Revert "[vm/ffi] Roll package:ffi to Allocator and Opaque"

Revert submission 177862

Reason for revert: breaks g3 without https://github.com/flutter/engine/pull/23808
Reverted Changes:
I50b3b4c31:[vm/ffi] Roll `package:ffi` to `Allocator` and `Op...
I3f5b08c08:[vm/ffi] Change `Pointer<T extends Struct>.ref` to...
I6141c193b:[vm/ffi] Disallow empty structs

Change-Id: I128e7b096faea650e0ba0850a411eed3e97c00e6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/180185
Reviewed-by: Daco Harkes <dacoharkes@google.com>

DEPS

@@ -102,7 +102,7 @@ vars = {
 
   "chromedriver_tag": "83.0.4103.39",
   "dartdoc_rev" : "9e61a4f11091aaa8998525a2692b14148dc24ab5",
-  "ffi_rev": "ad6700de10ca3af16f0c3d9ff8aa15d2bd7cd21c",
+  "ffi_rev": "31352979f261f7c6ea88fa0a2cfb0fdd004c38fb",
   "fixnum_rev": "16d3890c6dc82ca629659da1934e412292508bba",
   "file_rev": "0e09370f581ab6388d46fda4cdab66638c0171a1",
   "glob_rev": "7c0ef8d4fa086f6b185c4dd724b700e7d7ad8f79",
@@ -115,7 +115,7 @@ vars = {
   "http_throttle_tag" : "1.0.2",
   "icu_rev" : "79326efe26e5440f530963704c3c0ff965b3a4ac",
   "idl_parser_rev": "5fb1ebf49d235b5a70c9f49047e83b0654031eb7",
-  "intl_tag": "ade5a936a1de62e7cd04c3ea956c02bd491d7868",
+  "intl_tag": "0.17.0-nullsafety",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",
   "json_rpc_2_rev": "b8dfe403fd8528fd14399dee3a6527b55802dd4d",
   "linter_tag": "0.1.128",

benchmarks/FfiBoringssl/dart/FfiBoringssl.dart

@@ -11,6 +11,7 @@ import 'dart:typed_data';
 import 'package:benchmark_harness/benchmark_harness.dart';
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'digest.dart';
 import 'types.dart';
 

benchmarks/FfiBoringssl/dart/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

benchmarks/FfiBoringssl/dart2/FfiBoringssl.dart

@@ -13,6 +13,7 @@ import 'dart:typed_data';
 import 'package:benchmark_harness/benchmark_harness.dart';
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'digest.dart';
 import 'types.dart';
 

benchmarks/FfiBoringssl/dart2/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

benchmarks/FfiCall/dart/FfiCall.dart

@@ -13,6 +13,7 @@ import 'dart:io';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
 import 'dlopen_helper.dart';
 
 //

benchmarks/FfiCall/dart/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

benchmarks/FfiCall/dart2/FfiCall.dart

@@ -15,6 +15,7 @@ import 'dart:io';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
 import 'dlopen_helper.dart';
 
 //

benchmarks/FfiCall/dart2/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

benchmarks/FfiMemory/dart/FfiMemory.dart

@@ -14,6 +14,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
+
 //
 // Pointer store.
 //

benchmarks/FfiMemory/dart/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

benchmarks/FfiMemory/dart2/FfiMemory.dart

@@ -16,6 +16,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
+
 //
 // Pointer store.
 //

benchmarks/FfiMemory/dart2/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

benchmarks/FfiStruct/dart/FfiStruct.dart

@@ -12,6 +12,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
+
 //
 // Struct field store (plus Pointer elementAt and load).
 //

benchmarks/FfiStruct/dart/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

benchmarks/FfiStruct/dart2/FfiStruct.dart

@@ -14,6 +14,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:benchmark_harness/benchmark_harness.dart';
 
+import 'calloc.dart';
+
 //
 // Struct field store (plus Pointer elementAt and load).
 //

benchmarks/FfiStruct/dart2/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

runtime/tests/vm/dart/isolates/dart_api_create_lightweight_isolate_test.dart

@@ -14,6 +14,7 @@ import 'dart:isolate';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../../tests/ffi/calloc.dart';
 import '../../../../../tests/ffi/dylib_utils.dart';
 
 final bool isAOT = Platform.executable.contains('dart_precompiled_runtime');

runtime/tests/vm/dart/regress_41971_test.dart

@@ -11,6 +11,8 @@ import 'dart:ffi';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../tests/ffi/calloc.dart';
+
 class X {
   int field;
   X(this.field);

