summaryrefslogtreecommitdiffstats
path: root/event_notifier.c
blob: 5b7c1cdc0d3875a64e9f5accf0a91b79ce9334a5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
/*
 * Based on:
 *  1) file-posix.c of QEMU Project
 *
 *     Copyright (c) 2006 Fabrice Bellard
 *
 *  2) event_notifier-posix.c of QEMU Project
 *
 *     Copyright Red Hat, Inc. 2010
 *
 *     Authors:
 *      Michael S. Tsirkin <mst@redhat.com>
 *
 *  3) os-posix-lib.c of QEMU project
 *
 *     Copyright (c) 2003-2008 Fabrice Bellard
 *     Copyright (c) 2010 Red Hat, Inc.
 *
 * Copyright 2023 Virtual Open Systems SAS.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */


#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <sys/eventfd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <pthread.h>
#include <stdbool.h>
#include <sys/param.h>
#include <assert.h>

/* For socket */
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

/* Project header files */
#include "vhost_user_loopback.h"


/* Sets a specific flag */
int fcntl_setfl(int fd, int flag)
{
    int flags;

    flags = fcntl(fd, F_GETFL);
    if (flags == -1) {
        return -errno;
    }

    if (fcntl(fd, F_SETFL, flags | flag) == -1) {
        return -errno;
    }

    return 0;
}

void qemu_set_cloexec(int fd)
{
    int f;
    f = fcntl(fd, F_GETFD);
    f = fcntl(fd, F_SETFD, f | FD_CLOEXEC);
}

/*
 * Creates a pipe with FD_CLOEXEC set on both file descriptors
 */
int qemu_pipe(int pipefd[2])
{
    int ret;

#ifdef CONFIG_PIPE2
    ret = pipe2(pipefd, O_CLOEXEC);
    if (ret != -1 || errno != ENOSYS) {
        return ret;
    }
#endif
    ret = pipe(pipefd);
    if (ret == 0) {
        qemu_set_cloexec(pipefd[0]);
        qemu_set_cloexec(pipefd[1]);
    }

    return ret;
}

int event_notifier_get_fd(const EventNotifier *e)
{
    return e->rfd;
}

int event_notifier_get_wfd(const EventNotifier *e)
{
    return e->wfd;
}

int event_notifier_set(EventNotifier *e)
{
    static const uint64_t value = 1;
    ssize_t ret;

    if (!e->initialized) {
        return -1;
    }

    do {
        ret = write(e->wfd, &value, sizeof(value));
    } while (ret < 0 && errno == EINTR);

    /* EAGAIN is fine, a read must be pending.  */
    if (ret < 0 && errno != EAGAIN) {
        return -errno;
    }
    return 0;
}

int event_notifier_init(EventNotifier *e, int active)
{
    int fds[2];
    int ret;

    ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);

    if (ret >= 0) {
        e->rfd = e->wfd = ret;
    } else {
        if (errno != ENOSYS) {
            return -errno;
        }
        if (qemu_pipe(fds) < 0) {
            return -errno;
        }
        ret = fcntl_setfl(fds[0], O_NONBLOCK);
        if (ret < 0) {
            ret = -errno;
            goto fail;
        }
        ret = fcntl_setfl(fds[1], O_NONBLOCK);
        if (ret < 0) {
            ret = -errno;
            goto fail;
        }
        e->rfd = fds[0];
        e->wfd = fds[1];
    }
    e->initialized = true;
    if (active) {
        event_notifier_set(e);
    }
    return 0;

fail:
    close(fds[0]);
    close(fds[1]);
    return ret;
}

bool ioeventfd_enabled(void)
{
    /*
     * TODO: Delete if not needed:
     * return !kvm_enabled() || kvm_eventfds_enabled();
     */
    return 1;
}

int event_notifier_test_and_clear(EventNotifier *e)
{
    int value;
    ssize_t len;
    char buffer[512];

    if (!e->initialized) {
        return 0;
    }

    /* Drain the notify pipe.  For eventfd, only 8 bytes will be read.  */
    value = 0;
    do {
        len = read(e->rfd, buffer, sizeof(buffer));
        value |= (len > 0);
    } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));

    return value;
}