daemon: use evsignal-based signal handling on POSIX systems (#3782)
If signalfd(2) interface is not available (i.e. everywhere except Linux), use evsignal interface to manage signals.
This commit is contained in:
Dmitry Antipov
GitHub
parent
9fb590d3f5
commit
828d008f82
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@ -7,9 +7,9 @@
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#include <errno.h>
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#include <pthread.h>
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#ifdef HAVE_SYS_SIGNALFD_H
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#include <event2/event.h>
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#include <sys/signalfd.h>
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#endif /* signalfd API */
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#include <event2/event.h>
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#include <signal.h>
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#include <stdlib.h> /* abort(), daemon(), exit() */
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#include <fcntl.h> /* open() */
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@ -25,33 +25,17 @@
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#include "daemon.h"
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using namespace std::literals;
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/***
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****
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***/
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static dtr_callbacks const* callbacks = nullptr;
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static void* callback_arg = nullptr;
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#ifdef HAVE_SYS_SIGNALFD_H
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static int sigfd = -1;
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#else
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static int signal_pipe[2];
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#endif /* signalfd API */
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/***
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****
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***/
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static void set_system_error(tr_error** error, int code, std::string_view message)
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{
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tr_error_set(error, code, fmt::format(FMT_STRING("{:s}: {:s} ({:d}"), message, tr_strerror(code), code));
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}
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/***
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****
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***/
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#ifdef HAVE_SYS_SIGNALFD_H
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static int sigfd = -1;
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static void handle_signal(int sig)
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{
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@ -71,8 +55,6 @@ static void handle_signal(int sig)
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}
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}
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#ifdef HAVE_SYS_SIGNALFD_H
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static void handle_signals(evutil_socket_t fd, short /*what*/, void* /*arg*/)
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{
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struct signalfd_siginfo fdsi;
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@ -118,92 +100,42 @@ static bool setup_signals(void* arg)
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return true;
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}
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#else /* no signalfd API */
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#else /* no signalfd API, use evsignal */
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static void send_signal_to_pipe(int sig)
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static void reconfigure(evutil_socket_t /*fd*/, short /*events*/, void* /*arg*/)
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{
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int const old_errno = errno;
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if (write(signal_pipe[1], &sig, sizeof(sig)) == -1)
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{
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abort();
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}
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errno = old_errno;
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callbacks->on_reconfigure(callback_arg);
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}
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static void* signal_handler_thread_main(void* /*arg*/)
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static void stop(evutil_socket_t /*fd*/, short /*events*/, void* /*arg*/)
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{
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int sig;
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while (read(signal_pipe[0], &sig, sizeof(sig)) == sizeof(sig) && sig != 0)
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{
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handle_signal(sig);
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}
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return nullptr;
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callbacks->on_stop(callback_arg);
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}
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static bool create_signal_pipe(tr_error** error)
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static bool setup_signal(struct event_base* base, int sig, void (*callback)(evutil_socket_t, short, void*))
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{
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if (pipe(signal_pipe) == -1)
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struct event* sigev = evsignal_new(base, sig, callback, nullptr);
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if (sigev == nullptr)
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return false;
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if (evsignal_add(sigev, nullptr) < 0)
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{
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set_system_error(error, errno, "pipe() failed");
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event_free(sigev);
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return false;
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}
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return true;
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}
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static void destroy_signal_pipe(void)
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static bool setup_signals(void* arg)
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{
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close(signal_pipe[0]);
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close(signal_pipe[1]);
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struct event_base* base = static_cast<struct event_base*>(arg);
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return (setup_signal(base, SIGHUP, reconfigure) && setup_signal(base, SIGINT, stop) && setup_signal(base, SIGTERM, stop));
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}
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static bool create_signal_handler_thread(pthread_t* thread, tr_error** error)
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{
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if (!create_signal_pipe(error))
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{
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return false;
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}
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if ((errno = pthread_create(thread, nullptr, &signal_handler_thread_main, nullptr)) != 0)
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{
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set_system_error(error, errno, "pthread_create() failed");
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destroy_signal_pipe();
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return false;
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}
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return true;
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}
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static void destroy_signal_handler_thread(pthread_t thread)
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{
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send_signal_to_pipe(0);
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pthread_join(thread, nullptr);
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destroy_signal_pipe();
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}
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static bool setup_signal_handler(int sig, tr_error** error)
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{
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assert(sig != 0);
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if (signal(sig, &send_signal_to_pipe) == SIG_ERR)
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{
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set_system_error(error, errno, "signal() failed");
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return false;
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}
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return true;
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}
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#endif /* signalfd API */
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/***
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****
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***/
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#endif /* HAVE_SYS_SIGNALFD_H */
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bool dtr_daemon(dtr_callbacks const* cb, void* cb_arg, bool foreground, int* exit_code, tr_error** error)
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{
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@ -266,28 +198,7 @@ bool dtr_daemon(dtr_callbacks const* cb, void* cb_arg, bool foreground, int* exi
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#endif
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}
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#ifndef HAVE_SYS_SIGNALFD_H
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pthread_t signal_thread;
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if (!create_signal_handler_thread(&signal_thread, error))
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{
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return false;
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}
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if (!setup_signal_handler(SIGINT, error) || !setup_signal_handler(SIGTERM, error) || !setup_signal_handler(SIGHUP, error))
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{
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destroy_signal_handler_thread(signal_thread);
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return false;
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}
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*exit_code = cb->on_start(cb_arg, nullptr, foreground);
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#else
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*exit_code = cb->on_start(cb_arg, setup_signals, foreground);
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#endif /* signalfd API */
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#ifndef HAVE_SYS_SIGNALFD_H
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destroy_signal_handler_thread(signal_thread);
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#endif /* no signalfd API */
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return true;
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}
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