Populate RepositoryBranch

docs/README.md

@@ -143,6 +143,11 @@ The default value is `true`. Set to `false` to suppress publishing `SourceRevisi
 Set by target `InitializeSourceControlInformationFromSourceControlManager` and consumed by NuGet `Pack` target and `GenerateAssemblyInfo` target. 
 May be used by custom targets that need this information.
 
+### SourceBranchName
+
+Set by target `InitializeSourceControlInformationFromSourceControlManager` and consumed by NuGet `Pack` target.
+May be used by custom targets that need this information.
+
 ### EnableSourceLink
 
 This property is implicitly set to `true` by a Source Link package. Including a Source Link package thus enables Source Link generation unless explicitly disabled by the project by setting this property to `false`.
@@ -165,6 +170,7 @@ Additional source-control specific metadata may be defined (depends on the sourc
 For example, for Git:
 
 - _RepositoryUrl_: e.g. `http://github.com/dotnet/corefx`
+- _BranchName_: e.g. `refs/heads/main` (may be null if branch is in a detached HEAD state)
 
 For TFVC:
 

src/Common/Utilities/Names.cs

@@ -18,6 +18,7 @@ internal static class SourceRoot
             public const string NestedRoot = nameof(NestedRoot);
             public const string MappedPath = nameof(MappedPath);
             public const string SourceLinkUrl = nameof(SourceLinkUrl);
+            public const string BranchName = nameof(BranchName);
 
             public const string MappedPathFullName = nameof(SourceRoot) + "." + nameof(MappedPath);
             public const string SourceLinkUrlFullName = nameof(SourceRoot) + "." + nameof(SourceLinkUrl);

src/Microsoft.Build.Tasks.Git.UnitTests/GitOperationsTests.cs

@@ -25,6 +25,7 @@ private GitRepository CreateRepository(
             string? workingDir = null,
             GitConfig? config = null,
             string? commitSha = null,
+            string? branchName = null,
             ImmutableArray<GitSubmodule> submodules = default,
             GitIgnore? ignore = null)
         {
@@ -39,7 +40,8 @@ private GitRepository CreateRepository(
                 submodules.IsDefault ? ImmutableArray<GitSubmodule>.Empty : submodules,
                 submoduleDiagnostics: ImmutableArray<string>.Empty,
                 ignore ?? new GitIgnore(root: null, workingDir, ignoreCase: false),
-                commitSha);
+                commitSha,
+                branchName);
         }
 
         private GitSubmodule CreateSubmodule(string name, string relativePath, string url, string? headCommitSha, string? containingRepositoryWorkingDir = null)
@@ -316,6 +318,24 @@ public void GetSourceRoots_RepoWithoutCommits(bool warnOnMissingCommit)
             AssertEx.Equal(warnOnMissingCommit ? new[] { Resources.RepositoryHasNoCommit } : Array.Empty<string>(), warnings.Select(TestUtilities.InspectDiagnostic));
         }
 
+        [Fact]
+        public void GetSourceRoots_BranchName()
+        {
+            var repo = CreateRepository(
+                commitSha: "0000000000000000000000000000000000000000",
+                branchName: "refs/heads/abc");
+
+            var warnings = new List<(string, object?[])>();
+            var items = GitOperations.GetSourceRoots(repo, remoteName: null, warnOnMissingCommitOrUnsupportedUri: false, (message, args) => warnings.Add((message, args)));
+
+            AssertEx.Equal(new[]
+{
+                $@"'{_workingDir}{s}' SourceControl='git' RevisionId='0000000000000000000000000000000000000000' BranchName='refs/heads/abc'",
+            }, items.Select(TestUtilities.InspectSourceRoot));
+
+            AssertEx.Equal(Array.Empty<string>(), warnings.Select(TestUtilities.InspectDiagnostic));
+        }
+
         [Fact]
         public void GetSourceRoots_RepoWithCommits_WithoutUrl()
         {
@@ -468,7 +488,7 @@ public void GetSourceRoots_RelativeSubmodulePath(bool warnOnMissingCommitOrUnsup
                 Assert.Empty(warnings);
             }
         }
-		
+
 		private static GitOperations.DirectoryNode CreateNode(string name, string? submoduleWorkingDirectory, List<GitOperations.DirectoryNode>? children = null)
             => new GitOperations.DirectoryNode(name, children ?? new List<GitOperations.DirectoryNode>())
             {

src/Microsoft.Build.Tasks.Git.UnitTests/GitRepositoryTests.cs

@@ -539,5 +539,37 @@ public void GetSubmoduleHeadCommitSha_NoGitFile()
 
