Initial commit

breadgreet/src/sessions.rs

@@ -0,0 +1,94 @@
+//! Session discovery: scans the standard greetd-greeter session directories
+//! for `.desktop` entries. BOS effectively ships one session (Hyprland via
+//! `bos-session`), so v1 has no picker UI — it just auto-selects the
+//! configured default (or the only entry found) and resolves its `Exec=`
+//! line to hand to `greetd`'s `StartSession`.
+
+use breadlock_ui::desktop_entry::{scan_dir, DesktopEntry};
+use std::path::Path;
+
+pub struct Session {
+    pub name: String,
+    pub exec: Vec<String>,
+}
+
+/// Scans `wayland_dirs` then `xsessions_dirs` (in that order) and returns
+/// the entry matching `default` (by `.desktop` file stem), falling back to
+/// the first entry found in either directory. `None` if nothing is
+/// installed — the greeter has no session to offer.
+pub fn discover(
+    wayland_dirs: &[String],
+    xsessions_dirs: &[String],
+    default: &str,
+) -> Option<Session> {
+    let mut all: Vec<(String, DesktopEntry)> = Vec::new();
+    for dir in wayland_dirs.iter().chain(xsessions_dirs) {
+        all.extend(scan_dir(Path::new(dir)));
+    }
+
+    let chosen = all
+        .iter()
+        .find(|(stem, _)| stem == default)
+        .or_else(|| all.first())?;
+
+    Some(Session {
+        name: chosen.1.name.clone(),
+        exec: split_exec(&chosen.1.exec),
+    })
+}
+
+/// Splits a `.desktop` `Exec=` line into an argv. Only handles plain
+/// whitespace-separated commands (BOS's own `hyprland.desktop` is
+/// `Exec=Hyprland`) — full field-code (`%f`, `%u`, …) and quoting support
+/// isn't needed for a greeter that never launches file-manager-style
+/// entries.
+fn split_exec(exec: &str) -> Vec<String> {
+    exec.split_whitespace()
+        .filter(|arg| !arg.starts_with('%'))
+        .map(str::to_string)
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn split_exec_drops_field_codes() {
+        assert_eq!(split_exec("Hyprland"), vec!["Hyprland"]);
+        assert_eq!(split_exec("gnome-session %U"), vec!["gnome-session"]);
+    }
+
+    #[test]
+    fn discover_returns_none_when_no_directories_exist() {
+        assert!(discover(
+            &["/nonexistent/a".to_string()],
+            &["/nonexistent/b".to_string()],
+            "hyprland"
+        )
+        .is_none());
+    }
+
+    #[test]
+    fn discover_prefers_configured_default_over_first_entry() {
+        let dir = std::env::temp_dir().join("breadgreet-test-sessions-discover");
+        std::fs::create_dir_all(&dir).unwrap();
+        std::fs::write(
+            dir.join("aaa.desktop"),
+            "[Desktop Entry]\nName=A\nExec=a-cmd\n",
+        )
+        .unwrap();
+        std::fs::write(
+            dir.join("hyprland.desktop"),
+            "[Desktop Entry]\nName=Hyprland\nExec=Hyprland\n",
+        )
+        .unwrap();
+
+        let dir_str = dir.to_str().unwrap().to_string();
+        let session = discover(&[dir_str], &[], "hyprland").unwrap();
+        assert_eq!(session.name, "Hyprland");
+        assert_eq!(session.exec, vec!["Hyprland"]);
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+}