Allow editing the key SV in uvar callbacks by passing a new option 'copy_key'

[perl/modules/Variable-Magic.git] / Magic.xs

diff --git a/Magic.xs b/Magic.xs
index 820d249a730f7590166a50dccfa39476578e263c..44d6c88202bc9e33377153cbdb6260953d0126f2 100644 (file)
--- a/Magic.xs
+++ b/Magic.xs
@@ -568,17 +568,32 @@ STATIC int vmg_svt_clear(pTHX_ SV *sv, MAGIC *mg) {
 }
 
 STATIC int vmg_svt_free(pTHX_ SV *sv, MAGIC *mg) {
+ SV *wiz = (SV *) mg->mg_ptr;
+ int ret = 0;
+
+ /* This may happen in global destruction */
+ if (SvTYPE(wiz) == SVTYPEMASK)
+  return 0;
+
  /* So that it can survive tmp cleanup in vmg_cb_call */
  SvREFCNT_inc(sv);
+
 #if !VMG_HAS_PERL_MAINT(5, 11, 0, 32686)
  /* The previous magic tokens were freed but the magic chain wasn't updated, so
   * if you access the sv from the callback the old deleted magics will trigger
   * and cause memory misreads. Change 32686 solved it that way : */
  SvMAGIC_set(sv, mg);
 #endif
+
  /* Perl_mg_free will get rid of the magic and decrement mg->mg_obj and
   * mg->mg_ptr reference count */
- return vmg_cb_call1e(SV2MGWIZ(mg->mg_ptr)->cb_free, sv, mg->mg_obj);
+ ret = vmg_cb_call1e(SV2MGWIZ(wiz)->cb_free, sv, mg->mg_obj);
+
+ /* Calling SvREFCNT_dec() will trigger destructors in an infinite loop, so
+  * we have to rely on SvREFCNT() being a lvalue. Heck, even the core does it */
+ --SvREFCNT(sv);
+
+ return ret;
 }
 
 #if MGf_COPY
@@ -623,13 +638,13 @@ STATIC int vmg_svt_local(pTHX_ SV *nsv, MAGIC *mg) {
 #if VMG_UVAR
 STATIC I32 vmg_svt_val(pTHX_ IV action, SV *sv) {
  struct ufuncs *uf;
- MAGIC *mg;
- SV *key = NULL;
+ MAGIC *mg, *umg;
+ SV *key = NULL, *newkey = NULL;
 
- mg  = mg_find(sv, PERL_MAGIC_uvar);
- /* mg can't be NULL or we wouldn't be there. */
- key = mg->mg_obj;
- uf  = (struct ufuncs *) mg->mg_ptr;
+ umg = mg_find(sv, PERL_MAGIC_uvar);
+ /* umg can't be NULL or we wouldn't be there. */
+ key = umg->mg_obj;
+ uf  = (struct ufuncs *) umg->mg_ptr;
 
  if (uf[1].uf_val != NULL) { uf[1].uf_val(aTHX_ action, sv); }
  if (uf[1].uf_set != NULL) { uf[1].uf_set(aTHX_ action, sv); }
@@ -641,7 +656,13 @@ STATIC I32 vmg_svt_val(pTHX_ IV action, SV *sv) {
    || (mg->mg_private < SIG_MIN)
    || (mg->mg_private > SIG_MAX)) { continue; }
   w = SV2MGWIZ(mg->mg_ptr);
-  if (!w->uvar) { continue; }
+  switch (w->uvar) {
+   case 0:
+    continue;
+   case 2:
+    if (!newkey)
+     newkey = key = umg->mg_obj = sv_2mortal(newSVsv(umg->mg_obj));
+  }
   switch (action) {
    case 0:
     if (w->cb_fetch)  { vmg_cb_call2(w->cb_fetch,  sv, mg->mg_obj, key); }
@@ -670,7 +691,7 @@ STATIC int vmg_wizard_free(pTHX_ SV *wiz, MAGIC *mg) {
  char buf[8];
  MGWIZ *w;
 
- if (PL_dirty) /* during global destruction, the context is already freed */
+ if (PL_dirty) /* During global destruction, the context is already freed */
   return 0;
 
  w = SV2MGWIZ(wiz);
@@ -955,7 +976,7 @@ CODE:
               + 1
 #endif /* MGf_LOCAL */
 #if VMG_UVAR
-              + 4
+              + 5
 #endif /* VMG_UVAR */
               ) { croak(vmg_wrongargnum); }
 
@@ -998,16 +1019,17 @@ CODE:
  VMG_SET_CB(ST(i++), store);
  VMG_SET_CB(ST(i++), exists);
  VMG_SET_CB(ST(i++), delete);
+ cb = ST(i++);
+ if (w->cb_fetch || w->cb_store || w->cb_exists || w->cb_delete)
+  w->uvar = SvTRUE(cb) ? 2 : 1;
+ else
+  w->uvar = 0;
 #endif /* VMG_UVAR */
 #if VMG_MULTIPLICITY
  w->owner = aTHX;
 #endif /* VMG_MULTIPLICITY */
-
- w->vtbl = t;
- w->sig  = sig;
-#if VMG_UVAR
- w->uvar = (w->cb_fetch || w->cb_store || w->cb_exists || w->cb_delete);
-#endif /* VMG_UVAR */
+ w->vtbl  = t;
+ w->sig   = sig;
 
  sv = MGWIZ2SV(w);
  mg = sv_magicext(sv, NULL, PERL_MAGIC_ext, &vmg_wizard_vtbl, NULL, 0);