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// SPDX-License-Identifier: GPL-2.0-only
/* Timeout API for single-threaded programs that use blocking
* syscalls (read/write/send/recv/connect/accept).
*
* Copyright (C) 2017 Red Hat, Inc.
*
* Author: Stefan Hajnoczi <stefanha@redhat.com>
*/
/* Use the following pattern:
*
* timeout_begin(TIMEOUT);
* do {
* ret = accept(...);
* timeout_check("accept");
* } while (ret < 0 && ret == EINTR);
* timeout_end();
*/
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include "timeout.h"
static volatile bool timeout;
/* SIGALRM handler function. Do not use sleep(2), alarm(2), or
* setitimer(2) while using this API - they may interfere with each
* other.
*
* If you need to sleep, please use timeout_sleep() provided by this API.
*/
void sigalrm(int signo)
{
timeout = true;
}
/* Start a timeout. Call timeout_check() to verify that the timeout hasn't
* expired. timeout_end() must be called to stop the timeout. Timeouts cannot
* be nested.
*/
void timeout_begin(unsigned int seconds)
{
alarm(seconds);
}
/* Exit with an error message if the timeout has expired */
void timeout_check(const char *operation)
{
if (timeout) {
fprintf(stderr, "%s timed out\n", operation);
exit(EXIT_FAILURE);
}
}
/* Stop a timeout */
void timeout_end(void)
{
alarm(0);
timeout = false;
}
/* Sleep in a timeout section.
*
* nanosleep(2) can be used with this API since POSIX.1 explicitly
* specifies that it does not interact with signals.
*/
int timeout_usleep(useconds_t usec)
{
struct timespec ts = {
.tv_sec = usec / 1000000,
.tv_nsec = (usec % 1000000) * 1000,
};
return nanosleep(&ts, NULL);
}
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