Fix recursive filesystem enumeration

The default GetFiles recursive method on Mono goes into an infinite loop
when encountering symlinks that point to ./.

Switch to yield for recursive filesystem enumeration so we can abort early

Look for custom git-lfs executables in the same directory as git before looking
recursively from the git installation path, as that can take a really long
time and chances are git-lfs is right there in the same dir.

Author: shana

src/GitHub.Api/IO/FileSystem.cs

@@ -143,9 +143,10 @@ public string GetFileNameWithoutExtension(string fileName)
             return Path.GetFileNameWithoutExtension(fileName);
         }
 
+
         public IEnumerable<string> GetFiles(string path)
         {
-            return Directory.GetFiles(path);
+            return GetFiles(path, "*");
         }
 
         public IEnumerable<string> GetFiles(string path, string pattern)
@@ -155,7 +156,43 @@ public IEnumerable<string> GetFiles(string path, string pattern)
 
         public IEnumerable<string> GetFiles(string path, string pattern, SearchOption searchOption)
         {
-            return Directory.GetFiles(path, pattern, searchOption);
+            foreach (var file in GetFiles(path, pattern))
+                yield return file;
+
+            if (searchOption != SearchOption.AllDirectories)
+                yield break;
+
+#if ENABLE_MONO
+            if (NPath.IsLinux)
+            {
+                try
+                {
+                    path = Mono.Unix.UnixPath.GetCompleteRealPath(path);
+                }
+                catch
+                {}
+            }
+#endif
+            foreach (var dir in GetDirectories(path))
+            {
+                var realdir = dir;
+#if ENABLE_MONO
+                if (NPath.IsLinux)
+                {
+                    try
+                    {
+                        realdir = Mono.Unix.UnixPath.GetCompleteRealPath(dir);
+                    }
+                    catch
+                    {}
+                }
+#endif
+                if (path != realdir)
+                {
+                    foreach (var file in GetFiles(dir, pattern, searchOption))
+                        yield return file;
+                }
+            }
         }
 
         public byte[] ReadAllBytes(string path)

src/GitHub.Api/Installer/GitInstaller.cs

@@ -67,9 +67,13 @@ public GitInstallationState VerifyGitSettings(GitInstallationState state = null)
             if (state.GitIsValid)
                 state.GitInstallationPath = state.GitExecutablePath.Parent.Parent;
 
-            var isDefaultGitLfs = !state.GitLfsExecutablePath.IsInitialized || state.GitLfsInstallationPath == state.GitInstallationPath;
+            var isDefaultGitLfs = !state.GitLfsExecutablePath.IsInitialized;
             if (isDefaultGitLfs)
-                state.GitLfsExecutablePath = ProcessManager.FindExecutableInPath(installDetails.GitLfsExecutable, true, state.GitInstallationPath);
+            {
+                state.GitLfsExecutablePath = ProcessManager.FindExecutableInPath(installDetails.GitLfsExecutable, false, state.GitExecutablePath.Parent);
+                if (!state.GitLfsExecutablePath.IsInitialized)
+                    state.GitLfsExecutablePath = ProcessManager.FindExecutableInPath(installDetails.GitLfsExecutable, true, state.GitInstallationPath);
+            }
 
             state = ValidateGitLfsVersion(state);