Merge a23d09c6dd into 02596ba8d9

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.FileAttributes.cs

@@ -7,6 +7,8 @@ internal static partial class Interop
     {
         internal static partial class FileAttributes
         {
+            internal const int INVALID_FILE_ATTRIBUTES = -1;
+
             internal const int FILE_ATTRIBUTE_NORMAL = 0x00000080;
             internal const int FILE_ATTRIBUTE_READONLY = 0x00000001;
             internal const int FILE_ATTRIBUTE_DIRECTORY = 0x00000010;

src/libraries/Common/src/System/IO/FileSystem.Attributes.Windows.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -25,7 +26,7 @@ namespace System.IO
 
             return
                 (lastError == 0) &&
-                (data.dwFileAttributes != -1) &&
+                (data.dwFileAttributes != Interop.Kernel32.FileAttributes.INVALID_FILE_ATTRIBUTES) &&
                 ((data.dwFileAttributes & Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY) != 0);
         }
 
@@ -36,7 +37,7 @@ namespace System.IO
 
             return
                 (errorCode == 0) &&
-                (data.dwFileAttributes != -1) &&
+                (data.dwFileAttributes != Interop.Kernel32.FileAttributes.INVALID_FILE_ATTRIBUTES) &&
                 ((data.dwFileAttributes & Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY) == 0);
         }
 
@@ -56,7 +57,14 @@ namespace System.IO
 
             using (DisableMediaInsertionPrompt.Create())
             {
-                if (!Interop.Kernel32.GetFileAttributesEx(path, Interop.Kernel32.GET_FILEEX_INFO_LEVELS.GetFileExInfoStandard, ref data))
+                // Using 'GetFileAttributesEx' to get file attributes of a pipe
+                // will inevitably open that pipe making it useless for a consumer,
+                // thus we need to handle this case separately
+                if (IsPipePath(path))
+                {
+                    errorCode = GetFileAttributeInfoUsingFindFileApi(path, ref data);
+                }
+                else if (!Interop.Kernel32.GetFileAttributesEx(path, Interop.Kernel32.GET_FILEEX_INFO_LEVELS.GetFileExInfoStandard, ref data))
                 {
                     errorCode = Marshal.GetLastPInvokeError();
 
@@ -79,19 +87,7 @@ namespace System.IO
                         // pagefile.sys case. As such we're probably stuck filtering out specific
                         // cases that we know we don't want to retry on.
 
-                        Interop.Kernel32.WIN32_FIND_DATA findData = default;
-                        using (SafeFindHandle handle = Interop.Kernel32.FindFirstFile(path!, ref findData))
-                        {
-                            if (handle.IsInvalid)
-                            {
-                                errorCode = Marshal.GetLastPInvokeError();
-                            }
-                            else
-                            {
-                                errorCode = Interop.Errors.ERROR_SUCCESS;
-                                data.PopulateFrom(ref findData);
-                            }
-                        }
+                        errorCode = GetFileAttributeInfoUsingFindFileApi(path!, ref data);
                     }
                 }
             }
@@ -104,12 +100,65 @@ namespace System.IO
                     case Interop.Errors.ERROR_PATH_NOT_FOUND:
                     case Interop.Errors.ERROR_NOT_READY: // Removable media not ready
                         // Return default value for backward compatibility
-                        data.dwFileAttributes = -1;
+                        data.dwFileAttributes = Interop.Kernel32.FileAttributes.INVALID_FILE_ATTRIBUTES;
                         return Interop.Errors.ERROR_SUCCESS;
                 }
             }
 
