/* Timeout API for single-threaded programs that use blocking * syscalls (read/write/send/recv/connect/accept). * * Copyright (C) 2017 Red Hat, Inc. * * Author: Stefan Hajnoczi <stefanha@redhat.com> * * This program 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; version 2 * of the License. */ /* Use the following pattern: * *   timeout_begin(TIMEOUT); *   do { *       ret = accept(...); *       timeout_check("accept"); *   } while (ret < 0 && ret == EINTR); *   timeout_end(); */ #include <stdlib.h>#include <stdbool.h>#include <unistd.h>#include <stdio.h>#include "timeout.h" static volatile bool timeout; /* SIGALRM handler function.  Do not use sleep(2), alarm(2), or * setitimer(2) while using this API - they may interfere with each * other. */void sigalrm(int signo){	timeout = true;} /* Start a timeout.  Call timeout_check() to verify that the timeout hasn't * expired.  timeout_end() must be called to stop the timeout.  Timeouts cannot * be nested. */void timeout_begin(unsigned int seconds){	alarm(seconds);} /* Exit with an error message if the timeout has expired */void timeout_check(const char *operation){	if (timeout) {		fprintf(stderr, "%s timed out\n", operation);		exit(EXIT_FAILURE);	}} /* Stop a timeout */void timeout_end(void){	alarm(0);	timeout = false;}