Merge pull request #36 from rustwasm/no-mmap-alloc-crate

Use `libc::mmap` directly again, instead of `mmap-alloc` crate

Author: fitzgen

wee_alloc/Cargo.toml

@@ -32,11 +32,6 @@ unreachable = "1.0.0"
 default-features = false
 version = "0.2"
 
-[target.'cfg(any(target_os = "linux", target_os = "macos"))'.dependencies.mmap-alloc]
-version = "0.2"
-git = "https://github.com/fitzgen/allocators-rs"
-branch = "new-alloc-api"
-
 [target.'cfg(target_os = "windows")'.dependencies.winapi]
 version = "0.3"
 features = ["memoryapi", "synchapi", "winbase"]

wee_alloc/src/imp_unix.rs

@@ -1,20 +1,26 @@
-use alloc::allocator::{Alloc, Layout};
 use const_init::ConstInit;
 use core::alloc::{AllocErr, Opaque};
 use core::cell::UnsafeCell;
 use core::ptr::NonNull;
 use libc;
-use mmap_alloc::MapAllocBuilder;
 use memory_units::{Bytes, Pages};
 
 pub(crate) fn alloc_pages(pages: Pages) -> Result<NonNull<Opaque>, AllocErr> {
     unsafe {
         let bytes: Bytes = pages.into();
-        let layout = Layout::from_size_align_unchecked(bytes.0, 1);
-
-        MapAllocBuilder::default()
-            .build()
-            .alloc(layout)
+        let addr = libc::mmap(
+            0 as *mut _,
+            bytes.0,
+            libc::PROT_WRITE | libc::PROT_READ,
+            libc::MAP_ANON | libc::MAP_PRIVATE,
+            -1,
+            0,
+        );
+        if addr == libc::MAP_FAILED {
+            Err(AllocErr)
+        } else {
+            NonNull::new(addr as *mut Opaque).ok_or(AllocErr)
+        }
     }
 }
 

wee_alloc/src/lib.rs

@@ -237,7 +237,6 @@ cfg_if! {
         use imp_wasm32 as imp;
     } else if #[cfg(unix)] {
         extern crate libc;
-        extern crate mmap_alloc;
         mod imp_unix;
         use imp_unix as imp;
     } else if #[cfg(windows)] {

wee_alloc/src/neighbors.rs

@@ -59,6 +59,7 @@ where
 
     #[test]
     fn can_use_low_bits() {
+        use core::mem;
         assert!(
             mem::align_of::<*const u8>() >= 0b100,
             "we rely on being able to stick tags into the lowest two bits"