Merge branch 'daemon-ext'

[libi2ncommon] / src / pidfile.cpp

/*
The software in this package is distributed under the GNU General
Public License version 2 (with a special exception described below).

A copy of GNU General Public License (GPL) is included in this distribution,
in the file COPYING.GPL.

As a special exception, if other files instantiate templates or use macros
or inline functions from this file, or you compile this file and link it
with other works to produce a work based on this file, this file
does not by itself cause the resulting work to be covered
by the GNU General Public License.

However the source code for this file must still be made available
in accordance with section (3) of the GNU General Public License.

This exception does not invalidate any other reasons why a work based
on this file might be covered by the GNU General Public License.
*/
/**
   Pid file handling

   @copyright Intra2net AG
*/
#include "pidfile.hpp"
#include <sys/types.h>

#include <signal.h>
#include <fstream>
#include <sstream>
#include <iostream>
#include <stdexcept>

#include "filefunc.hxx"
#include <unistd.h>

using namespace std;
using namespace I2n;

/**
 * Constructor.
 * @param filename Full path to the pid file
 * @param remove_file_on_destruction Remove pid file on destruction of the object. Only useful if running as root.
 */
PidFile::PidFile(const std::string &filename, bool remove_file_on_destruction)
{
   Filename = filename;
   RemoveFileOnDestruction = remove_file_on_destruction;
   WroteFile = false;
}

/**
 * Destructor. We delete the pid file if #RemoveFileOnDestruction is set
 * and we actually wrote a file (#WroteFile).
 * This is only possible if we run with root priviledges as /var/run
 * is root writable only.
 */
PidFile::~PidFile()
{
   if (RemoveFileOnDestruction && WroteFile)
      unlink(Filename);
}

/**
 * Checks if the pid file for this program already exists.
 * If yes it does a "kill" probe to see if it is alive.
 * @param running_pid[out] Store pid number of instance if already running
 * @return true if running, false otherweise
 */
bool PidFile::check_already_running(pid_t *running_pid)
{
   // Check if there is an existing pid file
   ifstream in(Filename.c_str());
   if (!in)
      return false;

   pid_t read_pid = 0;
   if (!(in >> read_pid))
      return false;

   // Ok, we got an existing pid file.
   // Check if program is still alive
   if (kill(read_pid, 0) == 0)
   {
      if (running_pid)
         *running_pid = read_pid;

      // State: running
      return true;
   }

   // Default state: not running
   return false;
}

/**
 * Write pid file
 * @return true if file was written, false otherwise
 */
bool PidFile::write()
{
   ofstream out(Filename.c_str());
   if (!out)
      return false;

   out << getpid() << endl;

   WroteFile = true;

   return true;
}