path: root/nss/nsswitch.c

/* Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <ctype.h>
#include <dlfcn.h>
#include <errno.h>
#include <netdb.h>
#include <bits/libc-lock.h>
#include <link.h>	/* We need some help from ld.so.  */
#include <search.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if !defined DO_STATIC_NSS || defined PIC
# include <gnu/lib-names.h>
#endif

#include "nsswitch.h"

/* Prototypes for the local functions.  */
static void *nss_lookup_function (service_user *ni, const char *fct_name)
     internal_function;
static name_database *nss_parse_file (const char *fname) internal_function;
static name_database_entry *nss_getline (char *line) internal_function;
static service_user *nss_parse_service_list (const char *line)
     internal_function;
static service_library *nss_new_service (name_database *database,
					 const char *name) internal_function;


/* Declare external database variables.  */
#define DEFINE_DATABASE(name)						      \
  extern service_user *__nss_##name##_database;				      \
  weak_extern (__nss_##name##_database)
#include "databases.def"
#undef DEFINE_DATABASE

/* Structure to map database name to variable.  */
static struct
{
  const char *name;
  service_user **dbp;
} databases[] =
{
#define DEFINE_DATABASE(name)						      \
  { #name, &__nss_##name##_database },
#include "databases.def"
#undef DEFINE_DATABASE
};


__libc_lock_define_initialized (static, lock)

#if !defined DO_STATIC_NSS || defined PIC
/* String with revision number of the shared object files.  */
static const char *const __nss_shlib_revision = LIBNSS_FILES_SO + 15;
#endif

/* The root of the whole data base.  */
static name_database *service_table;


/* -1 == database not found
    0 == database entry pointer stored */
int
__nss_database_lookup (const char *database, const char *alternate_name,
		       const char *defconfig, service_user **ni)
{
  /* Prevent multiple threads to change the service table.  */
  __libc_lock_lock (lock);

  /* Reconsider database variable in case some other thread called
     `__nss_configure_lookup' while we waited for the lock.  */
  if (*ni != NULL)
    {
      __libc_lock_unlock (lock);
      return 0;
    }

  /* Are we initialized yet?  */
  if (service_table == NULL)
    /* Read config file.  */
    service_table = nss_parse_file (_PATH_NSSWITCH_CONF