runtime/tests/vm/dart/thread_priority_macos_test.dart

@@ -10,6 +10,8 @@ import 'dart:io';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../tests/ffi/calloc.dart';
+
 // pthread_t pthread_self()
 typedef PthreadSelfFT = int Function();
 typedef PthreadSelfNFT = IntPtr Function();

runtime/tests/vm/dart_2/isolates/dart_api_create_lightweight_isolate_test.dart

@@ -14,6 +14,7 @@ import 'dart:isolate';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../../tests/ffi/calloc.dart';
 import '../../../../../tests/ffi/dylib_utils.dart';
 
 final bool isAOT = Platform.executable.contains('dart_precompiled_runtime');

runtime/tests/vm/dart_2/regress_41971_test.dart

@@ -11,6 +11,8 @@ import 'dart:ffi';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../tests/ffi/calloc.dart';
+
 class X {
   int field;
   X(this.field);

runtime/tests/vm/dart_2/thread_priority_macos_test.dart

@@ -10,6 +10,8 @@ import 'dart:io';
 import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
+import '../../../../tests/ffi/calloc.dart';
+
 // pthread_t pthread_self()
 typedef PthreadSelfFT = int Function();
 typedef PthreadSelfNFT = IntPtr Function();

samples/ffi/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

samples/ffi/resource_management/pool.dart

@@ -9,6 +9,8 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import '../calloc.dart';
+
 /// An [Allocator] which frees all allocations at the same time.
 ///
 /// The pool allows you to allocate heap memory, but ignores calls to [free].

samples/ffi/resource_management/unmanaged_sample.dart

@@ -10,6 +10,7 @@ import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
 import 'utf8_helpers.dart';
+import '../calloc.dart';
 import '../dylib_utils.dart';
 
 main() {

samples/ffi/sample_ffi_bitfield.dart

@@ -7,6 +7,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:expect/expect.dart';
 
+import 'calloc.dart';
+
 /// typedef struct {
 ///     unsigned int bold      : 1;
 ///     unsigned int underline : 2;

samples/ffi/sample_ffi_data.dart

@@ -5,6 +5,8 @@
 import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
+
 main() {
   print('start main');
 

samples/ffi/sample_ffi_functions.dart

@@ -6,6 +6,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 typedef NativeUnaryOp = Int32 Function(Int32);

samples/ffi/sample_ffi_functions_callbacks.dart

@@ -6,6 +6,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'dylib_utils.dart';
 

samples/ffi/sample_ffi_functions_structs.dart

@@ -6,6 +6,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'dylib_utils.dart';
 

samples/ffi/sample_ffi_structs.dart

@@ -6,6 +6,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 
 main() {

samples/ffi/sqlite/lib/sqlite.dart

@@ -8,3 +8,5 @@
 library sqlite;
 
 export "src/database.dart";
+
+export "src/ffi/calloc.dart" show calloc;

samples/ffi/sqlite/lib/src/database.dart

@@ -15,6 +15,8 @@ import "bindings/types.dart" hide Database;
 import "bindings/constants.dart";
 import "collections/closable_iterator.dart";
 
+import 'ffi/calloc.dart';
+
 /// [Database] represents an open connection to a SQLite database.
 ///
 /// All functions against a database may throw [SQLiteError].

samples/ffi/sqlite/lib/src/ffi/arena.dart

@@ -7,6 +7,8 @@ import "dart:ffi";
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
+
 /// [Arena] manages allocated C memory.
 ///
 /// Arenas are zoned.

samples/ffi/sqlite/lib/src/ffi/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

samples_2/ffi/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

samples_2/ffi/resource_management/pool.dart

@@ -11,6 +11,8 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import '../calloc.dart';
+
 /// An [Allocator] which frees all allocations at the same time.
 ///
 /// The pool allows you to allocate heap memory, but ignores calls to [free].

samples_2/ffi/resource_management/unmanaged_sample.dart

@@ -12,6 +12,7 @@ import 'package:expect/expect.dart';
 import 'package:ffi/ffi.dart';
 
 import 'utf8_helpers.dart';
+import '../calloc.dart';
 import '../dylib_utils.dart';
 
 main() {

samples_2/ffi/sample_ffi_bitfield.dart

@@ -9,6 +9,8 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:expect/expect.dart';
 
