Match GNU semantics for missing EOF

While the rust coreutils semantics were arguably more correct,
they were different than the gnu split semantics when handling a
file without a trailing EOF. This patch addresses that difference
and allows passing one more GNU test suite.

src/uu/split/src/split.rs

@@ -37,8 +37,9 @@ static OPT_HEX_SUFFIXES: &str = "hex-suffixes";
 static OPT_SUFFIX_LENGTH: &str = "suffix-length";
 static OPT_DEFAULT_SUFFIX_LENGTH: &str = "0";
 static OPT_VERBOSE: &str = "verbose";
-//The ---io-blksize parameter is consumed and ignored.
+//The ---io and ---io-blksize parameters are consumed and ignored.
 //The parameter is included to make GNU coreutils tests pass.
+static OPT_IO: &str = "-io";
 static OPT_IO_BLKSIZE: &str = "-io-blksize";
 static OPT_ELIDE_EMPTY_FILES: &str = "elide-empty-files";
 
@@ -159,6 +160,13 @@ pub fn uu_app<'a>() -> Command<'a> {
                 .long(OPT_VERBOSE)
                 .help("print a diagnostic just before each output file is opened"),
         )
+        .arg(
+            Arg::new(OPT_IO)
+                .long(OPT_IO)
+                .alias(OPT_IO)
+                .takes_value(true)
+                .hide(true),
+        )
         .arg(
             Arg::new(OPT_IO_BLKSIZE)
                 .long(OPT_IO_BLKSIZE)
@@ -922,10 +930,22 @@ impl<'a> Write for LineBytesChunkWriter<'a> {
                 // then move on to the next chunk if necessary.
                 None => {
                     let end = self.num_bytes_remaining_in_current_chunk;
-                    let num_bytes_written = self.inner.write(&buf[..end.min(buf.len())])?;
-                    self.num_bytes_remaining_in_current_chunk -= num_bytes_written;
-                    total_bytes_written += num_bytes_written;
-                    buf = &buf[num_bytes_written..];
+
+                    // This is ugly but here to match GNU behavior. If the input
+                    // doesn't end with a \n, pretend that it does for handling
+                    // the second to last segment chunk. See `line-bytes.sh`.
+                    if end == buf.len()
+                        && self.num_bytes_remaining_in_current_chunk
+                            < self.chunk_size.try_into().unwrap()
+                        && buf[buf.len() - 1] != b'\n'
+                    {
+                        self.num_bytes_remaining_in_current_chunk = 0;
+                    } else {
+                        let num_bytes_written = self.inner.write(&buf[..end.min(buf.len())])?;
+                        self.num_bytes_remaining_in_current_chunk -= num_bytes_written;
+                        total_bytes_written += num_bytes_written;
+                        buf = &buf[num_bytes_written..];
+                    }
                 }
 
                 // If there is a newline character and the line

tests/by-util/test_split.rs

@@ -659,6 +659,22 @@ fn test_line_bytes_no_empty_file() {
     assert!(!at.plus("xak").exists());
 }
 
+#[test]
+fn test_line_bytes_no_eof() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    ucmd.args(&["-C", "3"])
+        .pipe_in("1\n2222\n3\n4")
+        .succeeds()
+        .no_stdout()
+        .no_stderr();
+    assert_eq!(at.read("xaa"), "1\n");
+    assert_eq!(at.read("xab"), "222");
+    assert_eq!(at.read("xac"), "2\n");
+    assert_eq!(at.read("xad"), "3\n");
+    assert_eq!(at.read("xae"), "4");
+    assert!(!at.plus("xaf").exists());
+}
+
 #[test]
 fn test_guard_input() {
     let ts = TestScenario::new(util_name!());

tests/fixtures/split/noeof.txt

@@ -0,0 +1,4 @@
+1
+2222
+3
+4