1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Timeout API for single-threaded programs that use blocking |
3 | * syscalls (read/write/send/recv/connect/accept). |
4 | * |
5 | * Copyright (C) 2017 Red Hat, Inc. |
6 | * |
7 | * Author: Stefan Hajnoczi <stefanha@redhat.com> |
8 | */ |
9 | |
10 | /* Use the following pattern: |
11 | * |
12 | * timeout_begin(TIMEOUT); |
13 | * do { |
14 | * ret = accept(...); |
15 | * timeout_check("accept"); |
16 | * } while (ret < 0 && ret == EINTR); |
17 | * timeout_end(); |
18 | */ |
19 | |
20 | #include <stdlib.h> |
21 | #include <stdbool.h> |
22 | #include <unistd.h> |
23 | #include <stdio.h> |
24 | #include "timeout.h" |
25 | |
26 | static volatile bool timeout; |
27 | |
28 | /* SIGALRM handler function. Do not use sleep(2), alarm(2), or |
29 | * setitimer(2) while using this API - they may interfere with each |
30 | * other. |
31 | */ |
32 | void sigalrm(int signo) |
33 | { |
34 | timeout = true; |
35 | } |
36 | |
37 | /* Start a timeout. Call timeout_check() to verify that the timeout hasn't |
38 | * expired. timeout_end() must be called to stop the timeout. Timeouts cannot |
39 | * be nested. |
40 | */ |
41 | void timeout_begin(unsigned int seconds) |
42 | { |
43 | alarm(seconds); |
44 | } |
45 | |
46 | /* Exit with an error message if the timeout has expired */ |
47 | void timeout_check(const char *operation) |
48 | { |
49 | if (timeout) { |
50 | fprintf(stderr, "%s timed out\n" , operation); |
51 | exit(EXIT_FAILURE); |
52 | } |
53 | } |
54 | |
55 | /* Stop a timeout */ |
56 | void timeout_end(void) |
57 | { |
58 | alarm(0); |
59 | timeout = false; |
60 | } |
61 | |