Better fix for #119529

<$fh> used to loop if $fh was opened to an in-memory handle containing
a reference.

Commit 552908b174 fixed the loop by forcing a reference to a string
when the handle was created.  It did not take into account that the
reference might be read-only.  It was also insufficient, in that
the target scalar could be set to a reference after the handle
was created.

The real reason it was looping was that the code for returning and
setting the size of the buffer was not handling non-PVs properly
(unless they were globs, which were special-cased).  It might return
0, and it might not, depending on what the internal SV field hap-
pened to hold.

This caused looping under 5.12 and onwards, but even in 5.10 <$fh>
returned nothing.

In this case, deleting code makes things just work.

Reverting the hunk from 552908b174 stops appending to refs from work-
ing, so I tweaked PerlIOScalar_pushed to fix that (which also reduced
the amount of code).

2 files changed, 17 insertions, 18 deletions

diff --git a/ext/PerlIO-scalar/scalar.xs b/ext/PerlIO-scalar/scalar.xs
index 95668e7a2c..fd8ac67d4b 100644
--- a/ext/PerlIO-scalar/scalar.xs
+++ b/ext/PerlIO-scalar/scalar.xs
@@ -48,11 +48,7 @@ PerlIOScalar_pushed(pTHX_ PerlIO * f, const char *mode, SV * arg,
     else {
 	s->var = newSVpvn("", 0);
     }
-    if (SvROK(s->var))
-        /* force refs, overload etc to be plain strings */
-        (void)SvPV_force_nomg_nolen(s->var);
-    else
-        SvUPGRADE(s->var, SVt_PV);
+    SvUPGRADE(s->var, SVt_PV);
 
     code = PerlIOBase_pushed(aTHX_ f, mode, Nullsv, tab);
     if (!SvOK(s->var) || (PerlIOBase(f)->flags) & PERLIO_F_TRUNCATE)
@@ -69,10 +65,7 @@ PerlIOScalar_pushed(pTHX_ PerlIO * f, const char *mode, SV * arg,
 	return -1;
     }
     if ((PerlIOBase(f)->flags) & PERLIO_F_APPEND)
-    {
-	sv_force_normal(s->var);
-	s->posn = SvCUR(s->var);
-    }
+	s->posn = sv_len(s->var);
     else
 	s->posn = 0;
     SvSETMAGIC(s->var);
@@ -270,10 +263,7 @@ PerlIOScalar_get_cnt(pTHX_ PerlIO * f)
     if (PerlIOBase(f)->flags & PERLIO_F_CANREAD) {
 	PerlIOScalar *s = PerlIOSelf(f, PerlIOScalar);
 	STRLEN len;
-	SvGETMAGIC(s->var);
-	if (isGV_with_GP(s->var))
-	    (void)SvPV(s->var,len);
-	else len = SvCUR(s->var);
+	(void)SvPV(s->var,len);
 	if (len > (STRLEN) s->posn)
 	    return len - (STRLEN)s->posn;
 	else
@@ -299,9 +289,7 @@ PerlIOScalar_set_ptrcnt(pTHX_ PerlIO * f, STDCHAR * ptr, SSize_t cnt)
     PerlIOScalar *s = PerlIOSelf(f, PerlIOScalar);
     STRLEN len;
     PERL_UNUSED_ARG(ptr);
-    SvGETMAGIC(s->var);
-    if (isGV_with_GP(s->var)) (void)SvPV(s->var,len);
-    else len = SvCUR(s->var);
+    (void)SvPV(s->var,len);
     s->posn = len - cnt;
 }
 
diff --git a/ext/PerlIO-scalar/t/scalar.t b/ext/PerlIO-scalar/t/scalar.t
index f5ee47e471..4de54f7ed0 100644
--- a/ext/PerlIO-scalar/t/scalar.t
+++ b/ext/PerlIO-scalar/t/scalar.t
@@ -16,7 +16,7 @@ use Fcntl qw(SEEK_SET SEEK_CUR SEEK_END); # Not 0, 1, 2 everywhere.
 
 $| = 1;
 
-use Test::More tests => 109;
+use Test::More tests => 112;
 
 my $fh;
 my $var = "aaa\n";
@@ -463,11 +463,22 @@ my $byte_warning = "Strings with code points over 0xFF may not be mapped into in
     is_deeply(\@warnings, [ $byte_warning ], "check warning");
 }
 
-#  RT #119529: non-string should be forced into a string
+#  RT #119529: Reading refs should not loop
 
 {
     my $x = \42;
     open my $fh, "<", \$x;
     my $got = <$fh>; # this used to loop
     like($got, qr/^SCALAR\(0x[0-9a-f]+\)$/, "ref to a ref");
+    is ref $x, "SCALAR", "target scalar is still a reference";
+}
+
+# Appending to refs
+{
+    my $x = \42;
+    my $as_string = "$x";
+    open my $refh, ">>", \$x;
+    is ref $x, "SCALAR", 'still a ref after opening for appending';
+    print $refh "boo\n";
+    is $x, $as_string."boo\n", 'string gets appended to ref';
 }