             Assert.Null(GitRepository.GetSubmoduleReferenceResolver(submoduleWorkingDir.Path)?.ResolveHeadReference());
         }
+
+        [Fact]
+        public void GetHeadBranchName()
+        {
+            using var temp = new TempRoot();
+
+            var commonDir = temp.CreateDirectory();
+            var refsHeadsDir = commonDir.CreateDirectory("refs").CreateDirectory("heads");
+            refsHeadsDir.CreateFile("master").WriteAllText("0000000000000000000000000000000000000000 \t\v\r\n");
+
+            var gitDir = temp.CreateDirectory();
+            gitDir.CreateFile("HEAD").WriteAllText("ref: refs/heads/master \t\v\r\n");
+
+            var repository = new GitRepository(GitEnvironment.Empty, GitConfig.Empty, gitDir.Path, commonDir.Path, workingDirectory: null);
+            Assert.Equal("refs/heads/master", repository.GetBranchName());
+        }
+
+        [Fact]
+        public void GetHeadBranchName_DetachedHead()
+        {
+            using var temp = new TempRoot();
+
+            var commonDir = temp.CreateDirectory();
+            var refsHeadsDir = commonDir.CreateDirectory("refs").CreateDirectory("heads");
+            refsHeadsDir.CreateFile("master").WriteAllText("0000000000000000000000000000000000000000 \t\v\r\n");
+
+            var gitDir = temp.CreateDirectory();
+            gitDir.CreateFile("HEAD").WriteAllText("0000000000000000000000000000000000000000 \t\v\r\n");
+
+            var repository = new GitRepository(GitEnvironment.Empty, GitConfig.Empty, gitDir.Path, commonDir.Path, workingDirectory: null);
+            Assert.Null(repository.GetBranchName());
+        }
     }
 }

src/Microsoft.Build.Tasks.Git.UnitTests/TestUtilities.cs

@@ -17,14 +17,16 @@ public static string InspectSourceRoot(ITaskItem sourceRoot)
             var containingRoot = sourceRoot.GetMetadata("ContainingRoot");
             var scmRepositoryUrl = sourceRoot.GetMetadata("ScmRepositoryUrl");
             var sourceLinkUrl = sourceRoot.GetMetadata("SourceLinkUrl");
+            var branchName = sourceRoot.GetMetadata("BranchName");
 
             return $"'{sourceRoot.ItemSpec}'" +
               (string.IsNullOrEmpty(sourceControl) ? "" : $" SourceControl='{sourceControl}'") +
               (string.IsNullOrEmpty(revisionId) ? "" : $" RevisionId='{revisionId}'") +
               (string.IsNullOrEmpty(nestedRoot) ? "" : $" NestedRoot='{nestedRoot}'") +
               (string.IsNullOrEmpty(containingRoot) ? "" : $" ContainingRoot='{containingRoot}'") +
               (string.IsNullOrEmpty(scmRepositoryUrl) ? "" : $" ScmRepositoryUrl='{scmRepositoryUrl}'") +
-              (string.IsNullOrEmpty(sourceLinkUrl) ? "" : $" SourceLinkUrl='{sourceLinkUrl}'");
+              (string.IsNullOrEmpty(sourceLinkUrl) ? "" : $" SourceLinkUrl='{sourceLinkUrl}'") +
+              (string.IsNullOrEmpty(branchName) ? "" : $" BranchName='{branchName}'");
         }
 
         public static string InspectDiagnostic((string Message, object?[] Args) warning)

src/Microsoft.Build.Tasks.Git/GitDataReader/GitReferenceResolver.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 
@@ -152,23 +153,40 @@ internal static ImmutableDictionary<string, string> ReadPackedReferences(TextRea
         public string? ResolveHeadReference()
             => ResolveReference(ReadReferenceFromFile(Path.Combine(_gitDirectory, GitRepository.GitHeadFileName)));
 
