file: Add LOCK subcommand to do file and directory locking

Provide options to fail without blocking or to block up to a timeout.
Provide options to specify the scope containing the lock so it can be
released automatically at the end of a function, file, or process.

Extend the RunCMake.file test with cases covering the file(LOCK) command
usage and error cases.

14 files changed, 1110 insertions, 0 deletions

diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 7705683..a4c982f 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -219,6 +219,12 @@ set(SRCS
   cmExtraKateGenerator.h
   cmExtraSublimeTextGenerator.cxx
   cmExtraSublimeTextGenerator.h
+  cmFileLock.cxx
+  cmFileLock.h
+  cmFileLockPool.cxx
+  cmFileLockPool.h
+  cmFileLockResult.cxx
+  cmFileLockResult.h
   cmFileTimeComparison.cxx
   cmFileTimeComparison.h
   cmGeneratedFileStream.cxx
diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index aa4c95b..a6eb8c4 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -21,6 +21,7 @@
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cm_curl.h"
+#include "cmFileLockResult.h"
 #endif
 
 #undef GetCurrentDirectory
@@ -202,6 +203,10 @@ bool cmFileCommand
     {
     return this->HandleGenerateCommand(args);
     }
+  else if ( subCommand == "LOCK" )
+    {
+    return this->HandleLockCommand(args);
+    }
 
   std::string e = "does not recognize sub-command "+subCommand;
   this->SetError(e);
@@ -3502,6 +3507,204 @@ bool cmFileCommand::HandleGenerateCommand(
 }
 
