src/liballoc_system/lib.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![crate_name = "alloc_system"]
  12 #![crate_type = "rlib"]
  13 #![no_std]
  14 #![allocator]
  15 #![deny(warnings)]
  16 #![unstable(feature = "alloc_system",
  17             reason = "this library is unlikely to be stabilized in its current \
  18                       form or name",
  19             issue = "27783")]
  20 #![feature(allocator)]
  21 #![feature(staged_api)]
  22 #![cfg_attr(any(unix, target_os = "redox"), feature(libc))]
  23
  24 // The minimum alignment guaranteed by the architecture. This value is used to
  25 // add fast paths for low alignment values. In practice, the alignment is a
  26 // constant at the call site and the branch will be optimized out.
  27 #[cfg(all(any(target_arch = "x86",
  28               target_arch = "arm",
  29               target_arch = "mips",
  30               target_arch = "powerpc",
  31               target_arch = "powerpc64",
  32               target_arch = "asmjs",
  33               target_arch = "wasm32")))]
  34 const MIN_ALIGN: usize = 8;
  35 #[cfg(all(any(target_arch = "x86_64",
  36               target_arch = "aarch64",
  37               target_arch = "mips64",
  38               target_arch = "s390x",
  39               target_arch = "sparc64")))]
  40 const MIN_ALIGN: usize = 16;
  41
  42 #[no_mangle]
  43 pub extern "C" fn __rust_allocate(size: usize, align: usize) -> *mut u8 {
  44     unsafe { imp::allocate(size, align) }
  45 }
  46
  47 #[no_mangle]
  48 pub extern "C" fn __rust_allocate_zeroed(size: usize, align: usize) -> *mut u8 {
  49     unsafe { imp::allocate_zeroed(size, align) }
  50 }
  51
  52 #[no_mangle]
  53 pub extern "C" fn __rust_deallocate(ptr: *mut u8, old_size: usize, align: usize) {
  54     unsafe { imp::deallocate(ptr, old_size, align) }
  55 }
  56
  57 #[no_mangle]
  58 pub extern "C" fn __rust_reallocate(ptr: *mut u8,
  59                                     old_size: usize,
  60                                     size: usize,
  61                                     align: usize)
  62                                     -> *mut u8 {
  63     unsafe { imp::reallocate(ptr, old_size, size, align) }
  64 }
  65
  66 #[no_mangle]
  67 pub extern "C" fn __rust_reallocate_inplace(ptr: *mut u8,
  68                                             old_size: usize,
  69                                             size: usize,
  70                                             align: usize)
  71                                             -> usize {
  72     unsafe { imp::reallocate_inplace(ptr, old_size, size, align) }
  73 }
  74
  75 #[no_mangle]
  76 pub extern "C" fn __rust_usable_size(size: usize, align: usize) -> usize {
  77     imp::usable_size(size, align)
  78 }
  79
  80 #[cfg(any(unix, target_os = "redox"))]
  81 mod imp {
  82     extern crate libc;
  83
  84     use core::cmp;
  85     use core::ptr;
  86     use MIN_ALIGN;
  87
  88     pub unsafe fn allocate(size: usize, align: usize) -> *mut u8 {
  89         if align <= MIN_ALIGN {
  90             libc::malloc(size as libc::size_t) as *mut u8
  91         } else {
  92             aligned_malloc(size, align)
  93         }
  94     }
  95
  96     #[cfg(any(target_os = "android", target_os = "redox"))]
  97     unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
  98         // On android we currently target API level 9 which unfortunately
  99         // doesn't have the `posix_memalign` API used below. Instead we use
 100         // `memalign`, but this unfortunately has the property on some systems
 101         // where the memory returned cannot be deallocated by `free`!
 102         //
 103         // Upon closer inspection, however, this appears to work just fine with
 104         // Android, so for this platform we should be fine to call `memalign`
 105         // (which is present in API level 9). Some helpful references could
 106         // possibly be chromium using memalign [1], attempts at documenting that
 107         // memalign + free is ok [2] [3], or the current source of chromium
 108         // which still uses memalign on android [4].
