handle magic in local correctly

the local SV now gets a copy of any container magic, and no value
magic; in the past the whole magic chain was either shared or
moved

p4raw-id: //depot/perl@24942

1 files changed, 62 insertions, 0 deletions

diff --git a/mg.c b/mg.c
index bd5acdfe57..366961984f 100644
--- a/mg.c
+++ b/mg.c
@@ -381,6 +381,68 @@ Perl_mg_copy(pTHX_ SV *sv, SV *nsv, const char *key, I32 klen)
 }
 
 /*
+=for apidoc mg_localize
+
+Copy some of the magic from an existing SV to new localized version of
+that SV. Container magic (eg %ENV, $1, tie) gets copied, value magic
+doesn't (eg taint, pos).
+
+=cut
+*/
+
+void
+Perl_mg_localize(pTHX_ SV *sv, SV *nsv)
+{
+    MAGIC *mg;
+    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
+	const MGVTBL* const vtbl = mg->mg_virtual;
+	switch (mg->mg_type) {
+	/* value magic types: don't copy */
+	case PERL_MAGIC_bm:
+	case PERL_MAGIC_fm:
+	case PERL_MAGIC_regex_global:
+	case PERL_MAGIC_nkeys:
+#ifdef USE_LOCALE_COLLATE
+	case PERL_MAGIC_collxfrm:
+#endif
+	case PERL_MAGIC_qr:
+	case PERL_MAGIC_taint:
+	case PERL_MAGIC_vec:
+	case PERL_MAGIC_vstring:
+	case PERL_MAGIC_utf8:
+	case PERL_MAGIC_substr:
+	case PERL_MAGIC_defelem:
+	case PERL_MAGIC_arylen:
+	case PERL_MAGIC_pos:
+	case PERL_MAGIC_backref:
+	case PERL_MAGIC_arylen_p:
+	case PERL_MAGIC_rhash:
+	case PERL_MAGIC_symtab:
+	    continue;
+	}
+		
+	if ((mg->mg_flags & MGf_COPY) && vtbl->svt_copy) {
+	    /* XXX calling the copy method is probably not correct. DAPM */
+	    (void)CALL_FPTR(vtbl->svt_copy)(aTHX_ sv, mg, nsv,
+				    mg->mg_ptr, mg->mg_len);
+	}
+	else {
+	    sv_magicext(nsv, mg->mg_obj, mg->mg_type, vtbl,
+			    mg->mg_ptr, mg->mg_len);
+	}
+	/* container types should remain read-only across localization */
+	SvFLAGS(nsv) |= SvREADONLY(sv);
+    }
+
+    if (SvTYPE(nsv) >= SVt_PVMG && SvMAGIC(nsv)) {
+	SvFLAGS(nsv) |= SvMAGICAL(sv);
+	PL_localizing = 1;
+	SvSETMAGIC(nsv);
+	PL_localizing = 0;
+    }	    
+}
+
+/*
 =for apidoc mg_free
 
 Free any magic storage used by the SV.  See C<sv_magic>.