Wrapper for Path Combine/GetExtension

Avoid throwing when handling Git items, that  allows other characters than
Windows file systems.
Similar to the .NET Core 2.1 API

GitCommands/FileAssociatedIconProvider.cs

@@ -51,7 +51,7 @@ public FileAssociatedIconProvider()
         /// </remarks>
         public Icon Get(string workingDirectory, string relativeFilePath)
         {
-            var extension = Path.GetExtension(relativeFilePath);
+            var extension = PathUtil.GetExtension(relativeFilePath);
             if (string.IsNullOrWhiteSpace(extension))
             {
                 return null;
@@ -68,7 +68,7 @@ public Icon Get(string workingDirectory, string relativeFilePath)
                     // extensions from the registry and using p/invokes and WinAPI, which have
                     // significantly higher maintenance overhead.
 
-                    var fullPath = Path.Combine(workingDirectory, relativeFilePath);
+                    var fullPath = PathUtil.Combine(workingDirectory, relativeFilePath);
                     if (!_fileSystem.File.Exists(fullPath))
                     {
                         tempFile = CreateTempFile(Path.GetFileName(fullPath));
@@ -117,4 +117,4 @@ internal void ResetCache()
             LoadedFileIcons.Clear();
         }
     }
-}
+}

GitCommands/Git/GitItemStatusFileExtensionComparer.cs

@@ -28,8 +28,8 @@ public override int Compare(GitItemStatus x, GitItemStatus y)
 
             var lhsPath = GetPrimarySortingPath(x);
             var rhsPath = GetPrimarySortingPath(y);
-            var lhsExt = Path.GetExtension(lhsPath);
-            var rhsExt = Path.GetExtension(rhsPath);
+            var lhsExt = PathUtil.GetExtension(lhsPath);
+            var rhsExt = PathUtil.GetExtension(rhsPath);
 
             var comparisonResult = StringComparer.InvariantCulture.Compare(lhsExt, rhsExt);
             if (comparisonResult == 0)

GitCommands/GitRevisionInfoProvider.cs

@@ -59,9 +59,7 @@ IEnumerable<IGitItem> YieldSubItems()
                 {
                     if (subItem is GitItem gitItem)
                     {
-                        gitItem.FileName = Path.Combine(
-                            basePath,
-                            gitItem.FileName ?? string.Empty);
+                        gitItem.FileName = PathUtil.Combine(basePath, gitItem.FileName) ?? string.Empty;
                     }
 
                     yield return subItem;

GitCommands/PathUtil.cs

@@ -132,6 +132,54 @@ public static string NormalizePath([NotNull] this string path)
             }
         }
 
+        /// <summary>
+        /// Wrapper for Path.Combine
+        /// </summary>
+        /// <remark>
+        /// Similar to the .NET Core 2.1 variant, except that null is returned if Windows
+        /// invalid characters (that may be accepted in Git or other filesystems)
+        /// are in the paths instead of a possible path (the OS or file system will throw
+        /// if the paths are invalid).
+        /// </remark>
+        /// <param name="path1">initial part</param>
+        /// <param name="path2">second part</param>
+        /// <returns>path if it can be combined, null otherwise</returns>
+        [CanBeNull]
+        public static string Combine(string path1, string path2)
+        {
+            try
+            {
+                return Path.Combine(path1, path2);
+            }
+            catch (ArgumentException)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Wrapper for Path.GetExtension
+        /// </summary>
+        /// <remark>
+        /// <see cref="Combine"/> for motivation.
+        /// </remark>
+        /// <param name="path">path to check</param>
+        /// <returns>path if it can be combined, empty otherwise</returns>
+        [NotNull]
+        public static string GetExtension(string path)
+        {
+            try
+            {
+                return Path.GetExtension(path);
+            }
+            catch (ArgumentException)
+            {
+                // This could return part after a '.' using string commands,
+                // but wait for .NET Core with this edge case
+                return string.Empty;
+            }
+        }
+
         [NotNull]
         public static string Resolve([NotNull] string path, string relativePath = "")
         {
@@ -223,7 +271,7 @@ public static bool TryFindFullPath([NotNull] string fileName, out string fullPat
 
                 foreach (var path in EnvironmentPathsProvider.GetEnvironmentValidPaths())
                 {
-                    fullPath = Path.Combine(path, fileName);
+                    fullPath = Combine(path, fileName);
                     if (File.Exists(fullPath))
                     {
                         return true;
@@ -251,7 +299,7 @@ public static bool TryFindShellPath([NotNull] string shell, out string shellPath
                     return true;
                 }
 
