Fix divide by zero bug

This fixes image-rs#33

src/decoder/mod.rs

@@ -612,6 +612,10 @@ impl<R: Read + Seek> Decoder<R> {
             .get_tag_u32(ifd::Tag::RowsPerStrip)
             .unwrap_or(self.height);
 
+        if rows_per_strip == 0 {
+            return Ok(0);
+        }
+
         Ok((self.height + rows_per_strip - 1) / rows_per_strip)
     }
 

tests/fuzz_tests.rs

@@ -40,3 +40,12 @@ fn inf_loop() {
         true
     });
 }
+
+// https://github.com/image-rs/image-tiff/issues/33
+#[test]
+fn divide_by_zero() {
+    test_directory("./tests/fuzz_images/divide_by_zero", |file| {
+        decode_tiff(file).ok();
+        true
+    });
+}