lldb: add lua builtin scripts for Unreal Engine debugging

Signed-off-by: hexian000 <hexian000@outlook.com>

lldb/include/lldb/lldb-enumerations.h

@@ -219,7 +219,7 @@ enum ScriptLanguage {
   eScriptLanguagePython,
   eScriptLanguageLua,
   eScriptLanguageUnknown,
-  eScriptLanguageDefault = eScriptLanguagePython
+  eScriptLanguageDefault = eScriptLanguageLua
 };
 
 /// Register numbering types.

lldb/source/API/CMakeLists.txt

@@ -20,7 +20,7 @@ if(LLDB_ENABLE_LUA)
   set(lldb_lua_wrapper ${lua_bindings_dir}/LLDBWrapLua.cpp)
 endif()
 
-add_lldb_library(liblldb SHARED ${option_framework}
+add_lldb_library(liblldb STATIC ${option_framework}
   SBAddress.cpp
   SBAttachInfo.cpp
   SBBlock.cpp

lldb/source/Plugins/ScriptInterpreter/Lua/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_lldb_library(lldbPluginScriptInterpreterLua PLUGIN
   Lua.cpp
+  LuaBuiltin.cpp
   ScriptInterpreterLua.cpp
 
   LINK_LIBS

lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp

@@ -37,6 +37,8 @@ Lua::Lua() : m_lua_state(luaL_newstate()) {
   luaopen_lldb(m_lua_state);
   lua_pushcfunction(m_lua_state, lldb_print);
   lua_setglobal(m_lua_state, "print");
+
+  luaL_dostring(m_lua_state, m_builtin);
 }
 
 Lua::~Lua() {

lldb/source/Plugins/ScriptInterpreter/Lua/Lua.h

@@ -47,6 +47,7 @@ class Lua {
 
 private:
   lua_State *m_lua_state;
+  static const char m_builtin[];
 };
 
 } // namespace lldb_private

lldb/source/Plugins/ScriptInterpreter/Lua/LuaBuiltin.cpp

@@ -0,0 +1,103 @@
+#include "Lua.h"
+
+namespace lldb_private {
+
+const char Lua::m_builtin[] = u8R"Lua(
+local function prepare()
+    lldb.debugger = lldb.SBDebugger.FindDebuggerWithID(1)
+    lldb.target = lldb.debugger:GetSelectedTarget()
+    lldb.process = lldb.target:GetProcess()
+    lldb.thread = lldb.process:GetSelectedThread()
+    lldb.frame = lldb.thread:GetSelectedFrame()
+end
+
+local function printf(s, ...)
+    print(string.format(s, ...))
+end
+
+local function cmdf(s, ...)
+    local cmd = string.format(s, ...)
+    local ret = lldb.SBCommandReturnObject()
+    local interpreter = lldb.debugger:GetCommandInterpreter()
+    interpreter:HandleCommand(cmd, ret)
+    if not ret:Succeeded() then
+        lldb.debugger:GetErrorFile():Flush()
+        local err = string.gsub(ret:GetError(), "\n$", "")
+        error(err)
+    end
+    lldb.debugger:GetOutputFile():Flush()
+    local out = string.gsub(ret:GetOutput(), "\n$", "")
+    return out
+end
+
+local function evalf(ctx, s, ...)
+    local expr = string.format(s, ...)
+    local value = ctx:EvaluateExpression(expr)
+    if not value:IsValid() then
+        error("failed evaluating: " .. expr)
+    end
+    return value:GetValue()
+end
+
+local function read_string(ctx, expr, len)
+    local value = ctx:EvaluateExpression(expr)
+    local err = lldb.SBError()
+    local process = value:GetProcess()
+    local buf = process:ReadCStringFromMemory(tonumber(value:GetValue()), len + 1, err)
+    if not err:Success() then
+        error(err:GetCString())
+    end
+    -- printf("read_string: [%d] %q", len, buf)
+    return buf
+end
+
+unreal = {}
+
+function unreal.pname(index)
+    pcall(prepare)
+    local ctx = lldb.target
+    local shift = tonumber(evalf(ctx, "FNameDebugVisualizer::OffsetBits"))
+    local mask = tonumber(evalf(ctx, "FNameDebugVisualizer::OffsetMask"))
+    local stride = tonumber(evalf(ctx, "FNameDebugVisualizer::EntryStride"))
+    local i = index >> shift
+    local j = (index & mask) * stride
+    local entry = evalf(ctx, "&GNameBlocksDebug[%d][%d]", i, j)
+    -- printf("entry = %q", entry)
+    local len = tonumber(evalf(ctx, "((FNameEntry*)%s)->Header.Len", entry))
+    -- printf("len = %d", len)
+    local name = read_string(ctx, string.format("&((FNameEntry*)%s)->AnsiName", entry), len)
+    printf("FName(%d) = %q", index, name)
+end
+
+function unreal.pweak(index)
+    pcall(prepare)
+    local chunk = 65536
+    local i = index // chunk
+    local j = index % chunk
+    print(cmdf("print GUObjectArray.ObjObjects.Objects[%d][%d]", i, j))
+end
+
+function unreal.ptype(ptr)
+    pcall(prepare)
+    local vtable = tonumber(evalf(lldb.target, string.format("*(void**)0x%x", ptr)))
+    printf("vtable: 0x%x", vtable)
+    print(cmdf("target modules lookup -a 0x%x", vtable))
+end
+
+function unreal.vtable(vtable)
+    pcall(prepare)
+    local size = tonumber(evalf(lldb.target, "sizeof(void*)"))
+    for i = 0, 999 do
+        local vfunc = vtable + (i * size)
+        local line = cmdf("memory read -c 1 -f A 0x%x", vfunc)
+        local ptr = select(3, string.find(line, "^%s*%w+:%s+(%w+)"))
+        if tonumber(ptr) == 0 then
+            break
+        end
+        print(line)
+    end
+end
+
+)Lua";
+
+} // namespace lldb_private

lldb/tools/driver/CMakeLists.txt

@@ -17,6 +17,8 @@ add_lldb_tool(lldb
 
   LINK_LIBS
     liblldb
+    lldbPluginScriptInterpreterLua # hack for GNU ld
+    liblldb
 
   LINK_COMPONENTS
     Option

lldb/tools/driver/Driver.cpp

@@ -261,6 +261,8 @@ SBError Driver::ProcessArgs(const opt::InputArgList &args, bool &exiting) {
   if (auto *arg = args.getLastArg(OPT_script_language)) {
     auto *arg_value = arg->getValue();
     m_debugger.SetScriptLanguage(m_debugger.GetScriptingLanguage(arg_value));
+  } else {
+    m_debugger.SetScriptLanguage(lldb::ScriptLanguage::eScriptLanguageDefault);
   }
 
   if (args.hasArg(OPT_source_quietly)) {