sort: report merge output flush errors

src/uu/sort/src/merge.rs

@@ -25,7 +25,9 @@ use std::{
 };
 
 use compare::Compare;
+use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult};
+use uucore::translate;
 
 use crate::{
     GlobalSettings, Output, SortError,
@@ -304,8 +306,14 @@ struct FileMerger<'a> {
 impl FileMerger<'_> {
     /// Write the merged contents to the output file.
     fn write_all(self, settings: &GlobalSettings, output: Output) -> UResult<()> {
+        let output_name = output
+            .as_output_name()
+            .unwrap_or(OsStr::new("standard output"))
+            .to_owned();
+        let ctx = || translate!("sort-error-write-failed", "output" => output_name.maybe_quote());
         let mut out = output.into_write();
-        self.write_all_to(settings, &mut out)
+        self.write_all_to(settings, &mut out)?;
+        out.flush().map_err_context(ctx)
     }
 
     fn write_all_to(mut self, settings: &GlobalSettings, out: &mut impl Write) -> UResult<()> {

tests/by-util/test_sort.rs

@@ -1182,6 +1182,22 @@ fn test_merge_write_error_does_not_panic() {
     }
 }
 
+#[test]
+#[cfg(target_os = "linux")]
+fn test_merge_flush_error_is_reported() {
+    use std::fs::File;
+
+    let ts = TestScenario::new("sort");
+    ts.fixtures.write("input.txt", "line\n");
+
+    let dev_full = File::create("/dev/full").expect("Failed to open /dev/full");
+    ts.ucmd()
+        .args(&["-m", "input.txt"])
+        .set_stdout(dev_full)
+        .fails()
+        .stderr_contains("No space left on device");
+}
+
 #[test]
 fn test_merge_unique() {
     new_ucmd!()