translations: Use gnome-desktop's xkb info database for layout names

src/locale.rs

@@ -1,24 +1,93 @@
-/*! Locale-specific functions */
+/*! Locale-specific functions. */
 
 use std::cmp;
-use std::ffi::CString;
+use std::ffi::{ CStr, CString };
+use std::os::raw::c_char;
+use std::ptr;
+use std::str::Utf8Error;
 
 mod c {
-    use std::os::raw::c_char;
+    use super::*;
+    use std::os::raw::c_void;
 
     #[allow(non_camel_case_types)]
     pub type c_int = i32;
 
+    #[derive(Clone, Copy)]
+    #[repr(C)]
+    pub struct GnomeXkbInfo(*const c_void);
+
     #[no_mangle]
     extern "C" {
         // from libc
         pub fn strcoll(cs: *const c_char, ct: *const c_char) -> c_int;
+        // from gnome-desktop3
+        pub fn gnome_xkb_info_new() -> GnomeXkbInfo;
+        pub fn gnome_xkb_info_get_layout_info (
+            info: GnomeXkbInfo,
+            id: *const c_char,
+            display_name: *mut *const c_char,
+            short_name: *const *const c_char,
+            xkb_layout: *const *const c_char,
+            xkb_variant: *const *const c_char
+        ) -> c_int;
+        pub fn g_object_unref(o: GnomeXkbInfo);
+    }
+}
+
+#[derive(Debug)]
+pub enum Error {
+    StringConversion(Utf8Error),
+    NoInfo,
+}
+
+pub struct XkbInfo(c::GnomeXkbInfo);
+
+impl XkbInfo {
+    pub fn new() -> XkbInfo {
+        XkbInfo(unsafe { c::gnome_xkb_info_new() })
+    }
+    pub fn get_display_name(&self, id: &str) -> Result<String, Error> {
+        let id = cstring_safe(id);
+        let id_ref = id.as_ptr();
+        let mut display_name: *const c_char = ptr::null();
+        let found = unsafe {
+            c::gnome_xkb_info_get_layout_info(
+                self.0,
+                id_ref,
+                &mut display_name as *mut *const c_char,
+                ptr::null(), ptr::null(), ptr::null(),
+            )
+        };
+        if found != 0 && !display_name.is_null() {
+            let display_name = unsafe { CStr::from_ptr(display_name) };
+            display_name.to_str()
+                .map(str::to_string)
+                .map_err(Error::StringConversion)
+        } else {
+            Err(Error::NoInfo)
+        }
+    }
+}
+
+impl Drop for XkbInfo {
+    fn drop(&mut self) {
+        unsafe { c::g_object_unref(self.0) }
     }
 }
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct Translation<'a>(pub &'a str);
 
+impl<'a> Translation<'a> {
+    pub fn to_owned(&'a self) -> OwnedTranslation {
+        OwnedTranslation(self.0.to_owned())
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct OwnedTranslation(pub String);
+
 fn cstring_safe(s: &str) -> CString {
     CString::new(s)
         .unwrap_or(CString::new("").unwrap())