LXR linux/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
  26static 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 */
  32void 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 */
  41void timeout_begin(unsigned int seconds)
  42{
  43        alarm(seconds);
  44}
  45
  46/* Exit with an error message if the timeout has expired */
  47void 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 */
  56void timeout_end(void)
  57{
  58        alarm(0);
  59        timeout = false;
  60}
  61