Merge pull request #548 from Enet4/bug/parser/547-item-header-out-seq…

…uence [parser] Turn illegal item header parse into recoverable error
Enet4 · Jul 28, 2024 · af18fbe · af18fbe
2 parents dba0412 + ff98911
commit af18fbe
Showing 1 changed file with 60 additions and 3 deletions.
diff --git a/parser/src/dataset/read.rs b/parser/src/dataset/read.rs
@@ -64,6 +64,14 @@ pub enum Error {
     },
     #[snafu(display("Unexpected item tag {} while reading element header", tag))]
     UnexpectedItemTag { tag: Tag, backtrace: Backtrace },
+    #[snafu(display(
+        "Unexpected item header outside a dataset sequence at {} bytes",
+        bytes_read
+    ))]
+    UnexpectedItemHeader {
+        bytes_read: u64,
+        backtrace: Backtrace,
+    },
     /// Undefined pixel item length
     UndefinedItemLength,
 }
@@ -277,12 +285,23 @@ where
                         SequenceItemHeader::Item { len } => {
                             // entered a new item
                             self.in_sequence = false;
+
+                            let last_delimiter = match self.seq_delimiters.last() {
+                                Some(d) => d,
+                                None => {
+                                    return Some(
+                                        UnexpectedItemHeaderSnafu {
+                                            bytes_read: self.parser.position(),
+                                        }
+                                        .fail(),
+                                    )
+                                }
+                            };
                             self.push_sequence_token(
                                 SeqTokenType::Item,
                                 len,
-                                self.seq_delimiters.last()
-                                    .expect("item header should be read only inside an existing sequence")
-                                    .pixel_data);
+                                last_delimiter.pixel_data,
+                            );
                             // items can be empty
                             if len == Length(0) {
                                 self.delimiter_check_pending = true;
@@ -1224,4 +1243,42 @@ mod tests {
         // finished reading, peek should return None
         assert!(iter.peek().unwrap().is_none());
     }
+
+    #[test]
+    fn read_pixel_sequence_bad_item_end() {
+        #[rustfmt::skip]
+        static DATA: &[u8] = &[
+            0xe0, 0x7f, 0x10, 0x00, // (7FE0, 0010) PixelData
+            b'O', b'B', // VR 
+            0x00, 0x00, // reserved
+            0xff, 0xff, 0xff, 0xff, // length: undefined
+            // -- 12 --
+            0xfe, 0xff, 0x00, 0xe0, // item start tag
+            0x00, 0x00, 0x00, 0x00, // item length: 0
+            // -- 20 --
+            0xfe, 0xff, 0x0d, 0xe0, // item end
+            0x00, 0x00, 0x00, 0x00, // length is always zero
+            // -- 28 --
+            0xfe, 0xff, 0x0d, 0xe0, // another item end (bad)
+            0x00, 0x00, 0x00, 0x00, //
+            // -- 36 --
+            0xfe, 0xff, 0x00, 0xe0, // another item start
+            0x00, 0x00, 0x00, 0x00, // item length: 0
+        ];
+
+        let mut cursor = DATA;
+        let parser = StatefulDecoder::new(
+            &mut cursor,
+            ExplicitVRLittleEndianDecoder::default(),
+            LittleEndianBasicDecoder::default(),
+            SpecificCharacterSet::default(),
+        );
+        let mut dset_reader = DataSetReader::new(parser, Default::default());
+
+        let token_res = (&mut dset_reader)
+            .into_iter()
+            .collect::<Result<Vec<_>, _>>();
+        dbg!(&token_res);
+        assert!(token_res.is_err());
+    }
 }