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LibJS: Handle empty UTF-16 strings in Rust FFI

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Treat zero length UTF-16 slices from Rust as empty views at the FFI
boundary instead of assuming a non null backing pointer.

Add a regression test which crashed before these changes. Fixes
a crash loading github.com/ladybirdbrowser/ladybird.
This commit is contained in:
Shannon Booth 2026-03-31 18:27:42 +02:00 committed by Andreas Kling
parent 7b0121e206
commit adabc5cedb
2 changed files with 30 additions and 12 deletions
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31
Libraries/LibJS/RustIntegration.cpp
View file

@ -35,23 +35,30 @@ namespace JS::RustIntegration {
// --- Shared helpers ---
static Utf16View utf16_view_from_bytes(uint16_t const* data, size_t len)
{
if (len == 0)
return {};
return Utf16View { reinterpret_cast<char16_t const*>(data), len };
}
static Utf16FlyString utf16_fly_from(uint16_t const* data, size_t len)
{
return Utf16FlyString::from_utf16(Utf16View { reinterpret_cast<char16_t const*>(data), len });
return Utf16FlyString::from_utf16(utf16_view_from_bytes(data, len));
}
static Utf16FlyString utf16_fly_from_raw(uint16_t const* data, size_t len)
{
if (len == 0)
return {};
return Utf16FlyString::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(data), len));
return Utf16FlyString::from_utf16(utf16_view_from_bytes(data, len));
}
static Utf16String utf16_from_raw(uint16_t const* data, size_t len)
{
if (len == 0)
return {};
return Utf16String::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(data), len));
return Utf16String::from_utf16(utf16_view_from_bytes(data, len));
}
// --- Error collection callbacks ---
@ -639,7 +646,7 @@ struct RustCompiledRegex {
static Utf16View view_from_ffi(FFIUtf16Slice slice)
{
return Utf16View { reinterpret_cast<char16_t const*>(slice.data), slice.length };
return JS::RustIntegration::utf16_view_from_bytes(slice.data, slice.length);
}
static Utf16String utf16_from_ffi(FFIUtf16Slice slice)
@ -917,7 +924,7 @@ extern "C" void rust_sfd_set_class_field_initializer_name(
bool is_private)
{
auto& shared = *static_cast<JS::SharedFunctionInstanceData*>(sfd_ptr);
auto utf16_name = Utf16FlyString::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(name), name_len));
auto utf16_name = Utf16FlyString::from_utf16(JS::RustIntegration::utf16_view_from_bytes(name, name_len));
if (is_private) {
shared.m_class_field_initializer_name = JS::PrivateName(0, utf16_name);
} else {
@ -944,7 +951,7 @@ extern "C" void* rust_create_class_blueprint(
blueprint->has_name = has_name;
if (name_len > 0)
blueprint->name = Utf16FlyString::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(name), name_len));
blueprint->name = Utf16FlyString::from_utf16(JS::RustIntegration::utf16_view_from_bytes(name, name_len));
// Store source text as a view into the SourceCode buffer.
if (source_text_len > 0) {
@ -960,7 +967,7 @@ extern "C" void* rust_create_class_blueprint(
desc.is_static = elem.is_static;
desc.is_private = elem.is_private;
if (elem.private_identifier_len > 0)
desc.private_identifier = Utf16FlyString::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(elem.private_identifier), elem.private_identifier_len));
desc.private_identifier = Utf16FlyString::from_utf16(JS::RustIntegration::utf16_view_from_bytes(elem.private_identifier, elem.private_identifier_len));
if (elem.shared_function_data_index.has_value)
desc.shared_function_data_index = elem.shared_function_data_index.value;
desc.has_initializer = elem.has_initializer;
@ -981,7 +988,7 @@ extern "C" void* rust_create_class_blueprint(
break;
case LiteralValueKind::String: {
auto& vm = *static_cast<JS::VM*>(vm_ptr);
auto str_view = Utf16View(reinterpret_cast<char16_t const*>(elem.literal_value_string), elem.literal_value_string_len);
auto str_view = JS::RustIntegration::utf16_view_from_bytes(elem.literal_value_string, elem.literal_value_string_len);
desc.literal_value = JS::Value(JS::PrimitiveString::create(vm, str_view));
break;
}
@ -998,7 +1005,7 @@ extern "C" void module_sfd_set_name(
size_t name_len)
{
auto& shared = *static_cast<JS::SharedFunctionInstanceData*>(sfd_ptr);
shared.m_name = Utf16FlyString::from_utf16(Utf16View(reinterpret_cast<char16_t const*>(name), name_len));
shared.m_name = Utf16FlyString::from_utf16(JS::RustIntegration::utf16_view_from_bytes(name, name_len));
}
extern "C" void* rust_compile_regex(
@ -1007,8 +1014,8 @@ extern "C" void* rust_compile_regex(
char const** error_out)
{
*error_out = nullptr;
auto pattern = Utf16View { reinterpret_cast<char16_t const*>(pattern_data), pattern_len };
auto flags_view = Utf16View { reinterpret_cast<char16_t const*>(flags_data), flags_len };
auto pattern = JS::RustIntegration::utf16_view_from_bytes(pattern_data, pattern_len);
auto flags_view = JS::RustIntegration::utf16_view_from_bytes(flags_data, flags_len);
// Extract unicode/unicode_sets from flags for parse_regex_pattern.
bool is_unicode = false;
@ -1133,7 +1140,7 @@ extern "C" uint64_t get_abstract_operation_function(void* vm_ptr, uint16_t const
{
auto& vm = *static_cast<JS::VM*>(vm_ptr);
auto& intrinsics = vm.current_realm()->intrinsics();
auto name_view = Utf16View(reinterpret_cast<char16_t const*>(name), name_len);
auto name_view = JS::RustIntegration::utf16_view_from_bytes(name, name_len);
auto name_str = MUST(name_view.to_utf8());
#define __JS_ENUMERATE(snake_name, functionName, length) \

11
Tests/LibJS/Runtime/classes/class-expressions.js
View file

@ -66,3 +66,14 @@ test("class expression name", () => {
let B = class C {};
expect(B.name).toBe("C");
});
test("empty string literal field initializers", () => {
const A = class {
x = "";
static y = "";
};
const a = new A();
expect(a.x).toBe("");
expect(A.y).toBe("");
});