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/* Subtract one set of user and group ids from another
Copyright (C) 1997 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
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, 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. */
#include <errno.h>
#include "idvec.h"
#include "ugids.h"
/* Remove the gids in SUB from those in GIDS, except where they are implied
in SUB (as represented by SUB_IMP), but not in GIDS (as represented by
GIDS_IMP). */
static
error_t _sub_gids (struct idvec *gids, struct idvec *gids_imp,
const struct idvec *sub, const struct idvec *sub_imp)
{
error_t err;
/* What we'll remove from GIDS. */
struct idvec delta = IDVEC_INIT;
/* Those implied ids in SUB that we *won't* remove, because they're not
also implied in GIDS. */
struct idvec delta_suppress = IDVEC_INIT;
err = idvec_set (&delta, sub);
if (! err)
err = idvec_set (&delta_suppress, sub_imp);
if (! err)
{
/* Don't suppress those implied ids that are implied in both. */
idvec_subtract (&delta_suppress, gids_imp);
idvec_subtract (&delta, &delta_suppress);
/* Actually remove the gids. */
idvec_subtract (gids, &delta);
}
idvec_fini (&delta);
idvec_fini (&delta_suppress);
return err;
}
/* Remove the in SUB from those in GIDS, except where they are implied
in SUB (as represented by SUB_IMP), but not in GIDS (as represented by
GIDS_IMP). */
static
error_t _sub (struct idvec *uids, struct idvec *gids, struct idvec *gids_imp,
const struct idvec *sub_uids,
const struct idvec *sub_gids, const struct idvec *sub_gids_imp)
{
error_t err;
struct idvec new_uids = IDVEC_INIT; /* The set of uids after subtraction. */
struct idvec no_sub_gids = IDVEC_INIT; /* Gids we *don't* want to remove
from GIDS, despite what's in
SUB_GIDS. */
struct idvec new_sub_gids = IDVEC_INIT;
struct idvec new_sub_gids_imp = IDVEC_INIT;
err = idvec_set (&new_uids, uids);
if (! err)
err = idvec_set (&new_sub_gids, sub_gids);
if (! err)
err = idvec_set (&new_sub_gids_imp, sub_gids_imp);
if (! err)
{
idvec_subtract (&new_uids, sub_uids);
err = idvec_merge_implied_gids (&no_sub_gids, &new_uids);
if (! err)
{
/* NO_SUB_GIDS is the intersection of implied gids in GIDS,
implied gids in SUB_GIDS, and implied gids after the subtraction
of uids -- we don't want to remove those implied gids because we
can't be sure which uids implied them (as there will be
appropriately implicative uids left after the subtraction). */
idvec_keep (&no_sub_gids, gids_imp);
idvec_keep (&no_sub_gids, sub_gids_imp);
/* Remove those gids we don't want to subtract. */
idvec_subtract (&new_sub_gids, &no_sub_gids);
idvec_subtract (&new_sub_gids_imp, &no_sub_gids);
/* Do the group subtraction. */
err = _sub_gids (gids, gids_imp, &new_sub_gids, &new_sub_gids_imp);
if (! err)
/* Finally, if no problems, do the uid subtraction. */
err = idvec_set (uids, &new_uids);
}
}
idvec_fini (&new_uids);
idvec_fini (&no_sub_gids);
idvec_fini (&new_sub_gids);
idvec_fini (&new_sub_gids_imp);
return err;
}
/* Remove the ids in SUB from those in UGIDS. */
error_t
ugids_subtract (struct ugids *ugids, const struct ugids *sub)
{
error_t err =
_sub (&ugids->eff_uids, &ugids->eff_gids, &ugids->imp_eff_gids,
&sub->eff_uids, &sub->eff_gids, &sub->imp_eff_gids);
if (! err)
/* If this second call to _sub fails, ugids will be in an inconsistent
state, but oh well. */
err = _sub (&ugids->avail_uids, &ugids->avail_gids, &ugids->imp_avail_gids,
&sub->avail_uids, &sub->avail_gids, &sub->imp_avail_gids);
return err;
}
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