From 25075c27222e3ce58d6c352d9e5ecf2e9705b153 Mon Sep 17 00:00:00 2001
From: Adam Johnson <AdamJohnso@gmail.com>
Date: Sun, 30 Aug 2020 04:58:02 -0400
Subject: [PATCH] Fix round-tripping plPythonFileMod through HSPlasma.

This fixes an issue in which PythonFileMods with string parameters would
be shattered by round-tripping through HSPlasma. The spurious null
terminator was being accumulated into the parameter, causing two nulls
to be serialized. This caused a null byte to be passed to CWE's Python,
resulting in a difficult to debug scenario where we had a seemingly
valid string object in Python but the validation in `PyArg_ParseTuple`
failed.
---
 core/PRP/Modifier/plPythonFileMod.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/core/PRP/Modifier/plPythonFileMod.cpp b/core/PRP/Modifier/plPythonFileMod.cpp
index 2e7437056..de5f06584 100644
--- a/core/PRP/Modifier/plPythonFileMod.cpp
+++ b/core/PRP/Modifier/plPythonFileMod.cpp
@@ -82,10 +82,11 @@ void plPythonParameter::read(hsStream* S, plResManager* mgr)
     case kSubtitle:
         size = S->readInt();
         if (size == 0) {
-            fStrValue = "";
+            fStrValue = ST::null;
             return;
         }
-        fStrValue = S->readStr(size);
+        fStrValue = S->readStr(size - 1);
+        S->readByte();
         return;
     case kNone:
         return;