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      1 /*
      2  * Copyright 2012, The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef BCC_SUPPORT_FILE_H
     18 #define BCC_SUPPORT_FILE_H
     19 
     20 #include "bcc/Support/FileBase.h"
     21 
     22 namespace bcc {
     23 
     24 template<enum FileBase::OpenModeEnum OpenMode>
     25 struct FileAttribute {
     26   // The flags to the 2nd argument in ::open().
     27   enum { kOpenFlags };
     28 
     29   // Default value of LockMode.
     30   enum { kDefaultLockMode };
     31 };
     32 
     33 // FileAttribute for accessing read-only file
     34 template<>
     35 struct FileAttribute<FileBase::kReadMode> {
     36   enum { kOpenFlags       = O_RDONLY };
     37   enum { kDefaultLockMode = FileBase::kReadLock };
     38 };
     39 
     40 // FileAttribute for accessing writable file
     41 template<>
     42 struct FileAttribute<FileBase::kWriteMode> {
     43   enum { kOpenFlags       = O_RDWR | O_CREAT };
     44   enum { kDefaultLockMode = FileBase::kWriteLock };
     45 };
     46 
     47 template<enum FileBase::OpenModeEnum OpenMode>
     48 class File : public FileBase {
     49 public:
     50   File(const std::string &pFilename, unsigned pFlags)
     51     : FileBase(pFilename, FileAttribute<OpenMode>::kOpenFlags, pFlags) { }
     52 
     53   inline bool lock(enum LockModeEnum pMode = static_cast<enum LockModeEnum>(
     54                       FileAttribute<OpenMode>::kDefaultLockMode),
     55                    bool pNonblocking = true,
     56                    unsigned pMaxRetry = FileBase::kDefaultMaxRetryLock,
     57                    useconds_t pRetryInterval =
     58                       FileBase::kDefaultRetryLockInterval) {
     59     return FileBase::lock(pMode, pNonblocking, pMaxRetry, pRetryInterval);
     60   }
     61 
     62   inline android::FileMap *createMap(off_t pOffset, size_t pLength,
     63                                      bool pIsReadOnly =
     64                                         (OpenMode == FileBase::kReadMode)) {
     65     return FileBase::createMap(pOffset, pLength, pIsReadOnly);
     66   }
     67 };
     68 
     69 
     70 } // end namespace bcc
     71 
     72 #endif  // BCC_SUPPORT_FILE_H
     73