Add Repository.Discover() method

Given a path, this method will probe for a valid git repository, either bare or standard.

Should fix issue #25.

3 files changed, 59 insertions, 1 deletions

diff --git a/LibGit2Sharp.Tests/RepositoryFixture.cs b/LibGit2Sharp.Tests/RepositoryFixture.cs
index 4c137b73..06146a06 100644
--- a/LibGit2Sharp.Tests/RepositoryFixture.cs
+++ b/LibGit2Sharp.Tests/RepositoryFixture.cs
@@ -250,5 +250,40 @@ namespace LibGit2Sharp.Tests
                 Assert.Throws<ArgumentNullException>(() => repo.HasObject(null));
             }
         }
+
+        [Test]
+        public void CanDiscoverABareRepoGivenTheRepoPath()
+        {
+            string path = Repository.Discover(Constants.TestRepoPath);
+            path.ShouldEqual(Path.GetFullPath(Constants.TestRepoPath));
+        }
+
+        [Test]
+        public void CanDiscoverABareRepoGivenASubDirectoryOfTheRepoPath()
+        {
+            string path = Repository.Discover(Path.Combine(Constants.TestRepoPath, "objects/4a"));
+            path.ShouldEqual(Path.GetFullPath(Constants.TestRepoPath));
+        }
+
+        [Test]
+        public void CanDiscoverAStandardRepoGivenTheRepoPath()
+        {
+            string path = Repository.Discover(Constants.TestRepoWithWorkingDirPath);
+            path.ShouldEqual(Path.GetFullPath(Constants.TestRepoWithWorkingDirPath));
+        }
+
+        [Test]
+        public void CanDiscoverAStandardRepoGivenASubDirectoryOfTheRepoPath()
+        {
+            string path = Repository.Discover(Path.Combine(Constants.TestRepoWithWorkingDirPath, "objects/4a"));
+            path.ShouldEqual(Path.GetFullPath(Constants.TestRepoWithWorkingDirPath));
+        }
+
+        [Test]
+        public void CanDiscoverAStandardRepoGivenTheWorkingDirPath()
+        {
+            string path = Repository.Discover(Constants.TestRepoWithWorkingDirRootPath);
+            path.ShouldEqual(Path.GetFullPath(Constants.TestRepoWithWorkingDirPath));
+        }
     }
 }
\ No newline at end of file
diff --git a/LibGit2Sharp/Core/NativeMethods.cs b/LibGit2Sharp/Core/NativeMethods.cs
index b000458c..10b2594a 100644
--- a/LibGit2Sharp/Core/NativeMethods.cs
+++ b/LibGit2Sharp/Core/NativeMethods.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Text;
 
 namespace LibGit2Sharp.Core
 {
@@ -144,6 +145,11 @@ namespace LibGit2Sharp.Core
         public static extern IntPtr git_repository_database(RepositorySafeHandle repository);
 
         [DllImport(libgit2)]
+        public static extern int git_repository_discover(StringBuilder repository_path, int size, string start_path,
+                                                         [MarshalAs(UnmanagedType.Bool)] bool across_fs,
+                                                         string ceiling_dirs);
+        
+        [DllImport(libgit2)]
         public static extern void git_repository_free(IntPtr repository);
 
         [DllImport(libgit2)]
diff --git a/LibGit2Sharp/Repository.cs b/LibGit2Sharp/Repository.cs
index 4f60318c..bc3a4bf1 100644
--- a/LibGit2Sharp/Repository.cs
+++ b/LibGit2Sharp/Repository.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Text;
 using LibGit2Sharp.Core;
 
 namespace LibGit2Sharp
@@ -153,7 +154,7 @@ namespace LibGit2Sharp
         /// </summary>
         /// <param name = "sha">The sha.</param>
         /// <returns></returns>
-        public bool HasObject(string sha)
+        public bool HasObject(string sha)   //TODO: To be removed from front facing API (maybe should we create an Repository.Advanced to hold those kind of functions)?
         {
             Ensure.ArgumentNotNullOrEmptyString(sha, "sha");
 
@@ -235,5 +236,21 @@ namespace LibGit2Sharp
         {
             return reference != null && ((reference is DirectReference) || (reference is SymbolicReference && ((SymbolicReference)reference).Target != null));
         }
+
+        /// <summary>
+        /// Probe for a git repository.
+        /// <para>The lookup start from <paramref name="startingPath"/> and walk upward parent directories if nothing has been found.</para> 
+        /// </summary>
+        /// <param name="startingPath">The base path where the lookup starts.</param>
+        /// <returns>The path to the git repository.</returns>
+        public static string Discover(string startingPath)
+        {
+            var buffer = new StringBuilder(4096);
+
+            int result = NativeMethods.git_repository_discover(buffer, buffer.Capacity, PosixPathHelper.ToPosix(startingPath), false, null);
+            Ensure.Success(result);
+
+            return PosixPathHelper.ToNative(buffer.ToString());
+        }
     }
 }
\ No newline at end of file