csplit: detect and report write errors (#9855)

* csplit: detect and report write errors

* Add Rust integration tests for csplit write error detection

* csplit: fix doc comment for finish_split

src/uu/csplit/src/csplit.rs

@@ -127,7 +127,7 @@ where
     let ret = do_csplit(&mut split_writer, patterns_vec, &mut input_iter);
 
     // consume the rest, unless there was an error
-    if ret.is_ok() {
+    let ret = if ret.is_ok() {
         input_iter.rewind_buffer();
         if let Some((_, line)) = input_iter.next() {
             // There is remaining input: create a final split and copy remainder
@@ -136,14 +136,18 @@ where
             for (_, line) in input_iter {
                 split_writer.writeln(&line?)?;
             }
-            split_writer.finish_split();
+            split_writer.finish_split()
         } else if all_up_to_line && options.suppress_matched {
             // GNU semantics for integer patterns with --suppress-matched:
             // even if no remaining input, create a final (possibly empty) split
             split_writer.new_writer()?;
-            split_writer.finish_split();
+            split_writer.finish_split()
+        } else {
+            Ok(())
         }
-    }
+    } else {
+        ret
+    };
     // delete files on error by default
     if ret.is_err() && !options.keep_files {
         split_writer.delete_all_splits()?;
@@ -305,15 +309,24 @@ impl SplitWriter<'_> {
     ///
     /// # Errors
     ///
-    /// Some [`io::Error`] if the split could not be removed in case it should be elided.
-    fn finish_split(&mut self) {
+    /// Returns an error if flushing the writer fails.
+    fn finish_split(&mut self) -> Result<(), CsplitError> {
         if !self.dev_null {
+            // Flush the writer to ensure all data is written and errors are detected
+            if let Some(ref mut writer) = self.current_writer {
+                let file_name = self.options.split_name.get(self.counter - 1);
+                writer
+                    .flush()
+                    .map_err_context(|| file_name.clone())
+                    .map_err(CsplitError::from)?;
+            }
             if self.options.elide_empty_files && self.size == 0 {
                 self.counter -= 1;
             } else if !self.options.quiet {
                 println!("{}", self.size);
             }
         }
+        Ok(())
     }
 
     /// Removes all the split files that were created.
@@ -379,7 +392,7 @@ impl SplitWriter<'_> {
             }
             self.writeln(&line)?;
         }
-        self.finish_split();
+        self.finish_split()?;
         ret
     }
 
@@ -446,7 +459,7 @@ impl SplitWriter<'_> {
                                 self.writeln(&line?)?;
                             }
                             None => {
-                                self.finish_split();
+                                self.finish_split()?;
                                 return Err(CsplitError::LineOutOfRange(
                                     pattern_as_str.to_string(),
                                 ));
@@ -454,7 +467,7 @@ impl SplitWriter<'_> {
                         }
                         offset -= 1;
                     }
-                    self.finish_split();
+                    self.finish_split()?;
 
                     // if we have to suppress one line after we take the next and do nothing
                     if next_line_suppress_matched {
@@ -495,7 +508,7 @@ impl SplitWriter<'_> {
                         );
                     }
 
-                    self.finish_split();
+                    self.finish_split()?;
                     if input_iter.buffer_len() < offset_usize {
                         return Err(CsplitError::LineOutOfRange(pattern_as_str.to_string()));
                     }
@@ -511,7 +524,7 @@ impl SplitWriter<'_> {
             }
         }
 
-        self.finish_split();
+        self.finish_split()?;
         Err(CsplitError::MatchNotFound(pattern_as_str.to_string()))
     }
 }

tests/by-util/test_csplit.rs

@@ -1551,3 +1551,35 @@ fn test_csplit_non_utf8_paths() {
 
     ucmd.arg(&filename).arg("3").succeeds();
 }
+
+/// Test write error detection using /dev/full
+#[test]
+#[cfg(target_os = "linux")]
+fn test_write_error_dev_full() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.symlink_file("/dev/full", "xx01");
+
+    ucmd.args(&["-", "2"])
+        .pipe_in("1\n2\n")
+        .fails_with_code(1)
+        .stderr_contains("xx01: No space left on device");
+
+    // Files cleaned up by default
+    assert!(!at.file_exists("xx00"));
+}
+
+/// Test write error with -k keeps files
+#[test]
+#[cfg(target_os = "linux")]
+fn test_write_error_dev_full_keep_files() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.symlink_file("/dev/full", "xx01");
+
+    ucmd.args(&["-k", "-", "2"])
+        .pipe_in("1\n2\n")
+        .fails_with_code(1)
+        .stderr_contains("xx01: No space left on device");
+
+    assert!(at.file_exists("xx00"));
+    assert_eq!(at.read("xx00"), "1\n");
+}