[Feature #20290] Add API for C extensions to free memory

common.mk

@@ -7207,6 +7207,7 @@ gc.$(OBJEXT): $(top_srcdir)/internal/gc.h
 gc.$(OBJEXT): $(top_srcdir)/internal/hash.h
 gc.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 gc.$(OBJEXT): $(top_srcdir)/internal/io.h
+gc.$(OBJEXT): $(top_srcdir)/internal/load.h
 gc.$(OBJEXT): $(top_srcdir)/internal/numeric.h
 gc.$(OBJEXT): $(top_srcdir)/internal/object.h
 gc.$(OBJEXT): $(top_srcdir)/internal/proc.h

configure.ac

@@ -1738,7 +1738,7 @@ AS_IF([test "$GCC" = yes], [
 AC_CACHE_CHECK(for exported function attribute, rb_cv_func_exported, [
 rb_cv_func_exported=no
 RUBY_WERROR_FLAG([
-for mac in '__attribute__ ((__visibility__("default")))' '__declspec(dllexport)'; do
+for mac in '__declspec(dllexport)' '__attribute__ ((__visibility__("default")))'; do
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@define RUBY_FUNC_EXPORTED $mac extern
     RUBY_FUNC_EXPORTED void conftest_attribute_check(void);]], [[]])],
     [rb_cv_func_exported="$mac"; break])

dln.c

@@ -540,3 +540,26 @@ dln_load(const char *file)
 
     return 0;			/* dummy return */
 }
+
+#define DESTRUCT_FUNC_PREFIX EXTERNAL_PREFIX"Destruct_"
+
+void
+dln_unload(const char *file, void *handle)
+{
+#if defined(_WIN32) || defined(USE_DLN_DLOPEN)
+    struct string_part extname = init_funcname_len(file);
+    const size_t plen = sizeof(DESTRUCT_FUNC_PREFIX) - 1;
+    char *const destruct_func_name = ALLOCA_N(char, plen + extname.len + 1);
+    memcpy(destruct_func_name, DESTRUCT_FUNC_PREFIX, plen);
+    memcpy(destruct_func_name + plen, extname.ptr, extname.len);
+    destruct_func_name[plen + extname.len] = '\0';
+
+    void *symbol = dln_sym(handle, destruct_func_name);
+
+    if (symbol) {
+        ((void (*)(void))symbol)();
+    }
+#else
+    dln_notimplement();
+#endif
+}

dln.h

@@ -26,6 +26,7 @@ char *dln_find_exe_r(const char*,const char*,char*,size_t DLN_FIND_EXTRA_ARG_DEC
 char *dln_find_file_r(const char*,const char*,char*,size_t DLN_FIND_EXTRA_ARG_DECL);
 void *dln_load(const char*);
 void *dln_symbol(void*,const char*);
+void dln_unload(const char *file, void *handle);
 
 RUBY_SYMBOL_EXPORT_END
 

dmydln.c

@@ -20,3 +20,9 @@ dln_symbol(void *handle, const char *symbol)
 
     UNREACHABLE_RETURN(NULL);
 }
+
+NORETURN(void dln_unload(const char *file, void *handle));
+void dln_unload(const char *file, void *handle)
+{
+    rb_loaderror("this executable file can't load extension libraries");
+}

ext/-test-/load/destruct/destruct.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <ruby/ruby.h>
+
+void
+Init_destruct(void)
+{}
+
+RUBY_FUNC_EXPORTED void
+Destruct_destruct(void)
+{
+    printf("Calling Destruct_destruct\n");
+}

ext/-test-/load/destruct/extconf.rb

@@ -0,0 +1 @@
+create_makefile("-test-/load/destruct")

gc.c

@@ -119,6 +119,7 @@
 #include "internal/hash.h"
 #include "internal/imemo.h"
 #include "internal/io.h"
+#include "internal/load.h"
 #include "internal/numeric.h"
 #include "internal/object.h"
 #include "internal/proc.h"
@@ -4275,7 +4276,6 @@ rb_objspace_free_objects(rb_objspace_t *objspace)
     }
 }
 
-
 void
 rb_objspace_call_finalizer(rb_objspace_t *objspace)
 {
@@ -4340,14 +4340,7 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
               case T_FILE:
                 obj_free(objspace, vp);
                 break;
-              case T_SYMBOL:
-              case T_ARRAY:
-              case T_NONE:
-                break;
               default:
-                if (rb_free_at_exit) {
-                    obj_free(objspace, vp);
-                }
                 break;
             }
             if (poisoned) {
@@ -4359,6 +4352,38 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
 
     gc_exit(objspace, gc_enter_event_finalizer, &lock_lev);
 
