From 95409884a16c6a8d1dc34c8c7c5c9392e525cc2f Mon Sep 17 00:00:00 2001
From: Kartik Subbarao <subbarao@computer.org>
Date: Sat, 15 Oct 2022 22:13:54 -0400
Subject: [PATCH] Fix tree_insert() duplicate detection logic, resolves
 MarcJHuber/event-driven-servers#11

---
 misc/rb.c | 44 +++++++++++++++++++++-----------------------
 1 file changed, 21 insertions(+), 23 deletions(-)

diff --git a/misc/rb.c b/misc/rb.c
index a3cd320..777db49 100644
--- a/misc/rb.c
+++ b/misc/rb.c
@@ -182,32 +182,30 @@ static void right_rotate(rb_tree_t * T, rb_node_t * x)
 
 static int tree_insert(rb_tree_t * T, rb_node_t * z)
 {
-    rb_node_t *x, *y;
-    y = rb_nil;
-    x = T->root;
-    while (x != rb_nil) {
-	y = x;
-	if (T->compare(z->payload, x->payload) < 0)
-	    x = x->left;
-	else
-	    x = x->right;
-    }
-    z->parent = y;
-    if (y == rb_nil)
-	T->root = z;
-    else {
-	int i = T->compare(z->payload, y->payload);
-	if (i < 0)
-	    y->left = z;
-	else if (i > 0)
-	    y->right = z;
-	else {
-	    return 0;		/* Duplicate! */
+	rb_node_t *x, *y;
+	y = rb_nil;
+	x = T->root;
+	while (x != rb_nil) {
+		y = x;
+		int i = T->compare(z->payload, x->payload);
+		if (i < 0)
+			x = x->left;
+		else if (i > 0)
+			x = x->right;
+		else {
 #ifdef DEBUG_RB
-	    fprintf(stderr, "dupe! %p\n", z->payload);
+			fprintf(stderr, "dupe! %p\n", z->payload);
 #endif
+			return 0;		/* Duplicate! */
+		}
 	}
-    }
+	z->parent = y;
+	if (y == rb_nil)
+		T->root = z;
+	else if (T->compare(z->payload, y->payload) < 0)
+		y->left = z;
+	else
+		y->right = z;
     z->prev = tree_predecessor(z);
     if (z->prev != rb_nil) {
 	z->next = z->prev->next;