-                shellPath = Path.Combine(AppSettings.GitBinDir, shell);
+                shellPath = Combine(AppSettings.GitBinDir, shell);
                 if (File.Exists(shellPath))
                 {
                     return true;
@@ -369,7 +417,7 @@ string FindFileInEnvVarFolder(string environmentVariable, string location, strin
                     return null;
                 }
 
-                var path = Path.Combine(envVarFolder, location);
+                var path = Combine(envVarFolder, location);
                 if (!Directory.Exists(path))
                 {
                     return null;
@@ -380,7 +428,7 @@ string FindFileInEnvVarFolder(string environmentVariable, string location, strin
 
             string FindFile(string location, string fileName1)
             {
-                string fullName = Path.Combine(location, fileName1);
+                string fullName = Combine(location, fileName1);
                 if (File.Exists(fullName))
                 {
                     return fullName;

GitUI/AutoCompletion/CommitAutoCompleteProvider.cs

@@ -41,7 +41,7 @@ public async Task<IEnumerable<AutoCompleteWord>> GetAutoCompleteWordsAsync(Cance
             {
                 cancellationToken.ThrowIfCancellationRequested();
 
-                var regex = GetRegexForExtension(Path.GetExtension(file.Name));
+                var regex = GetRegexForExtension(PathUtil.GetExtension(file.Name));
 
                 if (regex != null)
                 {
@@ -94,7 +94,7 @@ private static Regex GetRegexForExtension(string extension)
 
         private static IEnumerable<string> ReadOrInitializeAutoCompleteRegexes()
         {
-            var path = Path.Combine(AppSettings.ApplicationDataPath.Value, "AutoCompleteRegexes.txt");
+            var path = PathUtil.Combine(AppSettings.ApplicationDataPath.Value, "AutoCompleteRegexes.txt");
 
             if (File.Exists(path))
             {

GitUI/CommandsDialogs/FormBrowse.cs

@@ -2015,14 +2015,20 @@ public static void CopyFullPathToClipboard(FileStatusList diffFiles, GitModule m
             var fileNames = new StringBuilder();
             foreach (var item in diffFiles.SelectedItems)
             {
+                var path = PathUtil.Combine(module.WorkingDir, item.Item.Name);
+                if (string.IsNullOrWhiteSpace(path))
+                {
+                    continue;
+                }
+
                 // Only use append line when multiple items are selected.
                 // This to make it easier to use the text from clipboard when 1 file is selected.
                 if (fileNames.Length > 0)
                 {
                     fileNames.AppendLine();
                 }
 
-                fileNames.Append(Path.Combine(module.WorkingDir, item.Item.Name).ToNativePath());
+                fileNames.Append(path.ToNativePath());
             }
 
             ClipboardUtil.TrySetText(fileNames.ToString());
@@ -2423,7 +2429,12 @@ public static void OpenContainingFolder(FileStatusList diffFiles, GitModule modu
 
             foreach (var item in diffFiles.SelectedItems)
             {
-                string filePath = Path.Combine(module.WorkingDir, item.Item.Name.ToNativePath());
+                string filePath = PathUtil.Combine(module.WorkingDir, item.Item.Name.ToNativePath());
+                if (string.IsNullOrWhiteSpace(filePath))
+                {
+                    continue;
+                }
+
                 FormBrowseUtil.ShowFileOrParentFolderInFileExplorer(filePath);
             }
         }

GitUI/CommandsDialogs/FormResolveConflicts.cs

@@ -314,17 +314,17 @@ private bool TryMergeWithScript(string fileName, string baseFileName, string loc
 
             try
             {
-                string extension = Path.GetExtension(fileName).ToLower();
+                string extension = PathUtil.GetExtension(fileName).ToLower();
                 if (extension.Length <= 1)
                 {
                     return false;
                 }
 
