Add file access overload to RootStorage.Open

Author: jeremy-visionaid

OpenMcdf.Tests/RootStorageTests.cs

@@ -12,6 +12,7 @@ public void Open(string fileName)
         using var rootStorage2 = RootStorage.OpenRead(fileName);
 
         Assert.ThrowsException<IOException>(() => RootStorage.Open(fileName, FileMode.Open));
+        Assert.ThrowsException<IOException>(() => RootStorage.Open(fileName, FileMode.Open, FileAccess.ReadWrite));
         Assert.ThrowsException<IOException>(() => RootStorage.OpenWrite(fileName));
     }
 

OpenMcdf/RootStorage.cs

@@ -70,6 +70,14 @@ public static RootStorage Open(string fileName, FileMode mode, StorageModeFlags
         return Open(stream, flags);
     }
 
+    public static RootStorage Open(string fileName, FileMode mode, FileAccess access, StorageModeFlags flags = StorageModeFlags.None)
+    {
+        ThrowIfLeaveOpen(flags);
+
+        FileStream stream = File.Open(fileName, mode, access);
+        return Open(stream, flags);
+    }
+
     public static RootStorage Open(Stream stream, StorageModeFlags flags = StorageModeFlags.None)
     {
         stream.ThrowIfNotSeekable();