From a1846d05798763cfeba922ec3b9ec9b9d76aebf8 Mon Sep 17 00:00:00 2001
From: Andy Kipp <anki-code@users.noreply.github.com>
Date: Thu, 8 Aug 2024 14:26:33 +0200
Subject: [PATCH] Fix safe readlines: `AttributeError: 'NoneType' object has no
 attribute 'readlines'` (#5646)

* fix

* news

* fix

---------

Co-authored-by: a <1@1.1>
---
 news/fix_safe_readlines.rst | 23 +++++++++++++++++++++++
 xonsh/procs/pipelines.py    |  4 +++-
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 news/fix_safe_readlines.rst

diff --git a/news/fix_safe_readlines.rst b/news/fix_safe_readlines.rst
new file mode 100644
index 000000000..fe4988298
--- /dev/null
+++ b/news/fix_safe_readlines.rst
@@ -0,0 +1,23 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* Fixed exception "object has no attribute readlines" in case of redirect callable alias output.
+
+**Security:**
+
+* <news item>
diff --git a/xonsh/procs/pipelines.py b/xonsh/procs/pipelines.py
index eb136c64a..eec6c6c9e 100644
--- a/xonsh/procs/pipelines.py
+++ b/xonsh/procs/pipelines.py
@@ -62,6 +62,8 @@ def SIGNAL_MESSAGES():
 
 def safe_readlines(handle, hint=-1):
     """Attempts to read lines without throwing an error."""
+    if handle is None:
+        return []
     try:
         lines = handle.readlines(hint)
     except OSError:
@@ -276,7 +278,7 @@ class CommandPipeline:
                     lines = b.splitlines(keepends=True)
                     yield from lines
                     self.end(tee_output=False)
-                elif self.captured == "stdout":
+                elif self.captured == "stdout" and stdout is not None:
                     b = stdout.read()
                     s = self._decode_uninew(b, universal_newlines=True)
                     self.lines = s.splitlines(keepends=True)