Use new nightly GlobalAlloc API

src/hole.rs

@@ -1,5 +1,6 @@
+use core::ptr::NonNull;
 use core::mem::size_of;
-use alloc::allocator::{Layout, AllocErr};
+use core::alloc::{Layout, Opaque, AllocErr};
 
 use super::align_up;
 
@@ -42,7 +43,7 @@ impl HoleList {
     /// block is returned.
     /// This function uses the “first fit” strategy, so it uses the first hole that is big
     /// enough. Thus the runtime is in O(n) but it should be reasonably fast for small allocations.
-    pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+    pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<NonNull<Opaque>, AllocErr> {
         assert!(layout.size() >= Self::min_size());
 
         allocate_first_fit(&mut self.first, layout).map(|allocation| {
@@ -52,7 +53,7 @@ impl HoleList {
             if let Some(padding) = allocation.back_padding {
                 deallocate(&mut self.first, padding.addr, padding.size);
             }
-            allocation.info.addr as *mut u8
+            NonNull::new(allocation.info.addr as *mut Opaque).unwrap()
         })
     }
 
@@ -62,8 +63,8 @@ impl HoleList {
     /// This function walks the list and inserts the given block at the correct place. If the freed
     /// block is adjacent to another free block, the blocks are merged again.
     /// This operation is in `O(n)` since the list needs to be sorted by address.
-    pub unsafe fn deallocate(&mut self, ptr: *mut u8, layout: Layout) {
-        deallocate(&mut self.first, ptr as usize, layout.size())
+    pub unsafe fn deallocate(&mut self, ptr: NonNull<Opaque>, layout: Layout) {
+        deallocate(&mut self.first, ptr.as_ptr() as usize, layout.size())
     }
 
     /// Returns the minimal allocation size. Smaller allocations or deallocations are not allowed.
@@ -199,7 +200,7 @@ fn allocate_first_fit(mut previous: &mut Hole, layout: Layout) -> Result<Allocat
             }
             None => {
                 // this was the last hole, so no hole is big enough -> allocation not possible
-                return Err(AllocErr::Exhausted { request: layout });
+                return Err(AllocErr);
             }
         }
     }

src/lib.rs

@@ -3,8 +3,6 @@
 #![feature(pointer_methods)]
 #![no_std]
 
-extern crate alloc;
-
 #[cfg(test)]
 #[macro_use]
 extern crate std;
@@ -14,9 +12,10 @@ extern crate spin;
 
 use hole::{Hole, HoleList};
 use core::mem;
+use core::ptr::NonNull;
 #[cfg(feature = "use_spin")]
 use core::ops::Deref;
-use alloc::allocator::{Alloc, Layout, AllocErr};
+use core::alloc::{Alloc, GlobalAlloc, AllocErr, Layout, Opaque};
 #[cfg(feature = "use_spin")]
 use spin::Mutex;
 
@@ -70,7 +69,7 @@ impl Heap {
     /// This function scans the list of free memory blocks and uses the first block that is big
     /// enough. The runtime is in O(n) where n is the number of free blocks, but it should be
     /// reasonably fast for small allocations.
-    pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+    pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<NonNull<Opaque>, AllocErr> {
         let mut size = layout.size();
         if size < HoleList::min_size() {
             size = HoleList::min_size();
@@ -88,7 +87,7 @@ impl Heap {
     /// This function walks the list of free memory blocks and inserts the freed block at the
     /// correct place. If the freed block is adjacent to another free block, the blocks are merged
     /// again. This operation is in `O(n)` since the list needs to be sorted by address.
-    pub unsafe fn deallocate(&mut self, ptr: *mut u8, layout: Layout) {
+    pub unsafe fn deallocate(&mut self, ptr: NonNull<Opaque>, layout: Layout) {
         let mut size = layout.size();
         if size < HoleList::min_size() {
             size = HoleList::min_size();
@@ -122,21 +121,21 @@ impl Heap {
     pub unsafe fn extend(&mut self, by: usize) {
         let top = self.top();
         let layout = Layout::from_size_align(by, 1).unwrap();
-        self.holes.deallocate(top as *mut u8, layout);
+        self.holes.deallocate(NonNull::new_unchecked(top as *mut Opaque), layout);
         self.size += by;
     }
 }
 
 unsafe impl Alloc for Heap {
-    unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+    unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<Opaque>, AllocErr> {
         self.allocate_first_fit(layout)
     }
 
-    unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+    unsafe fn dealloc(&mut self, ptr: NonNull<Opaque>, layout: Layout) {
         self.deallocate(ptr, layout)
     }
 
