libbb/safe_poll.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 2007 by Denys Vlasenko <vda.linux@googlemail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this tarball for details.
 */

#include "libbb.h"

/* Wrapper which restarts poll on EINTR or ENOMEM.
 * On other errors does perror("poll") and returns.
 * Warning! May take longer than timeout_ms to return! */
int safe_poll(struct pollfd *ufds, nfds_t nfds, int timeout)
{
	while (1) {
		int n = poll(ufds, nfds, timeout);
		if (n >= 0)
			return n;
		/* Make sure we inch towards completion */
		if (timeout > 0)
			timeout--;
		/* E.g. strace causes poll to return this */
		if (errno == EINTR)
			continue;
		/* Kernel is very low on memory. Retry. */
		/* I doubt many callers would handle this correctly! */
		if (errno == ENOMEM)
			continue;
		bb_perror_msg("poll");
		return n;
	}
}