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0b025033 SH |
1 | /* Timeout API for single-threaded programs that use blocking |
2 | * syscalls (read/write/send/recv/connect/accept). | |
3 | * | |
4 | * Copyright (C) 2017 Red Hat, Inc. | |
5 | * | |
6 | * Author: Stefan Hajnoczi <stefanha@redhat.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; version 2 | |
11 | * of the License. | |
12 | */ | |
13 | ||
14 | /* Use the following pattern: | |
15 | * | |
16 | * timeout_begin(TIMEOUT); | |
17 | * do { | |
18 | * ret = accept(...); | |
19 | * timeout_check("accept"); | |
20 | * } while (ret < 0 && ret == EINTR); | |
21 | * timeout_end(); | |
22 | */ | |
23 | ||
24 | #include <stdlib.h> | |
25 | #include <stdbool.h> | |
26 | #include <unistd.h> | |
27 | #include <stdio.h> | |
28 | #include "timeout.h" | |
29 | ||
30 | static volatile bool timeout; | |
31 | ||
32 | /* SIGALRM handler function. Do not use sleep(2), alarm(2), or | |
33 | * setitimer(2) while using this API - they may interfere with each | |
34 | * other. | |
35 | */ | |
36 | void sigalrm(int signo) | |
37 | { | |
38 | timeout = true; | |
39 | } | |
40 | ||
41 | /* Start a timeout. Call timeout_check() to verify that the timeout hasn't | |
42 | * expired. timeout_end() must be called to stop the timeout. Timeouts cannot | |
43 | * be nested. | |
44 | */ | |
45 | void timeout_begin(unsigned int seconds) | |
46 | { | |
47 | alarm(seconds); | |
48 | } | |
49 | ||
50 | /* Exit with an error message if the timeout has expired */ | |
51 | void timeout_check(const char *operation) | |
52 | { | |
53 | if (timeout) { | |
54 | fprintf(stderr, "%s timed out\n", operation); | |
55 | exit(EXIT_FAILURE); | |
56 | } | |
57 | } | |
58 | ||
59 | /* Stop a timeout */ | |
60 | void timeout_end(void) | |
61 | { | |
62 | alarm(0); | |
63 | timeout = false; | |
64 | } |