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