From 060836c1330dc91bed9e405cf6e80bea49f77843 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 19 Sep 2012 17:43:15 +0530
Subject: [PATCH] AZW3 Output: Do not error out if the input document contains
 embedded fonts of less than 1040 bytes. Fixes #1052892 (conversion error -
 epub to azw3 - bytearray index out of range)

---
 src/calibre/ebooks/mobi/utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/ebooks/mobi/utils.py b/src/calibre/ebooks/mobi/utils.py
index ae8e583a1b..09e3055a6e 100644
--- a/src/calibre/ebooks/mobi/utils.py
+++ b/src/calibre/ebooks/mobi/utils.py
@@ -481,7 +481,7 @@ def write_font_record(data, obfuscate=True, compress=True):
     if compress:
         flags |= 0b1
         data = zlib.compress(data, 9)
-    if obfuscate:
+    if obfuscate and len(data) >= 1040:
         flags |= 0b10
         xor_key = os.urandom(key_len)
         key = bytearray(xor_key)