PowerShell · daxian-dbw · Jul 6, 2020 · Jun 27, 2020 · Jun 27, 2020 · Jun 27, 2020
diff --git a/src/System.Management.Automation/engine/Utils.cs b/src/System.Management.Automation/engine/Utils.cs
@@ -2080,6 +2080,8 @@ public static class InternalTestHooks
 
         internal static bool ShowMarkdownOutputBypass;
 
+        internal static bool ThrowExdevErrorOnMoveDirectory;
+
         /// <summary>This member is used for internal test purposes.</summary>
         public static void SetTestHook(string property, object value)
         {

diff --git a/src/System.Management.Automation/namespaces/FileSystemProvider.cs b/src/System.Management.Automation/namespaces/FileSystemProvider.cs
@@ -51,6 +51,12 @@ public sealed partial class FileSystemProvider : NavigationCmdletProvider,
                                                      ISecurityDescriptorCmdletProvider,
                                                      ICmdletProviderSupportsHelp
     {
+#if UNIX
+        // This is the errno returned by the rename() syscall
+        // when an item is attempted to be renamed across filesystem mount boundaries.
+        private const int UNIX_ERRNO_EXDEV = 18;
+#endif
+
         // 4MB gives the best results without spiking the resources on the remote connection for file transfers between pssessions.
         // NOTE: The script used to copy file data from session (PSCopyFromSessionHelper) has a
         // maximum fragment size value for security.  If FILETRANSFERSIZE changes make sure the
@@ -6001,15 +6007,7 @@ private void MoveDirectoryInfoItem(
 
             try
             {
-                if (!IsSameVolume(directory.FullName, destination))
-                {
-                    CopyAndDelete(directory, destination, force);
-                }
-                else
-                {
-                    // Move the file
-                    directory.MoveTo(destination);
-                }
+                MoveDirectoryInfoUnchecked(directory, destination, force);
 
                 WriteItemObject(
                     directory,
@@ -6027,14 +6025,7 @@ private void MoveDirectoryInfoItem(
                         directory.Attributes =
                             directory.Attributes & ~(FileAttributes.ReadOnly | FileAttributes.Hidden);
 
-                        if (!IsSameVolume(directory.FullName, destination))
-                        {
-                            CopyAndDelete(directory, destination, force);
-                        }
-                        else
-                        {
-                            directory.MoveTo(destination);
-                        }
+                        MoveDirectoryInfoUnchecked(directory, destination, force);
 
                         WriteItemObject(directory, directory.FullName, true);
                     }
@@ -6072,6 +6063,47 @@ private void MoveDirectoryInfoItem(
             }
         }
 
+        /// <summary>
+        /// Implements the file move operation for directories without handling any error scenarios.
+        /// In particular, this attempts to rename or copy+delete the file,
+        /// but passes any exceptional behavior through to the caller.
+        /// </summary>
+        /// <param name="directory">The directory to move.</param>
+        /// <param name="destinationPath">The destination path to move the directory to.</param>
+        /// <param name="force">If true, force move the directory, overwriting anything at the destination.</param>
+        private void MoveDirectoryInfoUnchecked(DirectoryInfo directory, string destinationPath, bool force)
+        {
+#if UNIX
+            try
+            {
+                if (InternalTestHooks.ThrowExdevErrorOnMoveDirectory)
+                {
+                    throw new IOException("Invalid cross-device link", hresult: UNIX_ERRNO_EXDEV);
+                }
+
+                directory.MoveTo(destinationPath);
+            }
+            catch (IOException e) when (e.HResult == UNIX_ERRNO_EXDEV)
+            {
+                // Rather than try to ascertain whether we can rename a directory ahead of time,
+                // it's both faster and more correct to try to rename it and fall back to copy/deleting it
+                // See also: https://github.com/coreutils/coreutils/blob/439741053256618eb651e6d43919df29625b8714/src/mv.c#L212-L216
+                CopyAndDelete(directory, destinationPath, force);
+            }
+#else
+            // On Windows, being able to rename vs copy/delete a file
+            // is just a question of the drive
+            if (IsSameWindowsVolume(directory.FullName, destinationPath))
+            {
+                directory.MoveTo(destinationPath);
+            }
+            else
+            {
+                CopyAndDelete(directory, destinationPath, force);
+            }
+#endif
+        }
+
         private void CopyAndDelete(DirectoryInfo directory, string destination, bool force)
         {
             if (!ItemExists(destination))
@@ -6107,13 +6139,15 @@ private void CopyAndDelete(DirectoryInfo directory, string destination, bool for
             }
         }
 
-        private bool IsSameVolume(string source, string destination)
+#if !UNIX
+        private bool IsSameWindowsVolume(string source, string destination)
         {
             FileInfo src = new FileInfo(source);
             FileInfo dest = new FileInfo(destination);
 
             return (src.Directory.Root.Name == dest.Directory.Root.Name);
         }
+#endif
 
         #endregion MoveItem
 

diff --git a/test/powershell/Modules/Microsoft.PowerShell.Management/FileSystem.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Management/FileSystem.Tests.ps1
@@ -131,12 +131,36 @@ Describe "Basic FileSystem Provider Tests" -Tags "CI" {
             "$destDir/$testDir/$testFile" | Should -Exist
         }
 
+        It "Verify Move-Item across devices for directory" {
+            [System.Management.Automation.Internal.InternalTestHooks]::SetTestHook('ThrowExdevErrorOnMoveDirectory', $true)
+            try
+            {
+                $dir = (New-Item -Path TestDrive:/dir -ItemType Directory -ErrorAction Stop).FullName
+                $file = (New-Item -Path "$dir/file.txt" -Value "HELLO" -ErrorAction Stop).Name
+                $destination = "$TestDrive/destination"
+
+                Move-Item -Path $dir -Destination $destination -ErrorAction Stop
+
+                $dir | Should -Not -Exist
+                $destination | Should -Exist
+                "$destination/$file" | Should -Exist
+            }
+            finally
+            {
+                [System.Management.Automation.Internal.InternalTestHooks]::SetTestHook('ThrowExdevErrorOnMoveDirectory', $false)
+            }
+        }
+
         It "Verify Move-Item will not move to an existing file" {
             { Move-Item -Path $testDir -Destination $testFile -ErrorAction Stop } | Should -Throw -ErrorId "MoveDirectoryItemIOError,Microsoft.PowerShell.Commands.MoveItemCommand"
             $error[0].Exception | Should -BeOfType System.IO.IOException
             $testDir | Should -Exist
         }
 
+        It "Verify Move-Item throws correct error for non-existent source" {
+            { Move-Item -Path /does/not/exist -Destination $testFile -ErrorAction Stop } | Should -Throw -ErrorId 'PathNotFound,Microsoft.PowerShell.Commands.MoveItemCommand'
+        }
+
         It "Verify Move-Item as substitute for Rename-Item" {
             $newFile = Move-Item -Path $testFile -Destination $newTestFile -PassThru
             $fileExists = Test-Path $newTestFile