Merge pull request #2957 from jfinkels/head-preserve-no-final-newline

head: don't add trailing newline to end of file that didn't originally have one

src/uu/head/Cargo.toml

@@ -17,7 +17,7 @@ path = "src/head.rs"
 [dependencies]
 clap = { version = "3.0", features = ["wrap_help", "cargo"] }
 memchr = "2"
-uucore = { version=">=0.0.11", package="uucore", path="../../uucore", features=["ringbuffer"] }
+uucore = { version=">=0.0.11", package="uucore", path="../../uucore", features=["ringbuffer", "lines"] }
 
 [[bin]]
 name = "head"

src/uu/head/src/head.rs

@@ -11,6 +11,7 @@ use std::ffi::OsString;
 use std::io::{self, BufWriter, ErrorKind, Read, Seek, SeekFrom, Write};
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UError, UResult, USimpleError};
+use uucore::lines::lines;
 use uucore::show;
 
 const BUF_SIZE: usize = 65536;
@@ -35,10 +36,8 @@ mod options {
     pub const ZERO_NAME: &str = "ZERO";
     pub const FILES_NAME: &str = "FILE";
 }
-mod lines;
 mod parse;
 mod take;
-use lines::zlines;
 use take::take_all_but;
 use take::take_lines;
 
@@ -286,12 +285,14 @@ fn read_but_last_n_lines(
     if zero {
         let stdout = std::io::stdout();
         let mut stdout = stdout.lock();
-        for bytes in take_all_but(zlines(input), n) {
+        for bytes in take_all_but(lines(input, b'\0'), n) {
             stdout.write_all(&bytes?)?;
         }
     } else {
-        for line in take_all_but(input.lines(), n) {
+        let stdout = std::io::stdout();
-            println!("{}", line?);
+        let mut stdout = stdout.lock();
+        for bytes in take_all_but(lines(input, b'\n'), n) {
+            stdout.write_all(&bytes?)?;
         }
     }
     Ok(())

src/uu/head/src/lines.rs

@@ -1,75 +0,0 @@
-// spell-checker:ignore (vars) zline zlines
-
-//! Iterate over zero-terminated lines.
-use std::io::BufRead;
-
-/// The zero byte, representing the null character.
-const ZERO: u8 = 0;
-
-/// Returns an iterator over the lines of the given reader.
-///
-/// The iterator returned from this function will yield instances of
-/// [`std::io::Result`]<[`Vec`]<[`u8`]>>, representing the bytes of the line
-/// *including* the null character (with the possible exception of the
-/// last line, which may not have one).
-///
-/// # Examples
-///
-/// ```rust,ignore
-/// use std::io::Cursor;
-///
-/// let cursor = Cursor::new(b"x\0y\0z\0");
-/// let mut iter = zlines(cursor).map(|l| l.unwrap());
-/// assert_eq!(iter.next(), Some(b"x\0".to_vec()));
-/// assert_eq!(iter.next(), Some(b"y\0".to_vec()));
-/// assert_eq!(iter.next(), Some(b"z\0".to_vec()));
-/// assert_eq!(iter.next(), None);
-/// ```
-pub fn zlines<B>(buf: B) -> ZLines<B> {
-    ZLines { buf }
-}
-
-/// An iterator over the zero-terminated lines of an instance of `BufRead`.
-pub struct ZLines<B> {
-    buf: B,
-}
-
-impl<B: BufRead> Iterator for ZLines<B> {
-    type Item = std::io::Result<Vec<u8>>;
-
-    fn next(&mut self) -> Option<std::io::Result<Vec<u8>>> {
-        let mut buf = Vec::new();
-        match self.buf.read_until(ZERO, &mut buf) {
-            Ok(0) => None,
-            Ok(_) => Some(Ok(buf)),
-            Err(e) => Some(Err(e)),
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-
-    use crate::lines::zlines;
-    use std::io::Cursor;
-
-    #[test]
-    fn test_null_terminated() {
-        let cursor = Cursor::new(b"x\0y\0z\0");
-        let mut iter = zlines(cursor).map(|l| l.unwrap());
-        assert_eq!(iter.next(), Some(b"x\0".to_vec()));
-        assert_eq!(iter.next(), Some(b"y\0".to_vec()));
-        assert_eq!(iter.next(), Some(b"z\0".to_vec()));
-        assert_eq!(iter.next(), None);
-    }
-
-    #[test]
-    fn test_not_null_terminated() {
-        let cursor = Cursor::new(b"x\0y\0z");
-        let mut iter = zlines(cursor).map(|l| l.unwrap());
-        assert_eq!(iter.next(), Some(b"x\0".to_vec()));
-        assert_eq!(iter.next(), Some(b"y\0".to_vec()));
-        assert_eq!(iter.next(), Some(b"z".to_vec()));
-        assert_eq!(iter.next(), None);
-    }
-}

