Port Android relocation packer to chromium build

third_party/android_platform/relocation_packer/src/nativehelper/ScopedFd.h

+/*
+ * Copyright (C) 2009 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.
+ */
+
+#ifndef SCOPED_FD_H_included
+#define SCOPED_FD_H_included
+
+#include <unistd.h>
+
+// Local definition of DISALLOW_COPY_AND_ASSIGN, avoids depending on base.
+#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
+  TypeName(const TypeName&);               \
+  void operator=(const TypeName&)
+
+// A smart pointer that closes the given fd on going out of scope.
+// Use this when the fd is incidental to the purpose of your function,
+// but needs to be cleaned up on exit.
+class ScopedFd {
+public:
+    explicit ScopedFd(int fd) : fd_(fd) {
+    }
+
+    ~ScopedFd() {
+      reset();
+    }
+
+    int get() const {
+        return fd_;
+    }
+
+    int release() __attribute__((warn_unused_result)) {
+        int localFd = fd_;
+        fd_ = -1;
+        return localFd;
+    }
+
+    void reset(int new_fd = -1) {
+      if (fd_ != -1) {
+          TEMP_FAILURE_RETRY(close(fd_));
+      }
+      fd_ = new_fd;
+    }
+
+private:
+    int fd_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedFd);
+};
+
+#endif  // SCOPED_FD_H_included