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-rw-r--r--daemon/signals.c285
1 files changed, 285 insertions, 0 deletions
diff --git a/daemon/signals.c b/daemon/signals.c
new file mode 100644
index 0000000..c857a9b
--- /dev/null
+++ b/daemon/signals.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "common.h"
+
+static int reaper_enabled = 0;
+
+typedef enum signal_action {
+ NETDATA_SIGNAL_END_OF_LIST,
+ NETDATA_SIGNAL_IGNORE,
+ NETDATA_SIGNAL_EXIT_CLEANLY,
+ NETDATA_SIGNAL_SAVE_DATABASE,
+ NETDATA_SIGNAL_REOPEN_LOGS,
+ NETDATA_SIGNAL_RELOAD_HEALTH,
+ NETDATA_SIGNAL_FATAL,
+ NETDATA_SIGNAL_CHILD,
+} SIGNAL_ACTION;
+
+static struct {
+ int signo; // the signal
+ const char *name; // the name of the signal
+ size_t count; // the number of signals received
+ SIGNAL_ACTION action; // the action to take
+} signals_waiting[] = {
+ { SIGPIPE, "SIGPIPE", 0, NETDATA_SIGNAL_IGNORE },
+ { SIGINT , "SIGINT", 0, NETDATA_SIGNAL_EXIT_CLEANLY },
+ { SIGQUIT, "SIGQUIT", 0, NETDATA_SIGNAL_EXIT_CLEANLY },
+ { SIGTERM, "SIGTERM", 0, NETDATA_SIGNAL_EXIT_CLEANLY },
+ { SIGHUP, "SIGHUP", 0, NETDATA_SIGNAL_REOPEN_LOGS },
+ { SIGUSR1, "SIGUSR1", 0, NETDATA_SIGNAL_SAVE_DATABASE },
+ { SIGUSR2, "SIGUSR2", 0, NETDATA_SIGNAL_RELOAD_HEALTH },
+ { SIGBUS, "SIGBUS", 0, NETDATA_SIGNAL_FATAL },
+ { SIGCHLD, "SIGCHLD", 0, NETDATA_SIGNAL_CHILD },
+
+ // terminator
+ { 0, "NONE", 0, NETDATA_SIGNAL_END_OF_LIST }
+};
+
+static void signal_handler(int signo) {
+ // find the entry in the list
+ int i;
+ for(i = 0; signals_waiting[i].action != NETDATA_SIGNAL_END_OF_LIST ; i++) {
+ if(unlikely(signals_waiting[i].signo == signo)) {
+ signals_waiting[i].count++;
+
+ if(signals_waiting[i].action == NETDATA_SIGNAL_FATAL) {
+ char buffer[200 + 1];
+ snprintfz(buffer, 200, "\nSIGNAL HANDLER: received: %s. Oops! This is bad!\n", signals_waiting[i].name);
+ if(write(STDERR_FILENO, buffer, strlen(buffer)) == -1) {
+ // nothing to do - we cannot write but there is no way to complain about it
+ ;
+ }
+ }
+
+ return;
+ }
+ }
+}
+
+void signals_block(void) {
+ sigset_t sigset;
+ sigfillset(&sigset);
+
+ if(pthread_sigmask(SIG_BLOCK, &sigset, NULL) == -1)
+ error("SIGNAL: Could not block signals for threads");
+}
+
+void signals_unblock(void) {
+ sigset_t sigset;
+ sigfillset(&sigset);
+
+ if(pthread_sigmask(SIG_UNBLOCK, &sigset, NULL) == -1) {
+ error("SIGNAL: Could not unblock signals for threads");
+ }
+}
+
+void signals_init(void) {
+ // Catch signals which we want to use
+ struct sigaction sa;
+ sa.sa_flags = 0;
+
+ // Enable process tracking / reaper if running as init (pid == 1).
+ // This prevents zombie processes when running in a container.
+ if (getpid() == 1) {
+ info("SIGNAL: Enabling reaper");
+ netdata_popen_tracking_init();
+ reaper_enabled = 1;
+ } else {
+ info("SIGNAL: Not enabling reaper");
+ }
+
+ // ignore all signals while we run in a signal handler
+ sigfillset(&sa.sa_mask);
+
+ int i;
+ for (i = 0; signals_waiting[i].action != NETDATA_SIGNAL_END_OF_LIST; i++) {
+ switch (signals_waiting[i].action) {
+ case NETDATA_SIGNAL_IGNORE:
+ sa.sa_handler = SIG_IGN;
+ break;
+ case NETDATA_SIGNAL_CHILD:
+ if (reaper_enabled == 0)
+ continue;
+ // FALLTHROUGH
+ default:
+ sa.sa_handler = signal_handler;
+ break;
+ }
+
+ if(sigaction(signals_waiting[i].signo, &sa, NULL) == -1)
+ error("SIGNAL: Failed to change signal handler for: %s", signals_waiting[i].name);
+ }
+}
+
+void signals_restore_SIGCHLD(void)
+{
+ struct sigaction sa;
+
+ if (reaper_enabled == 0)
+ return;
+
+ sa.sa_flags = 0;
+ sigfillset(&sa.sa_mask);
+ sa.sa_handler = signal_handler;
+
+ if(sigaction(SIGCHLD, &sa, NULL) == -1)
+ error("SIGNAL: Failed to change signal handler for: SIGCHLD");
+}
+
+void signals_reset(void) {
+ struct sigaction sa;
+ sigemptyset(&sa.sa_mask);
+ sa.sa_handler = SIG_DFL;
+ sa.sa_flags = 0;
+
+ int i;
+ for (i = 0; signals_waiting[i].action != NETDATA_SIGNAL_END_OF_LIST; i++) {
+ if(sigaction(signals_waiting[i].signo, &sa, NULL) == -1)
+ error("SIGNAL: Failed to reset signal handler for: %s", signals_waiting[i].name);
+ }
+
+ if (reaper_enabled == 1)
+ netdata_popen_tracking_cleanup();
+}
+
+// reap_child reaps the child identified by pid.
