add dc_has_device_msg()

deltachat-ffi/deltachat.h

@@ -1171,6 +1171,21 @@ uint32_t        dc_add_device_msg_unlabelled(dc_context_t* context, dc_msg_t* ms
 void            dc_skip_device_msg           (dc_context_t* context, const char* label);
 
 
+
+/**
+ * Check if a device-message was ever added or skipped.
+ * Device-messages can be added or skipped
+ * using dc_add_device_msg_once() or dc_skip_device_msg().
+ *
+ * @memberof dc_context_t
+ * @param context The context as created by dc_context_new().
+ * @param label Label of the message to check.
+ * @return 1=A message with this label was added or skipped at some point,
+ *     0=A message with this label was never added nor skipped.
+ */
+int             dc_has_device_msg            (dc_context_t* context, const char* label);
+
+
 /**
  * Get draft for a chat, if any.
  * See dc_set_draft() for more details about drafts.

deltachat-ffi/src/lib.rs

@@ -870,6 +870,23 @@ pub unsafe extern "C" fn dc_skip_device_msg(
         .unwrap_or(())
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_has_device_msg(
+    context: *mut dc_context_t,
+    label: *const libc::c_char,
+) -> libc::c_int {
+    if context.is_null() || label.is_null() {
+        eprintln!("ignoring careless call to dc_has_device_msg()");
+        return 0;
+    }
+    let ffi_context = &mut *context;
+    ffi_context
+        .with_inner(|ctx| {
+            chat::has_device_msg(ctx, &to_string_lossy(label)).unwrap_or(false) as libc::c_int
+        })
+        .unwrap_or(0)
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_get_draft(context: *mut dc_context_t, chat_id: u32) -> *mut dc_msg_t {
     if context.is_null() {

src/chat.rs

@@ -2021,12 +2021,7 @@ fn add_device_msg_maybe_labelled(
 }
 
 pub fn skip_device_msg(context: &Context, label: &str) -> Result<(), Error> {
-    ensure!(!label.is_empty(), "cannot skip empty label");
-    if let Ok(()) = context.sql.query_row(
-        "SELECT label FROM devmsglabels WHERE label=?",
-        params![label],
-        |_| Ok(()),
-    ) {
+    if has_device_msg(context, label)? {
         info!(context, "device-message {} already added", label);
         return Ok(());
     }
@@ -2039,6 +2034,19 @@ pub fn skip_device_msg(context: &Context, label: &str) -> Result<(), Error> {
     Ok(())
 }
 
+pub fn has_device_msg(context: &Context, label: &str) -> Result<bool, Error> {
+    ensure!(!label.is_empty(), "empty label");
+    if let Ok(()) = context.sql.query_row(
+        "SELECT label FROM devmsglabels WHERE label=?",
+        params![label],
+        |_| Ok(()),
+    ) {
+        return Ok(true);
+    }
+
+    Ok(false)
+}
+
 pub fn add_info_msg(context: &Context, chat_id: u32, text: impl AsRef<str>) {
     let rfc724_mid = dc_create_outgoing_rfc724_mid(None, "@device");
 
@@ -2251,6 +2259,22 @@ mod tests {
         assert!(!msg_id.as_ref().unwrap().is_unset());
     }
 
+    #[test]
+    fn test_has_device_msg() {
+        let t = test_context(Some(Box::new(logging_cb)));
+        skip_device_msg(&t.ctx, "some-label").ok();
+        assert!(has_device_msg(&t.ctx, "some-label").unwrap());
+
+        let mut msg = Message::new(Viewtype::Text);
+        msg.text = Some("message text".to_string());
+        add_device_msg_once(&t.ctx, "another-label", &mut msg).ok();
+        assert!(has_device_msg(&t.ctx, "another-label").unwrap());
+
+        assert!(!has_device_msg(&t.ctx, "unused-label").unwrap());
+
+        assert!(has_device_msg(&t.ctx, "").is_err());
+    }
+
     fn chatlist_len(ctx: &Context, listflags: usize) -> usize {
         Chatlist::try_load(ctx, listflags, None, None)
             .unwrap()