 //----------------------------------------------------------------------------
+bool cmFileCommand::HandleLockCommand(
+  std::vector<std::string> const& args)
+{
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  // Default values
+  bool directory = false;
+  bool release = false;
+  enum Guard {
+    GUARD_FUNCTION,
+    GUARD_FILE,
+    GUARD_PROCESS
+  };
+  Guard guard = GUARD_PROCESS;
+  std::string resultVariable;
+  unsigned timeout = static_cast<unsigned>(-1);
+
+  // Parse arguments
+  if(args.size() < 2)
+    {
+    this->Makefile->IssueMessage(
+        cmake::FATAL_ERROR,
+        "sub-command LOCK requires at least two arguments.");
+    return false;
+    }
+
+  std::string path = args[1];
+  for (unsigned i = 2; i < args.size(); ++i)
+    {
+    if (args[i] == "DIRECTORY")
+      {
+      directory = true;
+      }
+    else if (args[i] == "RELEASE")
+      {
+      release = true;
+      }
+    else if (args[i] == "GUARD")
+      {
+      ++i;
+      const char* merr = "expected FUNCTION, FILE or PROCESS after GUARD";
+      if (i >= args.size())
+        {
+        this->Makefile->IssueMessage(cmake::FATAL_ERROR, merr);
+        return false;
+        }
+      else
+        {
+        if (args[i] == "FUNCTION")
+          {
+          guard = GUARD_FUNCTION;
+          }
+        else if (args[i] == "FILE")
+          {
+          guard = GUARD_FILE;
+          }
+        else if (args[i] == "PROCESS")
+          {
+          guard = GUARD_PROCESS;
+          }
+        else
+          {
+          cmOStringStream e;
+          e << merr << ", but got:\n  \"" << args[i] << "\".";
+          this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+          return false;
+          }
+        }
+      }
+    else if (args[i] == "RESULT_VARIABLE")
+      {
+      ++i;
+      if (i >= args.size())
+        {
+        this->Makefile->IssueMessage(
+            cmake::FATAL_ERROR,
+            "expected variable name after RESULT_VARIABLE");
+        return false;
+        }
+      resultVariable = args[i];
+      }
+    else if (args[i] == "TIMEOUT")
+      {
+      ++i;
+      if (i >= args.size())
+        {
+        this->Makefile->IssueMessage(
+            cmake::FATAL_ERROR,
+            "expected timeout value after TIMEOUT");
+        return false;
+        }
+      int scanned;
+      if(!cmSystemTools::StringToInt(args[i].c_str(), &scanned) || scanned < 0)
+        {
+        cmOStringStream e;
+        e << "TIMEOUT value \"" << args[i] << "\" is not an unsigned integer.";
+        this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+        return false;
+        }
+      timeout = static_cast<unsigned>(scanned);
+      }
+    else
+      {
+      cmOStringStream e;
+      e << "expected DIRECTORY, RELEASE, GUARD, RESULT_VARIABLE or TIMEOUT\n";
+      e << "but got: \"" << args[i] << "\".";
+      this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+      return false;
+      }
+    }
+
+  if (directory)
+    {
+    path += "/cmake.lock";
+    }
+
+  if (!cmsys::SystemTools::FileIsFullPath(path))
+    {
+    path = this->Makefile->GetCurrentDirectory() + ("/" + path);
+    }
+
+  // Unify path (remove '//', '/../', ...)
+  path = cmSystemTools::CollapseFullPath(path);
+
+  // Create file and directories if needed
+  std::string parentDir = cmSystemTools::GetParentDirectory(path);
+  if (!cmSystemTools::MakeDirectory(parentDir))
+    {
+    cmOStringStream e;
+    e << "directory\n  \"" << parentDir << "\"\ncreation failed ";
+    e << "(check permissions).";
+    this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+    cmSystemTools::SetFatalErrorOccured();
+    return false;
+    }
+  FILE *file = cmsys::SystemTools::Fopen(path, "w");
+  if (!file)
+    {
+    cmOStringStream e;
+    e << "file\n  \"" << path << "\"\ncreation failed (check permissions).";
+    this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+    cmSystemTools::SetFatalErrorOccured();
+    return false;
+    }
+  fclose(file);
+
+  // Actual lock/unlock
+  cmFileLockPool& lockPool = this->Makefile->GetLocalGenerator()->
+      GetGlobalGenerator()->GetFileLockPool();
+
+  cmFileLockResult fileLockResult(cmFileLockResult::MakeOk());
+  if (release)
+    {
+    fileLockResult = lockPool.Release(path);
+    }
+  else
+    {
+    switch (guard)
+      {
+      case GUARD_FUNCTION:
+        fileLockResult = lockPool.LockFunctionScope(path, timeout);
+        break;
+      case GUARD_FILE:
+        fileLockResult = lockPool.LockFileScope(path, timeout);
+        break;
+      case GUARD_PROCESS:
+        fileLockResult = lockPool.LockProcessScope(path, timeout);
+        break;
+      default:
+        cmSystemTools::SetFatalErrorOccured();
+        return false;
+      }
+    }
+
+  const std::string result = fileLockResult.GetOutputMessage();
+
+  if (resultVariable.empty() && !fileLockResult.IsOk())
+    {
+    cmOStringStream e;
+    e << "error locking file\n  \"" << path << "\"\n" << result << ".";
+    this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+    cmSystemTools::SetFatalErrorOccured();
+    return false;
+    }
+
+  if (!resultVariable.empty())
+    {
+    this->Makefile->AddDefinition(resultVariable, result.c_str());
+    }
+
+  return true;
+#else
+  static_cast<void>(args);
+  this->SetError("sub-command LOCK not implemented in bootstrap cmake");
+  return false;
+#endif
+}
+
+//----------------------------------------------------------------------------
 bool cmFileCommand::HandleTimestampCommand(
   std::vector<std::string> const& args)
 {
diff --git a/Source/cmFileCommand.h b/Source/cmFileCommand.h
index 8d66fdf..a4d341f 100644
--- a/Source/cmFileCommand.h
+++ b/Source/cmFileCommand.h
@@ -75,6 +75,7 @@ protected:
 
   bool HandleTimestampCommand(std::vector<std::string> const& args);
   bool HandleGenerateCommand(std::vector<std::string> const& args);
+  bool HandleLockCommand(std::vector<std::string> const& args);
 
