Rust bindings: Implement callback handlers

This patch includes:

- Event callback handlers
- Tests related to events(410-430)

src/bin/event.rs and src/bin/event_leak.rs
are the PoCs that Boxes related to callbacks are
not leaked.

rust/src/bin/event.rs

@@ -0,0 +1,29 @@
+extern crate guestfs;
+use guestfs::*;
+
+fn main() {
+    for _ in 0..256 {
+        let mut g = match Handle::create() {
+            Ok(g) => g,
+            Err(e) => panic!(format!(" could not create handle {:?}", e)),
+        };
+        g.set_event_callback(
+            |e, _, _, _| match e {
+                Event::Close => print!("c"),
+                _ => print!("o"),
+            },
+            &EVENT_ALL,
+        )
+        .unwrap();
+        let eh = g
+            .set_event_callback(|_, _, _, _| print!("n"), &EVENT_ALL)
+            .unwrap();
+        g.set_trace(true).unwrap();
+        g.delete_event_callback(eh).unwrap();
+        g.set_trace(false).unwrap();
+    }
+    let _v = vec![0; 1024 * 1024];
+    // no leak
+    // mem::forget(v);
+    println!()
+}

rust/src/bin/event_leak.rs

@@ -0,0 +1,30 @@
+extern crate guestfs;
+use guestfs::*;
+use std::mem;
+
+fn main() {
+    for _ in 0..256 {
+        let mut g = match Handle::create() {
+            Ok(g) => g,
+            Err(e) => panic!(format!(" could not create handle {:?}", e)),
+        };
+        g.set_event_callback(
+            |e, _, _, _| match e {
+                Event::Close => print!("c"),
+                _ => print!("o"),
+            },
+            &EVENT_ALL,
+        )
+        .unwrap();
+        let eh = g
+            .set_event_callback(|_, _, _, _| print!("n"), &EVENT_ALL)
+            .unwrap();
+        g.set_trace(true).unwrap();
+        g.delete_event_callback(eh).unwrap();
+        g.set_trace(false).unwrap();
+    }
+    let v = vec![0; 1024 * 1024];
+    // leak
+    mem::forget(v);
+    println!()
+}

rust/src/error.rs

@@ -20,6 +20,7 @@ use crate::base;
 use crate::utils;
 use std::convert;
 use std::ffi;
+use std::io;
 use std::os::raw::{c_char, c_int};
 use std::str;
 
@@ -41,6 +42,7 @@ pub enum Error {
     API(APIError),
     IllegalString(ffi::NulError),
     Utf8Error(str::Utf8Error),
+    UnixError(io::Error, &'static str),
     Create,
 }
 
@@ -56,6 +58,10 @@ impl convert::From<str::Utf8Error> for Error {
     }
 }
 
+pub(crate) fn unix_error(operation: &'static str) -> Error {
+    Error::UnixError(io::Error::last_os_error(), operation)
+}
+
 impl<'a> base::Handle<'a> {
     pub(crate) fn get_error_from_handle(&self, operation: &'static str) -> Error {
         let c_msg = unsafe { guestfs_last_error(self.g) };

rust/src/event.rs

@@ -1,4 +1,150 @@
+/* libguestfs Rust bindings
+ * Copyright (C) 2019 Hiroyuki Katsura <hiroyuki.katsura.0513@gmail.com>
+ *
+ * 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 crate::utils;
+use std::os::raw::{c_char, c_void};
+use std::slice;
+
+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,
 }
+
+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 { utils::char_ptr_to_string(r) };
+        unsafe { free(r as *const c_void) };
+        Ok(s?)
+    }
+}
+
+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]) + 'a,
+    {
+        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: &Box<dyn Fn(guestfs::Event, EventHandle, &[u8], &[u64])> =
+                Box::leak(unsafe { Box::from_raw(opaque as *mut _) });
+            callback(event, eh, buf, array)
+        }
+
+        // Because trait pointer is fat pointer, in order to pass it to API,
+        // double Box is used.
+        let callback: Box<Box<dyn Fn(guestfs::Event, EventHandle, &[u8], &[u64]) + 'a>> =
+            Box::new(Box::new(callback));
+        let ptr = Box::into_raw(callback);
+        let callback = unsafe { Box::from_raw(ptr) };
+        let event_bitmask = events_to_bitmask(events);
+
+        let eh = {
+            unsafe {
+                guestfs_set_event_callback(
+                    self.g,
+                    trampoline::<C>,
+                    event_bitmask,
+                    0,
+                    ptr as *const c_void,
+                )
+            }
+        };
+        if eh == -1 {
+            return Err(self.get_error_from_handle("set_event_callback"));
+        }
+        self.callbacks.insert(EventHandle { eh }, callback);
+
+        Ok(EventHandle { eh })
+    }
+
+    pub fn delete_event_callback(&mut self, eh: EventHandle) -> Result<(), error::Error> {
+        unsafe {
+            guestfs_delete_event_callback(self.g, eh.eh);
+        }
+        self.callbacks.remove(&eh);
+        Ok(())
+    }
+}

