From 5139ed4ba9e3c094aa91c041c75feb10fa9d6e3a Mon Sep 17 00:00:00 2001
From: oech3 <79379754+oech3@users.noreply.github.com>
Date: Sat, 1 Aug 2026 21:04:44 +0900
Subject: [PATCH] nl: remove unnecessary .is_dir()

---
 src/uu/nl/src/nl.rs | 57 +++++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 25 deletions(-)

diff --git a/src/uu/nl/src/nl.rs b/src/uu/nl/src/nl.rs
index 37ec112451a..9f52fa8d93a 100644
--- a/src/uu/nl/src/nl.rs
+++ b/src/uu/nl/src/nl.rs
@@ -243,26 +243,17 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     for file in &files {
         if file == "-" {
             let mut buffer = BufReader::new(stdin());
-            nl(&mut buffer, &mut stats, &settings)?;
+            nl(&mut buffer, &mut stats, &settings, Path::new("-"))?;
         } else {
             let path = Path::new(file);
-
-            if path.is_dir() {
-                show_error!(
-                    "{}",
-                    translate!("nl-error-is-directory", "path" => path.maybe_quote())
-                );
-                set_exit_code(1);
-            } else {
-                match File::open(path) {
-                    Ok(reader) => {
-                        let mut buffer = BufReader::new(reader);
-                        nl(&mut buffer, &mut stats, &settings)?;
-                    }
-                    Err(e) => {
-                        show_error!("{}", e.map_err_context(|| file.maybe_quote().to_string()));
-                        set_exit_code(1);
-                    }
+            match File::open(path) {
+                Ok(reader) => {
+                    let mut buffer = BufReader::new(reader);
+                    nl(&mut buffer, &mut stats, &settings, path)?;
+                }
+                Err(e) => {
+                    show_error!("{}", e.map_err_context(|| file.maybe_quote().to_string()));
+                    set_exit_code(1);
                 }
             }
         }
@@ -387,19 +378,35 @@ fn write_line(writer: &mut impl Write, line: &[u8]) -> io::Result<()> {
 }
 
 /// `nl` implements the main functionality for an individual buffer.
-fn nl<T: Read>(reader: &mut BufReader<T>, stats: &mut Stats, settings: &Settings) -> UResult<()> {
+fn nl<T: Read>(
+    reader: &mut BufReader<T>,
+    stats: &mut Stats,
+    settings: &Settings,
+    path: &Path,
+) -> UResult<()> {
     let mut writer = BufWriter::new(stdout());
     let mut current_numbering_style = &settings.body_numbering;
     let mut line = Vec::new();
 
     loop {
         line.clear();
-        // reads up to and including b'\n'; returns 0 on EOF
-        let n = reader
-            .read_until(b'\n', &mut line)
-            .map_err_context(|| translate!("nl-error-could-not-read-line"))?;
-        if n == 0 {
-            break;
+        // reads up to and including b'\n'
+        match reader.read_until(b'\n', &mut line) {
+            Ok(0) => break, // EOF
+            Ok(_) => {}
+            #[cfg(any(target_os = "wasi", target_os = "windows"))] // wrong error message
+            Err(_) if path.is_dir() => {
+                return Err(io::Error::new(
+                    io::ErrorKind::IsADirectory,
+                    translate!("nl-error-is-directory", "path" => path.maybe_quote()),
+                )
+                .into());
+            }
+            #[cfg(not(any(target_os = "wasi", target_os = "windows")))]
+            Err(e) if e.kind() == io::ErrorKind::IsADirectory => {
+                return Err(e).map_err_context(|| path.maybe_quote().to_string());
+            }
+            Err(e) => return Err(e).map_err_context(|| translate!("nl-error-could-not-read-line")),
         }
 
         let _ = line.pop_if(|byte| *byte == b'\n');