();
    {
        // note the scope for sink
        file_descriptor_sink sink(p.sink, close_handle);
        /*  child c = */ // not necessary to hold a child object, it seems.
        execute(run_exe("/usr/bin/ls"), bind_stdout(sink));
    }   // note the scope for sink

    file_descriptor_source source(p.source,  close_handle);
    stream<file_descriptor_source> is(source);
    std::string s;
    while(std::getline(is, s)) {
        std::cout << "read: " << s << std::endl;
    }
    std::clog << "end" << std::endl; // never reach
}

Compiles with c(lang)++ -lboost_system -lboost_iostreams

EDIT: This seems to work as well, which avoid the artificial scope, but can be confusing because the sink has to be a temporary:

    ...
    pipe p = create_pipe();
    execute(run_exe("/usr/bin/ls"), bind_stdout(        
        file_descriptor_sink(p.sink, close_handle)
    ));
    file_descriptor_source source(p.source,  close_handle);
    ...

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