 private:
   void AddEvaluationFile(const std::string &inputName,
diff --git a/Source/cmFileLock.cxx b/Source/cmFileLock.cxx
new file mode 100644
index 0000000..5f75637
--- /dev/null
+++ b/Source/cmFileLock.cxx
@@ -0,0 +1,78 @@
+/*============================================================================
+  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 <assert.h>
+#include "cmFileLockResult.h"
+
+// Common implementation
+
+cmFileLock::~cmFileLock()
+{
+  if (!this->Filename.empty())
+    {
+    const cmFileLockResult result = this->Release();
+    static_cast<void>(result);
+    assert(result.IsOk());
+    }
+}
+
+cmFileLockResult cmFileLock::Lock(
+    const std::string& filename, unsigned timeout)
+{
+  if (filename.empty())
+    {
+    // Error is internal since all the directories and file must be created
+    // before actual lock called.
+    return cmFileLockResult::MakeInternal();
+    }
+
+  if (!this->Filename.empty())
+    {
+    // Error is internal since double-lock must be checked in class
+    // cmFileLockPool by the cmFileLock::IsLocked method.
+    return cmFileLockResult::MakeInternal();
+    }
+
+  this->Filename = filename;
+  cmFileLockResult result = this->OpenFile();
+  if (result.IsOk())
+    {
+    if (timeout == static_cast<unsigned>(-1))
+      {
+      result = this->LockWithoutTimeout();
+      }
+    else
+      {
+      result = this->LockWithTimeout(timeout);
+      }
+    }
+
+  if (!result.IsOk())
+    {
+    this->Filename = "";
+    }
+
+  return result;
+}
+
+bool cmFileLock::IsLocked(const std::string& filename) const
+{
+  return filename == this->Filename;
+}
+
+#if defined(_WIN32)
+# include "cmFileLockWin32.cxx"
+#else
+# include "cmFileLockUnix.cxx"
+#endif
diff --git a/Source/cmFileLock.h b/Source/cmFileLock.h
new file mode 100644
index 0000000..4d922a0
--- /dev/null
+++ b/Source/cmFileLock.h
@@ -0,0 +1,74 @@
+/*============================================================================
+  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.
+============================================================================*/
+
+#ifndef cmFileLock_h
+#define cmFileLock_h
+
+#include "cmStandardIncludes.h"
+
+#if defined(_WIN32)
+# include <windows.h> // HANDLE
+#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();
+
+  /**
+    * @brief Lock the file.
+    * @param timeoutSec Lock timeout. If -1 try until success or fatal error.
+    */
+  cmFileLockResult Lock(const std::string& filename, unsigned 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(const std::string& filename) const;
+
+ private:
+  cmFileLock(const cmFileLock&);
+  cmFileLock& operator=(const cmFileLock&);
+
+  cmFileLockResult OpenFile();
+  cmFileLockResult LockWithoutTimeout();
+  cmFileLockResult LockWithTimeout(unsigned timeoutSec);
+
+#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
diff --git a/Source/cmFileLockPool.cxx b/Source/cmFileLockPool.cxx
new file mode 100644
index 0000000..e84e71a
--- /dev/null
+++ b/Source/cmFileLockPool.cxx
@@ -0,0 +1,198 @@
+/*============================================================================
+  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 "cmFileLockPool.h"
+
+#include <assert.h>
+
+#include "cmFileLock.h"
+#include "cmFileLockResult.h"
+
+cmFileLockPool::cmFileLockPool()
+{
+}
+
+cmFileLockPool::~cmFileLockPool()
+{
+  for (It i = this->FunctionScopes.begin();
+      i != this->FunctionScopes.end(); ++i)
+    {
+    delete *i;
+    }
+
+  for (It i = this->FileScopes.begin(); i != this->FileScopes.end(); ++i)
+    {
+    delete *i;
+    }
+}
+
+void cmFileLockPool::PushFunctionScope()
+{
+  this->FunctionScopes.push_back(new ScopePool());
+}
+
+void cmFileLockPool::PopFunctionScope()
+{
+  assert(!this->FunctionScopes.empty());
+  delete this->FunctionScopes.back();
+  this->FunctionScopes.pop_back();
+}
+
+void cmFileLockPool::PushFileScope()
+{
+  this->FileScopes.push_back(new ScopePool());
+}
+
+void cmFileLockPool::PopFileScope()
+{
+  assert(!this->FileScopes.empty());
+  delete this->FileScopes.back();
+  this->FileScopes.pop_back();
+}
+
+cmFileLockResult cmFileLockPool::LockFunctionScope(
+    const std::string& filename, unsigned timeoutSec)
+{
