diff options
Diffstat (limited to 'rust/chardev')
| -rw-r--r-- | rust/chardev/Cargo.toml | 24 | ||||
| l--------- | rust/chardev/build.rs | 1 | ||||
| -rw-r--r-- | rust/chardev/meson.build | 42 | ||||
| -rw-r--r-- | rust/chardev/src/bindings.rs | 40 | ||||
| -rw-r--r-- | rust/chardev/src/chardev.rs | 261 | ||||
| -rw-r--r-- | rust/chardev/src/lib.rs | 6 | ||||
| -rw-r--r-- | rust/chardev/wrapper.h | 28 |
7 files changed, 402 insertions, 0 deletions
diff --git a/rust/chardev/Cargo.toml b/rust/chardev/Cargo.toml new file mode 100644 index 0000000..f105189 --- /dev/null +++ b/rust/chardev/Cargo.toml @@ -0,0 +1,24 @@ +[package] +name = "chardev" +version = "0.1.0" +description = "Rust bindings for QEMU/chardev" +resolver = "2" +publish = false + +authors.workspace = true +edition.workspace = true +homepage.workspace = true +license.workspace = true +repository.workspace = true +rust-version.workspace = true + +[dependencies] +glib-sys = { workspace = true } +common = { path = "../common" } +bql = { path = "../bql" } +migration = { path = "../migration" } +qom = { path = "../qom" } +util = { path = "../util" } + +[lints] +workspace = true diff --git a/rust/chardev/build.rs b/rust/chardev/build.rs new file mode 120000 index 0000000..71a3167 --- /dev/null +++ b/rust/chardev/build.rs @@ -0,0 +1 @@ +../util/build.rs
\ No newline at end of file diff --git a/rust/chardev/meson.build b/rust/chardev/meson.build new file mode 100644 index 0000000..d365d8d --- /dev/null +++ b/rust/chardev/meson.build @@ -0,0 +1,42 @@ +c_enums = [ + 'QEMUChrEvent', +] +_chardev_bindgen_args = [] +foreach enum : c_enums + _chardev_bindgen_args += ['--rustified-enum', enum] +endforeach + +# TODO: Remove this comment when the clang/libclang mismatch issue is solved. +# +# Rust bindings generation with `bindgen` might fail in some cases where the +# detected `libclang` does not match the expected `clang` version/target. In +# this case you must pass the path to `clang` and `libclang` to your build +# command invocation using the environment variables CLANG_PATH and +# LIBCLANG_PATH +_chardev_bindings_inc_rs = rust.bindgen( + input: 'wrapper.h', + dependencies: common_ss.all_dependencies(), + output: 'bindings.inc.rs', + include_directories: bindings_incdir, + bindgen_version: ['>=0.60.0'], + args: bindgen_args_common + _chardev_bindgen_args, + c_args: bindgen_c_args, +) + +_chardev_rs = static_library( + 'chardev', + structured_sources( + [ + 'src/lib.rs', + 'src/bindings.rs', + 'src/chardev.rs', + ], + {'.': _chardev_bindings_inc_rs} + ), + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + link_with: [_bql_rs, _migration_rs, _qom_rs, _util_rs], + dependencies: [glib_sys_rs, common_rs, qemu_macros], +) + +chardev_rs = declare_dependency(link_with: [_chardev_rs], dependencies: [chardev, qemuutil]) diff --git a/rust/chardev/src/bindings.rs b/rust/chardev/src/bindings.rs new file mode 100644 index 0000000..c95dc89 --- /dev/null +++ b/rust/chardev/src/bindings.rs @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#![allow( + dead_code, + improper_ctypes_definitions, + improper_ctypes, + non_camel_case_types, + non_snake_case, + non_upper_case_globals, + unnecessary_transmutes, + unsafe_op_in_unsafe_fn, + clippy::pedantic, + clippy::restriction, + clippy::style, + clippy::missing_const_for_fn, + clippy::ptr_offset_with_cast, + clippy::useless_transmute, + clippy::missing_safety_doc, + clippy::too_many_arguments +)] + +use common::Zeroable; +use glib_sys::{ + gboolean, guint, GArray, GHashTable, GHashTableIter, GIOCondition, GList, GMainContext, + GPollFD, GPtrArray, GQueue, GSList, GSource, GSourceFunc, +}; + +#[cfg(MESON)] +include!("bindings.inc.rs"); + +#[cfg(not(MESON))] +include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs")); + +// SAFETY: these are implemented in C; the bindings need to assert that the +// BQL is taken, either directly or via `BqlCell` and `BqlRefCell`. +// When bindings for character devices are introduced, this can be +// moved to the Opaque<> wrapper in src/chardev.rs. +unsafe impl Send for CharBackend {} +unsafe impl Sync for CharBackend {} + +unsafe impl Zeroable for CharBackend {} diff --git a/rust/chardev/src/chardev.rs b/rust/chardev/src/chardev.rs new file mode 100644 index 0000000..2014479 --- /dev/null +++ b/rust/chardev/src/chardev.rs @@ -0,0 +1,261 @@ +// Copyright 2024 Red Hat, Inc. +// Author(s): Paolo Bonzini <pbonzini@redhat.com> +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Bindings