Add FileDescriptor class

A simple class to wrap a file descriptor so it can
be opened on construction and closed on destruction.

Change-Id: I16d481fdc91e99720acd9cabff3a3a4690d8a573
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/filedescriptor.cpp b/filedescriptor.cpp
new file mode 100644
index 0000000..3b1b096
--- /dev/null
+++ b/filedescriptor.cpp
@@ -0,0 +1,49 @@
+/**
+ * Copyright © 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <stdexcept>
+#include <unistd.h>
+#include "filedescriptor.hpp"
+
+namespace openpower
+{
+namespace p9_util
+{
+
+FileDescriptor::FileDescriptor(const std::string& path)
+{
+    fd = open(path.c_str(), O_RDWR | O_SYNC);
+
+    if (fd < 0)
+    {
+        //Future: use a different exception to create an error log
+        char msg[200];
+        sprintf(msg, "Failed to open FSI device path %s.  errno = %d",
+                path.c_str(), errno);
+        throw std::runtime_error(msg);
+    }
+}
+
+
+FileDescriptor::~FileDescriptor()
+{
+    if (fd >= 0)
+    {
+        close(fd);
+    }
+}
+
+}
+}