sys crate (#583)

Fix #508.

bdwgc-alloc/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "bdwgc-alloc"
+version.workspace = true
+edition.workspace = true
+description = "impl GlobalAlloc for bdwgc"
+documentation = "https://bdwgc.github.io/bdwgc-rust/bdwgc_alloc/"
+repository.workspace = true
+license.workspace = true
+categories = ["api-bindings", "memory-management", "no-std", "no-std::no-alloc"]
+
+[dependencies]
+bdwgc-alloc-sys = { version = "0.6.15", path = "../bdwgc-alloc-sys", default-features = false }
+
+[features]
+default = ["autotools"]
+autotools = ["bdwgc-alloc-sys/autotools"]
+cmake = ["bdwgc-alloc-sys/cmake"]
+
+[lints]
+workspace = true

bdwgc-alloc/README.md

@@ -0,0 +1 @@
+../README.md

bdwgc-alloc/src/error.rs

@@ -0,0 +1,27 @@
+use core::{
+    error,
+    fmt::{self, Display, Formatter},
+};
+
+#[derive(Debug)]
+pub struct Error {
+    description: &'static str,
+}
+
+impl Error {
+    pub const fn new(description: &'static str) -> Error {
+        Error { description }
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, formatter: &mut Formatter) -> fmt::Result {
+        write!(formatter, "{}", self.description)
+    }
+}
+
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        self.description
+    }
+}

bdwgc-alloc/src/lib.rs

@@ -0,0 +1,129 @@
+#![doc = include_str!("../README.md")]
+#![no_std]
+
+mod error;
+
+use bdwgc_alloc_sys::{
+    GC_SUCCESS, GC_alloc_lock, GC_alloc_unlock, GC_allow_register_threads, GC_free, GC_gcollect,
+    GC_get_stack_base, GC_init, GC_malloc, GC_realloc, GC_register_finalizer,
+    GC_register_my_thread, GC_set_stackbottom, GC_stack_base, GC_unregister_my_thread,
+};
+use core::{
+    alloc::{GlobalAlloc, Layout},
+    ffi::c_void,
+    ptr::null_mut,
+};
+
+/// An allocator.
+pub struct Allocator;
+
+impl Allocator {
+    /// Locks a collector.
+    pub fn lock() {
+        unsafe { GC_alloc_lock() }
+    }
+
+    /// Unlocks a collector.
+    pub fn unlock() {
+        unsafe { GC_alloc_unlock() }
+    }
+
+    /// Initializes a collector.
+    ///
+    /// # Safety
+    ///
+    /// This function must be called in a main thread.
+    pub unsafe fn initialize() {
+        unsafe {
+            GC_init();
+            GC_allow_register_threads();
+        }
+    }
+
+    /// Registers a current thread to a collector.
+    ///
+    /// # Safety
+    ///
+    /// This function must not be called in a main thread.
+    pub unsafe fn register_current_thread() -> Result<(), error::Error> {
+        let mut base = GC_stack_base {
+            mem_base: null_mut(),
+        };
+
+        if unsafe { GC_get_stack_base(&mut base) } != GC_SUCCESS {
+            return Err(error::Error::new("failed to get stack base"));
+        } else if unsafe { GC_register_my_thread(&base) } != GC_SUCCESS {
+            return Err(error::Error::new("failed to register a thread for GC"));
+        }
+
+        Ok(())
+    }
+
+    /// Sets a bottom of a stack.
+    ///
+    /// You do not have to call this function in most cases.
+    /// A collector detects the bottom on initialization automatically.
+    ///
+    /// # Safety
+    ///
+    /// The bottom address must be valid.
+    pub unsafe fn set_stack_bottom(bottom: *const u8) {
+        unsafe {
+            GC_set_stackbottom(
+                null_mut(),
+                &GC_stack_base {
+                    mem_base: bottom.cast_mut().cast(),
+                },
+            )
+        }
+    }
+
+    /// Unregisters a current thread from a collector.
+    ///
+    /// # Safety
+    ///
+    /// The thread must be registered already.
+    pub unsafe fn unregister_current_thread() {
+        unsafe { GC_unregister_my_thread() };
+    }
+
+    /// Runs a garbage collection forcibly.
+    pub fn force_collect() {
+        unsafe { GC_gcollect() }
+    }
+
+    /// Registers a finalizer of an object.
+    ///
+    /// # Safety
+    ///
+    /// The given finalizer must not be null and handle pointers properly.
+    pub unsafe fn register_finalizer(
+        ptr: *const c_void,
+        finalizer: extern "C" fn(*mut c_void, *mut c_void),
+        client_data: *const c_void,
+    ) {
+        unsafe {
+            GC_register_finalizer(
+                ptr.cast_mut(),
+                Some(finalizer),
+                client_data.cast_mut(),
+                null_mut(),
+                null_mut(),
+            )
+        };
+    }
+}
+
+unsafe impl GlobalAlloc for Allocator {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        (unsafe { GC_malloc(layout.size()) }) as *mut u8
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        unsafe { GC_free(ptr as *mut c_void) }
+    }
+
+    unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, size: usize) -> *mut u8 {
+        (unsafe { GC_realloc(ptr as *mut c_void, size) }) as *mut u8
+    }
+}