/* Quintuple Agent
 * Copyright (C) 1999 Robert Bihlmeyer <robbe@orcus.priv.at>
 *
 *  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.
 */

#define _GNU_SOURCE 1

#include <unistd.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

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

#include "i18n.h"
#include "util.h"

#ifndef TEMP_FAILURE_RETRY
#define TEMP_FAILURE_RETRY(expression) \
  (__extension__							      \
    ({ long int __result;						      \
       do __result = (long int) (expression);				      \
       while (__result == -1L && errno == EINTR);			      \
       __result; }))
#endif

static int uid_set = 0;
static uid_t real_uid, file_uid;

/* write DATA of size BYTES to FD, until all is written or an error occurs */
ssize_t xwrite(int fd, const void *data, size_t bytes)
{
  char *ptr;
  size_t todo;
  ssize_t written = 0;

  for (ptr = (char *)data, todo = bytes; todo; ptr += written, todo -= written)
    if ((written = TEMP_FAILURE_RETRY(write(fd, ptr, todo))) < 0)
      break;
  return written;
}

extern int debug;

int debugmsg(const char *fmt, ...)
{
  va_list va;
  int ret;

  if (debug) {
    va_start(va, fmt);
    fprintf(stderr, "\e[4m");
    ret = vfprintf(stderr, fmt, va);
    fprintf(stderr, "\e[24m");
    va_end(va);
    return ret;
  } else
    return 0;
}

/* wipe out a block of N bytes starting at address PTR */
void wipe(void *ptr, size_t n)
{
  /* you may want to overwrite with several different bit patterns, depending
     on your belief system. */
  memset(ptr, n, 0);
}

/* initialize uid variables */
static void init_uids()
{
  real_uid = getuid();
  file_uid = geteuid();
  uid_set = 1;
}

/* lower privileges to the real user's */
void lower_privs()
{
  if (!uid_set)
    init_uids();
  if (real_uid != file_uid) {
#ifdef HAVE_SETEUID
    if (seteuid(real_uid) < 0) {
      perror(_("lowering privileges failed"));
      exit(EXIT_FAILURE);
    }
#else
    fprintf(stderr, _("Warning: running q-agent setuid on this system is dangerous\n"));
#endif /* HAVE_SETEUID */
  }
}

/* raise privileges to the effective user's */
void raise_privs()
{
  assert(real_uid >= 0);	/* lower_privs() must be called before this */
#ifdef HAVE_SETEUID
  if (real_uid != file_uid && seteuid(file_uid) < 0) {
    perror(_("Warning: raising privileges failed"));
  }
#endif /* HAVE_SETEUID */
}

/* drop all additional privileges */
void drop_privs()
{
  if (!uid_set)
    init_uids();
  if (real_uid != file_uid) {
    if (setuid(real_uid) < 0) {
      perror(_("dropping privileges failed"));
      exit(EXIT_FAILURE);
    }
    file_uid = real_uid;
  }
}