Fix bug #40407: after a seek on a PerlIO::scalar filehandle,

ensure there's a string buffer in the scalar

p4raw-id: //depot/perl@29751

1 files changed, 4 insertions, 0 deletions

diff --git a/ext/PerlIO/scalar/scalar.xs b/ext/PerlIO/scalar/scalar.xs
index 319c85137d..b31e681c21 100644
--- a/ext/PerlIO/scalar/scalar.xs
+++ b/ext/PerlIO/scalar/scalar.xs
@@ -108,6 +108,10 @@ PerlIOScalar_seek(pTHX_ PerlIO * f, Off_t offset, int whence)
 	Zero(SvPVX(s->var) + oldcur, newlen - oldcur, char);
 	/* No SvCUR_set(), though.  This is just a seek, not a write. */
     }
+    else if (!SvPVX(s->var)) {
+	/* ensure there's always a character buffer */
+	(void)SvGROW(s->var,1);
+    }
     SvPOK_on(s->var);
     return 0;
 }