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+/* Quagga signal handling functions.
+ * Copyright (C) 2004 Paul Jakma,
+ *
+ * This file is part of Quagga.
+ *
+ * Quagga is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * Quagga is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <zebra.h>
+#include <sigevent.h>
+#include <log.h>
+#include <memory.h>
+#include <lib_errors.h>
+
+#ifdef HAVE_UCONTEXT_H
+#ifdef GNU_LINUX
+/* get REG_EIP from ucontext.h */
+#ifndef __USE_GNU
+#define __USE_GNU
+#endif /* __USE_GNU */
+#endif /* GNU_LINUX */
+#include <ucontext.h>
+#endif /* HAVE_UCONTEXT_H */
+
+
+/* master signals descriptor struct */
+static struct frr_sigevent_master_t {
+ struct thread *t;
+
+ struct frr_signal_t *signals;
+ int sigc;
+
+ volatile sig_atomic_t caught;
+} sigmaster;
+
+/* Generic signal handler
+ * Schedules signal event thread
+ */
+static void frr_signal_handler(int signo)
+{
+ int i;
+ struct frr_signal_t *sig;
+
+ for (i = 0; i < sigmaster.sigc; i++) {
+ sig = &(sigmaster.signals[i]);
+
+ if (sig->signal == signo)
+ sig->caught = 1;
+ }
+
+ sigmaster.caught = 1;
+}
+
+/*
+ * Check whether any signals have been received and are pending. This is done
+ * with the application's key signals blocked. The complete set of signals
+ * is returned in 'setp', so the caller can restore them when appropriate.
+ * If there are pending signals, returns 'true', 'false' otherwise.
+ */
+bool frr_sigevent_check(sigset_t *setp)
+{
+ sigset_t blocked;
+ int i;
+ bool ret;
+
+ sigemptyset(setp);
+ sigemptyset(&blocked);
+
+ /* Set up mask of application's signals */
+ for (i = 0; i < sigmaster.sigc; i++)
+ sigaddset(&blocked, sigmaster.signals[i].signal);
+
+ pthread_sigmask(SIG_BLOCK, &blocked, setp);
+
+ /* Now that the application's signals are blocked, test. */
+ ret = (sigmaster.caught != 0);
+
+ return ret;
+}
+
+/* check if signals have been caught and run appropriate handlers */
+int frr_sigevent_process(void)
+{
+ struct frr_signal_t *sig;
+ int i;
+#ifdef SIGEVENT_BLOCK_SIGNALS
+ /* shouldn't need to block signals, but potentially may be needed */
+ sigset_t newmask, oldmask;
+
+ /*
+ * Block most signals, but be careful not to defer SIGTRAP because
+ * doing so breaks gdb, at least on NetBSD 2.0. Avoid asking to
+ * block SIGKILL, just because we shouldn't be able to do so.
