/*
 * Copyright (C) 2001  Hakan Tandogan (hakan@gurkensalat.com)
 *
 * 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.
 */

#include "common/setup_before.h"
#ifdef HAVE_STDDEF_H
# include <stddef.h>
#else
# ifndef NULL
#  define NULL ((void *)0)
# endif
#endif
#ifdef STDC_HEADERS
# include <stdlib.h>
#endif
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_PWD_H
# include <pwd.h>
#endif
#ifdef HAVE_GRP_H
# include <grp.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#include <errno.h>
#include "compat/strerror.h"
#include "common/eventlog.h"
#include "common/give_up_root_privileges.h"
#include "common/setup_after.h"


#define ILLEGAL_ID -1


static int gurp_gname2id(const char *name);
static int gurp_uname2id(const char *name);


extern int give_up_root_privileges(char const * user_name, char const * group_name)
{
    int user_id;
    int group_id;
    
    eventlog(eventlog_level_debug,"give_up_root_privileges","about to give up root privileges");
    
    if (user_name)
	if ((user_id = gurp_uname2id(user_name))==ILLEGAL_ID)
	    return -1;
        else
            eventlog(eventlog_level_debug,"give_up_root_privileges","should change to user = '%s' (%d)", user_name, user_id);
    if (group_name)
	if ((group_id = gurp_gname2id(group_name))==ILLEGAL_ID)
	    return -1;
        else
            eventlog(eventlog_level_debug,"give_up_root_privileges","should change to group = '%s' (%d)", group_name, group_id);
    
    /*  Change first the group ID, later we might not be able to anymore
     *  We can use setgid safely because we don't want to return to root
     *  privileges anymore
     */
    
#ifdef HAVE_SETGID
    if (user_name)
    {
        if (-1 == setgid(group_id))
        {
            eventlog(eventlog_level_fatal,"give_up_root_privileges","could not set gid to %d (setgid: %s)", group_id, strerror(errno));
            return -1;
        }    
# ifdef HAVE_GETUID
        eventlog(eventlog_level_info,"give_up_root_privileges","Changed privileges to gid = %d", getgid());
# endif
    }
#endif
    
#ifdef HAVE_SETUID
    if (group_name)
    {
        if (-1 == setuid(user_id))
        {
            eventlog(eventlog_level_fatal,"give_up_root_privileges","could not set uid to %d (setuid: %s)", user_id, strerror(errno));
            return -1;
        }    
# ifdef HAVE_GETGID
        eventlog(eventlog_level_info,"give_up_root_privileges","Changed privileges to uid = %d", getuid());
# endif
    }
#endif
    
    return 0;
}


static int gurp_uname2id(const char *name)
{
    int id = ILLEGAL_ID;
    
    if (name != NULL)
    {
        if (name[0] == '#')
        {
            id = atoi(&name[1]);
        }
        else
        {
#ifdef HAVE_GETPWNAM
            struct passwd * ent;
            
            eventlog(eventlog_level_debug,"give_up_root_privileges","about to getpwnam(%s)", name);
            
            if (!(ent = getpwnam(name)))
            {
                eventlog(eventlog_level_fatal,"give_up_root_privileges","cannot get password file entry for '%s' (getpwnam: %s)", name, strerror(errno));
                return id;
            }
            id = ent->pw_uid;
#else
            return id;
#endif
        }
    }

    return id;
}


static int gurp_gname2id(const char *name)
{
    int id = ILLEGAL_ID;
    
    if (name != NULL)
    {
        if (name[0] == '#')
        {
            id = atoi(&name[1]);
        }
        else
        {
#ifdef HAVE_GETGRNAM
            struct group * ent;
            
            eventlog(eventlog_level_debug,"give_up_root_privileges","about to getgrnam(%s)", name);
            
            if (!(ent = getgrnam(name)))
            {
                eventlog(eventlog_level_fatal,"give_up_root_privileges","cannot get group file entry for '%s' (getgrnam: %s)", name, strerror(errno));
                return id;
            }
            id = ent->gr_gid;
#else
            return id;
#endif
        }
    }

    return id;
}