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#include "signal_handlers.h"
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#define PPID_ALARM_INTERVAL 2 // send SIGALRM every this seconds
static pid_t orig_ppid;
static void signal_handler(int _) {
exit(EXIT_FAILURE);
}
static void check_ppid(void) {
if (getppid() != orig_ppid) {
exit(EXIT_FAILURE);
}
}
static void check_stdout_open(void) {
if (fcntl(STDOUT_FILENO, F_GETFD) < 0) {
exit(EXIT_FAILURE);
}
}
static void alarm_handler(int _) {
check_ppid();
check_stdout_open();
alarm(PPID_ALARM_INTERVAL);
signal(SIGALRM, alarm_handler);
}
static void die(const char *msg) {
fprintf(stderr, "\nFATAL: %s\n", msg);
abort();
}
static void install_signal_handler(int sig, void (*handler)(int)) {
if (signal(sig, handler) == SIG_ERR) {
die("Could not install signal handler");
}
}
void install_signal_handlers(void) {
// check pipe is still connected
check_stdout_open();
// watch getppid() every PPID_ALARM_INTERVAL seconds
orig_ppid = getppid();
if (orig_ppid <= 1) {
die("prematurely zombied");
}
install_signal_handler(SIGALRM, alarm_handler);
alarm(PPID_ALARM_INTERVAL);
// be sure to exit on SIGHUP, SIGPIPE
install_signal_handler(SIGHUP, signal_handler);
install_signal_handler(SIGPIPE, signal_handler);
}
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