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Diffstat (limited to '')
| -rw-r--r-- | lib/sigevent.c | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/lib/sigevent.c b/lib/sigevent.c new file mode 100644 index 0000000..985bede --- /dev/null +++ b/lib/sigevent.c @@ -0,0 +1,375 @@ +/* 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 */ +} |