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AK: Explicitly check for null data in Utf8View

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The underlying CPU-specific instructions for operating on UTF-8 strings
behave differently for null inputs. Add an explicit check for this state
for consistency.
This commit is contained in:
Timothy Flynn 2024-07-21 07:48:27 -04:00 • committed by Andreas Kling
parent ac6126e263
commit 144452d638
Notes: github-actions[bot] 2024-07-21 17:58:05 +00:00
2 changed files with 22 additions and 0 deletions
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10
AK/Utf8View.cpp
View file

@ -76,6 +76,10 @@ Utf8View Utf8View::unicode_substring_view(size_t code_point_offset, size_t code_
size_t Utf8View::calculate_length() const size_t Utf8View::calculate_length() const
{ {
// FIXME: The CPU-specific implementations behave differently on null inputs. We treat null views as an empty string.
if (is_empty())
return 0;
// FIXME: simdutf's code point length method assumes valid UTF-8, whereas Utf8View uses U+FFFD as a replacement // FIXME: simdutf's code point length method assumes valid UTF-8, whereas Utf8View uses U+FFFD as a replacement
// for invalid code points. If we change Utf8View to only accept valid encodings as an invariant, we can // for invalid code points. If we change Utf8View to only accept valid encodings as an invariant, we can
// remove this branch. // remove this branch.
@ -155,6 +159,12 @@ Utf8View Utf8View::trim(Utf8View const& characters, TrimMode mode) const
bool Utf8View::validate(size_t& valid_bytes, AllowSurrogates allow_surrogates) const bool Utf8View::validate(size_t& valid_bytes, AllowSurrogates allow_surrogates) const
{ {
// FIXME: The CPU-specific implementations behave differently on null inputs. We treat null views as an empty string.
if (is_empty()) {
valid_bytes = 0;
return true;
}
auto result = simdutf::validate_utf8_with_errors(m_string.characters_without_null_termination(), m_string.length()); auto result = simdutf::validate_utf8_with_errors(m_string.characters_without_null_termination(), m_string.length());
valid_bytes = result.count; valid_bytes = result.count;

12
Tests/AK/TestUtf8.cpp
View file

@ -48,6 +48,18 @@ TEST_CASE(decode_utf8)
EXPECT_EQ(i, expected_size); EXPECT_EQ(i, expected_size);
} }
TEST_CASE(null_view)
{
Utf8View view;
EXPECT(view.validate(Utf8View::AllowSurrogates::No));
EXPECT(view.validate(Utf8View::AllowSurrogates::Yes));
EXPECT_EQ(view.byte_length(), 0zu);
EXPECT_EQ(view.length(), 0zu);
for ([[maybe_unused]] auto it : view)
FAIL("Iterating a null UTF-8 string should not produce any values");
}
TEST_CASE(validate_invalid_ut8) TEST_CASE(validate_invalid_ut8)
{ {
size_t valid_bytes; size_t valid_bytes;