Initial checkin

1 files changed, 130 insertions, 0 deletions

diff --git a/libshouldbeinlibc/ugids-subtract.c b/libshouldbeinlibc/ugids-subtract.c
new file mode 100644
index 00000000..eecba20e
--- /dev/null
+++ b/libshouldbeinlibc/ugids-subtract.c
@@ -0,0 +1,130 @@
+/* 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 <stdlib.h>
+#include <stdio.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;
+}