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175 lines
5.1 KiB
C++
175 lines
5.1 KiB
C++
/**
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* Copyright (c) 2013, Timothy Stack
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of Timothy Stack nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @file auto_pid.hh
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*/
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#ifndef auto_pid_hh
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#define auto_pid_hh
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#include <cerrno>
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#include <csignal>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include "base/lnav_log.hh"
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#include "base/result.h"
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#include "mapbox/variant.hpp"
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enum class process_state {
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running,
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finished,
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};
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template<process_state ProcState>
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class auto_pid {
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public:
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explicit auto_pid(pid_t child, int status = 0)
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: ap_status(status), ap_child(child)
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{
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}
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auto_pid(const auto_pid& other) = delete;
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auto_pid(auto_pid&& other) noexcept
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: ap_status(other.ap_status), ap_child(std::move(other).release())
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{
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}
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~auto_pid() noexcept { this->reset(); }
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auto_pid& operator=(auto_pid&& other) noexcept
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{
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auto other_status = other.ap_status;
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this->reset(std::move(other).release());
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this->ap_status = other_status;
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return *this;
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}
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auto_pid& operator=(const auto_pid& other) = delete;
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pid_t in() const { return this->ap_child; }
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bool in_child() const
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{
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static_assert(ProcState == process_state::running,
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"this method is only available in the RUNNING state");
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return this->ap_child == 0;
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}
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pid_t release() && { return std::exchange(this->ap_child, -1); }
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int status() const
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{
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static_assert(ProcState == process_state::finished,
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"wait_for_child() must be called first");
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return this->ap_status;
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}
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bool was_normal_exit() const
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{
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static_assert(ProcState == process_state::finished,
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"wait_for_child() must be called first");
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return WIFEXITED(this->ap_status);
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}
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int term_signal() const
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{
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static_assert(ProcState == process_state::finished,
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"wait_for_child() must be called first");
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return WTERMSIG(this->ap_status);
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}
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int exit_status() const
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{
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static_assert(ProcState == process_state::finished,
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"wait_for_child() must be called first");
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return WEXITSTATUS(this->ap_status);
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}
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using poll_result
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= mapbox::util::variant<auto_pid<process_state::running>,
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auto_pid<process_state::finished>>;
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poll_result poll() &&
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{
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if (this->ap_child != -1) {
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auto rc = waitpid(this->ap_child, &this->ap_status, WNOHANG);
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if (rc <= 0) {
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return std::move(*this);
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}
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}
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return auto_pid<process_state::finished>(
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std::exchange(this->ap_child, -1), this->ap_status);
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}
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auto_pid<process_state::finished> wait_for_child(int options = 0) &&
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{
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if (this->ap_child != -1) {
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while ((waitpid(this->ap_child, &this->ap_status, options)) < 0
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&& (errno == EINTR))
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{
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;
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}
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}
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return auto_pid<process_state::finished>(
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std::exchange(this->ap_child, -1), this->ap_status);
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}
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void reset(pid_t child = -1) noexcept
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{
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if (this->ap_child != child) {
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this->ap_status = 0;
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if (ProcState == process_state::running && this->ap_child != -1) {
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log_debug("sending SIGTERM to child: %d", this->ap_child);
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kill(this->ap_child, SIGTERM);
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}
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this->ap_child = child;
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}
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}
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private:
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int ap_status{0};
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pid_t ap_child;
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};
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namespace lnav {
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namespace pid {
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extern bool in_child;
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Result<auto_pid<process_state::running>, std::string> from_fork();
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} // namespace pid
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} // namespace lnav
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#endif
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