(GH-943) IFileSystem - Open File Exclusively

Add method for opening a file exclusively.

src/chocolatey/infrastructure/filesystem/DotNetFileSystem.cs

@@ -382,6 +382,11 @@ public FileStream open_file_readonly(string filePath)
             return File.OpenRead(filePath);
         }
 
+        public FileStream open_file_exclusive(string filePath)
+        {
+            return File.Open(filePath,FileMode.OpenOrCreate,FileAccess.ReadWrite,FileShare.None);
+        }
+
         public void write_file(string filePath, string fileText)
         {
             write_file(filePath, fileText, file_exists(filePath) ? get_file_encoding(filePath) : Encoding.UTF8);

src/chocolatey/infrastructure/filesystem/IFileSystem.cs

@@ -238,6 +238,13 @@ public interface IFileSystem
         /// <returns>A file stream object for use after accessing the file</returns>
         FileStream open_file_readonly(string filePath);
 
+        /// <summary>
+        ///   Opens a file exlusively
+        /// </summary>
+        /// <param name="filePath">Path to the file name</param>
+        /// <returns>A file stream object for use after accessing the file</returns>
+        FileStream open_file_exclusive(string filePath);
+
         /// <summary>
         ///   Writes the file text to the specified path
         /// </summary>