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LibGfx/OpenType: Allow zero-sized table entries

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Kind of reverts #21675, but #21744 made that better

4 of my 1000 test PDFs complained "Invalid table offset or length in
font" before.

For example, in 0000203.pdf, these tags had length 0: 'cvt ', 'fpgm',
'prep', 'name', 'OS/2'. (Generally it's tables that aren't needed
for rendering PDFs, and the PDF writer figured it's easier to zero
out these tables instead of omitting them altogether for some reason.)

Increases number of PDFs that render without diagnostics from
765 to 767.
This commit is contained in:
Nico Weber 2024-02-20 12:14:37 -05:00 • committed by Andreas Kling
parent cade76d240
commit 08381b20e0
1 changed files with 1 additions and 1 deletions
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2
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
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@ -210,7 +210,7 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
for (auto i = 0; i < table_directory.num_tables; i++) { for (auto i = 0; i < table_directory.num_tables; i++) {
auto& table_record = *TRY(stream.read_in_place<TableRecord const>()); auto& table_record = *TRY(stream.read_in_place<TableRecord const>());
if (table_record.length == 0 || Checked<u32>::addition_would_overflow(static_cast<u32>(table_record.offset), static_cast<u32>(table_record.length))) if (Checked<u32>::addition_would_overflow(static_cast<u32>(table_record.offset), static_cast<u32>(table_record.length)))
return Error::from_string_literal("Invalid table offset or length in font"); return Error::from_string_literal("Invalid table offset or length in font");
if (buffer.size() < table_record.offset + table_record.length) if (buffer.size() < table_record.offset + table_record.length)