+  if (this->IsAlreadyLocked(filename))
+    {
+    return cmFileLockResult::MakeAlreadyLocked();
+    }
+  if (this->FunctionScopes.empty())
+    {
+    return cmFileLockResult::MakeNoFunction();
+    }
+  return this->FunctionScopes.back()->Lock(filename, timeoutSec);
+}
+
+cmFileLockResult cmFileLockPool::LockFileScope(
+    const std::string& filename, unsigned timeoutSec)
+{
+  if (this->IsAlreadyLocked(filename))
+    {
+    return cmFileLockResult::MakeAlreadyLocked();
+    }
+  assert(!this->FileScopes.empty());
+  return this->FileScopes.back()->Lock(filename, timeoutSec);
+}
+
+cmFileLockResult cmFileLockPool::LockProcessScope(
+    const std::string& filename, unsigned timeoutSec)
+{
+  if (this->IsAlreadyLocked(filename))
+    {
+    return cmFileLockResult::MakeAlreadyLocked();
+    }
+  return this->ProcessScope.Lock(filename, timeoutSec);
+}
+
+cmFileLockResult cmFileLockPool::Release(const std::string& filename)
+{
+  for (It i = this->FunctionScopes.begin();
+      i != this->FunctionScopes.end(); ++i)
+    {
+    const cmFileLockResult result = (*i)->Release(filename);
+    if (!result.IsOk())
+      {
+      return result;
+      }
+    }
+
+  for (It i = this->FileScopes.begin(); i != this->FileScopes.end(); ++i)
+    {
+    const cmFileLockResult result = (*i)->Release(filename);
+    if (!result.IsOk())
+      {
+      return result;
+      }
+    }
+
+  return this->ProcessScope.Release(filename);
+}
+
+bool cmFileLockPool::IsAlreadyLocked(const std::string& filename) const
+{
+  for (CIt i = this->FunctionScopes.begin();
+      i != this->FunctionScopes.end(); ++i)
+    {
+    const bool result = (*i)->IsAlreadyLocked(filename);
+    if (result)
+      {
+      return true;
+      }
+    }
+
+  for (CIt i = this->FileScopes.begin(); i != this->FileScopes.end(); ++i)
+    {
+    const bool result = (*i)->IsAlreadyLocked(filename);
+    if (result)
+      {
+      return true;
+      }
+    }
+
+  return this->ProcessScope.IsAlreadyLocked(filename);
+}
+
+cmFileLockPool::ScopePool::ScopePool()
+{
+}
+
+cmFileLockPool::ScopePool::~ScopePool()
+{
+  for (It i = this->Locks.begin(); i != this->Locks.end(); ++i)
+    {
+    delete *i;
+    }
+}
+
+cmFileLockResult cmFileLockPool::ScopePool::Lock(
+    const std::string& filename, unsigned timeoutSec)
+{
+  cmFileLock *lock = new cmFileLock();
+  const cmFileLockResult result = lock->Lock(filename, timeoutSec);
+  if (result.IsOk())
+    {
+    this->Locks.push_back(lock);
+    return cmFileLockResult::MakeOk();
+    }
+  else
+    {
+    delete lock;
+    return result;
+    }
+}
+
+cmFileLockResult cmFileLockPool::ScopePool::Release(
+    const std::string& filename)
+{
+  for (It i = this->Locks.begin(); i != this->Locks.end(); ++i)
+    {
+    if ((*i)->IsLocked(filename))
+      {
+      return (*i)->Release();
+      }
+    }
+  return cmFileLockResult::MakeOk();
+}
+
+bool cmFileLockPool::ScopePool::IsAlreadyLocked(
+    const std::string& filename) const
+{
+  for (CIt i = this->Locks.begin(); i != this->Locks.end(); ++i)
+    {
+    if ((*i)->IsLocked(filename))
+      {
+      return true;
+      }
+    }
+  return false;
+}
diff --git a/Source/cmFileLockPool.h b/Source/cmFileLockPool.h
new file mode 100644
index 0000000..a63540c
--- /dev/null
+++ b/Source/cmFileLockPool.h
@@ -0,0 +1,100 @@
+/*============================================================================
+  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.
+============================================================================*/
+#ifndef cmFileLockPool_h
+#define cmFileLockPool_h
+
+#include "cmStandardIncludes.h"
+
+class cmFileLockResult;
+class cmFileLock;
+
+class cmFileLockPool
+{
+ public:
+  cmFileLockPool();
+  ~cmFileLockPool();
+
+  //@{
+  /**
+    * @brief Function scope control.
+    */
+  void PushFunctionScope();
+  void PopFunctionScope();
+  //@}
+
+  //@{
+  /**
+    * @brief File scope control.
+    */
+  void PushFileScope();
+  void PopFileScope();
+  //@}
+
+  //@{
+  /**
+    * @brief Lock the file in given scope.
+    * @param timeoutSec Lock timeout. If -1 try until success or fatal error.
+    */
+  cmFileLockResult LockFunctionScope(
+      const std::string& filename, unsigned timeoutSec
