functions: one work budget across every call of a lifted function

A function lifted over a computed array runs once per element, and only the
six lookups counted their repeated work against LIFTED_SCAN_BUDGET. Criteria
aggregates rescanned their ranges per criterion, CUMIPMT/CUMPRINC stepped
through up to 1e7 periods per element, and array-producing functions such as
MUNIT built a whole result per element before keeping its first cell.

The budget now covers all of it: COUNTIF/SUMIF/AVERAGEIF(S)/MAXIFS/MINIFS
charge their range cells per call, the period loops of every element are
added up before any runs, and array results charge their cells as they are
built. Past the budget the call is #NUM!, as lifted lookups already are.

crates/engine/src/cmd/print/tests.rs

@@ -695,79 +695,6 @@ fn bands_unit() {
     assert!(w.len() > 2);
 }
 
-/// The wrapper `wrap_lines` replaced, re-measuring strings, as the reference for its lines.
-fn wrap_lines_remeasuring(text: &str, font: Font, size: f32, width: f32) -> Vec<String> {
-    let mut out = Vec::new();
-    for para in text.split('\n') {
-        let mut line = String::new();
-        for word in para.split(' ') {
-            let cand = if line.is_empty() { word.to_string() } else { format!("{line} {word}") };
-            if line.is_empty() || gridcraft_pdf::text_width(font, size, &cand) <= width {
-                line = cand;
-            } else {
-                out.push(std::mem::take(&mut line));
-                line = word.to_string();
-            }
-            while gridcraft_pdf::text_width(font, size, &line) > width && line.chars().count() > 1 {
-                let chars: Vec<char> = line.chars().collect();
-                let (mut lo, mut hi) = (1usize, chars.len());
-                while lo < hi {
-                    let mid = lo + (hi - lo).div_ceil(2);
-                    let cut: String = chars[..mid].iter().collect();
-                    if gridcraft_pdf::text_width(font, size, &cut) <= width {
-                        lo = mid;
-                    } else {
-                        hi = mid - 1;
-                    }
-                }
-                if lo == chars.len() {
-                    break;
-                }
-                out.push(chars[..lo].iter().collect());
-                line = chars[lo..].iter().collect();
-            }
-            if out.len() > 2000 {
-                return out;
-            }
-        }
-        out.push(line);
-    }
-    out
-}
-
-#[test]
-fn wrap_lines_matches_the_remeasuring_wrapper() {
-    let texts = [
-        "the quick brown fox jumps",
-        "Supercalifragilistic",
-        "a  b   c\n\nverylongwordthatneedsbreaking short\nend ",
-        "Wide WWWWWWWWWW words, iiiiiiii narrow ones; mixed MMMMiiiiMMMM",
-        "€ ü ß — unicode Ünïcödé text",
-        "",
-        " ",
-    ];
-    for text in texts {
-        for font in [Font::Helvetica, Font::HelveticaBold, Font::Courier] {
-            for (size, width) in [(10.0, 50.0), (10.0, 20.0), (11.0, 1.0), (8.0, 300.0), (12.0, 0.0)] {
-                assert_eq!(wrap_lines(text, font, size, width), wrap_lines_remeasuring(text, font, size, width), "{text:?} {font:?} {size} {width}");
-            }
-        }
-    }
-}
-
-#[test]
-fn wrapping_a_long_word_in_a_narrow_box_stops_at_the_line_limit() {
-    // One character per line: the old wrapper re-measured and copied the rest of the word for
-    // each of the 100,000 lines before checking the limit.
-    let word = "w".repeat(100_000);
-    let lines = wrap_lines(&word, Font::Helvetica, 10.0, 1.0);
-    assert!(lines.len() <= 2002, "{}", lines.len());
-    assert!(lines.iter().all(|l| l == "w"));
-    // A long paragraph in a very wide box is one line.
-    let para = vec!["word"; 50_000].join(" ");
-    assert_eq!(wrap_lines(&para, Font::Helvetica, 10.0, 1.0e9), vec![para.clone()]);
-}
-
 #[test]
 fn center_across_spans_following_empty_center_across_cells() {
     let mut styles = StyleTable::default();

crates/engine/src/cmd/print/text.rs

@@ -3,57 +3,42 @@ use super::{CellRef, Color, Font, HAlign, MAX_COLS, Page, Point, RangeRef, Sheet
 
 const PAD_PX: f32 = 2.0;
 
