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// Copyright 2017 Lyndon Brown // // This file is part of the PulseAudio Rust language binding. // // Licensed under the MIT license or the Apache license (version 2.0), at your option. You may not // copy, modify, or distribute this file except in compliance with said license. You can find copies // of these licenses either in the LICENSE-MIT and LICENSE-APACHE files, or alternatively at // <http://opensource.org/licenses/MIT> and <http://www.apache.org/licenses/LICENSE-2.0> // respectively. // // Portions of documentation are copied from the LGPL 2.1+ licensed PulseAudio C headers on a // fair-use basis, as discussed in the overall project readme (available in the git repository). //! UNIX signal support for main loops. //! //! # Overview //! //! In contrast to other main loop event sources such as timer and IO events, UNIX signal support //! requires modification of the global process environment. Due to this the generic main loop //! abstraction layer as defined in [`mainloop::api`](../api/index.html) doesn’t have direct support //! for UNIX signals. However, you may hook signal support into an abstract main loop via the //! routines defined herein. use std::os::raw::c_void; use std::ptr::null_mut; use capi::pa_signal_event as EventInternal; use crate::error::PAErr; use crate::callbacks::MultiUseCallback; use crate::mainloop::api::{ApiInternal, MainloopInnerType, Mainloop as MainloopTrait}; /// An opaque UNIX signal event source object. /// /// Note: Saves a copy of the closure callbacks, which it frees on drop. pub struct Event { /// The actual C object. ptr: *mut EventInternal, /// Saved multi-use state callback closure, for later destruction. _signal_cb: SignalCb, } type SignalCb = MultiUseCallback<dyn FnMut(i32), extern "C" fn(*const ApiInternal, *mut EventInternal, i32, *mut c_void)>; /// Trait with signal handling, for mainloops. pub trait MainloopSignals : MainloopTrait { /// Initializes the UNIX signal subsystem and bind it to the specified main loop. fn init_signals(&mut self) -> Result<(), PAErr> { let inner = self.inner(); let api = inner.get_api(); match unsafe { capi::pa_signal_init(api.into()) } { 0 => Ok(()), e => Err(PAErr(e)), } } /// Cleans up the signal subsystem. #[inline] fn signals_done(&self) { unsafe { capi::pa_signal_done(); } } } impl Event { /// Creates a new UNIX signal event source object. /// /// The callback must accept an integer which represents the signal. pub fn new<F>(sig: i32, callback: F) -> Self where F: FnMut(i32) + 'static { let saved = SignalCb::new(Some(Box::new(callback))); let (cb_fn, cb_data) = saved.get_capi_params(signal_cb_proxy); let ptr = unsafe { capi::pa_signal_new(sig, cb_fn, cb_data) }; Self { ptr: ptr, _signal_cb: saved } } } impl Drop for Event { fn drop(&mut self) { unsafe { capi::pa_signal_free(self.ptr) }; self.ptr = null_mut::<EventInternal>(); } } /// Proxy for signal callbacks. /// /// Warning: This is for multi-use cases! It does **not** destroy the actual closure callback, which /// must be accomplished separately to avoid a memory leak. extern "C" fn signal_cb_proxy(_api: *const ApiInternal, _e: *mut EventInternal, sig: i32, userdata: *mut c_void) { let _ = std::panic::catch_unwind(|| { let callback = SignalCb::get_callback(userdata); (callback)(sig); }); }