From 81a1fde9f43c83722f16da6798103fbaa7d842fa Mon Sep 17 00:00:00 2001
From: Smicry <smicry@vip.qq.com>
Date: Sun, 21 Nov 2021 12:37:56 +0800
Subject: [PATCH] tail use UResult

---
 src/uu/tail/src/tail.rs | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index d83f02724..655abcecf 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -191,7 +191,7 @@ fn uu_tail(settings: &Settings) -> UResult<()> {
 
         if use_stdin {
             let mut reader = BufReader::new(stdin());
-            unbounded_tail(&mut reader, settings);
+            unbounded_tail(&mut reader, settings)?;
 
             // Don't follow stdin since there are no checks for pipes/FIFOs
             //
@@ -230,7 +230,7 @@ fn uu_tail(settings: &Settings) -> UResult<()> {
                 }
             } else {
                 let mut reader = BufReader::new(file);
-                unbounded_tail(&mut reader, settings);
+                unbounded_tail(&mut reader, settings)?;
                 if settings.follow {
                     readers.push((Box::new(reader), filename));
                 }
@@ -239,7 +239,7 @@ fn uu_tail(settings: &Settings) -> UResult<()> {
     }
 
     if settings.follow {
-        follow(&mut readers[..], settings);
+        follow(&mut readers[..], settings)?;
     }
 
     Ok(())
@@ -342,10 +342,9 @@ pub fn uu_app() -> App<'static, 'static> {
         )
 }
 
-fn follow<T: BufRead>(readers: &mut [(T, &String)], settings: &Settings) {
-    assert!(settings.follow);
-    if readers.is_empty() {
-        return;
+fn follow<T: BufRead>(readers: &mut [(T, &String)], settings: &Settings) -> UResult<()> {
+    if readers.is_empty() || !settings.follow {
+        return Ok(());
     }
 
     let mut last = readers.len() - 1;
@@ -372,7 +371,7 @@ fn follow<T: BufRead>(readers: &mut [(T, &String)], settings: &Settings) {
                         }
                         print!("{}", datum);
                     }
-                    Err(err) => panic!("{}", err),
+                    Err(err) => return Err(USimpleError::new(1, err.to_string())),
                 }
             }
         }
@@ -381,6 +380,7 @@ fn follow<T: BufRead>(readers: &mut [(T, &String)], settings: &Settings) {
             break;
         }
     }
+    Ok(())
 }
 
 /// Iterate over bytes in the file, in reverse, until we find the
@@ -475,7 +475,7 @@ where
     }
 }
 
-fn unbounded_tail<T: Read>(reader: &mut BufReader<T>, settings: &Settings) {
+fn unbounded_tail<T: Read>(reader: &mut BufReader<T>, settings: &Settings) -> UResult<()> {
     // Read through each line/char and store them in a ringbuffer that always
     // contains count lines/chars. When reaching the end of file, output the
     // data in the ringbuf.
@@ -487,11 +487,13 @@ fn unbounded_tail<T: Read>(reader: &mut BufReader<T>, settings: &Settings) {
         }
         FilterMode::Bytes(count) => {
             for byte in unbounded_tail_collect(reader.bytes(), count, settings.beginning) {
-                let mut stdout = stdout();
-                print_byte(&mut stdout, byte);
+                if let Err(err) = stdout().write(&[byte]) {
+                    return Err(USimpleError::new(1, err.to_string()));
+                }
             }
         }
     }
+    Ok(())
 }
 
 fn is_seekable<T: Seek>(file: &mut T) -> bool {
@@ -500,13 +502,6 @@ fn is_seekable<T: Seek>(file: &mut T) -> bool {
         && file.seek(SeekFrom::Start(0)).is_ok()
 }
 
-#[inline]
-fn print_byte<T: Write>(stdout: &mut T, ch: u8) {
-    if let Err(err) = stdout.write(&[ch]) {
-        crash!(1, "{}", err);
-    }
-}
-
 fn parse_num(src: &str) -> Result<(usize, bool), ParseSizeError> {
     let mut size_string = src.trim();
     let mut starting_with = false;