extern crate libc;
mod error;
use libc::{c_int, c_void, size_t};
use std::alloc::{GlobalAlloc, Layout};
const GC_SUCCESS: c_int = 0;
#[repr(C)]
struct GcStackBase {
mem_base: *const c_void,
}
#[link(name = "gc", kind = "static")]
extern "C" {
fn GC_allow_register_threads() -> c_void;
fn GC_alloc_lock() -> c_void;
fn GC_alloc_unlock() -> c_void;
fn GC_free(ptr: *mut c_void);
fn GC_get_stack_base(stack_base: *mut GcStackBase) -> c_int;
fn GC_init() -> c_void;
fn GC_malloc(size: size_t) -> *mut c_void;
fn GC_register_my_thread(stack_base: *const GcStackBase) -> c_int;
fn GC_set_stackbottom(thread: *const c_void, stack_bottom: *const GcStackBase) -> c_void;
fn GC_unregister_my_thread() -> c_void;
}
pub struct Allocator;
impl Allocator {
pub fn lock() {
unsafe { GC_alloc_lock() };
}
pub fn unlock() {
unsafe { GC_alloc_unlock() };
}
pub unsafe fn initialize() {
GC_init();
GC_allow_register_threads();
}
pub unsafe fn register_current_thread() -> Result<(), error::Error> {
let mut base = GcStackBase {
mem_base: std::ptr::null(),
};
if GC_get_stack_base(&mut base) != GC_SUCCESS {
return Err(error::Error::new("failed to get stack base"));
} else if GC_register_my_thread(&base) != GC_SUCCESS {
return Err(error::Error::new("failed to register a thread for GC"));
}
Ok(())
}
pub unsafe fn set_stack_bottom(bottom: *const u8) {
GC_set_stackbottom(
std::ptr::null(),
&GcStackBase {
mem_base: bottom as *const libc::c_void,
},
);
}
pub unsafe fn unregister_current_thread() {
GC_unregister_my_thread();
}
}
unsafe impl GlobalAlloc for Allocator {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
GC_malloc(layout.size()) as *mut u8
}
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
GC_free(ptr as *mut c_void)
}
}