clean up the call stack in a scoped way properly always

src/cs_util.hh

@@ -2,6 +2,8 @@
 #define LIBCUBESCRIPT_CS_UTIL_HH
 
 #include <ostd/string.hh>
+#include <ostd/utility.hh>
+#include <ostd/type_traits.hh>
 
 namespace cscript {
 
@@ -13,6 +15,22 @@ CsFloat cs_parse_float(
     ostd::ConstCharRange input, ostd::ConstCharRange *end = nullptr
 );
 
+template<typename F>
+struct CsScopeExit {
+    template<typename FF>
+    CsScopeExit(FF &&f): func(ostd::forward<FF>(f)) {}
+    ~CsScopeExit() {
+        func();
+    }
+    ostd::Decay<F> func;
+};
+
+template<typename F1, typename F2>
+inline void cs_do_and_cleanup(F1 &&dof, F2 &&clf) {
+    CsScopeExit<F2> cleanup(ostd::forward<F2>(clf));
+    dof();
+}
+
 } /* namespace cscript */
 
 #endif /* LIBCUBESCRIPT_CS_UTIL_HH */

src/cs_vm.cc

@@ -443,7 +443,9 @@ static inline void cs_call_alias(
         CsAliasInternal::compile_code(a, cs)
     );
     bcode_incr(codep);
+    cs_do_and_cleanup([&]() {
         runcode(cs, codep+1, result);
+    }, [&]() {
         bcode_decr(codep);
         cs.p_callstack = aliaslink.next;
         cs.identflags = oldflags;
@@ -462,6 +464,7 @@ static inline void cs_call_alias(
         force_arg(result, op & CsCodeRetMask);
         anargs->set_value(oldargs);
         nargs = offset - skip;
+    });
 }
 
 static constexpr int MaxRunDepth = 255;
@@ -631,10 +634,13 @@ static ostd::Uint32 *runcode(CsState &cs, ostd::Uint32 *code, CsValue &result) {
                 for (int i = 0; i < numlocals; ++i) {
                     cs_push_alias(args[offset + i].get_ident(), locals[i]);
                 }
+                cs_do_and_cleanup([&]() {
                     code = runcode(cs, code, result);
+                }, [&]() {
                     for (int i = offset; i < numargs; i++) {
                         cs_pop_alias(args[i].get_ident());
                     }
+                });
                 goto exit;
             }
 
@@ -1448,10 +1454,13 @@ noid:
                                 args[offset + j]
                             ), locals[j]);
                         }
+                        cs_do_and_cleanup([&]() {
                             code = runcode(cs, code, result);
+                        }, [&]() {
                             for (ostd::Size j = 0; j < ostd::Size(callargs); ++j) {
                                 cs_pop_alias(args[offset + j].get_ident());
                             }
+                        });
                         goto exit;
                     }
                     case CsIdIvar:

src/cs_vm.hh

@@ -8,6 +8,8 @@
 #include <ostd/array.hh>
 #include <ostd/vector.hh>
 
+#include "cs_util.hh"
+
 namespace cscript {
 
 static constexpr int MaxArguments = 25;
@@ -328,7 +330,7 @@ static void cs_do_args(CsState &cs, F body) {
         cs.p_callstack->id, cs.p_callstack, prevstack->usedargs, prevstack->argstack
     };
     cs.p_callstack = &aliaslink;
-    body();
+    cs_do_and_cleanup(ostd::move(body), [&]() {
         prevstack->usedargs = aliaslink.usedargs;
         cs.p_callstack = aliaslink.next;
         int argmask2 = cs.p_callstack->usedargs;
@@ -339,6 +341,7 @@ static void cs_do_args(CsState &cs, F body) {
                 );
             }
         }
+    });
 }
 
 CsBytecode *cs_copy_code(CsBytecode *c);