 109         //
 110         // [1]: https://codereview.chromium.org/10796020/
 111         // [2]: https://code.google.com/p/android/issues/detail?id=35391
 112         // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
 113         // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
 114         //                                       /memory/aligned_memory.cc
 115         libc::memalign(align as libc::size_t, size as libc::size_t) as *mut u8
 116     }
 117
 118     #[cfg(not(any(target_os = "android", target_os = "redox")))]
 119     unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
 120         let mut out = ptr::null_mut();
 121         let ret = libc::posix_memalign(&mut out, align as libc::size_t, size as libc::size_t);
 122         if ret != 0 {
 123             ptr::null_mut()
 124         } else {
 125             out as *mut u8
 126         }
 127     }
 128
 129     pub unsafe fn allocate_zeroed(size: usize, align: usize) -> *mut u8 {
 130         if align <= MIN_ALIGN {
 131             libc::calloc(size as libc::size_t, 1) as *mut u8
 132         } else {
 133             let ptr = aligned_malloc(size, align);
 134             if !ptr.is_null() {
 135                 ptr::write_bytes(ptr, 0, size);
 136             }
 137             ptr
 138         }
 139     }
 140
 141     pub unsafe fn reallocate(ptr: *mut u8, old_size: usize, size: usize, align: usize) -> *mut u8 {
 142         if align <= MIN_ALIGN {
 143             libc::realloc(ptr as *mut libc::c_void, size as libc::size_t) as *mut u8
 144         } else {
 145             let new_ptr = allocate(size, align);
 146             if !new_ptr.is_null() {
 147                 ptr::copy(ptr, new_ptr, cmp::min(size, old_size));
 148                 deallocate(ptr, old_size, align);
 149             }
 150             new_ptr
 151         }
 152     }
 153
 154     pub unsafe fn reallocate_inplace(_ptr: *mut u8,
 155                                      old_size: usize,
 156                                      _size: usize,
 157                                      _align: usize)
 158                                      -> usize {
 159         old_size
 160     }
 161
 162     pub unsafe fn deallocate(ptr: *mut u8, _old_size: usize, _align: usize) {
 163         libc::free(ptr as *mut libc::c_void)
 164     }
 165
 166     pub fn usable_size(size: usize, _align: usize) -> usize {
 167         size
 168     }
 169 }
 170
 171 #[cfg(windows)]
 172 #[allow(bad_style)]
 173 mod imp {
 174     use MIN_ALIGN;
 175
 176     type LPVOID = *mut u8;
 177     type HANDLE = LPVOID;
 178     type SIZE_T = usize;
 179     type DWORD = u32;
 180     type BOOL = i32;
 181
 182     extern "system" {
 183         fn GetProcessHeap() -> HANDLE;
 184         fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
 185         fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
 186         fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
 187         fn GetLastError() -> DWORD;
 188     }
 189
 190     #[repr(C)]
 191     struct Header(*mut u8);
 192
 193
 194     const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
 195     const HEAP_REALLOC_IN_PLACE_ONLY: DWORD = 0x00000010;
 196
 197     unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
 198         &mut *(ptr as *mut Header).offset(-1)
 199     }
 200
 201     unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
 202         let aligned = ptr.offset((align - (ptr as usize & (align - 1))) as isize);
 203         *get_header(aligned) = Header(ptr);
 204         aligned
 205     }
 206
 207     #[inline]
 208     unsafe fn allocate_with_flags(size: usize, align: usize, flags: DWORD) -> *mut u8 {
 209         if align <= MIN_ALIGN {
 210             HeapAlloc(GetProcessHeap(), flags, size as SIZE_T) as *mut u8
 211         } else {
 212             let ptr = HeapAlloc(GetProcessHeap(), flags, (size + align) as SIZE_T) as *mut u8;
 213             if ptr.is_null() {
 214                 return ptr;
 215             }
 216             align_ptr(ptr, align)
 217         }
 218     }
 219
 220     pub unsafe fn allocate(size: usize, align: usize) -> *mut u8 {
 221         allocate_with_flags(size, align, 0)
 222     }
 223
 224     pub unsafe fn allocate_zeroed(size: usize, align: usize) -> *mut u8 {
 225         allocate_with_flags(size, align, HEAP_ZERO_MEMORY)
 226     }
 227
 228     pub unsafe fn reallocate(ptr: *mut u8, _old_size: usize, size: usize, align: usize) -> *mut u8 {
 229         if align <= MIN_ALIGN {
 230             HeapReAlloc(GetProcessHeap(), 0, ptr as LPVOID, size as SIZE_T) as *mut u8
 231         } else {
 232             let header = get_header(ptr);
 233             let new = HeapReAlloc(GetProcessHeap(),
 234                                   0,
 235                                   header.0 as LPVOID,
 236                                   (size + align) as SIZE_T) as *mut u8;
 237             if new.is_null() {
 238                 return new;
 239             }
 240             align_ptr(new, align)
 241         }
 242     }
 243
 244     pub unsafe fn reallocate_inplace(ptr: *mut u8,
 245                                      old_size: usize,
 246                                      size: usize,
 247                                      align: usize)
 248                                      -> usize {
 249         if align <= MIN_ALIGN {
 250             let new = HeapReAlloc(GetProcessHeap(),
 251                                   HEAP_REALLOC_IN_PLACE_ONLY,
 252                                   ptr as LPVOID,
 253                                   size as SIZE_T) as *mut u8;
 254             if new.is_null() { old_size } else { size }
 255         } else {
 256             old_size
 257         }
 258     }
 259
 260     pub unsafe fn deallocate(ptr: *mut u8, _old_size: usize, align: usize) {
 261         if align <= MIN_ALIGN {
 262             let err = HeapFree(GetProcessHeap(), 0, ptr as LPVOID);
 263             debug_assert!(err != 0, "Failed to free heap memory: {}", GetLastError());
 264         } else {
 265             let header = get_header(ptr);
 266             let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
 267             debug_assert!(err != 0, "Failed to free heap memory: {}", GetLastError());
 268         }
 269     }
 270
 271     pub fn usable_size(size: usize, _align: usize) -> usize {
 272         size
 273     }
 274 }