src/uu/tail/Cargo.toml

@@ -17,7 +17,7 @@ path = "src/tail.rs"
 [dependencies]
 clap = { version = "3.0", features = ["wrap_help", "cargo"] }
 libc = "0.2.42"
-uucore = { version=">=0.0.11", package="uucore", path="../../uucore", features=["ringbuffer"] }
+uucore = { version=">=0.0.11", package="uucore", path="../../uucore", features=["ringbuffer", "lines"] }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version="0.3", features=["fileapi", "handleapi", "processthreadsapi", "synchapi", "winbase"] }

src/uu/tail/src/tail.rs

@@ -16,11 +16,9 @@ extern crate clap;
 extern crate uucore;
 
 mod chunks;
-mod lines;
 mod parse;
 mod platform;
 use chunks::ReverseChunks;
-use lines::lines;
 
 use clap::{App, AppSettings, Arg};
 use std::collections::VecDeque;
@@ -33,6 +31,7 @@ use std::thread::sleep;
 use std::time::Duration;
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult, USimpleError};
+use uucore::lines::lines;
 use uucore::parse_size::{parse_size, ParseSizeError};
 use uucore::ringbuffer::RingBuffer;
 

src/uucore/Cargo.toml

@@ -55,6 +55,7 @@ encoding = ["data-encoding", "data-encoding-macro", "z85", "thiserror"]
 entries = ["libc"]
 fs = ["libc", "nix", "winapi-util"]
 fsext = ["libc", "time"]
+lines = []
 memo = ["itertools"]
 mode = ["libc"]
 perms = ["libc", "walkdir"]

src/uucore/src/lib/features.rs

@@ -6,6 +6,8 @@ pub mod encoding;
 pub mod fs;
 #[cfg(feature = "fsext")]
 pub mod fsext;
+#[cfg(feature = "lines")]
+pub mod lines;
 #[cfg(feature = "memo")]
 pub mod memo;
 #[cfg(feature = "ringbuffer")]

src/uucore/src/lib/features/lines.rs

@@ -2,15 +2,17 @@
 //  *
 //  * For the full copyright and license information, please view the LICENSE
 //  * file that was distributed with this source code.
+// spell-checker:ignore (vars)
 //! Iterate over lines, including the line ending character(s).
 //!
 //! This module provides the [`lines`] function, similar to the
 //! [`BufRead::lines`] method. While the [`BufRead::lines`] method
 //! yields [`String`] instances that do not include the line ending
-//! characters (`"\n"` or `"\r\n"`), our function yields [`String`]
+//! characters (`"\n"` or `"\r\n"`), our functions yield
-//! instances that include the line ending characters. This is useful
+//! [`Vec`]<['u8']> instances that include the line ending
-//! if the input data does not end with a newline character and you
+//! characters. This is useful if the input data does not end with a
-//! want to preserve the exact form of the input data.
+//! newline character and you want to preserve the exact form of the
+//! input data.
 use std::io::BufRead;
 
 /// Returns an iterator over the lines, including line ending characters.
@@ -51,7 +53,7 @@ use std::io::BufRead;
 /// assert_eq!(it.next(), Some(Vec::from("z")));
 /// assert_eq!(it.next(), None);
 /// ```
-pub(crate) fn lines<B>(reader: B, sep: u8) -> Lines<B>
+pub fn lines<B>(reader: B, sep: u8) -> Lines<B>
 where
     B: BufRead,
 {
@@ -62,7 +64,7 @@ where
 ///
 /// This struct is generally created by calling [`lines`] on a `BufRead`.
 /// Please see the documentation of [`lines`] for more details.
-pub(crate) struct Lines<B> {
+pub struct Lines<B> {
     buf: B,
     sep: u8,
 }

src/uucore/src/lib/lib.rs

@@ -38,6 +38,8 @@ pub use crate::features::encoding;
 pub use crate::features::fs;
 #[cfg(feature = "fsext")]
 pub use crate::features::fsext;
+#[cfg(feature = "lines")]
+pub use crate::features::lines;
 #[cfg(feature = "memo")]
 pub use crate::features::memo;
 #[cfg(feature = "ringbuffer")]

tests/by-util/test_head.rs

@@ -157,11 +157,17 @@ fn test_negative_byte_syntax() {
 #[test]
 fn test_negative_zero_lines() {
     new_ucmd!()
-        .args(&["--lines=-0"])
+        .arg("--lines=-0")
         .pipe_in("a\nb\n")
         .succeeds()
         .stdout_is("a\nb\n");
+    new_ucmd!()
+        .arg("--lines=-0")
+        .pipe_in("a\nb")
+        .succeeds()
+        .stdout_is("a\nb");
 }
+
 #[test]
 fn test_negative_zero_bytes() {
     new_ucmd!()