+        public string? GetBranchForHead()
+        {
+            string reference = ReadReferenceFromFile(Path.Combine(_gitDirectory, GitRepository.GitHeadFileName));
+
+            return TryGetReferenceName(reference, out var name) ? name : null;
+        }
+
         public string? ResolveReference(string reference)
         {
             HashSet<string>? lazyVisitedReferences = null;
             return ResolveReference(reference, ref lazyVisitedReferences);
         }
 
+        private static bool TryGetReferenceName(string reference, [NotNullWhen(true)] out string? name)
+        {
+            const string refPrefix = "ref: ";
+            if (reference.StartsWith(refPrefix + RefsPrefix, StringComparison.Ordinal))
+            {
+                name = reference.Substring(refPrefix.Length);
+                return true;
+            }
+
+            name = null;
+            return false;
+        }
+
         /// <exception cref="IOException"/>
         /// <exception cref="InvalidDataException"/>
         private string? ResolveReference(string reference, ref HashSet<string>? lazyVisitedReferences)
         {
             // See https://git-scm.com/docs/gitrepository-layout#Documentation/gitrepository-layout.txt-HEAD
 
-            const string refPrefix = "ref: ";
-            if (reference.StartsWith(refPrefix + RefsPrefix, StringComparison.Ordinal))
+            if (TryGetReferenceName(reference, out var symRef))
             {
-                var symRef = reference.Substring(refPrefix.Length);
-
                 if (lazyVisitedReferences != null && !lazyVisitedReferences.Add(symRef))
                 {
                     // infinite recursion

src/Microsoft.Build.Tasks.Git/GitDataReader/GitRepository.cs

@@ -51,6 +51,7 @@ internal sealed class GitRepository
         private readonly Lazy<(ImmutableArray<GitSubmodule> Submodules, ImmutableArray<string> Diagnostics)> _lazySubmodules;
         private readonly Lazy<GitIgnore> _lazyIgnore;
         private readonly Lazy<string?> _lazyHeadCommitSha;
+        private readonly Lazy<string?> _lazyBranchName;
         private readonly GitReferenceResolver _referenceResolver;
 
         internal GitRepository(GitEnvironment environment, GitConfig config, string gitDirectory, string commonDirectory, string? workingDirectory)
@@ -71,6 +72,7 @@ internal GitRepository(GitEnvironment environment, GitConfig config, string gitD
             _lazySubmodules = new Lazy<(ImmutableArray<GitSubmodule>, ImmutableArray<string>)>(ReadSubmodules);
             _lazyIgnore = new Lazy<GitIgnore>(LoadIgnore);
             _lazyHeadCommitSha = new Lazy<string?>(ReadHeadCommitSha);
+            _lazyBranchName = new Lazy<string?>(ReadBranchName);
         }
 
         // test only
@@ -83,12 +85,14 @@ internal GitRepository(
             ImmutableArray<GitSubmodule> submodules,
             ImmutableArray<string> submoduleDiagnostics,
             GitIgnore ignore,
-            string? headCommitSha)
+            string? headCommitSha,
+            string? branchName)
             : this(environment, config, gitDirectory, commonDirectory, workingDirectory)
         {
             _lazySubmodules = new Lazy<(ImmutableArray<GitSubmodule>, ImmutableArray<string>)>(() => (submodules, submoduleDiagnostics));
             _lazyIgnore = new Lazy<GitIgnore>(() => ignore);
             _lazyHeadCommitSha = new Lazy<string?>(() => headCommitSha);
+            _lazyBranchName = new Lazy<string?>(() => branchName);
         }        
 
