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[LLDB/Lua] add support for one-liner breakpoint callback 

These callbacks are set using the following:
   breakpoint command add -s lua -o "print('hello world!')"

The user supplied script is executed as:
   function (frame, bp_loc, ...)
      <body>
   end

So the local variables 'frame', 'bp_loc' and vararg are all accessible.
Any global variables declared will persist in the Lua interpreter.
A user should never hold 'frame' and 'bp_loc' in a global variable as
these userdatas are context dependent.

Differential Revision: https://reviews.llvm.org/D91508
This commit is contained in:
Pedro Tammela 2020-11-15 19:39:16 +00:00
parent 8e504615e9
commit a0d7406ae8
9 changed files with 224 additions and 0 deletions
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15
lldb/bindings/lua/lua-swigsafecast.swig Normal file
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@ -0,0 +1,15 @@
template <typename SBClass>
void
PushSBClass (lua_State* L, SBClass* obj);
void
PushSBClass (lua_State* L, lldb::SBFrame* frame_sb)
{
SWIG_NewPointerObj(L, frame_sb, SWIGTYPE_p_lldb__SBFrame, 0);
}
void
PushSBClass (lua_State* L, lldb::SBBreakpointLocation* breakpoint_location_sb)
{
SWIG_NewPointerObj(L, breakpoint_location_sb, SWIGTYPE_p_lldb__SBBreakpointLocation, 0);
}

46
lldb/bindings/lua/lua-wrapper.swig Normal file
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@ -0,0 +1,46 @@
%header %{
template <typename T>
void
PushSBClass(lua_State* L, T* obj);
%}
%wrapper %{
// This function is called from Lua::CallBreakpointCallback
SWIGEXPORT llvm::Expected<bool>
LLDBSwigLuaBreakpointCallbackFunction
(
lua_State *L,
lldb::StackFrameSP stop_frame_sp,
lldb::BreakpointLocationSP bp_loc_sp
)
{
lldb::SBFrame sb_frame(stop_frame_sp);
lldb::SBBreakpointLocation sb_bp_loc(bp_loc_sp);
// Push the Lua wrappers
PushSBClass(L, &sb_frame);
PushSBClass(L, &sb_bp_loc);
// Call into the Lua callback passing 'sb_frame' and 'sb_bp_loc'.
// Expects a boolean return.
if (lua_pcall(L, 2, 1, 0) != LUA_OK) {
llvm::Error E = llvm::make_error<llvm::StringError>(
llvm::formatv("{0}\n", lua_tostring(L, -1)),
llvm::inconvertibleErrorCode());
// Pop error message from the stack.
lua_pop(L, 1);
return std::move(E);
}
// Boolean return from the callback
bool stop = lua_toboolean(L, -1);
lua_pop(L, 1);
return stop;
}
%}

4
lldb/bindings/lua/lua.swig
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@ -14,8 +14,12 @@
%include "headers.swig"
%{
#include "llvm/Support/Error.h"
#include "llvm/Support/FormatVariadic.h"
#include "../bindings/lua/lua-swigsafecast.swig"
using namespace lldb_private;
using namespace lldb;
%}
%include "interfaces.swig"
%include "lua-wrapper.swig"

