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[LLDB][Value] Require type size when reading a scalar (#153386)

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When reading a value as a scalar, the type size is required. It's
returned as a `std::optional`. This optional isn't checked for scalar
values, where it is unconditionally accessed.

This came up in the
[Shell/Process/Windows/msstl_smoke.cpp](4e10b62442/lldb/test/Shell/Process/Windows/msstl_smoke.cpp)
test. There, LLDB breaks at the function entry, so all locals aren't
initialized yet. Most values will contain garbage. The [`std::list`
synthetic
provider](4e10b62442/lldb/source/Plugins/Language/CPlusPlus/GenericList.cpp (L517))
tries to read the value using `GetData`. However, in
[`ValueObject::GetData`](4e10b62442/lldb/source/ValueObject/ValueObject.cpp (L766)),
[`ValueObjectChild::UpdateValue`](88c993fbc5/lldb/source/ValueObject/ValueObjectChild.cpp (L102))
fails because the parent already failed to read its data, so `m_value`
won't have a compiler type, thus the size can't be read.
This commit is contained in:
nerix 2025-08-22 12:26:03 +02:00 committed by GitHub
parent 17dbb92612
commit d6fcaef281
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3 changed files with 43 additions and 0 deletions
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3
lldb/source/Core/Value.cpp
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@ -347,6 +347,9 @@ Status Value::GetValueAsData(ExecutionContext *exe_ctx, DataExtractor &data,
else else
data.SetAddressByteSize(sizeof(void *)); data.SetAddressByteSize(sizeof(void *));
if (!type_size)
return Status::FromErrorString("type does not have a size");
uint32_t result_byte_size = *type_size; uint32_t result_byte_size = *type_size;
if (m_value.GetData(data, result_byte_size)) if (m_value.GetData(data, result_byte_size))
return error; // Success; return error; // Success;

1
lldb/unittests/Core/CMakeLists.txt
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@ -15,6 +15,7 @@ add_lldb_unittest(LLDBCoreTests
SourceManagerTest.cpp SourceManagerTest.cpp
TelemetryTest.cpp TelemetryTest.cpp
UniqueCStringMapTest.cpp UniqueCStringMapTest.cpp
Value.cpp
LINK_COMPONENTS LINK_COMPONENTS
Support Support

39
lldb/unittests/Core/Value.cpp Normal file
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@ -0,0 +1,39 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Core/Value.h"
#include "Plugins/Platform/MacOSX/PlatformMacOSX.h"
#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
#include "TestingSupport/SubsystemRAII.h"
#include "TestingSupport/Symbol/ClangTestUtils.h"
#include "lldb/Utility/DataExtractor.h"
#include "gtest/gtest.h"
using namespace lldb_private;
using namespace lldb_private::clang_utils;
TEST(ValueTest, GetValueAsData) {
SubsystemRAII<FileSystem, HostInfo, PlatformMacOSX> subsystems;
auto holder = std::make_unique<clang_utils::TypeSystemClangHolder>("test");
auto *clang = holder->GetAST();
Value v(Scalar(42));
DataExtractor extractor;
// no compiler type
Status status = v.GetValueAsData(nullptr, extractor, nullptr);
ASSERT_TRUE(status.Fail());
// with compiler type
v.SetCompilerType(clang->GetBasicType(lldb::BasicType::eBasicTypeChar));
status = v.GetValueAsData(nullptr, extractor, nullptr);
ASSERT_TRUE(status.Success());
}