Fix WARC headers parsing when record has Content-Length: 0 and reco…

…rd after it. (#42)

Validated against Python implementation: https://github.com/webrecorder/warcio

Also fixed flaky test `record::verify_display` by sorting header names in the test.

src/record.rs

@@ -1046,24 +1046,36 @@ mod raw_tests {
 
     #[test]
     fn verify_display() {
+        let header_entries = vec![
+            (WarcHeader::WarcType, b"dunno".to_vec()),
+            (WarcHeader::Date, b"2024-01-01T00:00:00Z".to_vec()),
+        ];
+
         let headers = RawRecordHeader {
             version: "1.0".to_owned(),
-            headers: vec![
-                (WarcHeader::WarcType, b"dunno".to_vec()),
-                (WarcHeader::Date, b"2024-01-01T00:00:00Z".to_vec()),
-            ]
-            .into_iter()
-            .collect(),
+            headers: header_entries.into_iter().collect(),
         };
 
-        let expected = "\
-            WARC/1.0\n\
-            warc-type: dunno\n\
-            warc-date: 2024-01-01T00:00:00Z\n\
-            \n\
-        ";
+        let output = headers.to_string();
+
+        let expected_lines = vec![
+            "WARC/1.0",
+            "warc-type: dunno",
+            "warc-date: 2024-01-01T00:00:00Z",
+            "",
+        ];
+        let actual_lines: Vec<_> = output.lines().collect();
+
+        let mut expected_headers: Vec<_> = expected_lines[1..expected_lines.len() - 1].to_vec();
+        expected_headers.sort();
+
+        let mut actual_headers: Vec<_> = actual_lines[1..actual_lines.len() - 1].to_vec();
+        actual_headers.sort();
 
-        assert_eq!(headers.to_string(), expected);
+        // verify parts
+        assert_eq!(actual_lines[0], expected_lines[0]); // WARC version
+        assert_eq!(actual_headers, expected_headers); // headers (sorted)
+        assert_eq!(actual_lines.last(), expected_lines.last()); // empty line
     }
 }
 

src/warc_reader.rs

@@ -120,7 +120,7 @@ impl<R: BufRead> Iterator for RawRecordIter<R> {
         let expected_body_len = headers_parsed.2;
 
         let mut body_buffer: Vec<u8> = Vec::with_capacity(1 * MB);
-        let mut found_body = expected_body_len == 0;
+        let mut found_body = false;
         let mut body_bytes_read = 0;
         let maximum_read_range = expected_body_len + 4;
         while !found_body {
@@ -203,7 +203,7 @@ impl<R: BufRead> Iterator for RecordIter<R> {
         let expected_body_len = headers_parsed.2;
 
         let mut body_buffer: Vec<u8> = Vec::with_capacity(1 * MB);
-        let mut found_body = expected_body_len == 0;
+        let mut found_body = false;
         let mut body_bytes_read = 0;
         let maximum_read_range = expected_body_len + 4;
         while !found_body {
@@ -683,4 +683,74 @@ mod next_item_tests {
             assert_eq!(record.body(), b"12345678");
         }
     }
+
+    #[test]
+    fn empty_content_length() {
+        let raw = b"\
+        WARC/1.0\r\n\
+        Warc-Type: empty-record\r\n\
+        Content-Length: 0\r\n\
+        WARC-Record-Id: <urn:test:empty-content-length>\r\n\
+        WARC-Date: 2020-07-08T02:52:57Z\r\n\
+        \r\n\
+        \r\n\
+    ";
+
+        let mut reader = WarcReader::new(create_reader!(raw));
+        let mut stream_iter = reader.stream_records();
+
+        let record = stream_iter
+            .next_item()
+            .unwrap()
+            .unwrap()
+            .into_buffered()
+            .unwrap();
+        assert_eq!(record.warc_version(), "1.0");
+        assert_eq!(record.content_length(), 0);
+        assert_eq!(record.warc_id(), "<urn:test:empty-content-length>");
+        assert_eq!(record.body(), b"");
+    }
+
+    #[test]
+    fn zero_and_nonzero_content_length() {
+        let raw = b"\
+        WARC/1.0\r\n\
+        Warc-Type: empty-record\r\n\
+        Content-Length: 0\r\n\
+        WARC-Record-Id: <urn:test:zero-content-length>\r\n\
+        WARC-Date: 2020-07-08T02:52:57Z\r\n\
+        \r\n\
+        \r\n\
+        \r\n\
+        WARC/1.0\r\n\
+        Warc-Type: non-empty-record\r\n\
+        Content-Length: 7\r\n\
+        WARC-Record-Id: <urn:test:nonzero-content-length>\r\n\
+        WARC-Date: 2020-07-08T02:52:58Z\r\n\
+        \r\n\
+        1234567\r\n\
+        \r\n\
+    ";
+
+        let reader = WarcReader::new(create_reader!(raw));
+        let mut iter = reader.iter_records();
+
+        // Test the first record with Content-Length: 0
+        {
+            let record = iter.next().unwrap().unwrap();
+            assert_eq!(record.warc_version(), "1.0");
+            assert_eq!(record.content_length(), 0);
+            assert_eq!(record.warc_id(), "<urn:test:zero-content-length>");
+            assert_eq!(record.body(), b"");
+        }
+
+        // Test the second record with non-zero Content-Length
+        {
+            let record = iter.next().unwrap().unwrap();
+            assert_eq!(record.warc_version(), "1.0");
+            assert_eq!(record.content_length(), 7);
+            assert_eq!(record.warc_id(), "<urn:test:nonzero-content-length>");
+            assert_eq!(record.body(), b"1234567");
+        }
+    }
 }