# HG changeset patch
# User Pulkit Goyal <7895pulkit@gmail.com>
# Date 1602061007 -19800
# Node ID 225e513c444ef742c16e7436936ed8854e9d23cf
# Parent  37c65704869d33223d1e2f750a95308914993ccc
tags: add safety check for len(record) while reading hgtagsfnodescache

I am trying to fix a breakage where somehow we end up getting a node of 12
length from `getfnode()`. Understanding the hgtagsfnodescache code, it seems
highly unlikely that it can happen unless one of `mctx.readfast().get()` or
`ctx.filenode()` is returning a node of 12 length.

For safety, I think it's better to add a check to make sure that record which we
are parsing is of same length we are expecting otherwise we consider that as
invalid record.

Differential Revision: https://phab.mercurial-scm.org/D9169

diff -r 37c65704869d -r 225e513c444e mercurial/tags.py
--- a/mercurial/tags.py	Wed Oct 14 17:52:18 2020 +0200
+++ b/mercurial/tags.py	Wed Oct 07 14:26:47 2020 +0530
@@ -759,7 +759,7 @@
         properprefix = node[0:4]
 
         # Validate and return existing entry.
-        if record != _fnodesmissingrec:
+        if record != _fnodesmissingrec and len(record) == _fnodesrecsize:
             fileprefix = record[0:4]
 
             if fileprefix == properprefix: