Re: [Libguestfs] [PATCH] Rust bindings: Implement Event features

This patch includes: - Event callback handlers - Tests related to events(410-430) --- generator/rust.ml | 38 ++++++- rust/src/base.rs | 24 +++-- rust/src/error.rs | 8 +- rust/src/event.rs | 158 ++++++++++++++++++++++++++++ rust/src/lib.rs | 2 + rust/tests/040_create_multiple.rs | 2 +- rust/tests/410_close_event.rs | 38 +++++++ rust/tests/420_log_messages.rs | 60 +++++++++++ rust/tests/430_progress_messages.rs | 61 +++++++++++ 9 files changed, 381 insertions(+), 10 deletions(-) create mode 100644 rust/src/event.rs create mode 100644 rust/tests/410_close_event.rs create mode 100644 rust/tests/420_log_messages.rs create mode 100644 rust/tests/430_progress_messages.rs

diff --git a/rust/src/event.rs b/rust/src/event.rs new file mode 100644 index 000000000..942feec69 --- /dev/null +++ b/rust/src/event.rs @@ -0,0 +1,158 @@ +/* libguestfs Rust bindings + * Copyright (C) 2019 Hiroyuki Katsura <hiroyuki.katsura.0513(a)gmail.com&gt; + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library 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 + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +use crate::base; +use crate::error; +use crate::guestfs; +use std::ffi; +use std::os::raw::{c_char, c_void}; +use std::slice; +use std::sync; + +type GuestfsEventCallback = extern "C" fn( + *const base::guestfs_h, + *const c_void, + u64, + i32, + i32, + *const i8, + usize, + *const u64, + usize, +); + +#[link(name = "guestfs")] +extern "C" { + fn guestfs_set_event_callback( + g: *const base::guestfs_h, + cb: GuestfsEventCallback, + event_bitmask: u64, + flags: i32, + opaque: *const c_void, + ) -> i32; + fn guestfs_delete_event_callback(g: *const base::guestfs_h, eh: i32); + fn guestfs_event_to_string(bitmask: u64) -> *const c_char; + fn free(buf: *const c_void); +} + +#[derive(Hash, PartialEq, Eq)] +pub struct EventHandle { + eh: i32, +} + +pub type Callback = FnMut(guestfs::Event, EventHandle, &[i8], &[u64]); + +fn events_to_bitmask(v: &[guestfs::Event]) -> u64 { + let mut r = 0u64; + for x in v.iter() { + r |= x.to_u64(); + } + r +} + +pub fn event_to_string(events: &[guestfs::Event]) -> Result<String, error::Error> { + let bitmask = events_to_bitmask(events); + + let r = unsafe { guestfs_event_to_string(bitmask) }; + if r.is_null() { + Err(error::unix_error("event_to_string")) + } else { + let s = unsafe { ffi::CStr::from_ptr(r) }; + let s = s.to_str()?.to_string(); + unsafe { free(r as *const c_void) }; + Ok(s) + } +} + +/* -- Why Not Box<Callback> but Arc<Callback> (in struct base::Handle)? -- + * Assume that there are more than threads. While callback is running, + * if a thread frees the handle, automatically the buffer is freed if Box<Callback> + * is used. Therefore Arc<Callback> is used. + */ + +impl<'a> base::Handle<'a> { + pub fn set_event_callback<C: 'a>( + &mut self, + callback: C, + events: &[guestfs::Event], + ) -> Result<EventHandle, error::Error> + where + C: Fn(guestfs::Event, EventHandle, &[u8], &[u64]), + { + extern "C" fn trampoline<C>( + _g: *const base::guestfs_h, + opaque: *const c_void, + event: u64, + event_handle: i32, + _flags: i32, + buf: *const c_char, + buf_len: usize, + array: *const u64, + array_len: usize, + ) where + C: Fn(guestfs::Event, EventHandle, &[u8], &[u64]), + { + // trampoline function + // c.f. https://s3.amazonaws.com/temp.michaelfbryan.com/callbacks/index.html + + let event = match guestfs::Event::from_bitmask(event) { + Some(x) => x, + None => panic!("Failed to parse bitmask: {}", event), + }; + let eh = EventHandle { eh: event_handle }; + let buf = unsafe { slice::from_raw_parts(buf as *const u8, buf_len) }; + let array = unsafe { slice::from_raw_parts(array, array_len) }; + + let callback_ptr = unsafe { &*(opaque as *const sync::Arc<C>) }; + let callback = sync::Arc::clone(&callback_ptr); + callback(event, eh, buf, array) + } + let callback = sync::Arc::<C>::new(callback); + let event_bitmask = events_to_bitmask(events); + + let eh = { + // Weak::into_raw is nightly. + // In order to make sure that callback is freed when handle is freed, + // lifetime is explicitly declared. + let ptr: &'a sync::Arc<C> = Box::leak(Box::new(callback.clone()));