tr: generate an error if the input is a directory

src/uu/tr/src/operation.rs

@@ -23,7 +23,7 @@ use std::{
     io::{BufRead, Write},
     ops::Not,
 };
-use uucore::error::UError;
+use uucore::error::{UError, UResult, USimpleError};
 use uucore::show_warning;
 
 #[derive(Debug, Clone)]
@@ -608,23 +608,33 @@ impl SymbolTranslator for SqueezeOperation {
     }
 }
 
-pub fn translate_input<T, R, W>(input: &mut R, output: &mut W, mut translator: T)
+pub fn translate_input<T, R, W>(input: &mut R, output: &mut W, mut translator: T) -> UResult<()>
 where
     T: SymbolTranslator,
     R: BufRead,
     W: Write,
 {
     let mut buf = Vec::new();
     let mut output_buf = Vec::new();
+
     while let Ok(length) = input.read_until(b'\n', &mut buf) {
         if length == 0 {
-            break;
-        } else {
-            let filtered = buf.iter().filter_map(|c| translator.translate(*c));
-            output_buf.extend(filtered);
-            output.write_all(&output_buf).unwrap();
+            break; // EOF reached
         }
+
+        let filtered = buf.iter().filter_map(|&c| translator.translate(c));
+        output_buf.extend(filtered);
+
+        if let Err(e) = output.write_all(&output_buf) {
+            return Err(USimpleError::new(
+                1,
+                format!("{}: write error: {}", uucore::util_name(), e),
+            ));
+        }
+
         buf.clear();
         output_buf.clear();
     }
+
+    Ok(())
 }

src/uu/tr/src/tr.rs

@@ -132,24 +132,24 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
             let delete_op = DeleteOperation::new(set1);
             let squeeze_op = SqueezeOperation::new(set2);
             let op = delete_op.chain(squeeze_op);
-            translate_input(&mut locked_stdin, &mut buffered_stdout, op);
+            translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
         } else {
             let op = DeleteOperation::new(set1);
-            translate_input(&mut locked_stdin, &mut buffered_stdout, op);
+            translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
         }
     } else if squeeze_flag {
         if sets_len < 2 {
             let op = SqueezeOperation::new(set1);
-            translate_input(&mut locked_stdin, &mut buffered_stdout, op);
+            translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
         } else {
             let translate_op = TranslateOperation::new(set1, set2.clone())?;
             let squeeze_op = SqueezeOperation::new(set2);
             let op = translate_op.chain(squeeze_op);
-            translate_input(&mut locked_stdin, &mut buffered_stdout, op);
+            translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
         }
     } else {
         let op = TranslateOperation::new(set1, set2)?;
-        translate_input(&mut locked_stdin, &mut buffered_stdout, op);
+        translate_input(&mut locked_stdin, &mut buffered_stdout, op)?;
     }
     Ok(())
 }

tests/by-util/test_tr.rs

@@ -13,6 +13,15 @@ fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails().code_is(1);
 }
 
+#[test]
+fn test_invalid_input() {
+    new_ucmd!()
+        .args(&["1", "1", "<", "."])
+        .fails()
+        .code_is(1)
+        .stderr_contains("tr: extra operand '<'");
+}
+
 #[test]
 fn test_to_upper() {
     new_ucmd!()