refactor<*>: rewrite all codes...

src/Commands/QueryGitDir.cs

@@ -0,0 +1,23 @@
+using System.IO;
+
+namespace SourceGit.Commands {
+
+    /// <summary>
+    ///     取得GitDir
+    /// </summary>
+    public class QueryGitDir : Command {
+        public QueryGitDir(string workDir) {
+            Cwd = workDir;
+            Args = "rev-parse --git-dir";
+        }
+
+        public string Result() {
+            var rs = ReadToEnd().Output;
+            if (string.IsNullOrEmpty(rs)) return null;
+
+            rs = rs.Trim();
+            if (Path.IsPathRooted(rs)) return rs;
+            return Path.Combine(Cwd, rs);
+        }
+    }
+}