1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249
//! Memory allocation APIs #![stable(feature = "alloc_module", since = "1.28.0")] use core::intrinsics::{min_align_of_val, size_of_val}; use core::ptr::{NonNull, Unique}; use core::usize; #[stable(feature = "alloc_module", since = "1.28.0")] #[doc(inline)] pub use core::alloc::*; #[cfg(test)] mod tests; extern "Rust" { // These are the magic symbols to call the global allocator. rustc generates // them from the `#[global_allocator]` attribute if there is one, or uses the // default implementations in libstd (`__rdl_alloc` etc in `src/libstd/alloc.rs`) // otherwise. #[rustc_allocator] #[rustc_allocator_nounwind] fn __rust_alloc(size: usize, align: usize) -> *mut u8; #[rustc_allocator_nounwind] fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize); #[rustc_allocator_nounwind] fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8; #[rustc_allocator_nounwind] fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8; } /// The global memory allocator. /// /// This type implements the [`Alloc`] trait by forwarding calls /// to the allocator registered with the `#[global_allocator]` attribute /// if there is one, or the `std` crate’s default. /// /// Note: while this type is unstable, the functionality it provides can be /// accessed through the [free functions in `alloc`](index.html#functions). /// /// [`Alloc`]: trait.Alloc.html #[unstable(feature = "allocator_api", issue = "32838")] #[derive(Copy, Clone, Default, Debug)] pub struct Global; /// Allocate memory with the global allocator. /// /// This function forwards calls to the [`GlobalAlloc::alloc`] method /// of the allocator registered with the `#[global_allocator]` attribute /// if there is one, or the `std` crate’s default. /// /// This function is expected to be deprecated in favor of the `alloc` method /// of the [`Global`] type when it and the [`Alloc`] trait become stable. /// /// # Safety /// /// See [`GlobalAlloc::alloc`]. /// /// [`Global`]: struct.Global.html /// [`Alloc`]: trait.Alloc.html /// [`GlobalAlloc::alloc`]: trait.GlobalAlloc.html#tymethod.alloc /// /// # Examples /// /// ``` /// use std::alloc::{alloc, dealloc, Layout}; /// /// unsafe { /// let layout = Layout::new::<u16>(); /// let ptr = alloc(layout); /// /// *(ptr as *mut u16) = 42; /// assert_eq!(*(ptr as *mut u16), 42); /// /// dealloc(ptr, layout); /// } /// ``` #[stable(feature = "global_alloc", since = "1.28.0")] #[inline] pub unsafe fn alloc(layout: Layout) -> *mut u8 { __rust_alloc(layout.size(), layout.align()) } /// Deallocate memory with the global allocator. /// /// This function forwards calls to the [`GlobalAlloc::dealloc`] method /// of the allocator registered with the `#[global_allocator]` attribute /// if there is one, or the `std` crate’s default. /// /// This function is expected to be deprecated in favor of the `dealloc` method /// of the [`Global`] type when it and the [`Alloc`] trait become stable. /// /// # Safety /// /// See [`GlobalAlloc::dealloc`]. /// /// [`Global`]: struct.Global.html /// [`Alloc`]: trait.Alloc.html /// [`GlobalAlloc::dealloc`]: trait.GlobalAlloc.html#tymethod.dealloc #[stable(feature = "global_alloc", since = "1.28.0")] #[inline] pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { __rust_dealloc(ptr, layout.size(), layout.align()) } /// Reallocate memory with the global allocator. /// /// This function forwards calls to the [`GlobalAlloc::realloc`] method /// of the allocator registered with the `#[global_allocator]` attribute /// if there is one, or the `std` crate’s default. /// /// This function is expected to be deprecated in favor of the `realloc` method /// of the [`Global`] type when it and the [`Alloc`] trait become stable. /// /// # Safety /// /// See [`GlobalAlloc::realloc`]. /// /// [`Global`]: struct.Global.html /// [`Alloc`]: trait.Alloc.html /// [`GlobalAlloc::realloc`]: trait.GlobalAlloc.html#method.realloc #[stable(feature = "global_alloc", since = "1.28.0")] #[inline] pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { __rust_realloc(ptr, layout.size(), layout.align(), new_size) } /// Allocate zero-initialized memory with the global allocator. /// /// This function forwards calls to the [`GlobalAlloc::alloc_zeroed`] method /// of the allocator registered with the `#[global_allocator]` attribute /// if there is one, or the `std` crate’s default. /// /// This function is expected to be deprecated in favor of the `alloc_zeroed` method /// of the [`Global`] type when it and the [`Alloc`] trait become stable. /// /// # Safety /// /// See [`GlobalAlloc::alloc_zeroed`]. /// /// [`Global`]: struct.Global.html /// [`Alloc`]: trait.Alloc.html /// [`GlobalAlloc::alloc_zeroed`]: trait.GlobalAlloc.html#method.alloc_zeroed /// /// # Examples /// /// ``` /// use std::alloc::{alloc_zeroed, dealloc, Layout}; /// /// unsafe { /// let layout = Layout::new::<u16>(); /// let ptr = alloc_zeroed(layout); /// /// assert_eq!(*(ptr as *mut u16), 0); /// /// dealloc(ptr, layout); /// } /// ``` #[stable(feature = "global_alloc", since = "1.28.0")] #[inline] pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { __rust_alloc_zeroed(layout.size(), layout.align()) } #[unstable(feature = "allocator_api", issue = "32838")] unsafe impl Alloc for Global { #[inline] unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> { NonNull::new(alloc(layout)).ok_or(AllocErr) } #[inline] unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) { dealloc(ptr.as_ptr(), layout) } #[inline] unsafe fn realloc(&mut self, ptr: NonNull<u8>, layout: Layout, new_size: usize) -> Result<NonNull<u8>, AllocErr> { NonNull::new(realloc(ptr.as_ptr(), layout, new_size)).ok_or(AllocErr) } #[inline] unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> { NonNull::new(alloc_zeroed(layout)).ok_or(AllocErr) } } /// The allocator for unique pointers. // This function must not unwind. If it does, MIR codegen will fail. #[cfg(not(test))] #[lang = "exchange_malloc"] #[inline] unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 { if size == 0 { align as *mut u8 } else { let layout = Layout::from_size_align_unchecked(size, align); let ptr = alloc(layout); if !ptr.is_null() { ptr } else { handle_alloc_error(layout) } } } #[cfg_attr(not(test), lang = "box_free")] #[inline] pub(crate) unsafe fn box_free<T: ?Sized>(ptr: Unique<T>) { let ptr = ptr.as_ptr(); let size = size_of_val(&*ptr); let align = min_align_of_val(&*ptr); // We do not allocate for Box<T> when T is ZST, so deallocation is also not necessary. if size != 0 { let layout = Layout::from_size_align_unchecked(size, align); dealloc(ptr as *mut u8, layout); } } /// Abort on memory allocation error or failure. /// /// Callers of memory allocation APIs wishing to abort computation /// in response to an allocation error are encouraged to call this function, /// rather than directly invoking `panic!` or similar. /// /// The default behavior of this function is to print a message to standard error /// and abort the process. /// It can be replaced with [`set_alloc_error_hook`] and [`take_alloc_error_hook`]. /// /// [`set_alloc_error_hook`]: ../../std/alloc/fn.set_alloc_error_hook.html /// [`take_alloc_error_hook`]: ../../std/alloc/fn.take_alloc_error_hook.html #[stable(feature = "global_alloc", since = "1.28.0")] #[rustc_allocator_nounwind] pub fn handle_alloc_error(layout: Layout) -> ! { #[cfg_attr(bootstrap, allow(improper_ctypes))] extern "Rust" { #[lang = "oom"] fn oom_impl(layout: Layout) -> !; } unsafe { oom_impl(layout) } }