Implement exact reads for StdinRaw

Author: thaliaarchi

library/std/src/io/stdio.rs

@@ -120,6 +120,20 @@ impl Read for StdinRaw {
     fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
         handle_ebadf(self.0.read_to_string(buf), 0)
     }
+
+    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
+        if buf.is_empty() {
+            return Ok(());
+        }
+        handle_ebadf_err(self.0.read_exact(buf), io::Error::READ_EXACT_EOF)
+    }
+
+    fn read_buf_exact(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
+        if buf.capacity() == 0 {
+            return Ok(());
+        }
+        handle_ebadf_err(self.0.read_buf_exact(buf), io::Error::READ_EXACT_EOF)
+    }
 }
 
 impl Write for StdoutRaw {
@@ -200,6 +214,13 @@ fn handle_ebadf_lazy<T>(r: io::Result<T>, default: impl FnOnce() -> T) -> io::Re
     }
 }
 
+fn handle_ebadf_err<T>(r: io::Result<T>, default_err: io::Error) -> io::Result<T> {
+    match r {
+        Err(ref e) if stdio::is_ebadf(e) => Err(default_err),
+        r => r,
+    }
+}
+
 /// A handle to the standard input stream of a process.
 ///
 /// Each handle is a shared reference to a global buffer of input data to this