[lldb] Fix data race in statusline format handling (llvm#142489)

JDevlieghere · rorth · commit f9a5b1fdaf6c · 2025-06-11T14:12:09.000+02:00
This fixes a data race between the main thread and the default event
handler thread. The statusline format option value was protected by a
mutex, but it was returned as a pointer, allowing one thread to access
it while another was modifying it.

Avoid the data race by returning format values by value instead of by
pointer.
diff --git a/lldb/include/lldb/Core/Debugger.h b/lldb/include/lldb/Core/Debugger.h
@@ -243,17 +243,17 @@ class Debugger : public std::enable_shared_from_this<Debugger>,
 
   bool GetAutoConfirm() const;
 
-  const FormatEntity::Entry *GetDisassemblyFormat() const;
+  FormatEntity::Entry GetDisassemblyFormat() const;
 
-  const FormatEntity::Entry *GetFrameFormat() const;
+  FormatEntity::Entry GetFrameFormat() const;
 
-  const FormatEntity::Entry *GetFrameFormatUnique() const;
+  FormatEntity::Entry GetFrameFormatUnique() const;
 
   uint64_t GetStopDisassemblyMaxSize() const;
 
-  const FormatEntity::Entry *GetThreadFormat() const;
+  FormatEntity::Entry GetThreadFormat() const;
 
-  const FormatEntity::Entry *GetThreadStopFormat() const;
+  FormatEntity::Entry GetThreadStopFormat() const;
 
   lldb::ScriptLanguage GetScriptLanguage() const;
 
@@ -297,7 +297,7 @@ class Debugger : public std::enable_shared_from_this<Debugger>,
 
   bool GetShowStatusline() const;
 
-  const FormatEntity::Entry *GetStatuslineFormat() const;
+  FormatEntity::Entry GetStatuslineFormat() const;
   bool SetStatuslineFormat(const FormatEntity::Entry &format);
 
   llvm::StringRef GetSeparator() const;
diff --git a/lldb/include/lldb/Core/FormatEntity.h b/lldb/include/lldb/Core/FormatEntity.h
@@ -205,6 +205,8 @@ struct Entry {
     return true;
   }
 
+  operator bool() const { return type != Type::Invalid; }
+
   std::vector<Entry> &GetChildren();
 
   std::string string;
@@ -217,7 +219,7 @@ struct Entry {
   size_t level = 0;
   /// @}
 
-  Type type;
+  Type type = Type::Invalid;
   lldb::Format fmt = lldb::eFormatDefault;
   lldb::addr_t number = 0;
   bool deref = false;
diff --git a/lldb/include/lldb/Interpreter/OptionValue.h b/lldb/include/lldb/Interpreter/OptionValue.h
@@ -284,6 +284,8 @@ class OptionValue {
       return GetStringValue();
     if constexpr (std::is_same_v<T, ArchSpec>)
       return GetArchSpecValue();
+    if constexpr (std::is_same_v<T, FormatEntity::Entry>)
+      return GetFormatEntityValue();
     if constexpr (std::is_enum_v<T>)
       if (std::optional<int64_t> value = GetEnumerationValue())
         return static_cast<T>(*value);
@@ -295,11 +297,9 @@ class OptionValue {
                 typename std::remove_pointer<T>::type>::type,
             std::enable_if_t<std::is_pointer_v<T>, bool> = true>
   T GetValueAs() const {
-    if constexpr (std::is_same_v<U, FormatEntity::Entry>)
-      return GetFormatEntity();
-    if constexpr (std::is_same_v<U, RegularExpression>)
-      return GetRegexValue();
-    return {};
+    static_assert(std::is_same_v<U, RegularExpression>,
+                  "only for RegularExpression");
+    return GetRegexValue();
   }
 
   bool SetValueAs(bool v) { return SetBooleanValue(v); }
@@ -382,7 +382,7 @@ class OptionValue {
   std::optional<UUID> GetUUIDValue() const;
   bool SetUUIDValue(const UUID &uuid);
 
-  const FormatEntity::Entry *GetFormatEntity() const;
+  FormatEntity::Entry GetFormatEntityValue() const;
   bool SetFormatEntityValue(const FormatEntity::Entry &entry);
 
   const RegularExpression *GetRegexValue() const;
diff --git a/lldb/include/lldb/Target/Language.h b/lldb/include/lldb/Target/Language.h
@@ -495,9 +495,7 @@ class Language : public PluginInterface {
   /// Python uses \b except. Defaults to \b catch.
   virtual llvm::StringRef GetCatchKeyword() const { return "catch"; }
 
-  virtual const FormatEntity::Entry *GetFunctionNameFormat() const {
-    return nullptr;
-  }
+  virtual FormatEntity::Entry GetFunctionNameFormat() const { return {}; }
 
 protected:
   // Classes that inherit from Language can see and modify these
diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
@@ -294,19 +294,19 @@ bool Debugger::GetAutoConfirm() const {
       idx, g_debugger_properties[idx].default_uint_value != 0);
 }
 
-const FormatEntity::Entry *Debugger::GetDisassemblyFormat() const {
+FormatEntity::Entry Debugger::GetDisassemblyFormat() const {
   constexpr uint32_t idx = ePropertyDisassemblyFormat;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
-const FormatEntity::Entry *Debugger::GetFrameFormat() const {
+FormatEntity::Entry Debugger::GetFrameFormat() const {
   constexpr uint32_t idx = ePropertyFrameFormat;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
-const FormatEntity::Entry *Debugger::GetFrameFormatUnique() const {
+FormatEntity::Entry Debugger::GetFrameFormatUnique() const {
   constexpr uint32_t idx = ePropertyFrameFormatUnique;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
 uint64_t Debugger::GetStopDisassemblyMaxSize() const {
@@ -350,14 +350,14 @@ void Debugger::SetPrompt(llvm::StringRef p) {
   GetCommandInterpreter().UpdatePrompt(new_prompt);
 }
 
-const FormatEntity::Entry *Debugger::GetThreadFormat() const {
+FormatEntity::Entry Debugger::GetThreadFormat() const {
   constexpr uint32_t idx = ePropertyThreadFormat;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
-const FormatEntity::Entry *Debugger::GetThreadStopFormat() const {
+FormatEntity::Entry Debugger::GetThreadStopFormat() const {
   constexpr uint32_t idx = ePropertyThreadStopFormat;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
 lldb::ScriptLanguage Debugger::GetScriptLanguage() const {
@@ -492,9 +492,9 @@ bool Debugger::GetShowStatusline() const {
       idx, g_debugger_properties[idx].default_uint_value != 0);
 }
 
-const FormatEntity::Entry *Debugger::GetStatuslineFormat() const {
+FormatEntity::Entry Debugger::GetStatuslineFormat() const {
   constexpr uint32_t idx = ePropertyStatuslineFormat;
-  return GetPropertyAtIndexAs<const FormatEntity::Entry *>(idx);
+  return GetPropertyAtIndexAs<FormatEntity::Entry>(idx, {});
 }
 
 bool Debugger::SetStatuslineFormat(const FormatEntity::Entry &format) {
@@ -1536,8 +1536,11 @@ bool Debugger::FormatDisassemblerAddress(const FormatEntity::Entry *format,
   FormatEntity::Entry format_entry;
 
