Source/cmFileLockWin32.cxx

/*============================================================================
  CMake - Cross Platform Makefile Generator
  Copyright 2014 Ruslan Baratov

  Distributed under the OSI-approved BSD License (the "License");
  see accompanying file Copyright.txt for details.

  This software is distributed WITHOUT ANY WARRANTY; without even the
  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the License for more information.
============================================================================*/

#include "cmFileLock.h"

#include "cmSystemTools.h"
#include <windows.h> // CreateFileW

cmFileLock::cmFileLock()
  : File(INVALID_HANDLE_VALUE)
{
}

cmFileLockResult cmFileLock::Release()
{
  if (this->Filename.empty()) {
    return cmFileLockResult::MakeOk();
  }
  const unsigned long len = static_cast<unsigned long>(-1);
  static OVERLAPPED overlapped;
  const DWORD reserved = 0;
  const BOOL unlockResult =
    UnlockFileEx(File, reserved, len, len, &overlapped);

  this->Filename = "";

  CloseHandle(this->File);
  this->File = INVALID_HANDLE_VALUE;

  if (unlockResult) {
    return cmFileLockResult::MakeOk();
  } else {
    return cmFileLockResult::MakeSystem();
  }
}

cmFileLockResult cmFileLock::OpenFile()
{
  const DWORD access = GENERIC_READ | GENERIC_WRITE;
  const DWORD shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
  const PSECURITY_ATTRIBUTES security = NULL;
  const DWORD attr = 0;
  const HANDLE templ = NULL;
  this->File = CreateFileW(
    cmSystemTools::ConvertToWindowsExtendedPath(this->Filename).c_str(),
    access, shareMode, security, OPEN_EXISTING, attr, templ);
  if (this->File == INVALID_HANDLE_VALUE) {
    return cmFileLockResult::MakeSystem();
  } else {
    return cmFileLockResult::MakeOk();
  }
}

cmFileLockResult cmFileLock::LockWithoutTimeout()
{
  if (!this->LockFile(LOCKFILE_EXCLUSIVE_LOCK)) {
    return cmFileLockResult::MakeSystem();
  } else {
    return cmFileLockResult::MakeOk();
  }
}

cmFileLockResult cmFileLock::LockWithTimeout(unsigned long seconds)
{
  const DWORD flags = LOCKFILE_EXCLUSIVE_LOCK | LOCKFILE_FAIL_IMMEDIATELY;
  while (true) {
    const BOOL result = this->LockFile(flags);
    if (result) {
      return cmFileLockResult::MakeOk();
    }
    const DWORD error = GetLastError();
    if (error != ERROR_LOCK_VIOLATION) {
      return cmFileLockResult::MakeSystem();
    }
    if (seconds == 0) {
      return cmFileLockResult::MakeTimeout();
    }
    --seconds;
    cmSystemTools::Delay(1000);
  }
}

BOOL cmFileLock::LockFile(DWORD flags)
{
  const DWORD reserved = 0;
  const unsigned long len = static_cast<unsigned long>(-1);
  static OVERLAPPED overlapped;
  return LockFileEx(this->File, flags, reserved, len, len, &overlapped);
}