This allows CStr constants to be defined easily on Rust 1.63.0, while
checking that there are no embedded NULs. c"" literals were only
stabilized in Rust 1.77.0.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
rust/hw/char/pl011/src/device.rs | 5 ++-
rust/hw/char/pl011/src/device_class.rs | 5 ++-
rust/hw/char/pl011/src/lib.rs | 4 +-
rust/qemu-api/meson.build | 4 ++
rust/qemu-api/src/c_str.rs | 53 ++++++++++++++++++++++++++
rust/qemu-api/src/lib.rs | 1 +
rust/qemu-api/tests/tests.rs | 8 ++--
7 files changed, 71 insertions(+), 9 deletions(-)
create mode 100644 rust/qemu-api/src/c_str.rs
diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs
index 7be21769ae4..5ffe1911376 100644
--- a/rust/hw/char/pl011/src/device.rs
+++ b/rust/hw/char/pl011/src/device.rs
@@ -11,6 +11,7 @@
use qemu_api::{
bindings::{self, *},
+ c_str,
definitions::ObjectImpl,
};
@@ -99,7 +100,7 @@ impl qemu_api::definitions::Class for PL011Class {
}
#[used]
-pub static CLK_NAME: &CStr = c"clk";
+pub static CLK_NAME: &CStr = c_str!("clk");
impl PL011State {
/// Initializes a pre-allocated, unitialized instance of `PL011State`.
@@ -575,7 +576,7 @@ pub fn update(&self) {
let dev: *mut DeviceState = qdev_new(PL011State::TYPE_INFO.name);
let sysbus: *mut SysBusDevice = dev.cast::<SysBusDevice>();
- qdev_prop_set_chr(dev, c"chardev".as_ptr(), chr);
+ qdev_prop_set_chr(dev, c_str!("chardev").as_ptr(), chr);
sysbus_realize_and_unref(sysbus, addr_of!(error_fatal) as *mut *mut Error);
sysbus_mmio_map(sysbus, 0, addr);
sysbus_connect_irq(sysbus, 0, irq);
diff --git a/rust/hw/char/pl011/src/device_class.rs b/rust/hw/char/pl011/src/device_class.rs
index 78fa1cdd5b6..3b9b0267b4c 100644
--- a/rust/hw/char/pl011/src/device_class.rs
+++ b/rust/hw/char/pl011/src/device_class.rs
@@ -6,6 +6,7 @@
use qemu_api::{
bindings::*,
+ c_str,
definitions::ObjectImpl,
zeroable::Zeroable,
};
@@ -22,14 +23,14 @@
qemu_api::declare_properties! {
PL011_PROPERTIES,
qemu_api::define_property!(
- c"chardev",
+ c_str!("chardev"),
PL011State,
char_backend,
unsafe { &qdev_prop_chr },
CharBackend
),
qemu_api::define_property!(
- c"migrate-clk",
+ c_str!("migrate-clk"),
PL011State,
migrate_clock,
unsafe { &qdev_prop_bool },
diff --git a/rust/hw/char/pl011/src/lib.rs b/rust/hw/char/pl011/src/lib.rs
index 2b157868b0f..0a598e5629d 100644
--- a/rust/hw/char/pl011/src/lib.rs
+++ b/rust/hw/char/pl011/src/lib.rs
@@ -41,11 +41,13 @@
extern crate bilge_impl;
extern crate qemu_api;
+use qemu_api::c_str;
+
pub mod device;
pub mod device_class;
pub mod memory_ops;
-pub const TYPE_PL011: &::std::ffi::CStr = c"pl011";
+pub const TYPE_PL011: &::std::ffi::CStr = c_str!("pl011");
/// Offset of each register from the base memory address of the device.
///
diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build
index 1b0fd406378..2b3dea59fb6 100644
--- a/rust/qemu-api/meson.build
+++ b/rust/qemu-api/meson.build
@@ -3,6 +3,7 @@ _qemu_api_rs = static_library(
structured_sources(
[
'src/lib.rs',
+ 'src/c_str.rs',
'src/definitions.rs',
'src/device_class.rs',
'src/zeroable.rs',
@@ -17,6 +18,9 @@ _qemu_api_rs = static_library(
],
)
+rust.test('rust-qemu-api-tests', _qemu_api_rs,
+ suite: ['unit', 'rust'])
+
qemu_api = declare_dependency(
link_with: _qemu_api_rs,
dependencies: qemu_api_macros,
diff --git a/rust/qemu-api/src/c_str.rs b/rust/qemu-api/src/c_str.rs
new file mode 100644
index 00000000000..5ef46d12bef
--- /dev/null
+++ b/rust/qemu-api/src/c_str.rs
@@ -0,0 +1,53 @@
+// Copyright 2024 Red Hat, Inc.
