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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use nserror::nsresult;
use nsstring::nsCString;
use xpcom::{
get_service,
interfaces::{
nsIMsgIncomingServer, nsIMsgOutgoingServer, nsIObserver, nsIPrefBranch, nsIPrefService,
},
RefPtr, XpCom,
};
/// A server on which an observer can subscribe to changes.
pub(crate) trait ObservableServer {
/// Registers an `nsIObserver` to be called when a given property of the
/// server changes.
fn observe_property(
&self,
pref_name: &str,
observer: RefPtr<nsIObserver>,
) -> Result<(), nsresult>;
/// Registers an `nsIObserver` to be called on changes to a preference or
/// branch.
///
/// If `name` ends with a trailing `.`, it refers to a branch, and the
/// observer is subscribed to any change to a property in that branch.
fn register_observer(name: String, observer: RefPtr<nsIObserver>) -> Result<(), nsresult> {
let pref_svc = get_service::<nsIPrefService>(c"@mozilla.org/preferences-service;1")
.ok_or(nserror::NS_ERROR_FAILURE)?;
// The underlying implementation of `nsIPrefService` also implements
// `nsIPrefBranch`. While this relationship isn't strictly specified or
// explictly documented in the XPIDL files, most JS services rely on it
// (through e.g. `Services.prefs.get[...]Pref`) so it should be safe to
// rely on this here too.
//
// Using the "root" pref branch here means the consumer does not need to
// hold on to a reference to an `nsIPrefBranch` instance. This would
// have been necessary otherwise because independent `nsIPrefBranch`
// instances clear their observer list upon getting dropped. The one
// we're getting here is special, because it's actually the preferences
// service which is always around.
let pref_branch = pref_svc
.query_interface::<nsIPrefBranch>()
.ok_or(nserror::NS_ERROR_FAILURE)?;
let pref_name = nsCString::from(name);
unsafe { pref_branch.AddObserverImpl(&*pref_name, observer.coerce(), false) }.to_result()
}
}
impl ObservableServer for nsIMsgIncomingServer {
fn observe_property(
&self,
pref_name: &str,
observer: RefPtr<nsIObserver>,
) -> Result<(), nsresult> {
let mut key = nsCString::new();
unsafe { self.GetKey(&mut *key) }.to_result()?;
let pref_name = format!("mail.server.{key}.{pref_name}");
Self::register_observer(pref_name, observer)
}
}
impl ObservableServer for nsIMsgOutgoingServer {
fn observe_property(
&self,
pref_name: &str,
observer: RefPtr<nsIObserver>,
) -> Result<(), nsresult> {
let mut key = nsCString::new();
unsafe { self.GetKey(&mut *key) }.to_result()?;
let pref_name = format!("mail.outgoingserver.{key}.{pref_name}");
Self::register_observer(pref_name, observer)
}
}