for character devices +//! +//! Character devices in QEMU can run under the big QEMU lock or in a separate +//! `GMainContext`. Here we only support the former, because the bindings +//! enforce that the BQL is taken whenever the functions in [`CharBackend`] are +//! called. + +use std::{ + ffi::{c_int, c_void, CStr}, + fmt::{self, Debug}, + io::{self, ErrorKind, Write}, + marker::PhantomPinned, + ptr::addr_of_mut, + slice, +}; + +use bql::{BqlRefCell, BqlRefMut}; +use common::{callbacks::FnCall, errno, Opaque}; +use qom::prelude::*; + +use crate::bindings; + +/// A safe wrapper around [`bindings::Chardev`]. +#[repr(transparent)] +#[derive(common::Wrapper)] +pub struct Chardev(Opaque<bindings::Chardev>); + +pub type ChardevClass = bindings::ChardevClass; +pub type Event = bindings::QEMUChrEvent; + +/// A safe wrapper around [`bindings::CharBackend`], denoting the character +/// back-end that is used for example by a device. Compared to the +/// underlying C struct it adds BQL protection, and is marked as pinned +/// because the QOM object ([`bindings::Chardev`]) contains a pointer to +/// the `CharBackend`. +pub struct CharBackend { + inner: BqlRefCell<bindings::CharBackend>, + _pin: PhantomPinned, +} + +pub struct CharBackendMut<'a>(BqlRefMut<'a, bindings::CharBackend>); + +impl Write for CharBackendMut<'_> { + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } + + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + let chr: &mut bindings::CharBackend = &mut self.0; + + let len = buf.len().try_into().unwrap(); + let r = unsafe { bindings::qemu_chr_fe_write(addr_of_mut!(*chr), buf.as_ptr(), len) }; + errno::into_io_result(r).map(|cnt| cnt as usize) + } + + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + let chr: &mut bindings::CharBackend = &mut self.0; + + let len = buf.len().try_into().unwrap(); + let r = unsafe { bindings::qemu_chr_fe_write_all(addr_of_mut!(*chr), buf.as_ptr(), len) }; + errno::into_io_result(r).and_then(|cnt| { + if cnt as usize == buf.len() { + Ok(()) + } else { + Err(ErrorKind::WriteZero.into()) + } + }) + } +} + +impl Debug for CharBackend { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + // SAFETY: accessed just to print the values + let chr = self.inner.as_ptr(); + Debug::fmt(unsafe { &*chr }, f) + } +} + +// FIXME: use something like PinnedDrop from the pinned_init crate +impl Drop for CharBackend { + fn drop(&mut self) { + self.disable_handlers(); + } +} + +impl CharBackend { + /// Enable the front-end's character device handlers, if there is an + /// associated `Chardev`. + pub fn enable_handlers< + 'chardev, + 'owner: 'chardev, + T, + CanReceiveFn: for<'a> FnCall<(&'a T,), u32>, + ReceiveFn: for<'a, 'b> FnCall<(&'a T, &'b [u8])>, + EventFn: for<'a> FnCall<(&'a T, Event)>, + >( + // When "self" is dropped, the handlers are automatically disabled. + // However, this is not necessarily true if the owner is dropped. + // So require the owner to outlive the character device. + &'chardev self, + owner: &'owner T, + _can_receive: CanReceiveFn, + _receive: ReceiveFn, + _event: EventFn, + ) { + unsafe extern "C" fn rust_can_receive_cb<T, F: for<'a> FnCall<(&'a T,), u32>>( + opaque: *mut c_void, + ) -> c_int { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::<T>()) }; + let r = F::call((owner,)); + r.try_into().unwrap() + } + + unsafe extern "C" fn rust_receive_cb<T, F: for<'a, 'b> FnCall<(&'a T, &'b [u8])>>( + opaque: *mut c_void, + buf: *const u8, + size: c_int, + ) { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::<T>()) }; + let buf = unsafe { slice::from_raw_parts(buf, size.try_into().unwrap()) }; + F::call((owner, buf)) + } + + unsafe extern "C" fn rust_event_cb<T, F: for<'a> FnCall<(&'a T, Event)>>( + opaque: *mut c_void, + event: Event, + ) { + // SAFETY: the values are safe according to the contract of + // enable_handlers() and qemu_chr_fe_set_handlers() + let owner: &T = unsafe { &*(opaque.cast::<T>()) }; + F::call((owner, event)) + } + + const { assert!(CanReceiveFn::IS_SOME) }; + let receive_cb: Option<unsafe extern "C" fn(*mut c_void, *const u8, c_int)> = + if ReceiveFn::is_some() { + Some(rust_receive_cb::<T, ReceiveFn>) + } else { + None + }; + let event_cb: Option<unsafe extern "C" fn(*mut c_void, Event)> = if EventFn::is_some() { + Some(rust_event_cb::<T, EventFn>) + } else { + None + }; + + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { + bindings::qemu_chr_fe_set_handlers( + addr_of_mut!