+  );
+  cmFileLockResult LockFileScope(
+      const std::string& filename, unsigned timeoutSec
+  );
+  cmFileLockResult LockProcessScope(
+      const std::string& filename, unsigned timeoutSec
+  );
+  //@}
+
+  /**
+    * @brief Unlock the file explicitly.
+    */
+  cmFileLockResult Release(const std::string& filename);
+
+ private:
+  cmFileLockPool(const cmFileLockPool&);
+  cmFileLockPool& operator=(const cmFileLockPool&);
+
+  bool IsAlreadyLocked(const std::string& filename) const;
+
+  class ScopePool
+  {
+   public:
+    ScopePool();
+    ~ScopePool();
+
+    cmFileLockResult Lock(const std::string& filename, unsigned timeoutSec);
+    cmFileLockResult Release(const std::string& filename);
+    bool IsAlreadyLocked(const std::string& filename) const;
+
+   private:
+    ScopePool(const ScopePool&);
+    ScopePool& operator=(const ScopePool&);
+
+    typedef std::list<cmFileLock*> List;
+    typedef List::iterator It;
+    typedef List::const_iterator CIt;
+
+    List Locks;
+  };
+
+  typedef std::list<ScopePool*> List;
+
+  typedef List::iterator It;
+  typedef List::const_iterator CIt;
+
+  List FunctionScopes;
+  List FileScopes;
+  ScopePool ProcessScope;
+};
+
+#endif // cmFileLockPool_h
diff --git a/Source/cmFileLockResult.cxx b/Source/cmFileLockResult.cxx
new file mode 100644
index 0000000..045e7ee
--- /dev/null
+++ b/Source/cmFileLockResult.cxx
@@ -0,0 +1,111 @@
+/*============================================================================
+  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 "cmFileLockResult.h"
+
+#include <errno.h>
+
+cmFileLockResult cmFileLockResult::MakeOk()
+{
+  return cmFileLockResult(OK, 0);
+}
+
+cmFileLockResult cmFileLockResult::MakeSystem()
+{
+#if defined(_WIN32)
+  const Error lastError = GetLastError();
+#else
+  const Error lastError = errno;
+#endif
+  return cmFileLockResult(SYSTEM, lastError);
+}
+
+cmFileLockResult cmFileLockResult::MakeTimeout()
+{
+  return cmFileLockResult(TIMEOUT, 0);
+}
+
+cmFileLockResult cmFileLockResult::MakeAlreadyLocked()
+{
+  return cmFileLockResult(ALREADY_LOCKED, 0);
+}
+
+cmFileLockResult cmFileLockResult::MakeInternal()
+{
+  return cmFileLockResult(INTERNAL, 0);
+}
+
+cmFileLockResult cmFileLockResult::MakeNoFunction()
+{
+  return cmFileLockResult(NO_FUNCTION, 0);
+}
+
+bool cmFileLockResult::IsOk() const
+{
+  return this->Type == OK;
+}
+
+std::string cmFileLockResult::GetOutputMessage() const
+{
+  switch (this->Type)
+    {
+    case OK:
+      return "0";
+    case SYSTEM:
+#if defined(_WIN32)
+      {
+      char* errorText = NULL;
+
+      // http://stackoverflow.com/a/455533/2288008
+      DWORD flags = FORMAT_MESSAGE_FROM_SYSTEM |
+          FORMAT_MESSAGE_ALLOCATE_BUFFER |
+          FORMAT_MESSAGE_IGNORE_INSERTS;
+      ::FormatMessageA(
+          flags,
+          NULL,
+          this->ErrorValue,
+          MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+          (LPSTR)&errorText,
+          0,
+          NULL
+      );
+
+      if (errorText != NULL)
+        {
+        const std::string message = errorText;
+        ::LocalFree(errorText);
+        return message;
+        }
+      else
+        {
+        return "Internal error (FormatMessageA failed)";
+        }
+      }
+#else
+      return strerror(this->ErrorValue);
+#endif
+    case TIMEOUT:
+      return "Timeout reached";
+    case ALREADY_LOCKED:
+      return "File already locked";
+    case NO_FUNCTION:
+      return "'GUARD FUNCTION' not used in function definition";
+    case INTERNAL:
+    default:
+      return "Internal error";
+    }
+}
+
+cmFileLockResult::cmFileLockResult(ErrorType typeValue, Error errorValue):
+    Type(typeValue), ErrorValue(errorValue)
+{
+}
diff --git a/Source/cmFileLockResult.h b/Source/cmFileLockResult.h
new file mode 100644
index 0000000..531fb49
--- /dev/null
+++ b/Source/cmFileLockResult.h
@@ -0,0 +1,85 @@
+/*============================================================================
+  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.
+============================================================================*/
+
+#ifndef cmFileLockResult_h
+#define cmFileLockResult_h
+
+#include "cmStandardIncludes.h"
