1 files changed, 42 insertions, 0 deletions
diff --git a/library/std/src/sys/wasi/alloc.rs b/library/std/src/sys/wasi/alloc.rs
new file mode 100644
index 00000000000..57187851a14
--- /dev/null
+++ b/library/std/src/sys/wasi/alloc.rs
@@ -0,0 +1,42 @@
+use crate::alloc::{GlobalAlloc, Layout, System};
+use crate::ptr;
+use crate::sys_common::alloc::{realloc_fallback, MIN_ALIGN};
+
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+unsafe impl GlobalAlloc for System {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+            libc::malloc(layout.size()) as *mut u8
+        } else {
+            libc::aligned_alloc(layout.align(), layout.size()) as *mut u8
+        }
+    }
+
+    #[inline]
+    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+            libc::calloc(layout.size(), 1) as *mut u8
+        } else {
+            let ptr = self.alloc(layout.clone());
+            if !ptr.is_null() {
+                ptr::write_bytes(ptr, 0, layout.size());
+            }
+            ptr
+        }
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        libc::free(ptr as *mut libc::c_void)
+    }
+
+    #[inline]
+    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
+            libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
+        } else {
+            realloc_fallback(self, ptr, layout, new_size)
+        }
+    }
+}