X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/b817bfc642225b8c3c0b6a7e42d1fb949b61a606..cd6eca4375f46a35b93e2fea4b0428a23b451aa3:/share.c

diff --git a/share.c b/share.c
index 23d730c..1afa189 100644
--- a/share.c
+++ b/share.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: share.c,v 1.7 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
  *
  * Shamir's secret sharing
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,12 +15,12 @@
  * 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.
- * 
+ *
  * Catacomb 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 Catacomb; if not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
@@ -172,6 +172,26 @@ mp *share_get(share *s, mp *d, unsigned x)
   return (d);
 }
 
+/* --- @share_addedp@ --- *
+ *
+ * Arguments:	@share *s@ = pointer to sharing context
+ *		@unsigned x@ = which share number to check
+ *
+ * Returns:	Nonzero if share @x@ has been added already, zero if it
+ *		hasn't.
+ */
+
+int share_addedp(share *s, unsigned x)
+{
+  unsigned i;
+
+  for (i = 0; i < s->i; i++) {
+    if (s->v[i].x == x + 1)
+      return (1);
+  }
+  return (0);
+}
+
 /* --- @share_add@ --- *
  *
  * Arguments:	@share *s@ = pointer to sharing context
@@ -186,6 +206,9 @@ mp *share_get(share *s, mp *d, unsigned x)
 
 unsigned share_add(share *s, unsigned x, mp *y)
 {
+  assert(((void)"Share context is full", s->i < s->t));
+  assert(((void)"Share already present", !share_addedp(s, x)));
+
   /* --- If no vector has been allocated, create one --- */
 
   if (!s->v) {
@@ -196,8 +219,6 @@ unsigned share_add(share *s, unsigned x, mp *y)
       s->v[i].y = 0;
   }
 
-  assert(((void)"Share context is full", s->i < s->t));
-
   /* --- Store the share in the vector --- */
 
   s->v[s->i].x = x + 1;