+static void reap_child(pid_t pid) {
+ siginfo_t i;
+
+ errno = 0;
+ debug(D_CHILDS, "SIGNAL: Reaping pid: %d...", pid);
+ if (waitid(P_PID, (id_t)pid, &i, WEXITED|WNOHANG) == -1) {
+ if (errno != ECHILD)
+ error("SIGNAL: Failed to wait for: %d", pid);
+ else
+ debug(D_CHILDS, "SIGNAL: Already reaped: %d", pid);
+ return;
+ } else if (i.si_pid == 0) {
+ // Process didn't exit, this shouldn't happen.
+ return;
+ }
+
+ switch (i.si_code) {
+ case CLD_EXITED:
+ debug(D_CHILDS, "SIGNAL: Child %d exited: %d", pid, i.si_status);
+ break;
+ case CLD_KILLED:
+ debug(D_CHILDS, "SIGNAL: Child %d killed by signal: %d", pid, i.si_status);
+ break;
+ case CLD_DUMPED:
+ debug(D_CHILDS, "SIGNAL: Child %d dumped core by signal: %d", pid, i.si_status);
+ break;
+ case CLD_STOPPED:
+ debug(D_CHILDS, "SIGNAL: Child %d stopped by signal: %d", pid, i.si_status);
+ break;
+ case CLD_TRAPPED:
+ debug(D_CHILDS, "SIGNAL: Child %d trapped by signal: %d", pid, i.si_status);
+ break;
+ case CLD_CONTINUED:
+ debug(D_CHILDS, "SIGNAL: Child %d continued by signal: %d", pid, i.si_status);
+ break;
+ default:
+ debug(D_CHILDS, "SIGNAL: Child %d gave us a SIGCHLD with code %d and status %d.", pid, i.si_code, i.si_status);
+ }
+}
+
+// reap_children reaps all pending children which are not managed by myp.
+static void reap_children() {
+ siginfo_t i;
+
+ while (1 == 1) {
+ // Identify which process caused the signal so we can determine
+ // if we need to reap a re-parented process.
+ i.si_pid = 0;
+ if (waitid(P_ALL, (id_t)0, &i, WEXITED|WNOHANG|WNOWAIT) == -1) {
+ if (errno != ECHILD) // This shouldn't happen with WNOHANG but does.
+ error("SIGNAL: Failed to wait");
+ return;
+ } else if (i.si_pid == 0) {
+ // No child exited.
+ return;
+ } else if (netdata_popen_tracking_pid_shoud_be_reaped(i.si_pid) == 0) {
+ // myp managed, sleep for a short time to avoid busy wait while
+ // this is handled by myp.
+ usleep(10000);
+ } else {
+ // Unknown process, likely a re-parented child, reap it.
+ reap_child(i.si_pid);
+ }
+ }
+}
+
+void signals_handle(void) {
+ while(1) {
+
+ // pause() causes the calling process (or thread) to sleep until a signal
+ // is delivered that either terminates the process or causes the invocation
+ // of a signal-catching function.
+ if(pause() == -1 && errno == EINTR) {
+
+ // loop once, but keep looping while signals are coming in
+ // this is needed because a few operations may take some time
+ // so we need to check for new signals before pausing again
+ int found = 1;
+ while(found) {
+ found = 0;
+
+ // execute the actions of the signals
+ int i;
+ for (i = 0; signals_waiting[i].action != NETDATA_SIGNAL_END_OF_LIST; i++) {
+ if (signals_waiting[i].count) {
+ found = 1;
+ signals_waiting[i].count = 0;
+ const char *name = signals_waiting[i].name;
+
+ switch (signals_waiting[i].action) {
+ case NETDATA_SIGNAL_RELOAD_HEALTH:
+ error_log_limit_unlimited();
+ info("SIGNAL: Received %s. Reloading HEALTH configuration...", name);
+ error_log_limit_reset();
+ execute_command(CMD_RELOAD_HEALTH, NULL, NULL);
+ break;
+
+ case NETDATA_SIGNAL_SAVE_DATABASE:
+ error_log_limit_unlimited();
+ info("SIGNAL: Received %s. Saving databases...", name);
+ error_log_limit_reset();
+ execute_command(CMD_SAVE_DATABASE, NULL, NULL);
+ break;
+
+ case NETDATA_SIGNAL_REOPEN_LOGS:
+ error_log_limit_unlimited();
+ info("SIGNAL: Received %s. Reopening all log files...", name);
+ error_log_limit_reset();
+ execute_command(CMD_REOPEN_LOGS, NULL, NULL);
+ break;
+
+ case NETDATA_SIGNAL_EXIT_CLEANLY:
+ error_log_limit_unlimited();
+ info("SIGNAL: Received %s. Cleaning up to exit...", name);
+ commands_exit();
+ netdata_cleanup_and_exit(0);
+ exit(0);
+ break;
+
+ case NETDATA_SIGNAL_FATAL:
+ fatal("SIGNAL: Received %s. netdata now exits.", name);
+ break;
+
+ case NETDATA_SIGNAL_CHILD:
+ debug(D_CHILDS, "SIGNAL: Received %s. Reaping...", name);
+ reap_children();
+ break;
+
+ default:
+ info("SIGNAL: Received %s. No signal handler configured. Ignoring it.", name);
+ break;
+ }
+ }
+ }
+ }
+ }
+ else
+ error("SIGNAL: pause() returned but it was not interrupted by a signal.");
+ }
+}
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