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Diffstat (limited to '')
| -rw-r--r-- | daemon/signals.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/daemon/signals.c b/daemon/signals.c new file mode 100644 index 00000000..4f225433 --- /dev/null +++ b/daemon/signals.c @@ -0,0 +1,253 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "common.h" + +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, sizeof(buffer) - 1, "\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) + netdata_log_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) { + netdata_log_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; + + // 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; + default: + sa.sa_handler = signal_handler; + break; + } + + if(sigaction(signals_waiting[i].signo, &sa, NULL) == -1) + netdata_log_error("SIGNAL: Failed to change signal handler for: %s", signals_waiting[i].name); + } +} + +void signals_restore_SIGCHLD(void) +{ + struct sigaction sa; + + sa.sa_flags = 0; + sigfillset(&sa.sa_mask); + sa.sa_handler = signal_handler; + + if(sigaction(SIGCHLD, &sa, NULL) == -1) + netdata_log_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) + netdata_log_error("SIGNAL: Failed to reset signal handler for: %s", signals_waiting[i].name); + } +} + +// reap_child reaps the child identified by pid. +static void reap_child(pid_t pid) { + siginfo_t i; + + errno = 0; + netdata_log_debug(D_CHILDS, "SIGNAL: reap_child(%d)...", pid); + if (netdata_waitid(P_PID, (id_t)pid, &i, WEXITED|WNOHANG) == -1) { + if (errno != ECHILD) + netdata_log_error("SIGNAL: waitid(%d): failed to wait for child", pid); + else + netdata_log_info("SIGNAL: waitid(%d): failed - it seems the child is already reaped", pid); + return; + } + else if (i.si_pid == 0) { + // Process didn't exit, this shouldn't happen. + netdata_log_error("SIGNAL: waitid(%d): reports pid 0 - child has not exited", pid); + return; + } + + switch (i.si_code) { + case CLD_EXITED: + netdata_log_info("SIGNAL: reap_child(%d) exited with code: %d", pid, i.si_status); + break; + case CLD_KILLED: + netdata_log_info("SIGNAL: reap_child(%d) killed by signal: %d", pid, i.si_status); + break; + case CLD_DUMPED: + netdata_log_info("SIGNAL: reap_child(%d) dumped core by signal: %d", pid, i.si_status); + break; + case CLD_STOPPED: + netdata_log_info("SIGNAL: reap_child(%d) stopped by signal: %d", pid, i.si_status); + break; + case CLD_TRAPPED: + netdata_log_info("SIGNAL: reap_child(%d) trapped by signal: %d", pid, i.si_status); + break; + case CLD_CONTINUED: + netdata_log_info("SIGNAL: reap_child(%d) continued by signal: %d", pid, i.si_status); + break; + default: + netdata_log_info("SIGNAL: reap_child(%d) gave us a SIGCHLD with code %d and status %d.", pid, i.si_code, i.si_status); + break; + } +} + +// reap_children reaps all pending children which are not managed by myp. +static void reap_children() { + siginfo_t i; + + while(1) { + i.si_pid = 0; + if (netdata_waitid(P_ALL, (id_t)0, &i, WEXITED|WNOHANG|WNOWAIT) == -1 || i.si_pid == 0) + // nothing to do + return; + + 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: + nd_log_limits_unlimited(); + netdata_log_info("SIGNAL: Received %s. Reloading HEALTH configuration...", name); + nd_log_limits_reset(); + execute_command(CMD_RELOAD_HEALTH, NULL, NULL); + break; + + case NETDATA_SIGNAL_SAVE_DATABASE: + nd_log_limits_unlimited(); + netdata_log_info("SIGNAL: Received %s. Saving databases...", name); + nd_log_limits_reset(); + execute_command(CMD_SAVE_DATABASE, NULL, NULL); + break; + + case NETDATA_SIGNAL_REOPEN_LOGS: + nd_log_limits_unlimited(); + netdata_log_info("SIGNAL: Received %s. Reopening all log files...", name); + nd_log_limits_reset(); + execute_command(CMD_REOPEN_LOGS, NULL, NULL); + break; + + case NETDATA_SIGNAL_EXIT_CLEANLY: + nd_log_limits_unlimited(); + netdata_log_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: + reap_children(); + break; + + default: + netdata_log_info("SIGNAL: Received %s. No signal handler configured. Ignoring it.", name); + break; + } + } + } + } + } + else + netdata_log_error("SIGNAL: pause() returned but it was not interrupted by a signal."); + } +} |