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/*
* Copyright (C) 2010, T-Mobile USA, Inc.
*
* 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 __LIBS_FILE_LOCK_H
#define __LIBS_FILE_LOCK_H
#include <fcntl.h>
namespace android {
/*
* Object oriented interface for flock. Implements reference counting so that
* multiple levels of locks on the same object instance is possible.
*/
class FileLock {
public:
FileLock(const char* fileName);
/*
* Lock the file. A balanced call to unlock is required even if the lock
* fails.
*/
bool lock(int openFlags=O_RDWR, mode_t fileCreateMode=0755) {
mRefCount++;
if (mFd == -1) {
return doLock(openFlags, fileCreateMode);
} else {
return true;
}
}
/*
* Call this when mapping is no longer needed.
*/
void unlock(void) {
if (--mRefCount <= 0) {
delete this;
}
}
/*
* Return the name of the file this map came from, if known.
*/
const char* getFileName(void) const { return mFileName; }
/*
* Return the open file descriptor, if locked; -1 otherwise.
*/
int getFileDescriptor(void) const { return mFd; }
protected:
// don't delete objects; call unlock()
~FileLock(void);
bool doLock(int openFlags, mode_t fileCreateMode);
private:
int mRefCount; // reference count
int mFd; // file descriptor, if locked
char* mFileName; // original file name, if known
};
}; // namespace android
#endif // __LIBS_FILE_LOCK_H
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