✨ add limited execution mode

src/main.cpp

@@ -30,6 +30,7 @@ const u32 VM_SYMINFO   = 1<<7;
 const u32 VM_PROFILE   = 1<<8;
 const u32 VM_PROF_ALL  = 1<<9;
 const u32 VM_REF_FILE  = 1<<10;
+const u32 VM_LIMIT     = 1<<11;
 
 std::ostream& help(std::ostream& out) {
     out
@@ -59,6 +60,7 @@ std::ostream& help(std::ostream& out) {
     << "         --prof     | show profiling result, available in debug mode.\n"
     << "         --prof-all | show profiling result of all files,"
     << "available under debug mode.\n"
+    << "         --limit    | use limited execution mode."
     << "file:\n"
     << "   <filename>       | execute file.\n"
     << "argv:\n"
@@ -155,7 +157,7 @@ void execute(
     }
 
     // code generator gets parser's ast and import file list to generate code
-    gen.compile(parse, ld, false).chkerr();
+    gen.compile(parse, ld, false, cmd&VM_LIMIT).chkerr();
     if (cmd&VM_CODE) {
         gen.print(std::cout);
     }
@@ -171,6 +173,7 @@ void execute(
     } else if (cmd&VM_TIME || cmd&VM_EXEC) {
         auto runtime = std::unique_ptr<nasal::vm>(new nasal::vm);
         runtime->set_detail_report_info(cmd&VM_DETAIL);
+        runtime->set_limit_mode_flag(cmd&VM_LIMIT);
         runtime->run(gen, ld, argv);
     }
 
@@ -227,7 +230,8 @@ i32 main(i32 argc, const char* argv[]) {
         {"--prof", VM_PROFILE},
         {"--prof-all", VM_PROF_ALL},
         {"-f", VM_REF_FILE},
-        {"--ref-file", VM_REF_FILE}
+        {"--ref-file", VM_REF_FILE},
+        {"--limit", VM_LIMIT|VM_EXEC}
     };
     u32 cmd = 0;
     std::string filename = "";

src/nasal_builtin.cpp

@@ -3,6 +3,13 @@
 
 namespace nasal {
 
+var builtin_unsafe(context* ctx, gc* ngc) {
+    return nas_err(
+        "unsafe_redirect",
+        "you are using unsafe system api under limited mode!"
+    );
+}
+
 var builtin_print(context* ctx, gc* ngc) {
     for(auto& i : ctx->localr[1].vec().elems) {
         std::cout << i;

src/nasal_builtin.h

@@ -29,6 +29,7 @@
 
 namespace nasal {
 
+var builtin_unsafe(context*, gc*);
 var builtin_print(context*, gc*);
 var builtin_println(context*, gc*);
 var builtin_exit(context*, gc*);

src/nasal_codegen.cpp

@@ -11,12 +11,18 @@ void codegen::init_file_map(const std::vector<std::string>& file_list) {
 
 void codegen::load_native_function_table(nasal_builtin_table* table) {
     for(usize i = 0; table[i].func; ++i) {
+        // check confliction
         if (native_function_mapper.count(table[i].name)) {
             err.err("code", "\"" + std::string(table[i].name) + "\" conflicts.");
             continue;
         }
+        if (flag_limited_mode && unsafe_system_api.count(table[i].name)) {
+            native_function.push_back({"__unsafe_redirect", builtin_unsafe});
+        } else {
             native_function.push_back(table[i]);
+        }
         auto index = native_function_mapper.size();
+        // insert into mapper
         native_function_mapper[table[i].name] = index;
     }
 }
@@ -1302,10 +1308,14 @@ void codegen::ret_gen(return_expr* node) {
     emit(op_ret, 0, node->get_location());
 }
 
-const error& codegen::compile(parse& parse, linker& import, bool repl_flag) {
+const error& codegen::compile(parse& parse,
+                              linker& import,
+                              bool repl_flag,
+                              bool limit_mode) {
+    need_repl_output = repl_flag;
+    flag_limited_mode = limit_mode;
     init_native_function();
     init_file_map(import.get_file_list());
-    need_repl_output = repl_flag;
 
     in_foreach_loop_level.push_back(0);
 

src/nasal_codegen.h

@@ -37,6 +37,24 @@ private:
 
