versioner: introduce.

Add a clang-based tool to inspect header availability attributes and
verify them against the NDK platform definitions.

Bug: http://b/28178111
Change-Id: I1bb1925a620e98cc9606cb5a3360b1224c700bd0
diff --git a/tools/versioner/src/Utils.cpp b/tools/versioner/src/Utils.cpp
new file mode 100644
index 0000000..92cc9de
--- /dev/null
+++ b/tools/versioner/src/Utils.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2016 The Android Open Source Project
+ *
+ * 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 "Utils.h"
+
+#include <err.h>
+#include <fts.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+std::string getWorkingDir() {
+  char buf[PATH_MAX];
+  if (!getcwd(buf, sizeof(buf))) {
+    err(1, "getcwd failed");
+  }
+  return buf;
+}
+
+std::vector<std::string> collectFiles(const std::string& directory) {
+  std::vector<std::string> files;
+
+  char* dir_argv[2] = { const_cast<char*>(directory.c_str()), nullptr };
+  FTS* fts = fts_open(dir_argv, FTS_LOGICAL | FTS_NOCHDIR, nullptr);
+
+  if (!fts) {
+    err(1, "failed to open directory '%s'", directory.c_str());
+  }
+
+  FTSENT* ent;
+  while ((ent = fts_read(fts))) {
+    if (ent->fts_info & (FTS_D | FTS_DP)) {
+      continue;
+    }
+
+    files.push_back(ent->fts_path);
+  }
+
+  fts_close(fts);
+  return files;
+}