[Chromecast] Remove usage of nonreentrant functions.

chromecast/base/file_utils.cc

Index: chromecast/base/file_utils.cc
diff --git a/chromecast/base/file_utils.cc b/chromecast/base/file_utils.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6a278a7ad8ebec51f587ba2e1b00edabfd1aa688
--- /dev/null
+++ b/chromecast/base/file_utils.cc
@@ -0,0 +1,40 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chromecast/base/file_utils.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/file.h>
+
+namespace {
+
+bool AttemptLockOnFileWithFlag(const base::FilePath& path, int flag) {
+  int fd, ret;
+  const char* file = path.value().c_str();
+
+  if ((fd = open(file, O_RDONLY)) < 0) {
+    LOG(ERROR) << "Error opening " << file << " error = " << strerror(errno);
+    return false;
+  }
+  if ((ret = TEMP_FAILURE_RETRY(flock(fd, flag))) < 0)
+    LOG(ERROR) << "Error locking " << file << " error = " << strerror(errno);
+
+  close(fd);
+  return !ret;
+}
+
+}  // namespace
+
+namespace chromecast {
+
+bool LockFile(const base::FilePath& path) {
+  return AttemptLockOnFileWithFlag(path, LOCK_EX);
+}
+
+bool UnlockFile(const base::FilePath& path) {
+  return AttemptLockOnFileWithFlag(path, LOCK_UN);
+}
+
+}  // namspace chromecast