std: Refactor liballoc out of lib{std,sync}

This commit is part of the libstd facade RFC, issue #13851. This creates a new
library, liballoc, which is intended to be the core allocation library for all
of Rust. It is pinned on the basic assumption that an allocation failure is an
abort or failure.

This module has inherited the heap/libc_heap modules from std::rt, the owned/rc
modules from std, and the arc module from libsync. These three pointers are
currently the three most core pointer implementations in Rust.

The UnsafeArc type in std::sync should be considered deprecated and replaced by
Arc<Unsafe<T>>. This commit does not currently migrate to this type, but future
commits will continue this refactoring.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/liballoc/libc_heap.rs b/src/liballoc/libc_heap.rs
new file mode 100644
index 00000000000..5b189bc672e
--- /dev/null
+++ b/src/liballoc/libc_heap.rs
@@ -0,0 +1,51 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+
+//! The global (exchange) heap.
+
+use libc::{c_void, size_t, free, malloc, realloc};
+use core::ptr::{RawPtr, mut_null};
+use core::intrinsics::abort;
+
+/// A wrapper around libc::malloc, aborting on out-of-memory
+#[inline]
+pub unsafe fn malloc_raw(size: uint) -> *mut u8 {
+    // `malloc(0)` may allocate, but it may also return a null pointer
+    // http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html
+    if size == 0 {
+        mut_null()
+    } else {
+        let p = malloc(size as size_t);
+        if p.is_null() {
+            // we need a non-allocating way to print an error here
+            abort();
+        }
+        p as *mut u8
+    }
+}
+
+/// A wrapper around libc::realloc, aborting on out-of-memory
+#[inline]
+pub unsafe fn realloc_raw(ptr: *mut u8, size: uint) -> *mut u8 {
+    // `realloc(ptr, 0)` may allocate, but it may also return a null pointer
+    // http://pubs.opengroup.org/onlinepubs/9699919799/functions/realloc.html
+    if size == 0 {
+        free(ptr as *mut c_void);
+        mut_null()
+    } else {
+        let p = realloc(ptr as *mut c_void, size as size_t);
+        if p.is_null() {
+            // we need a non-allocating way to print an error here
+            abort();
+        }
+        p as *mut u8
+    }
+}