From e877a2a54634e0f3cf7d57cc95a1f8a486ae476f Mon Sep 17 00:00:00 2001
From: Sina Hinderks <sina@hinderks.net>
Date: Sat, 20 Dec 2025 02:40:15 +0100
Subject: [PATCH] fix: stage/discard/unstage hunk

There is a regression bug regarding staging, discarding, and unstaging
hunks.  Depending on the data, these actions may be ignored or only
partially executed.

The following script generates a repository in the current directory
(named after the current directory) with four examples.  Save the script
as `create-hunk-regression.sh`, make it executable with `chmod +x
create-hunk-regression.sh`, and start it with
`./create-hunk-regression.sh`.  (Tested on Linux, should also work on
Windows.)

```bash
#!/usr/bin/env bash

set -e

dir=$(basename $(pwd))

rm -rf "$dir"
git init -b main "$dir" && cd "$dir"

echo -n '1n2n3n4n' | tr 'rn' '\r\n' > cannot-stage-hunks.txt
echo -n '2rn3rn' | tr 'rn' '\r\n' > partially-stages-hunks.txt
echo -n 'test1rnrnrnrntest3rn' | tr 'rn' '\r\n' > partially-stages-or-discards-hunk.txt

echo -n '1rn2rn3rn4rn' | tr 'rn' '\r\n' > cannot-unstage-hunks.txt

git add .
git commit -m 'initial commit'

echo -n '1rn2n3n4rn' | tr 'rn' '\r\n' > cannot-stage-hunks.txt
echo -n '1rn2rn3rn4rn' | tr 'rn' '\r\n' > partially-stages-hunks.txt
echo -n 'test1rnrntest2rnrntest3rn' | tr 'rn' '\r\n' > partially-stages-or-discards-hunk.txt

echo -n '1n2rn3rn4n' | tr 'rn' '\r\n' > cannot-unstage-hunks.txt

git add cannot-unstage-hunks.txt
```

For the examples to fully work you should configure Git/SourceGit the
following way:

  - set `core.autocrlf` to `false`
  - do not enable `--ignore-cr-at-eol` in diff
  - do not ignore wwhitespace changes

This regression was introduced in commit 5c9d96, where breaking up the
diff into lines was changed from explicitly doing it to using the stream
function `ReadLineAsync`.  Whereas the explicit code handled CR and LF
correctly, the stream function handles CR, CR/LF and LF the same way, so
that for Windows newlines (CR/LF) the CR will be lost.

The fix for this regression is going back to the explicit code and
ignoring `ReadLineAsync` for reading diffs.

This should fix at least partially issues #1950 and #1995.
---
 src/Commands/Diff.cs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/Commands/Diff.cs b/src/Commands/Diff.cs
index 3fdc62259..680aff63d 100644
--- a/src/Commands/Diff.cs
+++ b/src/Commands/Diff.cs
@@ -46,9 +46,22 @@ public Diff(string repo, Models.DiffOption opt, int unified, bool ignoreWhitespa
                 proc.StartInfo = CreateGitStartInfo(true);
                 proc.Start();
 
-                while (await proc.StandardOutput.ReadLineAsync().ConfigureAwait(false) is { } line)
+                var text = await proc.StandardOutput.ReadToEndAsync().ConfigureAwait(false);
+
+                var start = 0;
+                var end = text.IndexOf('\n', start);
+                while (end > 0)
+                {
+                    var line = text[start..end];
                     ParseLine(line);
 
+                    start = end + 1;
+                    end = text.IndexOf('\n', start);
+                }
+
+                if (start < text.Length)
+                    ParseLine(text[start..]);
+
                 await proc.WaitForExitAsync().ConfigureAwait(false);
             }
             catch