+// Author(s): Paolo Bonzini <pbonzini@redhat.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#[macro_export]
+/// Given a string constant _without_ embedded or trailing NULs, return
+/// a CStr.
+///
+/// Needed for compatibility with Rust <1.77.
+macro_rules! c_str {
+ ($str:expr) => {{
+ const STRING: &str = concat!($str, "\0");
+ const BYTES: &[u8] = STRING.as_bytes();
+
+ // "for" is not allowed in const context... oh well,
+ // everybody loves some lisp. This could be turned into
+ // a procedural macro if this is a problem; alternatively
+ // Rust 1.72 makes CStr::from_bytes_with_nul a const function.
+ const fn f(b: &[u8], i: usize) {
+ if i == BYTES.len() - 1 {
+ } else if BYTES[i] == 0 {
+ panic!("c_str argument contains NUL")
+ } else {
+ f(b, i + 1)
+ }
+ }
+ f(BYTES, 0);
+
+ // SAFETY: absence of NULs apart from the final byte was checked above
+ unsafe { std::ffi::CStr::from_bytes_with_nul_unchecked(BYTES) }
+ }};
+}
+
+#[cfg(test)]
+mod tests {
+ use std::ffi::CStr;
+
+ use crate::c_str;
+
+ #[test]
+ fn test_cstr_macro() {
+ let good = c_str!("🦀");
+ let good_bytes = b"\xf0\x9f\xa6\x80\0";
+ assert_eq!(good.to_bytes_with_nul(), good_bytes);
+ }
+
+ #[test]
+ fn test_cstr_macro_const() {
+ const GOOD: &CStr = c_str!("🦀");
+ const GOOD_BYTES: &[u8] = b"\xf0\x9f\xa6\x80\0";
+ assert_eq!(GOOD.to_bytes_with_nul(), GOOD_BYTES);
+ }
+}
diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs
index 321c33d2c7b..9c3be4f6489 100644
--- a/rust/qemu-api/src/lib.rs
+++ b/rust/qemu-api/src/lib.rs
@@ -27,6 +27,7 @@ unsafe impl Sync for bindings::Property {}
unsafe impl Sync for bindings::TypeInfo {}
unsafe impl Sync for bindings::VMStateDescription {}
+pub mod c_str;
pub mod definitions;
pub mod device_class;
pub mod zeroable;
diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs
index 3396c33fe1e..605bc99ed4c 100644
--- a/rust/qemu-api/tests/tests.rs
+++ b/rust/qemu-api/tests/tests.rs
@@ -6,7 +6,7 @@
use qemu_api::{
bindings::*,
- declare_properties, define_property,
+ c_str, declare_properties, define_property,
definitions::{Class, ObjectImpl},
device_class_init, vm_state_description,
};
@@ -16,7 +16,7 @@ fn test_device_decl_macros() {
// Test that macros can compile.
vm_state_description! {
VMSTATE,
- name: c"name",
+ name: c_str!("name"),
unmigratable: true,
}
@@ -35,7 +35,7 @@ pub struct DummyClass {
declare_properties! {
DUMMY_PROPERTIES,
define_property!(
- c"migrate-clk",
+ c_str!("migrate-clk"),
DummyState,
migrate_clock,
unsafe { &qdev_prop_bool },
@@ -54,7 +54,7 @@ pub struct DummyClass {
impl ObjectImpl for DummyState {
type Class = DummyClass;
const TYPE_INFO: qemu_api::bindings::TypeInfo = qemu_api::type_info! { Self };
- const TYPE_NAME: &'static CStr = c"dummy";
+ const TYPE_NAME: &'static CStr = c_str!("dummy");
const PARENT_TYPE_NAME: Option<&'static CStr> = Some(TYPE_DEVICE);
const ABSTRACT: bool = false;
const INSTANCE_INIT: Option<unsafe extern "C" fn(obj: *mut Object)> = None;
--
2.46.2