implemented wxSingleInstanceChecker for Unix
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@10463 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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Vadim Zeitlin
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src/unix/snglinst.cpp
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321
src/unix/snglinst.cpp
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///////////////////////////////////////////////////////////////////////////////
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// Name: unix/snglinst.cpp
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// Purpose: implements wxSingleInstanceChecker class for Unix using
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// lock files with fcntl(2) or flock(2)
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// Author: Vadim Zeitlin
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// Modified by:
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// Created: 09.06.01
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// RCS-ID: $Id$
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// Copyright: (c) 2001 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
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// License: wxWindows license
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///////////////////////////////////////////////////////////////////////////////
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// ============================================================================
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// declarations
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// ============================================================================
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// ----------------------------------------------------------------------------
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// headers
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// ----------------------------------------------------------------------------
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#ifdef __GNUG__
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#pragma implementation "snglinst.h"
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#endif
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// For compilers that support precompilation, includes "wx.h".
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#include "wx/wxprec.h"
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#ifdef __BORLANDC__
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#pragma hdrstop
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#endif
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#if wxUSE_SNGLINST_CHECKER
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#ifndef WX_PRECOMP
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#include "wx/string.h"
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#include "wx/log.h"
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#include "wx/intl.h"
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#include "wx/file.h"
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#endif //WX_PRECOMP
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#include "wx/utils.h" // wxGetHomeDir()
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#include "wx/snglinst.h"
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <signal.h> // for kill()
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#ifdef HAVE_FCNTL
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#include <fcntl.h>
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#elif defined(HAVE_FLOCK)
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#include <sys/file.h>
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#else
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// normally, wxUSE_SNGLINST_CHECKER must have been reset by configure
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#error "wxSingleInstanceChecker can't be compiled on this platform"
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#endif // fcntl()/flock()
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// ----------------------------------------------------------------------------
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// private functions: (exclusively) lock/unlock the file
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// ----------------------------------------------------------------------------
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enum LockOperation
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{
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LOCK,
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UNLOCK
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};
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#ifdef HAVE_FCNTL
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static int wxLockFile(int fd, LockOperation lock)
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{
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// init the flock parameter struct
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struct flock fl;
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fl.l_type = lock == LOCK ? F_WRLCK : F_UNLCK;
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// lock the entire file
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fl.l_whence =
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fl.l_start =
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fl.l_len = 0;
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// is this needed?
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fl.l_pid = getpid();
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return fcntl(fd, F_SETLK, &fl);
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}
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#else // HAVE_FLOCK
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static int wxLockFile(int fd, LockOperation lock)
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{
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return flock(fd, lock == LOCK ? LOCK_EX | LOCK_NB : LOCK_UN);
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}
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#endif // fcntl()/flock()
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// ----------------------------------------------------------------------------
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// wxSingleInstanceCheckerImpl: the real implementation class
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// ----------------------------------------------------------------------------
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class wxSingleInstanceCheckerImpl
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{
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public:
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wxSingleInstanceCheckerImpl()
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{
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m_fdLock = -1;
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m_pidLocker = 0;
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}
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bool Create(const wxString& name);
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pid_t GetLockerPID() const { return m_pidLocker; }
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~wxSingleInstanceCheckerImpl() { Unlock(); }
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private:
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// try to create and lock the file
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bool CreateLockFile();
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// unlock and remove the lock file
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void Unlock();
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// the descriptor of our lock file, -1 if none
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int m_fdLock;
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// pid of the process owning the lock file
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pid_t m_pidLocker;
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// the name of the lock file
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wxString m_nameLock;
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};
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// ============================================================================
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// wxSingleInstanceCheckerImpl implementation
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// ============================================================================
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bool wxSingleInstanceCheckerImpl::CreateLockFile()
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{
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// try to open the file
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m_fdLock = open(m_nameLock,
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O_WRONLY | O_CREAT | O_EXCL,
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S_IREAD | S_IWRITE);
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if ( m_fdLock != -1 )
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{
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// try to lock it
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if ( wxLockFile(m_fdLock, LOCK) == 0 )
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{
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// fine, we have the exclusive lock to the file, write our PID
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// into it
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m_pidLocker = getpid();
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// use char here, not wxChar!
