From: Nick Ing-Simmons <nik@tiuk.ti.com>
Date: Mon, 27 May 2002 09:54:46 +0000 (+0000)
Subject: Fix for the IO::Scalar bug (I think).
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=3977871ddaef13bab4556a4c080d3871df7b231f;p=p5sagit%2Fp5-mst-13.2.git

Fix for the IO::Scalar bug (I think).
At tie time break the loop but in a different place:
 A. Increment REFCNT of the RV involved in the self-tie
 B. Decrement REFCNT of the thing RV points to (e.g. the GV)
At mg_free time
 Break the connection between the RV and its referent
 so that we do not try and free it (again).

p4raw-id: //depot/perlio@16808
---

diff --git a/mg.c b/mg.c
index 63de612..299d1bb 100644
--- a/mg.c
+++ b/mg.c
@@ -359,8 +359,17 @@ Perl_mg_free(pTHX_ SV *sv)
 	    else if (mg->mg_len == HEf_SVKEY)
 		SvREFCNT_dec((SV*)mg->mg_ptr);
 	}
-	if (mg->mg_flags & MGf_REFCOUNTED)
-	    SvREFCNT_dec(mg->mg_obj);
+	if (mg->mg_flags & MGf_REFCOUNTED) {
+	    SV *obj = mg->mg_obj;
+	    if (mg->mg_type == PERL_MAGIC_tiedscalar && SvROK(obj) &&
+		(SvRV(obj) == sv || GvIO(SvRV(obj)) == (IO *) sv)) {
+		/* We are already free'ing the self-tied thing
+		   so SvREFCNT_dec must not.
+		 */
+		SvROK_off(obj);
+	    }
+	    SvREFCNT_dec(obj);
+	}
 	Safefree(mg);
     }
     SvMAGIC(sv) = 0;
diff --git a/sv.c b/sv.c
index dd35da7..7d51f32 100644
--- a/sv.c
+++ b/sv.c
@@ -4479,6 +4479,15 @@ Perl_sv_magicext(pTHX_ SV* sv, SV* obj, int how, MGVTBL *vtable,
     else {
 	mg->mg_obj = SvREFCNT_inc(obj);
 	mg->mg_flags |= MGf_REFCOUNTED;
+
+	/* Break self-tie loops */
+	if (how == PERL_MAGIC_tiedscalar && SvROK(obj) &&
+	   (SvRV(obj) == sv || GvIO(SvRV(obj)) == (IO *) sv)) {
+	    /* We have to have a REFCNT to obj, so drop REFCNT
+	       of what if references instead
+	     */
+	    SvREFCNT_dec(SvRV(obj));
+	}
     }
     mg->mg_type = how;
     mg->mg_len = namlen;
@@ -5172,20 +5181,9 @@ Perl_sv_free(pTHX_ SV *sv)
     }
     ATOMIC_DEC_AND_TEST(refcount_is_zero, SvREFCNT(sv));
     if (!refcount_is_zero) {
-	if (SvREFCNT(sv) == 1) {
-	    /* Break self-tie loops */
-	    MAGIC *mg = 0;
-	    SV *obj;
-	    if (SvTYPE(sv) == SVt_PVGV)
-		sv = (SV *)GvIO(sv);
-	    if (!sv || !SvMAGICAL(sv) || SvTYPE(sv) < SVt_PVMG)
-		return;
-            mg = SvTIED_mg(sv, PERL_MAGIC_tiedscalar);
-	    if (mg && (obj = mg->mg_obj) && SvROK(obj) &&
-	        (SvRV(obj) == sv || GvIO(SvRV(obj)) == (IO *) sv)) {
-		sv_unmagic(sv, PERL_MAGIC_tiedscalar);
-	    }
-	}
+	/* Do not be tempted to test SvMAGIC here till scope.c
+	   stops sharing MAGIC * between SVs
+	 */
 	return;
     }
 #ifdef DEBUGGING