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//
// FileStreamRWLock_POSIX.h
//
// Library: Foundation
// Package: Processes
// Module: FileStreamRWLock
//
// Definition of the FileStreamRWLockImpl class for POSIX FileStream.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_FileStreamRWLock_POSIX_INCLUDED
#define Foundation_FileStreamRWLock_POSIX_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Exception.h"
#include "Poco/FileStream.h"
#include <fcntl.h>
#include <cerrno>
namespace Poco {
class Foundation_API FileStreamRWLockImpl
{
protected:
FileStreamRWLockImpl(const FileStream::NativeHandle &fd, Poco::UInt64 offset, Poco::UInt64 size);
~FileStreamRWLockImpl();
void readLockImpl();
bool tryReadLockImpl();
void writeLockImpl();
bool tryWriteLockImpl();
void unlockImpl();
private:
FileStream::NativeHandle _fd;
struct flock _flock;
int _lockMode;
};
//
// inlines
//
inline void FileStreamRWLockImpl::readLockImpl()
{
_flock.l_type = F_RDLCK;
_lockMode = F_SETLKW;
int rc = fcntl(_fd, _lockMode, &_flock);
if (rc == -1)
throw SystemException("cannot lock reader lock", errno);
}
inline bool FileStreamRWLockImpl::tryReadLockImpl()
{
_flock.l_type = F_RDLCK;
_lockMode = F_SETLK;
int rc = fcntl(_fd, _lockMode, &_flock);
if (rc == 0)
return true;
else if (errno == EAGAIN || errno == EACCES)
return false;
else
throw SystemException("cannot lock try-reader lock", errno);
}
inline void FileStreamRWLockImpl::writeLockImpl()
{
_flock.l_type = F_WRLCK;
_lockMode = F_SETLKW;
int rc = fcntl(_fd, _lockMode, &_flock);
if (rc == -1)
throw SystemException("cannot lock writer lock", errno);
}
inline bool FileStreamRWLockImpl::tryWriteLockImpl()
{
_flock.l_type = F_WRLCK;
_lockMode = F_SETLK;
int rc = fcntl(_fd, _lockMode, &_flock);
if (rc != -1)
return true;
else if (errno == EAGAIN || errno == EACCES)
return false;
else
throw SystemException("cannot lock writer lock", errno);
}
inline void FileStreamRWLockImpl::unlockImpl()
{
_flock.l_type = F_UNLCK;
_lockMode = F_SETLKW;
int rc = fcntl(_fd, _lockMode, &_flock);
if (rc == -1)
throw SystemException("cannot unlock", errno);
}
} // namespace Poco
#endif // Foundation_FileStreamRWLock_POSIX_INCLUDED
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