+    if (rb_free_at_exit) {
+        rb_ext_call_destruct();
+
+        for (i = 0; i < heap_allocated_pages; i++) {
+            struct heap_page *page = heap_pages_sorted[i];
+            short stride = page->slot_size;
+
+            uintptr_t p = (uintptr_t)page->start;
+            uintptr_t pend = p + page->total_slots * stride;
+            for (; p < pend; p += stride) {
+                VALUE vp = (VALUE)p;
+                void *poisoned = asan_unpoison_object_temporary(vp);
+                switch (BUILTIN_TYPE(vp)) {
+                  case T_DATA:
+                  case T_FILE:
+                  case T_SYMBOL:
+                  case T_ARRAY:
+                  case T_NONE:
+                  case T_ZOMBIE:
+                    break;
+                  default:
+                    obj_free(objspace, vp);
+                    break;
+                }
+                if (poisoned) {
+                    GC_ASSERT(BUILTIN_TYPE(vp) == T_NONE);
+                    asan_poison_object(vp);
+                }
+            }
+        }
+    }
+
     finalize_deferred_heap_pages(objspace);
 
     st_free_table(finalizer_table);

include/ruby/internal/dllexport.h

@@ -54,7 +54,11 @@
 #endif
 
 #ifndef RUBY_FUNC_EXPORTED
-# define RUBY_FUNC_EXPORTED /* void */
+# ifdef _WIN32
+#  define RUBY_FUNC_EXPORTED __declspec(dllexport)
+# else
+#  define RUBY_FUNC_EXPORTED /* void */
+# endif
 #endif
 
 /** @endcond */

internal/load.h

@@ -14,5 +14,6 @@
 VALUE rb_get_expanded_load_path(void);
 int rb_require_internal(VALUE fname);
 NORETURN(void rb_load_fail(VALUE, const char*));
+void rb_ext_call_destruct(void);
 
 #endif /* INTERNAL_LOAD_H */

load.c

@@ -1580,6 +1580,20 @@ rb_ext_resolve_symbol(const char* fname, const char* symbol)
     return dln_symbol((void *)NUM2SVALUE(handle), symbol);
 }
 
+static int
+rb_ext_call_destruct_i(VALUE path, VALUE handle, VALUE _arg)
+{
+    dln_unload(RSTRING_PTR(path), (void *)NUM2SVALUE(handle));
+
+    return ST_CONTINUE;
+}
+
+void
+rb_ext_call_destruct(void)
+{
+    rb_hash_foreach(ruby_dln_libmap, rb_ext_call_destruct_i, 0);
+}
+
 void
 Init_load(void)
 {

parse.y

@@ -1616,7 +1616,7 @@ static void numparam_pop(struct parser_params *p, NODE *prev_inner);
 #define RE_OPTION_ARG_ENCODING_NONE 32
 
 #define yytnamerr(yyres, yystr) (YYSIZE_T)rb_yytnamerr(p, yyres, yystr)
-size_t rb_yytnamerr(struct parser_params *p, char *yyres, const char *yystr);
+RUBY_FUNC_EXPORTED size_t rb_yytnamerr(struct parser_params *p, char *yyres, const char *yystr);
 
 #define TOKEN2ID(tok) ( \
     tTOKEN_LOCAL_BEGIN<(tok)&&(tok)<tTOKEN_LOCAL_END ? TOKEN2LOCALID(tok) : \

prism/extension.h

@@ -13,6 +13,6 @@ VALUE pm_ast_new(const pm_parser_t *parser, const pm_node_t *node, rb_encoding *
 
 void Init_prism_api_node(void);
 void Init_prism_pack(void);
-PRISM_EXPORTED_FUNCTION void Init_prism(void);
+RUBY_FUNC_EXPORTED void Init_prism(void);
 
 #endif

test/-ext-/load/test_destruct.rb

@@ -0,0 +1,11 @@
+require "test/unit"
+
+class TestDestruct < Test::Unit::TestCase
+  def test_destruct_func_not_called
+    assert_in_out_err(["-r-test-/load/destruct"], "", [])
+  end
+
+  def test_destruct_func_called_when_free_on_exit
+    assert_in_out_err([{"RUBY_FREE_AT_EXIT" => "1"}, "-W0", "-r-test-/load/destruct"], "puts 'Running Ruby'", ["Running Ruby", "Calling Destruct_destruct"])
+  end
+end