wc: remove splice_exact

Author: oech3

src/uu/wc/src/count_fast.rs

@@ -27,7 +27,7 @@ const FILE_ATTRIBUTE_NORMAL: u32 = 128;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use libc::S_IFIFO;
 #[cfg(any(target_os = "linux", target_os = "android"))]
-use uucore::pipes::{MAX_ROOTLESS_PIPE_SIZE, pipe, splice, splice_exact};
+use uucore::pipes::{MAX_ROOTLESS_PIPE_SIZE, pipe, splice};
 
 const BUF_SIZE: usize = 64 * 1024;
 
@@ -59,9 +59,12 @@ fn count_bytes_using_splice(fd: &impl AsFd) -> Result<usize, usize> {
         loop {
             match splice(fd, &pipe_wr, MAX_ROOTLESS_PIPE_SIZE) {
                 Ok(0) => return Ok(byte_count),
-                Ok(res) => {
-                    byte_count += res;
-                    splice_exact(&pipe_rd, &null_file, res).map_err(|_| byte_count)?;
+                Ok(mut discard) => {
+                    byte_count += discard;
+                    while discard > 0 {
+                        // pipe to null is not blocked. So this loop is just once at most cases...
+                        discard -= splice(&pipe_rd, &null_file, discard).map_err(|_| byte_count)?;
+                    }
                 }
                 Err(_) => return Err(byte_count),
             }