-    fn oom(&mut self, _: AllocErr) -> ! {
+    fn oom(&mut self) -> ! {
         panic!("Out of memory");
     }
 }
@@ -174,16 +173,18 @@ impl Deref for LockedHeap {
 }
 
 #[cfg(feature = "use_spin")]
-unsafe impl<'a> Alloc for &'a LockedHeap {
-    unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
-        self.0.lock().allocate_first_fit(layout)
+unsafe impl GlobalAlloc for LockedHeap {
+    unsafe fn alloc(&self, layout: Layout) -> *mut Opaque {
+        self.0.lock().allocate_first_fit(layout).ok().map_or(0 as *mut Opaque, |allocation| {
+            allocation.as_ptr()
+        })
     }
 
-    unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
-        self.0.lock().deallocate(ptr, layout)
+    unsafe fn dealloc(&self, ptr: *mut Opaque, layout: Layout) {
+        self.0.lock().deallocate(NonNull::new_unchecked(ptr), layout)
     }
 
-    fn oom(&mut self, _: AllocErr) -> ! {
+    fn oom(&self) -> ! {
         panic!("Out of memory");
     }
 }

src/test.rs

@@ -1,6 +1,6 @@
 use std::prelude::v1::*;
 use std::mem::{size_of, align_of};
-use alloc::allocator::Layout;
+use core::alloc::Layout;
 use super::*;
 
 fn new_heap() -> Heap {
@@ -46,7 +46,7 @@ fn allocate_double_usize() {
     let layout = Layout::from_size_align(size, align_of::<usize>());
     let addr = heap.allocate_first_fit(layout.unwrap());
     assert!(addr.is_ok());
-    let addr = addr.unwrap() as usize;
+    let addr = addr.unwrap().as_ptr() as usize;
     assert!(addr == heap.bottom);
     let (hole_addr, hole_size) = heap.holes.first_hole().expect("ERROR: no hole left");
     assert!(hole_addr == heap.bottom + size);
@@ -64,7 +64,7 @@ fn allocate_and_free_double_usize() {
     let layout = Layout::from_size_align(size_of::<usize>() * 2, align_of::<usize>()).unwrap();
     let x = heap.allocate_first_fit(layout.clone()).unwrap();
     unsafe {
-        *(x as *mut (usize, usize)) = (0xdeafdeadbeafbabe, 0xdeafdeadbeafbabe);
+        *(x.as_ptr() as *mut (usize, usize)) = (0xdeafdeadbeafbabe, 0xdeafdeadbeafbabe);
 
         heap.deallocate(x, layout.clone());
         assert_eq!((*(heap.bottom as *const Hole)).size, heap.size);
@@ -83,11 +83,11 @@ fn deallocate_right_before() {
 
     unsafe {
         heap.deallocate(y, layout.clone());
-        assert_eq!((*(y as *const Hole)).size, layout.size());
+        assert_eq!((*(y.as_ptr() as *const Hole)).size, layout.size());
         heap.deallocate(x, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, layout.size() * 2);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, layout.size() * 2);
         heap.deallocate(z, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, heap.size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, heap.size);
     }
 }
 
@@ -103,11 +103,11 @@ fn deallocate_right_behind() {
 
     unsafe {
         heap.deallocate(x, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, size);
         heap.deallocate(y, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, size * 2);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, size * 2);
         heap.deallocate(z, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, heap.size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, heap.size);
     }
 }
 
@@ -124,14 +124,14 @@ fn deallocate_middle() {
 
     unsafe {
         heap.deallocate(x, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, size);
         heap.deallocate(z, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, size);
-        assert_eq!((*(z as *const Hole)).size, size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, size);
+        assert_eq!((*(z.as_ptr() as *const Hole)).size, size);
         heap.deallocate(y, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, size * 3);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, size * 3);
         heap.deallocate(a, layout.clone());
-        assert_eq!((*(x as *const Hole)).size, heap.size);
+        assert_eq!((*(x.as_ptr() as *const Hole)).size, heap.size);
     }
 }
 
@@ -167,9 +167,9 @@ fn allocate_multiple_sizes() {
 
     let x = heap.allocate_first_fit(layout_1.clone()).unwrap();
     let y = heap.allocate_first_fit(layout_2.clone()).unwrap();
-    assert_eq!(y as usize, x as usize + base_size * 2);
+    assert_eq!(y.as_ptr() as usize, x.as_ptr() as usize + base_size * 2);
     let z = heap.allocate_first_fit(layout_3.clone()).unwrap();
-    assert_eq!(z as usize % (base_size * 4), 0);
+    assert_eq!(z.as_ptr() as usize % (base_size * 4), 0);
 
     unsafe {
         heap.deallocate(x, layout_1.clone());