feat(theme): themes as files (theme crate: toml subset + ints, contrast check, wire); whimsy dark + light; display reads themes/, serves THEME/THEME_NAME, init SET_THEME -> THEME_CHANGED to all windows, bar themed; k-ui follows; settings appearance; init keeps choice in sealed users/<id>/settings/, reapplies at sign-in + display restart

crates/bins/display-qemu/src/main.rs

@@ -9,6 +9,12 @@ use types::bounded::CapSlot;
 /// Where init put them (see init's manifest: own endpoint, then `uses`).
 const EP: CapSlot = CapSlot::const_new(0);
 const INPUT: CapSlot = CapSlot::const_new(1);
+/// `themes/`, read-only.
+const THEMES: CapSlot = CapSlot::const_new(2);
+/// Where storage's buffer is mapped while the themes are read.
+const STORAGE_BUF_VA: types::address::VirtualAddress = types::address::VirtualAddress::from_raw(0x0180_0000);
+/// The longest theme file read.
+const THEME_BYTES: usize = 4096;
 
 libkos::entry!(main);
 
@@ -38,7 +44,47 @@ fn subscribe_to_input() -> Option<CapSlot> {
 }
 
 fn server<F: port_framebuffer::Framebuffer>(fb: F, input: Option<CapSlot>) -> display_server::server::DisplayServer<F, display_server::host::KernelHost> {
-    display_server::server::DisplayServer::new(fb, display_server::host::KernelHost::new(EP, input))
+    display_server::server::DisplayServer::new(fb, display_server::host::KernelHost::new(EP, input), themes())
+}
+
+/// Every theme in `themes/` that reads and passes contrast; the built-in
+/// one if none does.
+fn themes() -> display_server::themes::Themes {
+    let mut themes = display_server::themes::Themes::new();
+    let Ok(mut fs) = libkos::fs::Storage::attach(THEMES, STORAGE_BUF_VA) else {
+        libkos::println!("display: no themes folder; the built-in theme only");
+        return themes;
+    };
+    let mut names = [([0u8; types::storage::DIR_NAME_SIZE], 0usize); display_server::themes::MAX_THEMES];
+    let mut found = 0;
+    let _ = fs.list_dir(b"", |e| {
+        if !e.is_dir && e.name().ends_with(b".toml") && found < names.len() {
+            names[found] = (e.name, e.name_len);
+            found += 1;
+        }
+    });
+    let mut text = [0u8; THEME_BYTES];
+    for (name, len) in &names[..found] {
+        let name = &name[..*len];
+        let read = fs.open(name).and_then(|h| {
+            let n = fs.read(h, &mut text);
+            let _ = fs.close(h);
+            n
+        });
+        let shown = core::str::from_utf8(name).unwrap_or("?");
+        match read.ok().and_then(|n| core::str::from_utf8(&text[..n]).ok()) {
+            Some(t) => {
+                if let Err(e) = themes.add(t) {
+                    libkos::println!("display: theme {} refused: {:?}", shown, e);
+                }
+            }
+            None => libkos::println!("display: cannot read theme {}", shown),
+        }
+    }
+    fs.detach();
+    // Storage has few connections to give; this one is done with.
+    let _ = libkos::fs::release(THEMES);
+    themes
 }
 
 #[inline(never)]