奇怪的异常抛出 - 分配：不允许操作

问题描述

限时删除！！

我想从做异步读CIN所以我有一块code的

client.h

  ...
提高:: ASIO :: POSIX :: stream_descriptor输入;
提高:: ASIO ::流缓冲input_buffer
 

client.cpp

 客户端::（INT ARGC，字符** argv的，提高:: ASIO :: io_service对象和放大器; io_service对象）
    ：TCP_SOCKET（io_service对象）
    ，UDP_SOCKET（io_service对象）
    ，输入（io_service对象，:: DUP（STDIN_FILENO））
{
    ...
    read_std_input（）;
}无效的客户:: read_std_input（）{
    async_read_until（输入，input_buffer，'\\ n'，
                     提高::绑定（安培;客户:: handle_std_read，为此，
                                 提高:: ASIO ::占位符::错误
                                 提高:: ASIO ::占位符:: bytes_transferred））;
}
 

问题是：当我运行我的客户正常的方式[./client]，然后通过命令输入类似，它就像魅力。
然而，当我通过运行[./client＆LT;测试]它抛出：

Do you have an idea of what the problem might be?Thanks!

解决方案

Boost.Asio's POSIX stream-oriented descriptors explicitly do not support regular files. Hence, if test is a regular file, then ./client < test will result in posix::stream_descriptor::assign() failing when attempting to assign STDIN_FILENO to the stream_descriptor. The documentation states:

Consider passing the contents of the test file to client through a pipe.

$ cat test | ./client

---

Here is a complete example program and demonstration:

#include <iostream>
#include <boost/asio.hpp>

void handle_read(
  const boost::system::error_code& error,
  std::size_t bytes_transferred
)
{
  std::cout << "read " << bytes_transferred << " bytes with "
            << error.message() << std::endl;
}

int main()
{
  boost::asio::io_service io_service;
  boost::asio::posix::stream_descriptor input(io_service);

  // Assign STDIN_FILENO to the stream_descriptor.  It will support
  // pipes, standard input and output, and various devices, but NOT
  // regular files.
  boost::system::error_code error;
  input.assign(STDIN_FILENO, error);
  if (error)
  {
    std::cerr << error.message() << std::endl;
    return -1;
  }

  boost::asio::streambuf input_buffer;
  async_read_until(input, input_buffer, '\n', &handle_read);
  io_service.run();
}

Demonstration

$ ./client
testing standard input
read 23 bytes with Success
$ echo "this is a test" > test
$ ./client < test
Operation not permitted
$ cat test | ./client
read 15 bytes with Success

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