From 7adfa44e02041a6d9b571025a8237a13fa6fbde8 Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Thu, 22 Dec 2016 17:22:44 -0800
Subject: [PATCH] Fix freelist.size calculation for large freelists

freelist.size did not account for the extra
fake freelist item used to hold the number of
elements when the freelist is large.
---
 freelist.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/freelist.go b/freelist.go
index de59aaa..aba48f5 100644
--- a/freelist.go
+++ b/freelist.go
@@ -24,7 +24,12 @@ func newFreelist() *freelist {
 
 // size returns the size of the page after serialization.
 func (f *freelist) size() int {
-	return pageHeaderSize + (int(unsafe.Sizeof(pgid(0))) * f.count())
+	n := f.count()
+	if n >= 0xFFFF {
+		// The first element will be used to store the count. See freelist.write.
+		n++
+	}
+	return pageHeaderSize + (int(unsafe.Sizeof(pgid(0))) * n)
 }
 
 // count returns count of pages on the freelist