bmc: implement search for json files

Tested: Verified it prints out the blobs expected.
Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I1ba6af8b2ca066e6eb1699cb4214ce32f148005d
diff --git a/bmc/fs.cpp b/bmc/fs.cpp
new file mode 100644
index 0000000..c43e310
--- /dev/null
+++ b/bmc/fs.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * 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 "fs.hpp"
+
+#include <filesystem>
+#include <regex>
+#include <string>
+#include <vector>
+
+namespace ipmi_flash
+{
+namespace fs = std::filesystem;
+
+std::vector<std::string> GetJsonList(const std::string& directory)
+{
+    std::vector<std::string> output;
+
+    for (const auto& p : fs::recursive_directory_iterator(directory))
+    {
+        auto ps = p.path().string();
+
+        /** TODO: openbmc/phosphor-ipmi-blobs/blob/de8a16e2e8/fs.cpp#L27 is
+         * nicer, may be worth finding a way to make this into a util.
+         */
+        if (std::regex_match(ps, std::regex(".+.json$")))
+        {
+            output.push_back(ps);
+        }
+    }
+
+    return output;
+}
+
+} // namespace ipmi_flash