/* Copyright (C) 1989, 1991-2018 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 <assert.h>

#include <errno.h>

#include <grp.h>

#include <limits.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/param.h>

#include <sys/types.h>

#include <nsswitch.h>

#include <scratch_buffer.h>

#include <config.h>

#include "../nscd/nscd-client.h"

#include "../nscd/nscd_proto.h"

#ifdef LINK_OBSOLETE_NSL

# define DEFAULT_CONFIG "compat [NOTFOUND=return] files"

#else

# define DEFAULT_CONFIG "files"

#endif

/* Type of the lookup function.  */

typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,

						    long int *, long int *,

						    gid_t **, long int, int *);

static bool use_initgroups_entry;

#include "compat-initgroups.c"

static int

internal_getgrouplist (const char *user, gid_t group, long int *size,

		       gid_t **groupsp, long int limit)

{

#ifdef USE_NSCD

  if (__nss_not_use_nscd_group > 0

      && ++__nss_not_use_nscd_group > NSS_NSCD_RETRY)

    __nss_not_use_nscd_group = 0;

  if (!__nss_not_use_nscd_group

      && !__nss_database_custom[NSS_DBSIDX_group])

    {

      int n = __nscd_getgrouplist (user, group, size, groupsp, limit);

      if (n >= 0)

	return n;

      /* nscd is not usable.  */

      __nss_not_use_nscd_group = 1;

    }

#endif

  enum nss_status status = NSS_STATUS_UNAVAIL;

  int no_more = 0;

  /* Never store more than the starting *SIZE number of elements.  */

  assert (*size > 0);

  (*groupsp)[0] = group;

  /* Start is one, because we have the first group as parameter.  */

  long int start = 1;

  if (__nss_initgroups_database == NULL)

    {

      if (__nss_database_lookup ("initgroups", NULL, "",

				 &__nss_initgroups_database) < 0)

	{

	  if (__nss_group_database == NULL)

	    no_more = __nss_database_lookup ("group", NULL, DEFAULT_CONFIG,

					     &__nss_group_database);

	  __nss_initgroups_database = __nss_group_database;

	}

      else

	use_initgroups_entry = true;

    }

  else

    /* __nss_initgroups_database might have been set through

       __nss_configure_lookup in which case use_initgroups_entry was

       not set here.  */

    use_initgroups_entry = __nss_initgroups_database != __nss_group_database;

  service_user *nip = __nss_initgroups_database;

  while (! no_more)

    {

      long int prev_start = start;

      initgroups_dyn_function fct = __nss_lookup_function (nip,

							   "initgroups_dyn");

      if (fct == NULL)

	status = compat_call (nip, user, group, &start, size, groupsp,

			      limit, &errno);

      else

	status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,

				    limit, &errno));

      /* Remove duplicates.  */

      long int cnt = prev_start;

      while (cnt < start)

	{

	  long int inner;

	  for (inner = 0; inner < prev_start; ++inner)

	    if ((*groupsp)[inner] == (*groupsp)[cnt])

	      break;

	  if (inner < prev_start)

	    (*groupsp)[cnt] = (*groupsp)[--start];

	  else

	    ++cnt;

	}

      /* This is really only for debugging.  */

      if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)

	__libc_fatal ("illegal status in internal_getgrouplist");

      /* For compatibility reason we will continue to look for more

	 entries using the next service even though data has already

	 been found if the nsswitch.conf file contained only a 'groups'

	 line and no 'initgroups' line.  If the latter is available

	 we always respect the status.  This means that the default

	 for successful lookups is to return.  */

      if ((use_initgroups_entry || status != NSS_STATUS_SUCCESS)

	  && nss_next_action (nip, status) == NSS_ACTION_RETURN)

	 break;

      if (nip->next == NULL)

	no_more = -1;

      else

	nip = nip->next;

    }

  return start;

}

/* Store at most *NGROUPS members of the group set for USER into

   *GROUPS.  Also include GROUP.  The actual number of groups found is

   returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.  */

int

getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)

{

  long int size = MAX (1, *ngroups);

  gid_t *newgroups = (gid_t *) malloc (size * sizeof (gid_t));

  if (__glibc_unlikely (newgroups == NULL))

    /* No more memory.  */

    // XXX This is wrong.  The user provided memory, we have to use

    // XXX it.  The internal functions must be called with the user

    // XXX provided buffer and not try to increase the size if it is

    // XXX too small.  For initgroups a flag could say: increase size.

    return -1;

  int total = internal_getgrouplist (user, group, &size, &newgroups, -1);

  memcpy (groups, newgroups, MIN (*ngroups, total) * sizeof (gid_t));

  free (newgroups);

  int retval = total > *ngroups ? -1 : total;

  *ngroups = total;

  return retval;

}

nss_interface_function (getgrouplist)

/* Initialize the group set for the current user

   by reading the group database and using all groups

   of which USER is a member.  Also include GROUP.  */

int

initgroups (const char *user, gid_t group)

{

#if defined NGROUPS_MAX && NGROUPS_MAX == 0

  /* No extra groups allowed.  */

  return 0;

#else

  long int size;

  gid_t *groups;

  int ngroups;

  int result;

 /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the

     limit can be raised in the kernel configuration without having to

     recompile libc.  */

  long int limit = __sysconf (_SC_NGROUPS_MAX);

  if (limit > 0)

    /* We limit the size of the intially allocated array.  */

    size = MIN (limit, 64);

  else

    /* No fixed limit on groups.  Pick a starting buffer size.  */

    size = 16;

  groups = (gid_t *) malloc (size * sizeof (gid_t));

  if (__glibc_unlikely (groups == NULL))

    /* No more memory.  */

    return -1;

  ngroups = internal_getgrouplist (user, group, &size, &groups, limit);

  /* Try to set the maximum number of groups the kernel can handle.  */

  do

    result = setgroups (ngroups, groups);

  while (result == -1 && errno == EINVAL && --ngroups > 0);

  free (groups);

  return result;

#endif

}

nss_interface_function (initgroups)