suid.c

/*
 * hfsutils - tools for reading and writing Macintosh HFS volumes
 * Copyright (C) 1996-1998 Robert Leslie
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id: suid.c,v 1.7 1998/04/11 08:27:00 rob Exp $
 */

# ifdef HAVE_CONFIG_H
#  include "config.h"
# endif

# include <sys/types.h>

# ifdef HAVE_UNISTD_H
#  include <unistd.h>
# else
uid_t getuid(void);
uid_t geteuid(void);
gid_t getgid(void);
gid_t getegid(void);
#  ifdef HAVE_SETREUID
int setreuid(uid_t, uid_t);
int setregid(gid_t, gid_t);
#  else
int setuid(uid_t);
int setgid(gid_t);
#  endif
# endif

# include "suid.h"

static uid_t uid, euid;
static gid_t gid, egid;

/*
 * NAME:	suid->init()
 * DESCRIPTION:	initialize application which may be running setuid/setgid
 */
void suid_init(void)
{
  uid  = getuid();
  gid  = getgid();

  euid = geteuid();
  egid = getegid();

  suid_disable();
}

/*
 * NAME:	suid->enable()
 * DESCRIPTION:	engage any setuid privileges
 */
void suid_enable(void)
{
# ifdef HAVE_SETREUID

  setreuid(-1, euid);
  setregid(-1, egid);

# else

  setuid(euid);
  setgid(egid);

# endif
}

/*
 * NAME:	suid->disable()
 * DESCRIPTION:	revoke all setuid privileges
 */
void suid_disable(void)
{
# ifdef HAVE_SETREUID

  setreuid(-1, uid);
  setregid(-1, gid);

# else

  setuid(uid);
  setgid(gid);

# endif
}