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.

7 files changed, 35 insertions, 14 deletions

diff --git a/alacritty_terminal/Cargo.toml b/alacritty_terminal/Cargo.toml
index fb5d2d22..06d3961a 100644
--- a/alacritty_terminal/Cargo.toml
+++ b/alacritty_terminal/Cargo.toml
@@ -13,6 +13,10 @@ rust-version = "1.57.0"
 path = "../alacritty_config_derive"
 version = "0.1.0"
 
+[dependencies.alacritty_config]
+path = "../alacritty_config"
+version = "0.1.0"
+
 [dependencies]
 libc = "0.2"
 bitflags = "1"
diff --git a/alacritty_terminal/src/config/mod.rs b/alacritty_terminal/src/config/mod.rs
index 5822d591..53a0eb77 100644
--- a/alacritty_terminal/src/config/mod.rs
+++ b/alacritty_terminal/src/config/mod.rs
@@ -4,7 +4,7 @@ use std::path::PathBuf;
 
 use serde::Deserialize;
 
-use alacritty_config_derive::ConfigDeserialize;
+use alacritty_config_derive::{ConfigDeserialize, SerdeReplace};
 
 mod scrolling;
 
@@ -17,7 +17,7 @@ pub const LOG_TARGET_CONFIG: &str = "alacritty_config_derive";
 const MIN_BLINK_INTERVAL: u64 = 10;
 
 /// Top-level config type.
-#[derive(ConfigDeserialize, Debug, PartialEq, Default)]
+#[derive(ConfigDeserialize, Clone, Debug, PartialEq, Default)]
 pub struct Config {
     /// TERM env variable.
     pub env: HashMap<String, String>,
@@ -125,7 +125,7 @@ impl Cursor {
     }
 }
 
-#[derive(Deserialize, Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(SerdeReplace, Deserialize, Debug, Copy, Clone, PartialEq, Eq)]
 #[serde(untagged)]
 pub enum ConfigCursorStyle {
     Shape(CursorShape),
@@ -222,7 +222,7 @@ impl Program {
 }
 
 /// Wrapper around f32 that represents a percentage value between 0.0 and 1.0.
-#[derive(Deserialize, Clone, Copy, Debug, PartialEq)]
+#[derive(SerdeReplace, Deserialize, Clone, Copy, Debug, PartialEq)]
 pub struct Percentage(f32);
 
 impl Default for Percentage {
diff --git a/alacritty_terminal/src/config/scrolling.rs b/alacritty_terminal/src/config/scrolling.rs
index 9a5a718c..f4e55787 100644
--- a/alacritty_terminal/src/config/scrolling.rs
+++ b/alacritty_terminal/src/config/scrolling.rs
@@ -1,7 +1,7 @@
 use serde::de::Error as SerdeError;
 use serde::{Deserialize, Deserializer};
 
-use alacritty_config_derive::ConfigDeserialize;
+use alacritty_config_derive::{ConfigDeserialize, SerdeReplace};
 
 /// Maximum scrollback amount configurable.
 pub const MAX_SCROLLBACK_LINES: u32 = 100_000;
@@ -31,7 +31,7 @@ impl Scrolling {
     }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(SerdeReplace, Copy, Clone, Debug, PartialEq, Eq)]
 struct ScrollingHistory(u32);
 
 impl Default for ScrollingHistory {
diff --git a/alacritty_terminal/src/index.rs b/alacritty_terminal/src/index.rs
index e672c752..9464b8d8 100644
--- a/alacritty_terminal/src/index.rs
+++ b/alacritty_terminal/src/index.rs
@@ -7,6 +7,8 @@ use std::ops::{Add, AddAssign, Deref, Sub, SubAssign};
 
 use serde::{Deserialize, Serialize};
 
+use alacritty_config_derive::SerdeReplace;
+
 use crate::grid::Dimensions;
 
 /// The side of a cell.
@@ -222,7 +224,19 @@ impl PartialEq<usize> for Line {
 /// A column.
 ///
 /// Newtype to avoid passing values incorrectly.
-#[derive(Serialize, Deserialize, Debug, Copy, Clone, Eq, PartialEq, Default, Ord, PartialOrd)]
+#[derive(
+    SerdeReplace,
+    Serialize,
+    Deserialize,
+    Debug,
+    Copy,
+    Clone,
+    Eq,
+    PartialEq,
+    Default,
+    Ord,
+    PartialOrd,
+)]
 pub struct Column(pub usize);
 
 impl fmt::Display for Column {
diff --git a/alacritty_terminal/src/term/color.rs b/alacritty_terminal/src/term/color.rs
index 1cfdec6b..3c545b28 100644
--- a/alacritty_terminal/src/term/color.rs
+++ b/alacritty_terminal/src/term/color.rs
@@ -7,12 +7,14 @@ use serde::de::{Error as _, Visitor};
 use serde::{Deserialize, Deserializer, Serialize};
 use serde_yaml::Value;
 
+use alacritty_config_derive::SerdeReplace;
+
 use crate::ansi::NamedColor;
 
 /// Number of terminal colors.
 pub const COUNT: usize = 269;
 
-#[derive(Debug, Eq, PartialEq, Copy, Clone, Default, Serialize)]
+#[derive(SerdeReplace, Debug, Eq, PartialEq, Copy, Clone, Default, Serialize)]
 pub struct Rgb {
     pub r: u8,
     pub g: u8,
@@ -170,7 +172,7 @@ impl FromStr for Rgb {
 }
 
 /// RGB color optionally referencing the cell's foreground or background.
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(SerdeReplace, Copy, Clone, Debug, PartialEq, Eq)]
 pub enum CellRgb {
     CellForeground,
     CellBackground,
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"))
 }