api: cffi: add dc_accounts_background_fetch_with_timeout

deltachat-ffi/deltachat.h

@@ -3151,6 +3151,20 @@ void           dc_accounts_maybe_network        (dc_accounts_t* accounts);
 void           dc_accounts_maybe_network_lost    (dc_accounts_t* accounts);
 
 
+/**
+ * Perform a Background fetch for all accounts in parallel with a timeout.
+ * Pauses the scheduler, fetches messages from imap and then resumes the scheduler.
+ *
+ * dc_accounts_background_fetch_with_timeout() was created for the iOS Background fetch.
+ *
+ * @memberof dc_accounts_t
+ * @param timeout The timeout in seconds
+ * @return Return 1 on success and 0 on failure (like timeout)
+ *    But note that this only indicates that the fetch of all accounts was done before the timeout.
+ *    To know wether it worked you need to look for the events.
+ */
+int            dc_accounts_background_fetch_with_timeout    (dc_accounts_t* accounts, uint64_t timeout);
+
 /**
  * Create the event emitter that is used to receive events.
  *

deltachat-ffi/src/lib.rs

@@ -4898,6 +4898,34 @@ pub unsafe extern "C" fn dc_accounts_maybe_network_lost(accounts: *mut dc_accoun
     block_on(async move { accounts.write().await.maybe_network_lost().await });
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_accounts_background_fetch_with_timeout(
+    accounts: *mut dc_accounts_t,
+    timeout_in_seconds: u64,
+) -> libc::c_int {
+    if accounts.is_null() || timeout_in_seconds <= 2 {
+        eprintln!("ignoring careless call to dc_accounts_background_fetch_with_timeout()");
+        return 0;
+    }
+
+    let accounts = &*accounts;
+    block_on(async move {
+        let accounts = accounts.write().await;
+        match accounts
+            .background_fetch_with_timeout(Duration::from_secs(timeout_in_seconds))
+            .await
+        {
+            Ok(()) => 1,
+            Err(err) => {
+                accounts.emit_event(EventType::Error(format!(
+                    "Failed to do background fetch: {err:#}"
+                )));
+                0
+            }
+        }
+    })
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_accounts_get_event_emitter(
     accounts: *mut dc_accounts_t,