+ */
+ sigfillset(&newmask);
+ sigdelset(&newmask, SIGTRAP);
+ sigdelset(&newmask, SIGKILL);
+
+ if ((sigprocmask(SIG_BLOCK, &newmask, &oldmask)) < 0) {
+ flog_err_sys(EC_LIB_SYSTEM_CALL,
+ "frr_signal_timer: couldnt block signals!");
+ return -1;
+ }
+#endif /* SIGEVENT_BLOCK_SIGNALS */
+
+ if (sigmaster.caught > 0) {
+ sigmaster.caught = 0;
+ /* must not read or set sigmaster.caught after here,
+ * race condition with per-sig caught flags if one does
+ */
+
+ for (i = 0; i < sigmaster.sigc; i++) {
+ sig = &(sigmaster.signals[i]);
+
+ if (sig->caught > 0) {
+ sig->caught = 0;
+ if (sig->handler)
+ sig->handler();
+ }
+ }
+ }
+
+#ifdef SIGEVENT_BLOCK_SIGNALS
+ if (sigprocmask(SIG_UNBLOCK, &oldmask, NULL) < 0)
+ return -1;
+#endif /* SIGEVENT_BLOCK_SIGNALS */
+
+ return 0;
+}
+
+#ifdef SIGEVENT_SCHEDULE_THREAD
+/* timer thread to check signals. shouldn't be needed */
+void frr_signal_timer(struct thread *t)
+{
+ struct frr_sigevent_master_t *sigm;
+
+ sigm = THREAD_ARG(t);
+ sigm->t = NULL;
+ thread_add_timer(sigm->t->master, frr_signal_timer, &sigmaster,
+ FRR_SIGNAL_TIMER_INTERVAL, &sigm->t);
+ frr_sigevent_process();
+}
+#endif /* SIGEVENT_SCHEDULE_THREAD */
+
+/* Initialization of signal handles. */
+/* Signal wrapper. */
+static int signal_set(int signo)
+{
+ int ret;
+ struct sigaction sig;
+ struct sigaction osig;
+
+ sig.sa_handler = &frr_signal_handler;
+ sigfillset(&sig.sa_mask);
+ sig.sa_flags = 0;
+ if (signo == SIGALRM) {
+#ifdef SA_INTERRUPT
+ sig.sa_flags |= SA_INTERRUPT; /* SunOS */
+#endif
+ } else {
+#ifdef SA_RESTART
+ sig.sa_flags |= SA_RESTART;
+#endif /* SA_RESTART */
+ }
+
+ ret = sigaction(signo, &sig, &osig);
+ if (ret < 0)
+ return ret;
+ else
+ return 0;
+}
+
+/* XXX This function should be enhanced to support more platforms
+ (it currently works only on Linux/x86). */
+static void *program_counter(void *context)
+{
+#ifdef HAVE_UCONTEXT_H
+#ifdef GNU_LINUX
+/* these are from GNU libc, rather than Linux, strictly speaking */
+#if defined(REG_EIP)
+# define REG_INDEX REG_EIP
+#elif defined(REG_RIP)
+# define REG_INDEX REG_RIP
+#elif defined(__powerpc__)
+# define REG_INDEX 32
+#endif
+#endif /* GNU_LINUX */
+
+#ifdef REG_INDEX
+#ifdef HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS
+# define REGS gregs[REG_INDEX]
+#elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_UC_REGS)
+# define REGS uc_regs->gregs[REG_INDEX]
+#endif /* HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS */
+#endif /* REG_INDEX */
+
+#ifdef REGS
+ if (context)
+ return (void *)(((ucontext_t *)context)->uc_mcontext.REGS);
+#elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_REGS__NIP)
+ /* older Linux / struct pt_regs ? */
+ if (context)
+ return (void *)(((ucontext_t *)context)->uc_mcontext.regs->nip);
+#endif /* REGS */
+
+#endif /* HAVE_UCONTEXT_H */
+ return NULL;
+}
+
+static void __attribute__((noreturn))
+exit_handler(int signo, siginfo_t *siginfo, void *context)
+{
+ void *pc = program_counter(context);
+
+ zlog_signal(signo, "exiting...", siginfo, pc);
+ _exit(128 + signo);
+}
+
+static void __attribute__((noreturn))
+core_handler(int signo, siginfo_t *siginfo, void *context)
+{
+ void *pc = program_counter(context);
+
+ /* make sure we don't hang in here. default for SIGALRM is terminate.
