[lldb/lua] Add scripted watchpoints for Lua

Add support for Lua scripted watchpoints, with basic tests.

Differential Revision: https://reviews.llvm.org/D105034

1 files changed, 29 insertions, 0 deletions

diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
index f14e273..e99b7b8 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
@@ -30,6 +30,9 @@ extern "C" llvm::Expected<bool> LLDBSwigLuaBreakpointCallbackFunction(
     lua_State *L, lldb::StackFrameSP stop_frame_sp,
     lldb::BreakpointLocationSP bp_loc_sp, StructuredDataImpl *extra_args_impl);
 
+extern "C" llvm::Expected<bool> LLDBSwigLuaWatchpointCallbackFunction(
+    lua_State *L, lldb::StackFrameSP stop_frame_sp, lldb::WatchpointSP wp_sp);
+
 #if _MSC_VER
 #pragma warning (pop)
 #endif
@@ -113,6 +116,32 @@ Lua::CallBreakpointCallback(void *baton, lldb::StackFrameSP stop_frame_sp,
                                                bp_loc_sp, extra_args_impl);
 }
 
+llvm::Error Lua::RegisterWatchpointCallback(void *baton, const char *body) {
+  lua_pushlightuserdata(m_lua_state, baton);
+  const char *fmt_str = "return function(frame, wp, ...) {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}", 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::CallWatchpointCallback(void *baton, lldb::StackFrameSP stop_frame_sp,
+                            lldb::WatchpointSP wp_sp) {
+
+  lua_pushlightuserdata(m_lua_state, baton);
+  lua_gettable(m_lua_state, LUA_REGISTRYINDEX);
+  return LLDBSwigLuaWatchpointCallbackFunction(m_lua_state, stop_frame_sp,
+                                               wp_sp);
+}
+
 llvm::Error Lua::CheckSyntax(llvm::StringRef buffer) {
   int error =
       luaL_loadbuffer(m_lua_state, buffer.data(), buffer.size(), "buffer");