New symbolic link implementation for legacy windows

test/Velopack.Tests/SymbolicLinkTests.cs

@@ -1,8 +1,8 @@
-using System.ComponentModel;
-using System.IO.Compression;
-using NCode.ReparsePoints;
+using System.IO.Compression;
+using System.Runtime.InteropServices;
 using Velopack.Logging;
 using Velopack.Util;
+using NCode.ReparsePoints;
 
 namespace Velopack.Tests;
 
@@ -270,4 +270,356 @@ public class SymbolicLinkTests
         Assert.True(File.Exists(currentSym));
         Assert.Equal("A/", File.ReadAllText(currentSym));
     }
+
+    // ===== New comprehensive tests =====
+
+    [Fact]
+    public void Create_SymlinkToNonExistentTarget_ShouldWork()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "NonExistent");
+        var link = Path.Combine(tempFolder, "Link");
+
+        // Should be able to create symlink to non-existent target
+        File.WriteAllText(target, "test");
+        SymbolicLink.Create(link, target);
+        Assert.True(SymbolicLink.Exists(link));
+        Assert.Equal(target, SymbolicLink.GetTarget(link));
+
+        // Clean up
+        SymbolicLink.Delete(link);
+    }
+
+    [Fact]
+    public void Create_MultipleLevelsOfSymlinks()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var file = Path.Combine(tempFolder, "Original.txt");
+        var link1 = Path.Combine(tempFolder, "Link1.txt");
+        var link2 = Path.Combine(tempFolder, "Link2.txt");
+        var link3 = Path.Combine(tempFolder, "Link3.txt");
+
+        File.WriteAllText(file, "Hello");
+
+        // Create chain: link3 -> link2 -> link1 -> file
+        SymbolicLink.Create(link1, file);
+        SymbolicLink.Create(link2, link1);
+        SymbolicLink.Create(link3, link2);
+
+        // All should resolve to the same content
+        Assert.Equal("Hello", File.ReadAllText(link1));
+        Assert.Equal("Hello", File.ReadAllText(link2));
+        Assert.Equal("Hello", File.ReadAllText(link3));
+
+        // Each should point to their immediate target
+        Assert.Equal(file, SymbolicLink.GetTarget(link1));
+        Assert.Equal(link1, SymbolicLink.GetTarget(link2));
+        Assert.Equal(link2, SymbolicLink.GetTarget(link3));
+    }
+
+    [Fact]
+    public void GetTarget_WithTrailingSlash_ShouldWork()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "Target");
+        var link = Path.Combine(tempFolder, "Link");
+
+        Directory.CreateDirectory(target);
+        SymbolicLink.Create(link, target);
+
+        // Should work with and without trailing slash
+        Assert.Equal(target, SymbolicLink.GetTarget(link));
+        Assert.Equal(target, SymbolicLink.GetTarget(link + Path.DirectorySeparatorChar));
+    }
+
+    [Fact]
+    public void Create_WithSpecialCharactersInPath()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "Target With Spaces & Special-Chars");
+        var link = Path.Combine(tempFolder, "Link With Spaces & Special-Chars");
+
+        Directory.CreateDirectory(target);
+        File.WriteAllText(Path.Combine(target, "file.txt"), "content");
+
+        SymbolicLink.Create(link, target);
+        Assert.True(SymbolicLink.Exists(link));
+        Assert.Equal(target, SymbolicLink.GetTarget(link));
+        Assert.Equal("content", File.ReadAllText(Path.Combine(link, "file.txt")));
+    }
+
+    [Fact]
+    public void Create_AbsoluteVsRelativeComparison()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var subdir = Directory.CreateDirectory(Path.Combine(tempFolder, "subdir")).FullName;
+        var target = Path.Combine(tempFolder, "target.txt");
+        var linkAbs = Path.Combine(subdir, "link_abs.txt");
+        var linkRel = Path.Combine(subdir, "link_rel.txt");
+
+        File.WriteAllText(target, "test");
+
+        // Create absolute and relative links
+        SymbolicLink.Create(linkAbs, target, relative: false);
+        SymbolicLink.Create(linkRel, target, relative: true);
+
+        // Both should work
+        Assert.Equal("test", File.ReadAllText(linkAbs));
+        Assert.Equal("test", File.ReadAllText(linkRel));
+
+        // Check targets
+        Assert.Equal(target, SymbolicLink.GetTarget(linkAbs));
+        Assert.Equal(target, SymbolicLink.GetTarget(linkRel));
+
+        // Relative target should be different when requested
+        var relTarget = SymbolicLink.GetTarget(linkRel, relative: true);
+        Assert.Contains("..", relTarget);
+    }
+
+    [Fact]
+    public void FileSymlink_AllImplementationsAgree()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "target.txt");
+        var link = Path.Combine(tempFolder, "link.txt");
+
+        File.WriteAllText(target, "test content");
+
+        // Create with our implementation
+        SymbolicLink.Create(link, target);
+
+        // Verify all implementations agree
+        var ourTarget = SymbolicLink.GetTarget(link);
+        Assert.Equal(target, ourTarget);
+
+        // Compare with NCode.ReparsePoints (Windows only)
+        if (VelopackRuntimeInfo.IsWindows) {
+            var provider = new ReparsePointProvider();
+            var linkInfo = provider.GetLink(link);
+            Assert.Equal(LinkType.Symbolic, linkInfo.Type);
+            Assert.Equal(target, linkInfo.Target);
+        }
+
+#if NET6_0_OR_GREATER
+        var fileInfo = new FileInfo(link);
+        Assert.NotNull(fileInfo.LinkTarget);
+        Assert.Equal(target, Path.GetFullPath(fileInfo.LinkTarget));
+
+        // Test interoperability: create with framework, read with ours
+        var link2 = Path.Combine(tempFolder, "link2.txt");
+        File.CreateSymbolicLink(link2, target);
+        Assert.Equal(target, SymbolicLink.GetTarget(link2));
+#endif
+    }
+
+    [Fact]
+    public void DirectorySymlink_AllImplementationsAgree()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "targetDir");
+        var link = Path.Combine(tempFolder, "linkDir");
+
+        Directory.CreateDirectory(target);
+        File.WriteAllText(Path.Combine(target, "file.txt"), "content");
+
+        // Create with our implementation
+        SymbolicLink.Create(link, target);
+
+        // Verify all implementations agree
+        var ourTarget = SymbolicLink.GetTarget(link);
+        Assert.Equal(target, ourTarget);
+
+        // Compare with NCode.ReparsePoints (Windows only)
+        if (VelopackRuntimeInfo.IsWindows) {
+            var provider = new ReparsePointProvider();
+            var linkInfo = provider.GetLink(link);
+            // Directory symlinks on Windows are actually junctions
+            Assert.True(linkInfo.Type == LinkType.Junction || linkInfo.Type == LinkType.Symbolic);
+            Assert.Equal(target, linkInfo.Target);
+        }
+
+#if NET6_0_OR_GREATER
+        var dirInfo = new DirectoryInfo(link);
+        Assert.NotNull(dirInfo.LinkTarget);
+        Assert.Equal(target, Path.GetFullPath(dirInfo.LinkTarget));
+
+        // Test interoperability: create with framework, read with ours
+        var link2 = Path.Combine(tempFolder, "linkDir2");
+        Directory.CreateSymbolicLink(link2, target);
+        Assert.Equal(target, SymbolicLink.GetTarget(link2));
+#endif
+    }
+
+    [Fact]
+    public void RelativeSymlink_AllImplementationsAgree()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var subdir = Directory.CreateDirectory(Path.Combine(tempFolder, "subdir")).FullName;
+        var target = Path.Combine(tempFolder, "target.txt");
+        var link = Path.Combine(subdir, "link.txt");
+
+        File.WriteAllText(target, "test");
+
+        // Create relative symlink with our implementation
+        SymbolicLink.Create(link, target, relative: true);
+
+        // Verify our implementation handles relative vs absolute correctly
+        var ourAbsoluteTarget = SymbolicLink.GetTarget(link);
+        var ourRelativeTarget = SymbolicLink.GetTarget(link, relative: true);
+        Assert.Equal(target, ourAbsoluteTarget);
+        Assert.Contains("..", ourRelativeTarget);
+
+        // Compare with NCode.ReparsePoints (Windows only)
+        if (VelopackRuntimeInfo.IsWindows) {
+            var provider = new ReparsePointProvider();
+            var linkInfo = provider.GetLink(link);
+            Assert.Equal(LinkType.Symbolic, linkInfo.Type);
+            // NCode returns the raw target path as stored in the symlink
+            // For relative symlinks, this will be the relative path, not absolute
+            Assert.Equal(ourRelativeTarget, linkInfo.Target);
+        }
+
+#if NET6_0_OR_GREATER
+        var fileInfo = new FileInfo(link);
+        Assert.NotNull(fileInfo.LinkTarget);
+        // Framework returns the relative path for relative symlinks
+        Assert.Contains("..", fileInfo.LinkTarget);
+        Assert.Equal(fileInfo.LinkTarget, ourRelativeTarget);
+#endif
+    }
+
+    [Fact]
+    public void MultipleLevelsOfSymlinks_AllImplementationsAgree()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var file = Path.Combine(tempFolder, "original.txt");
+        var link1 = Path.Combine(tempFolder, "link1.txt");
+        var link2 = Path.Combine(tempFolder, "link2.txt");
+
+        File.WriteAllText(file, "content");
+
+        // Create chain: link2 -> link1 -> file
+        SymbolicLink.Create(link1, file);
+        SymbolicLink.Create(link2, link1);
+
+        // Verify our implementation
+        Assert.Equal(file, SymbolicLink.GetTarget(link1));
+        Assert.Equal(link1, SymbolicLink.GetTarget(link2));
+
+        // Verify content access works through the chain
+        Assert.Equal("content", File.ReadAllText(link1));
+        Assert.Equal("content", File.ReadAllText(link2));
+
+        // Compare with NCode.ReparsePoints (Windows only)
+        if (VelopackRuntimeInfo.IsWindows) {
+            var provider = new ReparsePointProvider();
+            var link1Info = provider.GetLink(link1);
+            var link2Info = provider.GetLink(link2);
+            Assert.Equal(LinkType.Symbolic, link1Info.Type);
+            Assert.Equal(LinkType.Symbolic, link2Info.Type);
+            Assert.Equal(file, link1Info.Target);
+            Assert.Equal(link1, link2Info.Target);
+        }
+
+#if NET6_0_OR_GREATER
+        var fileInfo1 = new FileInfo(link1);
+        var fileInfo2 = new FileInfo(link2);
+        Assert.NotNull(fileInfo1.LinkTarget);
+        Assert.NotNull(fileInfo2.LinkTarget);
+        Assert.Equal(file, Path.GetFullPath(fileInfo1.LinkTarget));
+        Assert.Equal(link1, Path.GetFullPath(fileInfo2.LinkTarget));
+
+        // Test ResolveLinkTarget for final resolution
+        var finalTarget = fileInfo2.ResolveLinkTarget(true);
+        Assert.Equal(file, finalTarget?.FullName);
+#endif
+    }
+
+    [Fact]
+    public void Delete_OnlyDeletesLinkNotTarget()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "target.txt");
+        var link = Path.Combine(tempFolder, "link.txt");
+
+        File.WriteAllText(target, "important data");
+        SymbolicLink.Create(link, target);
+
+        // Delete the link
+        SymbolicLink.Delete(link);
+
+        // Link should be gone, but target should remain
+        Assert.False(File.Exists(link));
+        Assert.False(SymbolicLink.Exists(link));
+        Assert.True(File.Exists(target));
+        Assert.Equal("important data", File.ReadAllText(target));
+    }
+
+    [SkippableFact]
+    public void Exists_ReturnsFalseForHardLink()
+    {
+        Skip.IfNot(VelopackRuntimeInfo.IsWindows);
+
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target = Path.Combine(tempFolder, "target.txt");
+        var hardLink = Path.Combine(tempFolder, "hardlink.txt");
+
+        File.WriteAllText(target, "test");
+
+        // Create hard link using P/Invoke
+        if (!CreateHardLink(hardLink, target, IntPtr.Zero)) {
+            // Skip test if hard link creation fails (may need elevation)
+            return;
+        }
+
+        // Hard link should exist as a file but not as a symbolic link
+        Assert.True(File.Exists(hardLink));
+        Assert.False(SymbolicLink.Exists(hardLink));
+    }
+
+    [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
+    static extern bool CreateHardLink(string lpFileName, string lpExistingFileName, IntPtr lpSecurityAttributes);
+
+    [Fact]
+    public void GetTarget_ErrorMessages_AreDescriptive()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var regularFile = Path.Combine(tempFolder, "regular.txt");
+        var regularDir = Path.Combine(tempFolder, "regularDir");
+        var nonExistent = Path.Combine(tempFolder, "nonExistent");
+
+        File.WriteAllText(regularFile, "test");
+        Directory.CreateDirectory(regularDir);
+
+        // Test various error conditions
+        var ex1 = Assert.Throws<IOException>(() => SymbolicLink.GetTarget(regularFile));
+        Assert.Contains("junction", ex1.Message.ToLower());
+
+        var ex2 = Assert.Throws<IOException>(() => SymbolicLink.GetTarget(regularDir));
+        Assert.Contains("junction", ex2.Message.ToLower());
+
+        var ex3 = Assert.Throws<IOException>(() => SymbolicLink.GetTarget(nonExistent));
+        Assert.Contains("does not exist", ex3.Message.ToLower());
+    }
+
+    [Fact]
+    public void Create_OverwriteExistingSymlink()
+    {
+        using var _1 = TempUtil.GetTempDirectory(out var tempFolder);
+        var target1 = Path.Combine(tempFolder, "target1.txt");
+        var target2 = Path.Combine(tempFolder, "target2.txt");
+        var link = Path.Combine(tempFolder, "link.txt");
+
+        File.WriteAllText(target1, "content1");
+        File.WriteAllText(target2, "content2");
+
+        // Create initial symlink
+        SymbolicLink.Create(link, target1);
+        Assert.Equal("content1", File.ReadAllText(link));
+
+        // Overwrite with new target
+        SymbolicLink.Create(link, target2, overwrite: true);
+        Assert.Equal("content2", File.ReadAllText(link));
+        Assert.Equal(target2, SymbolicLink.GetTarget(link));
+    }
 }