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char buf[256]; // enough for any PID size
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int len = sprintf(buf, "%d", m_pidLocker) + 1;
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if ( write(m_fdLock, buf, len) != len )
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{
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wxLogSysError(_("Failed to write to lock file '%s'"),
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m_nameLock.c_str());
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Unlock();
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return FALSE;
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}
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fsync(m_fdLock);
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return TRUE;
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}
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// couldn't lock: this might have happened because of a race
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// condition: maybe another instance opened and locked the file
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// between our calls to open() and flock()
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close(m_fdLock);
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m_fdLock = -1;
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}
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// we didn't create and lock the file
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return FALSE;
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}
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bool wxSingleInstanceCheckerImpl::Create(const wxString& name)
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{
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m_nameLock = name;
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if ( CreateLockFile() )
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{
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// nothing more to do
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return TRUE;
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}
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// try to open the file for reading and get the PID of the process
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// which has it
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wxFile file(name, wxFile::read);
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if ( !file.IsOpened() )
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{
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// well, this is really weird - file doesn't exist and we can't
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// create it
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//
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// normally, this just means that we don't have write access to
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// the directory where we try to create it, so return failure,
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// even it might also be a rare case of a race condition when
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// another process managed to open and lock the file and terminate
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// (erasing it) before we got here, but this should happen so
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// rarely in practice that we don't care
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wxLogError(_("Failed to access lock file."));
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return FALSE;
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}
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char buf[256];
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off_t count = file.Read(buf, WXSIZEOF(buf));
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if ( count == wxInvalidOffset )
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{
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wxLogError(_("Failed to read PID from lock file."));
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}
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else
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{
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if ( sscanf(buf, "%d", &m_pidLocker) == 1 )
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{
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if ( kill(m_pidLocker, 0) != 0 )
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{
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if ( unlink(name) != 0 )
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{
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wxLogError(_("Failed to remove stale lock file '%s'."),
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name.c_str());
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// return TRUE in this case for now...
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}
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else
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{
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wxLogMessage(_("Deleted stale lock file '%s'."),
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name.c_str());
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// retry now
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(void)CreateLockFile();
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}
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}
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//else: the other process is running
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}
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else
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{
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wxLogWarning(_("Invalid lock file '%s'."));
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}
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}
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// return TRUE if we could get the PID of the process owning the lock file
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// (whether it is still running or not), FALSE otherwise as it is
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// unexpected
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return m_pidLocker != 0;
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}
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void wxSingleInstanceCheckerImpl::Unlock()
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{
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if ( m_fdLock != -1 )
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{
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if ( unlink(m_nameLock) != 0 )
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{
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wxLogSysError(_("Failed to remove lock file '%s'"),
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m_nameLock.c_str());
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}
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if ( wxLockFile(m_fdLock, UNLOCK) != 0 )
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{
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wxLogSysError(_("Failed to unlock lock file '%s'"),
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m_nameLock.c_str());
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}
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if ( close(m_fdLock) != 0 )
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{
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wxLogSysError(_("Failed to close lock file '%s'"),
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m_nameLock.c_str());
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}
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}
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m_pidLocker = 0;
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}
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// ============================================================================
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// wxSingleInstanceChecker implementation
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// ============================================================================
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bool wxSingleInstanceChecker::Create(const wxString& name,
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const wxString& path)
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{
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wxASSERT_MSG( !m_impl,
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_T("calling wxSingleInstanceChecker::Create() twice?") );
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// must have the file name to create a lock file
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wxASSERT_MSG( !name.empty(), _T("lock file name can't be empty") );
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m_impl = new wxSingleInstanceCheckerImpl;
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wxString fullname = path;
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if ( fullname.empty() )
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{
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fullname << wxGetHomeDir() << _T('/');
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}
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fullname << name;
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return m_impl->Create(fullname);
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}
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bool wxSingleInstanceChecker::IsAnotherRunning() const
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{
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wxCHECK_MSG( m_impl, FALSE, _T("must call Create() first") );
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// if another instance is running, it must own the lock file - otherwise
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// we have it and the locker PID is ours one
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return m_impl->GetLockerPID() != getpid();
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}
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wxSingleInstanceChecker::~wxSingleInstanceChecker()
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{
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delete m_impl;
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}
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#endif // wxUSE_SNGLINST_CHECKER
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