   if (format == nullptr) {
-    if (exe_ctx != nullptr && exe_ctx->HasTargetScope())
-      format = exe_ctx->GetTargetRef().GetDebugger().GetDisassemblyFormat();
+    if (exe_ctx != nullptr && exe_ctx->HasTargetScope()) {
+      format_entry =
+          exe_ctx->GetTargetRef().GetDebugger().GetDisassemblyFormat();
+      format = &format_entry;
+    }
     if (format == nullptr) {
       FormatEntity::Parse("${addr}: ", format_entry);
       format = &format_entry;
diff --git a/lldb/source/Core/Disassembler.cpp b/lldb/source/Core/Disassembler.cpp
@@ -310,8 +310,8 @@ void Disassembler::PrintInstructions(Debugger &debugger, const ArchSpec &arch,
   const FormatEntity::Entry *disassembly_format = nullptr;
   FormatEntity::Entry format;
   if (exe_ctx.HasTargetScope()) {
-    disassembly_format =
-        exe_ctx.GetTargetRef().GetDebugger().GetDisassemblyFormat();
+    format = exe_ctx.GetTargetRef().GetDebugger().GetDisassemblyFormat();
+    disassembly_format = &format;
   } else {
     FormatEntity::Parse("${addr}: ", format);
     disassembly_format = &format;
@@ -1037,8 +1037,8 @@ void InstructionList::Dump(Stream *s, bool show_address, bool show_bytes,
   const FormatEntity::Entry *disassembly_format = nullptr;
   FormatEntity::Entry format;
   if (exe_ctx && exe_ctx->HasTargetScope()) {
-    disassembly_format =
-        exe_ctx->GetTargetRef().GetDebugger().GetDisassemblyFormat();
+    format = exe_ctx->GetTargetRef().GetDebugger().GetDisassemblyFormat();
+    disassembly_format = &format;
   } else {
     FormatEntity::Parse("${addr}: ", format);
     disassembly_format = &format;
diff --git a/lldb/source/Core/FormatEntity.cpp b/lldb/source/Core/FormatEntity.cpp
@@ -1279,13 +1279,13 @@ static bool FormatFunctionNameForLanguage(Stream &s,
   if (!language_plugin)
     return false;
 
-  const auto *format = language_plugin->GetFunctionNameFormat();
+  FormatEntity::Entry format = language_plugin->GetFunctionNameFormat();
   if (!format)
     return false;
 
   StreamString name_stream;
   const bool success =
-      FormatEntity::Format(*format, name_stream, sc, exe_ctx, /*addr=*/nullptr,
+      FormatEntity::Format(format, name_stream, sc, exe_ctx, /*addr=*/nullptr,
                            /*valobj=*/nullptr, /*function_changed=*/false,
                            /*initial_function=*/false);
   if (success)
diff --git a/lldb/source/Core/Statusline.cpp b/lldb/source/Core/Statusline.cpp
@@ -144,9 +144,9 @@ void Statusline::Redraw(bool update) {
   }
 
   StreamString stream;
-  if (auto *format = m_debugger.GetStatuslineFormat())
-    FormatEntity::Format(*format, stream, &symbol_ctx, &exe_ctx, nullptr,
-                         nullptr, false, false);
+  FormatEntity::Entry format = m_debugger.GetStatuslineFormat();
+  FormatEntity::Format(format, stream, &symbol_ctx, &exe_ctx, nullptr, nullptr,
+                       false, false);
 
-  Draw(std::string(stream.GetString()));
+  Draw(stream.GetString().str());
 }
diff --git a/lldb/source/Interpreter/OptionValue.cpp b/lldb/source/Interpreter/OptionValue.cpp
@@ -380,11 +380,11 @@ bool OptionValue::SetLanguageValue(lldb::LanguageType new_language) {
   return false;
 }
 
-const FormatEntity::Entry *OptionValue::GetFormatEntity() const {
+FormatEntity::Entry OptionValue::GetFormatEntityValue() const {
   std::lock_guard<std::mutex> lock(m_mutex);
   if (const OptionValueFormatEntity *option_value = GetAsFormatEntity())
-    return &option_value->GetCurrentValue();
-  return nullptr;
+    return option_value->GetCurrentValue();
+  return {};
 }
 
 const RegularExpression *OptionValue::GetRegexValue() const {
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -2066,9 +2066,9 @@ class PluginProperties : public Properties {
     m_collection_sp->Initialize(g_language_cplusplus_properties);
   }
 
-  const FormatEntity::Entry *GetFunctionNameFormat() const {
-    return GetPropertyAtIndexAs<const FormatEntity::Entry *>(
-        ePropertyFunctionNameFormat);
+  FormatEntity::Entry GetFunctionNameFormat() const {
+    return GetPropertyAtIndexAs<FormatEntity::Entry>(
+        ePropertyFunctionNameFormat, {});
   }
 };
 } // namespace
@@ -2078,7 +2078,7 @@ static PluginProperties &GetGlobalPluginProperties() {
   return g_settings;
 }
 
