yes: use std::io::copy

Author: xtqqczze

src/uu/yes/src/yes.rs

@@ -7,7 +7,7 @@
 
 use clap::{Arg, ArgAction, Command, builder::ValueParser};
 use std::ffi::OsString;
-use std::io::{self, Write};
+use std::io::{self};
 use uucore::error::{UResult, USimpleError, strip_errno};
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use uucore::pipes::MAX_ROOTLESS_PIPE_SIZE;
@@ -100,54 +100,11 @@ fn repeat_content_to_capacity(buf: &mut Vec<u8>) {
     }
 }
 
-#[cfg(not(any(target_os = "linux", target_os = "android")))]
-pub fn exec(mut bytes: Vec<u8>) -> io::Result<()> {
-    repeat_content_to_capacity(&mut bytes);
-    let bytes = bytes.as_slice();
-    let mut stdout = io::stdout().lock();
-    loop {
-        stdout.write_all(bytes)?;
-    }
-}
-
-#[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn exec(mut bytes: Vec<u8>) -> io::Result<()> {
-    use uucore::pipes::{pipe, splice, tee};
-
-    const PAGE_SIZE: usize = 4096;
-    let aligned = PAGE_SIZE.is_multiple_of(bytes.len());
     repeat_content_to_capacity(&mut bytes);
-    let bytes = bytes.as_slice();
-    let mut stdout = io::stdout(); // no need to lock with zero-copy
-    // don't show any error from fast-path and fallback to write for proper message
-    if let Ok((p_read, mut p_write)) = pipe()
-            // todo: zero-copy with default size when fcntl failed
-            && rustix::pipe::fcntl_setpipe_size(&stdout, MAX_ROOTLESS_PIPE_SIZE).is_ok()
-            && p_write.write_all(bytes).is_ok()
-    {
-        if aligned && tee(&p_read, &stdout, MAX_ROOTLESS_PIPE_SIZE).is_ok() {
-            while let Ok(1..) = tee(&p_read, &stdout, MAX_ROOTLESS_PIPE_SIZE) {}
-        } else if let Ok((broker_read, broker_write)) = pipe() {
-            // tee() cannot control offset and write to non-pipe
-            'hybrid: while let Ok(mut remain) = tee(&p_read, &broker_write, MAX_ROOTLESS_PIPE_SIZE)
-            {
-                debug_assert!(remain == bytes.len(), "splice() should cleanup pipe");
-                while remain > 0 {
-                    if let Ok(s) = splice(&broker_read, &stdout, remain) {
-                        remain -= s;
-                    } else {
-                        // avoid output breakage with reduced remain even if it would not happen
-                        stdout.write_all(&bytes[bytes.len() - remain..])?;
-                        break 'hybrid;
-                    }
-                }
-            }
-        }
-    }
-    // fallback
-    let mut stdout = stdout.lock();
+    let mut stdout = uucore::stdio::stdout_raw();
     loop {
-        stdout.write_all(bytes)?;
+        io::copy(&mut bytes.as_slice(), &mut *stdout)?;
     }
 }