Set env variables before window start

The environment variables specified in the configuration file are now
all set before the window is created. As a result, this makes it
possible to add the `WINIT_HIDPI_FACTOR` env variable directly to the
Alacritty configuration.

This fixes https://github.com/jwilm/alacritty/issues/1768.

4 files changed, 40 insertions, 19 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 32c678b0..15164698 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -45,6 +45,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Resizing of windows without decorations
 - On Wayland, key repetition works again
 - On macOS, Alacritty will now use the integrated GPU again when available
+- On Linux, the `WINIT_HIDPI_FACTOR` environment variable can be set from the config now
 
 ## Version 0.2.1
 
diff --git a/src/main.rs b/src/main.rs
index e72df15d..11adb396 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -116,6 +116,9 @@ fn run(mut config: Config, options: &cli::Options) -> Result<(), Box<Error>> {
         info!("Configuration loaded from {}", config_path.display());
     };
 
+    // Set environment variables
+    tty::setup_env(&config);
+
     // Create a display.
     //
     // The display manages a window and can draw the terminal
diff --git a/src/tty/mod.rs b/src/tty/mod.rs
index 5657b0fd..faed276d 100644
--- a/src/tty/mod.rs
+++ b/src/tty/mod.rs
@@ -13,9 +13,12 @@
 // limitations under the License.
 //
 //! tty related functionality
-
 use mio;
-use std::io;
+use std::{env, io};
+
+use terminfo::Database;
+
+use config::Config;
 
 #[cfg(not(windows))]
 mod unix;
@@ -34,7 +37,13 @@ pub trait EventedReadWrite {
     type Reader: io::Read;
     type Writer: io::Write;
 
-    fn register(&mut self, &mio::Poll, &mut Iterator<Item = &usize>, mio::Ready, mio::PollOpt) -> io::Result<()>;
+    fn register(
+        &mut self,
+        &mio::Poll,
+        &mut Iterator<Item = &usize>,
+        mio::Ready,
+        mio::PollOpt,
+    ) -> io::Result<()>;
     fn reregister(&mut self, &mio::Poll, mio::Ready, mio::PollOpt) -> io::Result<()>;
     fn deregister(&mut self, &mio::Poll) -> io::Result<()>;
 
@@ -43,3 +52,26 @@ pub trait EventedReadWrite {
     fn writer(&mut self) -> &mut Self::Writer;
     fn write_token(&self) -> mio::Token;
 }
+
+// Setup environment variables
+pub fn setup_env(config: &Config) {
+    // Default to 'alacritty' terminfo if it is available, otherwise
+    // default to 'xterm-256color'. May be overridden by user's config
+    // below.
+    env::set_var(
+        "TERM",
+        if Database::from_name("alacritty").is_ok() {
+            "alacritty"
+        } else {
+            "xterm-256color"
+        },
+    );
+
+    // Advertise 24-bit color support
+    env::set_var("COLORTERM", "truecolor");
+
+    // Set env vars from config
+    for (key, value) in config.env().iter() {
+        env::set_var(key, value);
+    }
+}
diff --git a/src/tty/unix.rs b/src/tty/unix.rs
index 08a2c4f3..d6ab6a46 100644
--- a/src/tty/unix.rs
+++ b/src/tty/unix.rs
@@ -23,7 +23,6 @@ use cli::Options;
 use mio;
 
 use libc::{self, c_int, pid_t, winsize, SIGCHLD, TIOCSCTTY, WNOHANG};
-use terminfo::Database;
 
 use std::os::unix::io::{FromRawFd, RawFd};
 use std::fs::File;
@@ -241,29 +240,15 @@ pub fn new<T: ToWinsize>(
     builder.stderr(unsafe { Stdio::from_raw_fd(slave) });
     builder.stdout(unsafe { Stdio::from_raw_fd(slave) });
 
-    // Setup environment
+    // Setup shell environment
     builder.env("LOGNAME", pw.name);
     builder.env("USER", pw.name);
     builder.env("SHELL", shell.program());
     builder.env("HOME", pw.dir);
 
-    // TERM; default to 'alacritty' if it is available, otherwise
-    // default to 'xterm-256color'. May be overridden by user's config
-    // below.
-    let term = if Database::from_name("alacritty").is_ok() {
-        "alacritty"
-    } else {
-        "xterm-256color"
-    };
-    builder.env("TERM", term);
-
-    builder.env("COLORTERM", "truecolor"); // advertise 24-bit support
     if let Some(window_id) = window_id {
         builder.env("WINDOWID", format!("{}", window_id));
     }
-    for (key, value) in config.env().iter() {
-        builder.env(key, value);
-    }
 
     builder.before_exec(move || {
         // Create a new process group