tr: handle broken pipe gracefully

src/uu/tr/src/operation.rs

@@ -708,9 +708,16 @@
         let filtered = buf.iter().filter_map(|&c| translator.translate(c));
         output_buf.extend(filtered);
 
-        output
-            .write_all(&output_buf)
-            .map_err_context(|| get_message("tr-error-write-error"))?;
+        if let Err(err) = output.write_all(&output_buf) {
+            // Treat broken pipe as a successful termination, which is the
+            // expected behavior when stdout is a pipeline and the downstream
+            // process terminates.
+            if err.kind() == std::io::ErrorKind::BrokenPipe {
+                break;
+            } else {
+                return Err(err.map_err_context(|| get_message("tr-error-write-error")));
+            }
+        }
 
         buf.clear();
         output_buf.clear();

src/uu/tr/src/tr.rs

@@ -13,7 +13,7 @@ use operation::{
 };
 use std::collections::HashMap;
 use std::ffi::OsString;
-use std::io::{BufWriter, Write, stdin, stdout};
+use std::io::{BufWriter, ErrorKind, Write, stdin, stdout};
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult, USimpleError, UUsageError};
 use uucore::fs::is_stdin_directory;
@@ -157,9 +157,12 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
     }
 
-    buffered_stdout
-        .flush()
-        .map_err_context(|| get_message("tr-error-write-error"))?;
+    // Handle broken pipe errors gracefully during flush.
+    match buffered_stdout.flush() {
+        Ok(()) => {}
+        Err(err) if err.kind() == ErrorKind::BrokenPipe => {}
+        Err(err) => return Err(err.map_err_context(|| get_message("tr-error-write-error"))),
+    }
 
     Ok(())
 }

tests/by-util/test_tr.rs

@@ -1554,3 +1554,13 @@ fn test_failed_write_is_reported() {
         .fails()
         .stderr_is("tr: write error: No space left on device\n");
 }
+
+#[test]
+fn test_broken_pipe_no_error() {
+    new_ucmd!()
+        .args(&["e", "a"])
+        .pipe_in("hello".repeat(100))
+        .run_stdout_starts_with(b"")
+        .success()
+        .stderr_is("");
+}