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Code Issues Projects Releases Packages Wiki Activity Actions 10

LibUnicode: Consistently reject out-of-bounds segmenter indices

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In the UTF-8 implementation, this prevents out-of-bounds access of the
underlying text data, as the ICU macro would essentially do something
akin to `text[text.length()]`.

The UTF-16 implementation already checks for out-of-bounds, but would
previously return 0. We now return an empty Optional in both impls. This
doesn't affect LibJS (the user of the UTF-16 impl), as it already does
bounds checking before invoking LibUnicode APIs.
This commit is contained in:
Timothy Flynn 2025-01-16 12:50:40 -05:00 • committed by Jelle Raaijmakers
commit e6b7c8cde2
Notes: github-actions[bot] 2025-01-16 22:23:49 +00:00
2 changed files with 49 additions and 10 deletions
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30
Libraries/LibUnicode/Segmenter.cpp
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@ -87,13 +87,15 @@ public:
virtual Optional<size_t> previous_boundary(size_t boundary, Inclusive inclusive) override
{
auto icu_boundary = align_boundary(boundary);
if (!icu_boundary.has_value())
return {};
if (inclusive == Inclusive::Yes) {
if (static_cast<bool>(m_segmenter->isBoundary(icu_boundary)))
return static_cast<size_t>(icu_boundary);
if (static_cast<bool>(m_segmenter->isBoundary(*icu_boundary)))
return static_cast<size_t>(*icu_boundary);
}
if (auto index = m_segmenter->preceding(icu_boundary); index != icu::BreakIterator::DONE)
if (auto index = m_segmenter->preceding(*icu_boundary); index != icu::BreakIterator::DONE)
return static_cast<size_t>(index);
return {};
@ -102,13 +104,15 @@ public:
virtual Optional<size_t> next_boundary(size_t boundary, Inclusive inclusive) override
{
auto icu_boundary = align_boundary(boundary);
if (!icu_boundary.has_value())
return {};
if (inclusive == Inclusive::Yes) {
if (static_cast<bool>(m_segmenter->isBoundary(icu_boundary)))
return static_cast<size_t>(icu_boundary);
if (static_cast<bool>(m_segmenter->isBoundary(*icu_boundary)))
return static_cast<size_t>(*icu_boundary);
}
if (auto index = m_segmenter->following(icu_boundary); index != icu::BreakIterator::DONE)
if (auto index = m_segmenter->following(*icu_boundary); index != icu::BreakIterator::DONE)
return static_cast<size_t>(index);
return {};
@ -173,19 +177,25 @@ public:
}
private:
i32 align_boundary(size_t boundary)
Optional<i32> align_boundary(size_t boundary)
{
auto icu_boundary = static_cast<i32>(boundary);
return m_segmented_text.visit(
[&](String const& text) {
[&](String const& text) -> Optional<i32> {
if (boundary >= text.byte_count())
return {};
U8_SET_CP_START(text.bytes().data(), 0, icu_boundary);
return icu_boundary;
},
[&](icu::UnicodeString const& text) {
[&](icu::UnicodeString const& text) -> Optional<i32> {
if (icu_boundary >= text.length())
return {};
return text.getChar32Start(icu_boundary);
},
[](Empty) -> i32 { VERIFY_NOT_REACHED(); });
[](Empty) -> Optional<i32> { VERIFY_NOT_REACHED(); });
}
void for_each_boundary(SegmentationCallback callback)