             return errorCode;
+
+            static int GetFileAttributeInfoUsingFindFileApi(string path, ref Interop.Kernel32.WIN32_FILE_ATTRIBUTE_DATA data)
+            {
+                Interop.Kernel32.WIN32_FIND_DATA findData = default;
+                using (SafeFindHandle handle = Interop.Kernel32.FindFirstFile(path, ref findData))
+                {
+                    if (handle.IsInvalid)
+                    {
+                        return Marshal.GetLastPInvokeError();
+                    }
+                    else
+                    {
+                        data.PopulateFrom(ref findData);
+                        return Interop.Errors.ERROR_SUCCESS;
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Tells whether a given path is a Windows pipe path.
+        /// Examples of pipe paths are:
+        /// <list type="bullet">
+        /// <item>
+        /// <c>\\.\pipe\pipeName</c> - local pipe path
+        /// </item>
+        /// <item>
+        /// <c>\\serverName\pipe\pipeName</c> - remote pipe path
+        /// </item>
+        /// </list>
+        /// </summary>
+        private static bool IsPipePath([NotNullWhen(true)] string? path)
+        {
+            if (path is null)
+            {
+                return false;
+            }
+
+            ReadOnlySpan<char> pathSpan = path.AsSpan();
+            if (!pathSpan.StartsWith(@"\\"))
+            {
+                return false;
+            }
+
+            pathSpan = pathSpan.Slice(2);
+            Span<Range> segments = stackalloc Range[3];
+            int written = pathSpan.Split(segments, '\\');
+
+            // 3 segments of a pipe path:
+            // 1) '.' or 'serverName'
+            // 2) Constant 'pipe' segment
+            // 3) Pipe name
+            return written == 3 && pathSpan[segments[1]].SequenceEqual("pipe");
         }
 
         internal static bool IsPathUnreachableError(int errorCode) =>

src/libraries/System.Private.CoreLib/src/System/IO/FileSystemInfo.Windows.cs

@@ -75,7 +75,8 @@ namespace System.IO
                     // but Exists is supposed to return true or false.
                     return false;
                 }
-                return (_data.dwFileAttributes != -1) && ((this is DirectoryInfo) == ((_data.dwFileAttributes & Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY) == Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY));
+                return (_data.dwFileAttributes != Interop.Kernel32.FileAttributes.INVALID_FILE_ATTRIBUTES) &&
+                       ((this is DirectoryInfo) == ((_data.dwFileAttributes & Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY) == Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY));
             }
         }
 

src/libraries/System.Private.CoreLib/src/System/IO/Path.Windows.cs

@@ -34,7 +34,7 @@ namespace System.IO
         {
             Interop.Kernel32.WIN32_FILE_ATTRIBUTE_DATA data = default;
             int errorCode = FileSystem.FillAttributeInfo(fullPath, ref data, returnErrorOnNotFound: true);
-            bool result = (errorCode == Interop.Errors.ERROR_SUCCESS) && (data.dwFileAttributes != -1);
+            bool result = (errorCode == Interop.Errors.ERROR_SUCCESS) && (data.dwFileAttributes != Interop.Kernel32.FileAttributes.INVALID_FILE_ATTRIBUTES);
             isDirectory = result && (data.dwFileAttributes & Interop.Kernel32.FileAttributes.FILE_ATTRIBUTE_DIRECTORY) != 0;
 
             return result;

src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/Exists.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.IO.Pipes;
+using System.Threading;
 using Xunit;
 
 namespace System.IO.Tests
@@ -230,6 +232,44 @@ namespace System.IO.Tests
             Assert.False(Exists(component));
         }
 
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows)] // Windows-specific pipes behavior
+        public void CheckPipeExistsViaFileApi()
+        {
+            var pipeName = GetNamedPipeServerStreamName();
+            using var server = new NamedPipeServerStream(pipeName);
+            Assert.True(Exists(@$"\\.\pipe\{pipeName}"));
+        }
+
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows)] // Windows-specific pipes behavior
+        public void CheckPipeDoesNotExistViaFileApi()
+        {
+            var pipeName = GetNamedPipeServerStreamName();
+            new NamedPipeServerStream(pipeName).Dispose();
+            Assert.False(Exists(@$"\\.\pipe\{pipeName}"));
+        }
+
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows)] // Windows-specific pipes behavior
+        public void CheckingPipeExistenceViaFileApiDoesNotInvalidateIt()
+        {
+            var pipeName = GetNamedPipeServerStreamName();
+
+            using var server = new NamedPipeServerStream(pipeName);
+            var connectedEvent = new ManualResetEventSlim(initialState: false);
+            var connectResult = server.BeginWaitForConnection(_ => { connectedEvent.Set(); }, state: null);
+
+            Assert.True(Exists(@$"\\.\pipe\{pipeName}"));
+
+            using var client = new NamedPipeClientStream(pipeName);
+            client.Connect(timeout: 1000);
+
+            server.EndWaitForConnection(connectResult);
+
+            Assert.True(connectedEvent.Wait(millisecondsTimeout: 1000));
+        }
+
         #endregion
     }