detail/posix/is_running.hpp

0001 // Copyright (c) 2016 Klemens D. Morgenstern
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_PROCESS_DETAIL_POSIX_IS_RUNNING_HPP
0007 #define BOOST_PROCESS_DETAIL_POSIX_IS_RUNNING_HPP
0008
0009 #include <boost/process/detail/config.hpp>
0010 #include <boost/process/detail/posix/child_handle.hpp>
0011 #include <system_error>
0012 #include <sys/wait.h>
0013
0014 namespace boost { namespace process { namespace detail { namespace posix {
0015
0016 // Use the "stopped" state (WIFSTOPPED) to indicate "not terminated".
0017 // This bit arrangement of status codes is not guaranteed by POSIX, but (according to comments in
0018 // the glibc <bits/waitstatus.h> header) is the same across systems in practice.
0019 constexpr int still_active = 0x017f;
0020 static_assert(WIFSTOPPED(still_active), "Expected still_active to indicate WIFSTOPPED");
0021 static_assert(!WIFEXITED(still_active), "Expected still_active to not indicate WIFEXITED");
0022 static_assert(!WIFSIGNALED(still_active), "Expected still_active to not indicate WIFSIGNALED");
0023 static_assert(!WIFCONTINUED(still_active), "Expected still_active to not indicate WIFCONTINUED");
0024
0025 inline bool is_running(int code)
0026 {
0027     return !WIFEXITED(code) && !WIFSIGNALED(code);
0028 }
0029
0030 inline bool is_running(const child_handle &p, int & exit_code, std::error_code &ec) noexcept
0031 {
0032     int status;
0033     auto ret = ::waitpid(p.pid, &status, WNOHANG);
0034
0035     if (ret == -1)
0036     {
0037         if (errno != ECHILD) //because it no child is running, then this one isn't either, obviously.
0038             ec = ::boost::process::detail::get_last_error();
0039         return false;
0040     }
0041     else if (ret == 0)
0042         return true;
0043     else
0044     {
0045         ec.clear();
0046
0047         if (!is_running(status))
0048             exit_code = status;
0049
0050         return false;
0051     }
0052 }
0053
0054 inline bool is_running(const child_handle &p, int & exit_code)
0055 {
0056     std::error_code ec;
0057     bool b = is_running(p, exit_code, ec);
0058     boost::process::detail::throw_error(ec, "waitpid(2) failed in is_running");
0059     return b;
0060 }
0061
0062 inline int eval_exit_status(int code)
0063 {
0064     if (WIFEXITED(code))
0065     {
0066         return WEXITSTATUS(code);
0067     }
0068     else if (WIFSIGNALED(code))
0069     {
0070         return WTERMSIG(code);
0071     }
0072     else
0073     {
0074         return code;
0075     }
0076 }
0077
0078 }}}}
0079
0080 #endif