     // repl output flag, will generate op_repl to output stack top value if true
     bool need_repl_output;
+    // limit mode flag
+    bool flag_limited_mode;
+    const std::unordered_set<std::string> unsafe_system_api = {
+        // builtin
+        "__system", "__input",
+        // io
+        "__fout", "__open", "__write", "__stat"
+        // bits
+        "__fld", "__sfld", "__setfld",
+        "__buf",
+        // fg
+        "__logprint",
+        // dylib
+        "__dlopen", "__dlclose", "__dlcallv", "__dlcall",
+        // unix
+        "__pipe", "__fork", "__waitpid", "__chdir",
+        "__environ", "__getcwd", "__getenv"
+    };
 
     // file mapper for file -> index
     std::unordered_map<std::string, usize> file_map;
@@ -141,7 +159,7 @@ public:
 
 public:
     codegen() = default;
-    const error& compile(parse&, linker&, bool);
+    const error& compile(parse&, linker&, bool, bool);
     void print(std::ostream&);
     void symbol_dump(std::ostream&) const;
 };

src/nasal_import.cpp

@@ -188,6 +188,7 @@ code_block* linker::import_regular_file(
     check_exist_or_record_file(filename);
 
     module_load_stack.push_back(filename);
+    // avoid stack overflow
     if (module_load_stack.size()>MAX_RECURSION_DEPTH) {
         err.err("link",
             node->get_location(),
@@ -258,6 +259,7 @@ code_block* linker::import_nasal_lib() {
 }
 
 std::string linker::generate_module_name(const std::string& file_path) {
+    // import("...") may trigger this error module name
     auto error_name = "module@[" + file_path + "]";
     if (!file_path.length()) {
         return error_name;
@@ -332,13 +334,19 @@ return_expr* linker::generate_module_return(code_block* block) {
 }
 
 definition_expr* linker::generate_module_definition(code_block* block) {
+    // generate ast node like this:
+    // var {module_name} = (func() {
+    //     ... # module itself
+    // })();
     auto def = new definition_expr(block->get_location());
     def->set_identifier(new identifier(
         block->get_location(),
         generate_module_name(block->get_location().file)
     ));
     
+    // (func() {...})();
     auto call = new call_expr(block->get_location());
+    // func() {...}
     auto func = new function(block->get_location());
     func->set_code_block(block);
     func->get_code_block()->add_expression(generate_module_return(block));
@@ -392,8 +400,11 @@ const error& linker::link(parse& parse, bool spath = false) {
     // then generate a new ast and return to import_ast
     // dfs load file
     auto library = import_nasal_lib();
+    // load used modules of this file
     load(parse.tree(), this_file);
+    // then insert the whole tree into library tree root
     merge_tree(library, parse.tree());
+    // swap tree root, and delete old root
     delete parse.swap(library);
     return err;
 }

src/nasal_vm.h

@@ -45,6 +45,9 @@ protected:
     bool first_exec_flag = true;
     bool allow_repl_output = false;
 
+    /* limited mode, will not load unsafe system api if switch on */
+    bool flag_limited_mode = false;
+
     /* vm initializing function */
     void init(
         const std::vector<std::string>&,
@@ -192,6 +195,8 @@ public:
     void set_repl_mode_flag(bool flag) {is_repl_mode = flag;}
     /* set repl output flag */
     void set_allow_repl_output_flag(bool flag) {allow_repl_output = flag;}
+    /* set limit mode flag */
+    void set_limit_mode_flag(bool flag) {flag_limited_mode = flag;}
 };
 
 inline bool vm::cond(var& val) {

src/repl.cpp

@@ -97,7 +97,7 @@ bool repl::run() {
     }
 
     nasal_opt->do_optimization(nasal_parser->tree());
-    if (nasal_codegen->compile(*nasal_parser, *nasal_linker, true).geterr()) {
+    if (nasal_codegen->compile(*nasal_parser, *nasal_linker, true, false).geterr()) {
         return false;
     }