tools/testing/vsock/timeout.c

   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 }