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/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file LICENSE.rst or https://cmake.org/licensing for details. */
#pragma once
#include "cmConfigure.h" // IWYU pragma: keep
#include <string>
#if defined(_WIN32)
# include <memory>
using HANDLE = void*;
#endif
class cmFileLockResult;
/**
* @brief Cross-platform file locking.
* @details Under the hood this class use 'fcntl' for Unix-like platforms and
* 'LockFileEx'/'UnlockFileEx' for Win32 platform. Locks are exclusive and
* advisory.
*/
class cmFileLock
{
public:
cmFileLock();
~cmFileLock();
cmFileLock(cmFileLock const&) = delete;
cmFileLock(cmFileLock&&) noexcept;
cmFileLock& operator=(cmFileLock const&) = delete;
cmFileLock& operator=(cmFileLock&&) noexcept;
/**
* @brief Lock the file.
* @param timeoutSec Lock timeout. If -1 try until success or fatal error.
*/
cmFileLockResult Lock(std::string const& filename, unsigned long timeoutSec);
/**
* @brief Unlock the file.
*/
cmFileLockResult Release();
/**
* @brief Check file is locked by this class.
* @details This function helps to find double locks (deadlocks) and to do
* explicit unlocks.
*/
bool IsLocked(std::string const& filename) const;
private:
cmFileLockResult OpenFile();
cmFileLockResult LockWithoutTimeout();
cmFileLockResult LockWithTimeout(unsigned long timeoutSec);
#if defined(_WIN32)
HANDLE File = (HANDLE)-1;
std::unique_ptr<struct _OVERLAPPED> Overlapped;
int LockFile(int flags);
#else
int File = -1;
int LockFile(int cmd, int type) const;
#endif
std::string Filename;
};
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