libi2ncommon: (reinhard) added pointer_func and signalfunc modules.

[libi2ncommon] / src / daemonfunc.cpp

/***************************************************************************
 *   Copyright (C) 2008 by Intra2net AG - Thomas Jarosch                   *
 *   thomas.jarosch@intra2net.com                                          *
 *   http://www.intra2net.com                                              *
 ***************************************************************************/
#include <sys/types.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>

#include <string>
#include <stdexcept>
#include "daemonfunc.hpp"
#include "stringfunc.hxx"
#include "filefunc.hxx"


namespace I2n
{
namespace Daemon
{

using namespace std;

/**
 * Fork into the background.
 */
void daemonize()
{
   int pid=fork();

   if (pid < 0)
   {
      throw runtime_error("fork() failed");
   }
   if (pid > 0)
   {
      // parent process
      exit (0);
   }
   // pid==0 -> child process: continue
}

/**
 * Drop root privileges
 * @param username User to become. Don't change user if empty
 * @param group Group to become. Don't change group if empty
 * @param get_group_from_user Get group GID from user information if group is empty.
 * @return true if all is fine, false otherwise
 */
bool drop_root_privileges(const std::string &username,
                          const std::string &group, bool get_group_from_user)
{
   if (!group.empty())
   {
      Group my_group(group);
      if (!my_group.is_valid())
         return false;

      if (setgid((my_group.Gid)))
         return false;
   }

   if (!username.empty())
   {
      User my_user(username);
      if (!my_user.is_valid())
         return false;

      if (get_group_from_user && group.empty())
      {
         if (setgid((my_user.Gid)))
            return false;
      }

      if (setuid(my_user.Uid))
         return false;
   }
}

/**
 * @brief determine the pids for a given program
 * @param[in] name name (or full path) of the binary
 * @param[out] result the pids associated with the name.
 * @return @a true if the function performed without errors.
 *
 * Walk though the /proc/\<pid\>'s and search for the name.
 *
 * @note Since this function uses /proc, it's system specific. Currently:
 * Linux only!
 *
 * @todo check cmdline and stat in /proc/\<pid\> dir for the searched name.
 */
bool pid_of(const std::string& name, std::vector< pid_t >& result)
{
   std::vector< std::string > entries;
   std::vector< pid_t > fuzz1_result;
   std::vector< pid_t > fuzz2_result;
   result.clear();
   if (!get_dir("/proc", entries)) return false;
   for (std::vector< std::string >::const_iterator it= entries.begin();
         it != entries.end();
         ++it)
   {
      pid_t pid;
      if (! string_to<pid_t>(*it, pid)) continue;
      std::string base_path= std::string("/proc/") + *it;
      std::string exe_path= base_path + "/exe";
      I2n::Stat stat(exe_path, false);
      if (not stat or not stat.is_link()) continue;
      std::string real_exe= read_link(exe_path);
      if (real_exe == name)
      {
         result.push_back( pid );
         continue;
      }

      std::string proc_stat= read_file( base_path + "/stat");
      if (proc_stat.empty()) continue; // process vanished

      //TODO some more fuzz tests here?! (cmdline, stat(us))

      if (basename(real_exe) == name)
      {
         fuzz2_result.push_back(pid);
         continue;
      }
   }
   if (result.empty())
   {
      result.swap(fuzz1_result);
   }
   if (result.empty())
   {
      result.swap(fuzz2_result);
   }
   return true;
} // eo pidOf(const std::string&,std::vector< pid_t >&)

}
}