Music app : when title/track name are truncated, add an ellipsis at the end of the strings.

src/components/ble/MusicService.cpp

@@ -17,6 +17,7 @@
 */
 #include "components/ble/MusicService.h"
 #include "systemtask/SystemTask.h"
+#include <cstring>
 
 namespace {
   // 0000yyxx-78fc-48fe-8e23-433b3a1942d0
@@ -47,6 +48,8 @@ namespace {
   constexpr ble_uuid128_t msRepeatCharUuid {CharUuid(0x0b, 0x00)};
   constexpr ble_uuid128_t msShuffleCharUuid {CharUuid(0x0c, 0x00)};
 
+  constexpr uint8_t MaxStringSize {40};
+
   int MusicCallback(uint16_t conn_handle, uint16_t attr_handle, struct ble_gatt_access_ctxt* ctxt, void* arg) {
     return static_cast<Pinetime::Controllers::MusicService*>(arg)->OnCommand(conn_handle, attr_handle, ctxt);
   }
@@ -125,9 +128,21 @@ void Pinetime::Controllers::MusicService::Init() {
 int Pinetime::Controllers::MusicService::OnCommand(uint16_t conn_handle, uint16_t attr_handle, struct ble_gatt_access_ctxt* ctxt) {
   if (ctxt->op == BLE_GATT_ACCESS_OP_WRITE_CHR) {
     size_t notifSize = OS_MBUF_PKTLEN(ctxt->om);
-    char data[notifSize + 1];
-    data[notifSize] = '\0';
-    os_mbuf_copydata(ctxt->om, 0, notifSize, data);
+    size_t bufferSize = notifSize;
+    if (notifSize > MaxStringSize) {
+      bufferSize = MaxStringSize;
+    }
+
+    char data[bufferSize + 1];
+    os_mbuf_copydata(ctxt->om, 0, bufferSize, data);
+
+    if (notifSize > bufferSize) {
+      data[bufferSize-1] = '.';
+      data[bufferSize-2] = '.';
+      data[bufferSize-3] = '.';
+    }
+    data[bufferSize] = '\0';
+
     char* s = &data[0];
     if (ble_uuid_cmp(ctxt->chr->uuid, &msArtistCharUuid.u) == 0) {
       artistName = s;