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// Copyright (c) 2017 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_DETAIL_POSIX_SIGCHLD_SERVICE_HPP_
#define BOOST_PROCESS_DETAIL_POSIX_SIGCHLD_SERVICE_HPP_
#include <boost/asio/dispatch.hpp>
#include <boost/asio/post.hpp>
#include <boost/asio/signal_set.hpp>
#include <boost/asio/strand.hpp>
#include <boost/optional.hpp>
#include <signal.h>
#include <functional>
#include <sys/wait.h>
namespace boost { namespace process { namespace detail { namespace posix {
class sigchld_service : public boost::asio::detail::service_base<sigchld_service>
{
boost::asio::strand<boost::asio::io_context::executor_type> _strand{get_io_context().get_executor()};
boost::asio::signal_set _signal_set{get_io_context(), SIGCHLD};
std::vector<std::pair<::pid_t, std::function<void(int, std::error_code)>>> _receivers;
inline void _handle_signal(const boost::system::error_code & ec);
public:
sigchld_service(boost::asio::io_context & io_context)
: boost::asio::detail::service_base<sigchld_service>(io_context)
{
}
template <typename SignalHandler>
BOOST_ASIO_INITFN_RESULT_TYPE(SignalHandler,
void (int, std::error_code))
async_wait(::pid_t pid, SignalHandler && handler)
{
boost::asio::async_completion<
SignalHandler, void(boost::system::error_code)> init{handler};
auto & h = init.completion_handler;
boost::asio::dispatch(
_strand,
[this, pid, h]
{
//check if the child actually is running first
int status;
auto pid_res = ::waitpid(pid, &status, WNOHANG);
if (pid_res < 0)
h(-1, get_last_error());
else if ((pid_res == pid) && (WIFEXITED(status) || WIFSIGNALED(status)))
h(status, {}); //successfully exited already
else //still running
{
if (_receivers.empty())
_signal_set.async_wait(
[this](const boost::system::error_code &ec, int)
{
boost::asio::dispatch(_strand, [this, ec]{this->_handle_signal(ec);});
});
_receivers.emplace_back(pid, h);
}
});
return init.result.get();
}
void shutdown() override
{
_receivers.clear();
}
void cancel()
{
_signal_set.cancel();
}
void cancel(boost::system::error_code & ec)
{
_signal_set.cancel(ec);
}
};
void sigchld_service::_handle_signal(const boost::system::error_code & ec)
{
std::error_code ec_{ec.value(), std::system_category()};
if (ec_)
{
for (auto & r : _receivers)
r.second(-1, ec_);
return;
}
for (auto & r : _receivers) {
int status;
int pid = ::waitpid(r.first, &status, WNOHANG);
if (pid < 0) {
// error (eg: the process no longer exists)
r.second(-1, get_last_error());
r.first = 0; // mark for deletion
} else if (pid == r.first) {
r.second(status, ec_);
r.first = 0; // mark for deletion
}
// otherwise the process is still around
}
_receivers.erase(std::remove_if(_receivers.begin(), _receivers.end(),
[](const std::pair<::pid_t, std::function<void(int, std::error_code)>> & p)
{
return p.first == 0;
}),
_receivers.end());
if (!_receivers.empty())
{
_signal_set.async_wait(
[this](const boost::system::error_code & ec, int)
{
boost::asio::post(_strand, [this, ec]{this->_handle_signal(ec);});
});
}
}
}
}
}
}
#endif
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