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      1 // Copyright 2014 The Android Open Source Project
      2 //
      3 // This software is licensed under the terms of the GNU General Public
      4 // License version 2, as published by the Free Software Foundation, and
      5 // may be copied, distributed, and modified under those terms.
      6 //
      7 // This program is distributed in the hope that it will be useful,
      8 // but WITHOUT ANY WARRANTY; without even the implied warranty of
      9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     10 // GNU General Public License for more details.
     11 
     12 #ifndef ANDROID_BASE_FILES_SCOPED_HANDLE_H
     13 #define ANDROID_BASE_FILES_SCOPED_HANDLE_H
     14 
     15 #if !defined(_WIN32) && !defined(_WIN64)
     16 #error "Only compile this file when targetting Windows!"
     17 #endif
     18 
     19 #include "android/base/Compiler.h"
     20 
     21 #define WIN32_LEAN_AND_MEAN 1
     22 #include <windows.h>
     23 
     24 namespace android {
     25 namespace base {
     26 
     27 // Helper class used to wrap a Win32 HANDLE that will be closed when
     28 // the instance is destroyed, unless the release() method was called
     29 // before that.
     30 class ScopedHandle {
     31 public:
     32     // Default destructor is used to wrap an invalid handle value.
     33     ScopedHandle() : handle_(INVALID_HANDLE_VALUE) {}
     34 
     35     // Constructor takes ownership of |handle|.
     36     explicit ScopedHandle(HANDLE handle) : handle_(handle) {}
     37 
     38     // Destructor calls close() method.
     39     ~ScopedHandle() { close(); }
     40 
     41     // Returns true iff the wrapped HANDLE value is valid.
     42     bool valid() const { return handle_ != INVALID_HANDLE_VALUE; }
     43 
     44     // Return current HANDLE value. Does _not_ transfer ownership.
     45     HANDLE get() const { return handle_; }
     46 
     47     // Return current HANDLE value, transferring ownership to the caller.
     48     HANDLE release() {
     49         HANDLE h = handle_;
     50         handle_ = INVALID_HANDLE_VALUE;
     51         return h;
     52     }
     53 
     54     // Close handle if it is not invalid.
     55     void close() {
     56         if (handle_ != INVALID_HANDLE_VALUE) {
     57             ::CloseHandle(handle_);
     58             handle_ = INVALID_HANDLE_VALUE;
     59         }
     60     }
     61 
     62     // Swap the content of two ScopedHandle instances.
     63     void swap(ScopedHandle* other) {
     64         HANDLE handle = handle_;
     65         handle_ = other->handle_;
     66         other->handle_ = handle;
     67     }
     68 
     69 private:
     70     DISALLOW_COPY_AND_ASSIGN(ScopedHandle);
     71 
     72     HANDLE handle_;
     73 };
     74 
     75 }  // namespace base
     76 }  // namespace android
     77 
     78 #endif  // ANDROID_BASE_FILES_SCOPED_HANDLE_H
     79