lockfile.h

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2023 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
#ifndef INCLUDE__LOCK_FILE_H_
#define INCLUDE__LOCK_FILE_H_
 
#include <wx/wx.h>
#include <wx/file.h>
#include <wx/filefn.h>
#include <wx/log.h>
#include <wx/filename.h>
#include <nlohmann/json.hpp>
#include <wildcards_and_files_ext.h>
 
#define LCK "KICAD_LOCKING"
 
class LOCKFILE
{
public:
 LOCKFILE( const wxString &filename, bool aRemoveOnRelease = true ) :
 m_originalFile( filename ), m_fileCreated( false ), m_status( false ),
 m_removeOnRelease( aRemoveOnRelease ), m_errorMsg( "" )
 {
 if( filename.IsEmpty() )
 return;
 
 wxLogTrace( LCK, "Trying to lock %s", filename );
 wxFileName fn( filename );
 fn.SetName( FILEEXT::LockFilePrefix + fn.GetName() );
 fn.SetExt( fn.GetExt() + '.' + FILEEXT::LockFileExtension );
 
 if( !fn.IsDirWritable() )
 {
 wxLogTrace( LCK, "File is not writable: %s", filename );
 m_status = true;
 m_removeOnRelease = false;
 return;
 }
 
 m_lockFilename = fn.GetFullPath();
 
 wxFile file;
 try
 {
 bool lock_success = false;
 bool rw_success = false;
 
 {
 wxLogNull suppressExpectedErrorMessages;
 
 lock_success = file.Open( m_lockFilename, wxFile::write_excl );
 
 if( !lock_success )
 rw_success = file.Open( m_lockFilename, wxFile::read );
 }
 
 if( lock_success )
 {
 // Lock file doesn't exist, create one
 m_fileCreated = true;
 m_status = true;
 m_username = wxGetUserId();
 m_hostname = wxGetHostName();
 nlohmann::json j;
 j["username"] = std::string( m_username.mb_str() );
 j["hostname"] = std::string( m_hostname.mb_str() );
 std::string lock_info = j.dump();
 file.Write( lock_info );
 file.Close();
 wxLogTrace( LCK, "Locked %s", filename );
 }
 else if( rw_success )
 {
 // Lock file already exists, read the details
 wxString lock_info;
 file.ReadAll( &lock_info );
 nlohmann::json j = nlohmann::json::parse( std::string( lock_info.mb_str() ) );
 m_username = wxString( j["username"].get<std::string>() );
 m_hostname = wxString( j["hostname"].get<std::string>() );
 file.Close();
 m_errorMsg = _( "Lock file already exists" );
 wxLogTrace( LCK, "Existing Lock for %s", filename );
 }
 else
 {
 throw std::runtime_error( "Failed to open lock file" );
 }
 }
 catch( std::exception& e )
 {
 wxLogError( "Got an error trying to lock %s: %s", filename, e.what() );
 
 // Delete lock file if it was created above but we threw an exception somehow
 if( m_fileCreated )
 {
 wxRemoveFile( m_lockFilename );
 m_fileCreated = false; // Reset the flag since file has been deleted manually
 }
 
 m_errorMsg = _( "Failed to access lock file" );
 m_status = false;
 }
 }
 
 ~LOCKFILE()
 {
 UnlockFile();
 }
 
 void UnlockFile()
 {
 wxLogTrace( LCK, "Unlocking %s", m_lockFilename );
 
 // Delete lock file only if the file was created in the constructor and if the file contains the correct user and host names
 if( m_fileCreated && checkUserAndHost() )
 {
 if( m_removeOnRelease )
 wxRemoveFile( m_lockFilename );
 
 m_fileCreated = false; // Reset the flag since file has been deleted manually
 m_status = false;
 m_errorMsg = wxEmptyString;
 }
 }
 
 bool OverrideLock( bool aRemoveOnRelease = true )
 {
 wxLogTrace( LCK, "Overriding lock on %s", m_lockFilename );
 
 if( !m_fileCreated )
 {
 try
 {
 wxFile file;
 bool success = false;
 
 {
 wxLogNull suppressExpectedErrorMessages;
 success = file.Open( m_lockFilename, wxFile::write );
 }
 
 if( success )
 {
 m_username = wxGetUserId();
 m_hostname = wxGetHostName();
 nlohmann::json j;
 j["username"] = std::string( m_username.mb_str() );
 j["hostname"] = std::string( m_hostname.mb_str() );
 std::string lock_info = j.dump();
 file.Write( lock_info );
 file.Close();
 m_fileCreated = true;
 m_status = true;
 m_removeOnRelease = aRemoveOnRelease;
 m_errorMsg = wxEmptyString;
 wxLogTrace( LCK, "Successfully overrode lock on %s", m_lockFilename );
 return true;
 }
 
 return false;
 }
 catch( std::exception& e )
 {
 wxLogError( "Got exception trying to override lock on %s: %s",
 m_lockFilename, e.what() );
 
 return false;
 }
 }
 else
 {
 wxLogTrace( LCK, "Upgraded lock on %s to delete on release", m_lockFilename );
 m_removeOnRelease = aRemoveOnRelease;
 }
 
 return true;
 }
 
 bool IsLockedByMe()
 {
 return m_username == wxGetUserId() && m_hostname == wxGetHostName();
 }
 
 wxString GetUsername(){ return m_username; }
 
 wxString GetHostname(){ return m_hostname; }
 
 wxString GetErrorMsg(){ return m_errorMsg; }
 
 bool Locked() const
 {
 return m_fileCreated;
 }
 
 bool Valid() const
 {
 return m_status;
 }
 
 explicit operator bool() const
 {
 return m_status;
 }
 
private:
 wxString m_originalFile;
 wxString m_lockFilename;
 wxString m_username;
 wxString m_hostname;
 bool m_fileCreated;
 bool m_status;
 bool m_removeOnRelease;
 wxString m_errorMsg;
 
 bool checkUserAndHost()
 {
 wxFileName fileName( m_lockFilename );
 
 if( !fileName.FileExists() )
 {
 wxLogTrace( LCK, "File does not exist: %s", m_lockFilename );
 return false;
 }
 
 wxFile file;
 try
 {
 if( file.Open( m_lockFilename, wxFile::read ) )
 {
 wxString lock_info;
 file.ReadAll( &lock_info );
 nlohmann::json j = nlohmann::json::parse( std::string( lock_info.mb_str() ) );
 
 if( m_username == wxString( j["username"].get<std::string>() )
 && m_hostname == wxString( j["hostname"].get<std::string>() ) )
 {
 wxLogTrace( LCK, "User and host match for lock %s", m_lockFilename );
 return true;
 }
 }
 }
 catch( std::exception &e )
 {
 wxLogError( "Got exception trying to check user/host for lock on %s: %s",
 m_lockFilename,
 e.what() );
 }
 
 wxLogTrace( LCK, "User and host DID NOT match for lock %s", m_lockFilename );
 return false;
 }
};
 
 
#endif // INCLUDE__LOCK_FILE_H_