-const FormatEntity::Entry *CPlusPlusLanguage::GetFunctionNameFormat() const {
+FormatEntity::Entry CPlusPlusLanguage::GetFunctionNameFormat() const {
   return GetGlobalPluginProperties().GetFunctionNameFormat();
 }
 
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
@@ -93,8 +93,8 @@ class CPlusPlusLanguage : public Language {
   static llvm::StringRef GetPluginNameStatic() { return "cplusplus"; }
 
   bool SymbolNameFitsToLanguage(Mangled mangled) const override;
-  
-  bool DemangledNameContainsPath(llvm::StringRef path, 
+
+  bool DemangledNameContainsPath(llvm::StringRef path,
                                  ConstString demangled) const override;
 
   ConstString
@@ -136,7 +136,7 @@ class CPlusPlusLanguage : public Language {
 
   llvm::StringRef GetInstanceVariableName() override { return "this"; }
 
-  const FormatEntity::Entry *GetFunctionNameFormat() const override;
+  FormatEntity::Entry GetFunctionNameFormat() const override;
 
   // PluginInterface protocol
   llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
diff --git a/lldb/source/Target/StackFrame.cpp b/lldb/source/Target/StackFrame.cpp
@@ -1937,12 +1937,15 @@ void StackFrame::DumpUsingSettingsFormat(Stream *strm, bool show_unique,
   ExecutionContext exe_ctx(shared_from_this());
 
   const FormatEntity::Entry *frame_format = nullptr;
+  FormatEntity::Entry format_entry;
   Target *target = exe_ctx.GetTargetPtr();
   if (target) {
     if (show_unique) {
-      frame_format = target->GetDebugger().GetFrameFormatUnique();
+      format_entry = target->GetDebugger().GetFrameFormatUnique();
+      frame_format = &format_entry;
     } else {
-      frame_format = target->GetDebugger().GetFrameFormat();
+      format_entry = target->GetDebugger().GetFrameFormat();
+      frame_format = &format_entry;
     }
   }
   if (!DumpUsingFormat(*strm, frame_format, frame_marker)) {
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
@@ -1668,10 +1668,14 @@ void Thread::DumpUsingSettingsFormat(Stream &strm, uint32_t frame_idx,
   ExecutionContext exe_ctx(shared_from_this());
 
   const FormatEntity::Entry *thread_format;
-  if (stop_format)
-    thread_format = exe_ctx.GetTargetRef().GetDebugger().GetThreadStopFormat();
-  else
-    thread_format = exe_ctx.GetTargetRef().GetDebugger().GetThreadFormat();
+  FormatEntity::Entry format_entry;
+  if (stop_format) {
+    format_entry = exe_ctx.GetTargetRef().GetDebugger().GetThreadStopFormat();
+    thread_format = &format_entry;
+  } else {
+    format_entry = exe_ctx.GetTargetRef().GetDebugger().GetThreadFormat();
+    thread_format = &format_entry;
+  }
 
   assert(thread_format);
 
diff --git a/lldb/source/Target/ThreadPlanTracer.cpp b/lldb/source/Target/ThreadPlanTracer.cpp
@@ -174,11 +174,11 @@ void ThreadPlanAssemblyTracer::Log() {
         const bool show_control_flow_kind = true;
         Instruction *instruction =
             instruction_list.GetInstructionAtIndex(0).get();
-        const FormatEntity::Entry *disassemble_format =
+        FormatEntity::Entry disassemble_format =
             m_process.GetTarget().GetDebugger().GetDisassemblyFormat();
         instruction->Dump(stream_sp.get(), max_opcode_byte_size, show_address,
                           show_bytes, show_control_flow_kind, nullptr, nullptr,
-                          nullptr, disassemble_format, 0);
+                          nullptr, &disassemble_format, 0);
       }
     }
   }
diff --git a/lldb/unittests/Core/DebuggerTest.cpp b/lldb/unittests/Core/DebuggerTest.cpp
@@ -46,7 +46,7 @@ TEST_F(DebuggerTest, TestSettings) {
 
