1// SPDX-License-Identifier: GPL-2.0
2//
3// waiter-epoll.c - Waiter for event notification by epoll(7).
4//
5// Copyright (c) 2018 Takashi Sakamoto <o-takashi@sakamocchi.jp>
6//
7// Licensed under the terms of the GNU General Public License, version 2.
8
9#include "waiter.h"
10#include "misc.h"
11
12#include <stdlib.h>
13#include <unistd.h>
14#include <string.h>
15#include <errno.h>
16#include <sys/types.h>
17#include <sys/epoll.h>
18
19struct epoll_state {
20	int epfd;
21	struct epoll_event *events;
22	unsigned int ev_count;
23};
24
25static int epoll_prepare(struct waiter_context *waiter)
26{
27	struct epoll_state *state = waiter->private_data;
28	int i;
29
30	state->ev_count = waiter->pfd_count;
31	state->events = calloc(state->ev_count, sizeof(*state->events));
32	if (state->events == NULL)
33		return -ENOMEM;
34
35	state->epfd = epoll_create(1);
36	if (state->epfd < 0)
37		return -errno;
38
39	for (i = 0; i < (int)waiter->pfd_count; ++i) {
40		struct epoll_event ev = {
41			.data.fd = waiter->pfds[i].fd,
42			.events = waiter->pfds[i].events,
43		};
44		if (epoll_ctl(state->epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
45			return -errno;
46	}
47
48	return 0;
49}
50
51static int epoll_wait_event(struct waiter_context *waiter, int timeout_msec)
52{
53	struct epoll_state *state = waiter->private_data;
54	unsigned int ev_count;
55	int i, j;
56	int err;
57
58	memset(state->events, 0, state->ev_count * sizeof(*state->events));
59	err = epoll_wait(state->epfd, state->events, state->ev_count,
60			 timeout_msec);
61	if (err < 0)
62		return -errno;
63	ev_count = (unsigned int)err;
64
65	if (ev_count > 0) {
66		// Reconstruct data of pollfd structure.
67		for (i = 0; i < (int)ev_count; ++i) {
68			struct epoll_event *ev = &state->events[i];
69			for (j = 0; j < (int)waiter->pfd_count; ++j) {
70				if (waiter->pfds[i].fd == ev->data.fd) {
71					waiter->pfds[i].revents = ev->events;
72					break;
73				}
74			}
75		}
76	}
77
78	return ev_count;
79}
80
81static void epoll_release(struct waiter_context *waiter)
82{
83	struct epoll_state *state = waiter->private_data;
84	int i;
85
86	for (i = 0; i < (int)waiter->pfd_count; ++i) {
87		int fd = waiter->pfds[i].fd;
88		epoll_ctl(state->epfd, EPOLL_CTL_DEL, fd, NULL);
89	}
90
91	free(state->events);
92	state->events = NULL;
93
94	close(state->epfd);
95
96	state->ev_count = 0;
97	state->epfd = 0;
98}
99
100const struct waiter_data waiter_epoll = {
101	.ops = {
102		.prepare	= epoll_prepare,
103		.wait_event	= epoll_wait_event,
104		.release	= epoll_release,
105	},
106	.private_size = sizeof(struct epoll_state),
107};
108