From d72cedd70bff63c6ced2f2ea2588f999fb5c1c94 Mon Sep 17 00:00:00 2001
From: Steve Lee <slee@microsoft.com>
Date: Mon, 25 Jul 2022 15:07:26 -0700
Subject: [PATCH] Fix `FileSystemProvider` to work with volume and pipe paths
 (#15873)

---
 .../engine/Utils.cs                             |  6 +++---
 .../namespaces/FileSystemProvider.cs            | 17 +++++++++--------
 .../Get-ChildItem.Tests.ps1                     | 12 ++++++++++++
 3 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/src/System.Management.Automation/engine/Utils.cs b/src/System.Management.Automation/engine/Utils.cs
index 16ac72bfb1..eb6adb8b7a 100644
--- a/src/System.Management.Automation/engine/Utils.cs
+++ b/src/System.Management.Automation/engine/Utils.cs
@@ -1281,7 +1281,7 @@ namespace System.Management.Automation
             return false;
         }
 
-        internal static bool PathIsUnc(string path)
+        internal static bool PathIsUnc(string path, bool networkOnly = false)
         {
 #if UNIX
             return false;
@@ -1291,8 +1291,8 @@ namespace System.Management.Automation
                 return false;
             }
 
-            // handle special cases like \\wsl$\ubuntu which isn't a UNC path, but we can say it is so the filesystemprovider can use it
-            if (path.StartsWith(WslRootPath, StringComparison.OrdinalIgnoreCase))
+            // handle special cases like '\\wsl$\ubuntu', '\\?\', and '\\.\pipe\' which aren't a UNC path, but we can say it is so the filesystemprovider can use it
+            if (!networkOnly && (path.StartsWith(WslRootPath, StringComparison.OrdinalIgnoreCase) || path.StartsWith("\\\\?\\") || path.StartsWith("\\\\.\\")))
             {
                 return true;
             }
diff --git a/src/System.Management.Automation/namespaces/FileSystemProvider.cs b/src/System.Management.Automation/namespaces/FileSystemProvider.cs
index 84cc0d4782..3d28b5bb7c 100644
--- a/src/System.Management.Automation/namespaces/FileSystemProvider.cs
+++ b/src/System.Management.Automation/namespaces/FileSystemProvider.cs
@@ -132,20 +132,21 @@ namespace Microsoft.PowerShell.Commands
                     itemsToSkip = 4;
                 }
 
-                foreach (string item in path.Split(StringLiterals.DefaultPathSeparator))
+                var items = path.Split(StringLiterals.DefaultPathSeparator);
+                for (int i = 0; i < items.Length; i++)
                 {
                     if (itemsToSkip-- > 0)
                     {
                         // This handles the UNC server and share and 8.3 short path syntax
-                        exactPath += item + StringLiterals.DefaultPathSeparator;
+                        exactPath += items[i] + StringLiterals.DefaultPathSeparator;
                         continue;
                     }
                     else if (string.IsNullOrEmpty(exactPath))
                     {
                         // This handles the drive letter or / root path start
-                        exactPath = item + StringLiterals.DefaultPathSeparator;
+                        exactPath = items[i] + StringLiterals.DefaultPathSeparator;
                     }
-                    else if (string.IsNullOrEmpty(item))
+                    else if (string.IsNullOrEmpty(items[i]) && i == items.Length - 1)
                     {
                         // This handles the trailing slash case
                         if (!exactPath.EndsWith(StringLiterals.DefaultPathSeparator))
@@ -155,17 +156,17 @@ namespace Microsoft.PowerShell.Commands
 
                         break;
                     }
-                    else if (item.Contains('~'))
+                    else if (items[i].Contains('~'))
                     {
                         // This handles short path names
-                        exactPath += StringLiterals.DefaultPathSeparator + item;
+                        exactPath += StringLiterals.DefaultPathSeparator + items[i];
                     }
                     else
                     {
                         // Use GetFileSystemEntries to get the correct casing of this element
                         try
                         {
-                            var entries = Directory.GetFileSystemEntries(exactPath, item);
+                            var entries = Directory.GetFileSystemEntries(exactPath, items[i]);
                             if (entries.Length > 0)
                             {
                                 exactPath = entries[0];
@@ -7257,7 +7258,7 @@ namespace Microsoft.PowerShell.Commands
                     return false;
                 }
 
-                if (Utils.PathIsUnc(path))
+                if (Utils.PathIsUnc(path, networkOnly : true))
                 {
                     return true;
                 }
diff --git a/test/powershell/Modules/Microsoft.PowerShell.Management/Get-ChildItem.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Management/Get-ChildItem.Tests.ps1
index a5d06df0b4..5ab0a043f0 100644
--- a/test/powershell/Modules/Microsoft.PowerShell.Management/Get-ChildItem.Tests.ps1
+++ b/test/powershell/Modules/Microsoft.PowerShell.Management/Get-ChildItem.Tests.ps1
@@ -228,6 +228,18 @@ Describe "Get-ChildItem" -Tags "CI" {
             $barFiles = Get-ChildItem -Path testdrive:/foo/bar -Recurse
             $barFiles.Count | Should -Be 2
         }
+
+        It 'Works with Windows volume paths' -Skip:(!$IsWindows) {
+            $volume = (Get-Volume -DriveLetter $env:SystemDrive[0]).Path
+            $items = Get-ChildItem -LiteralPath "${volume}Windows"
+            $items[0].Parent | Should -BeExactly "${volume}Windows"
+            $items | Should -HaveCount (Get-ChildItem $env:SystemRoot).Count
+        }
+
+        It 'Works with Windows pipes' -Skip:(!$IsWindows) {
+            $out = pwsh -noprofile -custompipename myTestPipe { Get-ChildItem \\.\pipe\myTestPipe }
+            $out.Name | Should -BeExactly 'myTestPipe'
+        }
     }
 
     Context 'Env: Provider' {