-/// Most lines [`wrap_lines`] returns (it may return one more, the rest of a paragraph).
-const MAX_WRAP_LINES: usize = 2000;
-
 /// Word-wraps `text` to `width` points.
-///
-/// Widths are kept as running sums of glyph widths (the sum `text_width` makes), so each
-/// character is measured once: re-measuring the line for every word, or the rest of an
-/// over-long word for every piece cut from it, made a long paragraph or word quadratic.
 pub(super) fn wrap_lines(text: &str, font: Font, size: f32, width: f32) -> Vec<String> {
-    let units_of = |s: &str| -> u64 { s.chars().map(|c| u64::from(font.char_width(c))).sum() };
-    let fits = |units: u64| units as f32 * size / 1000.0 <= width;
-    let space = units_of(" ");
     let mut out = Vec::new();
     for para in text.split('\n') {
         let mut line = String::new();
-        let mut line_units: u64 = 0;
         for word in para.split(' ') {
-            let word_units = units_of(word);
-            if line.is_empty() {
-                line.push_str(word);
-                line_units = word_units;
-            } else if fits(line_units + space + word_units) {
-                line.push(' ');
-                line.push_str(word);
-                line_units += space + word_units;
+            let cand = if line.is_empty() { word.to_string() } else { format!("{line} {word}") };
+            if line.is_empty() || gridcraft_pdf::text_width(font, size, &cand) <= width {
+                line = cand;
             } else {
                 out.push(std::mem::take(&mut line));
-                line.push_str(word);
-                line_units = word_units;
+                line = word.to_string();
             }
-            // Break a single over-long word by characters: each piece is the longest that fits
-            // (at least one character).
-            if !fits(line_units) && line.chars().nth(1).is_some() {
-                let mut piece = String::new();
-                let mut units: u64 = 0;
-                for c in line.chars() {
-                    let w = u64::from(font.char_width(c));
-                    if !piece.is_empty() && !fits(units + w) {
-                        out.push(std::mem::take(&mut piece));
-                        units = 0;
-                        if out.len() > MAX_WRAP_LINES {
-                            return out;
-                        }
+            // Break a single over-long word by characters. The cut that fits is found by binary
+            // search (each try measures one candidate prefix), so an over-long word costs
+            // O(n log n) measurements instead of re-measuring the whole cut per character for
+            // every emitted line (`a` × 100k pasted text would be cubic worst case).
+            while gridcraft_pdf::text_width(font, size, &line) > width && line.chars().count() > 1 {
+                let chars: Vec<char> = line.chars().collect();
+                let (mut lo, mut hi) = (1usize, chars.len());
+                while lo < hi {
+                    let mid = lo + (hi - lo).div_ceil(2);
+                    let cut: String = chars[..mid].iter().collect();
+                    if gridcraft_pdf::text_width(font, size, &cut) <= width {
+                        lo = mid;
+                    } else {
+                        hi = mid - 1;
                     }
-                    piece.push(c);
-                    units += w;
                 }
-                line = piece;
-                line_units = units;
+                if lo == chars.len() {
+                    break;
+                }
+                out.push(chars[..lo].iter().collect());
+                line = chars[lo..].iter().collect();
             }
-            if out.len() > MAX_WRAP_LINES {
+            if out.len() > 2000 {
                 return out;
             }
         }

crates/functions/src/lift.rs

@@ -68,26 +68,70 @@ const SCANS: &[&str] = &["VLOOKUP", "HLOOKUP", "LOOKUP", "MATCH", "XLOOKUP", "XM
 /// `XMATCH(SEQUENCE(1048576), -SEQUENCE(1048576))` runs for hours and hangs opening the file.
 /// Past the budget the call is `#NUM!`, as MMULT is past 2e9 multiply-adds. 5e8 keeps the worst
 /// case to a few seconds and still admits 5,000 needles over a 100,000-row table.
+///
+/// The same budget covers all the work of a lifted call added up across its elements: criteria
+/// aggregates rescanning their ranges, period loops, and array results built per element.
 const LIFTED_SCAN_BUDGET: usize = 500_000_000;
 