+
+#if defined(_WIN32)
+# include <windows.h> // DWORD
+#endif
+
+/**
+  * @brief Result of the locking/unlocking file.
+  * @note See @c cmFileLock
+  */
+class cmFileLockResult
+{
+ public:
+#if defined(_WIN32)
+  typedef DWORD Error;
+#else
+  typedef int Error;
+#endif
+
+  /**
+    * @brief Successful lock/unlock.
+    */
+  static cmFileLockResult MakeOk();
+
+  /**
+    * @brief Lock/Unlock failed. Read error/GetLastError.
+    */
+  static cmFileLockResult MakeSystem();
+
+  /**
+    * @brief Lock/Unlock failed. Timeout reached.
+    */
+  static cmFileLockResult MakeTimeout();
+
+  /**
+    * @brief File already locked.
+    */
+  static cmFileLockResult MakeAlreadyLocked();
+
+  /**
+    * @brief Internal error.
+    */
+  static cmFileLockResult MakeInternal();
+
+  /**
+    * @brief Try to lock with function guard outside of the function
+    */
+  static cmFileLockResult MakeNoFunction();
+
+  bool IsOk() const;
+  std::string GetOutputMessage() const;
+
+ private:
+  enum ErrorType
+  {
+    OK,
+    SYSTEM,
+    TIMEOUT,
+    ALREADY_LOCKED,
+    INTERNAL,
+    NO_FUNCTION
+  };
+
+  cmFileLockResult(ErrorType type, Error errorValue);
+
+  ErrorType Type;
+  Error ErrorValue;
+};
+
+#endif // cmFileLockResult_h
diff --git a/Source/cmFileLockUnix.cxx b/Source/cmFileLockUnix.cxx
new file mode 100644
index 0000000..038011e
--- /dev/null
+++ b/Source/cmFileLockUnix.cxx
@@ -0,0 +1,102 @@
+/*============================================================================
+  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 <errno.h> // errno
+#include <stdio.h> // SEEK_SET
+#include <fcntl.h>
+#include "cmSystemTools.h"
+
+cmFileLock::cmFileLock(): File(-1)
+{
+}
+
+cmFileLockResult cmFileLock::Release()
+{
+  if (this->Filename.empty())
+    {
+    return cmFileLockResult::MakeOk();
+    }
+  const int lockResult = this->LockFile(F_SETLK, F_UNLCK);
+
+  this->Filename = "";
+
+  if (lockResult == 0)
+    {
+    return cmFileLockResult::MakeOk();
+    }
+  else
+    {
+    return cmFileLockResult::MakeSystem();
+    }
+}
+
+cmFileLockResult cmFileLock::OpenFile()
+{
+  this->File = ::open(this->Filename.c_str(), O_RDWR);
+  if (this->File == -1)
+    {
+    return cmFileLockResult::MakeSystem();
+    }
+  else
+    {
+    return cmFileLockResult::MakeOk();
+    }
+}
+
+cmFileLockResult cmFileLock::LockWithoutTimeout()
+{
+  if (this->LockFile(F_SETLKW, F_WRLCK) == -1)
+    {
+    return cmFileLockResult::MakeSystem();
+    }
+  else
+    {
+    return cmFileLockResult::MakeOk();
+    }
+}
+
+cmFileLockResult cmFileLock::LockWithTimeout(unsigned seconds)
+{
+  while (true)
+    {
+    if (this->LockFile(F_SETLK, F_WRLCK) == -1)
+      {
+      if (errno != EACCES && errno != EAGAIN)
+        {
+        return cmFileLockResult::MakeSystem();
+        }
+      }
+    else
+      {
+      return cmFileLockResult::MakeOk();
+      }
+    if (seconds == 0)
+      {
+      return cmFileLockResult::MakeTimeout();
+      }
+    --seconds;
+    cmSystemTools::Delay(1000);
+    }
+}
+
+int cmFileLock::LockFile(int cmd, int type)
+{
+  struct ::flock lock;
+  lock.l_start = 0;
+  lock.l_len = 0; // lock all bytes
+  lock.l_pid = 0; // unused (for F_GETLK only)
+  lock.l_type = static_cast<short>(type); // exclusive lock
+  lock.l_whence = SEEK_SET;
+  return ::fcntl(this->File, cmd, &lock);
+}
diff --git a/Source/cmFileLockWin32.cxx b/Source/cmFileLockWin32.cxx
new file mode 100644
index 0000000..17231ea
--- /dev/null
+++ b/Source/cmFileLockWin32.cxx
@@ -0,0 +1,126 @@
+/*============================================================================
+  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 <windows.h> // CreateFileW
+#include "cmSystemTools.h"
+
+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 = "";
+
+  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 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
+  );
+}
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 926efe7..6b75298 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -23,6 +23,7 @@
 #include "cmGeneratorExpression.h"
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
+# include "cmFileLockPool.h"
 # include <cmsys/hash_map.hxx>
 #endif
 
