mirror of
https://github.com/wez/wezterm.git
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93 lines
3.2 KiB
Rust
93 lines
3.2 KiB
Rust
//! Runs a command with a fixed terminal size.
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//! This is used by wezterm's doc building automation to keep
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//! the --help output within a reasonable width
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use portable_pty::{CommandBuilder, NativePtySystem, PtySize, PtySystem};
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use std::sync::mpsc::channel;
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fn main() {
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let pty_system = NativePtySystem::default();
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let pair = pty_system
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.openpty(PtySize {
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rows: 24,
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cols: 80,
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pixel_width: 0,
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pixel_height: 0,
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})
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.unwrap();
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let mut args = std::env::args_os().skip(1);
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let mut cmd = CommandBuilder::new(args.next().unwrap());
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cmd.args(args);
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let mut child = pair.slave.spawn_command(cmd).unwrap();
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// Release any handles owned by the slave: we don't need it now
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// that we've spawned the child.
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drop(pair.slave);
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// Read the output in another thread.
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// This is important because it is easy to encounter a situation
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// where read/write buffers fill and block either your process
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// or the spawned process.
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let (tx, rx) = channel();
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let mut reader = pair.master.try_clone_reader().unwrap();
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std::thread::spawn(move || {
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// Consume the output from the child
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let mut s = String::new();
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reader.read_to_string(&mut s).unwrap();
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tx.send(s).unwrap();
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});
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{
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// Obtain the writer.
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// When the writer is dropped, EOF will be sent to
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// the program that was spawned.
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// It is important to take the writer even if you don't
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// send anything to its stdin so that EOF can be
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// generated, otherwise you risk deadlocking yourself.
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let mut writer = pair.master.take_writer().unwrap();
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if cfg!(target_os = "macos") {
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// macOS quirk: the child and reader must be started and
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// allowed a brief grace period to run before we allow
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// the writer to drop. Otherwise, the data we send to
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// the kernel to trigger EOF is interleaved with the
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// data read by the reader! WTF!?
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// This appears to be a race condition for very short
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// lived processes on macOS.
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// I'd love to find a more deterministic solution to
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// this than sleeping.
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std::thread::sleep(std::time::Duration::from_millis(20));
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}
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// This example doesn't need to write anything, but if you
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// want to send data to the child, you'd set `to_write` to
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// that data and do it like this:
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let to_write = "";
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if !to_write.is_empty() {
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// To avoid deadlock, wrt. reading and waiting, we send
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// data to the stdin of the child in a different thread.
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std::thread::spawn(move || {
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writer.write_all(to_write.as_bytes()).unwrap();
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});
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}
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}
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// Wait for the child to complete
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eprintln!("child status: {:?}", child.wait().unwrap());
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// Take care to drop the master after our processes are
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// done, as some platforms get unhappy if it is dropped
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// sooner than that.
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drop(pair.master);
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// Now wait for the output to be read by our reader thread
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let output = rx.recv().unwrap();
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let output = output.replace("\r\n", "\n");
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print!("{output}");
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}
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