cmFileLock.h 1.51 KB
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/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   file Copyright.txt or https://cmake.org/licensing for details.  */
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#ifndef cmFileLock_h
#define cmFileLock_h

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#include <cmConfigure.h> // IWYU pragma: keep
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#include <string>
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#if defined(_WIN32)
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#include <windows.h> // HANDLE
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#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
{
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public:
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  cmFileLock();
  ~cmFileLock();

  /**
    * @brief Lock the file.
    * @param timeoutSec Lock timeout. If -1 try until success or fatal error.
    */
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  cmFileLockResult Lock(const std::string& filename, unsigned long timeoutSec);
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  /**
    * @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(const std::string& filename) const;

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private:
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  cmFileLock(const cmFileLock&);
  cmFileLock& operator=(const cmFileLock&);

  cmFileLockResult OpenFile();
  cmFileLockResult LockWithoutTimeout();
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  cmFileLockResult LockWithTimeout(unsigned long timeoutSec);
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#if defined(_WIN32)
  typedef HANDLE FileId;
  BOOL LockFile(DWORD flags);
#else
  typedef int FileId;
  int LockFile(int cmd, int type);
#endif

  FileId File;
  std::string Filename;
};

#endif // cmFileLock_h