blob: e17238a91b1bbddd2056135a86bb5fc13c9753a9 [file] [log] [blame]
// Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// TODO(https://dartbug.com/44621): Remove this copy when package:ffi can be
// rolled. We need to wait until the `Allocator` interface has rolled into
// Flutter.
import 'dart:ffi';
import 'dart:io';
final DynamicLibrary stdlib = Platform.isWindows
? DynamicLibrary.open('kernel32.dll')
: DynamicLibrary.process();
typedef PosixCallocNative = Pointer Function(IntPtr num, IntPtr size);
typedef PosixCalloc = Pointer Function(int num, int size);
final PosixCalloc posixCalloc =
stdlib.lookupFunction<PosixCallocNative, PosixCalloc>('calloc');
typedef PosixFreeNative = Void Function(Pointer);
typedef PosixFree = void Function(Pointer);
final PosixFree posixFree =
stdlib.lookupFunction<PosixFreeNative, PosixFree>('free');
typedef WinGetProcessHeapFn = Pointer Function();
final WinGetProcessHeapFn winGetProcessHeap = stdlib
.lookupFunction<WinGetProcessHeapFn, WinGetProcessHeapFn>('GetProcessHeap');
final Pointer processHeap = winGetProcessHeap();
typedef WinHeapAllocNative = Pointer Function(Pointer, Uint32, IntPtr);
typedef WinHeapAlloc = Pointer Function(Pointer, int, int);
final WinHeapAlloc winHeapAlloc =
stdlib.lookupFunction<WinHeapAllocNative, WinHeapAlloc>('HeapAlloc');
typedef WinHeapFreeNative = Int32 Function(
Pointer heap, Uint32 flags, Pointer memory);
typedef WinHeapFree = int Function(Pointer heap, int flags, Pointer memory);
final WinHeapFree winHeapFree =
stdlib.lookupFunction<WinHeapFreeNative, WinHeapFree>('HeapFree');
const int HEAP_ZERO_MEMORY = 8;
/// Manages memory on the native heap.
///
/// Initializes newly allocated memory to zero.
///
/// For POSIX-based systems, this uses `calloc` and `free`. On Windows, it uses
/// `HeapAlloc` with [HEAP_ZERO_MEMORY] and `HeapFree` against the default
/// public heap.
class _CallocAllocator implements Allocator {
const _CallocAllocator();
/// Allocates [byteCount] bytes of zero-initialized of memory on the native
/// heap.
///
/// For POSIX-based systems, this uses `calloc`. On Windows, it uses
/// `HeapAlloc` against the default public heap.
///
/// Throws an [ArgumentError] if the number of bytes or alignment cannot be
/// satisfied.
// TODO: Stop ignoring alignment if it's large, for example for SSE data.
@override
Pointer<T> allocate<T extends NativeType>(int byteCount, {int? alignment}) {
Pointer<T> result;
if (Platform.isWindows) {
result = winHeapAlloc(processHeap, /*flags=*/ HEAP_ZERO_MEMORY, byteCount)
.cast();
} else {
result = posixCalloc(byteCount, 1).cast();
}
if (result.address == 0) {
throw ArgumentError('Could not allocate $byteCount bytes.');
}
return result;
}
/// Releases memory allocated on the native heap.
///
/// For POSIX-based systems, this uses `free`. On Windows, it uses `HeapFree`
/// against the default public heap. It may only be used against pointers
/// allocated in a manner equivalent to [allocate].
///
/// Throws an [ArgumentError] if the memory pointed to by [pointer] cannot be
/// freed.
///
// TODO(dartbug.com/36855): Once we have a ffi.Bool type we can use it instead
// of testing the return integer to be non-zero.
@override
void free(Pointer pointer) {
if (Platform.isWindows) {
if (winHeapFree(processHeap, /*flags=*/ 0, pointer) == 0) {
throw ArgumentError('Could not free $pointer.');
}
} else {
posixFree(pointer);
}
}
}
/// Manages memory on the native heap.
///
/// Initializes newly allocated memory to zero. Use [malloc] for unintialized
/// memory allocation.
///
/// For POSIX-based systems, this uses `calloc` and `free`. On Windows, it uses
/// `HeapAlloc` with [HEAP_ZERO_MEMORY] and `HeapFree` against the default
/// public heap.
const Allocator calloc = _CallocAllocator();