font_collection_num_fonts_overflow test fails on 32-bit architectures about ttf-parser HOT 3 OPEN

Can confirm.

from ttf-parser.

The issue is that the code takes a 32-bit number, converts it to a usize and then multiplies it by SIZE. Afaict SIZE is always a small number so on 64-bit systems this can never overflow. However on 32-bit systems it can and does overflow.

The change below makes the test pass, but I'd like some feedback whether this is the correct approach before I go and add it as a distribution patch.

     pub fn read_array32<T: FromData>(&mut self, count: u32) -> Option<LazyArray
-        let len = usize::num_from(count) * T::SIZE;
-        self.read_bytes(len).map(LazyArray32::new)
+        if let Some(len) = usize::num_from(count).checked_mul(T::SIZE) {
+            self.read_bytes(len).map(LazyArray32::new)
+        } else {
+            None
+        }
     }

from ttf-parser.

@plugwash yes, I know that this is because usize is 32bit here, but I want a global solution and not a local one. Will think about it.

from ttf-parser.