/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <ctype.h>

#include <errno.h>

#include <stdio.h>

#include <stdio_ext.h>

#include <stdlib.h>

#include <string.h>

#include <libc-lock.h>

#include <libnsl.h>

/* Path of the file.  */

static const char default_nss[] = "/etc/default/nss";

/* Flags once read from the file.  */

static int default_nss_flags;

/* Code to make sure we call 'init' once.  */

__libc_once_define (static, once);

/* Table of the recognized variables.  */

static const struct

{

  char name[23];

  unsigned int len;

  int flag;

} vars[] =

  {

#define STRNLEN(s) s, sizeof (s) - 1

    { STRNLEN ("NETID_AUTHORITATIVE"), NSS_FLAG_NETID_AUTHORITATIVE },

    { STRNLEN ("SERVICES_AUTHORITATIVE"), NSS_FLAG_SERVICES_AUTHORITATIVE },

    { STRNLEN ("SETENT_BATCH_READ"), NSS_FLAG_SETENT_BATCH_READ },

    { STRNLEN ("ADJUNCT_AS_SHADOW"), NSS_FLAG_ADJUNCT_AS_SHADOW },

  };

#define nvars (sizeof (vars) / sizeof (vars[0]))

static void

init (void)

{

  int saved_errno = errno;

  FILE *fp = fopen (default_nss, "rce");

  if (fp != NULL)

    {

      char *line = NULL;

      size_t linelen = 0;

      __fsetlocking (fp, FSETLOCKING_BYCALLER);

      while (!feof_unlocked (fp))

	{

	  ssize_t n = getline (&line, &linelen, fp);

	  if (n <= 0)

	    break;

	  /* Recognize only

	       <THE-VARIABLE> = TRUE

	     with arbitrary white spaces.  */

	  char *cp = line;

	  while (isspace (*cp))

	    ++cp;

	  /* Recognize comment lines.  */

	  if (*cp == '#')

	    continue;

	  int idx;

	  for (idx = 0; idx < nvars; ++idx)

	    if (strncmp (cp, vars[idx].name, vars[idx].len) == 0)

	      break;

	  if (idx == nvars)

	    continue;

	  cp += vars[idx].len;

	  while (isspace (*cp))

	    ++cp;

	  if (*cp++ != '=')

	    continue;

	  while (isspace (*cp))

	    ++cp;

	  if (strncmp (cp, "TRUE", 4) != 0)

	    continue;

	  cp += 4;

	  while (isspace (*cp))

	    ++cp;

	  if (*cp == '\0')

	    default_nss_flags |= vars[idx].flag;

	}

      free (line);

      fclose (fp);

    }

  __set_errno (saved_errno);

}

int

_nsl_default_nss (void)

{

  /* If we have not yet read the file yet do it now.  */

  __libc_once (once, init);

  return default_nss_flags;

}