rust/tests/410_close_event.rs

@@ -0,0 +1,39 @@
+/* libguestfs Rust bindings
+ * Copyright (C) 2019 Hiroyuki Katsura <hiroyuki.katsura.0513@gmail.com>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+extern crate guestfs;
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+#[test]
+fn close_event() {
+    let close_invoked = Rc::new(RefCell::new(0));
+    {
+        let mut g = guestfs::Handle::create().expect("create");
+        g.set_event_callback(
+            |_, _, _, _| {
+                *close_invoked.borrow_mut() += 1;
+            },
+            &[guestfs::Event::Close],
+        )
+        .unwrap();
+        assert_eq!(*close_invoked.borrow(), 0);
+    }
+    assert_eq!(*close_invoked.borrow(), 1);
+}

rust/tests/420_log_messages.rs

@@ -0,0 +1,60 @@
+/* libguestfs Rust bindings
+ * Copyright (C) 2019 Hiroyuki Katsura <hiroyuki.katsura.0513@gmail.com>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+extern crate guestfs;
+
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::str;
+
+#[test]
+fn log_messages() {
+    let callback_invoked = Rc::new(RefCell::new(0));
+    {
+        let mut g = guestfs::Handle::create().expect("create");
+        g.set_event_callback(
+            |ev, _, buf, array| {
+                *callback_invoked.borrow_mut() += 1;
+
+                let event = guestfs::event_to_string(&[ev]).unwrap();
+
+                let buf = str::from_utf8(buf).unwrap();
+                let array = array
+                    .into_iter()
+                    .map(|x| format!("{}", x))
+                    .collect::<Vec<String>>()
+                    .join(",");
+
+                eprintln!("event logged: event={} buf={} array={}", event, buf, array)
+            },
+            &[
+                guestfs::Event::Appliance,
+                guestfs::Event::Library,
+                guestfs::Event::Warning,
+                guestfs::Event::Trace,
+            ],
+        )
+        .unwrap();
+
+        g.set_trace(true).unwrap();
+        g.set_verbose(true).unwrap();
+        g.add_drive_ro("/dev/null").unwrap();
+        g.set_autosync(true).unwrap();
+    }
+    assert!(*callback_invoked.borrow() > 0);
+}

rust/tests/430_progress_messages.rs

@@ -0,0 +1,59 @@
+/* libguestfs Rust bindings
+ * Copyright (C) 2019 Hiroyuki Katsura <hiroyuki.katsura.0513@gmail.com>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+extern crate guestfs;
+
+use std::cell::RefCell;
+use std::default::Default;
+use std::rc::Rc;
+
+#[test]
+fn progress_messages() {
+    let callback_invoked = Rc::new(RefCell::new(0));
+    {
+        let mut g = guestfs::Handle::create().expect("create");
+        g.add_drive("/dev/null", Default::default()).unwrap();
+        g.launch().unwrap();
+
+        let eh = g
+            .set_event_callback(
+                |_, _, _, _| {
+                    *callback_invoked.borrow_mut() += 1;
+                },
+                &[guestfs::Event::Progress],
+            )
+            .unwrap();
+        assert_eq!("ok", g.debug("progress", &["5"]).unwrap());
+        assert!(*callback_invoked.borrow() > 0);
+
+        *callback_invoked.borrow_mut() = 0;
+        g.delete_event_callback(eh).unwrap();
+        assert_eq!("ok", g.debug("progress", &["5"]).unwrap());
+        assert_eq!(*callback_invoked.borrow(), 0);
+
+        g.set_event_callback(
+            |_, _, _, _| {
+                *callback_invoked.borrow_mut() += 1;
+            },
+            &[guestfs::Event::Progress],
+        )
+        .unwrap();
+        assert_eq!("ok", g.debug("progress", &["5"]).unwrap());
+    }
+    assert!(*callback_invoked.borrow() > 0);
+}