1 files changed, 92 insertions, 0 deletions
diff --git a/src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.Creation.cs b/src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.Creation.cs
new file mode 100644
index 00000000000..a31af0e82e4
--- /dev/null
+++ b/src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.Creation.cs
@@ -0,0 +1,92 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+
+namespace System.Buffers
+{
+    /// <summary>
+    /// Contains factory methods to create <see cref="BoundedMemory{T}"/> instances.
+    /// </summary>
+    public static partial class BoundedMemory
+    {
+        /// <summary>
+        /// Allocates a new <see cref="BoundedMemory{T}"/> region which is immediately preceded by
+        /// or immediately followed by a poison (MEM_NOACCESS) page. If <paramref name="placement"/>
+        /// is <see cref="PoisonPagePlacement.Before"/>, then attempting to read the memory
+        /// immediately before the returned <see cref="BoundedMemory{T}"/> will result in an AV.
+        /// If <paramref name="placement"/> is <see cref="PoisonPagePlacement.After"/>, then
+        /// attempting to read the memory immediately after the returned <see cref="BoundedMemory{T}"/>
+        /// will result in AV.
+        /// </summary>
+        /// <remarks>
+        /// The newly-allocated memory will be populated with random data.
+        /// </remarks>
+        public static BoundedMemory<T> Allocate<T>(int elementCount, PoisonPagePlacement placement = PoisonPagePlacement.After) where T : unmanaged
+        {
+            if (elementCount < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(elementCount));
+            }
+            if (placement != PoisonPagePlacement.Before && placement != PoisonPagePlacement.After)
+            {
+                throw new ArgumentOutOfRangeException(nameof(placement));
+            }
+
+            var retVal = AllocateWithoutDataPopulation<T>(elementCount, placement);
+            FillRandom(MemoryMarshal.AsBytes(retVal.Span));
+            return retVal;
+        }
+
+        /// <summary>
+        /// Similar to <see cref="Allocate(int, PoisonPagePlacement)"/>, but populates the allocated
+        /// native memory block from existing data rather than using random data.
+        /// </summary>
+        public static BoundedMemory<T> AllocateFromExistingData<T>(ReadOnlySpan<T> data, PoisonPagePlacement placement = PoisonPagePlacement.After) where T : unmanaged
+        {
+            if (placement != PoisonPagePlacement.Before && placement != PoisonPagePlacement.After)
+            {
+                throw new ArgumentOutOfRangeException(nameof(placement));
+            }
+
+            var retVal = AllocateWithoutDataPopulation<T>(data.Length, placement);
+            data.CopyTo(retVal.Span);
+            return retVal;
+        }
+
+        /// <summary>
+        /// Similar to <see cref="Allocate(int, PoisonPagePlacement)"/>, but populates the allocated
+        /// native memory block from existing data rather than using random data.
+        /// </summary>
+        public static BoundedMemory<T> AllocateFromExistingData<T>(T[] data, PoisonPagePlacement placement = PoisonPagePlacement.After) where T : unmanaged
+        {
+            return AllocateFromExistingData(new ReadOnlySpan<T>(data), placement);
+        }
+
+        private static void FillRandom(Span<byte> buffer)
+        {
+            // Loop over a Random instance manually since Random.NextBytes(Span<byte>) doesn't
+            // exist on all platforms we target.
+
+            Random random = new Random(); // doesn't need to be cryptographically strong
+
+            for (int i = 0; i < buffer.Length; i++)
+            {
+                buffer[i] = (byte)random.Next();
+            }
+        }
+
+        private static BoundedMemory<T> AllocateWithoutDataPopulation<T>(int elementCount, PoisonPagePlacement placement) where T : unmanaged
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return AllocateWithoutDataPopulationWindows<T>(elementCount, placement);
+            }
+            else
+            {
+                return AllocateWithoutDataPopulationUnix<T>(elementCount, placement);
+            }
+        }
+    }
+}