tools/testing/vsock/timeout.c

   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 }