@@ -348,6 +349,10 @@ public:
   std::set<cmTarget const*> const&
   GetFilenameTargetDepends(cmSourceFile* sf) const;
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  cmFileLockPool& GetFileLockPool() { return FileLockPool; }
+#endif
+
 protected:
   virtual void Generate();
 
@@ -499,6 +504,11 @@ private:
 
   mutable std::map<cmSourceFile*, std::set<cmTarget const*> >
   FilenameTargetDepends;
+
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  // Pool of file locks
+  cmFileLockPool FileLockPool;
+#endif
 };
 
 #endif
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 3fb1e1e..2de6c93 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -79,9 +79,15 @@ public:
     this->GG = lg->GetGlobalGenerator();
     this->LG = this->GG->GetCurrentLocalGenerator();
     this->GG->SetCurrentLocalGenerator(lg);
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+    this->GG->GetFileLockPool().PushFileScope();
+#endif
     }
   ~cmLocalGeneratorCurrent()
     {
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+    this->GG->GetFileLockPool().PopFileScope();
+#endif
     this->GG->SetCurrentLocalGenerator(this->LG);
     }
 };
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 53fd56f..2506eaa 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -4522,10 +4522,20 @@ void cmMakefile::PushScope()
   this->Internal->VarUsageStack.push(usage);
 
   this->PushLoopBlockBarrier();
+
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  this->GetLocalGenerator()->GetGlobalGenerator()->
+    GetFileLockPool().PushFunctionScope();
+#endif
 }
 
 void cmMakefile::PopScope()
 {
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+  this->GetLocalGenerator()->GetGlobalGenerator()->
+    GetFileLockPool().PopFunctionScope();
+#endif
+
   this->PopLoopBlockBarrier();
 
   cmDefinitions* current = &this->Internal->VarStack.top();