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Diffstat (limited to 'src/base/auto_pid.hh')
| -rw-r--r-- | src/base/auto_pid.hh | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/src/base/auto_pid.hh b/src/base/auto_pid.hh new file mode 100644 index 0000000..702af1e --- /dev/null +++ b/src/base/auto_pid.hh @@ -0,0 +1,175 @@ +/** + * 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 |