yes: support non-UTF-8 args

Also, tighten the creation of the output buffer.  Rather than copy "y\n"
8192 times, or any other input some number of times, it can be doubled
in place using Vec::extend_from_within.

Cargo.lock

@@ -3379,6 +3379,7 @@ name = "uu_yes"
 version = "0.0.18"
 dependencies = [
  "clap",
+ "itertools",
  "nix",
  "uucore",
 ]

src/uu/yes/Cargo.toml

@@ -16,6 +16,7 @@ path = "src/yes.rs"
 
 [dependencies]
 clap = { workspace=true }
+itertools = { workspace=true }
 
 [target.'cfg(unix)'.dependencies]
 uucore = { workspace=true, features=["pipes", "signals"] }

src/uu/yes/src/yes.rs

@@ -7,8 +7,11 @@
 
 /* last synced with: yes (GNU coreutils) 8.13 */
 
-use clap::{Arg, ArgAction, Command};
-use std::borrow::Cow;
+// cSpell:ignore strs
+
+use clap::{builder::ValueParser, Arg, ArgAction, Command};
+use std::error::Error;
+use std::ffi::OsString;
 use std::io::{self, Write};
 use uucore::error::{UResult, USimpleError};
 #[cfg(unix)]
@@ -28,19 +31,11 @@ const BUF_SIZE: usize = 16 * 1024;
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let matches = uu_app().try_get_matches_from(args)?;
 
-    let string = if let Some(values) = matches.get_many::<String>("STRING") {
-        let mut result = values.fold(String::new(), |res, s| res + s + " ");
-        result.pop();
-        result.push('\n');
-        Cow::from(result)
-    } else {
-        Cow::from("y\n")
-    };
+    let mut buffer = Vec::with_capacity(BUF_SIZE);
+    args_into_buffer(&mut buffer, matches.get_many::<OsString>("STRING")).unwrap();
+    prepare_buffer(&mut buffer);
 
-    let mut buffer = [0; BUF_SIZE];
-    let bytes = prepare_buffer(&string, &mut buffer);
-
-    match exec(bytes) {
+    match exec(&buffer) {
         Ok(()) => Ok(()),
         Err(err) if err.kind() == io::ErrorKind::BrokenPipe => Ok(()),
         Err(err) => Err(USimpleError::new(1, format!("standard output: {err}"))),
@@ -51,21 +46,73 @@ pub fn uu_app() -> Command {
     Command::new(uucore::util_name())
         .about(ABOUT)
         .override_usage(format_usage(USAGE))
-        .arg(Arg::new("STRING").action(ArgAction::Append))
+        .arg(
+            Arg::new("STRING")
+                .value_parser(ValueParser::os_string())
+                .action(ArgAction::Append),
+        )
         .infer_long_args(true)
 }
 
-fn prepare_buffer<'a>(input: &'a str, buffer: &'a mut [u8; BUF_SIZE]) -> &'a [u8] {
-    if input.len() < BUF_SIZE / 2 {
-        let mut size = 0;
-        while size < BUF_SIZE - input.len() {
-            let (_, right) = buffer.split_at_mut(size);
-            right[..input.len()].copy_from_slice(input.as_bytes());
-            size += input.len();
-        }
-        &buffer[..size]
+// Copies words from `i` into `buf`, separated by spaces.
+fn args_into_buffer<'a>(
+    buf: &mut Vec<u8>,
+    i: Option<impl Iterator<Item = &'a OsString>>,
+) -> Result<(), Box<dyn Error>> {
+    // TODO: this should be replaced with let/else once available in the MSRV.
+    let i = if let Some(i) = i {
+        i
     } else {
-        input.as_bytes()
+        buf.extend_from_slice(b"y\n");
+        return Ok(());
+    };
+
+    // On Unix (and wasi), OsStrs are just &[u8]'s underneath...
+    #[cfg(any(unix, target_os = "wasi"))]
+    {
+        #[cfg(unix)]
+        use std::os::unix::ffi::OsStrExt;
+        #[cfg(target_os = "wasi")]
+        use std::os::wasi::ffi::OsStrExt;
+
+        for part in itertools::intersperse(i.map(|a| a.as_bytes()), b" ") {
+            buf.extend_from_slice(part);
+        }
+    }
+
+    // But, on Windows, we must hop through a String.
+    #[cfg(not(any(unix, target_os = "wasi")))]
+    {
+        for part in itertools::intersperse(i.map(|a| a.to_str()), Some(" ")) {
+            let bytes = match part {
+                Some(part) => part.as_bytes(),
+                None => return Err("arguments contain invalid UTF-8".into()),
+            };
+            buf.extend_from_slice(bytes);
+        }
+    }
+
+    buf.push(b'\n');
+
+    Ok(())
+}
+
+// Assumes buf holds a single output line forged from the command line arguments, copies it
+// repeatedly until the buffer holds as many copies as it can under BUF_SIZE.
+fn prepare_buffer(buf: &mut Vec<u8>) {
+    if buf.len() * 2 > BUF_SIZE {
+        return;
+    }
+
+    assert!(!buf.is_empty());
+
+    let line_len = buf.len();
+    let target_size = line_len * (BUF_SIZE / line_len);
+
+    while buf.len() < target_size {
+        let to_copy = std::cmp::min(target_size - buf.len(), buf.len());
+        debug_assert_eq!(to_copy % line_len, 0);
+        buf.extend_from_within(..to_copy);
     }
 }
 
