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