From faad7a3ed19ad5bc604c48123583634234479c93 Mon Sep 17 00:00:00 2001
From: Conor Byrne <71222289+cbyrneee@users.noreply.github.com>
Date: Thu, 30 Dec 2021 16:41:29 +0000
Subject: [PATCH] LibDiff: Fix error when parsing a 'new' hunk location

If the location started at 0, and / or the length was 0, it would
originally turn out to be a location of { -1, -1 } when LibDiff was
finished parsing, which was incorrect.

To fix this, we only subtract 1 if `start` or `length` isn't 0.
---
 Userland/Libraries/LibDiff/Hunks.cpp | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/Userland/Libraries/LibDiff/Hunks.cpp b/Userland/Libraries/LibDiff/Hunks.cpp
index 6870dda028..fe526045aa 100644
--- a/Userland/Libraries/LibDiff/Hunks.cpp
+++ b/Userland/Libraries/LibDiff/Hunks.cpp
@@ -83,10 +83,16 @@ HunkLocation parse_hunk_location(const String& location_line)
     };
     auto parse_start_and_length_pair = [](const String& raw) {
         auto index_of_separator = raw.find(',').value();
-        auto start = raw.substring(0, index_of_separator);
-        auto length = raw.substring(index_of_separator + 1, raw.length() - index_of_separator - 1);
-        auto res = StartAndLength { start.to_uint().value() - 1, length.to_uint().value() - 1 };
-        return res;
+        auto start = raw.substring(0, index_of_separator).to_uint().value();
+        auto length = raw.substring(index_of_separator + 1, raw.length() - index_of_separator - 1).to_uint().value();
+
+        if (start != 0)
+            start--;
+
+        if (length != 0)
+            length--;
+
+        return StartAndLength { start, length };
     };
     while (char_index < location_line.length() && location_line[char_index++] != '-') {
     }