Handle tags that do not have a tagger.

LibGit2Sharp.Tests/ReferenceFixture.cs

@@ -13,7 +13,7 @@ public class ReferenceFixture : BaseFixture
                                                      {
                                                          "refs/heads/br2", "refs/heads/deadbeef", "refs/heads/master", "refs/heads/packed", "refs/heads/packed-test",
                                                          "refs/heads/test", "refs/notes/answer", "refs/notes/answer2", "refs/notes/commits", "refs/tags/e90810b",
-                                                         "refs/tags/lw", "refs/tags/point_to_blob", "refs/tags/test"
+                                                         "refs/tags/lw", "refs/tags/point_to_blob", "refs/tags/tag_without_tagger", "refs/tags/test"
                                                      };
 
         [Fact]
@@ -320,7 +320,7 @@ public void CanListAllReferencesEvenCorruptedOnes()
 
                 Assert.Equal(expectedRefs, SortedRefs(repo, r => r.CanonicalName));
 
-                Assert.Equal(13, repo.Refs.Count());
+                Assert.Equal(14, repo.Refs.Count());
             }
         }
 
@@ -730,9 +730,9 @@ public void CanFilterReferencesWithAGlob()
         {
             using (var repo = new Repository(BareTestRepoPath))
             {
-                Assert.Equal(12, repo.Refs.FromGlob("*").Count());
+                Assert.Equal(13, repo.Refs.FromGlob("*").Count());
                 Assert.Equal(5, repo.Refs.FromGlob("refs/heads/*").Count());
-                Assert.Equal(4, repo.Refs.FromGlob("refs/tags/*").Count());
+                Assert.Equal(5, repo.Refs.FromGlob("refs/tags/*").Count());
                 Assert.Equal(3, repo.Refs.FromGlob("*t?[pqrs]t*").Count());
                 Assert.Equal(0, repo.Refs.FromGlob("test").Count());
             }

LibGit2Sharp.Tests/Resources/testrepo.git/objects/25/2846a95d7b031136d19f5a8a85ebed204cdbef

@@ -0,0 +1,2 @@
+x
��� D=SŖ ?�j�.�A��1v/&��&�	�h����,i���੕Rr�z�H�葔Ӌw����|!
+n-�[8ׇ��	/!8����G�����$

LibGit2Sharp.Tests/Resources/testrepo.git/refs/tags/tag_without_tagger

@@ -0,0 +1 @@
+252846a95d7b031136d19f5a8a85ebed204cdbef

LibGit2Sharp.Tests/TagFixture.cs

@@ -9,7 +9,7 @@ namespace LibGit2Sharp.Tests
 {
     public class TagFixture : BaseFixture
     {
-        private readonly string[] expectedTags = new[] { "e90810b", "lw", "point_to_blob", "test", };
+        private readonly string[] expectedTags = new[] { "e90810b", "lw", "point_to_blob", "tag_without_tagger", "test", };
 
         private static readonly Signature signatureTim = new Signature("Tim Clem", "timothy.clem@gmail.com", TruncateSubSeconds(DateTimeOffset.UtcNow));
         private static readonly Signature signatureNtk = new Signature("nulltoken", "emeric.fermas@gmail.com", Epoch.ToDateTimeOffset(1300557894, 60));
@@ -350,6 +350,25 @@ public void CanAddATagPointingToATree()
             }
         }
 
+        [Fact]
+        public void CanReadTagWithoutTagger()
+        {
+            // Not all tags have a tagger.
+            using (var repo = new Repository(BareTestRepoPath))
+            {
+                Tag tag = repo.Tags["tag_without_tagger"];
+
+                Assert.True(tag.IsAnnotated);
+                Assert.NotNull(tag.Target);
+                Assert.Null(tag.Annotation.Tagger);
+
+                Tree tree = repo.Lookup<Tree>("581f9824ecaf824221bd36edf5430f2739a7c4f5");
+                Assert.NotNull(tree);
+
+                Assert.Equal(tree.Id, tag.Target.Id);
+            }
+        }
+
         [Fact]
         public void CanAddATagPointingToABlob()
         {
@@ -590,7 +609,7 @@ public void CanListTags()
             {
                 Assert.Equal(expectedTags, SortedTags(repo.Tags, t => t.Name));
 
-                Assert.Equal(4, repo.Tags.Count());
+                Assert.Equal(5, repo.Tags.Count());
             }
         }
 

LibGit2Sharp/Core/Proxy.cs

@@ -2885,7 +2885,17 @@ public static string git_tag_name(GitObjectSafeHandle tag)
 
         public static Signature git_tag_tagger(GitObjectSafeHandle tag)
         {
-            return new Signature(NativeMethods.git_tag_tagger(tag));
+            IntPtr taggerHandle = NativeMethods.git_tag_tagger(tag);
+
+            // Not all tags have a tagger signature - we need to handle
+            // this case.
+            Signature tagger = null;
+            if (taggerHandle != IntPtr.Zero)
+            {
+                tagger = new Signature(NativeMethods.git_tag_tagger(tag));
+            }
+
+            return tagger;
         }
 
         public static ObjectId git_tag_target_id(GitObjectSafeHandle tag)