From 5b7f93bb9a5320201785cd0cb78dc7fe3afbb989 Mon Sep 17 00:00:00 2001
From: Johannes 'josch' Schauer <josch@mister-muffin.de>
Date: Mon, 3 Aug 2020 12:25:14 +0200
Subject: [PATCH] do not allow negative values in parse_num()

---
 src/img2pdf.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/img2pdf.py b/src/img2pdf.py
index b9dd1fd..e944d99 100755
--- a/src/img2pdf.py
+++ b/src/img2pdf.py
@@ -2083,6 +2083,9 @@ def parse_num(num, name):
         except ValueError:
             msg = "%s is not a floating point number: %s" % (name, num)
             raise argparse.ArgumentTypeError(msg)
+    if num < 0:
+        msg = "%s must not be negative: %s" % (name, num)
+        raise argparse.ArgumentTypeError(msg)
     if unit == Unit.cm:
         num = cm_to_pt(num)
     elif unit == Unit.mm: