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/*
* Copyright (C) 2017 "IoT.bzh"
* Author José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <setjmp.h>
#include <time.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <execinfo.h>
#include "sig-monitor.h"
#include "verbose.h"
#define SIG_FOR_TIMER SIGVTALRM
/* local handler */
static _Thread_local sigjmp_buf *error_handler;
/* local timers */
static _Thread_local int thread_timer_set;
static _Thread_local timer_t thread_timerid;
/*
* Dumps the current stack
*/
static void dumpstack(int crop)
{
int idx, count;
void *addresses[1000];
char **locations;
count = backtrace(addresses, sizeof addresses / sizeof *addresses);
locations = backtrace_symbols(addresses, count);
if (locations == NULL)
ERROR("can't get the backtrace (returned %d addresses)", count);
else {
for (idx = crop; idx < count; idx++)
ERROR("[BACKTRACE %d/%d] %s", idx - crop + 1, count - crop, locations[idx]);
free(locations);
}
}
/*
* Creates a timer for the current thread
*
* Returns 0 in case of success
*/
static inline int timeout_create()
{
int rc;
struct sigevent sevp;
if (thread_timer_set)
rc = 0;
else {
sevp.sigev_notify = SIGEV_THREAD_ID;
sevp.sigev_signo = SIG_FOR_TIMER;
sevp.sigev_value.sival_ptr = NULL;
#if defined(sigev_notify_thread_id)
sevp.sigev_notify_thread_id = (pid_t)syscall(SYS_gettid);
#else
sevp._sigev_un._tid = (pid_t)syscall(SYS_gettid);
#endif
rc = timer_create(CLOCK_THREAD_CPUTIME_ID, &sevp, &thread_timerid);
thread_timer_set = !rc;
}
return 0;
}
/*
* Arms the alarm in timeout seconds for the current thread
*/
static inline int timeout_arm(int timeout)
{
int rc;
struct itimerspec its;
rc = timeout_create();
if (rc == 0) {
its.it_interval.tv_sec = 0;
its.it_interval.tv_nsec = 0;
its.it_value.tv_sec = timeout;
its.it_value.tv_nsec = 0;
rc = timer_settime(thread_timerid, 0, &its, NULL);
}
return rc;
}
/*
* Disarms the current alarm
*/
static inline void timeout_disarm()
{
if (thread_timer_set)
timeout_arm(0);
}
/*
* Destroy any alarm resource for the current thread
*/
static inline void timeout_delete()
{
if (thread_timer_set) {
timer_delete(thread_timerid);
thread_timer_set = 0;
}
}
/* Handles signals that terminate the process */
static void on_signal_terminate (int signum)
{
ERROR("Terminating signal %d received: %s", signum, strsignal(signum));
if (signum == SIGABRT)
dumpstack(3);
exit(1);
}
/* Handles monitored signals that can be continued */
static void on_signal_error(int signum)
{
sigset_t sigset;
ERROR("ALERT! signal %d received: %s", signum, strsignal(signum));
if (error_handler == NULL && signum == SIG_FOR_TIMER)
return;
dumpstack(3);
// unlock signal to allow a new signal to come
if (error_handler != NULL) {
sigemptyset(&sigset);
sigaddset(&sigset, signum);
sigprocmask(SIG_UNBLOCK, &sigset, 0);
longjmp(*error_handler, signum);
}
ERROR("Unmonitored signal %d received: %s", signum, strsignal(signum));
exit(2);
}
/* install the handlers */
static int install(void (*handler)(int), int *signals)
{
int result = 1;
while(*signals > 0) {
if (signal(*signals, handler) == SIG_ERR) {
ERROR("failed to install signal handler for signal %s", strsignal(*signals));
result = 0;
}
signals++;
}
return result;
}
int sig_monitor_init()
{
static int sigerr[] = { SIG_FOR_TIMER, SIGSEGV, SIGFPE, SIGILL, SIGBUS, 0 };
static int sigterm[] = { SIGINT, SIGABRT, SIGTERM, 0 };
return (install(on_signal_error, sigerr) & install(on_signal_terminate, sigterm)) - 1;
}
int sig_monitor_init_timeouts()
{
return timeout_create();
}
void sig_monitor_clean_timeouts()
{
timeout_delete();
}
void sig_monitor(int timeout, void (*function)(int sig, void*), void *arg)
{
volatile int signum, signum2;
sigjmp_buf jmpbuf, *older;
older = error_handler;
signum = setjmp(jmpbuf);
if (signum == 0) {
error_handler = &jmpbuf;
if (timeout)
timeout_arm(timeout);
function(0, arg);
} else {
signum2 = setjmp(jmpbuf);
if (signum2 == 0)
function(signum, arg);
}
error_handler = older;
if (timeout)
timeout_disarm();
}
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