@@ -88,3 +135,67 @@ pub fn exec(bytes: &[u8]) -> io::Result<()> {
         stdout.write_all(bytes)?;
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_prepare_buffer() {
+        let tests = [
+            (150, 16350),
+            (1000, 16000),
+            (4093, 16372),
+            (4099, 12297),
+            (4111, 12333),
+            (2, 16384),
+            (3, 16383),
+            (4, 16384),
+            (5, 16380),
+            (8192, 16384),
+            (8191, 16382),
+            (8193, 8193),
+            (10000, 10000),
+            (15000, 15000),
+            (25000, 25000),
+        ];
+
+        for (line, final_len) in tests {
+            let mut v = std::iter::repeat(b'a').take(line).collect::<Vec<_>>();
+            prepare_buffer(&mut v);
+            assert_eq!(v.len(), final_len);
+        }
+    }
+
+    #[test]
+    fn test_args_into_buf() {
+        {
+            let mut v = Vec::with_capacity(BUF_SIZE);
+            args_into_buffer(&mut v, None::<std::slice::Iter<OsString>>).unwrap();
+            assert_eq!(String::from_utf8(v).unwrap(), "y\n");
+        }
+
+        {
+            let mut v = Vec::with_capacity(BUF_SIZE);
+            args_into_buffer(&mut v, Some([OsString::from("foo")].iter())).unwrap();
+            assert_eq!(String::from_utf8(v).unwrap(), "foo\n");
+        }
+
+        {
+            let mut v = Vec::with_capacity(BUF_SIZE);
+            args_into_buffer(
+                &mut v,
+                Some(
+                    [
+                        OsString::from("foo"),
+                        OsString::from("bar    baz"),
+                        OsString::from("qux"),
+                    ]
+                    .iter(),
+                ),
+            )
+            .unwrap();
+            assert_eq!(String::from_utf8(v).unwrap(), "foo bar    baz qux\n");
+        }
+    }
+}

tests/by-util/test_yes.rs

@@ -1,3 +1,4 @@
+use std::ffi::OsStr;
 use std::process::{ExitStatus, Stdio};
 
 #[cfg(unix)]
@@ -15,8 +16,10 @@ fn check_termination(result: ExitStatus) {
     assert!(result.success(), "yes did not exit successfully");
 }
 
+const NO_ARGS: &[&str] = &[];
+
 /// Run `yes`, capture some of the output, close the pipe, and verify it.
-fn run(args: &[&str], expected: &[u8]) {
+fn run(args: &[impl AsRef<OsStr>], expected: &[u8]) {
     let mut cmd = new_ucmd!();
     let mut child = cmd.args(args).set_stdout(Stdio::piped()).run_no_wait();
     let buf = child.stdout_exact_bytes(expected.len());
@@ -34,7 +37,7 @@ fn test_invalid_arg() {
 
 #[test]
 fn test_simple() {
-    run(&[], b"y\ny\ny\ny\n");
+    run(NO_ARGS, b"y\ny\ny\ny\n");
 }
 
 #[test]
@@ -44,7 +47,7 @@ fn test_args() {
 
 #[test]
 fn test_long_output() {
-    run(&[], "y\n".repeat(512 * 1024).as_bytes());
+    run(NO_ARGS, "y\n".repeat(512 * 1024).as_bytes());
 }
 
 /// Test with an output that seems likely to get mangled in case of incomplete writes.
@@ -88,3 +91,20 @@ fn test_piped_to_dev_full() {
         }
     }
 }
+
+#[test]
+#[cfg(any(unix, target_os = "wasi"))]
+fn test_non_utf8() {
+    #[cfg(unix)]
+    use std::os::unix::ffi::OsStrExt;
+    #[cfg(target_os = "wasi")]
+    use std::os::wasi::ffi::OsStrExt;
+
+    run(
+        &[
+            OsStr::from_bytes(b"\xbf\xff\xee"),
+            OsStr::from_bytes(b"bar"),
+        ],
+        &b"\xbf\xff\xee bar\n".repeat(5000),
+    );
+}