48
lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
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@ -9,11 +9,34 @@
#include "Lua.h"
#include "lldb/Host/FileSystem.h"
#include "lldb/Utility/FileSpec.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FormatVariadic.h"
using namespace lldb_private;
using namespace lldb;
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
// Disable warning C4190: 'LLDBSwigPythonBreakpointCallbackFunction' has
// C-linkage specified, but returns UDT 'llvm::Expected<bool>' which is
// incompatible with C
#if _MSC_VER
#pragma warning (push)
#pragma warning (disable : 4190)
#endif
extern "C" llvm::Expected<bool>
LLDBSwigLuaBreakpointCallbackFunction(lua_State *L,
lldb::StackFrameSP stop_frame_sp,
lldb::BreakpointLocationSP bp_loc_sp);
#if _MSC_VER
#pragma warning (pop)
#endif
#pragma clang diagnostic pop
static int lldb_print(lua_State *L) {
int n = lua_gettop(L);
lua_getglobal(L, "io");
@ -57,6 +80,31 @@ llvm::Error Lua::Run(llvm::StringRef buffer) {
return e;
}
llvm::Error Lua::RegisterBreakpointCallback(void *baton, const char *body) {
lua_pushlightuserdata(m_lua_state, baton);
const char *fmt_str = "return function(frame, bp_loc, ...) {0} end";
std::string func_str = llvm::formatv(fmt_str, body).str();
if (luaL_dostring(m_lua_state, func_str.c_str()) != LUA_OK) {
llvm::Error e = llvm::make_error<llvm::StringError>(
llvm::formatv("{0}\n", lua_tostring(m_lua_state, -1)),
llvm::inconvertibleErrorCode());
// Pop error message from the stack.
lua_pop(m_lua_state, 2);
return e;
}
lua_settable(m_lua_state, LUA_REGISTRYINDEX);
return llvm::Error::success();
}
llvm::Expected<bool>
Lua::CallBreakpointCallback(void *baton, lldb::StackFrameSP stop_frame_sp,
lldb::BreakpointLocationSP bp_loc_sp) {
lua_pushlightuserdata(m_lua_state, baton);
lua_gettable(m_lua_state, LUA_REGISTRYINDEX);
return LLDBSwigLuaBreakpointCallbackFunction(m_lua_state, stop_frame_sp,
bp_loc_sp);
}
llvm::Error Lua::LoadModule(llvm::StringRef filename) {
FileSpec file(filename);
if (!FileSystem::Instance().Exists(file)) {

6
lldb/source/Plugins/ScriptInterpreter/Lua/Lua.h
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@ -9,6 +9,8 @@
#ifndef liblldb_Lua_h_
#define liblldb_Lua_h_
#include "lldb/API/SBBreakpointLocation.h"
#include "lldb/API/SBFrame.h"
#include "lldb/lldb-types.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Error.h"
@ -29,6 +31,10 @@ public:
~Lua();
llvm::Error Run(llvm::StringRef buffer);
llvm::Error RegisterBreakpointCallback(void *baton, const char *body);
llvm::Expected<bool>
CallBreakpointCallback(void *baton, lldb::StackFrameSP stop_frame_sp,
lldb::BreakpointLocationSP bp_loc_sp);
llvm::Error LoadModule(llvm::StringRef filename);
llvm::Error ChangeIO(FILE *out, FILE *err);

46
lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.cpp
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@ -8,14 +8,17 @@
#include "ScriptInterpreterLua.h"
#include "Lua.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/StreamFile.h"
#include "lldb/Interpreter/CommandReturnObject.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Utility/Stream.h"
#include "lldb/Utility/StringList.h"
#include "lldb/Utility/Timer.h"
#include "llvm/Support/FormatAdapters.h"
#include <memory>
using namespace lldb;
using namespace lldb_private;
@ -174,6 +177,49 @@ llvm::Error ScriptInterpreterLua::LeaveSession() {
return m_lua->Run(str);
}
bool ScriptInterpreterLua::BreakpointCallbackFunction(
void *baton, StoppointCallbackContext *context, user_id_t break_id,
user_id_t break_loc_id) {
assert(context);
ExecutionContext exe_ctx(context->exe_ctx_ref);
Target *target = exe_ctx.GetTargetPtr();
if (target == nullptr)
return true;
StackFrameSP stop_frame_sp(exe_ctx.GetFrameSP());
BreakpointSP breakpoint_sp = target->GetBreakpointByID(break_id);
BreakpointLocationSP bp_loc_sp(breakpoint_sp->FindLocationByID(break_loc_id));
Debugger &debugger = target->GetDebugger();
ScriptInterpreterLua *lua_interpreter = static_cast<ScriptInterpreterLua *>(
debugger.GetScriptInterpreter(true, eScriptLanguageLua));
Lua &lua = lua_interpreter->GetLua();
llvm::Expected<bool> BoolOrErr =
lua.CallBreakpointCallback(baton, stop_frame_sp, bp_loc_sp);
if (llvm::Error E = BoolOrErr.takeError()) {
debugger.GetErrorStream() << toString(std::move(E));
return true;
}
return *BoolOrErr;
}
Status ScriptInterpreterLua::SetBreakpointCommandCallback(
BreakpointOptions *bp_options, const char *command_body_text) {
Status error;
auto data_up = std::make_unique<CommandDataLua>();
error = m_lua->RegisterBreakpointCallback(data_up.get(), command_body_text);
if (error.Fail())
return error;
auto baton_sp =
std::make_shared<BreakpointOptions::CommandBaton>(std::move(data_up));
bp_options->SetCallback(ScriptInterpreterLua::BreakpointCallbackFunction,
baton_sp);
return error;
}
lldb::ScriptInterpreterSP
ScriptInterpreterLua::CreateInstance(Debugger &debugger) {
return std::make_shared<ScriptInterpreterLua>(debugger);

