From 218610ea33ef22ec1836f4fd43c3223676de5e51 Mon Sep 17 00:00:00 2001
From: Victor Nova <lost@losttech.software>
Date: Fri, 28 Oct 2022 16:00:56 -0700
Subject: [PATCH] fixed positive PyInt converted to negative BigInteger

BigInteger constructor uses the sign bit in the first byte. Since we explicitly handle the sign, the fix is to prepend a zero byte to the number, which does not change it, but ensures sign bit is zero.

fixes https://github.com/pythonnet/pythonnet/issues/1990
---
 CHANGELOG.md                     |  1 +
 src/embed_tests/TestPyInt.cs     | 17 ++++++++++++-----
 src/runtime/PythonTypes/PyInt.cs |  2 +-
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9781f289c..71c36b412 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 ### Fixed
 
 -   Fixed objects leaking when Python attached event handlers to them even if they were later removed
+-   Fixed `PyInt` conversion to `BigInteger` and `System.String` produced incorrect result for values between 128 and 255.
 
 
 ## [3.0.0](https://github.com/pythonnet/pythonnet/releases/tag/v3.0.0) - 2022-09-29
diff --git a/src/embed_tests/TestPyInt.cs b/src/embed_tests/TestPyInt.cs
index 822fe0715..c147e074b 100644
--- a/src/embed_tests/TestPyInt.cs
+++ b/src/embed_tests/TestPyInt.cs
@@ -191,16 +191,23 @@ public void ToBigInteger()
             {
                 0, 1, 2,
                 0x10,
+                0x79,
+                0x80,
+                0x81,
+                0xFF,
                 0x123,
+                0x8000,
                 0x1234,
+                0x8001,
+                0x4000,
+                0xFF,
             };
             simpleValues = simpleValues.Concat(simpleValues.Select(v => -v)).ToArray();
 
-            foreach (var val in simpleValues)
-            {
-                var pyInt = new PyInt(val);
-                Assert.AreEqual((BigInteger)val, pyInt.ToBigInteger());
-            }
+            var expected = simpleValues.Select(v => new BigInteger(v)).ToArray();
+            var actual = simpleValues.Select(v => new PyInt(v).ToBigInteger()).ToArray();
+
+            CollectionAssert.AreEqual(expected, actual);
         }
 
         [Test]
diff --git a/src/runtime/PythonTypes/PyInt.cs b/src/runtime/PythonTypes/PyInt.cs
index 6b3dbf210..e71462b74 100644
--- a/src/runtime/PythonTypes/PyInt.cs
+++ b/src/runtime/PythonTypes/PyInt.cs
@@ -212,7 +212,7 @@ public BigInteger ToBigInteger()
                 offset++;
                 neg = true;
             }
-            byte[] littleEndianBytes = new byte[(hex.Length - offset + 1) / 2];
+            byte[] littleEndianBytes = new byte[(hex.Length - offset + 1) / 2 + 1];
             for (; offset < hex.Length; offset++)
             {
                 int littleEndianHexIndex = hex.Length - 1 - offset;