Fix version height computed as 0 when project path has non-canonical casing (#1244)

* Initial plan

* Implement case-insensitive path matching support in managed git implementation

Co-authored-by: AArnott <[email protected]>

* Add comprehensive tests for case-insensitive path matching functionality

Co-authored-by: AArnott <[email protected]>

* fix stylecop issues

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: AArnott <[email protected]>
Co-authored-by: Andrew Arnott <[email protected]>

Author: Copilot

src/NerdBank.GitVersioning/ManagedGit/GitRepository.cs

@@ -95,9 +95,10 @@ public GitRepository(string workingDirectory, string gitDirectory, string common
         this.objectPathBuffer[pathLengthInChars - 1] = '\0'; // Make sure to initialize with zeros
 
         this.packs = new Lazy<ReadOnlyMemory<GitPack>>(this.LoadPacks);
-    }
 
-    // TODO: read from Git settings
+        // Read git configuration to determine case sensitivity
+        this.IgnoreCase = this.ReadIgnoreCaseFromConfig();
+    }
 
     /// <summary>
     /// Gets the encoding used by this Git repository.
@@ -518,7 +519,21 @@ public GitObjectId GetTreeEntry(GitObjectId treeId, ReadOnlySpan<byte> nodeName)
             throw new GitException($"The tree {treeId} was not found in this repository.") { ErrorCode = GitException.ErrorCodes.ObjectNotFound };
         }
 
-        return GitTreeStreamingReader.FindNode(treeStream, nodeName);
+        // Try case-sensitive search first
+        GitObjectId result = GitTreeStreamingReader.FindNode(treeStream, nodeName, ignoreCase: false);
+
+        // If not found and repository is configured for case-insensitive matching, try case-insensitive search
+        if (result == GitObjectId.Empty && this.IgnoreCase)
+        {
+            // Get a fresh stream for the second search since we can't reset position on ZLibStream
+            using Stream? treeStream2 = this.GetObjectBySha(treeId, "tree");
+            if (treeStream2 is not null)
+            {
+                result = GitTreeStreamingReader.FindNode(treeStream2, nodeName, ignoreCase: true);
+            }
+        }
+
+        return result;
     }
 
     /// <summary>
@@ -767,6 +782,119 @@ private static bool TryConvertHexStringToByteArray(string hexString, Span<byte>
         return true;
     }
 
+    /// <summary>
+    /// Attempts to read the core.ignorecase setting from a git config file.
+    /// </summary>
+    /// <param name="configPath">Path to the git config file.</param>
+    /// <param name="ignoreCase">The value of core.ignorecase if found.</param>
+    /// <returns>True if the setting was found and parsed successfully.</returns>
+    private static bool TryReadIgnoreCaseFromConfigFile(string configPath, out bool ignoreCase)
+    {
+        ignoreCase = false;
+        try
+        {
+            string[] lines = File.ReadAllLines(configPath);
+            bool inCoreSection = false;
+
+            foreach (string line in lines)
+            {
+                string trimmedLine = line.Trim();
+
+                // Check for section headers
+                if (trimmedLine.StartsWith("[") && trimmedLine.EndsWith("]"))
+                {
+                    string sectionName = trimmedLine.Substring(1, trimmedLine.Length - 2).Trim();
+                    inCoreSection = string.Equals(sectionName, "core", StringComparison.OrdinalIgnoreCase);
+                    continue;
+                }
+
+                // If we're in the [core] section, look for ignorecase setting
+                if (inCoreSection && trimmedLine.Contains("="))
+                {
+                    int equalIndex = trimmedLine.IndexOf('=');
+                    string key = trimmedLine.Substring(0, equalIndex).Trim();
+                    string value = trimmedLine.Substring(equalIndex + 1).Trim();
+
+                    if (string.Equals(key, "ignorecase", StringComparison.OrdinalIgnoreCase))
+                    {
+                        ignoreCase = string.Equals(value, "true", StringComparison.OrdinalIgnoreCase);
+                        return true;
+                    }
+                }
+            }
+        }
+        catch
+        {
+            // Ignore errors and return false
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// Gets the path to the global git config file.
+    /// </summary>
+    /// <returns>The path to the global config file, or null if not found.</returns>
+    private static string? GetGlobalConfigPath()
+    {
+        try
+        {
+            // Try common locations for global git config
+            string? homeDir = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
+            if (!string.IsNullOrEmpty(homeDir))
+            {
+                string gitConfigPath = Path.Combine(homeDir, ".gitconfig");
+                if (File.Exists(gitConfigPath))
+                {
+                    return gitConfigPath;
+                }
+            }
+        }
+        catch
+        {
+            // Ignore errors
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Reads the core.ignorecase setting from git configuration.
+    /// </summary>
+    /// <returns>True if case should be ignored, false otherwise.</returns>
+    private bool ReadIgnoreCaseFromConfig()
+    {
+        try
+        {
+            // Try to read from .git/config first (repository-specific)
+            string repoConfigPath = Path.Combine(this.GitDirectory, "config");
+            if (File.Exists(repoConfigPath))
+            {
+                if (TryReadIgnoreCaseFromConfigFile(repoConfigPath, out bool ignoreCase))
+                {
+                    return ignoreCase;
+                }
+            }
+
+            // Fall back to global config if repo config doesn't have the setting
+            string? globalConfigPath = GetGlobalConfigPath();
+            if (globalConfigPath is object && File.Exists(globalConfigPath))
+            {
+                if (TryReadIgnoreCaseFromConfigFile(globalConfigPath, out bool ignoreCase))
+                {
+                    return ignoreCase;
+                }
+            }
+        }
+        catch
+        {
+            // If we can't read config, default to case-sensitive
+        }
+
+        // Default to case-sensitive (false) if no config found or error occurred
+        return false;
+    }
+
     private bool TryGetObjectByPath(GitObjectId sha, string objectType, [NotNullWhen(true)] out Stream? value)
     {
         sha.CopyAsHex(0, 1, this.objectPathBuffer.AsSpan(this.ObjectDirectory.Length + 1, 2));

