Merge pull request #1947 from Mouhand-Kaddo:fix/xls-dialog-sheets

crates/xlsx/src/tests/xls_tests.rs

@@ -454,6 +454,20 @@ fn hostile_xls_input_never_panics_or_hangs() {
     }
 }
 
+#[test]
+fn dialog_sheets_are_skipped_not_read_as_worksheets() {
+    let boundsheet = |pos: u32, name: &str| rec(0x0085, &cat(&[&pos.to_le_bytes(), &[0, 0, name.len() as u8, 0], name.as_bytes()]));
+    let globals = |positions: [u32; 2]| cat(&[&bof(0x0005), &boundsheet(positions[0], "Dialog1"), &boundsheet(positions[1], "Sheet1"), &eof()]);
+    let dialog = cat(&[&bof(0x0010), &rec(0x0081, &[0x10, 0x00]), &rec(0x0203, &cat(&[&cell(0, 0, 0), &1.0f64.to_le_bytes()])), &eof()]);
+    let worksheet = cat(&[&bof(0x0010), &rec(0x0081, &[0x01, 0x04]), &rec(0x0203, &cat(&[&cell(0, 0, 0), &7.0f64.to_le_bytes()])), &eof()]);
+    let first = globals([0; 2]).len() as u32;
+    let stream = cat(&[&globals([first, first + dialog.len() as u32]), &dialog, &worksheet]);
+    let (wb, report) = read_xls(&compound("Workbook", &stream)).unwrap();
+    assert_eq!(wb.sheets.iter().map(|s| s.name.as_str()).collect::<Vec<_>>(), ["Sheet1"]);
+    assert_eq!(v(&wb, 0, "A1"), Value::Number(7.0));
+    assert!(report.warnings.iter().any(|w| w.contains("Dialog sheets")), "{:?}", report.warnings);
+}
+
 #[test]
 fn sheets_share_one_record_budget() {
     // Many BoundSheet records point into one long substream (at successive nested BOFs), so each

crates/xlsx/src/xls/mod.rs

@@ -40,6 +40,9 @@ const MAX_RECORDS: usize = 40_000_000;
 const BOF: u16 = 0x0809;
 const EOF: u16 = 0x000A;
 const BIFF8: u16 = 0x0600;
+/// WsBool (MS-XLS 2.4.351): its first byte's `fDialog` bit marks a dialog sheet, whose BOF says worksheet.
+const WSBOOL: u16 = 0x0081;
+const WSBOOL_DIALOG: u8 = 0x10;
 
 pub(crate) fn invalid(msg: impl Into<String>) -> IoError {
     IoError::Format(format!("XLS: {}", msg.into()))
@@ -524,6 +527,7 @@ fn worksheet(
                 continue;
             }
             _ if depth > 1 => continue,
+            WSBOOL if rec.parts.first().and_then(|p| p.first()).is_some_and(|b| b & WSBOOL_DIALOG != 0) => return Ok(None),
             _ => {}
         }
         sheet_record(&rec, &mut st, budget, report)?;

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-14 · **Change:** trivial (formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; previously trivial: XLSX chart sheets are kept on save (#727)) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-19 · **Change:** minor (.xls dialog sheets are skipped instead of read as worksheets) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Every format Excel opens or saves, with GridCraft's read and write support, fidelity and tests.
 Part of [target-app-parity.md](target-app-parity.md). **File formats: ~50% ready, 80–120 h**
@@ -85,6 +85,7 @@ refresh. Counted under features (Get & Transform, ~10% ready), not here.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-19 | minor | .xls import skips dialog sheets (WsBool `fDialog`), which share the worksheet BOF type and were read as empty worksheets |
 | 2026-10-14 | trivial | Formula parser: text longer than Excel's 8,192 characters, and postfix chains (`1%%%…`, `f(1)(1)…`) past the 256-level nesting limit, are parse errors (the cell keeps its formula text and cached value) instead of trees deep enough to overflow the stack when a hostile file is opened, saved or dropped |
 | 2026-10-12 | trivial | XLSX chart sheets are kept on save (#727) |
 | 2026-10-12 | trivial | CSV and TSV export is capped at 512 MiB and refuses a larger used range with an error (#528) |