+import 'calloc.dart';
+
 /// typedef struct {
 ///     unsigned int bold      : 1;
 ///     unsigned int underline : 2;

samples_2/ffi/sample_ffi_data.dart

@@ -7,6 +7,8 @@
 import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
+
 main() {
   print('start main');
 

samples_2/ffi/sample_ffi_functions.dart

@@ -8,6 +8,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 typedef NativeUnaryOp = Int32 Function(Int32);

samples_2/ffi/sample_ffi_functions_callbacks.dart

@@ -8,6 +8,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'dylib_utils.dart';
 

samples_2/ffi/sample_ffi_functions_structs.dart

@@ -8,6 +8,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'dylib_utils.dart';
 

samples_2/ffi/sample_ffi_structs.dart

@@ -8,6 +8,7 @@ import 'dart:ffi';
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 
 main() {

samples_2/ffi/sqlite/lib/sqlite.dart

@@ -10,3 +10,5 @@
 library sqlite;
 
 export "src/database.dart";
+
+export "src/ffi/calloc.dart" show calloc;

samples_2/ffi/sqlite/lib/src/database.dart

@@ -17,6 +17,8 @@ import "bindings/types.dart" hide Database;
 import "bindings/constants.dart";
 import "collections/closable_iterator.dart";
 
+import 'ffi/calloc.dart';
+
 /// [Database] represents an open connection to a SQLite database.
 ///
 /// All functions against a database may throw [SQLiteError].

samples_2/ffi/sqlite/lib/src/ffi/arena.dart

@@ -9,6 +9,8 @@ import "dart:ffi";
 
 import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
+
 /// [Arena] manages allocated C memory.
 ///
 /// Arenas are zoned.

samples_2/ffi/sqlite/lib/src/ffi/calloc.dart

@@ -0,0 +1,111 @@
+// 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.
+
+// @dart=2.9
+
+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();

tests/ffi/aliasing_test.dart

@@ -13,6 +13,7 @@ import 'dart:ffi';
 import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
+import 'calloc.dart';
 import 'ffi_test_helpers.dart';
 
 void main() {

tests/ffi/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

tests/ffi/calloc_test.dart

@@ -5,8 +5,8 @@
 import 'dart:ffi';
 
 import 'package:expect/expect.dart';
-import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 
 void main() {

tests/ffi/data_not_asan_test.dart

@@ -12,6 +12,8 @@ import 'dart:ffi';
 import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
+import 'calloc.dart';
+
 void main() {
   testPointerAllocateTooLarge();
   testPointerAllocateNegative();

tests/ffi/data_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'ffi_test_helpers.dart';
 
 void main() {

tests/ffi/extension_methods_test.dart

@@ -7,6 +7,8 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main(List<String> arguments) {
   for (int i = 0; i < 100; i++) {
     testStoreLoad();

tests/ffi/external_typed_data_test.dart

@@ -9,6 +9,8 @@ import 'dart:typed_data';
 import 'package:expect/expect.dart';
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main() {
   testInt8Load();
   testInt8Store();

tests/ffi/function_callbacks_structs_by_value_generated_test.dart

@@ -16,6 +16,7 @@ import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
 import 'callback_tests_utils.dart';
+import 'calloc.dart';
 
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';

tests/ffi/function_callbacks_structs_by_value_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';
 

tests/ffi/function_structs_by_value_generated_test.dart

@@ -15,6 +15,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");

tests/ffi/function_structs_test.dart

@@ -14,6 +14,7 @@ import 'dylib_utils.dart';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'very_large_struct.dart';
 

tests/ffi/function_test.dart

@@ -18,6 +18,7 @@ import 'dart:ffi';
 import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 void main() {

tests/ffi/generator/structs_by_value_tests_generator.dart

@@ -749,6 +749,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
@@ -801,6 +802,7 @@ import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
 import 'callback_tests_utils.dart';
+import 'calloc.dart';
 
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';

tests/ffi/regress_37254_test.dart

@@ -65,6 +65,8 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 // ===== a.value = b ======
 // The tests follow table cells left to right, top to bottom.
 void store1() {

tests/ffi/regress_39885_test.dart

@@ -6,6 +6,8 @@ import 'dart:ffi';
 
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main() {
   final data = calloc<Uint8>(3);
   for (int i = 0; i < 3; ++i) {

tests/ffi/regress_43693_test.dart

@@ -9,6 +9,7 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:expect/expect.dart';
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 class Struct43693 extends Struct {

tests/ffi/structs_nested_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");

tests/ffi/structs_nnbd_workaround_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'coordinate_nnbd_workaround.dart';
 
 void main() {

tests/ffi/structs_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'coordinate_bare.dart' as bare;
 import 'coordinate.dart';
 import 'ffi_test_helpers.dart';

tests/ffi/variance_function_test.dart

@@ -15,6 +15,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 typedef Int64PointerParamOpDart = void Function(Pointer<Int64>);

tests/ffi/vmspecific_enable_ffi_test.dart

@@ -10,6 +10,8 @@ import 'dart:ffi'; //# 01: compile-time error
 
 import 'package:ffi/ffi.dart'; //# 01: compile-time error
 
+import 'calloc.dart'; //# 01: compile-time error
+
 void main() {
   Pointer<Int8> p = //# 01: compile-time error
       calloc(); //# 01: compile-time error

tests/ffi/vmspecific_static_checks_test.dart

@@ -10,6 +10,7 @@ import 'dart:ffi';
 
