[release/5.0] P/Invoke function returning SafeSocketHandle throws MissingMethodException (#45911)

src/libraries/System.IO.MemoryMappedFiles/src/ILLinkTrim_LibraryBuild.xml

@@ -0,0 +1,8 @@
+<linker>
+  <assembly fullname="System.IO.MemoryMappedFiles">
+    <type fullname="Microsoft.Win32.SafeHandles.SafeMemoryMappedViewHandle">
+      <!-- don't trim the default constructor, since it is necessary for p/invokes made by external code -->
+      <method name=".ctor" />
+    </type>
+  </assembly>
+</linker>

src/libraries/System.IO.MemoryMappedFiles/tests/SafeMemoryMappedViewHandleTests.cs

@@ -0,0 +1,72 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+using Microsoft.Win32.SafeHandles;
+using Xunit;
+
+namespace System.IO.MemoryMappedFiles.Tests
+{
+    /// <summary>
+    /// Tests for SafeMemoryMappedViewHandle
+    /// </summary>
+    public class SafeMemoryMappedViewHandleTests : MemoryMappedFilesTestBase
+    {
+        /// <summary>
+        /// Tests that external code can use SafeMemoryMappedViewHandle as the result of a P/Invoke on Windows.
+        /// </summary>
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows)]
+        public void SafeMemoryMappedViewHandle_CanUseInPInvoke_Windows()
+        {
+            const int BUF_SIZE = 256;
+
+            Interop.Kernel32.SECURITY_ATTRIBUTES secAttrs = default;
+            using SafeMemoryMappedFileHandle fileHandle = Interop.Kernel32.CreateFileMapping(
+                new IntPtr(-1),
+                ref secAttrs,
+                Interop.Kernel32.PageOptions.PAGE_EXECUTE_READWRITE,
+                0,
+                BUF_SIZE,
+                CreateUniqueMapName());
+
+            using SafeMemoryMappedViewHandle handle = Interop.Kernel32.MapViewOfFile(
+                fileHandle,
+                Interop.Kernel32.FileMapOptions.FILE_MAP_READ,
+                0,
+                0,
+                (UIntPtr)BUF_SIZE);
+
+            Assert.NotNull(handle);
+        }
+
+        /// <summary>
+        /// Tests that external code can use SafeMemoryMappedViewHandle as the result of a P/Invoke on Unix.
+        /// </summary>
+        [Fact]
+        [PlatformSpecific(TestPlatforms.AnyUnix & ~TestPlatforms.Browser)]
+        public void SafeMemoryMappedViewHandle_CanUseInPInvoke_Unix()
+        {
+            const int MAP_PRIVATE = 0x02;
+            const int MAP_ANONYMOUS = 0x10;
+
+            const int PROT_READ = 0x1;
+            const int PROT_WRITE = 0x2;
+
+            // The handle returned may be invalid, but this is testing that the
+            // SafeHandle object can successfully be created in a P/Invoke
+            using SafeMemoryMappedViewHandle handle = mmap(
+                IntPtr.Zero,
+                1,
+                PROT_READ | PROT_WRITE,
+                MAP_PRIVATE | MAP_ANONYMOUS,
+                -1,
+                0);
+
+            Assert.NotNull(handle);
+        }
+
+        [DllImport("libc")]
+        private static unsafe extern SafeMemoryMappedViewHandle mmap(IntPtr addr, nint lengthint, int prot, int flags, int fd, nuint offset);
+    }
+}

src/libraries/System.IO.MemoryMappedFiles/tests/System.IO.MemoryMappedFiles.Tests.csproj

@@ -17,6 +17,13 @@
     <Compile Include="MemoryMappedFilesTestsBase.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
     <Compile Include="$(CommonTestPath)System\IO\TempFile.cs"
              Link="Common\System\IO\TempFile.cs" />
+    <Compile Include="SafeMemoryMappedViewHandleTests.cs" />
     <Compile Include="XunitAssemblyAttributes.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Interop.BOOL.cs" Link="ProductionCode\Common\Interop\Windows\Interop.BOOL.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Interop.Libraries.cs" Link="ProductionCode\Common\Interop\Windows\Interop.Libraries.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.CreateFileMapping.cs" Link="ProductionCode\Common\Interop\Windows\Kernel32\Interop.CreateFileMapping.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.MapViewOfFile.cs" Link="ProductionCode\Common\Interop\Windows\Kernel32\Interop.MapViewOfFile.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.MemOptions.cs" Link="ProductionCode\Common\Interop\Windows\Kernel32\Interop.MemOptions.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.SECURITY_ATTRIBUTES.cs" Link="ProductionCode\Common\Interop\Windows\Kernel32\Interop.SECURITY_ATTRIBUTES.cs" />
   </ItemGroup>
-</Project>
+</Project>

src/libraries/System.Net.Sockets/src/ILLinkTrim_LibraryBuild.xml

@@ -0,0 +1,8 @@
+<linker>
+  <assembly fullname="System.Net.Sockets">
+    <type fullname="System.Net.Sockets.SafeSocketHandle">
+      <!-- don't trim the default constructor, since it is necessary for p/invokes made by external code -->
+      <method name=".ctor" />
+    </type>
+  </assembly>
+</linker>

src/libraries/System.Net.Sockets/tests/FunctionalTests/SafeHandleTest.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Runtime.InteropServices;
 using Xunit;
 
 namespace System.Net.Sockets.Tests
@@ -15,5 +16,27 @@ public static void SafeHandle_NotIsInvalid()
                 Assert.False(s.SafeHandle.IsInvalid);
             }
         }
+
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows | TestPlatforms.AnyUnix)]
+        public void SafeSocketHandle_CanUseInPInvoke()
+        {
+            const int AF_INET = 2;
+            const int SOCK_STREAM = 1;
+
+            using SafeSocketHandle handle = Socket(AF_INET, SOCK_STREAM, 0);
+            Assert.NotNull(handle);
+        }
+
+        private static SafeSocketHandle Socket(int af, int type, int protocol) =>
+            OperatingSystem.IsWindows() ?
+                SocketWindows(af, type, protocol) :
+                SocketUnix(af, type, protocol);
+
+        [DllImport("ws2_32.dll", EntryPoint = "socket")]
+        private static extern SafeSocketHandle SocketWindows(int af, int type, int protocol);
+
+        [DllImport("libc", EntryPoint = "socket")]
+        private static extern SafeSocketHandle SocketUnix(int af, int type, int protocol);
     }
 }