lockfile.cpp

贡献一份commoncpp2,有兴趣的可以研究一下

// Copyright (C) 1999-2005 Open Source Telecom Corporation.
//
// 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, write to the Free Software 
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
// 
// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however    
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.    
//
// This exception applies only to the code released under the name GNU
// Common C++.  If you copy code from other releases into a copy of GNU
// Common C++, as the General Public License permits, the exception does
// not apply to the code that you add in this way.  To avoid misleading
// anyone as to the status of such modified files, you must delete
// this exception notice from them.
//
// If you write modifications of your own for GNU Common C++, it is your choice
// whether to permit this exception to apply to your modifications.
// If you do not wish that, delete this exception notice.
//

#include <cc++/config.h>
#include <cc++/export.h>
#include <cc++/thread.h>
#include <cc++/process.h>
#include <cc++/strchar.h>

#include <sys/stat.h>
#include <cstdlib>
#include <cstdio>
#include <cerrno>

#ifdef	CCXX_NAMESPACES
namespace ost {
#endif

#ifdef	WIN32

Lockfile::Lockfile()
{
	_mutex = INVALID_HANDLE_VALUE;
	_flagged = false;
}

Lockfile::Lockfile(const char *name)
{
	_mutex = INVALID_HANDLE_VALUE;
	_flagged = false;
	lock(name);
}

bool Lockfile::lock(const char *name)
{
	char mname[65];
	char *ext = strrchr(name, '/');
	
	if(ext)
		name = ++ext;
	
	unlock();
	snprintf(mname, sizeof(mname) - 4, "_lock_%s", name);
	ext = strrchr(mname, '.');
	if(ext && !stricmp(ext, ".lock"))
	{
		*ext = 0;
		ext = NULL;
	}
	if(!ext)
		addString(mname, sizeof(mname), ".lck");
	_mutex = CreateMutex(NULL, FALSE, mname);
	if(WaitForSingleObject(_mutex, 200) == WAIT_OBJECT_0)
		_flagged = true;
	return _flagged;
}

void Lockfile::unlock(void)
{
	if(_mutex == INVALID_HANDLE_VALUE)
		return;

	if(_flagged)
		ReleaseMutex(_mutex);
	CloseHandle(_mutex);
	_flagged = false;
	_mutex = INVALID_HANDLE_VALUE;
}

bool Lockfile::isLocked(void)
{
	return _flagged;
}

#else

Lockfile::Lockfile()
{
	_path = NULL;
}

Lockfile::Lockfile(const char *name)
{
	_path = NULL;
	lock(name);
}

bool Lockfile::lock(const char *name)
{
	struct stat ino;
	int fd, pid, status;
	const char *ext;
	char buffer[128];

	unlock();

	ext = strrchr(name, '/');
	if(ext)
		ext = strrchr(ext, '.');
	else
		ext = strrchr(name, '.');

	if(strchr(name, '/'))
	{
		_path = new char[strlen(name) + 1];
		strcpy(_path, name);
	}
	else if(ext && !stricmp(ext, ".pid"))
	{
		if(stat("/var/run", &ino))
			snprintf(buffer, sizeof(buffer), "/tmp/.%s", name);
		else
			snprintf(buffer, sizeof(buffer), "/var/run/%s", name);
		_path = new char[strlen(buffer) + 1];
		strcpy(_path, buffer);
	}	
	else
	{
		if(!ext)
			ext = ".lock";
		if(stat("/var/lock", &ino))
			snprintf(buffer, sizeof(buffer), "/tmp/.%s%s", name, ext);
		else
			snprintf(buffer, sizeof(buffer), "/var/lock/%s%s", name, ext);

		_path = new char[strlen(buffer) + 1];
		strcpy(_path, buffer);
	}

	for(;;)
	{
		fd = ::open(_path, O_WRONLY | O_CREAT | O_EXCL, 0660);
		if(fd > 0)
		{
			pid = getpid();
			snprintf(buffer, sizeof(buffer), "%d\n", pid);
			::write(fd, buffer, strlen(buffer));
			::close(fd);
			return true;
		}
		if(fd < 0 && errno != EEXIST)
		{
			delete[] _path;
			return false;
		}

		fd = ::open(_path, O_RDONLY);
		if(fd < 0)
		{
			if(errno == ENOENT)
				continue;
			delete[] _path;
			return false;
		}

		Thread::sleep(2000);
		status = ::read(fd, buffer, sizeof(buffer) - 1);
		if(status < 1)
		{
			::close(fd);
			continue;
		}

		buffer[status] = 0;
		pid = atoi(buffer);
		if(pid)
		{
			if(pid == getpid())
			{
				status = -1;
				errno = 0;
			}
			else
				status = kill(pid, 0);

			if(!status || (errno == EPERM))
			{
				::close(fd);
				delete[] _path;
				return false;
			}
		}
		::close(fd);
		::unlink(_path);
	}
}		

void Lockfile::unlock(void)
{
	if(_path)
	{
		remove(_path);
		delete[] _path;
		_path = NULL;
	}
}	

bool Lockfile::isLocked(void)
{
	if(_path)
		return true;

	return false;
}

#endif

#ifdef	CCXX_NAMESPACES
}
#endif

/** EMACS **
 * Local variables:
 * mode: c++
 * c-basic-offset: 8
 * End:
 */