Byte buffers holding XLUnicodeString prematurely truncated

src/xls.rs

@@ -500,7 +500,15 @@ impl<RS: Read + Seek> Xls<RS> {
                         });
                         formulas.push(Cell::new(fmla_pos, fmla));
                     }
-                    _ => (),
+                    // tests/high_byte_string.xls contains a record type that
+                    // cannot be found in the "By Number" 2.3.2 table
+                    0x00D6 => {
+                        let Ok(s) = parse_label(r.data, &encoding, biff) else {
+                            continue;
+                        };
+                        cells.push(s);
+                    }
+                    _ => {}
                 }
             }
             let range = Range::from_sparse(cells);
@@ -1035,8 +1043,8 @@ fn read_dbcs(
     Ok(s)
 }
 
-fn read_unicode_string_no_cch(encoding: &XlsEncoding, buf: &[u8], len: &usize, s: &mut String) {
-    encoding.decode_to(&buf[1..=*len], *len, s, Some(buf[0] & 0x1 != 0));
+fn read_unicode_string_no_cch(enc: &XlsEncoding, buf: &[u8], len: &usize, s: &mut String) -> usize {
+    enc.decode_to(&buf[1..], *len, s, Some(buf[0] & 0x1 != 0)).1
 }
 
 struct Record<'a> {
@@ -1311,9 +1319,9 @@ fn parse_formula(
                 stack.push(formula.len());
                 formula.push('\"');
                 let cch = rgce[0] as usize;
-                read_unicode_string_no_cch(encoding, &rgce[1..], &cch, &mut formula);
+                let l = read_unicode_string_no_cch(encoding, &rgce[1..], &cch, &mut formula);
                 formula.push('\"');
-                rgce = &rgce[2 + cch..];
+                rgce = &rgce[2 + l..];
             }
             0x18 => {
                 rgce = &rgce[5..];

tests/test.rs

@@ -2264,3 +2264,25 @@ fn test_xlsb_case_insensitive_part_name() {
 fn test_xlsx_backward_slash_part_name() {
     let _: Xlsx<_> = wb("issue_530.xlsx");
 }
+
+#[test]
+fn test_high_byte_strings() {
+    // file contains as well as record types that do not seem to be present in the spec
+    let mut xls: Xls<_> = wb("high_byte_string.xls");
+    for (_name, ws) in xls.worksheets() {
+        for (row, _col, cell) in ws.used_cells() {
+            if row == 3 {
+                assert_eq!(
+                    cell.as_string().unwrap(),
+                    "Inside FERC's Gas Market Report monthly bidweek price file.  "
+                );
+            }
+        }
+    }
+    // FIXME: Libreoffice recognizes a REPT("O", I44) formula
+    let formulas = xls.worksheet_formula("Sheet1").unwrap();
+    assert_eq!(
+        "Unrecognised formula for cell (43, 9): Unrecognized { typ: \"ptg\", val: 192 }",
+        formulas.get_value((43, 9)).unwrap()
+    );
+}