fix: check if stdout is a tty before writing to it (#7)

src/terminal/unix.rs

@@ -62,16 +62,15 @@ impl io::Write for FileDescriptor {
 }
 
 fn open_pty() -> io::Result<(FileDescriptor, FileDescriptor)> {
-    let (read, write) = if io::stdin().is_terminal() {
-        (FileDescriptor::STDIN, FileDescriptor::STDOUT)
+    let read = if io::stdin().is_terminal() {
+        FileDescriptor::STDIN
     } else {
-        let file = fs::OpenOptions::new()
-            .read(true)
-            .write(true)
-            .open("/dev/tty")?;
-        let read = FileDescriptor::Owned(file.into());
-        let write = read.try_clone()?;
-        (read, write)
+        open_dev_tty()?
+    };
+    let write = if io::stdout().is_terminal() {
+        FileDescriptor::STDOUT
+    } else {
+        open_dev_tty()?
     };
 
     // Activate non-blocking mode for the reader.
@@ -81,6 +80,14 @@ fn open_pty() -> io::Result<(FileDescriptor, FileDescriptor)> {
     Ok((read, write))
 }
 
+fn open_dev_tty() -> io::Result<FileDescriptor> {
+    let file = fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .open("/dev/tty")?;
+    Ok(FileDescriptor::Owned(file.into()))
+}
+
 impl From<termios::Winsize> for WindowSize {
     fn from(size: termios::Winsize) -> Self {
         Self {

src/terminal/windows.rs

@@ -293,24 +293,23 @@ impl io::Write for OutputHandle {
 }
 
 fn open_pty() -> io::Result<(InputHandle, OutputHandle)> {
-    let (input, output) = if io::stdin().is_terminal() {
-        (Handle::stdin(), Handle::stdout())
+    let input = if io::stdin().is_terminal() {
+        Handle::stdin()
     } else {
-        let input = fs::OpenOptions::new()
-            .read(true)
-            .write(true)
-            .open("CONIN$")?
-            .into();
-        let output = fs::OpenOptions::new()
-            .read(true)
-            .write(true)
-            .open("CONOUT$")?
-            .into();
-        (input, output)
+        open_file("CONIN$")?.into()
+    };
+    let output = if io::stdout().is_terminal() {
+        Handle::stdout()
+    } else {
+        open_file("CONOUT$")?.into()
     };
     Ok((InputHandle::new(input), OutputHandle::new(output)))
 }
 
+fn open_file(path: &str) -> io::Result<File> {
+    fs::OpenOptions::new().read(true).write(true).open(path)
+}
+
 // CREDIT: Again, like the UnixTerminal in the unix module this is mostly based on WezTerm but
 // only covers the parts not related to the event source.
 // <https://github.com/wezterm/wezterm/blob/a87358516004a652ad840bc1661bdf65ffc89b43/termwiz/src/terminal/windows.rs#L482-L860>