-                string dir = Path.Combine(Path.GetDirectoryName(Application.ExecutablePath), "Diff-Scripts").EnsureTrailingPathSeparator();
+                string dir = PathUtil.Combine(Path.GetDirectoryName(Application.ExecutablePath), "Diff-Scripts").EnsureTrailingPathSeparator();
                 if (Directory.Exists(dir))
                 {
                     if (_mergeScripts.TryGetValue(extension, out var mergeScript) &&
-                        File.Exists(Path.Combine(dir, mergeScript)))
+                        File.Exists(PathUtil.Combine(dir, mergeScript)))
                     {
                         if (MessageBox.Show(this, string.Format(_uskUseCustomMergeScript.Text, mergeScript),
                                             _uskUseCustomMergeScriptCaption.Text, MessageBoxButtons.YesNo, MessageBoxIcon.Question) ==

GitUI/CommandsDialogs/RevisionFileTreeController.cs

@@ -120,16 +120,17 @@ public void LoadChildren(IGitItem item, TreeNodeCollection nodes, ImageList.Imag
 
                     case GitObjectType.Blob:
                         {
-                            var extension = Path.GetExtension(gitItem.FileName);
+                            var extension = PathUtil.GetExtension(gitItem.FileName);
+
                             if (string.IsNullOrWhiteSpace(extension))
                             {
                                 continue;
                             }
 
                             if (!imageCollection.ContainsKey(extension))
                             {
-                                // a little optimisation - initialise the first time it is required
-                                workingDir = workingDir ?? _getWorkingDir();
+                                // lazy - initialise the first time used
+                                workingDir ??= _getWorkingDir();
 
                                 var fileIcon = _iconProvider.Get(workingDir, gitItem.FileName);
                                 if (fileIcon == null)

GitUI/CommandsDialogs/SettingsDialog/Pages/ChecklistSettingsPage.cs

@@ -555,8 +555,8 @@ private bool CheckGitExtensionRegistrySettings()
                                                       null)))
             {
                 // Check if shell extensions are installed
-                string path32 = Path.Combine(AppSettings.GetInstallDir(), CommonLogic.GitExtensionsShellEx32Name);
-                string path64 = Path.Combine(AppSettings.GetInstallDir(), CommonLogic.GitExtensionsShellEx64Name);
+                string path32 = PathUtil.Combine(AppSettings.GetInstallDir(), CommonLogic.GitExtensionsShellEx32Name);
+                string path64 = PathUtil.Combine(AppSettings.GetInstallDir(), CommonLogic.GitExtensionsShellEx64Name);
                 if (!File.Exists(path32) || (IntPtr.Size == 8 && !File.Exists(path64)))
                 {
                     RenderSettingSet(ShellExtensionsRegistered, ShellExtensionsRegistered_Fix, _shellExtNoInstalled.Text);

GitUI/CommandsDialogs/SettingsDialog/Pages/FormChooseTranslation.cs

@@ -36,7 +36,7 @@ protected override void OnLoad(EventArgs e)
 
             foreach (string translation in translations)
             {
-                var imagePath = Path.Combine(Translator.GetTranslationDir(), translation + ".gif");
+                var imagePath = PathUtil.Combine(Translator.GetTranslationDir(), translation + ".gif");
                 if (File.Exists(imagePath))
                 {
                     var image = Image.FromFile(imagePath);

