// SPDX-License-Identifier: GPL-2.0-only /* 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> */ /* 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 <time.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. * * If you need to sleep, please use timeout_sleep() provided by this API. */ 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; } /* Sleep in a timeout section. * * nanosleep(2) can be used with this API since POSIX.1 explicitly * specifies that it does not interact with signals. */ int timeout_usleep(useconds_t usec) { struct timespec ts = { .tv_sec = usec / 1000000, .tv_nsec = (usec % 1000000) * 1000, }; return nanosleep(&ts, NULL); }