From: Simon Tatham <anakin@pobox.com>
Date: Mon, 2 Oct 2000 11:47:30 +0000 (+0000)
Subject: Deletion case 2c can shift the root; case 3b is not the only case that
X-Git-Tag: 0.50~48
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=4a2ea18a51a065539e55462c34445cea3e389283;p=PuTTY.git

Deletion case 2c can shift the root; case 3b is not the only case that
can do that. The bad case happens when you have a root node containing
only one actual element, and its two child nodes have only one element
each, and you try to delete the element in the root.

[originally from svn r660]
---

diff --git a/tree234.c b/tree234.c
index 8101c78b..f97837a1 100644
--- a/tree234.c
+++ b/tree234.c
@@ -569,6 +569,17 @@ void del234(tree234 *t, void *e) {
 	    }
 	    n->elems[j] = NULL;
 	    n->kids[j+1] = NULL;
+            /*
+             * It's possible, in this case, that we've just removed
+             * the only element in the root of the tree. If so,
+             * shift the root.
+             */
+            if (n->elems[0] == NULL) {
+                LOG(("  shifting root!\n"));
+                t->root = a;
+                a->parent = NULL;
+                sfree(n);
+            }
 	    /*
 	     * Now go round the deletion process again, with n
 	     * pointing at the new big node and e still the same.