libi2ncommon: (tomj) added daemon handling and recursive_delete()

[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.hxx"

using namespace std;

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

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

/**
 * Lookup uid for given username
 * @param username username to convert
 * @return uid of the user
 */
uid_t daemon::lookup_uid(const std::string &username)
{
    struct passwd *user = getpwnam(username.c_str());
    if (user == NULL) {
        throw runtime_error("user " + username + " not found");
    }

    return user->pw_uid;
}

/**
 * Lookup gid for given group
 * @param group group to convert
 * @return gid of the group
 */
gid_t daemon::lookup_gid(const std::string &group)
{
    struct group *my_group = getgrnam(group.c_str());
    if (my_group == NULL) {
        throw runtime_error("group " + group + " not found");
    }

    return my_group->gr_gid;
}

/**
 * Drop root priviledges
 * @param username User to become. Don't change user if empty
 * @param group Group to become. Don't change group if empty
 */
void daemon::drop_root_priviledges(const std::string &username,
                                                 const std::string &group)
{
    if (!group.empty()) {
        if (setgid(daemon::lookup_gid(group))) {
            throw runtime_error("Can't change to group " + group);
        }
    }

    if (!username.empty()) {
        if (setuid(daemon::lookup_uid(username))) {
            throw runtime_error("Can't change to user " + username);
        }
    }
}