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 void main() {

tests/ffi_2/aliasing_test.dart

@@ -13,6 +13,7 @@ import 'dart:ffi';
 import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
+import 'calloc.dart';
 import 'ffi_test_helpers.dart';
 
 void main() {

tests/ffi_2/calloc.dart

@@ -0,0 +1,109 @@
+// 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();

tests/ffi_2/calloc_test.dart

@@ -5,8 +5,8 @@
 import 'dart:ffi';
 
 import 'package:expect/expect.dart';
-import 'package:ffi/ffi.dart';
 
+import 'calloc.dart';
 import 'coordinate.dart';
 
 void main() {

tests/ffi_2/data_not_asan_test.dart

@@ -12,6 +12,8 @@ import 'dart:ffi';
 import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
+import 'calloc.dart';
+
 void main() {
   testPointerAllocateTooLarge();
   testPointerAllocateNegative();

tests/ffi_2/data_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'ffi_test_helpers.dart';
 
 void main() {

tests/ffi_2/extension_methods_test.dart

@@ -7,6 +7,8 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main(List<String> arguments) {
   for (int i = 0; i < 100; i++) {
     testStoreLoad();

tests/ffi_2/external_typed_data_test.dart

@@ -9,6 +9,8 @@ import 'dart:typed_data';
 import 'package:expect/expect.dart';
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main() {
   testInt8Load();
   testInt8Store();

tests/ffi_2/function_callbacks_structs_by_value_generated_test.dart

@@ -16,6 +16,7 @@ import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
 import 'callback_tests_utils.dart';
+import 'calloc.dart';
 
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';

tests/ffi_2/function_callbacks_structs_by_value_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';
 

tests/ffi_2/function_structs_by_value_generated_test.dart

@@ -15,6 +15,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");

tests/ffi_2/function_structs_test.dart

@@ -12,6 +12,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'coordinate.dart';
 import 'dylib_utils.dart';
 import 'very_large_struct.dart';

tests/ffi_2/function_test.dart

@@ -19,6 +19,7 @@ import "package:ffi/ffi.dart";
 import "package:expect/expect.dart";
 
 import 'dylib_utils.dart';
+import 'calloc.dart';
 
 void main() {
   for (int i = 0; i < 100; ++i) {

tests/ffi_2/generator/structs_by_value_tests_generator.dart

@@ -749,6 +749,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
@@ -801,6 +802,7 @@ import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
 import 'callback_tests_utils.dart';
+import 'calloc.dart';
 
 // Reuse the struct classes.
 import 'function_structs_by_value_generated_test.dart';

tests/ffi_2/null_test.dart

@@ -20,6 +20,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 import 'ffi_test_helpers.dart';
 

tests/ffi_2/regress_37254_test.dart

@@ -65,6 +65,8 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 // ===== a.value = b ======
 // The tests follow table cells left to right, top to bottom.
 void store1() {

tests/ffi_2/regress_39885_test.dart

@@ -6,6 +6,8 @@ import 'dart:ffi';
 
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
+
 main() {
   final data = calloc<Uint8>(3);
   for (int i = 0; i < 3; ++i) {

tests/ffi_2/regress_43693_test.dart

@@ -9,6 +9,7 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'package:expect/expect.dart';
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 class Struct43693 extends Struct {

tests/ffi_2/structs_nested_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");

tests/ffi_2/structs_test.dart

@@ -11,6 +11,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'coordinate_bare.dart' as bare;
 import 'coordinate.dart';
 import 'ffi_test_helpers.dart';

tests/ffi_2/variance_function_test.dart

@@ -15,6 +15,7 @@ import 'dart:ffi';
 import "package:expect/expect.dart";
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 typedef Int64PointerParamOpDart = void Function(Pointer<Int64>);

tests/ffi_2/vmspecific_enable_ffi_test.dart

@@ -10,6 +10,8 @@ import 'dart:ffi'; //# 01: compile-time error
 
 import 'package:ffi/ffi.dart'; //# 01: compile-time error
 
+import 'calloc.dart'; //# 01: compile-time error
+
 void main() {
   Pointer<Int8> p = //# 01: compile-time error
       calloc(); //# 01: compile-time error

tests/ffi_2/vmspecific_static_checks_test.dart

@@ -10,6 +10,7 @@ import 'dart:ffi';
 
 import "package:ffi/ffi.dart";
 
+import 'calloc.dart';
 import 'dylib_utils.dart';
 
 void main() {