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LibWeb: Avoid division by zero when computing table measures

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For malformed tables which only have cells with span greater than 1, the
content sizes for row and column aren't initialized to non-zero values.
Avoid undefined behavior in such cases, which sometimes show up on
Wikipedia.
This commit is contained in:
Andi Gallo 2023-07-27 00:43:26 +00:00 • committed by Andreas Kling
parent 47595b9ef0
commit 3b75b9ef1c
3 changed files with 39 additions and 4 deletions
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12
Userland/Libraries/LibWeb/Layout/TableFormattingContext.cpp
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@ -495,8 +495,10 @@ void TableFormattingContext::compute_table_measures()
// the product of:
// - the ratio of the max-content size based on cells of span up to N-1 of the column to the baseline max-content size
// - the outer min-content size of the cell minus the baseline max-content size and baseline border spacing, or 0 if this is negative
cell_min_contribution += (rows_or_columns[rc_index].max_size / static_cast<double>(baseline_max_content_size))
* max(CSSPixels(0), cell_min_size<RowOrColumn>(cell) - baseline_max_content_size - baseline_border_spacing);
if (baseline_max_content_size != 0) {
cell_min_contribution += (rows_or_columns[rc_index].max_size / static_cast<double>(baseline_max_content_size))
* max(CSSPixels(0), cell_min_size<RowOrColumn>(cell) - baseline_max_content_size - baseline_border_spacing);
}
// The contribution of the cell is the sum of:
// the max-content size of the column based on cells of span up to N-1
@ -504,8 +506,10 @@ void TableFormattingContext::compute_table_measures()
// and the product of:
// - the ratio of the max-content size based on cells of span up to N-1 of the column to the baseline max-content size
// - the outer max-content size of the cell minus the baseline max-content size and the baseline border spacing, or 0 if this is negative
cell_max_contribution += (rows_or_columns[rc_index].max_size / static_cast<double>(baseline_max_content_size))
* max(CSSPixels(0), cell_max_size<RowOrColumn>(cell) - baseline_max_content_size - baseline_border_spacing);
if (baseline_max_content_size != 0) {
cell_max_contribution += (rows_or_columns[rc_index].max_size / static_cast<double>(baseline_max_content_size))
* max(CSSPixels(0), cell_max_size<RowOrColumn>(cell) - baseline_max_content_size - baseline_border_spacing);
}
cell_min_contributions_by_rc_index[rc_index].append(cell_min_contribution);
cell_max_contributions_by_rc_index[rc_index].append(cell_max_contribution);
}