From 9415cf01c639788e414f63f7ae5e0231844df6d8 Mon Sep 17 00:00:00 2001
From: =?utf8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>
Date: Wed, 22 Oct 2025 16:31:15 +0100
Subject: [PATCH] nl: promptly diagnose write errors

* NEWS: Mention the improvement.
* src/nl.c (process_file): Exit if error outputting line.
* tests/misc/write-errors.sh: Enable the test case.
---
 NEWS                       | 2 +-
 src/nl.c                   | 3 +++
 tests/misc/write-errors.sh | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 55fe59503e..fb3359fd4d 100644
--- a/NEWS
+++ b/NEWS
@@ -43,7 +43,7 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Improvements
 
-  'fmt' will now exit promptly upon receiving a write error,
+  'fmt' and 'nl' will now exit promptly upon receiving a write error,
   which is significant when reading large / unbounded inputs.
 
   'install' now uses posix_spawn() to invoke the strip program more efficiently.
diff --git a/src/nl.c b/src/nl.c
index f243a29536..7060751621 100644
--- a/src/nl.c
+++ b/src/nl.c
@@ -425,6 +425,9 @@ process_file (FILE *fp)
           proc_text ();
           break;
         }
+
+      if (ferror (stdout))
+        write_error ();
     }
 }
 
diff --git a/tests/misc/write-errors.sh b/tests/misc/write-errors.sh
index 48f9c0f1a8..77f7fc860b 100755
--- a/tests/misc/write-errors.sh
+++ b/tests/misc/write-errors.sh
@@ -41,7 +41,7 @@ fold -c /dev/zero
 fold --version; yes | tr -d '\\n' | fold
 head -z -n-1 /dev/zero
 join -a 1 -z /dev/zero /dev/null
-# TODO: nl --version; yes | nl
+nl --version; yes | nl
 numfmt --version; yes 1 | numfmt
 od -v /dev/zero
 paste /dev/zero
-- 
2.47.3