Merge pull request #3274 from no382001/issue3262

fix read/1 on non-TTY stdin blocking until newline

src/machine/streams.rs

@@ -23,7 +23,7 @@ use std::fmt::Debug;
 use std::fs::{File, OpenOptions};
 use std::hash::Hash;
 use std::io;
-use std::io::{Cursor, ErrorKind, Read, Seek, SeekFrom, Write};
+use std::io::{Cursor, ErrorKind, IsTerminal, Read, Seek, SeekFrom, Write};
 use std::mem::ManuallyDrop;
 use std::net::{Shutdown, TcpStream};
 use std::ops::{Deref, DerefMut};
@@ -657,6 +657,16 @@ impl Stream {
 
     #[inline]
     pub fn stdin(arena: &mut Arena, add_history: bool) -> Stream {
+        #[cfg(unix)]
+        if !std::io::stdin().is_terminal() {
+            use std::os::unix::io::{FromRawFd, RawFd};
+            // dup fd 0 so the File can be owned (and closed later) without
+            // closing the real stdin.
+            let fd = unsafe { libc::dup(0 as RawFd) };
+            let file = unsafe { File::from_raw_fd(fd) };
+            return Stream::from_file_as_input(atom!("user_input"), file, arena);
+        }
+
         Stream::Readline(arena_alloc!(
             StreamLayout::new(ReadlineStream::new("", add_history)),
             arena