17
lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.h
View File

@ -10,11 +10,20 @@
#define liblldb_ScriptInterpreterLua_h_
#include "lldb/Interpreter/ScriptInterpreter.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-enumerations.h"
namespace lldb_private {
class Lua;
class ScriptInterpreterLua : public ScriptInterpreter {
public:
class CommandDataLua : public BreakpointOptions::CommandData {
public:
CommandDataLua() : BreakpointOptions::CommandData() {
interpreter = lldb::eScriptLanguageLua;
}
};
ScriptInterpreterLua(Debugger &debugger);
~ScriptInterpreterLua() override;
@ -41,6 +50,11 @@ public:
static const char *GetPluginDescriptionStatic();
static bool BreakpointCallbackFunction(void *baton,
StoppointCallbackContext *context,
lldb::user_id_t break_id,
lldb::user_id_t break_loc_id);
// PluginInterface protocol
lldb_private::ConstString GetPluginName() override;
@ -51,6 +65,9 @@ public:
llvm::Error EnterSession(lldb::user_id_t debugger_id);
llvm::Error LeaveSession();
Status SetBreakpointCommandCallback(BreakpointOptions *bp_options,
const char *command_body_text) override;
private:
std::unique_ptr<Lua> m_lua;
bool m_session_is_active = false;

18
lldb/test/Shell/ScriptInterpreter/Lua/breakpoint_oneline_callback.test Normal file
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@ -0,0 +1,18 @@
# REQUIRES: lua
# RUN: echo "int main() { return 0; }" | %clang_host -x c - -o %t
# RUN: %lldb -s %s --script-language lua %t 2>&1 | FileCheck %s
b main
breakpoint command add -s lua -o 'return false'
run
# CHECK: Process {{[0-9]+}} exited with status = 0
breakpoint command add -s lua -o 'print(bacon)'
run
# CHECK: bacon
# CHECK: Process {{[0-9]+}} exited with status = 0
breakpoint command add -s lua -o "return true"
run
# CHECK: Process {{[0-9]+}} stopped
breakpoint command add -s lua -o 'error("my error message")'
run
# CHECK: my error message
# CHECK: Process {{[0-9]+}} stopped

24
lldb/unittests/ScriptInterpreter/Lua/LuaTests.cpp
View File

@ -13,6 +13,30 @@ using namespace lldb_private;
extern "C" int luaopen_lldb(lua_State *L) { return 0; }
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
// Disable warning C4190: 'LLDBSwigPythonBreakpointCallbackFunction' has
// C-linkage specified, but returns UDT 'llvm::Expected<bool>' which is
// incompatible with C
#if _MSC_VER
#pragma warning (push)
#pragma warning (disable : 4190)
#endif
extern "C" llvm::Expected<bool>
LLDBSwigLuaBreakpointCallbackFunction(lua_State *L,
lldb::StackFrameSP stop_frame_sp,
lldb::BreakpointLocationSP bp_loc_sp) {
return false;
}
#if _MSC_VER
#pragma warning (pop)
#endif
#pragma clang diagnostic pop
TEST(LuaTest, RunValid) {
Lua lua;
llvm::Error error = lua.Run("foo = 1");