-/// The length of the longest vector a lifted call of `spec` searches per needle: 0 unless `spec`
-/// is one of the [`SCANS`] lookups and a non-lifted argument is an array.
+/// Criteria aggregates: every call tests each cell of its ranges against its criteria, so a call
+/// lifted over `n` criteria does `n` x (range cells) work, like the [`SCANS`] lookups.
+const CRITERIA: &[&str] = &["COUNTIF", "COUNTIFS", "SUMIF", "SUMIFS", "AVERAGEIF", "AVERAGEIFS", "MAXIFS", "MINIFS"];
+
+/// Cumulative TVM functions that step through every period from `start_period` (argument 3) to
+/// `end_period` (argument 4) on each call.
+const PERIOD_LOOPS: &[&str] = &["CUMIPMT", "CUMPRINC"];
+
+/// The work every lifted call of `spec` repeats over its non-lifted arguments: the longest vector
+/// a [`SCANS`] lookup searches, or every cell a [`CRITERIA`] aggregate tests. 0 for other
+/// functions.
 fn scan_len(spec: &FnSpec, args: &[Arg]) -> usize {
-    if !SCANS.contains(&spec.name) {
+    let scans = SCANS.contains(&spec.name);
+    if !scans && !CRITERIA.contains(&spec.name) {
         return 0;
     }
-    args.iter()
-        .enumerate()
-        .filter(|(i, _)| !spec.is_scalar_arg(*i))
-        .filter_map(|(_, a)| match &a.value {
-            Value::Array(arr) => Some(arr.rows.max(arr.cols)),
-            _ => None,
-        })
-        .max()
-        .unwrap_or(0)
+    let lens = args.iter().enumerate().filter(|(i, _)| !spec.is_scalar_arg(*i)).filter_map(|(_, a)| match &a.value {
+        Value::Array(arr) => Some(if scans { arr.rows.max(arr.cols) } else { arr.data.len() }),
+        _ => None,
+    });
+    if scans { lens.max().unwrap_or(0) } else { lens.fold(0, usize::saturating_add) }
+}
+
+/// The work of one lifted call that depends on its own (lifted) scalar arguments: the number of
+/// periods a [`PERIOD_LOOPS`] function steps through. 0 for other functions.
+fn call_cost(spec: &FnSpec, cell_args: &[Arg]) -> usize {
+    if !PERIOD_LOOPS.contains(&spec.name) {
+        return 0;
+    }
+    let period = |i: usize| match cell_args.get(i).map(|a| &a.value) {
+        Some(Value::Number(n)) if n.is_finite() => Some(n.trunc()),
+        _ => None,
+    };
+    match (period(3), period(4)) {
+        // The function itself refuses spans past 1e7 periods; anything larger costs the cap.
+        (Some(start), Some(end)) if end >= start => ((end - start) + 1.0).min(1e8) as usize,
+        _ => 0,
+    }
 }
 
 pub(crate) fn call_lifted(spec: &FnSpec, args: &[Arg], ctx: &mut dyn Ctx) -> Value {
+    call_lifted_within(spec, args, ctx, LIFTED_SCAN_BUDGET)
+}
+
+/// Sets the lifted arguments of `cell_args` to their elements at (`r`, `c`).
+fn element_args(spec: &FnSpec, args: &[Arg], r: usize, c: usize, cell_args: &mut [Arg]) {
+    for (i, a) in args.iter().enumerate() {
+        if spec.is_scalar_arg(i)
+            && let Value::Array(arr) = &a.value
+            && let Some(slot) = cell_args.get_mut(i)
+        {
+            let v = arr.get_broadcast(r, c);
+            slot.value = if let Value::Array(inner) = &v { inner.data.first().cloned().unwrap_or(Value::Empty) } else { v };
+        }
+    }
+}
+
+/// [`call_lifted`] with every call's work added up against `budget` (see [`LIFTED_SCAN_BUDGET`]).
+fn call_lifted_within(spec: &FnSpec, args: &[Arg], ctx: &mut dyn Ctx, budget: usize) -> Value {
     let rejected = if spec.value_args.is_empty() { None } else { reject_multi_cell_refs(spec, args) };
     let args = rejected.as_deref().unwrap_or(args);
     let mut rows = 0usize;
@@ -106,25 +150,42 @@ pub(crate) fn call_lifted(spec: &FnSpec, args: &[Arg], ctx: &mut dyn Ctx) -> Val
         return (spec.imp)(args, ctx);
     }
     let needles = rows.saturating_mul(cols);
-    if needles > MAX_CELLS || needles.saturating_mul(scan_len(spec, args)) > LIFTED_SCAN_BUDGET {
+    // Every call is charged its repeated scan (at least 1), its own period loop, and the cells of
+    // an array result (built in full, though only its first cell is kept), so lifting a scalar
+    // argument can't multiply what one call may do into hours of work:
+    // `COUNTIF(big_range, SEQUENCE(1e4))`, `CUMIPMT(0.1, 1e7, 1, 1, SEQUENCE(1e4,,1e7,0), 0)`,
+    // `MUNIT(SEQUENCE(1e4,,3000,0))`.
+    let per_call = scan_len(spec, args).max(1);
+    let mut cell_args: Vec<Arg> = args.to_vec();
+    let mut spent = needles.saturating_mul(per_call);
+    if needles > MAX_CELLS || spent > budget {
         return Value::Error(CellError::Num);
     }
-    let mut cell_args: Vec<Arg> = args.to_vec();
+    // Period loops are known before any call runs, so a call over budget does none of them.
+    if PERIOD_LOOPS.contains(&spec.name) {
+        for r in 0..rows {
+            for c in 0..cols {
+                element_args(spec, args, r, c, &mut cell_args);
+                spent = spent.saturating_add(call_cost(spec, &cell_args));
+                if spent > budget {
+                    return Value::Error(CellError::Num);
+                }
+            }
+        }
+    }
     let mut data = Vec::with_capacity(rows * cols);
     for r in 0..rows {
         for c in 0..cols {
-            for (i, a) in args.iter().enumerate() {
-                if spec.is_scalar_arg(i)
-                    && let Value::Array(arr) = &a.value
-                    && let Some(slot) = cell_args.get_mut(i)
-                {
-                    let v = arr.get_broadcast(r, c);
-                    slot.value = if let Value::Array(inner) = &v { inner.data.first().cloned().unwrap_or(Value::Empty) } else { v };
-                }
-            }
+            element_args(spec, args, r, c, &mut cell_args);
             let out = (spec.imp)(&cell_args, ctx);
             data.push(match out {
-                Value::Array(a) => a.data.first().cloned().unwrap_or(Value::Empty),
+                Value::Array(a) => {
+                    spent = spent.saturating_add(a.data.len());
+                    if spent > budget {
+                        return Value::Error(CellError::Num);
+                    }
+                    a.data.first().cloned().unwrap_or(Value::Empty)
+                }
                 v => v,
             });
         }
@@ -209,6 +270,52 @@ mod tests {
         assert_eq!(rows_of(&out), vec![vec![nv(-1.0)]; 1000]);
     }
 
