Test if CString is empty before calling C API

Author: yogh333

ledger_device_sdk/src/nbgl/nbgl_address_review.rs

@@ -12,7 +12,7 @@ impl SyncNBGL for NbglAddressReview<'_> {}
 impl<'a> NbglAddressReview<'a> {
     pub fn new() -> NbglAddressReview<'a> {
         NbglAddressReview {
-            verify_str: CString::new("").unwrap(),
+            verify_str: CString::default(),
             glyph: None,
         }
     }
@@ -45,7 +45,10 @@ impl<'a> NbglAddressReview<'a> {
                 address.as_ptr(),
                 core::ptr::null(),
                 &icon as *const nbgl_icon_details_t,
-                self.verify_str.as_ptr(),
+                match self.verify_str.is_empty() {
+                    true => core::ptr::null(),
+                    false => self.verify_str.as_ptr()
+                },
                 core::ptr::null(),
                 Some(choice_callback),
             );

ledger_device_sdk/src/nbgl/nbgl_review.rs

@@ -17,9 +17,9 @@ impl SyncNBGL for NbglReview<'_> {}
 impl<'a> NbglReview<'a> {
     pub fn new() -> NbglReview<'a> {
         NbglReview {
-            title: CString::new("").unwrap(),
-            subtitle: CString::new("").unwrap(),
-            finish_title: CString::new("").unwrap(),
+            title: CString::default(),
+            subtitle: CString::default(),
+            finish_title: CString::default(),
             glyph: None,
             tx_type: TransactionType::Transaction,
             blind: false,
@@ -130,9 +130,18 @@ impl<'a> NbglReview<'a> {
                             self.tx_type.to_c_type(false),
                             &tag_value_list as *const nbgl_contentTagValueList_t,
                             &icon as *const nbgl_icon_details_t,
-                            self.title.as_ptr() as *const c_char,
-                            self.subtitle.as_ptr() as *const c_char,
-                            self.finish_title.as_ptr() as *const c_char,
+                            match self.title.is_empty() {
+                                true => core::ptr::null(),
+                                false => self.title.as_ptr() as *const c_char
+                            },
+                            match self.subtitle.is_empty() {
+                                true => core::ptr::null(),
+                                false => self.subtitle.as_ptr() as *const c_char
+                            },
+                            match self.finish_title.is_empty() {
+                                true => core::ptr::null(),
+                                false => self.finish_title.as_ptr() as *const c_char
+                            },
                             Some(choice_callback),
                         );
                     }