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//! Shell-related `Transcript` methods.
use std::{
io::{self, BufRead, BufReader, LineWriter, Read},
iter,
process::{Command, Stdio},
sync::mpsc,
thread,
time::Duration,
};
use super::ShellOptions;
use crate::{
traits::{ShellProcess, SpawnShell, SpawnedShell},
Captured, Interaction, Transcript, UserInput,
};
#[derive(Debug)]
struct Timeouts {
inner: iter::Chain<iter::Once<Duration>, iter::Repeat<Duration>>,
}
impl Timeouts {
fn new<Cmd: SpawnShell>(options: &ShellOptions<Cmd>) -> Self {
Self {
inner: iter::once(options.init_timeout + options.io_timeout)
.chain(iter::repeat(options.io_timeout)),
}
}
fn next(&mut self) -> Duration {
self.inner.next().unwrap() // safe by construction; the iterator is indefinite
}
}
impl Transcript {
#[cfg(not(windows))]
fn write_line(writer: &mut impl io::Write, line: &str) -> io::Result<()> {
writeln!(writer, "{}", line)
}
// Lines need to end with `\r\n` to be properly processed, at least when writing to a PTY.
#[cfg(windows)]
fn write_line(writer: &mut impl io::Write, line: &str) -> io::Result<()> {
writeln!(writer, "{}\r", line)
}
fn read_echo(
input_line: &str,
lines_recv: &mpsc::Receiver<Vec<u8>>,
io_timeout: Duration,
) -> io::Result<()> {
if lines_recv.recv_timeout(io_timeout).is_ok() {
Ok(())
} else {
let err = format!(
"could not read all input `{}` back from an echoing terminal",
input_line
);
Err(io::Error::new(io::ErrorKind::BrokenPipe, err))
}
}
/// Constructs a transcript from the sequence of given user `input`s.
///
/// The inputs are executed in the shell specified in `options`. A single shell is shared
/// among all commands.
///
/// # Errors
///
/// - Returns an error if spawning the shell or any operations with it fail (such as reading
/// stdout / stderr, or writing commands to stdin), or if the shell exits before all commands
/// are executed.
#[allow(clippy::missing_panics_doc)] // false positive
pub fn from_inputs<Cmd: SpawnShell>(
options: &mut ShellOptions<Cmd>,
inputs: impl IntoIterator<Item = UserInput>,
) -> io::Result<Self> {
let SpawnedShell {
mut shell,
reader,
writer,
} = options.spawn_shell()?;
let stdout = BufReader::new(reader);
let (out_lines_send, out_lines_recv) = mpsc::channel();
let io_handle = thread::spawn(move || {
let mut lines = stdout.split(b'\n');
while let Some(Ok(line)) = lines.next() {
if out_lines_send.send(line).is_err() {
break; // the receiver was dropped, we don't care any more
}
}
});
let mut stdin = LineWriter::new(writer);
let mut timeouts = Timeouts::new(options);
// Push initialization commands.
if shell.is_echoing() {
for cmd in &options.init_commands {
Self::write_line(&mut stdin, cmd)?;
Self::read_echo(cmd, &out_lines_recv, timeouts.next())?;
// Drain all other output as well.
while out_lines_recv.recv_timeout(timeouts.next()).is_ok() {
// Intentionally empty.
}
}
} else {
// Since we don't care about getting all echoes back, we can push all lines at once and
// drain the output afterwards.
for cmd in &options.init_commands {
Self::write_line(&mut stdin, cmd)?;
}
}
// Drain all output left after commands and let the shell get fully initialized.
while out_lines_recv.recv_timeout(timeouts.next()).is_ok() {
// Intentionally empty.
}
// At this point, at least one item was requested from `timeout_iter`, so the further code
// may safely use `options.io_timeout`.
let mut transcript = Self::new();
for input in inputs {
// Check if the shell is still alive. It seems that older Rust versions allow
// to write to `stdin` even after the shell exits.
shell.check_is_alive()?;
let input_lines = input.text.split('\n');
for input_line in input_lines {
Self::write_line(&mut stdin, input_line)?;
if shell.is_echoing() {
Self::read_echo(input_line, &out_lines_recv, options.io_timeout)?;
}
}
let mut output = String::new();
while let Ok(mut line) = out_lines_recv.recv_timeout(options.io_timeout) {
if line.last() == Some(&b'\r') {
// Normalize `\r\n` line ending to `\n`.
line.pop();
}
let line = String::from_utf8(line)
.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err.utf8_error()))?;
if let Some(mapped_line) = (options.line_mapper)(line) {
output.push_str(&mapped_line);
output.push('\n');
}
}
if output.ends_with('\n') {
output.truncate(output.len() - 1);
}
transcript.interactions.push(Interaction {
input,
output: Captured::new(output),
});
}
drop(stdin); // signals to shell that we're done
// Give a chance for the shell process to exit. This will reduce kill errors later.
thread::sleep(options.io_timeout / 4);
shell.terminate()?;
io_handle.join().ok(); // the I/O thread should not panic, so we ignore errors here
Ok(transcript)
}
/// Captures stdout / stderr of the provided `command` and adds it to [`Self::interactions()`].
///
/// The `command` is spawned with closed stdin. This method blocks until the command exits.
/// The method succeeds regardless of the exit status of the `command`.
///
/// # Errors
///
/// - Returns an error if spawning the `command` or any operations with it fail (such as reading
/// stdout / stderr).
pub fn capture_output(
&mut self,
input: UserInput,
command: &mut Command,
) -> io::Result<&mut Self> {
let (mut pipe_reader, pipe_writer) = os_pipe::pipe()?;
let mut child = command
.stdin(Stdio::null())
.stdout(pipe_writer.try_clone()?)
.stderr(pipe_writer)
.spawn()?;
// Drop pipe writers. This is necessary for the pipe reader to receive EOF.
command.stdout(Stdio::null()).stderr(Stdio::null());
let mut output = vec![];
pipe_reader.read_to_end(&mut output)?;
child.wait()?;
let output = String::from_utf8(output)
.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err.utf8_error()))?;
self.interactions.push(Interaction {
input,
output: Captured::new(output),
});
Ok(self)
}
}