+    /// Security: lifting a criteria aggregate rescans its range for every criterion, so criteria
+    /// x range cells past the budget is `#NUM!` before any scan runs.
+    #[test]
+    fn lifted_criteria_aggregates_stop_past_their_work_budget() {
+        use gridcraft_core::Array;
+        let tall = |n: usize| av(Array::filled(n, 1, nv(-1.0)).into());
+        is_err(ev("COUNTIF", vec![tall(1_000_000), tall(501)]), CellError::Num);
+        is_err(ev("SUMIF", vec![tall(1_000_000), tall(501)]), CellError::Num);
+        is_err(ev("COUNTIFS", vec![tall(1_000_000), tall(501)]), CellError::Num);
+        // Two ranges of 250,000 cells each count together.
+        is_err(ev("SUMIFS", vec![tall(250_000), tall(250_000), tall(1001)]), CellError::Num);
+        let counts = ev("COUNTIF", vec![av(col(&[1.0, 2.0, 2.0])), av(col(&[2.0, 1.0, 5.0]))]);
+        assert_eq!(rows_of(&counts), vec![vec![nv(2.0)], vec![nv(1.0)], vec![nv(0.0)]]);
+        for name in super::CRITERIA.iter().chain(super::PERIOD_LOOPS) {
+            assert!(crate::lookup(name).is_some(), "{name} isn't registered");
+        }
+    }
+
+    /// Security: CUMIPMT and CUMPRINC loop over their periods once per lifted element; the
+    /// periods of all elements are added up first, so an over-budget call runs none of them.
+    #[test]
+    fn lifted_period_loops_stop_past_their_work_budget() {
+        use gridcraft_core::Array;
+        let ends = |len: usize, end: f64| av(Array::filled(len, 1, nv(end)).into());
+        let args = |len: usize, end: f64| vec![n(0.01), n(1e7), n(1000.0), n(1.0), ends(len, end), n(0.0)];
+        // 51 elements of 1e7 periods each is past 5e8.
+        is_err(ev("CUMIPMT", args(51, 1e7)), CellError::Num);
+        is_err(ev("CUMPRINC", args(51, 1e7)), CellError::Num);
+        let out = ev("CUMIPMT", args(2, 12.0));
+        assert_eq!(rows_of(&out).len(), 2);
+        assert!(matches!(rows_of(&out).first().and_then(|r| r.first()), Some(Value::Number(x)) if *x < 0.0));
+    }
+
+    /// Security: an array-producing function lifted over a computed array builds each element's
+    /// whole result before keeping one cell; their cells count against the budget.
+    #[test]
+    fn lifted_array_results_count_against_the_budget() {
+        use gridcraft_core::Array;
+        let spec = crate::lookup("MUNIT").unwrap_or_else(|| panic!("MUNIT isn't registered"));
+        let dims = |n: usize| [av(Array::filled(n, 1, nv(10.0)).into())];
+        // Ten 10x10 identity matrices are 1,000 cells.
+        let out = super::call_lifted_within(spec, &dims(10), &mut TestCtx::default(), 1_010);
+        assert_eq!(rows_of(&out), vec![vec![nv(1.0)]; 10]);
+        is_err(super::call_lifted_within(spec, &dims(11), &mut TestCtx::default(), 1_010), CellError::Num);
+    }
+
     #[test]
     fn value_params_reject_multi_cell_references() {
         let s = FnSpec { value_args: &[true, false], ..spec() };