timerfd API on android (aarch64-linux-android && arm-linux-androideabi)

[DoumanAsh]

timerfd APIs are only available as SYS_* calls
As Android is linux, these should be available too.

Should they be added?

List of APIs:

• timerfd_create
• timerfd_settime
• timerfd_gettime

That's and various definitions like TFD_NONBLOCK

Reference http://man7.org/linux/man-pages/man2/timerfd_create.2.html

seems like they were added in api level 19, im sure that's depreciated by now

/*
 * Copyright (C) 2013 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#pragma once

/**
 * @file sys/timerfd.h
 * @brief Timer file descriptors.
 */

#include <fcntl.h> /* For O_CLOEXEC and O_NONBLOCK. */
#include <time.h>
#include <sys/cdefs.h>
#include <sys/types.h>

__BEGIN_DECLS

/** The timerfd_create() flag for a close-on-exec file descriptor. */
#define TFD_CLOEXEC O_CLOEXEC
/** The timerfd_create() flag for a non-blocking file descriptor. */
#define TFD_NONBLOCK O_NONBLOCK

/**
 * [timerfd_create(2)](http://man7.org/linux/man-pages/man2/timerfd_create.2.html) creates a
 * timer file descriptor.
 *
 * Returns the new file descriptor on success, and returns -1 and sets `errno` on failure.
 *
 * Available since API level 19.
 */

#if __ANDROID_API__ >= 19
int timerfd_create(clockid_t __clock, int __flags) __INTRODUCED_IN(19);
#endif /* __ANDROID_API__ >= 19 */


/** The timerfd_settime() flag to use absolute rather than relative times. */
#define TFD_TIMER_ABSTIME (1 << 0)
/** The timerfd_settime() flag to cancel an absolute timer if the realtime clock changes. */
#define TFD_TIMER_CANCEL_ON_SET (1 << 1)

/**
 * [timerfd_settime(2)](http://man7.org/linux/man-pages/man2/timerfd_settime.2.html) starts or
 * stops a timer.
 *
 * Returns 0 on success, and returns -1 and sets `errno` on failure.
 *
 * Available since API level 19.
 */

#if __ANDROID_API__ >= 19
int timerfd_settime(int __fd, int __flags, const struct itimerspec* __new_value, struct itimerspec* __old_value) __INTRODUCED_IN(19);

/**
 * [timerfd_gettime(2)](http://man7.org/linux/man-pages/man2/timerfd_gettime.2.html) queries the
 * current timer settings.
 *
 * Returns 0 on success, and returns -1 and sets `errno` on failure.
 *
 * Available since API level 19.
 */
int timerfd_gettime(int __fd, struct itimerspec* __current_value) __INTRODUCED_IN(19);
#endif /* __ANDROID_API__ >= 19 */


__END_DECLS

[saurik]

seems like they were added in api level 19, im sure that's depreciated by now

Multiple people--including the person who submitted the pull request #1751--seem to have read this wording and got confused; I'm assuming you mean that API level 19 (Android 4.4) is sufficiently old such that many people can feel comfortable using APIs from it, not that anything has been "deprecated". That PR should be resurrected and committed (as I'd argue that old versions of non-Android Linux are of course also missing these APIs, and yet it is available there).

[DoumanAsh]

@saurik While it is unfortunate that libc decided on such weird way to deal with API version.
It is not difficult to write imports yourself. See my timer crate:

https://github.com/DoumanAsh/async-timer/blob/master/src/timer/timer_fd.rs#L9-L23