tr: Flush BufWriter, fix double error context

Write errors led with `tr: tr: write error:`.

src/uu/tr/src/operation.rs

@@ -23,7 +23,7 @@ use std::{
     io::{BufRead, Write},
     ops::Not,
 };
-use uucore::error::{UError, UResult, USimpleError};
+use uucore::error::{FromIo, UError, UResult};
 use uucore::show_warning;
 
 #[derive(Debug, Clone)]
@@ -669,12 +669,9 @@ where
         let filtered = buf.iter().filter_map(|&c| translator.translate(c));
         output_buf.extend(filtered);
 
-        if let Err(e) = output.write_all(&output_buf) {
+        output
-            return Err(USimpleError::new(
+            .write_all(&output_buf)
-                1,
+            .map_err_context(|| "write error".into())?;
-                format!("{}: write error: {}", uucore::util_name(), e),
-            ));
-        }
 
         buf.clear();
         output_buf.clear();

src/uu/tr/src/tr.rs

@@ -14,9 +14,9 @@ use operation::{
     Sequence, SqueezeOperation, SymbolTranslator, TranslateOperation, translate_input,
 };
 use std::ffi::OsString;
-use std::io::{BufWriter, stdin, stdout};
+use std::io::{BufWriter, Write, stdin, stdout};
 use uucore::display::Quotable;
-use uucore::error::{UResult, USimpleError, UUsageError};
+use uucore::error::{FromIo, UResult, USimpleError, UUsageError};
 use uucore::fs::is_stdin_directory;
 use uucore::{format_usage, help_about, help_section, help_usage, os_str_as_bytes, show};
 
@@ -110,9 +110,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
     let stdin = stdin();
     let mut locked_stdin = stdin.lock();
-    let stdout = stdout();
+    let mut buffered_stdout = BufWriter::new(stdout().lock());
-    let locked_stdout = stdout.lock();
-    let mut buffered_stdout = BufWriter::new(locked_stdout);
 
     // According to the man page: translating only happens if deleting or if a second set is given
     let translating = !delete_flag && sets.len() > 1;
@@ -155,6 +153,11 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         let op = TranslateOperation::new(set1, set2)?;
         translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
     }
+
+    buffered_stdout
+        .flush()
+        .map_err_context(|| "write error".into())?;
+
     Ok(())
 }
 

tests/by-util/test_tr.rs

@@ -1545,3 +1545,14 @@ fn test_non_digit_repeat() {
         .fails()
         .stderr_only("tr: invalid repeat count 'c' in [c*n] construct\n");
 }
+
+#[cfg(target_os = "linux")]
+#[test]
+fn test_failed_write_is_reported() {
+    new_ucmd!()
+        .pipe_in("hello")
+        .args(&["e", "a"])
+        .set_stdout(std::fs::File::create("/dev/full").unwrap())
+        .fails()
+        .stderr_is("tr: write error: No space left on device\n");
+}