(*chr), + Some(rust_can_receive_cb::<T, CanReceiveFn>), + receive_cb, + event_cb, + None, + (owner as *const T).cast_mut().cast::<c_void>(), + core::ptr::null_mut(), + true, + ); + } + } + + /// Disable the front-end's character device handlers. + pub fn disable_handlers(&self) { + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { + bindings::qemu_chr_fe_set_handlers( + addr_of_mut!(*chr), + None, + None, + None, + None, + core::ptr::null_mut(), + core::ptr::null_mut(), + true, + ); + } + } + + /// Notify that the frontend is ready to receive data. + pub fn accept_input(&self) { + let mut chr = self.inner.borrow_mut(); + // SAFETY: the borrow promises that the BQL is taken + unsafe { bindings::qemu_chr_fe_accept_input(addr_of_mut!(*chr)) } + } + + /// Temporarily borrow the character device, allowing it to be used + /// as an implementor of `Write`. Note that it is not valid to drop + /// the big QEMU lock while the character device is borrowed, as + /// that might cause C code to write to the character device. + pub fn borrow_mut(&self) -> impl Write + '_ { + CharBackendMut(self.inner.borrow_mut()) + } + + /// Send a continuous stream of zero bits on the line if `enabled` is + /// true, or a short stream if `enabled` is false. + pub fn send_break(&self, long: bool) -> io::Result<()> { + let mut chr = self.inner.borrow_mut(); + let mut duration: c_int = long.into(); + // SAFETY: the borrow promises that the BQL is taken + let r = unsafe { + bindings::qemu_chr_fe_ioctl( + addr_of_mut!(*chr), + bindings::CHR_IOCTL_SERIAL_SET_BREAK as i32, + addr_of_mut!(duration).cast::<c_void>(), + ) + }; + + errno::into_io_result(r).map(|_| ()) + } + + /// Write data to a character backend from the front end. This function + /// will send data from the front end to the back end. Unlike + /// `write`, this function will block if the back end cannot + /// consume all of the data attempted to be written. + /// + /// Returns the number of bytes consumed (0 if no associated Chardev) or an + /// error. + pub fn write(&self, buf: &[u8]) -> io::Result<usize> { + let len = buf.len().try_into().unwrap(); + // SAFETY: qemu_chr_fe_write is thread-safe + let r = unsafe { bindings::qemu_chr_fe_write(self.inner.as_ptr(), buf.as_ptr(), len) }; + errno::into_io_result(r).map(|cnt| cnt as usize) + } + + /// Write data to a character backend from the front end. This function + /// will send data from the front end to the back end. Unlike + /// `write`, this function will block if the back end cannot + /// consume all of the data attempted to be written. + /// + /// Returns the number of bytes consumed (0 if no associated Chardev) or an + /// error. + pub fn write_all(&self, buf: &[u8]) -> io::Result<()> { + let len = buf.len().try_into().unwrap(); + // SAFETY: qemu_chr_fe_write_all is thread-safe + let r = unsafe { bindings::qemu_chr_fe_write_all(self.inner.as_ptr(), buf.as_ptr(), len) }; + errno::into_io_result(r).and_then(|cnt| { + if cnt as usize == buf.len() { + Ok(()) + } else { + Err(ErrorKind::WriteZero.into()) + } + }) + } +} + +unsafe impl ObjectType for Chardev { + type Class = ChardevClass; + const TYPE_NAME: &'static CStr = + unsafe { CStr::from_bytes_with_nul_unchecked(bindings::TYPE_CHARDEV) }; +} +qom_isa!(Chardev: Object); diff --git a/rust/chardev/src/lib.rs b/rust/chardev/src/lib.rs new file mode 100644 index 0000000..2e549f9 --- /dev/null +++ b/rust/chardev/src/lib.rs @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +pub mod bindings; + +mod chardev; +pub use chardev::*; diff --git a/rust/chardev/wrapper.h b/rust/chardev/wrapper.h new file mode 100644 index 0000000..65ede6ea --- /dev/null +++ b/rust/chardev/wrapper.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +/* + * This header file is meant to be used as input to the `bindgen` application + * in order to generate C FFI compatible Rust bindings. + */ + +#ifndef __CLANG_STDATOMIC_H +#define __CLANG_STDATOMIC_H +/* + * Fix potential missing stdatomic.h error in case bindgen does not insert the + * correct libclang header paths on its own. We do not use stdatomic.h symbols + * in QEMU code, so it's fine to declare dummy types instead. + */ +typedef enum memory_order { + memory_order_relaxed, + memory_order_consume, + memory_order_acquire, + memory_order_release, + memory_order_acq_rel, + memory_order_seq_cst, +} memory_order; +#endif /* __CLANG_STDATOMIC_H */ + +#include "qemu/osdep.h" + +#include "chardev/char-fe.h" +#include "chardev/char-serial.h" |