Introduce VMG_FORKSAFE

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

diff --git a/Magic.xs b/Magic.xs
index ab8a1c540955ab283216b263df549879b736c688..1dada023c031867f619d812dc50bdc76facc7a78 100644 (file)
--- a/Magic.xs
+++ b/Magic.xs
@@ -36,6 +36,11 @@
 # define dNOOP
 #endif
 
+/* Safe unless stated otherwise in Makefile.PL */
+#ifndef VMG_FORKSAFE
+# define VMG_FORKSAFE 1
+#endif
+
 #ifndef VMG_MULTIPLICITY
 # if defined(MULTIPLICITY) || defined(PERL_IMPLICIT_CONTEXT)
 #  define VMG_MULTIPLICITY 1
@@ -135,8 +140,9 @@ STATIC SV *vmg_clone(pTHX_ SV *sv, tTHX owner) {
 # endif
 #endif
 
-/* uvar magic and Hash::Util::FieldHash were commited with 28419 */
-#if VMG_HAS_PERL_MAINT(5, 9, 4, 28419) || VMG_HAS_PERL(5, 10, 0)
+/* uvar magic and Hash::Util::FieldHash were commited with 28419, but only
+ * enable it on 5.10 */
+#if VMG_HAS_PERL(5, 10, 0)
 # define VMG_UVAR 1
 #else
 # define VMG_UVAR 0
@@ -812,6 +818,10 @@ STATIC int vmg_svt_clear(pTHX_ SV *sv, MAGIC *mg) {
 
 STATIC int vmg_svt_free(pTHX_ SV *sv, MAGIC *mg) {
  const MGWIZ *w;
+#if VMG_HAS_PERL(5, 9, 5)
+ PERL_CONTEXT saved_cx;
+ I32 cxix;
+#endif
  unsigned int had_err, has_err, flags = G_SCALAR | G_EVAL;
  int ret = 0;
 
@@ -849,8 +859,23 @@ STATIC int vmg_svt_free(pTHX_ SV *sv, MAGIC *mg) {
  if (had_err)
   flags |= G_KEEPERR;
 
+#if VMG_HAS_PERL(5, 9, 5)
+ /* This context should not be used anymore, but since we croak in places the
+  * core doesn't even dare to, some pointers to it may remain in the upper call
+  * stack. Make sure call_sv() doesn't clobber it. */
+ if (cxstack_ix < cxstack_max)
+  cxix = cxstack_ix + 1;
+ else
+  cxix = Perl_cxinc(aTHX);
+ saved_cx = cxstack[cxix];
+#endif
+
  call_sv(w->cb_free, flags);
 
+#if VMG_HAS_PERL(5, 9, 5)
+ cxstack[cxix] = saved_cx;
+#endif
+
  has_err = SvTRUE(ERRSV);
  if (IN_PERL_COMPILETIME && !had_err && has_err)
   ++PL_error_count;
@@ -860,15 +885,6 @@ STATIC int vmg_svt_free(pTHX_ SV *sv, MAGIC *mg) {
  FREETMPS;
  LEAVE;
 
- if (has_err) {
-  /* Get the eval context that was pushed by call_sv, and fake an entry for the
-   * namesv, as die_where will need it to be non NULL later */
-  PERL_CONTEXT *cx = cxstack + cxstack_ix + 1;
-  if (!cx->blk_eval.old_namesv)
-   cx->blk_eval.old_namesv
-                 = sv_2mortal(newSVpvn_share("Variable/Magic/DUMMY.pm", 23, 0));
- }
-
  /* 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);
@@ -1028,8 +1044,16 @@ STATIC int vmg_wizard_free(pTHX_ SV *wiz, MAGIC *mg) {
   if (hv_delete(MY_CXT.wizards, buf, sprintf(buf, "%u", w->sig), 0) != wiz)
    return 0;
  }
- SvFLAGS(wiz) |= SVf_BREAK;
- FREETMPS;
+
+ /* Unmortalize the wizard to avoid it being freed in weird places. */
+ if (SvTEMP(wiz) && !SvREFCNT(wiz)) {
+  const I32 myfloor = PL_tmps_floor;
+  I32 i;
+  for (i = PL_tmps_ix; i > myfloor; --i) {
+   if (PL_tmps_stack[i] == wiz)
+    PL_tmps_stack[i] = NULL;
+  }
+ }
 
  if (w->cb_data)   SvREFCNT_dec(SvRV(w->cb_data));
  if (w->cb_get)    SvREFCNT_dec(SvRV(w->cb_get));
@@ -1244,6 +1268,7 @@ BOOT:
                     newSVuv(VMG_COMPAT_SCALAR_LENGTH_NOLEN));
  newCONSTSUB(stash, "VMG_PERL_PATCHLEVEL", newSVuv(VMG_PERL_PATCHLEVEL));
  newCONSTSUB(stash, "VMG_THREADSAFE",      newSVuv(VMG_THREADSAFE));
+ newCONSTSUB(stash, "VMG_FORKSAFE",        newSVuv(VMG_FORKSAFE));
  newCONSTSUB(stash, "VMG_OP_INFO_NAME",    newSVuv(VMG_OP_INFO_NAME));
  newCONSTSUB(stash, "VMG_OP_INFO_OBJECT",  newSVuv(VMG_OP_INFO_OBJECT));
 }
@@ -1408,10 +1433,11 @@ OUTPUT:
 
 SV *getsig(SV *wiz)
 PROTOTYPE: $
+PREINIT:
+ U16 sig;
 CODE:
- if (!SvROK(wiz))
-  croak(vmg_invalid_wiz);
- RETVAL = newSVuv(SV2MGWIZ(SvRV(wiz))->sig);
+ sig = vmg_wizard_sig(wiz);
+ RETVAL = newSVuv(sig);
 OUTPUT:
  RETVAL
 
@@ -1448,7 +1474,7 @@ PPCODE:
  sig  = vmg_wizard_sig(wiz);
  data = vmg_data_get(SvRV(sv), sig);
  if (!data)
-  XSRETURN_UNDEF;
+  XSRETURN_EMPTY;
  ST(0) = data;
  XSRETURN(1);