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

tammela · tammela · commit a0d7406ae800 · 2020-11-30T14:12:26.000Z
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
diff --git a/lldb/bindings/lua/lua-swigsafecast.swig b/lldb/bindings/lua/lua-swigsafecast.swig
@@ -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);
+}
diff --git a/lldb/bindings/lua/lua-wrapper.swig b/lldb/bindings/lua/lua-wrapper.swig
@@ -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;
+}
+
+
+%}
diff --git a/lldb/bindings/lua/lua.swig b/lldb/bindings/lua/lua.swig
@@ -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"
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
@@ -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)) {
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.h b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.h
@@ -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 @@ class Lua {
   ~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);
 
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.cpp b/lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.cpp
@@ -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);
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.h b/lldb/source/Plugins/ScriptInterpreter/Lua/ScriptInterpreterLua.h
@@ -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 @@ class ScriptInterpreterLua : public ScriptInterpreter {
 
   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 @@ class ScriptInterpreterLua : public ScriptInterpreter {
   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;
diff --git a/lldb/test/Shell/ScriptInterpreter/Lua/breakpoint_oneline_callback.test b/lldb/test/Shell/ScriptInterpreter/Lua/breakpoint_oneline_callback.test
@@ -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
diff --git a/lldb/unittests/ScriptInterpreter/Lua/LuaTests.cpp b/lldb/unittests/ScriptInterpreter/Lua/LuaTests.cpp
@@ -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");
