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// Copyright (c) 2022 Klemens D. Morgenstern
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_PROCESS_V2_POSIX_BIND_FD_HPP
#define BOOST_PROCESS_V2_POSIX_BIND_FD_HPP
#include <boost/process/v2/detail/config.hpp>
#include <boost/process/v2/default_launcher.hpp>
#include <fcntl.h>
BOOST_PROCESS_V2_BEGIN_NAMESPACE
namespace posix
{
/// Utility class to bind a file descriptor to an explicit file descriptor for the child process.
struct bind_fd
{
int target;
int fd;
bool fd_needs_closing{false};
~bind_fd()
{
if (fd_needs_closing)
::close(fd);
}
bind_fd() = delete;
/// Inherit file descriptor with the same value.
/**
* This will pass descriptor 42 as 42 to the child process:
* @code
* process p{"test", {}, posix::bind_fd(42)};
* @endcode
*/
bind_fd(int target) : target(target), fd(target) {}
/// Inherit an asio io-object as a given file descriptor to the child process.
/**
* This will pass the tcp::socket, as 42 to the child process:
* @code
* extern tcp::socket sock;
* process p{"test", {}, posix::bind_fd(42, sock)};
* @endcode
*/
template<typename Stream>
bind_fd(int target, Stream && str, decltype(std::declval<Stream>().native_handle()) = -1)
: bind_fd(target, str.native_handle())
{}
/// Inherit a `FILE` as a given file descriptor to the child process.
/**
* This will pass the given `FILE*`, as 42 to the child process:
* @code
* process p{"test", {}, posix::bind_fd(42, stderr)};
* @endcode
*/
bind_fd(int target, FILE * f) : bind_fd(target, fileno(f)) {}
/// Inherit a file descriptor with as a different value.
/**
* This will pass 24 as 42 to the child process:
* @code
* process p{"test", {}, posix::bind_fd(42, 24)};
* @endcode
*/
bind_fd(int target, int fd) : target(target), fd(fd) {}
/// Inherit a null device as a set descriptor.
/**
* This will pass 24 as 42 to the child process:
* @code
* process p{"test", {}, posix::bind_fd(42, nullptr)};
* @endcode
*/
bind_fd(int target, std::nullptr_t) : bind_fd(target, filesystem::path("/dev/null")) {}
/// Inherit a newly opened-file as a set descriptor.
/**
* This will pass 24 as 42 to the child process:
* @code
* process p{"test", {}, posix::bind_fd(42, "extra-output.txt")};
* @endcode
*/
bind_fd(int target, const filesystem::path & pth, int flags = O_RDWR | O_CREAT)
: target(target), fd(::open(pth.c_str(), flags, 0660)), fd_needs_closing(true)
{
}
error_code on_setup(posix::default_launcher & launcher, const filesystem::path &, const char * const *)
{
launcher.fd_whitelist.push_back(target);
return {};
}
/// Implementation of the initialization function.
error_code on_exec_setup(posix::default_launcher & launcher, const filesystem::path &, const char * const *)
{
if (::dup2(fd, target) == -1)
return error_code(errno, system_category());
return error_code ();
}
};
}
BOOST_PROCESS_V2_END_NAMESPACE
#endif //BOOST_PROCESS_V2_POSIX_BIND_FD_HPP
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