+ * - if we're in backtrace for more than a second, abort. */
+ struct sigaction sa_default = {.sa_handler = SIG_DFL};
+
+ sigaction(SIGALRM, &sa_default, NULL);
+ sigaction(signo, &sa_default, NULL);
+
+ sigset_t sigset;
+
+ sigemptyset(&sigset);
+ sigaddset(&sigset, SIGALRM);
+ sigprocmask(SIG_UNBLOCK, &sigset, NULL);
+
+ alarm(1);
+
+ zlog_signal(signo, "aborting...", siginfo, pc);
+
+ /* dump memory stats on core */
+ log_memstats(stderr, "core_handler");
+
+ zlog_tls_buffer_fini();
+
+ /* give the kernel a chance to generate a coredump */
+ sigaddset(&sigset, signo);
+ sigprocmask(SIG_UNBLOCK, &sigset, NULL);
+ raise(signo);
+
+ /* only chance to end up here is if the default action for signo is
+ * something other than kill or coredump the process
+ */
+ _exit(128 + signo);
+}
+
+static void trap_default_signals(void)
+{
+ static const int core_signals[] = {
+ SIGQUIT, SIGILL, SIGABRT,
+#ifdef SIGEMT
+ SIGEMT,
+#endif
+ SIGFPE, SIGBUS, SIGSEGV,
+#ifdef SIGSYS
+ SIGSYS,
+#endif
+#ifdef SIGXCPU
+ SIGXCPU,
+#endif
+#ifdef SIGXFSZ
+ SIGXFSZ,
+#endif
+ };
+ static const int exit_signals[] = {
+ SIGHUP, SIGINT, SIGALRM, SIGTERM, SIGUSR1, SIGUSR2,
+#ifdef SIGPOLL
+ SIGPOLL,
+#endif
+#ifdef SIGVTALRM
+ SIGVTALRM,
+#endif
+#ifdef SIGSTKFLT
+ SIGSTKFLT,
+#endif
+ };
+ static const int ignore_signals[] = {
+ SIGPIPE,
+ };
+ static const struct {
+ const int *sigs;
+ unsigned int nsigs;
+ void (*handler)(int signo, siginfo_t *info, void *context);
+ } sigmap[] = {
+ {core_signals, array_size(core_signals), core_handler},
+ {exit_signals, array_size(exit_signals), exit_handler},
+ {ignore_signals, array_size(ignore_signals), NULL},
+ };
+ unsigned int i;
+
+ for (i = 0; i < array_size(sigmap); i++) {
+ unsigned int j;
+
+ for (j = 0; j < sigmap[i].nsigs; j++) {
+ struct sigaction oact;
+ if ((sigaction(sigmap[i].sigs[j], NULL, &oact) == 0)
+ && (oact.sa_handler == SIG_DFL)) {
+ struct sigaction act;
+ sigfillset(&act.sa_mask);
+ if (sigmap[i].handler == NULL) {
+ act.sa_handler = SIG_IGN;
+ act.sa_flags = 0;
+ } else {
+ /* Request extra arguments to signal
+ * handler. */
+ act.sa_sigaction = sigmap[i].handler;
+ act.sa_flags = SA_SIGINFO;
+#ifdef SA_RESETHAND
+ /* don't try to print backtraces
+ * recursively */
+ if (sigmap[i].handler == core_handler)
+ act.sa_flags |= SA_RESETHAND;
+#endif
+ }
+ if (sigaction(sigmap[i].sigs[j], &act, NULL)
+ < 0)
+ flog_err(
+ EC_LIB_SYSTEM_CALL,
+ "Unable to set signal handler for signal %d: %s",
+ sigmap[i].sigs[j],
+ safe_strerror(errno));
+ }
+ }
+ }
+}
+
+void signal_init(struct thread_master *m, int sigc,
+ struct frr_signal_t signals[])
+{
+
+ int i = 0;
+ struct frr_signal_t *sig;
+
+ /* First establish some default handlers that can be overridden by
+ the application. */
+ trap_default_signals();
+
+ while (i < sigc) {
+ sig = &signals[i];
+ if (signal_set(sig->signal) < 0)
+ exit(-1);
+ i++;
+ }
+
+ sigmaster.sigc = sigc;
+ sigmaster.signals = signals;
+
+#ifdef SIGEVENT_SCHEDULE_THREAD
+ sigmaster.t = NULL;
+ thread_add_timer(m, frr_signal_timer, &sigmaster,
+ FRR_SIGNAL_TIMER_INTERVAL, &sigmaster.t);
+#endif /* SIGEVENT_SCHEDULE_THREAD */
+}