Add IPC config subcommand

This patch adds a new mechanism for changing configuration options
without editing the configuration file, by sending options to running
instances through `alacritty msg`.

Each window will load Alacritty's configuration file by default and then
accept IPC messages for config updates using the `alacritty msg config`
subcommand. By default all windows will be updated, individual windows
can be addressed using `alacritty msg config --window-id
"$ALACRITTY_WINDOW_ID"`.

Each option will replace the config's current value and cannot be reset
until Alacritty is restarted or the option is overwritten with a new
value.

Configuration options are passed in the format `field.subfield=value`,
where `value` is interpreted as yaml.

Closes #472.

2 files changed, 6 insertions, 5 deletions

diff --git a/alacritty_terminal/src/tty/unix.rs b/alacritty_terminal/src/tty/unix.rs
index f52f0920..63da4f9c 100644
--- a/alacritty_terminal/src/tty/unix.rs
+++ b/alacritty_terminal/src/tty/unix.rs
@@ -148,7 +148,7 @@ fn default_shell_command(pw: &Passwd<'_>) -> Command {
 }
 
 /// Create a new TTY and return a handle to interact with it.
-pub fn new(config: &PtyConfig, window_size: WindowSize, window_id: Option<usize>) -> Result<Pty> {
+pub fn new(config: &PtyConfig, window_size: WindowSize, window_id: u64) -> Result<Pty> {
     let (master, slave) = make_pty(window_size.to_winsize())?;
 
     #[cfg(any(target_os = "linux", target_os = "macos"))]
@@ -178,13 +178,14 @@ pub fn new(config: &PtyConfig, window_size: WindowSize, window_id: Option<usize>
     builder.stdout(unsafe { Stdio::from_raw_fd(slave) });
 
     // Setup shell environment.
+    let window_id = window_id.to_string();
+    builder.env("ALACRITTY_WINDOW_ID", &window_id);
     builder.env("LOGNAME", pw.name);
     builder.env("USER", pw.name);
     builder.env("HOME", pw.dir);
 
-    if let Some(window_id) = window_id {
-        builder.env("WINDOWID", format!("{}", window_id));
-    }
+    // Set Window ID for clients relying on X11 hacks.
+    builder.env("WINDOWID", window_id);
 
     unsafe {
         builder.pre_exec(move || {
diff --git a/alacritty_terminal/src/tty/windows/mod.rs b/alacritty_terminal/src/tty/windows/mod.rs
index aa21ce14..57925f4c 100644
--- a/alacritty_terminal/src/tty/windows/mod.rs
+++ b/alacritty_terminal/src/tty/windows/mod.rs
@@ -27,7 +27,7 @@ pub struct Pty {
     child_watcher: ChildExitWatcher,
 }
 
-pub fn new(config: &PtyConfig, window_size: WindowSize, _window_id: Option<usize>) -> Result<Pty> {
+pub fn new(config: &PtyConfig, window_size: WindowSize, _window_id: u64) -> Result<Pty> {
     conpty::new(config, window_size)
         .ok_or_else(|| Error::new(ErrorKind::Other, "failed to spawn conpty"))
 }