src/NerdBank.GitVersioning/ManagedGit/GitTreeStreamingReader.cs

@@ -25,6 +25,24 @@ public class GitTreeStreamingReader
     /// The <see cref="GitObjectId"/> of the requested node.
     /// </returns>
     public static GitObjectId FindNode(Stream stream, ReadOnlySpan<byte> name)
+        => FindNode(stream, name, ignoreCase: false);
+
+    /// <summary>
+    /// Finds a specific node in a git tree.
+    /// </summary>
+    /// <param name="stream">
+    /// A <see cref="Stream"/> which represents the git tree.
+    /// </param>
+    /// <param name="name">
+    /// The name of the node to find, in it UTF-8 representation.
+    /// </param>
+    /// <param name="ignoreCase">
+    /// Whether to ignore case when matching node names.
+    /// </param>
+    /// <returns>
+    /// The <see cref="GitObjectId"/> of the requested node.
+    /// </returns>
+    public static GitObjectId FindNode(Stream stream, ReadOnlySpan<byte> name, bool ignoreCase)
     {
         byte[] buffer = ArrayPool<byte>.Shared.Rent((int)stream.Length);
         var contents = new Span<byte>(buffer, 0, (int)stream.Length);
@@ -44,7 +62,11 @@ public static GitObjectId FindNode(Stream stream, ReadOnlySpan<byte> name)
 
             Span<byte> currentName = contents.Slice(modeLength, fileNameEnds - modeLength);
 
-            if (currentName.SequenceEqual(name))
+            bool matches = ignoreCase
+                ? currentName.SequenceEqual(name) || CompareIgnoreCase(currentName, name)
+                : currentName.SequenceEqual(name);
+
+            if (matches)
             {
                 value = GitObjectId.Parse(contents.Slice(fileNameEnds + 1, 20));
                 break;
@@ -59,4 +81,42 @@ public static GitObjectId FindNode(Stream stream, ReadOnlySpan<byte> name)
 
         return value;
     }
+
+    /// <summary>
+    /// Compares two byte sequences case-insensitively (assuming UTF-8 encoding with ASCII characters).
+    /// </summary>
+    /// <param name="a">First byte sequence.</param>
+    /// <param name="b">Second byte sequence.</param>
+    /// <returns>True if the sequences are equal ignoring case.</returns>
+    private static bool CompareIgnoreCase(ReadOnlySpan<byte> a, ReadOnlySpan<byte> b)
+    {
+        if (a.Length != b.Length)
+        {
+            return false;
+        }
+
+        for (int i = 0; i < a.Length; i++)
+        {
+            byte aChar = a[i];
+            byte bChar = b[i];
+
+            // Convert to lowercase for ASCII characters
+            if (aChar >= 'A' && aChar <= 'Z')
+            {
+                aChar = (byte)(aChar + 32);
+            }
+
+            if (bChar >= 'A' && bChar <= 'Z')
+            {
+                bChar = (byte)(bChar + 32);
+            }
+
+            if (aChar != bChar)
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }

test/Nerdbank.GitVersioning.Tests/ManagedGit/GitTreeStreamingReaderTests.cs

@@ -29,4 +29,37 @@ public void FindTreeTest()
             Assert.Equal("ec8e91fc4ad13d6a214584330f26d7a05495c8cc", blobObjectId.ToString());
         }
     }
+
+    [Fact]
+    public void FindBlobCaseInsensitiveTest()
+    {
+        using (Stream stream = TestUtilities.GetEmbeddedResource(@"ManagedGit\tree.bin"))
+        {
+            // Try to find "version.json" with different casing
+            GitObjectId blobObjectId = GitTreeStreamingReader.FindNode(stream, Encoding.UTF8.GetBytes("VERSION.JSON"), ignoreCase: true);
+            Assert.Equal("59552a5eed6779aa4e5bb4dc96e80f36bb6e7380", blobObjectId.ToString());
+        }
+    }
+
+    [Fact]
+    public void FindBlobCaseSensitiveFailsWithDifferentCasing()
+    {
+        using (Stream stream = TestUtilities.GetEmbeddedResource(@"ManagedGit\tree.bin"))
+        {
+            // Try to find "version.json" with different casing using case-sensitive search
+            GitObjectId blobObjectId = GitTreeStreamingReader.FindNode(stream, Encoding.UTF8.GetBytes("VERSION.JSON"), ignoreCase: false);
+            Assert.Equal(GitObjectId.Empty, blobObjectId);
+        }
+    }
+
+    [Fact]
+    public void FindTreeCaseInsensitiveTest()
+    {
+        using (Stream stream = TestUtilities.GetEmbeddedResource(@"ManagedGit\tree.bin"))
+        {
+            // Try to find "tools" with different casing
+            GitObjectId blobObjectId = GitTreeStreamingReader.FindNode(stream, Encoding.UTF8.GetBytes("TOOLS"), ignoreCase: true);
+            Assert.Equal("ec8e91fc4ad13d6a214584330f26d7a05495c8cc", blobObjectId.ToString());
+        }
+    }
 }

test/Nerdbank.GitVersioning.Tests/VersionFileTests.cs

@@ -645,6 +645,82 @@ public void GetVersion_ReadNuGetPackageVersionSettings_Precision(VersionOptions.
         Assert.Equal(precision, versionOptions.NuGetPackageVersion.Precision);
     }
 
+    [Fact]
+    public void GetVersion_CaseInsensitivePathMatching_Simple()
+    {
+        // Simple test to debug the issue
+        this.InitializeSourceControl();
+
+        // Create a version.json file using the standard test method
+        this.WriteVersionFile(new VersionOptions { Version = new SemanticVersion("1.0.0") });
+
+        // Test reading from the root - this should work
+        VersionOptions actualVersionOptions = this.GetVersionOptions();
+        Assert.NotNull(actualVersionOptions);
+        Assert.Equal("1.0.0", actualVersionOptions.Version.ToString());
+    }
+
+    [Fact]
+    public void GetVersion_CaseInsensitivePathMatching()
+    {
+        // This test verifies that when a project's repo-relative path case doesn't match
+        // what git records, we still find the version.json file through case-insensitive fallback.
+        this.InitializeSourceControl();
+
+        // Create a version.json file in a subdirectory using the standard method
+        string subDirPath = "MyProject";
+        this.WriteVersionFile(
+            new VersionOptions
+            {
+                Version = new SemanticVersion("1.2.3"),
+                VersionHeightOffset = 10,
+            },
+            subDirPath);
+
+        // Configure the git repository for case-insensitive matching
+        // This simulates a Windows/macOS environment where the filesystem is case-insensitive
+        string gitConfigPath = Path.Combine(this.RepoPath, ".git", "config");
+        string configContent = File.ReadAllText(gitConfigPath);
+        if (!configContent.Contains("[core]"))
+        {
+            configContent += "\n[core]\n\tignorecase = true\n";
+        }
+        else if (!configContent.Contains("ignorecase"))
+        {
+            configContent = configContent.Replace("[core]", "[core]\n\tignorecase = true");
+        }
+
+        File.WriteAllText(gitConfigPath, configContent);
+
+        // First test: Get the version from the actual path with correct casing
+        VersionOptions actualVersionOptions = this.GetVersionOptions(subDirPath);
+
+        // Verify we found the version file and it has the expected version
+        Assert.NotNull(actualVersionOptions);
+        Assert.Equal("1.2.3", actualVersionOptions.Version.ToString());
+        Assert.Equal(10, actualVersionOptions.VersionHeightOffset);
+
+        // Second test: Now test with different casing in the path - this should work
+        // when core.ignorecase is true, because GetTreeEntry should fall back
+        // to case-insensitive matching
+        VersionOptions actualVersionOptionsWithDifferentCase = this.GetVersionOptions("myproject");
+
+        // This should also find the version file despite the case difference
+        // NOTE: This currently only works for the managed implementation, not LibGit2
+        if (this is VersionFileManagedTests)
+        {
+            Assert.NotNull(actualVersionOptionsWithDifferentCase);
+            Assert.Equal("1.2.3", actualVersionOptionsWithDifferentCase.Version.ToString());
+            Assert.Equal(10, actualVersionOptionsWithDifferentCase.VersionHeightOffset);
+        }
+        else
+        {
+            // LibGit2 implementation doesn't yet support case-insensitive fallback
+            // This test documents the current limitation
+            Assert.Null(actualVersionOptionsWithDifferentCase);
+        }
+    }
+
     private void AssertPathHasVersion(string committish, string absolutePath, VersionOptions expected)
     {
         VersionOptions actual = this.GetVersionOptions(absolutePath, committish);