         /// <summary>
@@ -181,6 +185,12 @@ public static GitRepository OpenRepository(GitRepositoryLocation location, GitEn
         private string? ReadHeadCommitSha()
             => _referenceResolver.ResolveHeadReference();
 
+        public string? GetBranchName()
+            => _lazyBranchName.Value;
+
+        private string? ReadBranchName()
+            => _referenceResolver.GetBranchForHead();
+
         /// <summary>
         /// Creates <see cref="GitReferenceResolver"/> for a submodule located in the specified <paramref name="submoduleWorkingDirectoryFullPath"/>.
         /// </summary>

src/Microsoft.Build.Tasks.Git/GitOperations.cs

@@ -251,6 +251,7 @@ public static ITaskItem[] GetSourceRoots(GitRepository repository, string? remot
             {
                 // Don't report a warning since it has already been reported by GetRepositoryUrl task.
                 string? repositoryUrl = GetRepositoryUrl(repository, remoteName, logWarning: null);
+                string? branchName = repository.GetBranchName();
 
                 // Item metadata are stored msbuild-escaped. GetMetadata unescapes, SetMetadata stores the value as specified.
                 // Escape msbuild special characters so that URL escapes in the URL are preserved when the URL is read by GetMetadata.
@@ -259,6 +260,7 @@ public static ITaskItem[] GetSourceRoots(GitRepository repository, string? remot
                 item.SetMetadata(Names.SourceRoot.SourceControl, SourceControlName);
                 item.SetMetadata(Names.SourceRoot.ScmRepositoryUrl, Evaluation.ProjectCollection.Escape(repositoryUrl));
                 item.SetMetadata(Names.SourceRoot.RevisionId, revisionId);
+                item.SetMetadata(Names.SourceRoot.BranchName, Evaluation.ProjectCollection.Escape(branchName));
                 result.Add(item);
             }
             else if (warnOnMissingCommitOrUnsupportedUri)

src/Microsoft.Build.Tasks.Git/LocateRepository.cs

@@ -44,6 +44,12 @@ public sealed class LocateRepository : RepositoryTask
         [Output]
         public string? RevisionId { get; private set; }
 
+        /// <summary>
+        /// Branch name.
+        /// </summary>
+        [Output]
+        public string? BranchName { get; private set; }
+
         protected override string? GetRepositoryId() => null;
         protected override string GetInitialPath() => Path!;
 
@@ -56,6 +62,7 @@ private protected override void Execute(GitRepository repository)
             Url = GitOperations.GetRepositoryUrl(repository, RemoteName, warnOnMissingOrUnsupportedRemote: !NoWarnOnMissingInfo, Log.LogWarning);
             Roots = GitOperations.GetSourceRoots(repository, RemoteName, warnOnMissingCommitOrUnsupportedUri: !NoWarnOnMissingInfo, Log.LogWarning);
             RevisionId = repository.GetHeadCommitSha();
+            BranchName = repository.GetBranchName();
         }
     }
 }

src/Microsoft.Build.Tasks.Git/build/Microsoft.Build.Tasks.Git.targets

@@ -22,7 +22,7 @@
       Reports a warning if the given project doesn't belong to a repository under source control,
       unless the targets were implicily imported from an SDK without a package reference.
     -->
-    <Microsoft.Build.Tasks.Git.LocateRepository 
+    <Microsoft.Build.Tasks.Git.LocateRepository
       Path="$(MSBuildProjectDirectory)"
       RemoteName="$(GitRepositoryRemoteName)"
       ConfigurationScope="$(GitRepositoryConfigurationScope)"
@@ -32,6 +32,7 @@
       <Output TaskParameter="Url" PropertyName="ScmRepositoryUrl" />
       <Output TaskParameter="Roots" ItemName="SourceRoot" />
       <Output TaskParameter="RevisionId" PropertyName="SourceRevisionId" Condition="'$(SourceRevisionId)' == ''" />
+      <Output TaskParameter="BranchName" PropertyName="SourceBranchName" />
     </Microsoft.Build.Tasks.Git.LocateRepository>
 
     <PropertyGroup>

src/SourceLink.Git.IntegrationTests/AzureDevOpsServerTests.cs

@@ -43,6 +43,7 @@ public void FullValidation_Https()
                 {
                     "@(SourceRoot)",
                     "@(SourceRoot->'%(SourceLinkUrl)')",
+                    "@(SourceRoot->'%(BranchName)')",
                     "$(SourceLink)",
                     "$(PrivateRepositoryUrl)",
                     "$(RepositoryUrl)"
@@ -52,6 +53,7 @@ public void FullValidation_Https()
                     NuGetPackageFolders,
                     ProjectSourceRoot,
                     $"https://tfs.{TestStrings.DomainName}.local:8080/tfs/DefaultCollection/project/_apis/git/repositories/{repoName}/items?api-version=1.0&versionType=commit&version={commitSha}&path=/*",
+                    "refs/heads/main",
                     s_relativeSourceLinkJsonPath,
                     $"https://tfs.{TestStrings.DomainName}.local:8080/tfs/DefaultCollection/project/_git/{repoName}",
                     $"https://tfs.{TestStrings.DomainName}.local:8080/tfs/DefaultCollection/project/_git/{repoName}",
@@ -101,6 +103,7 @@ public void FullValidation_Ssh()
                 {
                     "@(SourceRoot)",
                     "@(SourceRoot->'%(SourceLinkUrl)')",
+                    "@(SourceRoot->'%(BranchName)')",
                     "$(SourceLink)",
                     "$(PrivateRepositoryUrl)",
                     "$(RepositoryUrl)"
@@ -110,6 +113,7 @@ public void FullValidation_Ssh()
                     NuGetPackageFolders,
                     ProjectSourceRoot,
                     $"https://tfs.{TestStrings.DomainName}.local/tfs/DefaultCollection/project/_apis/git/repositories/{repoName}/items?api-version=1.0&versionType=commit&version={commitSha}&path=/*",
+                    "refs/heads/main",
                     s_relativeSourceLinkJsonPath,
                     $"https://tfs.{TestStrings.DomainName}.local/tfs/DefaultCollection/project/_git/{repoName}",
                     $"https://tfs.{TestStrings.DomainName}.local/tfs/DefaultCollection/project/_git/{repoName}",

src/SourceLink.Git.IntegrationTests/AzureReposTests.cs

@@ -43,6 +43,7 @@ public void FullValidation_Https(string host)
                 {
                     "@(SourceRoot)",
                     "@(SourceRoot->'%(SourceLinkUrl)')",
+                    "@(SourceRoot->'%(BranchName)')",
                     "$(SourceLink)",
                     "$(PrivateRepositoryUrl)",
                     "$(RepositoryUrl)"
@@ -52,6 +53,7 @@ public void FullValidation_Https(string host)
                     NuGetPackageFolders,
                     ProjectSourceRoot,
                     $"https://test.{host}/test-org/_apis/git/repositories/{repoName}/items?api-version=1.0&versionType=commit&version={commitSha}&path=/*",
+                    "refs/heads/main",
                     s_relativeSourceLinkJsonPath,
                     $"https://test.{host}/test-org/_git/{repoName}",
                     $"https://test.{host}/test-org/_git/{repoName}",
@@ -100,6 +102,7 @@ public void FullValidation_Ssh(string host)
                 {
                     "@(SourceRoot)",
                     "@(SourceRoot->'%(SourceLinkUrl)')",
+                    "@(SourceRoot->'%(BranchName)')",
                     "$(SourceLink)",
                     "$(PrivateRepositoryUrl)",
                     "$(RepositoryUrl)"
@@ -109,6 +112,7 @@ public void FullValidation_Ssh(string host)
                     NuGetPackageFolders,
                     ProjectSourceRoot,
                     $"https://test.{host}/test-org/_apis/git/repositories/{repoName}/items?api-version=1.0&versionType=commit&version={commitSha}&path=/*",
+                    "refs/heads/main",
                     s_relativeSourceLinkJsonPath,
                     $"https://test.{host}/test-org/_git/{repoName}",
                     $"https://test.{host}/test-org/_git/{repoName}",