GitUI/CommandsDialogs/SettingsDialog/Pages/FormFixHome.cs

@@ -64,7 +64,7 @@ private static bool IsFixHome()
                     try
                     {
                         if (!string.IsNullOrEmpty(candidate) &&
-                            File.Exists(Path.Combine(candidate, ".gitconfig")))
+                            File.Exists(PathUtil.Combine(candidate, ".gitconfig")))
                         {
                             return true;
                         }
@@ -138,7 +138,7 @@ private void LoadSettings()
             try
             {
                 string userHomeDir = Environment.GetEnvironmentVariable("HOME", EnvironmentVariableTarget.User);
-                if (!string.IsNullOrEmpty(userHomeDir) && File.Exists(Path.Combine(userHomeDir, ".gitconfig")))
+                if (!string.IsNullOrEmpty(userHomeDir) && File.Exists(PathUtil.Combine(userHomeDir, ".gitconfig")))
                 {
                     MessageBox.Show(this, string.Format(_gitconfigFoundHome.Text, userHomeDir), "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                     defaultHome.Checked = true;
@@ -156,7 +156,7 @@ private void LoadSettings()
             {
                 var path = Environment.GetEnvironmentVariable("HOMEDRIVE") +
                            Environment.GetEnvironmentVariable("HOMEPATH");
-                if (!string.IsNullOrEmpty(path) && File.Exists(Path.Combine(path, ".gitconfig")))
+                if (!string.IsNullOrEmpty(path) && File.Exists(PathUtil.Combine(path, ".gitconfig")))
                 {
                     MessageBox.Show(this, string.Format(_gitconfigFoundHomedrive.Text, path), "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                     defaultHome.Checked = true;
@@ -173,7 +173,7 @@ private void LoadSettings()
             try
             {
                 var path = Environment.GetEnvironmentVariable("USERPROFILE");
-                if (!string.IsNullOrEmpty(path) && File.Exists(Path.Combine(path, ".gitconfig")))
+                if (!string.IsNullOrEmpty(path) && File.Exists(PathUtil.Combine(path, ".gitconfig")))
                 {
                     MessageBox.Show(this, string.Format(_gitconfigFoundUserprofile.Text, path), "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                     userprofileHome.Checked = true;
@@ -190,7 +190,7 @@ private void LoadSettings()
             try
             {
                 var path = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
-                if (!string.IsNullOrEmpty(path) && File.Exists(Path.Combine(path, ".gitconfig")))
+                if (!string.IsNullOrEmpty(path) && File.Exists(PathUtil.Combine(path, ".gitconfig")))
                 {
                     MessageBox.Show(this, string.Format(_gitconfigFoundPersonalFolder.Text, Environment.GetFolderPath(Environment.SpecialFolder.Personal)),
                         "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);

GitUI/Editor/FileViewer.cs

@@ -567,7 +567,7 @@ public Task ViewGitItemAsync(GitItemStatus file, [CanBeNull] Action openWithDiff
             {
                 // File system access for other than Worktree,
                 // to handle that git-status does not detect details for untracked (git-diff --no-index will not give info)
-                var fullPath = Path.Combine(Module.WorkingDir, file.Name);
+                var fullPath = PathUtil.Combine(Module.WorkingDir, file.Name);
                 if (Directory.Exists(fullPath) && GitModule.IsValidGitWorkingDir(fullPath))
                 {
                     isSubmodule = true;

Plugins/Statistics/GitStatistics/LineCounter.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using GitCommands;
 
 namespace GitStatistics
 {
@@ -53,7 +54,7 @@ IEnumerable<FileInfo> GetFiles()
             {
                 foreach (var file in filesToCheck)
                 {
-                    if (extensions.Contains(Path.GetExtension(file)))
+                    if (extensions.Contains(PathUtil.GetExtension(file)))
                     {
                         FileInfo fileInfo;
                         try
@@ -98,4 +99,4 @@ void AddFile(FileInfo file)
             }
         }
     }
-}
+}

UnitTests/GitCommands.Tests/Helpers/PathUtilTest.cs

@@ -188,6 +188,24 @@ public void NormalizePath(string path, string expected)
             PathUtil.NormalizePath(path).Should().Be(expected);
         }
 
+        [TestCase(@"C:\work\t.txt", "whatever", @"C:\work\t.txt\whatever")]
+        [TestCase(@"C:\wor""k\t.txt", "whatever", null)]
+        [TestCase(@"\\WSL$\Ubuntu\home\jack\.\work\", "whatever", @"\\WSL$\Ubuntu\home\jack\.\work\whatever")]
+        public void Combine(string path1, string path2, string expected)
+        {
+            PathUtil.Combine(path1, path2).Should().Be(expected);
+        }
+
+        [TestCase(@"C:\work\t.txt", @".txt")]
+        [TestCase(@"C:\work\t.", @"")]
+        [TestCase(@"work/t.bmp", @".bmp")]
+        [TestCase(@"work""/t.bmp", @"")]
+        [TestCase(@"\\WSL$\Ubuntu\home\jack\.\work", @"")]
+        public void GetExtension(string path, string expected)
+        {
+            PathUtil.GetExtension(path).Should().Be(expected);
+        }
+
         [TestCase(@"C:\WORK\GitExtensions\", @"C:\WORK\GitExtensions\")]
         [TestCase(@"\\my-pc\Work\GitExtensions\", @"\\my-pc\Work\GitExtensions\")]
         [TestCase(@"\\wsl$\Ubuntu\home\jack\work\", @"\\wsl$\Ubuntu\home\jack\work\")]