From 27d9a805d9f884d8e30ca22c191dd70e0add82e1 Mon Sep 17 00:00:00 2001
From: a-kenji <aks.kenji@protonmail.com>
Date: Tue, 7 Oct 2025 09:16:22 +0200
Subject: [PATCH] WIP: Fix carriage return

---
 pkgs/clan-cli/clan_lib/cmd/__init__.py        | 28 +++++++--
 .../clan_lib/cmd/test_carriage_return.py      | 59 +++++++++++++++++++
 2 files changed, 83 insertions(+), 4 deletions(-)
 create mode 100644 pkgs/clan-cli/clan_lib/cmd/test_carriage_return.py

diff --git a/pkgs/clan-cli/clan_lib/cmd/__init__.py b/pkgs/clan-cli/clan_lib/cmd/__init__.py
index b730a34b4..c83e5ecad 100644
--- a/pkgs/clan-cli/clan_lib/cmd/__init__.py
+++ b/pkgs/clan-cli/clan_lib/cmd/__init__.py
@@ -126,9 +126,19 @@ def handle_io(
 
         # If Log.STDOUT is set, log the stdout output
         if ret and log in [Log.STDOUT, Log.BOTH]:
-            lines = ret.decode("utf-8", "replace").rstrip("\n").rstrip().split("\n")
+            decoded = ret.decode("utf-8", "replace").rstrip("\n").rstrip()
+            # Handle carriage returns: split by \r and only keep the last segment of each line
+            # This prevents progress indicators that use \r from creating multiple log lines
+            lines = []
+            for line in decoded.split("\n"):
+                if "\r" in line:
+                    # Only keep the last segment after the final \r (what would be visible)
+                    lines.append(line.split("\r")[-1])
+                else:
+                    lines.append(line)
             for line in lines:
-                cmdlog.info(line, extra=stdout_extra)
+                if line:  # Only log non-empty lines
+                    cmdlog.info(line, extra=stdout_extra)
 
         # If stdout file is set, stream the stdout output
         if ret and stdout:
@@ -143,9 +153,19 @@ def handle_io(
 
         # If Log.STDERR is set, log the stderr output
         if ret and log in [Log.STDERR, Log.BOTH]:
-            lines = ret.decode("utf-8", "replace").rstrip("\n").rstrip().split("\n")
+            decoded = ret.decode("utf-8", "replace").rstrip("\n").rstrip()
+            # Handle carriage returns: split by \r and only keep the last segment of each line
+            # This prevents progress indicators that use \r from creating multiple log lines
+            lines = []
+            for line in decoded.split("\n"):
+                if "\r" in line:
+                    # Only keep the last segment after the final \r (what would be visible)
+                    lines.append(line.split("\r")[-1])
+                else:
+                    lines.append(line)
             for line in lines:
-                cmdlog.info(line, extra=stderr_extra)
+                if line:  # Only log non-empty lines
+                    cmdlog.info(line, extra=stderr_extra)
 
         # If stderr file is set, stream the stderr output
         if ret and stderr:
diff --git a/pkgs/clan-cli/clan_lib/cmd/test_carriage_return.py b/pkgs/clan-cli/clan_lib/cmd/test_carriage_return.py
new file mode 100644
index 000000000..0f91f5cce
--- /dev/null
+++ b/pkgs/clan-cli/clan_lib/cmd/test_carriage_return.py
@@ -0,0 +1,59 @@
+import logging
+from pathlib import Path
+
+from clan_lib.cmd import Log, RunOpts, run
+
+
+def test_carriage_return_handling(caplog: logging.LogRecord) -> None:
+    """Test that carriage returns are handled properly to avoid duplicate progress lines."""
+    # Set logging to capture INFO level
+    caplog.set_level(logging.INFO)
+
+    # Run a command that simulates mkfs.ext4 progress output with carriage returns
+    result = run(
+        [
+            "bash",
+            "-c",
+            'printf "Progress: 1/5\\rProgress: 2/5\\rProgress: 3/5\\rProgress: 4/5\\rProgress: 5/5\\n"',
+        ],
+        RunOpts(log=Log.STDOUT, cwd=Path.cwd()),
+    )
+
+    # Check that the command succeeded
+    assert result.returncode == 0
+
+    # Check that only the final progress line was logged, not all intermediate ones
+    log_messages = [record.message for record in caplog.records]
+
+    # Should only see the final "Progress: 5/5" message, not all the intermediate ones
+    assert "Progress: 5/5" in log_messages
+    # Count how many "Progress:" messages there are - should be only 1
+    progress_messages = [msg for msg in log_messages if "Progress:" in msg]
+    assert len(progress_messages) == 1, f"Expected 1 progress message, got {len(progress_messages)}: {progress_messages}"
+
+
+def test_carriage_return_multiple_lines(caplog: logging.LogRecord) -> None:
+    """Test carriage returns on multiple separate lines."""
+    caplog.set_level(logging.INFO)
+
+    # Simulate multiple lines with progress indicators
+    result = run(
+        [
+            "bash",
+            "-c",
+            'printf "Line 1\\nProgress: 10%%\\rProgress: 50%%\\rProgress: 100%%\\nLine 3\\n"',
+        ],
+        RunOpts(log=Log.STDOUT, cwd=Path.cwd()),
+    )
+
+    assert result.returncode == 0
+    log_messages = [record.message for record in caplog.records]
+
+    # Should see Line 1, Progress: 100%, and Line 3
+    assert "Line 1" in log_messages
+    assert "Progress: 100%" in log_messages
+    assert "Line 3" in log_messages
+
+    # Should NOT see the intermediate progress messages
+    assert "Progress: 10%" not in log_messages
+    assert "Progress: 50%" not in log_messages