   FormatEntity::Entry format("foo");
   EXPECT_TRUE(debugger_sp->SetStatuslineFormat(format));
-  EXPECT_EQ(debugger_sp->GetStatuslineFormat()->string, "foo");
+  EXPECT_EQ(debugger_sp->GetStatuslineFormat().string, "foo");
 
   Debugger::Destroy(debugger_sp);
 }

Original file line number	Diff line number	Diff line change
`@@ -144,9 +144,9 @@ void Statusline::Redraw(bool update) {`
`144`	`144`	`}`
`145`	`145`
`146`	`146`	`StreamString stream;`
`147`		`- if (auto *format = m_debugger.GetStatuslineFormat())`
`148`		`- FormatEntity::Format(*format, stream, &symbol_ctx, &exe_ctx, nullptr,`
`149`		`- nullptr, false, false);`
	`147`	`+ FormatEntity::Entry format = m_debugger.GetStatuslineFormat();`
	`148`	`+ FormatEntity::Format(format, stream, &symbol_ctx, &exe_ctx, nullptr, nullptr,`
	`149`	`+ false, false);`
`150`	`150`
`151`		`- Draw(std::string(stream.GetString()));`
	`151`	`+ Draw(stream.GetString().str());`
`152`	`152`	`}`
Original file line number	Diff line number	Diff line change
`@@ -380,11 +380,11 @@ bool OptionValue::SetLanguageValue(lldb::LanguageType new_language) {`
`380`	`380`	`return false;`
`381`	`381`	`}`
`382`	`382`
`383`		`-const FormatEntity::Entry *OptionValue::GetFormatEntity() const {`
	`383`	`+FormatEntity::Entry OptionValue::GetFormatEntityValue() const {`
`384`	`384`	`std::lock_guard<std::mutex> lock(m_mutex);`
`385`	`385`	`if (const OptionValueFormatEntity *option_value = GetAsFormatEntity())`
`386`		`- return &option_value->GetCurrentValue();`
`387`		`- return nullptr;`
	`386`	`+ return option_value->GetCurrentValue();`
	`387`	`+ return {};`
`388`	`388`	`}`
`389`	`389`
`390`	`390`	`const RegularExpression *OptionValue::GetRegexValue() const {`
Original file line number	Diff line number	Diff line change
`@@ -2066,9 +2066,9 @@ class PluginProperties : public Properties {`
`2066`	`2066`	`m_collection_sp->Initialize(g_language_cplusplus_properties);`
`2067`	`2067`	`}`
`2068`	`2068`
`2069`		`- const FormatEntity::Entry *GetFunctionNameFormat() const {`
`2070`		`- return GetPropertyAtIndexAs<const FormatEntity::Entry *>(`
`2071`		`- ePropertyFunctionNameFormat);`
	`2069`	`+ FormatEntity::Entry GetFunctionNameFormat() const {`
	`2070`	`+ return GetPropertyAtIndexAs<FormatEntity::Entry>(`
	`2071`	`+ ePropertyFunctionNameFormat, {});`
`2072`	`2072`	`}`
`2073`	`2073`	`};`
`2074`	`2074`	`} // namespace`
`@@ -2078,7 +2078,7 @@ static PluginProperties &GetGlobalPluginProperties() {`
`2078`	`2078`	`return g_settings;`
`2079`	`2079`	`}`
`2080`	`2080`
`2081`		`-const FormatEntity::Entry *CPlusPlusLanguage::GetFunctionNameFormat() const {`
	`2081`	`+FormatEntity::Entry CPlusPlusLanguage::GetFunctionNameFormat() const {`
`2082`	`2082`	`return GetGlobalPluginProperties().GetFunctionNameFormat();`
`2083`	`2083`	`}`
`2084`	`2084`